* [PATCH] libc_fatal: Add comment regarding alloca usage.
@ 2023-06-20 18:41 Joe Simmons-Talbott
2023-07-05 15:16 ` Joe Simmons-Talbott
0 siblings, 1 reply; 2+ messages in thread
From: Joe Simmons-Talbott @ 2023-06-20 18:41 UTC (permalink / raw)
To: libc-alpha; +Cc: Joe Simmons-Talbott
Since __libc_message is only used in a few places and always with a
const char * format string and a small fixed-sized struct the usage of
alloca here is safe. Add a comment explaining this for both alloca
usages.
---
sysdeps/posix/libc_fatal.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/sysdeps/posix/libc_fatal.c b/sysdeps/posix/libc_fatal.c
index 70edcc10c1..caa01bcbf6 100644
--- a/sysdeps/posix/libc_fatal.c
+++ b/sysdeps/posix/libc_fatal.c
@@ -100,6 +100,9 @@ __libc_message (const char *fmt, ...)
cp = next;
}
+ /* alloca is safe here since the current usage of __libc_message uses
+ relatively short const char * format strings and a small fixed size
+ struct. */
struct str_list *newp = alloca (sizeof (struct str_list));
newp->str = str;
newp->len = len;
@@ -110,6 +113,9 @@ __libc_message (const char *fmt, ...)
if (nlist > 0)
{
+ /* alloca is safe here since the current usage of __libc_message uses
+ relatively short const char * format strings and a small fixed size
+ struct. */
struct iovec *iov = alloca (nlist * sizeof (struct iovec));
ssize_t total = 0;
--
2.39.2
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] libc_fatal: Add comment regarding alloca usage.
2023-06-20 18:41 [PATCH] libc_fatal: Add comment regarding alloca usage Joe Simmons-Talbott
@ 2023-07-05 15:16 ` Joe Simmons-Talbott
0 siblings, 0 replies; 2+ messages in thread
From: Joe Simmons-Talbott @ 2023-07-05 15:16 UTC (permalink / raw)
To: libc-alpha
On Tue, Jun 20, 2023 at 02:41:54PM -0400, Joe Simmons-Talbott wrote:
> Since __libc_message is only used in a few places and always with a
> const char * format string and a small fixed-sized struct the usage of
> alloca here is safe. Add a comment explaining this for both alloca
> usages.
Ping.
Thanks,
Joe
> ---
> sysdeps/posix/libc_fatal.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/sysdeps/posix/libc_fatal.c b/sysdeps/posix/libc_fatal.c
> index 70edcc10c1..caa01bcbf6 100644
> --- a/sysdeps/posix/libc_fatal.c
> +++ b/sysdeps/posix/libc_fatal.c
> @@ -100,6 +100,9 @@ __libc_message (const char *fmt, ...)
> cp = next;
> }
>
> + /* alloca is safe here since the current usage of __libc_message uses
> + relatively short const char * format strings and a small fixed size
> + struct. */
> struct str_list *newp = alloca (sizeof (struct str_list));
> newp->str = str;
> newp->len = len;
> @@ -110,6 +113,9 @@ __libc_message (const char *fmt, ...)
>
> if (nlist > 0)
> {
> + /* alloca is safe here since the current usage of __libc_message uses
> + relatively short const char * format strings and a small fixed size
> + struct. */
> struct iovec *iov = alloca (nlist * sizeof (struct iovec));
> ssize_t total = 0;
>
> --
> 2.39.2
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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