[PATCH 00/17] object_id part 14

[PATCH 00/17] object_id part 14

[brian m. carlson]

This is the fourteenth series of patches to switch to using struct
object_id and the_hash_algo.  This series converts several core pieces
to use struct object_id, including the oid* and hex functions.

All of these patches have been tested with both SHA-1 and a 256-bit
hash.

brian m. carlson (17):
  cache: update object ID functions for the_hash_algo
  tree-walk: replace hard-coded constants with the_hash_algo
  hex: switch to using the_hash_algo
  commit: express tree entry constants in terms of the_hash_algo
  strbuf: allocate space with GIT_MAX_HEXSZ
  sha1-name: use the_hash_algo when parsing object names
  commit: increase commit message buffer size
  refs/files-backend: use the_hash_algo for writing refs
  builtin/update-index: convert to using the_hash_algo
  builtin/update-index: simplify parsing of cacheinfo
  builtin/fmt-merge-msg: make hash independent
  builtin/merge: switch to use the_hash_algo
  builtin/merge-recursive: make hash independent
  diff: switch GIT_SHA1_HEXSZ to use the_hash_algo
  log-tree: switch GIT_SHA1_HEXSZ to the_hash_algo->hexsz
  sha1-file: convert constants to uses of the_hash_algo
  pretty: switch hard-coded constants to the_hash_algo

 builtin/fmt-merge-msg.c   | 19 ++++++++++---------
 builtin/merge-recursive.c |  4 ++--
 builtin/merge.c           | 11 ++++++-----
 builtin/update-index.c    | 14 ++++++++------
 cache.h                   |  6 +++---
 commit.c                  |  4 ++--
 diff.c                    |  6 +++---
 hex.c                     |  6 +++---
 log-tree.c                |  2 +-
 pretty.c                  |  4 ++--
 refs/files-backend.c      |  6 +++---
 sha1-file.c               |  8 ++++----
 sha1-name.c               | 12 +++++++-----
 strbuf.c                  |  2 +-
 tree-walk.c               |  3 ++-
 15 files changed, 57 insertions(+), 50 deletions(-)

[PATCH 01/17] cache: update object ID functions for the_hash_algo

[brian m. carlson]

Update the hashcpy and hashclr functions to use the_hash_algo, since
they are used in a variety of places to copy and manipulate buffers that
need to move data into or out of struct object_id.  Update oidcmp so
that it is implemented on its own and similarly uses the_hash_algo.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 cache.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/cache.h b/cache.h
index d49092d94d..c4a64278a1 100644
--- a/cache.h
+++ b/cache.h
@@ -977,7 +977,7 @@ static inline int hashcmp(const unsigned char *sha1, const unsigned char *sha2)
 
 static inline int oidcmp(const struct object_id *oid1, const struct object_id *oid2)
 {
-	return hashcmp(oid1->hash, oid2->hash);
+	return memcmp(oid1->hash, oid2->hash, the_hash_algo->rawsz);
 }
 
 static inline int is_null_sha1(const unsigned char *sha1)
@@ -992,7 +992,7 @@ static inline int is_null_oid(const struct object_id *oid)
 
 static inline void hashcpy(unsigned char *sha_dst, const unsigned char *sha_src)
 {
-	memcpy(sha_dst, sha_src, GIT_SHA1_RAWSZ);
+	memcpy(sha_dst, sha_src, the_hash_algo->rawsz);
 }
 
 static inline void oidcpy(struct object_id *dst, const struct object_id *src)
@@ -1009,7 +1009,7 @@ static inline struct object_id *oiddup(const struct object_id *src)
 
 static inline void hashclr(unsigned char *hash)
 {
-	memset(hash, 0, GIT_SHA1_RAWSZ);
+	memset(hash, 0, the_hash_algo->rawsz);
 }
 
 static inline void oidclr(struct object_id *oid)

Re: [PATCH 01/17] cache: update object ID functions for the_hash_algo

[Jacob Keller]

On Sun, Jul 8, 2018 at 4:39 PM brian m. carlson
<sandals@crustytoothpaste.net> wrote:
>  static inline int oidcmp(const struct object_id *oid1, const struct object_id *oid2)
>  {
> -       return hashcmp(oid1->hash, oid2->hash);
> +       return memcmp(oid1->hash, oid2->hash, the_hash_algo->rawsz);
>  }
>

Just curious, what's the reasoning for not using the hashcmp anymore?

Thanks,
Jake

Re: [PATCH 01/17] cache: update object ID functions for the_hash_algo

[Eric Sunshine]

On Sun, Jul 8, 2018 at 10:38 PM Jacob Keller <jacob.keller@gmail.com> wrote:
> On Sun, Jul 8, 2018 at 4:39 PM brian m. carlson
> <sandals@crustytoothpaste.net> wrote:
> >  static inline int oidcmp(const struct object_id *oid1, const struct object_id *oid2)
> >  {
> > -       return hashcmp(oid1->hash, oid2->hash);
> > +       return memcmp(oid1->hash, oid2->hash, the_hash_algo->rawsz);
> >  }
>
> Just curious, what's the reasoning for not using the hashcmp anymore?

hashcmp() is specific to SHA-1 (for instance, it hardocdes
GIT_SHA1_RAWSZ). oidcmp() is meant as the hash-agnostic replacement
for hashcmp(), so it doesn't make sense to continue implementing
oidcmp() in terms of hashcmp() (the latter of which will eventually be
retired, presumably).

Re: [PATCH 01/17] cache: update object ID functions for the_hash_algo

[Jacob Keller]

On Sun, Jul 8, 2018 at 9:05 PM Eric Sunshine <sunshine@sunshineco.com> wrote:
>
> On Sun, Jul 8, 2018 at 10:38 PM Jacob Keller <jacob.keller@gmail.com> wrote:
> > On Sun, Jul 8, 2018 at 4:39 PM brian m. carlson
> > <sandals@crustytoothpaste.net> wrote:
> > >  static inline int oidcmp(const struct object_id *oid1, const struct object_id *oid2)
> > >  {
> > > -       return hashcmp(oid1->hash, oid2->hash);
> > > +       return memcmp(oid1->hash, oid2->hash, the_hash_algo->rawsz);
> > >  }
> >
> > Just curious, what's the reasoning for not using the hashcmp anymore?
>
> hashcmp() is specific to SHA-1 (for instance, it hardocdes
> GIT_SHA1_RAWSZ). oidcmp() is meant as the hash-agnostic replacement
> for hashcmp(), so it doesn't make sense to continue implementing
> oidcmp() in terms of hashcmp() (the latter of which will eventually be
> retired, presumably).

Fair. I just saw that hashcmp was also updated to use the_hash_algo,
but if we're going to drop it eventually, then there's zero reason to
keep implementing oidcmp in terms of it, so... makes sense to me!

Thanks,
Jake

Re: [PATCH 01/17] cache: update object ID functions for the_hash_algo

[brian m. carlson]

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On Sun, Jul 08, 2018 at 09:31:42PM -0700, Jacob Keller wrote:
> On Sun, Jul 8, 2018 at 9:05 PM Eric Sunshine <sunshine@sunshineco.com> wrote:
> >
> > On Sun, Jul 8, 2018 at 10:38 PM Jacob Keller <jacob.keller@gmail.com> wrote:
> > > On Sun, Jul 8, 2018 at 4:39 PM brian m. carlson
> > > <sandals@crustytoothpaste.net> wrote:
> > > >  static inline int oidcmp(const struct object_id *oid1, const struct object_id *oid2)
> > > >  {
> > > > -       return hashcmp(oid1->hash, oid2->hash);
> > > > +       return memcmp(oid1->hash, oid2->hash, the_hash_algo->rawsz);
> > > >  }
> > >
> > > Just curious, what's the reasoning for not using the hashcmp anymore?
> >
> > hashcmp() is specific to SHA-1 (for instance, it hardocdes
> > GIT_SHA1_RAWSZ). oidcmp() is meant as the hash-agnostic replacement
> > for hashcmp(), so it doesn't make sense to continue implementing
> > oidcmp() in terms of hashcmp() (the latter of which will eventually be
> > retired, presumably).
> 
> Fair. I just saw that hashcmp was also updated to use the_hash_algo,
> but if we're going to drop it eventually, then there's zero reason to
> keep implementing oidcmp in terms of it, so... makes sense to me!

Actually, this reminded me that I have a patch that I had forgotten
about in my next series that updates hashcmp.  I'll squash that in in my
reroll, and undo this change.

As a bonus, it also has a nicer commit message which I will include
explaining why this is necessary.
-- 
brian m. carlson: Houston, Texas, US
OpenPGP: https://keybase.io/bk2204

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[PATCH 02/17] tree-walk: replace hard-coded constants with the_hash_algo

[brian m. carlson]

Remove the hard-coded 20-based values and replace them with uses of
the_hash_algo.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 tree-walk.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tree-walk.c b/tree-walk.c
index 8f5090862b..c1f27086a9 100644
--- a/tree-walk.c
+++ b/tree-walk.c
@@ -26,8 +26,9 @@ static int decode_tree_entry(struct tree_desc *desc, const char *buf, unsigned l
 {
 	const char *path;
 	unsigned int mode, len;
+	const unsigned hashsz = the_hash_algo->rawsz;
 
-	if (size < 23 || buf[size - 21]) {
+	if (size < hashsz + 3 || buf[size - (hashsz + 1)]) {
 		strbuf_addstr(err, _("too-short tree object"));
 		return -1;
 	}

[PATCH 03/17] hex: switch to using the_hash_algo

[brian m. carlson]

Instead of using the GIT_SHA1_* constants, switch to using the_hash_algo
to convert object IDs to and from hex format.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 hex.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/hex.c b/hex.c
index 8df2d63728..10af1a29e8 100644
--- a/hex.c
+++ b/hex.c
@@ -50,7 +50,7 @@ int hex_to_bytes(unsigned char *binary, const char *hex, size_t len)
 int get_sha1_hex(const char *hex, unsigned char *sha1)
 {
 	int i;
-	for (i = 0; i < GIT_SHA1_RAWSZ; i++) {
+	for (i = 0; i < the_hash_algo->rawsz; i++) {
 		int val = hex2chr(hex);
 		if (val < 0)
 			return -1;
@@ -69,7 +69,7 @@ int parse_oid_hex(const char *hex, struct object_id *oid, const char **end)
 {
 	int ret = get_oid_hex(hex, oid);
 	if (!ret)
-		*end = hex + GIT_SHA1_HEXSZ;
+		*end = hex + the_hash_algo->hexsz;
 	return ret;
 }
 
@@ -79,7 +79,7 @@ char *sha1_to_hex_r(char *buffer, const unsigned char *sha1)
 	char *buf = buffer;
 	int i;
 
-	for (i = 0; i < GIT_SHA1_RAWSZ; i++) {
+	for (i = 0; i < the_hash_algo->rawsz; i++) {
 		unsigned int val = *sha1++;
 		*buf++ = hex[val >> 4];
 		*buf++ = hex[val & 0xf];

[PATCH 04/17] commit: express tree entry constants in terms of the_hash_algo

[brian m. carlson]

Specify these constants in terms of the size of the hash algorithm
currently in use.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 commit.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/commit.c b/commit.c
index 0c3b75aeff..ff05d04570 100644
--- a/commit.c
+++ b/commit.c
@@ -364,8 +364,8 @@ int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long s
 	struct object_id parent;
 	struct commit_list **pptr;
 	struct commit_graft *graft;
-	const int tree_entry_len = GIT_SHA1_HEXSZ + 5;
-	const int parent_entry_len = GIT_SHA1_HEXSZ + 7;
+	const int tree_entry_len = the_hash_algo->hexsz + 5;
+	const int parent_entry_len = the_hash_algo->hexsz + 7;
 
 	if (item->object.parsed)
 		return 0;

[PATCH 05/17] strbuf: allocate space with GIT_MAX_HEXSZ

[brian m. carlson]

In order to be sure we have enough space to use with any hash algorithm,
use GIT_MAX_HEXSZ to allocate space.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 strbuf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/strbuf.c b/strbuf.c
index b0716ac585..030556111d 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -921,7 +921,7 @@ void strbuf_add_unique_abbrev(struct strbuf *sb, const struct object_id *oid,
 			      int abbrev_len)
 {
 	int r;
-	strbuf_grow(sb, GIT_SHA1_HEXSZ + 1);
+	strbuf_grow(sb, GIT_MAX_HEXSZ + 1);
 	r = find_unique_abbrev_r(sb->buf + sb->len, oid, abbrev_len);
 	strbuf_setlen(sb, sb->len + r);
 }

[PATCH 06/17] sha1-name: use the_hash_algo when parsing object names

[brian m. carlson]

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 sha1-name.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/sha1-name.c b/sha1-name.c
index 60d9ef3c7e..ba6a5a689f 100644
--- a/sha1-name.c
+++ b/sha1-name.c
@@ -310,7 +310,7 @@ static int init_object_disambiguation(const char *name, int len,
 {
 	int i;
 
-	if (len < MINIMUM_ABBREV || len > GIT_SHA1_HEXSZ)
+	if (len < MINIMUM_ABBREV || len > the_hash_algo->hexsz)
 		return -1;
 
 	memset(ds, 0, sizeof(*ds));
@@ -576,6 +576,8 @@ int find_unique_abbrev_r(char *hex, const struct object_id *oid, int len)
 	struct disambiguate_state ds;
 	struct min_abbrev_data mad;
 	struct object_id oid_ret;
+	const unsigned hexsz = the_hash_algo->hexsz;
+
 	if (len < 0) {
 		unsigned long count = approximate_object_count();
 		/*
@@ -599,8 +601,8 @@ int find_unique_abbrev_r(char *hex, const struct object_id *oid, int len)
 	}
 
 	oid_to_hex_r(hex, oid);
-	if (len == GIT_SHA1_HEXSZ || !len)
-		return GIT_SHA1_HEXSZ;
+	if (len == hexsz || !len)
+		return hexsz;
 
 	mad.init_len = len;
 	mad.cur_len = len;
@@ -706,7 +708,7 @@ static int get_oid_basic(const char *str, int len, struct object_id *oid,
 	int refs_found = 0;
 	int at, reflog_len, nth_prior = 0;
 
-	if (len == GIT_SHA1_HEXSZ && !get_oid_hex(str, oid)) {
+	if (len == the_hash_algo->hexsz && !get_oid_hex(str, oid)) {
 		if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 			refs_found = dwim_ref(str, len, &tmp_oid, &real_ref);
 			if (refs_found > 0) {
@@ -750,7 +752,7 @@ static int get_oid_basic(const char *str, int len, struct object_id *oid,
 		int detached;
 
 		if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
-			detached = (buf.len == GIT_SHA1_HEXSZ && !get_oid_hex(buf.buf, oid));
+			detached = (buf.len == the_hash_algo->hexsz && !get_oid_hex(buf.buf, oid));
 			strbuf_release(&buf);
 			if (detached)
 				return 0;

[PATCH 07/17] commit: increase commit message buffer size

[brian m. carlson]

100 bytes is not sufficient to ensure we can write a commit message
buffer when using a 32-byte hash algorithm.  Increase the buffer size to
ensure we have sufficient space.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 refs/files-backend.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/refs/files-backend.c b/refs/files-backend.c
index a9a066dcfb..252f835bae 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -1587,7 +1587,7 @@ static int log_ref_write_fd(int fd, const struct object_id *old_oid,
 	char *logrec;
 
 	msglen = msg ? strlen(msg) : 0;
-	maxlen = strlen(committer) + msglen + 100;
+	maxlen = strlen(committer) + msglen + 200;
 	logrec = xmalloc(maxlen);
 	len = xsnprintf(logrec, maxlen, "%s %s %s\n",
 			oid_to_hex(old_oid),

Re: [PATCH 07/17] commit: increase commit message buffer size

[Derrick Stolee]

On 7/8/2018 7:36 PM, brian m. carlson wrote:
> 100 bytes is not sufficient to ensure we can write a commit message
> buffer when using a 32-byte hash algorithm.  Increase the buffer size to
> ensure we have sufficient space.
>
> Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
> ---
>   refs/files-backend.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/refs/files-backend.c b/refs/files-backend.c
> index a9a066dcfb..252f835bae 100644
> --- a/refs/files-backend.c
> +++ b/refs/files-backend.c
> @@ -1587,7 +1587,7 @@ static int log_ref_write_fd(int fd, const struct object_id *old_oid,
>   	char *logrec;
>   
>   	msglen = msg ? strlen(msg) : 0;
> -	maxlen = strlen(committer) + msglen + 100;
> +	maxlen = strlen(committer) + msglen + 200;
>   	logrec = xmalloc(maxlen);
>   	len = xsnprintf(logrec, maxlen, "%s %s %s\n",
>   			oid_to_hex(old_oid),

nit: 100 is not enough anymore, but wasn't a very descriptive value. 200 
may be enough now, but I'm not sure why.

Thanks,
-Stolee

Re: [PATCH 07/17] commit: increase commit message buffer size

[Stefan Beller]

On Mon, Jul 9, 2018 at 6:09 AM Derrick Stolee <stolee@gmail.com> wrote:
>
> On 7/8/2018 7:36 PM, brian m. carlson wrote:
> > 100 bytes is not sufficient to ensure we can write a commit message
> > buffer when using a 32-byte hash algorithm.  Increase the buffer size to
> > ensure we have sufficient space.
> >
> > Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
> > ---
> >   refs/files-backend.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/refs/files-backend.c b/refs/files-backend.c
> > index a9a066dcfb..252f835bae 100644
> > --- a/refs/files-backend.c
> > +++ b/refs/files-backend.c
> > @@ -1587,7 +1587,7 @@ static int log_ref_write_fd(int fd, const struct object_id *old_oid,
> >       char *logrec;
> >
> >       msglen = msg ? strlen(msg) : 0;
> > -     maxlen = strlen(committer) + msglen + 100;
> > +     maxlen = strlen(committer) + msglen + 200;
> >       logrec = xmalloc(maxlen);
> >       len = xsnprintf(logrec, maxlen, "%s %s %s\n",
> >                       oid_to_hex(old_oid),
>
> nit: 100 is not enough anymore, but wasn't a very descriptive value. 200
> may be enough now, but I'm not sure why.

That line was touched in by Michael in 7bd9bcf372d (refs: split filesystem-based
refs code into a new file, 2015-11-09) and before that by Ronnie in 2c6207abbd6
(refs.c: add a function to append a reflog entry to a fd, 2014-12-12)
and introduced
by Junio in 8ac65937d03 (Make sure we do not write bogus reflog
entries., 2007-01-26)
and it appears to me that 2*40 + 5 ought to be sufficient, but no
comments or commit
messages are found as to why we rather choose 100.

Re: [PATCH 07/17] commit: increase commit message buffer size

[Brandon Williams]

On 07/09, Stefan Beller wrote:
> On Mon, Jul 9, 2018 at 6:09 AM Derrick Stolee <stolee@gmail.com> wrote:
> >
> > On 7/8/2018 7:36 PM, brian m. carlson wrote:
> > > 100 bytes is not sufficient to ensure we can write a commit message
> > > buffer when using a 32-byte hash algorithm.  Increase the buffer size to
> > > ensure we have sufficient space.
> > >
> > > Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
> > > ---
> > >   refs/files-backend.c | 2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/refs/files-backend.c b/refs/files-backend.c
> > > index a9a066dcfb..252f835bae 100644
> > > --- a/refs/files-backend.c
> > > +++ b/refs/files-backend.c
> > > @@ -1587,7 +1587,7 @@ static int log_ref_write_fd(int fd, const struct object_id *old_oid,
> > >       char *logrec;
> > >
> > >       msglen = msg ? strlen(msg) : 0;
> > > -     maxlen = strlen(committer) + msglen + 100;
> > > +     maxlen = strlen(committer) + msglen + 200;
> > >       logrec = xmalloc(maxlen);
> > >       len = xsnprintf(logrec, maxlen, "%s %s %s\n",
> > >                       oid_to_hex(old_oid),
> >
> > nit: 100 is not enough anymore, but wasn't a very descriptive value. 200
> > may be enough now, but I'm not sure why.
> 
> That line was touched in by Michael in 7bd9bcf372d (refs: split filesystem-based
> refs code into a new file, 2015-11-09) and before that by Ronnie in 2c6207abbd6
> (refs.c: add a function to append a reflog entry to a fd, 2014-12-12)
> and introduced
> by Junio in 8ac65937d03 (Make sure we do not write bogus reflog
> entries., 2007-01-26)
> and it appears to me that 2*40 + 5 ought to be sufficient, but no
> comments or commit
> messages are found as to why we rather choose 100.

Whats the reason for not using a strbuf here so that we don't have to
play with magic numbers?

-- 
Brandon Williams

Re: [PATCH 07/17] commit: increase commit message buffer size

[Junio C Hamano]

Brandon Williams <bmwill@google.com> writes:

>> > > diff --git a/refs/files-backend.c b/refs/files-backend.c
>> > > index a9a066dcfb..252f835bae 100644
>> > > --- a/refs/files-backend.c
>> > > +++ b/refs/files-backend.c
>> > > @@ -1587,7 +1587,7 @@ static int log_ref_write_fd(int fd, const struct object_id *old_oid,
>> > >       char *logrec;
>> > >
>> > >       msglen = msg ? strlen(msg) : 0;
>> > > -     maxlen = strlen(committer) + msglen + 100;
>> > > +     maxlen = strlen(committer) + msglen + 200;
>> > >       logrec = xmalloc(maxlen);
>> > >       len = xsnprintf(logrec, maxlen, "%s %s %s\n",
>> > >                       oid_to_hex(old_oid),
>> >
>> > nit: 100 is not enough anymore, but wasn't a very descriptive value. 200
>> > may be enough now, but I'm not sure why.
>> 
>> That line was touched in by Michael in 7bd9bcf372d (refs: split filesystem-based
>> refs code into a new file, 2015-11-09) and before that by Ronnie in 2c6207abbd6
>> (refs.c: add a function to append a reflog entry to a fd, 2014-12-12)
>> and introduced
>> by Junio in 8ac65937d03 (Make sure we do not write bogus reflog
>> entries., 2007-01-26)
>> and it appears to me that 2*40 + 5 ought to be sufficient, but no
>> comments or commit
>> messages are found as to why we rather choose 100.
>
> Whats the reason for not using a strbuf here so that we don't have to
> play with magic numbers?

Quite a legitimate question.  

I suspect that the reason is because the code (even though it now
sits in a file that was relatively recently creted) predates either
the introduction or wide adoption of strbuf.

Back when 6de08ae6 ("Log ref updates to logs/refs/<ref>",
2006-05-17) was done, we already had strbuf.c, but it only had
read_line() and nothing else back then, so it wouldn't have been
possible to use a strbuf there.

Re: [PATCH 07/17] commit: increase commit message buffer size

[Brandon Williams]

On 07/09, Junio C Hamano wrote:
> Brandon Williams <bmwill@google.com> writes:
> 
> >> > > diff --git a/refs/files-backend.c b/refs/files-backend.c
> >> > > index a9a066dcfb..252f835bae 100644
> >> > > --- a/refs/files-backend.c
> >> > > +++ b/refs/files-backend.c
> >> > > @@ -1587,7 +1587,7 @@ static int log_ref_write_fd(int fd, const struct object_id *old_oid,
> >> > >       char *logrec;
> >> > >
> >> > >       msglen = msg ? strlen(msg) : 0;
> >> > > -     maxlen = strlen(committer) + msglen + 100;
> >> > > +     maxlen = strlen(committer) + msglen + 200;
> >> > >       logrec = xmalloc(maxlen);
> >> > >       len = xsnprintf(logrec, maxlen, "%s %s %s\n",
> >> > >                       oid_to_hex(old_oid),
> >> >
> >> > nit: 100 is not enough anymore, but wasn't a very descriptive value. 200
> >> > may be enough now, but I'm not sure why.
> >> 
> >> That line was touched in by Michael in 7bd9bcf372d (refs: split filesystem-based
> >> refs code into a new file, 2015-11-09) and before that by Ronnie in 2c6207abbd6
> >> (refs.c: add a function to append a reflog entry to a fd, 2014-12-12)
> >> and introduced
> >> by Junio in 8ac65937d03 (Make sure we do not write bogus reflog
> >> entries., 2007-01-26)
> >> and it appears to me that 2*40 + 5 ought to be sufficient, but no
> >> comments or commit
> >> messages are found as to why we rather choose 100.
> >
> > Whats the reason for not using a strbuf here so that we don't have to
> > play with magic numbers?
> 
> Quite a legitimate question.  
> 
> I suspect that the reason is because the code (even though it now
> sits in a file that was relatively recently creted) predates either
> the introduction or wide adoption of strbuf.
> 
> Back when 6de08ae6 ("Log ref updates to logs/refs/<ref>",
> 2006-05-17) was done, we already had strbuf.c, but it only had
> read_line() and nothing else back then, so it wouldn't have been
> possible to use a strbuf there.

Fair enough, having never working in the code back then I don't know
what life was like without strbuf.

-- 
Brandon Williams

Re: [PATCH 07/17] commit: increase commit message buffer size

[Junio C Hamano]

Derrick Stolee <stolee@gmail.com> writes:

> On 7/8/2018 7:36 PM, brian m. carlson wrote:
>> 100 bytes is not sufficient to ensure we can write a commit message
>> buffer when using a 32-byte hash algorithm.  Increase the buffer size to
>> ensure we have sufficient space.
>>
>> Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
>> ---
>>   refs/files-backend.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/refs/files-backend.c b/refs/files-backend.c
>> index a9a066dcfb..252f835bae 100644
>> --- a/refs/files-backend.c
>> +++ b/refs/files-backend.c
>> @@ -1587,7 +1587,7 @@ static int log_ref_write_fd(int fd, const struct object_id *old_oid,
>>   	char *logrec;
>>     	msglen = msg ? strlen(msg) : 0;
>> -	maxlen = strlen(committer) + msglen + 100;
>> +	maxlen = strlen(committer) + msglen + 200;
>>   	logrec = xmalloc(maxlen);
>>   	len = xsnprintf(logrec, maxlen, "%s %s %s\n",
>>   			oid_to_hex(old_oid),
>
> nit: 100 is not enough anymore, but wasn't a very descriptive
> value. 200 may be enough now, but I'm not sure why.

As Brandon alludes to downthread, we probably should use strbuf for
things like this these days, so a preliminary clean-up to do so is
probably a welcome change to sneak in and rebase this series on top
of.

"%s %s %s\n" with old and new commit object name and the message
will be "2 * len(hash_in_hex) + 4" bytes long (counting the three
whitespaces and the terminating NUL), and Shawn's original in
6de08ae6 ("Log ref updates to logs/refs/<ref>", 2006-05-17) actually
computed this one as "strlen(...) + 2*40+4".

100 was merely me being sloppier than Shawn at 8ac65937 ("Make sure
we do not write bogus reflog entries.", 2007-01-26), preferring
being sufficient over not wasting even a single byte.

Re: [PATCH 07/17] commit: increase commit message buffer size

[brian m. carlson]

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On Mon, Jul 09, 2018 at 10:45:33AM -0700, Junio C Hamano wrote:
> Derrick Stolee <stolee@gmail.com> writes:
> 
> > On 7/8/2018 7:36 PM, brian m. carlson wrote:
> >> diff --git a/refs/files-backend.c b/refs/files-backend.c
> >> index a9a066dcfb..252f835bae 100644
> >> --- a/refs/files-backend.c
> >> +++ b/refs/files-backend.c
> >> @@ -1587,7 +1587,7 @@ static int log_ref_write_fd(int fd, const struct object_id *old_oid,
> >>   	char *logrec;
> >>     	msglen = msg ? strlen(msg) : 0;
> >> -	maxlen = strlen(committer) + msglen + 100;
> >> +	maxlen = strlen(committer) + msglen + 200;
> >>   	logrec = xmalloc(maxlen);
> >>   	len = xsnprintf(logrec, maxlen, "%s %s %s\n",
> >>   			oid_to_hex(old_oid),
> >
> > nit: 100 is not enough anymore, but wasn't a very descriptive
> > value. 200 may be enough now, but I'm not sure why.

200 is definitely enough.  Suppose we had a message consisting entirely
of SHA-1 hashes (5, at 20 bytes a piece).  If our new hash is 32 bytes
long, then it would require at most 160 bytes.

I only noticed this because the old code segfaulted.  My approach to
using a 32-byte hash was to set it up, do some basic tests, find out
what crashed, and fix it.  Most of this series is the basics necessary
to get the most rudimentary functionality out of a 32-byte Git,
excluding the index pieces, which are necessarily inelegant.

I didn't include them because there are other ways to implement the
changes which are more elegant in some ways and less elegant in other
ways, and I want to think more about it before I send them in.

> As Brandon alludes to downthread, we probably should use strbuf for
> things like this these days, so a preliminary clean-up to do so is
> probably a welcome change to sneak in and rebase this series on top
> of.

Sure, I agree that would be a better change, and I'm happy to reroll
with that.
-- 
brian m. carlson: Houston, Texas, US
OpenPGP: https://keybase.io/bk2204

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Re: [PATCH 07/17] commit: increase commit message buffer size

[Junio C Hamano]

"brian m. carlson" <sandals@crustytoothpaste.net> writes:

>> As Brandon alludes to downthread, we probably should use strbuf for
>> things like this these days, so a preliminary clean-up to do so is
>> probably a welcome change to sneak in and rebase this series on top
>> of.
>
> Sure, I agree that would be a better change, and I'm happy to reroll
> with that.

Or we can do the clean-up after this 17-patch series settles, which
probably is a better order to do things.  It is usually better to
make a longer but more mechanical topic like this pass through the
system rather quickly, which tends to minimize disruption on other
topics.

Re: [PATCH 07/17] commit: increase commit message buffer size

[Ben Peart]

On 7/9/2018 7:39 PM, brian m. carlson wrote:
> On Mon, Jul 09, 2018 at 10:45:33AM -0700, Junio C Hamano wrote:
>> Derrick Stolee <stolee@gmail.com> writes:
>>
>>> On 7/8/2018 7:36 PM, brian m. carlson wrote:
>>>> diff --git a/refs/files-backend.c b/refs/files-backend.c
>>>> index a9a066dcfb..252f835bae 100644
>>>> --- a/refs/files-backend.c
>>>> +++ b/refs/files-backend.c
>>>> @@ -1587,7 +1587,7 @@ static int log_ref_write_fd(int fd, const struct object_id *old_oid,
>>>>    	char *logrec;
>>>>      	msglen = msg ? strlen(msg) : 0;
>>>> -	maxlen = strlen(committer) + msglen + 100;
>>>> +	maxlen = strlen(committer) + msglen + 200;
>>>>    	logrec = xmalloc(maxlen);
>>>>    	len = xsnprintf(logrec, maxlen, "%s %s %s\n",
>>>>    			oid_to_hex(old_oid),
>>>
>>> nit: 100 is not enough anymore, but wasn't a very descriptive
>>> value. 200 may be enough now, but I'm not sure why.
> 
> 200 is definitely enough.  Suppose we had a message consisting entirely
> of SHA-1 hashes (5, at 20 bytes a piece).  If our new hash is 32 bytes
> long, then it would require at most 160 bytes.
> 
> I only noticed this because the old code segfaulted.  My approach to
> using a 32-byte hash was to set it up, do some basic tests, find out
> what crashed, and fix it.  Most of this series is the basics necessary
> to get the most rudimentary functionality out of a 32-byte Git,
> excluding the index pieces, which are necessarily inelegant.
> 
> I didn't include them because there are other ways to implement the
> changes which are more elegant in some ways and less elegant in other
> ways, and I want to think more about it before I send them in.
> 
>> As Brandon alludes to downthread, we probably should use strbuf for
>> things like this these days, so a preliminary clean-up to do so is
>> probably a welcome change to sneak in and rebase this series on top
>> of.
> 
> Sure, I agree that would be a better change, and I'm happy to reroll
> with that.
> 

I've put together a patch to update log_ref_write_fd() to use strbuf and 
will submit it shortly.

Re: [PATCH 07/17] commit: increase commit message buffer size

[brian m. carlson]

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On Tue, Jul 10, 2018 at 02:08:28PM -0400, Ben Peart wrote:
> 
> 
> On 7/9/2018 7:39 PM, brian m. carlson wrote:
> > On Mon, Jul 09, 2018 at 10:45:33AM -0700, Junio C Hamano wrote:
> > > As Brandon alludes to downthread, we probably should use strbuf for
> > > things like this these days, so a preliminary clean-up to do so is
> > > probably a welcome change to sneak in and rebase this series on top
> > > of.
> > 
> > Sure, I agree that would be a better change, and I'm happy to reroll
> > with that.
> > 
> 
> I've put together a patch to update log_ref_write_fd() to use strbuf and
> will submit it shortly.

Excellent.  I'll drop this patch in that case.
-- 
brian m. carlson: Houston, Texas, US
OpenPGP: https://keybase.io/bk2204

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Re: [PATCH 07/17] commit: increase commit message buffer size

[Junio C Hamano]

"brian m. carlson" <sandals@crustytoothpaste.net> writes:

> On Tue, Jul 10, 2018 at 02:08:28PM -0400, Ben Peart wrote:
>> 
>> 
>> On 7/9/2018 7:39 PM, brian m. carlson wrote:
>> > On Mon, Jul 09, 2018 at 10:45:33AM -0700, Junio C Hamano wrote:
>> > > As Brandon alludes to downthread, we probably should use strbuf for
>> > > things like this these days, so a preliminary clean-up to do so is
>> > > probably a welcome change to sneak in and rebase this series on top
>> > > of.
>> > 
>> > Sure, I agree that would be a better change, and I'm happy to reroll
>> > with that.
>> > 
>> 
>> I've put together a patch to update log_ref_write_fd() to use strbuf and
>> will submit it shortly.
>
> Excellent.  I'll drop this patch in that case.

OK, thanks for working well together.  In the integration run I did
yesterday evening, this part was resolved by taking what Ben did,
dropping the s/100/200/ change from this series, and the result
looked reasonable, of course.

[PATCH 08/17] refs/files-backend: use the_hash_algo for writing refs

[brian m. carlson]

In order to ensure we write the correct amount, use the_hash_algo to
find the correct number of bytes for the current hash.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 refs/files-backend.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/refs/files-backend.c b/refs/files-backend.c
index 252f835bae..4a724f20a9 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -1676,7 +1676,7 @@ static int write_ref_to_lockfile(struct ref_lock *lock,
 		return -1;
 	}
 	fd = get_lock_file_fd(&lock->lk);
-	if (write_in_full(fd, oid_to_hex(oid), GIT_SHA1_HEXSZ) < 0 ||
+	if (write_in_full(fd, oid_to_hex(oid), the_hash_algo->hexsz) < 0 ||
 	    write_in_full(fd, &term, 1) < 0 ||
 	    close_ref_gently(lock) < 0) {
 		strbuf_addf(err,
@@ -3070,7 +3070,7 @@ static int files_reflog_expire(struct ref_store *ref_store,
 			rollback_lock_file(&reflog_lock);
 		} else if (update &&
 			   (write_in_full(get_lock_file_fd(&lock->lk),
-				oid_to_hex(&cb.last_kept_oid), GIT_SHA1_HEXSZ) < 0 ||
+				oid_to_hex(&cb.last_kept_oid), the_hash_algo->hexsz) < 0 ||
 			    write_str_in_full(get_lock_file_fd(&lock->lk), "\n") < 0 ||
 			    close_ref_gently(lock) < 0)) {
 			status |= error("couldn't write %s",

[PATCH 09/17] builtin/update-index: convert to using the_hash_algo

[brian m. carlson]

Switch from using GIT_SHA1_HEXSZ to the_hash_algo to make the parsing of
the index information hash independent.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 builtin/update-index.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/builtin/update-index.c b/builtin/update-index.c
index a8709a26ec..031cef5229 100644
--- a/builtin/update-index.c
+++ b/builtin/update-index.c
@@ -492,6 +492,7 @@ static void update_one(const char *path)
 
 static void read_index_info(int nul_term_line)
 {
+	const int hexsz = the_hash_algo->hexsz;
 	struct strbuf buf = STRBUF_INIT;
 	struct strbuf uq = STRBUF_INIT;
 	strbuf_getline_fn getline_fn;
@@ -529,7 +530,7 @@ static void read_index_info(int nul_term_line)
 		mode = ul;
 
 		tab = strchr(ptr, '\t');
-		if (!tab || tab - ptr < GIT_SHA1_HEXSZ + 1)
+		if (!tab || tab - ptr < hexsz + 1)
 			goto bad_line;
 
 		if (tab[-2] == ' ' && '0' <= tab[-1] && tab[-1] <= '3') {
@@ -542,8 +543,8 @@ static void read_index_info(int nul_term_line)
 			ptr = tab + 1; /* point at the head of path */
 		}
 
-		if (get_oid_hex(tab - GIT_SHA1_HEXSZ, &oid) ||
-			tab[-(GIT_SHA1_HEXSZ + 1)] != ' ')
+		if (get_oid_hex(tab - hexsz, &oid) ||
+			tab[-(hexsz + 1)] != ' ')
 			goto bad_line;
 
 		path_name = ptr;
@@ -571,7 +572,7 @@ static void read_index_info(int nul_term_line)
 			 * ptr[-1] points at tab,
 			 * ptr[-41] is at the beginning of sha1
 			 */
-			ptr[-(GIT_SHA1_HEXSZ + 2)] = ptr[-1] = 0;
+			ptr[-(hexsz + 2)] = ptr[-1] = 0;
 			if (add_cacheinfo(mode, &oid, path_name, stage))
 				die("git update-index: unable to update %s",
 				    path_name);

[PATCH 10/17] builtin/update-index: simplify parsing of cacheinfo

[brian m. carlson]

Switch from using get_oid_hex to parse_oid_hex to simplify pointer
operations and avoid the need for a hash-related constant.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 builtin/update-index.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/builtin/update-index.c b/builtin/update-index.c
index 031cef5229..3206c5ad45 100644
--- a/builtin/update-index.c
+++ b/builtin/update-index.c
@@ -827,6 +827,7 @@ static int parse_new_style_cacheinfo(const char *arg,
 {
 	unsigned long ul;
 	char *endp;
+	const char *p;
 
 	if (!arg)
 		return -1;
@@ -837,9 +838,9 @@ static int parse_new_style_cacheinfo(const char *arg,
 		return -1; /* not a new-style cacheinfo */
 	*mode = ul;
 	endp++;
-	if (get_oid_hex(endp, oid) || endp[GIT_SHA1_HEXSZ] != ',')
+	if (parse_oid_hex(endp, oid, &p) || *p != ',')
 		return -1;
-	*path = endp + GIT_SHA1_HEXSZ + 1;
+	*path = p + 1;
 	return 0;
 }
 

[PATCH 11/17] builtin/fmt-merge-msg: make hash independent

[brian m. carlson]

Convert several uses of GIT_SHA1_HEXSZ into references to the_hash_algo.
Switch other uses into a use of parse_oid_hex and uses of its computed
pointer.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 builtin/fmt-merge-msg.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/builtin/fmt-merge-msg.c b/builtin/fmt-merge-msg.c
index bd680be687..e8c13a2c03 100644
--- a/builtin/fmt-merge-msg.c
+++ b/builtin/fmt-merge-msg.c
@@ -108,14 +108,15 @@ static int handle_line(char *line, struct merge_parents *merge_parents)
 	struct string_list_item *item;
 	int pulling_head = 0;
 	struct object_id oid;
+	const unsigned hexsz = the_hash_algo->hexsz;
 
-	if (len < GIT_SHA1_HEXSZ + 3 || line[GIT_SHA1_HEXSZ] != '\t')
+	if (len < hexsz + 3 || line[hexsz] != '\t')
 		return 1;
 
-	if (starts_with(line + GIT_SHA1_HEXSZ + 1, "not-for-merge"))
+	if (starts_with(line + hexsz + 1, "not-for-merge"))
 		return 0;
 
-	if (line[GIT_SHA1_HEXSZ + 1] != '\t')
+	if (line[hexsz + 1] != '\t')
 		return 2;
 
 	i = get_oid_hex(line, &oid);
@@ -130,7 +131,7 @@ static int handle_line(char *line, struct merge_parents *merge_parents)
 
 	if (line[len - 1] == '\n')
 		line[len - 1] = 0;
-	line += GIT_SHA1_HEXSZ + 2;
+	line += hexsz + 2;
 
 	/*
 	 * At this point, line points at the beginning of comment e.g.
@@ -342,7 +343,7 @@ static void shortlog(const char *name,
 	const struct object_id *oid = &origin_data->oid;
 	int limit = opts->shortlog_len;
 
-	branch = deref_tag(parse_object(oid), oid_to_hex(oid), GIT_SHA1_HEXSZ);
+	branch = deref_tag(parse_object(oid), oid_to_hex(oid), the_hash_algo->hexsz);
 	if (!branch || branch->type != OBJ_COMMIT)
 		return;
 
@@ -545,6 +546,7 @@ static void find_merge_parents(struct merge_parents *result,
 		int len;
 		char *p = in->buf + pos;
 		char *newline = strchr(p, '\n');
+		const char *q;
 		struct object_id oid;
 		struct commit *parent;
 		struct object *obj;
@@ -552,10 +554,9 @@ static void find_merge_parents(struct merge_parents *result,
 		len = newline ? newline - p : strlen(p);
 		pos += len + !!newline;
 
-		if (len < GIT_SHA1_HEXSZ + 3 ||
-		    get_oid_hex(p, &oid) ||
-		    p[GIT_SHA1_HEXSZ] != '\t' ||
-		    p[GIT_SHA1_HEXSZ + 1] != '\t')
+		if (parse_oid_hex(p, &oid, &q) ||
+		    q[0] != '\t' ||
+		    q[1] != '\t')
 			continue; /* skip not-for-merge */
 		/*
 		 * Do not use get_merge_parent() here; we do not have

[PATCH 12/17] builtin/merge: switch to use the_hash_algo

[brian m. carlson]

Switch uses of GIT_SHA1_HEXSZ to use the_hash_algo instead.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 builtin/merge.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/builtin/merge.c b/builtin/merge.c
index 4a4c09496c..916c9f0569 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -1034,6 +1034,7 @@ static void handle_fetch_head(struct commit_list **remotes, struct strbuf *merge
 	const char *filename;
 	int fd, pos, npos;
 	struct strbuf fetch_head_file = STRBUF_INIT;
+	const unsigned hexsz = the_hash_algo->hexsz;
 
 	if (!merge_names)
 		merge_names = &fetch_head_file;
@@ -1059,16 +1060,16 @@ static void handle_fetch_head(struct commit_list **remotes, struct strbuf *merge
 		else
 			npos = merge_names->len;
 
-		if (npos - pos < GIT_SHA1_HEXSZ + 2 ||
+		if (npos - pos < hexsz + 2 ||
 		    get_oid_hex(merge_names->buf + pos, &oid))
 			commit = NULL; /* bad */
-		else if (memcmp(merge_names->buf + pos + GIT_SHA1_HEXSZ, "\t\t", 2))
+		else if (memcmp(merge_names->buf + pos + hexsz, "\t\t", 2))
 			continue; /* not-for-merge */
 		else {
-			char saved = merge_names->buf[pos + GIT_SHA1_HEXSZ];
-			merge_names->buf[pos + GIT_SHA1_HEXSZ] = '\0';
+			char saved = merge_names->buf[pos + hexsz];
+			merge_names->buf[pos + hexsz] = '\0';
 			commit = get_merge_parent(merge_names->buf + pos);
-			merge_names->buf[pos + GIT_SHA1_HEXSZ] = saved;
+			merge_names->buf[pos + hexsz] = saved;
 		}
 		if (!commit) {
 			if (ptr)

[PATCH 13/17] builtin/merge-recursive: make hash independent

[brian m. carlson]

Use GIT_MAX_HEXSZ instead of GIT_SHA1_HEXSZ for an allocation so that it
is sufficiently large.  Switch a comparison to use the_hash_algo to
determine the length of a hex object ID.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 builtin/merge-recursive.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/builtin/merge-recursive.c b/builtin/merge-recursive.c
index 0dd9021958..9b2f707c29 100644
--- a/builtin/merge-recursive.c
+++ b/builtin/merge-recursive.c
@@ -9,10 +9,10 @@ static const char builtin_merge_recursive_usage[] =
 
 static const char *better_branch_name(const char *branch)
 {
-	static char githead_env[8 + GIT_SHA1_HEXSZ + 1];
+	static char githead_env[8 + GIT_MAX_HEXSZ + 1];
 	char *name;
 
-	if (strlen(branch) != GIT_SHA1_HEXSZ)
+	if (strlen(branch) != the_hash_algo->hexsz)
 		return branch;
 	xsnprintf(githead_env, sizeof(githead_env), "GITHEAD_%s", branch);
 	name = getenv(githead_env);

[PATCH 14/17] diff: switch GIT_SHA1_HEXSZ to use the_hash_algo

[brian m. carlson]

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 diff.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/diff.c b/diff.c
index 639eb646b9..485ff6c264 100644
--- a/diff.c
+++ b/diff.c
@@ -3832,7 +3832,7 @@ static const char *diff_abbrev_oid(const struct object_id *oid, int abbrev)
 		char *hex = oid_to_hex(oid);
 		if (abbrev < 0)
 			abbrev = FALLBACK_DEFAULT_ABBREV;
-		if (abbrev > GIT_SHA1_HEXSZ)
+		if (abbrev > the_hash_algo->hexsz)
 			BUG("oid abbreviation out of range: %d", abbrev);
 		if (abbrev)
 			hex[abbrev] = '\0';
@@ -4947,7 +4947,7 @@ const char *diff_aligned_abbrev(const struct object_id *oid, int len)
 	const char *abbrev;
 
 	/* Do we want all 40 hex characters? */
-	if (len == GIT_SHA1_HEXSZ)
+	if (len == the_hash_algo->hexsz)
 		return oid_to_hex(oid);
 
 	/* An abbreviated value is fine, possibly followed by an ellipsis. */
@@ -4977,7 +4977,7 @@ const char *diff_aligned_abbrev(const struct object_id *oid, int len)
 	 * the automatic sizing is supposed to give abblen that ensures
 	 * uniqueness across all objects (statistically speaking).
 	 */
-	if (abblen < GIT_SHA1_HEXSZ - 3) {
+	if (abblen < the_hash_algo->hexsz - 3) {
 		static char hex[GIT_MAX_HEXSZ + 1];
 		if (len < abblen && abblen <= len + 2)
 			xsnprintf(hex, sizeof(hex), "%s%.*s", abbrev, len+3-abblen, "..");

[PATCH 15/17] log-tree: switch GIT_SHA1_HEXSZ to the_hash_algo->hexsz

[brian m. carlson]

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 log-tree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/log-tree.c b/log-tree.c
index d3a43e29cd..9655de8ad7 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -545,7 +545,7 @@ void show_log(struct rev_info *opt)
 	struct strbuf msgbuf = STRBUF_INIT;
 	struct log_info *log = opt->loginfo;
 	struct commit *commit = log->commit, *parent = log->parent;
-	int abbrev_commit = opt->abbrev_commit ? opt->abbrev : GIT_SHA1_HEXSZ;
+	int abbrev_commit = opt->abbrev_commit ? opt->abbrev : the_hash_algo->hexsz;
 	const char *extra_headers = opt->extra_headers;
 	struct pretty_print_context ctx = {0};
 

[PATCH 16/17] sha1-file: convert constants to uses of the_hash_algo

[brian m. carlson]

Convert one use of 20 and several uses of GIT_SHA1_HEXSZ into references
to the_hash_algo.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 sha1-file.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/sha1-file.c b/sha1-file.c
index de4839e634..1f66b9594f 100644
--- a/sha1-file.c
+++ b/sha1-file.c
@@ -336,7 +336,7 @@ int raceproof_create_file(const char *path, create_file_fn fn, void *cb)
 static void fill_sha1_path(struct strbuf *buf, const unsigned char *sha1)
 {
 	int i;
-	for (i = 0; i < 20; i++) {
+	for (i = 0; i < the_hash_algo->rawsz; i++) {
 		static char hex[] = "0123456789abcdef";
 		unsigned int val = sha1[i];
 		strbuf_addch(buf, hex[val >> 4]);
@@ -1473,7 +1473,7 @@ void *read_object_with_reference(const struct object_id *oid,
 		}
 		ref_length = strlen(ref_type);
 
-		if (ref_length + GIT_SHA1_HEXSZ > isize ||
+		if (ref_length + the_hash_algo->hexsz > isize ||
 		    memcmp(buffer, ref_type, ref_length) ||
 		    get_oid_hex((char *) buffer + ref_length, &actual_oid)) {
 			free(buffer);
@@ -2062,9 +2062,9 @@ int for_each_file_in_obj_subdir(unsigned int subdir_nr,
 		namelen = strlen(de->d_name);
 		strbuf_setlen(path, baselen);
 		strbuf_add(path, de->d_name, namelen);
-		if (namelen == GIT_SHA1_HEXSZ - 2 &&
+		if (namelen == the_hash_algo->hexsz - 2 &&
 		    !hex_to_bytes(oid.hash + 1, de->d_name,
-				  GIT_SHA1_RAWSZ - 1)) {
+				  the_hash_algo->rawsz - 1)) {
 			if (obj_cb) {
 				r = obj_cb(&oid, path->buf, data);
 				if (r)

[PATCH 17/17] pretty: switch hard-coded constants to the_hash_algo

[brian m. carlson]

Switch several hard-coded constants into expressions based either on
GIT_MAX_HEXSZ or the_hash_algo.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 pretty.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pretty.c b/pretty.c
index 703fa6ff7b..b0e653ff25 100644
--- a/pretty.c
+++ b/pretty.c
@@ -1575,7 +1575,7 @@ static void pp_header(struct pretty_print_context *pp,
 		}
 
 		if (starts_with(line, "parent ")) {
-			if (linelen != 48)
+			if (linelen != the_hash_algo->hexsz + 8)
 				die("bad parent line in commit");
 			continue;
 		}
@@ -1583,7 +1583,7 @@ static void pp_header(struct pretty_print_context *pp,
 		if (!parents_shown) {
 			unsigned num = commit_list_count(commit->parents);
 			/* with enough slop */
-			strbuf_grow(sb, num * 50 + 20);
+			strbuf_grow(sb, num * (GIT_MAX_HEXSZ + 10) + 20);
 			add_merge_info(pp, sb, commit);
 			parents_shown = 1;
 		}

Re: [PATCH 00/17] object_id part 14

[Jacob Keller]

On Sun, Jul 8, 2018 at 4:39 PM brian m. carlson
<sandals@crustytoothpaste.net> wrote:
>
> This is the fourteenth series of patches to switch to using struct
> object_id and the_hash_algo.  This series converts several core pieces
> to use struct object_id, including the oid* and hex functions.
>
> All of these patches have been tested with both SHA-1 and a 256-bit
> hash.
>

I read through the series, and didn't spot anything odd, except for
the question about reasoning for why we use memcmp directly over using
hashcmp. I don't think that's any sort of blocker, it just seemed an
odd decision to me.

Thanks,
Jake

Re: [PATCH 00/17] object_id part 14

[Derrick Stolee]

On 7/8/2018 11:12 PM, Jacob Keller wrote:
> On Sun, Jul 8, 2018 at 4:39 PM brian m. carlson
> <sandals@crustytoothpaste.net> wrote:
>> This is the fourteenth series of patches to switch to using struct
>> object_id and the_hash_algo.  This series converts several core pieces
>> to use struct object_id, including the oid* and hex functions.
>>
>> All of these patches have been tested with both SHA-1 and a 256-bit
>> hash.
>>
> I read through the series, and didn't spot anything odd, except for
> the question about reasoning for why we use memcmp directly over using
> hashcmp. I don't think that's any sort of blocker, it just seemed an
> odd decision to me.

I also read through the series and only found the 100/200 constants 
confusing. Not worth blocking on, but I'm CC'ing Michael Haggerty to 
comment if he knows how the magic 100 was computed.

Thanks,
-Stolee

Re: [PATCH 00/17] object_id part 14

[Michael Haggerty]

On Mon, Jul 9, 2018 at 6:15 AM Derrick Stolee <stolee@gmail.com> wrote:
> On 7/8/2018 11:12 PM, Jacob Keller wrote:
> > On Sun, Jul 8, 2018 at 4:39 PM brian m. carlson
> > <sandals@crustytoothpaste.net> wrote:
> >> This is the fourteenth series of patches to switch to using struct
> >> object_id and the_hash_algo.  This series converts several core pieces
> >> to use struct object_id, including the oid* and hex functions.
> >>
> >> All of these patches have been tested with both SHA-1 and a 256-bit
> >> hash.
> >>
> > I read through the series, and didn't spot anything odd, except for
> > the question about reasoning for why we use memcmp directly over using
> > hashcmp. I don't think that's any sort of blocker, it just seemed an
> > odd decision to me.
>
> I also read through the series and only found the 100/200 constants
> confusing. Not worth blocking on, but I'm CC'ing Michael Haggerty to
> comment if he knows how the magic 100 was computed.

The magic 100 blames back to our chief magician, Junio:

    8ac65937d0 Make sure we do not write bogus reflog entries. (2007-01-26)

Since then, as far as I can tell, it's just been copy-pasted forward.
It would be easy to compute it precisely based on the length of the
two OIDs, represented as hex strings, plus the few extra characters in
the format string.

Michael

Re: [PATCH 00/17] object_id part 14

[Junio C Hamano]

Michael Haggerty <mhagger@alum.mit.edu> writes:

> The magic 100 blames back to our chief magician, Junio:
>
>     8ac65937d0 Make sure we do not write bogus reflog entries. (2007-01-26)

Yup, guilty as charged.

cf. <xmqqva9oe20y.fsf@gitster-ct.c.googlers.com>

    "%s %s %s\n" with old and new commit object name and the message
    will be "2 * len(hash_in_hex) + 4" bytes long (counting the three
    whitespaces and the terminating NUL), and Shawn's original in
    6de08ae6 ("Log ref updates to logs/refs/<ref>", 2006-05-17) actually
    computed this one as "strlen(...) + 2*40+4".

    100 was merely me being sloppier than Shawn at 8ac65937 ("Make sure
    we do not write bogus reflog entries.", 2007-01-26), preferring
    being sufficient over not wasting even a single byte.