Re: [PATCH 57/67] receive-pack: simplify keep_arg computation

[Jeff King]

On Fri, Sep 18, 2015 at 02:43:56PM -0400, Eric Sunshine wrote:

> On Tue, Sep 15, 2015 at 12:10 PM, Jeff King  wrote:
> > To generate "--keep=receive-pack $pid on $host", we write
> > progressively into a single buffer, which requires keeping
> > track of how much we've written so far. But since the result
> > is destined to go into our argv array, we can simply use
> > argv_array_pushf.
> >
> > Unfortunately we still have to have a static buffer for the
> 
> s/static/fixed-size/ maybe?

Thanks, will change.

The term "static buffer overflow" seems stuck in my head (and you can
find references via google), even though it does not make sense at all.
In C terms, a stack buffer is really an "auto", but I guess "auto buffer
overflow" does not have as nice a ring to it.

I agree that "fixed-size" is a lot less confusing, and corrected several
such cases before sent out the series. I guess I missed one (I'll grep
for others).

-Peff
--
To unsubscribe from this list: send the line "unsubscribe git" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH 57/67] receive-pack: simplify keep_arg computation

[Eric Sunshine]

On Tue, Sep 15, 2015 at 12:10 PM, Jeff King  wrote:
> To generate "--keep=receive-pack $pid on $host", we write
> progressively into a single buffer, which requires keeping
> track of how much we've written so far. But since the result
> is destined to go into our argv array, we can simply use
> argv_array_pushf.
>
> Unfortunately we still have to have a static buffer for the

s/static/fixed-size/ maybe?

> gethostname() call, but at least it now doesn't involve any
> extra size computation. And as a bonus, we drop an sprintf
> and a strcpy call.
>
> Signed-off-by: Jeff King 
> ---
> diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
> index 8b50e48..2c82274 100644
> --- a/builtin/receive-pack.c
> +++ b/builtin/receive-pack.c
> @@ -1524,15 +1524,18 @@ static const char *unpack(int err_fd, struct 
> shallow_info *si)
> if (status)
> return "unpack-objects abnormal exit";
> } else {
> -   int s;
> -   char keep_arg[256];
> -
> -   s = sprintf(keep_arg, "--keep=receive-pack %"PRIuMAX" on ", 
> (uintmax_t) getpid());
> -   if (gethostname(keep_arg + s, sizeof(keep_arg) - s))
> -   strcpy(keep_arg + s, "localhost");
> +   char hostname[256];
>
> argv_array_pushl(, "index-pack",
> -"--stdin", hdr_arg, keep_arg, NULL);
> +"--stdin", hdr_arg, NULL);
> +
> +   if (gethostname(hostname, sizeof(hostname)))
> +   xsnprintf(hostname, sizeof(hostname), "localhost");
> +   argv_array_pushf(,
> +"--keep=receive-pack %"PRIuMAX" on %s",
> +(uintmax_t)getpid(),
> +hostname);
> +
> if (fsck_objects)
> argv_array_pushf(, "--strict%s",
> fsck_msg_types.buf);
> --
> 2.6.0.rc2.408.ga2926b9
--
To unsubscribe from this list: send the line "unsubscribe git" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[PATCH 57/67] receive-pack: simplify keep_arg computation

[Jeff King]

To generate "--keep=receive-pack $pid on $host", we write
progressively into a single buffer, which requires keeping
track of how much we've written so far. But since the result
is destined to go into our argv array, we can simply use
argv_array_pushf.

Unfortunately we still have to have a static buffer for the
gethostname() call, but at least it now doesn't involve any
extra size computation. And as a bonus, we drop an sprintf
and a strcpy call.

Signed-off-by: Jeff King 
---
 builtin/receive-pack.c | 17 ++---
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index 8b50e48..2c82274 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -1524,15 +1524,18 @@ static const char *unpack(int err_fd, struct 
shallow_info *si)
if (status)
return "unpack-objects abnormal exit";
} else {
-   int s;
-   char keep_arg[256];
-
-   s = sprintf(keep_arg, "--keep=receive-pack %"PRIuMAX" on ", 
(uintmax_t) getpid());
-   if (gethostname(keep_arg + s, sizeof(keep_arg) - s))
-   strcpy(keep_arg + s, "localhost");
+   char hostname[256];
 
argv_array_pushl(, "index-pack",
-"--stdin", hdr_arg, keep_arg, NULL);
+"--stdin", hdr_arg, NULL);
+
+   if (gethostname(hostname, sizeof(hostname)))
+   xsnprintf(hostname, sizeof(hostname), "localhost");
+   argv_array_pushf(,
+"--keep=receive-pack %"PRIuMAX" on %s",
+(uintmax_t)getpid(),
+hostname);
+
if (fsck_objects)
argv_array_pushf(, "--strict%s",
fsck_msg_types.buf);
-- 
2.6.0.rc2.408.ga2926b9

--
To unsubscribe from this list: send the line "unsubscribe git" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html