Hi Alex,
On 2/7/21 12:43 PM, Alejandro Colomar wrote:
> It's been 6 years since execveat(2) was added to the kernel,
> and there's still no glibc wrapper. Let's document the kernel
> syscall prototype.
>
> I reported a bug against glibc requesting a wrapper;
> when glibc adds the wrapper, this commit should probably be
> reverted.
Thanks for filing the glibc bug.
I've applied this patch. Thanks!
Cheers,
Michael
> ......
>
> .../linux$ grep_syscall execveat
> fs/exec.c:2062:
> SYSCALL_DEFINE5(execveat,
> int, fd, const char __user *, filename,
> const char __user *const __user *, argv,
> const char __user *const __user *, envp,
> int, flags)
> fs/exec.c:2083:
> COMPAT_SYSCALL_DEFINE5(execveat, int, fd,
> const char __user *, filename,
> const compat_uptr_t __user *, argv,
> const compat_uptr_t __user *, envp,
> int, flags)
> include/linux/compat.h:815:
> asmlinkage long compat_sys_execveat(int dfd, const char __user *filename,
> const compat_uptr_t __user *argv,
> const compat_uptr_t __user *envp, int flags);
> include/linux/syscalls.h:980:
> asmlinkage long sys_execveat(int dfd, const char __user *filename,
> const char __user *const __user *argv,
> const char __user *const __user *envp, int flags);
> .../linux$
>
> function grep_syscall()
> {
> if ! [ -v 1 ]; then
> >&2 echo "Usage: ${FUNCNAME[0]} <syscall>";
> return ${EX_USAGE};
> fi
>
> find * -type f \
> |grep '\.c$' \
> |sort -V \
> |xargs pcregrep -Mn "(?s)^\w*SYSCALL_DEFINE.\(${1},.*?\)" \
> |sed -E 's/^[^:]+:[0-9]+:/&\n/';
>
> find * -type f \
> |grep '\.[ch]$' \
> |sort -V \
> |xargs pcregrep -Mn "(?s)^asmlinkage\s+[\w\s]+\**sys_${1}\s*\(.*?\)" \
> |sed -E 's/^[^:]+:[0-9]+:/&\n/';
> }
>
> Glibc bug: <https://sourceware.org/bugzilla/show_bug.cgi?id=27364>
> Signed-off-by: Alejandro Colomar <alx.manpages@xxxxxxxxx>
> ---
> man2/execveat.2 | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/man2/execveat.2 b/man2/execveat.2
> index 02d9c7331..d1ce4bee1 100644
> --- a/man2/execveat.2
> +++ b/man2/execveat.2
> @@ -31,7 +31,7 @@ execveat \- execute program relative to a directory file descriptor
> .B #include <unistd.h>
> .PP
> .BI "int execveat(int " dirfd ", const char *" pathname ,
> -.BI " char *const " argv "[], char *const " envp [],
> +.BI " const char *const " argv "[], const char *const " envp [],
> .BI " int " flags );
> .fi
> .PP
>
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
