[PATCH 0/2] minor show-index modernizations

[PATCH 0/2] minor show-index modernizations

[Jeff King]

While recommending show-index to somebody today, I noticed that it has a
few ancient warts. This series turns it into a builtin and fixes the
documentation. I suspect it could do with some more modernization and
friendliness, like:

  - re-using the existing packfile.c code instead of re-implementing
    index-reading (though the packfile code would definitely need some
    refactoring to make this work)

  - it could probably handle arguments as files instead of requiring
    stdin redirection

I'll leave those for now, as they're not worth the effort to me at this
point. But everybody who _doesn't_ use the command benefits from making
it a builtin, so it seems like an easy win.

  [1/2]: make show-index a builtin
  [2/2]: show-index: update documentation for index v2

 Documentation/git-show-index.txt     | 22 ++++++++++++++++------
 Makefile                             |  2 +-
 builtin.h                            |  1 +
 show-index.c => builtin/show-index.c |  2 +-
 git.c                                |  1 +
 5 files changed, 20 insertions(+), 8 deletions(-)
 rename show-index.c => builtin/show-index.c (96%)

-Peff

[PATCH 1/2] make show-index a builtin

[Jeff King]

The git-show-index command is built as its own separate
program. There's really no good reason for this, and it
means we waste extra space on disk (and CPU time running the
linker). Let's fold it in to the main binary as a builtin.

The history here is actually a bit amusing. The program
itself is mostly self-contained, and doesn't even use our
normal pack index code. In a5031214c4 (slim down "git
show-index", 2010-01-21), we even stopped using xmalloc() so
that it could avoid libgit.a entirely. But then 040a655116
(cleanup: use internal memory allocation wrapper functions
everywhere, 2011-10-06) switched that back to xmalloc, which
later become ALLOC_ARRAY().

Making it a builtin should give us the best of both worlds:
no wasted space and no need to avoid the usual patterns.

Signed-off-by: Jeff King <peff@peff.net>
---
 Makefile                             | 2 +-
 builtin.h                            | 1 +
 show-index.c => builtin/show-index.c | 2 +-
 git.c                                | 1 +
 4 files changed, 4 insertions(+), 2 deletions(-)
 rename show-index.c => builtin/show-index.c (96%)

diff --git a/Makefile b/Makefile
index ad880d1fc5..766c5909bf 100644
--- a/Makefile
+++ b/Makefile
@@ -689,7 +689,6 @@ PROGRAM_OBJS += http-backend.o
 PROGRAM_OBJS += imap-send.o
 PROGRAM_OBJS += sh-i18n--envsubst.o
 PROGRAM_OBJS += shell.o
-PROGRAM_OBJS += show-index.o
 PROGRAM_OBJS += remote-testsvn.o
 
 # Binary suffix, set to .exe for Windows builds
@@ -1076,6 +1075,7 @@ BUILTIN_OBJS += builtin/send-pack.o
 BUILTIN_OBJS += builtin/serve.o
 BUILTIN_OBJS += builtin/shortlog.o
 BUILTIN_OBJS += builtin/show-branch.o
+BUILTIN_OBJS += builtin/show-index.o
 BUILTIN_OBJS += builtin/show-ref.o
 BUILTIN_OBJS += builtin/stripspace.o
 BUILTIN_OBJS += builtin/submodule--helper.o
diff --git a/builtin.h b/builtin.h
index 4e0f64723e..0362f1ce25 100644
--- a/builtin.h
+++ b/builtin.h
@@ -220,6 +220,7 @@ extern int cmd_serve(int argc, const char **argv, const char *prefix);
 extern int cmd_shortlog(int argc, const char **argv, const char *prefix);
 extern int cmd_show(int argc, const char **argv, const char *prefix);
 extern int cmd_show_branch(int argc, const char **argv, const char *prefix);
+extern int cmd_show_index(int argc, const char **argv, const char *prefix);
 extern int cmd_status(int argc, const char **argv, const char *prefix);
 extern int cmd_stripspace(int argc, const char **argv, const char *prefix);
 extern int cmd_submodule__helper(int argc, const char **argv, const char *prefix);
diff --git a/show-index.c b/builtin/show-index.c
similarity index 96%
rename from show-index.c
rename to builtin/show-index.c
index 1ead41e211..65fa86dd08 100644
--- a/show-index.c
+++ b/builtin/show-index.c
@@ -4,7 +4,7 @@
 static const char show_index_usage[] =
 "git show-index";
 
-int cmd_main(int argc, const char **argv)
+int cmd_show_index(int argc, const char **argv, const char *prefix)
 {
 	int i;
 	unsigned nr;
diff --git a/git.c b/git.c
index 5771d62a32..c91e144d9a 100644
--- a/git.c
+++ b/git.c
@@ -470,6 +470,7 @@ static struct cmd_struct commands[] = {
 	{ "shortlog", cmd_shortlog, RUN_SETUP_GENTLY | USE_PAGER },
 	{ "show", cmd_show, RUN_SETUP },
 	{ "show-branch", cmd_show_branch, RUN_SETUP },
+	{ "show-index", cmd_show_index },
 	{ "show-ref", cmd_show_ref, RUN_SETUP },
 	{ "stage", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 	{ "status", cmd_status, RUN_SETUP | NEED_WORK_TREE },
-- 
2.17.0.1391.g6fdbf40724

[PATCH 2/2] show-index: update documentation for index v2

[Jeff King]

Commit 32637cdf4a (show-index.c: learn about index v2,
2007-04-09) changed the output format of show-index to
include the object CRC32 but didn't update the
documentation. Let's fix that and generally describe the
output in more detail.

There are a few other fixes here while we're rewording:

 - refer to index-pack along with pack-objects, since either
   can create .idx files

 - use "linkgit:" for referring to other commands

 - expand the bit about verify-pack, giving reasons why you
   might want this command instead. I almost omitted this
   entirely, but referring to verify-pack might help a
   reader who is looking for more information.

Signed-off-by: Jeff King <peff@peff.net>
---
 Documentation/git-show-index.txt | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/Documentation/git-show-index.txt b/Documentation/git-show-index.txt
index a8a9509e0e..424e4ba84c 100644
--- a/Documentation/git-show-index.txt
+++ b/Documentation/git-show-index.txt
@@ -14,13 +14,27 @@ SYNOPSIS
 
 DESCRIPTION
 -----------
-Read the idx file for a Git packfile created with
-'git pack-objects' command from the standard input, and
-dump its contents.
+Read the `.idx` file for a Git packfile (created with
+linkgit:git-pack-objects[1] or linkgit:git-index-pack[1]) from the
+standard input, and dump its contents. The output consists of one object
+per line, with each line containing two or three space-separated
+columns:
 
-The information it outputs is subset of what you can get from
-'git verify-pack -v'; this command only shows the packfile
-offset and SHA-1 of each object.
+  - the first column is the offset in bytes of the object within the
+    corresponding packfile
+
+  - the second column is the object id of the object
+
+  - if the index version is 2 or higher, the third column contains the
+    CRC32 of the object data
+
+The objects are output in the order in which they are found in the index
+file, which should be (in a correctly constructed file) sorted by object
+id.
+
+Note that you can get more information on a packfile by calling
+linkgit:git-verify-pack[1]. However, as this command considers only the
+index file itself, it's both faster and more flexible.
 
 GIT
 ---
-- 
2.17.0.1391.g6fdbf40724

Re: [PATCH 1/2] make show-index a builtin

[Junio C Hamano]

Jeff King <peff@peff.net> writes:

> diff --git a/show-index.c b/builtin/show-index.c
> similarity index 96%
> rename from show-index.c
> rename to builtin/show-index.c
> index 1ead41e211..65fa86dd08 100644
> --- a/show-index.c
> +++ b/builtin/show-index.c
> @@ -4,7 +4,7 @@

I squashed

#include "builtin.h"

near the beginning of this file to squelch -DDEVELOPER extra
warnings.  Otherwise looks obviously good.

>  static const char show_index_usage[] =
>  "git show-index";
>  
> -int cmd_main(int argc, const char **argv)
> +int cmd_show_index(int argc, const char **argv, const char *prefix)
>  {
>  	int i;
>  	unsigned nr;
> diff --git a/git.c b/git.c
> index 5771d62a32..c91e144d9a 100644
> --- a/git.c
> +++ b/git.c
> @@ -470,6 +470,7 @@ static struct cmd_struct commands[] = {
>  	{ "shortlog", cmd_shortlog, RUN_SETUP_GENTLY | USE_PAGER },
>  	{ "show", cmd_show, RUN_SETUP },
>  	{ "show-branch", cmd_show_branch, RUN_SETUP },
> +	{ "show-index", cmd_show_index },

Hmph, this does not need SETUP?  Ah, of course, because its
subcommand body used to do everything itself, and this patch just
turns cmd_main() to cmd_show_index().



>  	{ "show-ref", cmd_show_ref, RUN_SETUP },
>  	{ "stage", cmd_add, RUN_SETUP | NEED_WORK_TREE },
>  	{ "status", cmd_status, RUN_SETUP | NEED_WORK_TREE },

Re: [PATCH 1/2] make show-index a builtin

[Jeff King]

On Tue, May 29, 2018 at 12:31:53AM +0900, Junio C Hamano wrote:

> Jeff King <peff@peff.net> writes:
> 
> > diff --git a/show-index.c b/builtin/show-index.c
> > similarity index 96%
> > rename from show-index.c
> > rename to builtin/show-index.c
> > index 1ead41e211..65fa86dd08 100644
> > --- a/show-index.c
> > +++ b/builtin/show-index.c
> > @@ -4,7 +4,7 @@
> 
> I squashed
> 
> #include "builtin.h"
> 
> near the beginning of this file to squelch -DDEVELOPER extra
> warnings.  Otherwise looks obviously good.

Thanks. I'm still using my custom build options, and obviously I need to
add -Wmissing-prototypes.

> > diff --git a/git.c b/git.c
> > index 5771d62a32..c91e144d9a 100644
> > --- a/git.c
> > +++ b/git.c
> > @@ -470,6 +470,7 @@ static struct cmd_struct commands[] = {
> >  	{ "shortlog", cmd_shortlog, RUN_SETUP_GENTLY | USE_PAGER },
> >  	{ "show", cmd_show, RUN_SETUP },
> >  	{ "show-branch", cmd_show_branch, RUN_SETUP },
> > +	{ "show-index", cmd_show_index },
> 
> Hmph, this does not need SETUP?  Ah, of course, because its
> subcommand body used to do everything itself, and this patch just
> turns cmd_main() to cmd_show_index().

It is not even that it does the setup itself. It does not need the setup
at all, because it is purely a mechanical parsing of the stdin stream
to text output. No repo required, and it does not know or care if the
matching packfile even exists.

-Peff