[v3,1/2] linux: wait4: Fix incorrect return value comparison
Commit Message
Patch 600f00b "linux: Use long time_t for wait4/getrusage" introduced
two bugs:
- The usage32 struct was set if the wait4 syscall had an error.
- For 32-bit systems the usage struct was set even if it was specified
as NULL.
This patch fixes the two issues.
---
sysdeps/unix/sysv/linux/wait4.c | 32 ++++++++++++++++++++------------
1 file changed, 20 insertions(+), 12 deletions(-)
Comments
On 09/04/2020 17:11, Alistair Francis via Libc-alpha wrote:
> Patch 600f00b "linux: Use long time_t for wait4/getrusage" introduced
> two bugs:
> - The usage32 struct was set if the wait4 syscall had an error.
> - For 32-bit systems the usage struct was set even if it was specified
> as NULL.
>
> This patch fixes the two issues.
Ok with the changes below.
> ---
> sysdeps/unix/sysv/linux/wait4.c | 32 ++++++++++++++++++++------------
> 1 file changed, 20 insertions(+), 12 deletions(-)
>
> diff --git a/sysdeps/unix/sysv/linux/wait4.c b/sysdeps/unix/sysv/linux/wait4.c
> index d14bd4da27..21eb154b72 100644
> --- a/sysdeps/unix/sysv/linux/wait4.c
> +++ b/sysdeps/unix/sysv/linux/wait4.c
> @@ -29,14 +29,18 @@ __wait4_time64 (pid_t pid, int *stat_loc, int options, struct __rusage64 *usage)
> # if __KERNEL_OLD_TIMEVAL_MATCHES_TIMEVAL64
> return SYSCALL_CANCEL (wait4, pid, stat_loc, options, usage);
> # else
> - struct __rusage32 usage32;
> - pid_t ret = SYSCALL_CANCEL (wait4, pid, stat_loc, options, &usage32);
> -
> - if (ret != 0)
> - return ret;
> + pid_t ret;
>
> if (usage != NULL)
> - rusage32_to_rusage64 (&usage32, usage);
> + {
> + struct __rusage32 usage32;
> + ret = SYSCALL_CANCEL (wait4, pid, stat_loc, options, &usage32);
Indentation seems off.
> +
> + if (ret > 0)
> + rusage32_to_rusage64 (&usage32, usage);> + }
> + else
> + ret = SYSCALL_CANCEL (wait4, pid, stat_loc, options, NULL);
I think there is no much gain in optimizing stack usage here,
I would prefer to simplify to just:
struct __rusage32 usage32;
ret = SYSCALL_CANCEL (wait4, pid, stat_loc, options,
usage != NULL ? &usage32 : NULL);
if (ret > 0 && usage != NULL)
rusage32_to_rusage64 (&usage32, usage);
>
> return ret;
> # endif
> @@ -114,15 +118,19 @@ libc_hidden_def (__wait4_time64)
> pid_t
> __wait4 (pid_t pid, int *stat_loc, int options, struct rusage *usage)
> {
> - pid_t ret ;
> - struct __rusage64 usage64;
> + pid_t ret;
>
> - ret = __wait4_time64 (pid, stat_loc, options, &usage64);
> + if (usage != NULL)
> + {
> + struct __rusage64 usage64;
>
> - if (ret != 0)
> - return ret;
> + ret = __wait4_time64 (pid, stat_loc, options, &usage64);
>
> - rusage64_to_rusage (&usage64, usage);
> + if (ret > 0)
> + rusage64_to_rusage (&usage64, usage);
> + }
> + else
> + ret = __wait4_time64 (pid, stat_loc, options, NULL);
>
> return ret;
> }
>
Same as before:
struct __rusage64 usage64;
ret = __wait4_time64 (pid, stat_loc, options,
usage != NULL ? &usage64 : NULL);
if (ret > 0 && usage != 0)
rusage64_to_rusage (&usage64, usage);
@@ -29,14 +29,18 @@ __wait4_time64 (pid_t pid, int *stat_loc, int options, struct __rusage64 *usage)
# if __KERNEL_OLD_TIMEVAL_MATCHES_TIMEVAL64
return SYSCALL_CANCEL (wait4, pid, stat_loc, options, usage);
# else
- struct __rusage32 usage32;
- pid_t ret = SYSCALL_CANCEL (wait4, pid, stat_loc, options, &usage32);
-
- if (ret != 0)
- return ret;
+ pid_t ret;
if (usage != NULL)
- rusage32_to_rusage64 (&usage32, usage);
+ {
+ struct __rusage32 usage32;
+ ret = SYSCALL_CANCEL (wait4, pid, stat_loc, options, &usage32);
+
+ if (ret > 0)
+ rusage32_to_rusage64 (&usage32, usage);
+ }
+ else
+ ret = SYSCALL_CANCEL (wait4, pid, stat_loc, options, NULL);
return ret;
# endif
@@ -114,15 +118,19 @@ libc_hidden_def (__wait4_time64)
pid_t
__wait4 (pid_t pid, int *stat_loc, int options, struct rusage *usage)
{
- pid_t ret ;
- struct __rusage64 usage64;
+ pid_t ret;
- ret = __wait4_time64 (pid, stat_loc, options, &usage64);
+ if (usage != NULL)
+ {
+ struct __rusage64 usage64;
- if (ret != 0)
- return ret;
+ ret = __wait4_time64 (pid, stat_loc, options, &usage64);
- rusage64_to_rusage (&usage64, usage);
+ if (ret > 0)
+ rusage64_to_rusage (&usage64, usage);
+ }
+ else
+ ret = __wait4_time64 (pid, stat_loc, options, NULL);
return ret;
}