Re: [PATCHv3 2/2] builtin/commit.c: switch to xstrfmt(), instead of snprintf,
Am 13.01.2017 um 18:58 schrieb Elia Pinto:
Show 60 quoted lines
> In this patch, instead of using xnprintf instead of snprintf, which asserts
> that we don't truncate, we are switching to dynamic allocation with xstrfmt(),
> , so we can avoid dealing with magic numbers in the code and reduce the cognitive burden from
> the programmers, because they no longer have to count bytes needed for static allocation.
> As a side effect of this patch we have also reduced the snprintf() calls, that may silently truncate
> results if the programmer is not careful.
>
> Helped-by: Junio C Hamano <gitster@pobox.com>
> Helped-by: Jeff King <peff@peff.net>
> Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
> ---
> This is the third version of the patch.
>
> Changes from the first version: I have split the original commit in two, as discussed here
> http://public-inbox.org/git/20161213132717.42965-1-gitter.spiros@gmail.com/.
>
> Changes from the second version:
> - Changed the commit message to clarify the purpose of the patch (
> as suggested by Junio)
> https://public-inbox.org/git/xmqqtw95mfo3.fsf@gitster.mtv.corp.google.com/T/#m2e6405a8a78a8ca1ed770614c91398290574c4a1
>
>
>
> builtin/commit.c | 10 ++++------
> 1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/builtin/commit.c b/builtin/commit.c
> index 09bcc0f13..37228330c 100644
> --- a/builtin/commit.c
> +++ b/builtin/commit.c
> @@ -1526,12 +1526,10 @@ static int git_commit_config(const char *k, const char *v, void *cb)
> static int run_rewrite_hook(const unsigned char *oldsha1,
> const unsigned char *newsha1)
> {
> - /* oldsha1 SP newsha1 LF NUL */
> - static char buf[2*40 + 3];
> + char *buf;
> struct child_process proc = CHILD_PROCESS_INIT;
> const char *argv[3];
> int code;
> - size_t n;
>
> argv[0] = find_hook("post-rewrite");
> if (!argv[0])
> @@ -1547,11 +1545,11 @@ static int run_rewrite_hook(const unsigned char *oldsha1,
> code = start_command(&proc);
> if (code)
> return code;
> - n = snprintf(buf, sizeof(buf), "%s %s\n",
> - sha1_to_hex(oldsha1), sha1_to_hex(newsha1));
> + buf = xstrfmt("%s %s\n", sha1_to_hex(oldsha1), sha1_to_hex(newsha1));
> sigchain_push(SIGPIPE, SIG_IGN);
> - write_in_full(proc.in, buf, n);
> + write_in_full(proc.in, buf, strlen(buf));
> close(proc.in);
> + free(buf);
> sigchain_pop(SIGPIPE);
> return finish_command(&proc);
> }
> Perhaps I missed it from the discussion, but why not use strbuf? It
would avoid counting the generated string's length. That's probably
not going to make a measurable difference performance-wise, but it's
easy to avoid and doesn't even take up more lines:
---
builtin/commit.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/builtin/commit.c b/builtin/commit.c
index 711f96cc43..73bb72016f 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1525,12 +1525,10 @@ static int git_commit_config(const char *k, const char *v, void *cb)
static int run_rewrite_hook(const unsigned char *oldsha1,
const unsigned char *newsha1)
{
- /* oldsha1 SP newsha1 LF NUL */
- static char buf[2*40 + 3];
+ struct strbuf sb = STRBUF_INIT;
struct child_process proc = CHILD_PROCESS_INIT;
const char *argv[3];
int code;
- size_t n;
argv[0] = find_hook("post-rewrite");
if (!argv[0])
@@ -1546,11 +1544,11 @@ static int run_rewrite_hook(const unsigned char *oldsha1,
code = start_command(&proc);
if (code)
return code;
- n = snprintf(buf, sizeof(buf), "%s %s\n",
- sha1_to_hex(oldsha1), sha1_to_hex(newsha1));
+ strbuf_addf(&sb, "%s %s\n", sha1_to_hex(oldsha1), sha1_to_hex(newsha1));
sigchain_push(SIGPIPE, SIG_IGN);
- write_in_full(proc.in, buf, n);
+ write_in_full(proc.in, sb.buf, sb.len);
close(proc.in);
+ strbuf_release(&sb);
sigchain_pop(SIGPIPE);
return finish_command(&proc);
}
--
2.11.0
René Scharfe <l.s.r@web.de>