Add proto v2 archive command with HTTP support

Add proto v2 archive command with HTTP support

[Josh Steadmon]

This series adds a new protocol v2 command for archiving, and allows
this command to work over HTTP(S). This was previously discussed in [1].
I've CCed everyone who participated in that discussion.

[1]: https://public-inbox.org/git/CANq=j3tK7QeBJOC7VNWkh4+WBNibMJJp5YUkd9te5NaYwukAow@mail.gmail.com/

[PATCH 1/3] archive: use packet_reader for communications

[Josh Steadmon]

Using packet_reader will simplify version detection and capability
handling, which will make implementation of protocol v2 support in
git-archive easier.

Signed-off-by: Josh Steadmon <steadmon@google.com>
---
 builtin/archive.c | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/builtin/archive.c b/builtin/archive.c
index e74f67539..e54fc39ad 100644
--- a/builtin/archive.c
+++ b/builtin/archive.c
@@ -27,10 +27,11 @@ static int run_remote_archiver(int argc, const char **argv,
 			       const char *remote, const char *exec,
 			       const char *name_hint)
 {
-	char *buf;
 	int fd[2], i, rv;
 	struct transport *transport;
 	struct remote *_remote;
+	struct packet_reader reader;
+	enum packet_read_status status;
 
 	_remote = remote_get(remote);
 	if (!_remote->url[0])
@@ -38,6 +39,8 @@ static int run_remote_archiver(int argc, const char **argv,
 	transport = transport_get(_remote, _remote->url[0]);
 	transport_connect(transport, "git-upload-archive", exec, fd);
 
+	packet_reader_init(&reader, fd[0], NULL, 0, PACKET_READ_CHOMP_NEWLINE);
+
 	/*
 	 * Inject a fake --format field at the beginning of the
 	 * arguments, with the format inferred from our output
@@ -53,18 +56,20 @@ static int run_remote_archiver(int argc, const char **argv,
 		packet_write_fmt(fd[1], "argument %s\n", argv[i]);
 	packet_flush(fd[1]);
 
-	buf = packet_read_line(fd[0], NULL);
-	if (!buf)
+	status = packet_reader_read(&reader);
+
+	if (status == PACKET_READ_FLUSH)
 		die(_("git archive: expected ACK/NAK, got a flush packet"));
-	if (strcmp(buf, "ACK")) {
-		if (starts_with(buf, "NACK "))
-			die(_("git archive: NACK %s"), buf + 5);
-		if (starts_with(buf, "ERR "))
-			die(_("remote error: %s"), buf + 4);
+	if (strcmp(reader.buffer, "ACK")) {
+		if (starts_with(reader.buffer, "NACK "))
+			die(_("git archive: NACK %s"), reader.buffer + 5);
+		if (starts_with(reader.buffer, "ERR "))
+			die(_("remote error: %s"), reader.buffer + 4);
 		die(_("git archive: protocol error"));
 	}
 
-	if (packet_read_line(fd[0], NULL))
+	status = packet_reader_read(&reader);
+	if (status != PACKET_READ_FLUSH)
 		die(_("git archive: expected a flush"));
 
 	/* Now, start reading from fd[0] and spit it out to stdout */
-- 
2.19.0.397.gdd90340f6a-goog

Re: [PATCH 1/3] archive: use packet_reader for communications

[Stefan Beller]

On Tue, Sep 11, 2018 at 10:35 PM Josh Steadmon <steadmon@google.com> wrote:
>
> Using packet_reader will simplify version detection and capability
> handling, which will make implementation of protocol v2 support in
> git-archive easier.
>
> Signed-off-by: Josh Steadmon <steadmon@google.com>

Reviewed-by: Stefan Beller <sbeller@google.com>

Re: [PATCH 1/3] archive: use packet_reader for communications

[Junio C Hamano]

Josh Steadmon <steadmon@google.com> writes:

> Using packet_reader will simplify version detection and capability
> handling, which will make implementation of protocol v2 support in
> git-archive easier.

Is this meant as a change in implementation without any change in
behaviour?

> Signed-off-by: Josh Steadmon <steadmon@google.com>
> ---
>  builtin/archive.c | 23 ++++++++++++++---------
>  1 file changed, 14 insertions(+), 9 deletions(-)
>
> diff --git a/builtin/archive.c b/builtin/archive.c
> index e74f67539..e54fc39ad 100644
> --- a/builtin/archive.c
> +++ b/builtin/archive.c
> @@ -27,10 +27,11 @@ static int run_remote_archiver(int argc, const char **argv,
>  			       const char *remote, const char *exec,
>  			       const char *name_hint)
>  {
> -	char *buf;
>  	int fd[2], i, rv;
>  	struct transport *transport;
>  	struct remote *_remote;
> +	struct packet_reader reader;
> +	enum packet_read_status status;
>  
>  	_remote = remote_get(remote);
>  	if (!_remote->url[0])
> @@ -38,6 +39,8 @@ static int run_remote_archiver(int argc, const char **argv,
>  	transport = transport_get(_remote, _remote->url[0]);
>  	transport_connect(transport, "git-upload-archive", exec, fd);
>  
> +	packet_reader_init(&reader, fd[0], NULL, 0, PACKET_READ_CHOMP_NEWLINE);
> +
>  	/*
>  	 * Inject a fake --format field at the beginning of the
>  	 * arguments, with the format inferred from our output
> @@ -53,18 +56,20 @@ static int run_remote_archiver(int argc, const char **argv,
>  		packet_write_fmt(fd[1], "argument %s\n", argv[i]);
>  	packet_flush(fd[1]);
>  
> -	buf = packet_read_line(fd[0], NULL);
> -	if (!buf)
> +	status = packet_reader_read(&reader);
> +
> +	if (status == PACKET_READ_FLUSH)
>  		die(_("git archive: expected ACK/NAK, got a flush packet"));

It is true that packet_read_line() returns a NULL on flush, but the
function also returns NULL on other conditions for which underlying
packet_read() returns 0 (or negative) length.  EOF, normal data with
zero length (i.e. packet length itself is 4), and DELIM packets
would all have led to this die() in the original code.  We fail to
notice that we got something unexpected when we were expecting to
get a normal packet with ACK or NACK on it.

> -	if (strcmp(buf, "ACK")) {
> -		if (starts_with(buf, "NACK "))
> -			die(_("git archive: NACK %s"), buf + 5);
> -		if (starts_with(buf, "ERR "))
> -			die(_("remote error: %s"), buf + 4);
> +	if (strcmp(reader.buffer, "ACK")) {

The way I read packet_reader_read()'s implementation and existing
callers (like the ones in fetch-pack.c) tells me that consumers
should not be looking at "reader.buffer"; they should instead be
reading from "reader.line".

> +		if (starts_with(reader.buffer, "NACK "))
> +			die(_("git archive: NACK %s"), reader.buffer + 5);
> +		if (starts_with(reader.buffer, "ERR "))
> +			die(_("remote error: %s"), reader.buffer + 4);
>  		die(_("git archive: protocol error"));
>  	}
>  
> -	if (packet_read_line(fd[0], NULL))
> +	status = packet_reader_read(&reader);
> +	if (status != PACKET_READ_FLUSH)
>  		die(_("git archive: expected a flush"));

This makes me wonder what happens if we got an EOF instead.  We fail
to notice protocol error here, but do the code after this part
correctly handle the situation?

>  	/* Now, start reading from fd[0] and spit it out to stdout */

Re: [PATCH 1/3] archive: use packet_reader for communications

[Junio C Hamano]

Junio C Hamano <gitster@pobox.com> writes:

>> -	if (packet_read_line(fd[0], NULL))
>> +	status = packet_reader_read(&reader);
>> +	if (status != PACKET_READ_FLUSH)
>>  		die(_("git archive: expected a flush"));
>
> This makes me wonder what happens if we got an EOF instead.  We fail
> to notice protocol error here, but do the code after this part
> correctly handle the situation?

Sorry, this part of my comment is completely backwards.

We require they send a flush, not a 0-length data packet of length
4, and otherwise we die, even though we used to treate 0-length data
packet of length 4 just like a flush.

So this is making the code more strict than the original.  As long
as all the existing implementations correctly use flush here, there
would be no unintended regression, but it bothers me that we have to
even worry if these behaviour changes affect the already deployed
software negatively.

>
>>  	/* Now, start reading from fd[0] and spit it out to stdout */

[PATCH 2/3] archive: implement protocol v2 archive command

[Josh Steadmon]

This adds a new archive command for protocol v2. The command expects
arguments in the form "argument X" which are passed unmodified to
git-upload-archive--writer.

This command works over the file://, Git, and SSH transports. HTTP
support will be added in a separate patch.

Signed-off-by: Josh Steadmon <steadmon@google.com>
---
 builtin/archive.c        | 45 +++++++++++++++++++++++++++-------------
 builtin/upload-archive.c | 44 ++++++++++++++++++++++++++++++++++++---
 t/t5000-tar-tree.sh      |  5 +++++
 3 files changed, 77 insertions(+), 17 deletions(-)

diff --git a/builtin/archive.c b/builtin/archive.c
index e54fc39ad..73831887d 100644
--- a/builtin/archive.c
+++ b/builtin/archive.c
@@ -5,9 +5,11 @@
 #include "cache.h"
 #include "builtin.h"
 #include "archive.h"
+#include "connect.h"
 #include "transport.h"
 #include "parse-options.h"
 #include "pkt-line.h"
+#include "protocol.h"
 #include "sideband.h"
 
 static void create_output_file(const char *output_file)
@@ -23,6 +25,13 @@ static void create_output_file(const char *output_file)
 	}
 }
 
+static int do_v2_command_and_cap(int out)
+{
+	packet_write_fmt(out, "command=archive\n");
+	/* Capability list would go here, if we had any. */
+	packet_delim(out);
+}
+
 static int run_remote_archiver(int argc, const char **argv,
 			       const char *remote, const char *exec,
 			       const char *name_hint)
@@ -32,6 +41,7 @@ static int run_remote_archiver(int argc, const char **argv,
 	struct remote *_remote;
 	struct packet_reader reader;
 	enum packet_read_status status;
+	enum protocol_version version;
 
 	_remote = remote_get(remote);
 	if (!_remote->url[0])
@@ -41,6 +51,11 @@ static int run_remote_archiver(int argc, const char **argv,
 
 	packet_reader_init(&reader, fd[0], NULL, 0, PACKET_READ_CHOMP_NEWLINE);
 
+	version = discover_version(&reader);
+
+	if (version == protocol_v2)
+		do_v2_command_and_cap(fd[1]);
+
 	/*
 	 * Inject a fake --format field at the beginning of the
 	 * arguments, with the format inferred from our output
@@ -56,22 +71,24 @@ static int run_remote_archiver(int argc, const char **argv,
 		packet_write_fmt(fd[1], "argument %s\n", argv[i]);
 	packet_flush(fd[1]);
 
-	status = packet_reader_read(&reader);
-
-	if (status == PACKET_READ_FLUSH)
-		die(_("git archive: expected ACK/NAK, got a flush packet"));
-	if (strcmp(reader.buffer, "ACK")) {
-		if (starts_with(reader.buffer, "NACK "))
-			die(_("git archive: NACK %s"), reader.buffer + 5);
-		if (starts_with(reader.buffer, "ERR "))
-			die(_("remote error: %s"), reader.buffer + 4);
-		die(_("git archive: protocol error"));
+	if (version == protocol_v0) {
+		status = packet_reader_read(&reader);
+
+		if (status == PACKET_READ_FLUSH)
+			die(_("git archive: expected ACK/NAK, got a flush packet"));
+		if (strcmp(reader.buffer, "ACK")) {
+			if (starts_with(reader.buffer, "NACK "))
+				die(_("git archive: NACK %s"), reader.buffer + 5);
+			if (starts_with(reader.buffer, "ERR "))
+				die(_("remote error: %s"), reader.buffer + 4);
+			die(_("git archive: protocol error"));
+		}
+
+		status = packet_reader_read(&reader);
+		if (status != PACKET_READ_FLUSH)
+			die(_("git archive: expected a flush"));
 	}
 
-	status = packet_reader_read(&reader);
-	if (status != PACKET_READ_FLUSH)
-		die(_("git archive: expected a flush"));
-
 	/* Now, start reading from fd[0] and spit it out to stdout */
 	rv = recv_sideband("archive", fd[0], 1);
 	rv |= transport_disconnect(transport);
diff --git a/builtin/upload-archive.c b/builtin/upload-archive.c
index 25d911635..534e8fd56 100644
--- a/builtin/upload-archive.c
+++ b/builtin/upload-archive.c
@@ -5,6 +5,7 @@
 #include "builtin.h"
 #include "archive.h"
 #include "pkt-line.h"
+#include "protocol.h"
 #include "sideband.h"
 #include "run-command.h"
 #include "argv-array.h"
@@ -73,13 +74,53 @@ static ssize_t process_input(int child_fd, int band)
 	return sz;
 }
 
+static int handle_v2_command_and_cap(void)
+{
+	struct packet_reader reader;
+	enum packet_read_status status;
+
+	packet_reader_init(&reader, 0, NULL, 0, PACKET_READ_CHOMP_NEWLINE);
+
+	packet_write_fmt(1, "version 2\n");
+	/*
+	 * We don't currently send any capabilities, but maybe we could list
+	 * supported archival formats?
+	 */
+	packet_flush(1);
+
+	status = packet_reader_read(&reader);
+	if (status != PACKET_READ_NORMAL ||
+	    strcmp(reader.buffer, "command=archive"))
+		die(_("upload-archive: expected command=archive"));
+	while (status == PACKET_READ_NORMAL) {
+		/* We don't currently expect any client capabilities, but we
+		 * should still read (and ignore) any that happen to get sent.
+		 */
+		status = packet_reader_read(&reader);
+	}
+	if (status != PACKET_READ_DELIM)
+		die(_("upload-archive: expected delim packet"));
+
+	/* Let git-upload-archive--writer handle the arguments. */
+
+	return 0;
+}
+
 int cmd_upload_archive(int argc, const char **argv, const char *prefix)
 {
 	struct child_process writer = { argv };
+	enum protocol_version version = determine_protocol_version_server();
 
 	if (argc == 2 && !strcmp(argv[1], "-h"))
 		usage(upload_archive_usage);
 
+	if (version == protocol_v2)
+		handle_v2_command_and_cap();
+	else {
+		packet_write_fmt(1, "ACK\n");
+		packet_flush(1);
+	}
+
 	/*
 	 * Set up sideband subprocess.
 	 *
@@ -96,9 +137,6 @@ int cmd_upload_archive(int argc, const char **argv, const char *prefix)
 		die("upload-archive: %s", strerror(err));
 	}
 
-	packet_write_fmt(1, "ACK\n");
-	packet_flush(1);
-
 	while (1) {
 		struct pollfd pfd[2];
 
diff --git a/t/t5000-tar-tree.sh b/t/t5000-tar-tree.sh
index 2a97b27b0..4be74d6e9 100755
--- a/t/t5000-tar-tree.sh
+++ b/t/t5000-tar-tree.sh
@@ -145,6 +145,11 @@ test_expect_success \
 
 check_tar b
 
+test_expect_success 'protocol v2 for remote' '
+	GIT_PROTOCOL="version=2" git archive --remote=. HEAD >v2_remote.tar
+'
+check_tar v2_remote
+
 test_expect_success 'git archive --prefix=prefix/' '
 	git archive --prefix=prefix/ HEAD >with_prefix.tar
 '
-- 
2.19.0.397.gdd90340f6a-goog

Re: [PATCH 2/3] archive: implement protocol v2 archive command

[Stefan Beller]

On Tue, Sep 11, 2018 at 10:36 PM Josh Steadmon <steadmon@google.com> wrote:
>
> This adds a new archive command for protocol v2. The command expects
> arguments in the form "argument X" which are passed unmodified to
> git-upload-archive--writer.
>
> This command works over the file://, Git, and SSH transports. HTTP
> support will be added in a separate patch.
>
> Signed-off-by: Josh Steadmon <steadmon@google.com>
> ---
>  builtin/archive.c        | 45 +++++++++++++++++++++++++++-------------
>  builtin/upload-archive.c | 44 ++++++++++++++++++++++++++++++++++++---
>  t/t5000-tar-tree.sh      |  5 +++++
>  3 files changed, 77 insertions(+), 17 deletions(-)
>
> diff --git a/builtin/archive.c b/builtin/archive.c
> index e54fc39ad..73831887d 100644
> --- a/builtin/archive.c
> +++ b/builtin/archive.c
> @@ -5,9 +5,11 @@
>  #include "cache.h"
>  #include "builtin.h"
>  #include "archive.h"
> +#include "connect.h"
>  #include "transport.h"
>  #include "parse-options.h"
>  #include "pkt-line.h"
> +#include "protocol.h"
>  #include "sideband.h"
>
>  static void create_output_file(const char *output_file)
> @@ -23,6 +25,13 @@ static void create_output_file(const char *output_file)
>         }
>  }
>
> +static int do_v2_command_and_cap(int out)
> +{
> +       packet_write_fmt(out, "command=archive\n");
> +       /* Capability list would go here, if we had any. */
> +       packet_delim(out);
> +}
> +
>  static int run_remote_archiver(int argc, const char **argv,
>                                const char *remote, const char *exec,
>                                const char *name_hint)
> @@ -32,6 +41,7 @@ static int run_remote_archiver(int argc, const char **argv,
>         struct remote *_remote;
>         struct packet_reader reader;
>         enum packet_read_status status;
> +       enum protocol_version version;
>
>         _remote = remote_get(remote);
>         if (!_remote->url[0])
> @@ -41,6 +51,11 @@ static int run_remote_archiver(int argc, const char **argv,
>
>         packet_reader_init(&reader, fd[0], NULL, 0, PACKET_READ_CHOMP_NEWLINE);
>
> +       version = discover_version(&reader);
> +
> +       if (version == protocol_v2)
> +               do_v2_command_and_cap(fd[1]);
> +
>         /*
>          * Inject a fake --format field at the beginning of the
>          * arguments, with the format inferred from our output
> @@ -56,22 +71,24 @@ static int run_remote_archiver(int argc, const char **argv,
>                 packet_write_fmt(fd[1], "argument %s\n", argv[i]);
>         packet_flush(fd[1]);
>
> -       status = packet_reader_read(&reader);
> -
> -       if (status == PACKET_READ_FLUSH)
> -               die(_("git archive: expected ACK/NAK, got a flush packet"));
> -       if (strcmp(reader.buffer, "ACK")) {
> -               if (starts_with(reader.buffer, "NACK "))
> -                       die(_("git archive: NACK %s"), reader.buffer + 5);
> -               if (starts_with(reader.buffer, "ERR "))
> -                       die(_("remote error: %s"), reader.buffer + 4);
> -               die(_("git archive: protocol error"));

Maybe we also want to support v1
(which is v0 prefixed with one pkt_line saying it is v1).

    If (version == protocol_v1)
        /* drop version v1 line, and then follow v0 logic. */
        packet_reader_read(&reader);

Do we care about v1, or do we just ignore it here? why?
(Don't answer me here, but rather put it in the commit message)

> +       if (version == protocol_v0) {
> +               status = packet_reader_read(&reader);
> +
> +               if (status == PACKET_READ_FLUSH)
> +                       die(_("git archive: expected ACK/NAK, got a flush packet"));
> +               if (strcmp(reader.buffer, "ACK")) {
> +                       if (starts_with(reader.buffer, "NACK "))
> +                               die(_("git archive: NACK %s"), reader.buffer + 5);
> +                       if (starts_with(reader.buffer, "ERR "))
> +                               die(_("remote error: %s"), reader.buffer + 4);
> +                       die(_("git archive: protocol error"));
> +               }
> +
> +               status = packet_reader_read(&reader);
> +               if (status != PACKET_READ_FLUSH)
> +                       die(_("git archive: expected a flush"));
>         }
>
> -       status = packet_reader_read(&reader);
> -       if (status != PACKET_READ_FLUSH)
> -               die(_("git archive: expected a flush"));
> -
>         /* Now, start reading from fd[0] and spit it out to stdout */
>         rv = recv_sideband("archive", fd[0], 1);
>         rv |= transport_disconnect(transport);
> diff --git a/builtin/upload-archive.c b/builtin/upload-archive.c
> index 25d911635..534e8fd56 100644
> --- a/builtin/upload-archive.c
> +++ b/builtin/upload-archive.c
> @@ -5,6 +5,7 @@
>  #include "builtin.h"
>  #include "archive.h"
>  #include "pkt-line.h"
> +#include "protocol.h"
>  #include "sideband.h"
>  #include "run-command.h"
>  #include "argv-array.h"
> @@ -73,13 +74,53 @@ static ssize_t process_input(int child_fd, int band)
>         return sz;
>  }
>
> +static int handle_v2_command_and_cap(void)
> +{
> +       struct packet_reader reader;
> +       enum packet_read_status status;
> +
> +       packet_reader_init(&reader, 0, NULL, 0, PACKET_READ_CHOMP_NEWLINE);
> +
> +       packet_write_fmt(1, "version 2\n");
> +       /*
> +        * We don't currently send any capabilities, but maybe we could list
> +        * supported archival formats?
> +        */
> +       packet_flush(1);
> +
> +       status = packet_reader_read(&reader);
> +       if (status != PACKET_READ_NORMAL ||
> +           strcmp(reader.buffer, "command=archive"))
> +               die(_("upload-archive: expected command=archive"));
> +       while (status == PACKET_READ_NORMAL) {
> +               /* We don't currently expect any client capabilities, but we
> +                * should still read (and ignore) any that happen to get sent.

/*
 * Makes sense to ignore the client capabilities here,
 * but the multi line comments take their opening
 * and closing line on a separate line. just like above.
 */

> +                */
> +               status = packet_reader_read(&reader);
> +       }
> +       if (status != PACKET_READ_DELIM)
> +               die(_("upload-archive: expected delim packet"));

This is upload-archive, which is a low level plumbing command
(see the main man page of git for an explanation of that category),
so we do not translate the error/die() calls. Besides, this is executed
on the server, which might have a different locale than the requesting
client?

Would asking for a setlocale() on the server side be an unreasonable
feature request for the capabilities (in a follow up patch, and then not
just for archive but also fetch/push, etc.)?

>  int cmd_upload_archive(int argc, const char **argv, const char *prefix)
>  {
>         struct child_process writer = { argv };
> +       enum protocol_version version = determine_protocol_version_server();
>
>         if (argc == 2 && !strcmp(argv[1], "-h"))
>                 usage(upload_archive_usage);
>
> +       if (version == protocol_v2)
> +               handle_v2_command_and_cap();
> +       else {

So if the client asked for v1, we still fall back to v0 here,
which answers my question above.

> +               packet_write_fmt(1, "ACK\n");
> +               packet_flush(1);
> +       }
> +
>         /*
>          * Set up sideband subprocess.
>          *
> @@ -96,9 +137,6 @@ int cmd_upload_archive(int argc, const char **argv, const char *prefix)
>                 die("upload-archive: %s", strerror(err));
>         }
>
> -       packet_write_fmt(1, "ACK\n");
> -       packet_flush(1);
> -
>         while (1) {
>                 struct pollfd pfd[2];
>
> diff --git a/t/t5000-tar-tree.sh b/t/t5000-tar-tree.sh
> index 2a97b27b0..4be74d6e9 100755
> --- a/t/t5000-tar-tree.sh
> +++ b/t/t5000-tar-tree.sh
> @@ -145,6 +145,11 @@ test_expect_success \
>
>  check_tar b
>
> +test_expect_success 'protocol v2 for remote' '
> +       GIT_PROTOCOL="version=2" git archive --remote=. HEAD >v2_remote.tar
> +'
> +check_tar v2_remote

Our current standard is to keep all executions inside
a test_expect_* block, but here it is hard to comply with
that as the check_tar function contains test_expect_*
and calling test_expect_* from within itself doesn't work
with our test suite.

So bonus points for a refactoring to bring t5000 up to
our current standard (c.f. t0020 for a reasonable new
code, and t2002 for older code, though that only covers
syntax, not functions)

The check itself is just testing that giving GIT_PROTOCOL=2
in the environment also let's you obtain an archive. It doesn't
test if the actual communication *is* v2.
See 5e3548ef161 (fetch: send server options when using
protocol v2, 2018-04-23) for an example how to sniff on the
network traffic in tests, i.e. use GIT_TRACE_PACKET=...
and grep on that?

Thanks,
Stefan

Re: [PATCH 2/3] archive: implement protocol v2 archive command

[Ævar Arnfjörð Bjarmason]

On Wed, Sep 12 2018, Stefan Beller wrote:

> On Tue, Sep 11, 2018 at 10:36 PM Josh Steadmon <steadmon@google.com> wrote:
>> +                */
>> +               status = packet_reader_read(&reader);
>> +       }
>> +       if (status != PACKET_READ_DELIM)
>> +               die(_("upload-archive: expected delim packet"));
>
> This is upload-archive, which is a low level plumbing command
> (see the main man page of git for an explanation of that category),
> so we do not translate the error/die() calls. Besides, this is executed
> on the server, which might have a different locale than the requesting
> client?
>
> Would asking for a setlocale() on the server side be an unreasonable
> feature request for the capabilities (in a follow up patch, and then not
> just for archive but also fetch/push, etc.)?

This would be very nice to have, but as you suggest in some follow-up
change.

I think though that instead of doing setlocale() it would be better to
pass some flag saying we're operating in a machine-readable mode, and
then we'd (as part of the protocol defintion) say we're going to emit
GIT_ERR_UPLOAD_ARCHIVE_EXPECTED_DELIM_PACKET or whatever.

Advantages of doing that over a server-side setlocale():

 1) Purely for translation purposes, users can update to a newer client
    to get new translations, even though they're talking to an old
    server.

 2) Again, only for translation purposes, servers may not have the
    appropriate locales generated and/or linked to libgettext.

 3) Ditto, some clients that aren't git.git may want/need to emit
    different translation messages to their consumers than what we have,
    think some GUI client / Emacs magit etc. whose UI is different from
    ours.

 4) Aside from translation purposes, getting a machine-readable
    "push/pull" etc. mode would be very handy. E.g. now you need to
    parse stderr to see why exactly your push failed (hook denied, or
    non-fast-forward, or non-fast-forward where there was a lock race
    condition? ...).

I also wonder if something like #4 wouldn't compliment something like
the proposed structured logging[1]. I.e. even though we'd like to run
git.git, and present exactly the message to the user we do now, we might
want to run in such a machine-readable mode under the hood when talking
to the server so we can log exactly how the push went / how it failed
for the purposes of aggregation.

1. https://public-inbox.org/git/20180713165621.52017-2-git@jeffhostetler.com/

Re: [PATCH 2/3] archive: implement protocol v2 archive command

[Jonathan Nieder]

Ævar Arnfjörð Bjarmason wrote:
> On Wed, Sep 12 2018, Stefan Beller wrote:

>> Would asking for a setlocale() on the server side be an unreasonable
>> feature request for the capabilities (in a follow up patch, and then not
>> just for archive but also fetch/push, etc.)?
>
> This would be very nice to have, but as you suggest in some follow-up
> change.

Indeed, I think we've gone pretty far afield from the goal of this
patch series.

> I think though that instead of doing setlocale() it would be better to
> pass some flag saying we're operating in a machine-readable mode, and
> then we'd (as part of the protocol defintion) say we're going to emit
> GIT_ERR_UPLOAD_ARCHIVE_EXPECTED_DELIM_PACKET or whatever.

I think you're suggesting client-side message generation, and that is
one way to handle internationalization of server output.

The main downside is when the server really does want to provide a
custom error message.  For that, we'd need

 1. To propagate LANG to the server, so it knows what human language
    to generate messages in.

 2. On the server side, to produce messages in that language if
    available, with an appropriate fallback if not.

We've been thinking of doing at least (1) using the same trick as
server-options use (cramming it into client capabilities).

It is difficult to use setlocale for this because it affects the whole
program (problematic for a threaded server) and affects features like
collation order instead of just message generation (problematic for
many things).  Does gettext have a variant that takes a locale_t
argument?

[...]
>  4) Aside from translation purposes, getting a machine-readable
>     "push/pull" etc. mode would be very handy. E.g. now you need to
>     parse stderr to see why exactly your push failed (hook denied, or
>     non-fast-forward, or non-fast-forward where there was a lock race
>     condition? ...).

Indeed, this is a good reason to provide error codes instead of (in
the case where the message doesn't add anything to it) or alongside
(in case the error message is more specialized) human-oriented error
messages.

Thanks,
Jonathan

Re: [PATCH 2/3] archive: implement protocol v2 archive command

[Ævar Arnfjörð Bjarmason]

On Fri, Sep 14 2018, Jonathan Nieder wrote:

> Ævar Arnfjörð Bjarmason wrote:
>> On Wed, Sep 12 2018, Stefan Beller wrote:
>
>>> Would asking for a setlocale() on the server side be an unreasonable
>>> feature request for the capabilities (in a follow up patch, and then not
>>> just for archive but also fetch/push, etc.)?
>>
>> This would be very nice to have, but as you suggest in some follow-up
>> change.
>
> Indeed, I think we've gone pretty far afield from the goal of this
> patch series.
>
>> I think though that instead of doing setlocale() it would be better to
>> pass some flag saying we're operating in a machine-readable mode, and
>> then we'd (as part of the protocol defintion) say we're going to emit
>> GIT_ERR_UPLOAD_ARCHIVE_EXPECTED_DELIM_PACKET or whatever.
>
> I think you're suggesting client-side message generation, and that is
> one way to handle internationalization of server output.
>
> The main downside is when the server really does want to provide a
> custom error message.  For that, we'd need

Yeah you can't do it for everything. E.g. hooks will want to spew out
custom messages, and this hypothetical protocol extension won't have
codes for those. So you'll still need to pass $LANG along.

>  1. To propagate LANG to the server, so it knows what human language
>     to generate messages in.
>
>  2. On the server side, to produce messages in that language if
>     available, with an appropriate fallback if not.
>
> We've been thinking of doing at least (1) using the same trick as
> server-options use (cramming it into client capabilities).
>
> It is difficult to use setlocale for this because it affects the whole
> program (problematic for a threaded server) and affects features like
> collation order instead of just message generation (problematic for
> many things).  Does gettext have a variant that takes a locale_t
> argument?

No, its API is fairly crappy and depends on setlocale().

Keep in mind though that we're not tied to that API. E.g. one way to
work around this problem is to simply loop through all the languages we
have translations for at server startup, for each one call setlocale()
and gettext(), and save the result in a hash table for runtime lookup,
then you'd just call sprintf(hash[language][message_id], ...) at
runtime.

That's all libintl is really doing under the hood, in a roundabout way
where calls to setlocale() determine what table we're looking things up
in.

The reason I opted to go for gettext to begin with was mainly a) it was
there b) the ubiquitous availability of tooling for translators when it
comes to the *.po files.

But the API for looking things up at runtime is fairly small, and easy
to replace. We could e.g. replace all of our own gettext.[ch] wrapper
with something that works somewhat like what I described above, with
some extra build step to extract the relevant data from the *.mo files
(or parse the *.po directly).

> [...]
>>  4) Aside from translation purposes, getting a machine-readable
>>     "push/pull" etc. mode would be very handy. E.g. now you need to
>>     parse stderr to see why exactly your push failed (hook denied, or
>>     non-fast-forward, or non-fast-forward where there was a lock race
>>     condition? ...).
>
> Indeed, this is a good reason to provide error codes instead of (in
> the case where the message doesn't add anything to it) or alongside
> (in case the error message is more specialized) human-oriented error
> messages.

Re: [PATCH 2/3] archive: implement protocol v2 archive command

[Junio C Hamano]

Jonathan Nieder <jrnieder@gmail.com> writes:

>> I think though that instead of doing setlocale() it would be better to
>> pass some flag saying we're operating in a machine-readable mode, and
>> then we'd (as part of the protocol defintion) say we're going to emit
>> GIT_ERR_UPLOAD_ARCHIVE_EXPECTED_DELIM_PACKET or whatever.
>
> I think you're suggesting client-side message generation, and that is
> one way to handle internationalization of server output.
>
> The main downside is when the server really does want to provide a
> custom error message.  For that, we'd need
>
>  1. To propagate LANG to the server, so it knows what human language
>     to generate messages in.
>
>  2. On the server side, to produce messages in that language if
>     available, with an appropriate fallback if not.

That is one way to do so, but it does not have to be the only way, I
would think.  You can send a machine parsable message in pieces, and
assemble the parts of speech into a message at the receiving end.
Like sending a msgid to identify an entry in the .pot file, and
values to be filled in.

Re: [PATCH 2/3] archive: implement protocol v2 archive command

[Jonathan Nieder]

Junio C Hamano wrote:
> Jonathan Nieder <jrnieder@gmail.com> writes:

>>> I think though that instead of doing setlocale() it would be better to
>>> pass some flag saying we're operating in a machine-readable mode, and
>>> then we'd (as part of the protocol defintion) say we're going to emit
>>> GIT_ERR_UPLOAD_ARCHIVE_EXPECTED_DELIM_PACKET or whatever.
>>
>> I think you're suggesting client-side message generation, and that is
>> one way to handle internationalization of server output.
>>
>> The main downside is when the server really does want to provide a
>> custom error message.  For that, we'd need
>>
>>  1. To propagate LANG to the server, so it knows what human language
>>     to generate messages in.
>>
>>  2. On the server side, to produce messages in that language if
>>     available, with an appropriate fallback if not.
>
> That is one way to do so, but it does not have to be the only way, I
> would think.  You can send a machine parsable message in pieces, and
> assemble the parts of speech into a message at the receiving end.
> Like sending a msgid to identify an entry in the .pot file, and
> values to be filled in.

That works if the same party controls the client and server and the
client is up to date enough to know about every message the server
would want to send.

It doesn't work for
- hooks
- alternate server implementations
- messages involved in an emergency fix
- ... etc ...

Don't get me wrong: for messages with a machine as an audience, error
codes or similar structured errors are a great way to go, and getting
client-side generation of messages for humans (not to mention styling,
etc) are a nice bonus there.  I stand by what's in the message you're
replying to, though: if we actually want to be able to consistently
provide useful messages to people who do not like to read English,
then client-side generation won't get us all the way there.

Jonathan

Re: [PATCH 2/3] archive: implement protocol v2 archive command

[Junio C Hamano]

Josh Steadmon <steadmon@google.com> writes:

> +static int do_v2_command_and_cap(int out)
> +{
> +	packet_write_fmt(out, "command=archive\n");
> +	/* Capability list would go here, if we had any. */
> +	packet_delim(out);
> +}
> +
>  static int run_remote_archiver(int argc, const char **argv,
>  			       const char *remote, const char *exec,
>  			       const char *name_hint)
> @@ -32,6 +41,7 @@ static int run_remote_archiver(int argc, const char **argv,
>  	struct remote *_remote;
>  	struct packet_reader reader;
>  	enum packet_read_status status;
> +	enum protocol_version version;
>  
>  	_remote = remote_get(remote);
>  	if (!_remote->url[0])
> @@ -41,6 +51,11 @@ static int run_remote_archiver(int argc, const char **argv,
>  
>  	packet_reader_init(&reader, fd[0], NULL, 0, PACKET_READ_CHOMP_NEWLINE);
>  
> +	version = discover_version(&reader);

The original version of upload-archive that is correctly running on
the other end sends either NACK (unable to spawn) or ACK (ready to
serve) to us without waiting for us to speak first, so peeking that
with this discover_version() is a safe thing to do.

> +	if (version == protocol_v2)
> +		do_v2_command_and_cap(fd[1]);
> +

With proto v2, "server capabilities" have already been collected in
server_capabilities_v2 array in discover_version().  We are to pick
and ask the capabilities in that function and respond.  Right now we
do not need to do much, as we saw that very thin implementation of
that function above.

>  	/*
>  	 * Inject a fake --format field at the beginning of the
>  	 * arguments, with the format inferred from our output

And then after that, both the original and updated protocol lets us
send the archive format and arguments (like revs and pathspecs),
followed by a flush packet...

> @@ -56,22 +71,24 @@ static int run_remote_archiver(int argc, const char **argv,
>  		packet_write_fmt(fd[1], "argument %s\n", argv[i]);
>  	packet_flush(fd[1]);

... which is a piece of code shared between the protocol versions
that ends here.

> -	status = packet_reader_read(&reader);
> -
> -	if (status == PACKET_READ_FLUSH)
> -		die(_("git archive: expected ACK/NAK, got a flush packet"));
> -	if (strcmp(reader.buffer, "ACK")) {
> -		if (starts_with(reader.buffer, "NACK "))
> -			die(_("git archive: NACK %s"), reader.buffer + 5);
> -		if (starts_with(reader.buffer, "ERR "))
> -			die(_("remote error: %s"), reader.buffer + 4);
> -		die(_("git archive: protocol error"));
> +	if (version == protocol_v0) {
> +		status = packet_reader_read(&reader);
> +
> +		if (status == PACKET_READ_FLUSH)
> +			die(_("git archive: expected ACK/NAK, got a flush packet"));
> +		if (strcmp(reader.buffer, "ACK")) {
> +			if (starts_with(reader.buffer, "NACK "))
> +				die(_("git archive: NACK %s"), reader.buffer + 5);
> +			if (starts_with(reader.buffer, "ERR "))
> +				die(_("remote error: %s"), reader.buffer + 4);
> +			die(_("git archive: protocol error"));
> +		}
> +
> +		status = packet_reader_read(&reader);
> +		if (status != PACKET_READ_FLUSH)
> +			die(_("git archive: expected a flush"));
>  	}

The original protocol lets upload-archive to report failure to spawn
the writer backend process and lets us act on it.  We do not need a
similar support in the updated protocol and instead can jump right
into receiving the archive stream because...?

> -	status = packet_reader_read(&reader);
> -	if (status != PACKET_READ_FLUSH)
> -		die(_("git archive: expected a flush"));
> -

>  	/* Now, start reading from fd[0] and spit it out to stdout */
>  	rv = recv_sideband("archive", fd[0], 1);
>  	rv |= transport_disconnect(transport);



> diff --git a/builtin/upload-archive.c b/builtin/upload-archive.c
> index 25d911635..534e8fd56 100644
> --- a/builtin/upload-archive.c
> +++ b/builtin/upload-archive.c
> @@ -5,6 +5,7 @@
>  #include "builtin.h"
>  #include "archive.h"
>  #include "pkt-line.h"
> +#include "protocol.h"
>  #include "sideband.h"
>  #include "run-command.h"
>  #include "argv-array.h"
> @@ -73,13 +74,53 @@ static ssize_t process_input(int child_fd, int band)
>  	return sz;
>  }
>  
> +static int handle_v2_command_and_cap(void)
> +{
> +	struct packet_reader reader;
> +	enum packet_read_status status;
> +
> +	packet_reader_init(&reader, 0, NULL, 0, PACKET_READ_CHOMP_NEWLINE);
> +
> +	packet_write_fmt(1, "version 2\n");

This lets the discover_version() on the other side notice that we
are speaking version 2.

> +	/*
> +	 * We don't currently send any capabilities, but maybe we could list
> +	 * supported archival formats?
> +	 */
> +	packet_flush(1);

process_capabilities_v2() expects the list of caps ends with a
flush, which is given here.

> +	status = packet_reader_read(&reader);
> +	if (status != PACKET_READ_NORMAL ||
> +	    strcmp(reader.buffer, "command=archive"))
> +		die(_("upload-archive: expected command=archive"));

The other side in do_v2_command_and_cap() would ask command=archive
and that is verified.  _() is unwanted, I suppose, by the way, as
you do not know what language the other side wants anyway.

> +	while (status == PACKET_READ_NORMAL) {
> +		/* We don't currently expect any client capabilities, but we
> +		 * should still read (and ignore) any that happen to get sent.
> +		 */
> +		status = packet_reader_read(&reader);

It is wrong to say we should "ignore".  If you are asked to behave
in a certain way by a capability that is not understood, the other
side expects you to honor that request and you have no idea how to
comply.  At least you should make sure that what is asked is among
the capabilities you offered (or you understand), and you should
error out when you see an unknown one, no?

> +	}
> +	if (status != PACKET_READ_DELIM)
> +		die(_("upload-archive: expected delim packet"));
> +
> +	/* Let git-upload-archive--writer handle the arguments. */

The choice of DELIM here over FLUSH is a bit curious, but it is
consistent between upload-archive and run-remote-archiver.

> +	return 0;
> +}
> +
>  int cmd_upload_archive(int argc, const char **argv, const char *prefix)
>  {
>  	struct child_process writer = { argv };
> +	enum protocol_version version = determine_protocol_version_server();
>  
>  	if (argc == 2 && !strcmp(argv[1], "-h"))
>  		usage(upload_archive_usage);
>  
> +	if (version == protocol_v2)
> +		handle_v2_command_and_cap();
> +	else {
> +		packet_write_fmt(1, "ACK\n");
> +		packet_flush(1);
> +	}
> +

This breaks the original protocol, no?  At this point we haven't
even tried to start the writer process, and letting the other side
go by giving ACK + flush prematurely.  After start_command() fails,
we may say NACK, but the other side is no longer listening to it.

>  	/*
>  	 * Set up sideband subprocess.
>  	 *
> @@ -96,9 +137,6 @@ int cmd_upload_archive(int argc, const char **argv, const char *prefix)
>  		die("upload-archive: %s", strerror(err));
>  	}
>  
> -	packet_write_fmt(1, "ACK\n");
> -	packet_flush(1);
> -
>  	while (1) {
>  		struct pollfd pfd[2];
>  
> diff --git a/t/t5000-tar-tree.sh b/t/t5000-tar-tree.sh
> index 2a97b27b0..4be74d6e9 100755
> --- a/t/t5000-tar-tree.sh
> +++ b/t/t5000-tar-tree.sh
> @@ -145,6 +145,11 @@ test_expect_success \
>  
>  check_tar b
>  
> +test_expect_success 'protocol v2 for remote' '
> +	GIT_PROTOCOL="version=2" git archive --remote=. HEAD >v2_remote.tar
> +'
> +check_tar v2_remote
> +
>  test_expect_success 'git archive --prefix=prefix/' '
>  	git archive --prefix=prefix/ HEAD >with_prefix.tar
>  '

Re: [PATCH 2/3] archive: implement protocol v2 archive command

[Jonathan Nieder]

Hi,

Josh Steadmon wrote:

> This adds a new archive command for protocol v2. The command expects
> arguments in the form "argument X" which are passed unmodified to
> git-upload-archive--writer.
>
> This command works over the file://, Git, and SSH transports. HTTP
> support will be added in a separate patch.
>
> Signed-off-by: Josh Steadmon <steadmon@google.com>
> ---
>  builtin/archive.c        | 45 +++++++++++++++++++++++++++-------------
>  builtin/upload-archive.c | 44 ++++++++++++++++++++++++++++++++++++---
>  t/t5000-tar-tree.sh      |  5 +++++
>  3 files changed, 77 insertions(+), 17 deletions(-)

I like the diffstat. :)

Can this include some docs in Documentation/technical/ as well, to
help other implementors to understand the protocol so they can
interoperate?

Thanks,
Jonathan

[PATCH 3/3] archive: allow archive over HTTP(S) with proto v2

[Josh Steadmon]

Signed-off-by: Josh Steadmon <steadmon@google.com>
---
 builtin/archive.c  |  8 +++++++-
 http-backend.c     | 10 +++++++++-
 transport-helper.c |  5 +++--
 3 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/builtin/archive.c b/builtin/archive.c
index 73831887d..5fa75b3f7 100644
--- a/builtin/archive.c
+++ b/builtin/archive.c
@@ -87,7 +87,13 @@ static int run_remote_archiver(int argc, const char **argv,
 		status = packet_reader_read(&reader);
 		if (status != PACKET_READ_FLUSH)
 			die(_("git archive: expected a flush"));
-	}
+	} else if (version == protocol_v2 &&
+		   starts_with(transport->url, "http"))
+		/*
+		 * Commands over HTTP require two requests, so there's an
+		 * additional server response to parse.
+		 */
+		discover_version(&reader);
 
 	/* Now, start reading from fd[0] and spit it out to stdout */
 	rv = recv_sideband("archive", fd[0], 1);
diff --git a/http-backend.c b/http-backend.c
index 458642ef7..d62d583c7 100644
--- a/http-backend.c
+++ b/http-backend.c
@@ -32,6 +32,7 @@ struct rpc_service {
 static struct rpc_service rpc_service[] = {
 	{ "upload-pack", "uploadpack", 1, 1 },
 	{ "receive-pack", "receivepack", 0, -1 },
+	{ "upload-archive", "uploadarchive", 1, 1 },
 };
 
 static struct string_list *get_parameters(void)
@@ -637,6 +638,12 @@ static void service_rpc(struct strbuf *hdr, char *service_name)
 	struct rpc_service *svc = select_service(hdr, service_name);
 	struct strbuf buf = STRBUF_INIT;
 
+	if (!strcmp(service_name, "git-upload-archive")) {
+		/* git-upload-archive doesn't need --stateless-rpc */
+		argv[1] = ".";
+		argv[2] = NULL;
+	}
+
 	strbuf_reset(&buf);
 	strbuf_addf(&buf, "application/x-git-%s-request", svc->name);
 	check_content_type(hdr, buf.buf);
@@ -713,7 +720,8 @@ static struct service_cmd {
 	{"GET", "/objects/pack/pack-[0-9a-f]{40}\\.idx$", get_idx_file},
 
 	{"POST", "/git-upload-pack$", service_rpc},
-	{"POST", "/git-receive-pack$", service_rpc}
+	{"POST", "/git-receive-pack$", service_rpc},
+	{"POST", "/git-upload-archive$", service_rpc},
 };
 
 static int bad_request(struct strbuf *hdr, const struct service_cmd *c)
diff --git a/transport-helper.c b/transport-helper.c
index 143ca008c..b4b96fc89 100644
--- a/transport-helper.c
+++ b/transport-helper.c
@@ -605,7 +605,8 @@ static int process_connect_service(struct transport *transport,
 		ret = run_connect(transport, &cmdbuf);
 	} else if (data->stateless_connect &&
 		   (get_protocol_version_config() == protocol_v2) &&
-		   !strcmp("git-upload-pack", name)) {
+		   (!strcmp("git-upload-pack", name) ||
+		    !strcmp("git-upload-archive", name))) {
 		strbuf_addf(&cmdbuf, "stateless-connect %s\n", name);
 		ret = run_connect(transport, &cmdbuf);
 		if (ret)
@@ -639,7 +640,7 @@ static int connect_helper(struct transport *transport, const char *name,
 
 	/* Get_helper so connect is inited. */
 	get_helper(transport);
-	if (!data->connect)
+	if (!data->connect && !data->stateless_connect)
 		die(_("operation not supported by protocol"));
 
 	if (!process_connect_service(transport, name, exec))
-- 
2.19.0.397.gdd90340f6a-goog

Re: [PATCH 3/3] archive: allow archive over HTTP(S) with proto v2

[Stefan Beller]

On Tue, Sep 11, 2018 at 10:36 PM Josh Steadmon <steadmon@google.com> wrote:
>
> Signed-off-by: Josh Steadmon <steadmon@google.com>
> ---
>  builtin/archive.c  |  8 +++++++-
>  http-backend.c     | 10 +++++++++-
>  transport-helper.c |  5 +++--
>  3 files changed, 19 insertions(+), 4 deletions(-)
>
> diff --git a/builtin/archive.c b/builtin/archive.c
> index 73831887d..5fa75b3f7 100644
> --- a/builtin/archive.c
> +++ b/builtin/archive.c
> @@ -87,7 +87,13 @@ static int run_remote_archiver(int argc, const char **argv,
>                 status = packet_reader_read(&reader);
>                 if (status != PACKET_READ_FLUSH)
>                         die(_("git archive: expected a flush"));
> -       }
> +       } else if (version == protocol_v2 &&
> +                  starts_with(transport->url, "http"))

I assume this is a smart way to cover both http and https
as the latter is prefixed by the former.

How does this interact with remote helpers
(See gitremote-helpers(1), which doesn't mention archives,
but I would imagine that one would be able to use a remote
helper eventually, too?

    git archive --remote=abc://example.org/test ....

> +               /*
> +                * Commands over HTTP require two requests, so there's an
> +                * additional server response to parse.
> +                */
> +               discover_version(&reader);
>
>         /* Now, start reading from fd[0] and spit it out to stdout */
>         rv = recv_sideband("archive", fd[0], 1);
> diff --git a/http-backend.c b/http-backend.c
> index 458642ef7..d62d583c7 100644
> --- a/http-backend.c
> +++ b/http-backend.c
> @@ -32,6 +32,7 @@ struct rpc_service {
>  static struct rpc_service rpc_service[] = {
>         { "upload-pack", "uploadpack", 1, 1 },
>         { "receive-pack", "receivepack", 0, -1 },
> +       { "upload-archive", "uploadarchive", 1, 1 },

So git archives are not supported in protocol v0 via http?
Then it makes sense to see not mention of archives in
the remote helpers as well.

The rest of the code is a surprisingly small patch.

Stefan

Re: [PATCH 3/3] archive: allow archive over HTTP(S) with proto v2

[Junio C Hamano]

Josh Steadmon <steadmon@google.com> writes:

> Signed-off-by: Josh Steadmon <steadmon@google.com>
> ---
>  builtin/archive.c  |  8 +++++++-
>  http-backend.c     | 10 +++++++++-
>  transport-helper.c |  5 +++--
>  3 files changed, 19 insertions(+), 4 deletions(-)
>
> diff --git a/builtin/archive.c b/builtin/archive.c
> index 73831887d..5fa75b3f7 100644
> --- a/builtin/archive.c
> +++ b/builtin/archive.c
> @@ -87,7 +87,13 @@ static int run_remote_archiver(int argc, const char **argv,
>  		status = packet_reader_read(&reader);
>  		if (status != PACKET_READ_FLUSH)
>  			die(_("git archive: expected a flush"));
> -	}
> +	} else if (version == protocol_v2 &&
> +		   starts_with(transport->url, "http"))
> +		/*
> +		 * Commands over HTTP require two requests, so there's an
> +		 * additional server response to parse.
> +		 */
> +		discover_version(&reader);

What should happen if the version discovered here is different from
v2 or the capabilities offered are different from what we saw
before?  Perhaps we need some sanity checks, as we on this side of
the connection know we are making two requests, and may even end up
talking with an instance of "upload-archive" that is different from
the one we talked with earlier.

> diff --git a/http-backend.c b/http-backend.c
> index 458642ef7..d62d583c7 100644
> --- a/http-backend.c
> +++ b/http-backend.c
> @@ -32,6 +32,7 @@ struct rpc_service {
>  static struct rpc_service rpc_service[] = {
>  	{ "upload-pack", "uploadpack", 1, 1 },
>  	{ "receive-pack", "receivepack", 0, -1 },
> +	{ "upload-archive", "uploadarchive", 1, 1 },
>  };
>  
>  static struct string_list *get_parameters(void)
> @@ -637,6 +638,12 @@ static void service_rpc(struct strbuf *hdr, char *service_name)
>  	struct rpc_service *svc = select_service(hdr, service_name);
>  	struct strbuf buf = STRBUF_INIT;
>  
> +	if (!strcmp(service_name, "git-upload-archive")) {
> +		/* git-upload-archive doesn't need --stateless-rpc */
> +		argv[1] = ".";
> +		argv[2] = NULL;
> +	}
> +
>  	strbuf_reset(&buf);
>  	strbuf_addf(&buf, "application/x-git-%s-request", svc->name);
>  	check_content_type(hdr, buf.buf);
> @@ -713,7 +720,8 @@ static struct service_cmd {
>  	{"GET", "/objects/pack/pack-[0-9a-f]{40}\\.idx$", get_idx_file},
>  
>  	{"POST", "/git-upload-pack$", service_rpc},
> -	{"POST", "/git-receive-pack$", service_rpc}
> +	{"POST", "/git-receive-pack$", service_rpc},
> +	{"POST", "/git-upload-archive$", service_rpc},
>  };
>  
>  static int bad_request(struct strbuf *hdr, const struct service_cmd *c)
> diff --git a/transport-helper.c b/transport-helper.c
> index 143ca008c..b4b96fc89 100644
> --- a/transport-helper.c
> +++ b/transport-helper.c
> @@ -605,7 +605,8 @@ static int process_connect_service(struct transport *transport,
>  		ret = run_connect(transport, &cmdbuf);
>  	} else if (data->stateless_connect &&
>  		   (get_protocol_version_config() == protocol_v2) &&
> -		   !strcmp("git-upload-pack", name)) {
> +		   (!strcmp("git-upload-pack", name) ||
> +		    !strcmp("git-upload-archive", name))) {
>  		strbuf_addf(&cmdbuf, "stateless-connect %s\n", name);
>  		ret = run_connect(transport, &cmdbuf);
>  		if (ret)
> @@ -639,7 +640,7 @@ static int connect_helper(struct transport *transport, const char *name,
>  
>  	/* Get_helper so connect is inited. */
>  	get_helper(transport);
> -	if (!data->connect)
> +	if (!data->connect && !data->stateless_connect)
>  		die(_("operation not supported by protocol"));

This is somewhat curious.  The upload-pack going over HTTP also is
triggered by the same "stateless-connect" remote helper command, as
we just saw in the previous hunk, and that support is not new.  Why
do we need this change then?  What's different between the "data"
that is obtained by get_helper(transport) for driving upload-pack
and upload-archive?  Presumably upload-pack was working without this
change because it also sets the connect bit on, and upload-archive
does not work without this change because it does not?  Why do these
two behave differently?

>  	if (!process_connect_service(transport, name, exec))

Re: [PATCH 3/3] archive: allow archive over HTTP(S) with proto v2

[Josh Steadmon]

On 2018.09.13 09:47, Junio C Hamano wrote:
> Josh Steadmon <steadmon@google.com> writes:
> 
> > Signed-off-by: Josh Steadmon <steadmon@google.com>
> > ---
> >  builtin/archive.c  |  8 +++++++-
> >  http-backend.c     | 10 +++++++++-
> >  transport-helper.c |  5 +++--
> >  3 files changed, 19 insertions(+), 4 deletions(-)
> >
> > diff --git a/builtin/archive.c b/builtin/archive.c
> > index 73831887d..5fa75b3f7 100644
> > --- a/builtin/archive.c
> > +++ b/builtin/archive.c
> > @@ -87,7 +87,13 @@ static int run_remote_archiver(int argc, const char **argv,
> >  		status = packet_reader_read(&reader);
> >  		if (status != PACKET_READ_FLUSH)
> >  			die(_("git archive: expected a flush"));
> > -	}
> > +	} else if (version == protocol_v2 &&
> > +		   starts_with(transport->url, "http"))
> > +		/*
> > +		 * Commands over HTTP require two requests, so there's an
> > +		 * additional server response to parse.
> > +		 */
> > +		discover_version(&reader);
> 
> What should happen if the version discovered here is different from
> v2 or the capabilities offered are different from what we saw
> before?  Perhaps we need some sanity checks, as we on this side of
> the connection know we are making two requests, and may even end up
> talking with an instance of "upload-archive" that is different from
> the one we talked with earlier.
> 
> > diff --git a/http-backend.c b/http-backend.c
> > index 458642ef7..d62d583c7 100644
> > --- a/http-backend.c
> > +++ b/http-backend.c
> > @@ -32,6 +32,7 @@ struct rpc_service {
> >  static struct rpc_service rpc_service[] = {
> >  	{ "upload-pack", "uploadpack", 1, 1 },
> >  	{ "receive-pack", "receivepack", 0, -1 },
> > +	{ "upload-archive", "uploadarchive", 1, 1 },
> >  };
> >  
> >  static struct string_list *get_parameters(void)
> > @@ -637,6 +638,12 @@ static void service_rpc(struct strbuf *hdr, char *service_name)
> >  	struct rpc_service *svc = select_service(hdr, service_name);
> >  	struct strbuf buf = STRBUF_INIT;
> >  
> > +	if (!strcmp(service_name, "git-upload-archive")) {
> > +		/* git-upload-archive doesn't need --stateless-rpc */
> > +		argv[1] = ".";
> > +		argv[2] = NULL;
> > +	}
> > +
> >  	strbuf_reset(&buf);
> >  	strbuf_addf(&buf, "application/x-git-%s-request", svc->name);
> >  	check_content_type(hdr, buf.buf);
> > @@ -713,7 +720,8 @@ static struct service_cmd {
> >  	{"GET", "/objects/pack/pack-[0-9a-f]{40}\\.idx$", get_idx_file},
> >  
> >  	{"POST", "/git-upload-pack$", service_rpc},
> > -	{"POST", "/git-receive-pack$", service_rpc}
> > +	{"POST", "/git-receive-pack$", service_rpc},
> > +	{"POST", "/git-upload-archive$", service_rpc},
> >  };
> >  
> >  static int bad_request(struct strbuf *hdr, const struct service_cmd *c)
> > diff --git a/transport-helper.c b/transport-helper.c
> > index 143ca008c..b4b96fc89 100644
> > --- a/transport-helper.c
> > +++ b/transport-helper.c
> > @@ -605,7 +605,8 @@ static int process_connect_service(struct transport *transport,
> >  		ret = run_connect(transport, &cmdbuf);
> >  	} else if (data->stateless_connect &&
> >  		   (get_protocol_version_config() == protocol_v2) &&
> > -		   !strcmp("git-upload-pack", name)) {
> > +		   (!strcmp("git-upload-pack", name) ||
> > +		    !strcmp("git-upload-archive", name))) {
> >  		strbuf_addf(&cmdbuf, "stateless-connect %s\n", name);
> >  		ret = run_connect(transport, &cmdbuf);
> >  		if (ret)
> > @@ -639,7 +640,7 @@ static int connect_helper(struct transport *transport, const char *name,
> >  
> >  	/* Get_helper so connect is inited. */
> >  	get_helper(transport);
> > -	if (!data->connect)
> > +	if (!data->connect && !data->stateless_connect)
> >  		die(_("operation not supported by protocol"));
> 
> This is somewhat curious.  The upload-pack going over HTTP also is
> triggered by the same "stateless-connect" remote helper command, as
> we just saw in the previous hunk, and that support is not new.  Why
> do we need this change then?  What's different between the "data"
> that is obtained by get_helper(transport) for driving upload-pack
> and upload-archive?  Presumably upload-pack was working without this
> change because it also sets the connect bit on, and upload-archive
> does not work without this change because it does not?  Why do these
> two behave differently?

The data struct is not different between upload-pack vs. upload-archive.
Neither of them set the connect bit. The difference is that upload-pack
doesn't need to call transport_connect(), so it never hits
connect_helper().

Re: [PATCH 3/3] archive: allow archive over HTTP(S) with proto v2

[Jonathan Nieder]

Hi,

Josh Steadmon wrote:

> Subject: archive: allow archive over HTTP(S) with proto v2

It's interesting how little this has to touch the client.

> Signed-off-by: Josh Steadmon <steadmon@google.com>
> ---
>  builtin/archive.c  |  8 +++++++-
>  http-backend.c     | 10 +++++++++-
>  transport-helper.c |  5 +++--
>  3 files changed, 19 insertions(+), 4 deletions(-)
[....]
> --- a/builtin/archive.c
> +++ b/builtin/archive.c
> @@ -87,7 +87,13 @@ static int run_remote_archiver(int argc, const char **argv,
>  		status = packet_reader_read(&reader);
>  		if (status != PACKET_READ_FLUSH)
>  			die(_("git archive: expected a flush"));
> -	}
> +	} else if (version == protocol_v2 &&
> +		   starts_with(transport->url, "http"))

As Stefan noticed, this starts_with test seems a bit too loose.  For
example, what happens if I try an scp-style SSH URL like
http.example.com:path/to/repo, a local path like http/foo/bar, or a
custom protocol like httplikebutbetter://path/to/repo (honest
question: I haven't tried)?

> +		/*
> +		 * Commands over HTTP require two requests, so there's an
> +		 * additional server response to parse.
> +		 */
> +		discover_version(&reader);

Can this be made consistent with the non-http case?  The original
capabilities (/info/refs) response told us what protocol version the
server wants to use, which means that a hypothetical protocol v3 could
use a completely different request format for the followup commands:
so could the server omit the protocol version in the v2
/git-upload-archive response?  Alternatively, if we want to include
the protocol version again, could we do that in stateful protocols as
well?

Related question: what should happen if the two responses declare
different protocol versions?  Should we diagnose that as a protocol
error?

[...]
> --- a/http-backend.c
> +++ b/http-backend.c
> @@ -32,6 +32,7 @@ struct rpc_service {
>  static struct rpc_service rpc_service[] = {
>  	{ "upload-pack", "uploadpack", 1, 1 },
>  	{ "receive-pack", "receivepack", 0, -1 },
> +	{ "upload-archive", "uploadarchive", 1, 1 },

shell.c orders these in almost-alphabetical order (receive-pack,
upload-pack, upload-archive).  I guess they should both use actual
alphabetical order?  (If you agree, then please feel free to do that
in a separate patch.)

[...]
> @@ -637,6 +638,12 @@ static void service_rpc(struct strbuf *hdr, char *service_name)
>  	struct rpc_service *svc = select_service(hdr, service_name);
>  	struct strbuf buf = STRBUF_INIT;
>  
> +	if (!strcmp(service_name, "git-upload-archive")) {
> +		/* git-upload-archive doesn't need --stateless-rpc */

This comment doesn't seem actionable.  Can it say why?  E.g. "[...]
because an upload-archive command always involves a single
round-trip".  Or alternatively, I think it's fine to omit the comment.

> +		argv[1] = ".";
> +		argv[2] = NULL;
> +	}
[...]
> @@ -713,7 +720,8 @@ static struct service_cmd {
>  	{"GET", "/objects/pack/pack-[0-9a-f]{40}\\.idx$", get_idx_file},
>  
>  	{"POST", "/git-upload-pack$", service_rpc},
> -	{"POST", "/git-receive-pack$", service_rpc}
> +	{"POST", "/git-receive-pack$", service_rpc},
> +	{"POST", "/git-upload-archive$", service_rpc},

Same comment about services seeming to be in a randomish order.

[...]
> --- a/transport-helper.c
> +++ b/transport-helper.c
> @@ -605,7 +605,8 @@ static int process_connect_service(struct transport *transport,
>  		ret = run_connect(transport, &cmdbuf);
>  	} else if (data->stateless_connect &&
>  		   (get_protocol_version_config() == protocol_v2) &&

(not about this patch) These parens don't help --- they make it harder
for me to read, especially with the new parens to try to match them up
with.

> -		   !strcmp("git-upload-pack", name)) {
> +		   (!strcmp("git-upload-pack", name) ||
> +		    !strcmp("git-upload-archive", name))) {

A part of me wonders about the wasted cycles comparing to
"git-upload-" twice, but (1) it is tiny relative to actually serving
the request and (2) if we're lucky, the compiler (or a compiler of the
future) inlines the strcmp call and could optimize it out.

[...]
> @@ -639,7 +640,7 @@ static int connect_helper(struct transport *transport, const char *name,
>  
>  	/* Get_helper so connect is inited. */
>  	get_helper(transport);
> -	if (!data->connect)
> +	if (!data->connect && !data->stateless_connect)
>  		die(_("operation not supported by protocol"));

I don't understand this part.  Can you explain it further (possibly by
putting it in its own patch)?

Thanks for a pleasant read,
Jonathan

Re: Add proto v2 archive command with HTTP support

[Jonathan Nieder]

Hi,

Josh Steadmon wrote:

> This series adds a new protocol v2 command for archiving, and allows
> this command to work over HTTP(S). This was previously discussed in [1].
> I've CCed everyone who participated in that discussion.

Yay!  Getting ready to read it now.

For the future, "git format-patch --cover-letter" does a few things
that can be nice for this kind of opening message:

- it lists the patches in the series, and a diffstat
- it puts [PATCH 0/3] in the subject line so people know what to expect

Thanks,
Jonathan

> [1]: https://public-inbox.org/git/CANq=j3tK7QeBJOC7VNWkh4+WBNibMJJp5YUkd9te5NaYwukAow@mail.gmail.com/

[PATCH v2 0/4] Add proto v2 archive command with HTTP support

[Josh Steadmon]

This is the second version of my series to add a new protocol v2 command
for archiving, with support for HTTP(S).

NEEDSWORK: a server built with this series is not backwards-compatible
with clients that set GIT_PROTOCOL=version=2 or configure
protocol.version=2. The old client will unconditionally send "argument
..." packet lines, which breaks the server's expectations of a
"command=archive" request, while the server's capability advertisement
in turn breaks the clients expectation of either an ACK or NACK.

I've been discussing workarounds for this with Jonathan Nieder, but
please let me know if you have any suggestions for v3 of this series.


Josh Steadmon (4):
  archive: follow test standards around assertions
  archive: use packet_reader for communications
  archive: implement protocol v2 archive command
  archive: allow archive over HTTP(S) with proto v2

 Documentation/technical/protocol-v2.txt | 21 ++++++++-
 builtin/archive.c                       | 58 +++++++++++++++++++------
 builtin/upload-archive.c                | 27 ++++++++++--
 http-backend.c                          | 13 +++++-
 serve.c                                 |  7 +++
 t/t5000-tar-tree.sh                     | 33 +++++++-------
 t/t5701-git-serve.sh                    |  1 +
 transport-helper.c                      |  7 +--
 8 files changed, 130 insertions(+), 37 deletions(-)

Range-diff against v1:
-:  ---------- > 1:  c2e371ad24 archive: follow test standards around assertions
1:  b514184273 ! 2:  a65f73f627 archive: use packet_reader for communications
    @@ -6,7 +6,10 @@
         handling, which will make implementation of protocol v2 support in
         git-archive easier.
     
    +    This refactoring does not change the behavior of "git archive".
    +
         Signed-off-by: Josh Steadmon <steadmon@google.com>
    +    Reviewed-by: Stefan Beller <sbeller@google.com>
     
      diff --git a/builtin/archive.c b/builtin/archive.c
    @@ -42,24 +45,24 @@
     -	if (!buf)
     +	status = packet_reader_read(&reader);
     +
    -+	if (status == PACKET_READ_FLUSH)
    ++	if (status != PACKET_READ_NORMAL || reader.pktlen <= 0)
      		die(_("git archive: expected ACK/NAK, got a flush packet"));
     -	if (strcmp(buf, "ACK")) {
     -		if (starts_with(buf, "NACK "))
     -			die(_("git archive: NACK %s"), buf + 5);
     -		if (starts_with(buf, "ERR "))
     -			die(_("remote error: %s"), buf + 4);
    -+	if (strcmp(reader.buffer, "ACK")) {
    -+		if (starts_with(reader.buffer, "NACK "))
    -+			die(_("git archive: NACK %s"), reader.buffer + 5);
    -+		if (starts_with(reader.buffer, "ERR "))
    -+			die(_("remote error: %s"), reader.buffer + 4);
    ++	if (strcmp(reader.line, "ACK")) {
    ++		if (starts_with(reader.line, "NACK "))
    ++			die(_("git archive: NACK %s"), reader.line + 5);
    ++		if (starts_with(reader.line, "ERR "))
    ++			die(_("remote error: %s"), reader.line + 4);
      		die(_("git archive: protocol error"));
      	}
      
     -	if (packet_read_line(fd[0], NULL))
     +	status = packet_reader_read(&reader);
    -+	if (status != PACKET_READ_FLUSH)
    ++	if (status == PACKET_READ_NORMAL && reader.pktlen > 0)
      		die(_("git archive: expected a flush"));
      
      	/* Now, start reading from fd[0] and spit it out to stdout */
2:  1518c15dc1 < -:  ---------- archive: implement protocol v2 archive command
-:  ---------- > 3:  0a8cc5e331 archive: implement protocol v2 archive command
3:  1b7ad8d8f6 ! 4:  97a1424f32 archive: allow archive over HTTP(S) with proto v2
    @@ -10,16 +10,20 @@
      +++ b/builtin/archive.c
     @@
      		status = packet_reader_read(&reader);
    - 		if (status != PACKET_READ_FLUSH)
    + 		if (status == PACKET_READ_NORMAL && reader.pktlen > 0)
      			die(_("git archive: expected a flush"));
     -	}
     +	} else if (version == protocol_v2 &&
    -+		   starts_with(transport->url, "http"))
    ++		   (starts_with(transport->url, "http://") ||
    ++		    starts_with(transport->url, "https://")))
     +		/*
     +		 * Commands over HTTP require two requests, so there's an
    -+		 * additional server response to parse.
    ++		 * additional server response to parse. We do only basic sanity
    ++		 * checking here that the versions presented match across
    ++		 * requests.
     +		 */
    -+		discover_version(&reader);
    ++		if (version != discover_version(&reader))
    ++			die(_("git archive: received different protocol versions in subsequent requests"));
      
      	/* Now, start reading from fd[0] and spit it out to stdout */
      	rv = recv_sideband("archive", fd[0], 1);
    @@ -40,7 +44,10 @@
      	struct strbuf buf = STRBUF_INIT;
      
     +	if (!strcmp(service_name, "git-upload-archive")) {
    -+		/* git-upload-archive doesn't need --stateless-rpc */
    ++		/*
    ++		 * git-upload-archive doesn't need --stateless-rpc, because it
    ++		 * always handles only a single request.
    ++		 */
     +		argv[1] = ".";
     +		argv[2] = NULL;
     +	}
    @@ -63,10 +70,12 @@
      --- a/transport-helper.c
      +++ b/transport-helper.c
     @@
    + 		strbuf_addf(&cmdbuf, "connect %s\n", name);
      		ret = run_connect(transport, &cmdbuf);
      	} else if (data->stateless_connect &&
    - 		   (get_protocol_version_config() == protocol_v2) &&
    +-		   (get_protocol_version_config() == protocol_v2) &&
     -		   !strcmp("git-upload-pack", name)) {
    ++		   get_protocol_version_config() == protocol_v2 &&
     +		   (!strcmp("git-upload-pack", name) ||
     +		    !strcmp("git-upload-archive", name))) {
      		strbuf_addf(&cmdbuf, "stateless-connect %s\n", name);
-- 
2.19.0.605.g01d371f741-goog

[PATCH v2 1/4] archive: follow test standards around assertions

[Josh Steadmon]

Move assertions outside of the check_tar function so that all top-level
code is wrapped in a test_expect_* assertion.

Signed-off-by: Josh Steadmon <steadmon@google.com>
---
 t/t5000-tar-tree.sh | 26 ++++++++++----------------
 1 file changed, 10 insertions(+), 16 deletions(-)

diff --git a/t/t5000-tar-tree.sh b/t/t5000-tar-tree.sh
index 2a97b27b0a..c408e3a23d 100755
--- a/t/t5000-tar-tree.sh
+++ b/t/t5000-tar-tree.sh
@@ -62,11 +62,9 @@ check_tar() {
 	dir=$1
 	dir_with_prefix=$dir/$2
 
-	test_expect_success ' extract tar archive' '
-		(mkdir $dir && cd $dir && "$TAR" xf -) <$tarfile
-	'
+	(mkdir $dir && cd $dir && "$TAR" xf -) <$tarfile &&
 
-	test_expect_success TAR_NEEDS_PAX_FALLBACK ' interpret pax headers' '
+	if test_have_prereq TAR_NEEDS_PAX_FALLBACK ; then
 		(
 			cd $dir &&
 			for header in *.paxheader
@@ -82,16 +80,11 @@ check_tar() {
 				fi
 			done
 		)
-	'
+	fi &&
 
-	test_expect_success ' validate filenames' '
-		(cd ${dir_with_prefix}a && find .) | sort >$listfile &&
-		test_cmp a.lst $listfile
-	'
-
-	test_expect_success ' validate file contents' '
-		diff -r a ${dir_with_prefix}a
-	'
+	(cd ${dir_with_prefix}a && find .) | sort >$listfile &&
+	test_cmp a.lst $listfile &&
+	diff -r a ${dir_with_prefix}a
 }
 
 test_expect_success \
@@ -143,19 +136,20 @@ test_expect_success \
     'git archive' \
     'git archive HEAD >b.tar'
 
-check_tar b
+test_expect_success 'extract archive' 'check_tar b'
 
 test_expect_success 'git archive --prefix=prefix/' '
 	git archive --prefix=prefix/ HEAD >with_prefix.tar
 '
 
-check_tar with_prefix prefix/
+test_expect_success 'extract with prefix' 'check_tar with_prefix prefix/'
 
 test_expect_success 'git-archive --prefix=olde-' '
 	git archive --prefix=olde- HEAD >with_olde-prefix.tar
 '
 
-check_tar with_olde-prefix olde-
+test_expect_success 'extract with olde- prefix' \
+	'check_tar with_olde-prefix olde-'
 
 test_expect_success 'git archive on large files' '
     test_config core.bigfilethreshold 1 &&
-- 
2.19.0.605.g01d371f741-goog

Re: [PATCH v2 1/4] archive: follow test standards around assertions

[Stefan Beller]

On Wed, Sep 26, 2018 at 6:25 PM Josh Steadmon <steadmon@google.com> wrote:
>
> Move assertions outside of the check_tar function so that all top-level
> code is wrapped in a test_expect_* assertion.

Cool, I'll file this under modernizing the test infrastructure ;-)

> diff --git a/t/t5000-tar-tree.sh b/t/t5000-tar-tree.sh
> index 2a97b27b0a..c408e3a23d 100755
> --- a/t/t5000-tar-tree.sh
> +++ b/t/t5000-tar-tree.sh
> @@ -62,11 +62,9 @@ check_tar() {
>         dir=$1
>         dir_with_prefix=$dir/$2
>
> -       test_expect_success ' extract tar archive' '
> -               (mkdir $dir && cd $dir && "$TAR" xf -) <$tarfile
> -       '
> +       (mkdir $dir && cd $dir && "$TAR" xf -) <$tarfile &&
>
> -       test_expect_success TAR_NEEDS_PAX_FALLBACK ' interpret pax headers' '
> +       if test_have_prereq TAR_NEEDS_PAX_FALLBACK ; then
>                 (
>                         cd $dir &&
>                         for header in *.paxheader
> @@ -82,16 +80,11 @@ check_tar() {
>                                 fi
>                         done
>                 )
> -       '
> +       fi &&
>
> -       test_expect_success ' validate filenames' '
> -               (cd ${dir_with_prefix}a && find .) | sort >$listfile &&
> -               test_cmp a.lst $listfile
> -       '
> -
> -       test_expect_success ' validate file contents' '
> -               diff -r a ${dir_with_prefix}a
> -       '
> +       (cd ${dir_with_prefix}a && find .) | sort >$listfile &&
> +       test_cmp a.lst $listfile &&
> +       diff -r a ${dir_with_prefix}a

Up to here we unwrapped code and removed test_expect_success
and just executed the code as is, so later callers would need to encapsulate
the call to check_tar with test_expect_success.

However as we are touching the code here, we can go further than just
unwrapping it, usually we'd format one command a line,

    (
        cd ${dir_with_prefix}a &&
        find .
    ) | sort >$listfile &&
    test_cmp ...

I am not sure if that standard style is more legible in this case though.

>  }
>
>  test_expect_success \
> @@ -143,19 +136,20 @@ test_expect_success \
>      'git archive' \
>      'git archive HEAD >b.tar'
>
> -check_tar b
> +test_expect_success 'extract archive' 'check_tar b'

Heh. Just looked into the file and the surrounding code is
a wild mixture of the old style

test_expect_success \
    'git archive' \
    'git archive HEAD >b.tar'

check_tar b

and the new style

test_expect_success 'test name' '
 <TAB> command &&
 <TAB> command2
'

Maybe we could cleanup that file to look more like
one of the newer tests (e.g. t3206, t0410) ?

But I guess for the purpose of getting the check_tar
function usable inside a test, this would do enough.

>
>  test_expect_success 'git archive --prefix=prefix/' '
>         git archive --prefix=prefix/ HEAD >with_prefix.tar
>  '
>
> -check_tar with_prefix prefix/
> +test_expect_success 'extract with prefix' 'check_tar with_prefix prefix/'
>
>  test_expect_success 'git-archive --prefix=olde-' '
>         git archive --prefix=olde- HEAD >with_olde-prefix.tar
>  '
>
> -check_tar with_olde-prefix olde-
> +test_expect_success 'extract with olde- prefix' \
> +       'check_tar with_olde-prefix olde-'

In new style this would look like

    test_expect_success 'extract with olde- prefix' '
        check_tar with_olde-prefix olde-
    '

[PATCH v2 2/4] archive: use packet_reader for communications

[Josh Steadmon]

Using packet_reader will simplify version detection and capability
handling, which will make implementation of protocol v2 support in
git-archive easier.

This refactoring does not change the behavior of "git archive".

Signed-off-by: Josh Steadmon <steadmon@google.com>
---
 builtin/archive.c | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/builtin/archive.c b/builtin/archive.c
index e74f675390..4eb547c5b7 100644
--- a/builtin/archive.c
+++ b/builtin/archive.c
@@ -27,10 +27,11 @@ static int run_remote_archiver(int argc, const char **argv,
 			       const char *remote, const char *exec,
 			       const char *name_hint)
 {
-	char *buf;
 	int fd[2], i, rv;
 	struct transport *transport;
 	struct remote *_remote;
+	struct packet_reader reader;
+	enum packet_read_status status;
 
 	_remote = remote_get(remote);
 	if (!_remote->url[0])
@@ -38,6 +39,8 @@ static int run_remote_archiver(int argc, const char **argv,
 	transport = transport_get(_remote, _remote->url[0]);
 	transport_connect(transport, "git-upload-archive", exec, fd);
 
+	packet_reader_init(&reader, fd[0], NULL, 0, PACKET_READ_CHOMP_NEWLINE);
+
 	/*
 	 * Inject a fake --format field at the beginning of the
 	 * arguments, with the format inferred from our output
@@ -53,18 +56,20 @@ static int run_remote_archiver(int argc, const char **argv,
 		packet_write_fmt(fd[1], "argument %s\n", argv[i]);
 	packet_flush(fd[1]);
 
-	buf = packet_read_line(fd[0], NULL);
-	if (!buf)
+	status = packet_reader_read(&reader);
+
+	if (status != PACKET_READ_NORMAL || reader.pktlen <= 0)
 		die(_("git archive: expected ACK/NAK, got a flush packet"));
-	if (strcmp(buf, "ACK")) {
-		if (starts_with(buf, "NACK "))
-			die(_("git archive: NACK %s"), buf + 5);
-		if (starts_with(buf, "ERR "))
-			die(_("remote error: %s"), buf + 4);
+	if (strcmp(reader.line, "ACK")) {
+		if (starts_with(reader.line, "NACK "))
+			die(_("git archive: NACK %s"), reader.line + 5);
+		if (starts_with(reader.line, "ERR "))
+			die(_("remote error: %s"), reader.line + 4);
 		die(_("git archive: protocol error"));
 	}
 
-	if (packet_read_line(fd[0], NULL))
+	status = packet_reader_read(&reader);
+	if (status == PACKET_READ_NORMAL && reader.pktlen > 0)
 		die(_("git archive: expected a flush"));
 
 	/* Now, start reading from fd[0] and spit it out to stdout */
-- 
2.19.0.605.g01d371f741-goog

Re: [PATCH v2 2/4] archive: use packet_reader for communications

[Stefan Beller]

On Wed, Sep 26, 2018 at 6:25 PM Josh Steadmon <steadmon@google.com> wrote:
>
> Using packet_reader will simplify version detection and capability
> handling, which will make implementation of protocol v2 support in
> git-archive easier.
>
> This refactoring does not change the behavior of "git archive".
>
> Signed-off-by: Josh Steadmon <steadmon@google.com>

This patch is
Reviewed-by: Stefan Beller <sbeller@google.com>

Thanks!

> ---
>  builtin/archive.c | 23 ++++++++++++++---------
>  1 file changed, 14 insertions(+), 9 deletions(-)
>
> diff --git a/builtin/archive.c b/builtin/archive.c
> index e74f675390..4eb547c5b7 100644
> --- a/builtin/archive.c
> +++ b/builtin/archive.c
> @@ -27,10 +27,11 @@ static int run_remote_archiver(int argc, const char **argv,
>                                const char *remote, const char *exec,
>                                const char *name_hint)
>  {
> -       char *buf;
>         int fd[2], i, rv;
>         struct transport *transport;
>         struct remote *_remote;
> +       struct packet_reader reader;
> +       enum packet_read_status status;
>
>         _remote = remote_get(remote);
>         if (!_remote->url[0])
> @@ -38,6 +39,8 @@ static int run_remote_archiver(int argc, const char **argv,
>         transport = transport_get(_remote, _remote->url[0]);
>         transport_connect(transport, "git-upload-archive", exec, fd);
>
> +       packet_reader_init(&reader, fd[0], NULL, 0, PACKET_READ_CHOMP_NEWLINE);
> +
>         /*
>          * Inject a fake --format field at the beginning of the
>          * arguments, with the format inferred from our output
> @@ -53,18 +56,20 @@ static int run_remote_archiver(int argc, const char **argv,
>                 packet_write_fmt(fd[1], "argument %s\n", argv[i]);
>         packet_flush(fd[1]);
>
> -       buf = packet_read_line(fd[0], NULL);
> -       if (!buf)
> +       status = packet_reader_read(&reader);
> +
> +       if (status != PACKET_READ_NORMAL || reader.pktlen <= 0)
>                 die(_("git archive: expected ACK/NAK, got a flush packet"));
> -       if (strcmp(buf, "ACK")) {
> -               if (starts_with(buf, "NACK "))
> -                       die(_("git archive: NACK %s"), buf + 5);
> -               if (starts_with(buf, "ERR "))
> -                       die(_("remote error: %s"), buf + 4);
> +       if (strcmp(reader.line, "ACK")) {
> +               if (starts_with(reader.line, "NACK "))
> +                       die(_("git archive: NACK %s"), reader.line + 5);
> +               if (starts_with(reader.line, "ERR "))
> +                       die(_("remote error: %s"), reader.line + 4);
>                 die(_("git archive: protocol error"));
>         }
>
> -       if (packet_read_line(fd[0], NULL))
> +       status = packet_reader_read(&reader);
> +       if (status == PACKET_READ_NORMAL && reader.pktlen > 0)
>                 die(_("git archive: expected a flush"));
>
>         /* Now, start reading from fd[0] and spit it out to stdout */
> --
> 2.19.0.605.g01d371f741-goog
>

[PATCH v2 3/4] archive: implement protocol v2 archive command

[Josh Steadmon]

This adds a new archive command for protocol v2. The command expects
arguments in the form "argument X" which are passed unmodified to
git-upload-archive--writer.

This command works over the file://, Git, and SSH transports. HTTP
support will be added in a separate patch.

NEEDSWORK: this is not backwards-compatible with older clients that set
GIT_PROTOCOL=version=2 or configure protocol.version=2.

Signed-off-by: Josh Steadmon <steadmon@google.com>
---
 Documentation/technical/protocol-v2.txt | 21 +++++++++++-
 builtin/archive.c                       | 45 +++++++++++++++++--------
 builtin/upload-archive.c                | 27 +++++++++++++--
 serve.c                                 |  7 ++++
 t/t5000-tar-tree.sh                     |  7 ++++
 t/t5701-git-serve.sh                    |  1 +
 6 files changed, 90 insertions(+), 18 deletions(-)

diff --git a/Documentation/technical/protocol-v2.txt b/Documentation/technical/protocol-v2.txt
index 09e4e0273f..6126fc5738 100644
--- a/Documentation/technical/protocol-v2.txt
+++ b/Documentation/technical/protocol-v2.txt
@@ -77,7 +77,8 @@ A v2 server would reply:
    S: <capability-advertisement>
 
 Subsequent requests are then made directly to the service
-`$GIT_URL/git-upload-pack`. (This works the same for git-receive-pack).
+`$GIT_URL/git-upload-pack`. (This works the same for git-receive-pack or
+git-upload-archive).
 
  Capability Advertisement
 --------------------------
@@ -168,6 +169,24 @@ printable ASCII characters except space (i.e., the byte range 32 < x <
 and debugging purposes, and MUST NOT be used to programmatically assume
 the presence or absence of particular features.
 
+ archive
+~~~~~~~~~
+
+`archive` is the command to request an archive (such as a tarball) from a server
+over v2.
+
+archive takes the following optional arguments:
+
+    argument <arg>
+       This specifies that <arg> should be passed as an argument to the
+       underlying archive writer.  This option can be repeated to pass
+       additional arguments to the archive writer.
+
+See linkgit:git-archive[1] for allowed values of `<arg>`.
+
+The output of archive is a packet-line stream of the resulting archive, with
+error messages transferred over the sideband channel.
+
  ls-refs
 ~~~~~~~~~
 
diff --git a/builtin/archive.c b/builtin/archive.c
index 4eb547c5b7..f91d222677 100644
--- a/builtin/archive.c
+++ b/builtin/archive.c
@@ -5,9 +5,11 @@
 #include "cache.h"
 #include "builtin.h"
 #include "archive.h"
+#include "connect.h"
 #include "transport.h"
 #include "parse-options.h"
 #include "pkt-line.h"
+#include "protocol.h"
 #include "sideband.h"
 
 static void create_output_file(const char *output_file)
@@ -23,6 +25,13 @@ static void create_output_file(const char *output_file)
 	}
 }
 
+static void do_v2_command_and_cap(int out)
+{
+	packet_write_fmt(out, "command=archive\n");
+	/* Capability list would go here, if we wanted to request any. */
+	packet_delim(out);
+}
+
 static int run_remote_archiver(int argc, const char **argv,
 			       const char *remote, const char *exec,
 			       const char *name_hint)
@@ -32,6 +41,7 @@ static int run_remote_archiver(int argc, const char **argv,
 	struct remote *_remote;
 	struct packet_reader reader;
 	enum packet_read_status status;
+	enum protocol_version version;
 
 	_remote = remote_get(remote);
 	if (!_remote->url[0])
@@ -41,6 +51,11 @@ static int run_remote_archiver(int argc, const char **argv,
 
 	packet_reader_init(&reader, fd[0], NULL, 0, PACKET_READ_CHOMP_NEWLINE);
 
+	version = discover_version(&reader);
+
+	if (version == protocol_v2 && server_supports_v2("archive", 0))
+		do_v2_command_and_cap(fd[1]);
+
 	/*
 	 * Inject a fake --format field at the beginning of the
 	 * arguments, with the format inferred from our output
@@ -56,22 +71,24 @@ static int run_remote_archiver(int argc, const char **argv,
 		packet_write_fmt(fd[1], "argument %s\n", argv[i]);
 	packet_flush(fd[1]);
 
-	status = packet_reader_read(&reader);
-
-	if (status != PACKET_READ_NORMAL || reader.pktlen <= 0)
-		die(_("git archive: expected ACK/NAK, got a flush packet"));
-	if (strcmp(reader.line, "ACK")) {
-		if (starts_with(reader.line, "NACK "))
-			die(_("git archive: NACK %s"), reader.line + 5);
-		if (starts_with(reader.line, "ERR "))
-			die(_("remote error: %s"), reader.line + 4);
-		die(_("git archive: protocol error"));
+	if (version == protocol_v0) {
+		status = packet_reader_read(&reader);
+
+		if (status != PACKET_READ_NORMAL || reader.pktlen <= 0)
+			die(_("git archive: expected ACK/NAK, got a flush packet"));
+		if (strcmp(reader.line, "ACK")) {
+			if (starts_with(reader.line, "NACK "))
+				die(_("git archive: NACK %s"), reader.line + 5);
+			if (starts_with(reader.line, "ERR "))
+				die(_("remote error: %s"), reader.line + 4);
+			die(_("git archive: protocol error"));
+		}
+
+		status = packet_reader_read(&reader);
+		if (status == PACKET_READ_NORMAL && reader.pktlen > 0)
+			die(_("git archive: expected a flush"));
 	}
 
-	status = packet_reader_read(&reader);
-	if (status == PACKET_READ_NORMAL && reader.pktlen > 0)
-		die(_("git archive: expected a flush"));
-
 	/* Now, start reading from fd[0] and spit it out to stdout */
 	rv = recv_sideband("archive", fd[0], 1);
 	rv |= transport_disconnect(transport);
diff --git a/builtin/upload-archive.c b/builtin/upload-archive.c
index 25d9116356..b8a8fb256f 100644
--- a/builtin/upload-archive.c
+++ b/builtin/upload-archive.c
@@ -5,6 +5,8 @@
 #include "builtin.h"
 #include "archive.h"
 #include "pkt-line.h"
+#include "protocol.h"
+#include "serve.h"
 #include "sideband.h"
 #include "run-command.h"
 #include "argv-array.h"
@@ -76,10 +78,24 @@ static ssize_t process_input(int child_fd, int band)
 int cmd_upload_archive(int argc, const char **argv, const char *prefix)
 {
 	struct child_process writer = { argv };
+	enum protocol_version version = determine_protocol_version_server();
 
 	if (argc == 2 && !strcmp(argv[1], "-h"))
 		usage(upload_archive_usage);
 
+	if (version == protocol_v2) {
+		struct serve_options options = SERVE_OPTIONS_INIT;
+
+		/* Send "version 2" message and capabilities. */
+		options.advertise_capabilities = 1;
+		serve(&options);
+
+		/* Process command request and validate client capabilities. */
+		options.advertise_capabilities = 0;
+		options.stateless_rpc = 1;
+		serve(&options);
+	}
+
 	/*
 	 * Set up sideband subprocess.
 	 *
@@ -92,12 +108,17 @@ int cmd_upload_archive(int argc, const char **argv, const char *prefix)
 	writer.git_cmd = 1;
 	if (start_command(&writer)) {
 		int err = errno;
-		packet_write_fmt(1, "NACK unable to spawn subprocess\n");
+		if (version == protocol_v0 || version == protocol_v1)
+			packet_write_fmt(1, "NACK unable to spawn subprocess\n");
+		else if (version == protocol_v2)
+			error_clnt("unable to spawn subprocess\n");
 		die("upload-archive: %s", strerror(err));
 	}
 
-	packet_write_fmt(1, "ACK\n");
-	packet_flush(1);
+	if (version == protocol_v0 || version == protocol_v1) {
+		packet_write_fmt(1, "ACK\n");
+		packet_flush(1);
+	}
 
 	while (1) {
 		struct pollfd pfd[2];
diff --git a/serve.c b/serve.c
index bda085f09c..cef575086f 100644
--- a/serve.c
+++ b/serve.c
@@ -52,8 +52,15 @@ struct protocol_capability {
 		       struct packet_reader *request);
 };
 
+static int noop(struct repository *r, struct argv_array *keys,
+		struct packet_reader *request)
+{
+	return 0;
+}
+
 static struct protocol_capability capabilities[] = {
 	{ "agent", agent_advertise, NULL },
+	{ "archive", always_advertise, noop },
 	{ "ls-refs", always_advertise, ls_refs },
 	{ "fetch", upload_pack_advertise, upload_pack_v2 },
 	{ "server-option", always_advertise, NULL },
diff --git a/t/t5000-tar-tree.sh b/t/t5000-tar-tree.sh
index c408e3a23d..4a76354021 100755
--- a/t/t5000-tar-tree.sh
+++ b/t/t5000-tar-tree.sh
@@ -138,6 +138,13 @@ test_expect_success \
 
 test_expect_success 'extract archive' 'check_tar b'
 
+test_expect_success 'protocol v2 for remote' '
+	GIT_PROTOCOL="version=2" GIT_TRACE_PACKET="$(pwd)/log" git archive \
+		--remote=. HEAD >v2_remote.tar &&
+	grep "version 2" log
+'
+test_expect_success 'extract v2 archive' 'check_tar v2_remote'
+
 test_expect_success 'git archive --prefix=prefix/' '
 	git archive --prefix=prefix/ HEAD >with_prefix.tar
 '
diff --git a/t/t5701-git-serve.sh b/t/t5701-git-serve.sh
index 75ec79e6cb..f47a14660b 100755
--- a/t/t5701-git-serve.sh
+++ b/t/t5701-git-serve.sh
@@ -8,6 +8,7 @@ test_expect_success 'test capability advertisement' '
 	cat >expect <<-EOF &&
 	version 2
 	agent=git/$(git version | cut -d" " -f3)
+	archive
 	ls-refs
 	fetch=shallow
 	server-option
-- 
2.19.0.605.g01d371f741-goog

[PATCH v2 4/4] archive: allow archive over HTTP(S) with proto v2

[Josh Steadmon]

Signed-off-by: Josh Steadmon <steadmon@google.com>
---
 builtin/archive.c  | 12 +++++++++++-
 http-backend.c     | 13 ++++++++++++-
 transport-helper.c |  7 ++++---
 3 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/builtin/archive.c b/builtin/archive.c
index f91d222677..78a259518d 100644
--- a/builtin/archive.c
+++ b/builtin/archive.c
@@ -87,7 +87,17 @@ static int run_remote_archiver(int argc, const char **argv,
 		status = packet_reader_read(&reader);
 		if (status == PACKET_READ_NORMAL && reader.pktlen > 0)
 			die(_("git archive: expected a flush"));
-	}
+	} else if (version == protocol_v2 &&
+		   (starts_with(transport->url, "http://") ||
+		    starts_with(transport->url, "https://")))
+		/*
+		 * Commands over HTTP require two requests, so there's an
+		 * additional server response to parse. We do only basic sanity
+		 * checking here that the versions presented match across
+		 * requests.
+		 */
+		if (version != discover_version(&reader))
+			die(_("git archive: received different protocol versions in subsequent requests"));
 
 	/* Now, start reading from fd[0] and spit it out to stdout */
 	rv = recv_sideband("archive", fd[0], 1);
diff --git a/http-backend.c b/http-backend.c
index 9e894f197f..8e262d50e0 100644
--- a/http-backend.c
+++ b/http-backend.c
@@ -32,6 +32,7 @@ struct rpc_service {
 static struct rpc_service rpc_service[] = {
 	{ "upload-pack", "uploadpack", 1, 1 },
 	{ "receive-pack", "receivepack", 0, -1 },
+	{ "upload-archive", "uploadarchive", 1, 1 },
 };
 
 static struct string_list *get_parameters(void)
@@ -637,6 +638,15 @@ static void service_rpc(struct strbuf *hdr, char *service_name)
 	struct rpc_service *svc = select_service(hdr, service_name);
 	struct strbuf buf = STRBUF_INIT;
 
+	if (!strcmp(service_name, "git-upload-archive")) {
+		/*
+		 * git-upload-archive doesn't need --stateless-rpc, because it
+		 * always handles only a single request.
+		 */
+		argv[1] = ".";
+		argv[2] = NULL;
+	}
+
 	strbuf_reset(&buf);
 	strbuf_addf(&buf, "application/x-git-%s-request", svc->name);
 	check_content_type(hdr, buf.buf);
@@ -713,7 +723,8 @@ static struct service_cmd {
 	{"GET", "/objects/pack/pack-[0-9a-f]{40}\\.idx$", get_idx_file},
 
 	{"POST", "/git-upload-pack$", service_rpc},
-	{"POST", "/git-receive-pack$", service_rpc}
+	{"POST", "/git-receive-pack$", service_rpc},
+	{"POST", "/git-upload-archive$", service_rpc},
 };
 
 static int bad_request(struct strbuf *hdr, const struct service_cmd *c)
diff --git a/transport-helper.c b/transport-helper.c
index 143ca008c8..c41c3dfcff 100644
--- a/transport-helper.c
+++ b/transport-helper.c
@@ -604,8 +604,9 @@ static int process_connect_service(struct transport *transport,
 		strbuf_addf(&cmdbuf, "connect %s\n", name);
 		ret = run_connect(transport, &cmdbuf);
 	} else if (data->stateless_connect &&
-		   (get_protocol_version_config() == protocol_v2) &&
-		   !strcmp("git-upload-pack", name)) {
+		   get_protocol_version_config() == protocol_v2 &&
+		   (!strcmp("git-upload-pack", name) ||
+		    !strcmp("git-upload-archive", name))) {
 		strbuf_addf(&cmdbuf, "stateless-connect %s\n", name);
 		ret = run_connect(transport, &cmdbuf);
 		if (ret)
@@ -639,7 +640,7 @@ static int connect_helper(struct transport *transport, const char *name,
 
 	/* Get_helper so connect is inited. */
 	get_helper(transport);
-	if (!data->connect)
+	if (!data->connect && !data->stateless_connect)
 		die(_("operation not supported by protocol"));
 
 	if (!process_connect_service(transport, name, exec))
-- 
2.19.0.605.g01d371f741-goog

Re: [PATCH v2 0/4] Add proto v2 archive command with HTTP support

[Stefan Beller]

On Wed, Sep 26, 2018 at 6:25 PM Josh Steadmon <steadmon@google.com> wrote:
>
> This is the second version of my series to add a new protocol v2 command
> for archiving, with support for HTTP(S).
>
> NEEDSWORK: a server built with this series is not backwards-compatible
> with clients that set GIT_PROTOCOL=version=2 or configure
> protocol.version=2. The old client will unconditionally send "argument
> ..." packet lines, which breaks the server's expectations of a
> "command=archive" request,

So if an old client sets protocol to v2, it would only apply that
protocol version
to fetch, not archive, so it would start following a v0 conversation, but
as the protocol version is set, it would be transmitted to the server.
This sounds like a bug in the client?

>  while the server's capability advertisement
> in turn breaks the clients expectation of either an ACK or NACK.

Could a modern client send either another protocol version (3?)
or a special capability along the protocol version ("fixed_archive")

> I've been discussing workarounds for this with Jonathan Nieder, but
> please let me know if you have any suggestions for v3 of this series.

Care to open the discussion to the list? What are the different
approaches, what are the pros/cons?

Re: [PATCH v2 0/4] Add proto v2 archive command with HTTP support

[Jonathan Nieder]

Stefan Beller wrote:
> On Wed, Sep 26, 2018 at 6:25 PM Josh Steadmon <steadmon@google.com> wrote:

>> I've been discussing workarounds for this with Jonathan Nieder, but
>> please let me know if you have any suggestions for v3 of this series.
>
> Care to open the discussion to the list? What are the different
> approaches, what are the pros/cons?

Do you mean sending video of chatting in the office?

Josh and I discussed that

 1. Clients sending version=2 when they do not, in fact, speak protocol
    v2 for a service is a (serious) bug.  (Separately from this
    series) we should fix it.

 2. That bug is already in the wild, alas.  Fortunately the semantics of
    GIT_PROTOCOL as a list of key/value pairs is well defined.  So we
    have choices of (a) bump version to version=3 (b) pass another
    value 'version=2:yesreallyversion=2' (c) etc.

 3. This is likely to affect push, too.

Thanks and hope that helps,
Jonathan

Re: [PATCH v2 0/4] Add proto v2 archive command with HTTP support

[Junio C Hamano]

Jonathan Nieder <jrnieder@gmail.com> writes:

>  1. Clients sending version=2 when they do not, in fact, speak protocol
>     v2 for a service is a (serious) bug.  (Separately from this
>     series) we should fix it.
>
>  2. That bug is already in the wild, alas.  Fortunately the semantics of
>     GIT_PROTOCOL as a list of key/value pairs is well defined.  So we
>     have choices of (a) bump version to version=3 (b) pass another
>     value 'version=2:yesreallyversion=2' (c) etc.
>
>  3. This is likely to affect push, too.

Do you mean that existing "git push", "git fetch" and "git archive"
sends version=2 even when they are not capable of speaking protocol
v2?  I thought that "git archive [--remote]" was left outside of the
protocol update (that was the reason why the earlier attempt took a
hacky route of "shallow clone followed by local archive"), so there
is no "git archive" in the wild that can even say "version=$n"
(which requires you to be at least version=1)?

Re: [PATCH v2 0/4] Add proto v2 archive command with HTTP support

[Josh Steadmon]

On 2018.09.27 15:20, Junio C Hamano wrote:
> Jonathan Nieder <jrnieder@gmail.com> writes:
> 
> >  1. Clients sending version=2 when they do not, in fact, speak protocol
> >     v2 for a service is a (serious) bug.  (Separately from this
> >     series) we should fix it.
> >
> >  2. That bug is already in the wild, alas.  Fortunately the semantics of
> >     GIT_PROTOCOL as a list of key/value pairs is well defined.  So we
> >     have choices of (a) bump version to version=3 (b) pass another
> >     value 'version=2:yesreallyversion=2' (c) etc.
> >
> >  3. This is likely to affect push, too.
> 
> Do you mean that existing "git push", "git fetch" and "git archive"
> sends version=2 even when they are not capable of speaking protocol
> v2?  I thought that "git archive [--remote]" was left outside of the
> protocol update (that was the reason why the earlier attempt took a
> hacky route of "shallow clone followed by local archive"), so there
> is no "git archive" in the wild that can even say "version=$n"
> (which requires you to be at least version=1)?

Yes, the version on my desktop sends version=2 when archiving:

∫ which git
/usr/bin/git
∫ git --version
git version 2.19.0.605.g01d371f741-goog
∫ GIT_TRACE_PACKET=${HOME}/server_trace git daemon \
  --enable=upload-archive \
  --base-path=${HOME}/src/bare-repos &
[1] 258496
∫ git archive --remote git://localhost/test-repo.git HEAD >! test.tar
∫ grep version ~/server_trace
15:31:22.377869 pkt-line.c:80           packet:          git< git-upload-archive /test-repo.git\0host=localhost\0\0version=2\0

Re: [PATCH v2 0/4] Add proto v2 archive command with HTTP support

[Junio C Hamano]

Josh Steadmon <steadmon@google.com> writes:

> Yes, the version on my desktop sends version=2 when archiving:
>
> ∫ which git
> /usr/bin/git
> ∫ git --version
> git version 2.19.0.605.g01d371f741-goog
> ∫ GIT_TRACE_PACKET=${HOME}/server_trace git daemon \
>   --enable=upload-archive \
>   --base-path=${HOME}/src/bare-repos &
> [1] 258496
> ∫ git archive --remote git://localhost/test-repo.git HEAD >! test.tar
> ∫ grep version ~/server_trace
> 15:31:22.377869 pkt-line.c:80           packet:          git< git-upload-archive /test-repo.git\0host=localhost\0\0version=2\0

Ah, that's truly broken.

Come to think of it, do we need to be using uniform versions across
different endpoints?  The archive request could be at v3 while fetch
request could still be at v2, in which case the design to use a
single protocol.version variable is probably the root cause of the
confusion?  Perhaps like protocol.<name>.allow, we would want
protocol.<name>.version or something like that (and no
protocol.version) to make it clear that protocol v2 used for
fetching has nothing to do with protocol v1 or v2 or v3 used for
archiving?

Luckily, protocol.version is still marked as experimental so it is
not too bad that we caught the design mistake (if it is one) and can
now correct it before the damage spreads too widely.

Re: [PATCH v2 0/4] Add proto v2 archive command with HTTP support

[Josh Steadmon]

On 2018.09.27 11:20, Stefan Beller wrote:
> On Wed, Sep 26, 2018 at 6:25 PM Josh Steadmon <steadmon@google.com> wrote:
> >
> > This is the second version of my series to add a new protocol v2 command
> > for archiving, with support for HTTP(S).
> >
> > NEEDSWORK: a server built with this series is not backwards-compatible
> > with clients that set GIT_PROTOCOL=version=2 or configure
> > protocol.version=2. The old client will unconditionally send "argument
> > ..." packet lines, which breaks the server's expectations of a
> > "command=archive" request,
> 
> So if an old client sets protocol to v2, it would only apply that
> protocol version
> to fetch, not archive, so it would start following a v0 conversation, but
> as the protocol version is set, it would be transmitted to the server.
> This sounds like a bug in the client?

Yeah, basically. We're telling the server we support v2, even if the
specific operation we're trying to do doesn't have a v2 implementation
on the client. So this is going to make it ugly to replace existing
commands.

> >  while the server's capability advertisement
> > in turn breaks the clients expectation of either an ACK or NACK.
> 
> Could a modern client send either another protocol version (3?)
> or a special capability along the protocol version ("fixed_archive")
> 
> > I've been discussing workarounds for this with Jonathan Nieder, but
> > please let me know if you have any suggestions for v3 of this series.
> 
> Care to open the discussion to the list? What are the different
> approaches, what are the pros/cons?

Jonathan suggested something along the lines of what you said above,
adding a new field in GIT_PROTOCOL. So we'd send something like
"version=2:archive_version=2" and have the server detect the latter.

I'm not sure if that's the best way to go about this since I'm not
familiar with the version detection code for other parts of the system.
I worry that it will lead us down the path of having to specify a
version for every command that we eventually convert to protocol v2. On
the other hand, I don't see any other way to work around this, at least
in the archive case. We can't peek at the client's transmissions on the
server, because v2 requires that the server speaks first...