[Qemu-devel] Re: [PATCH] linux-user: Linux kernel's fchmodat and faccessat have three args (no 4th arg)

[Aurelien Jarno <aurelien@aurel32.net>]

On Sun, Apr 19, 2009 at 04:39:02PM +0900, takasi-y@ops.dti.ne.jp wrote:
> In Linux kernel, fchmodat() and faccessat() take tree args.
> 4th value <int flags> is only processed by libc.
> 
> Signed-off-by: Takashi YOSHII <takasi-y@ops.dti.ne.jp>
> ---

Thanks, applied.

> > Good catch. It seems that it's also the case for faccessat. Could you
> > please follow-up with a patch fixing both? Thanks.
> Oh, that's right. I have added it.
> 
> I use 0 for the flag value to host libc's faccessat(),
> This is because faccessat() in libc attempt to call kernel faccessat() only if
>  ((flag == 0 || ((flag & ~AT_EACCESS) == 0 && ! __libc_enable_secure))
> , otherwise access() or fstat64 is used.
> # Only be checked with sysdeps/unix/sysv/linux/faccessat.c in eglibc-2.8.
> 
> Three cases below have been tested (flag!=0 case is out of scope)
>  faccessat(AT_FDCWD, "testfile", F_OK|W_OK, 0)
>  - ENOENT without testfile
>  - EACCESS with testfile 0400
>  - ok with testfile 0600
> on x86_64 host(Debian 5.0.1) + sh4a target(GentooLinux glibc2.8).
> 
> /yoshii
> ---
>  linux-user/syscall.c |   17 ++++++++---------
>  1 files changed, 8 insertions(+), 9 deletions(-)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index ffdbb98..0bc9902 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -303,15 +303,15 @@ static int sys_getcwd1(char *buf, size_t size)
>   */
>  
>  #ifdef TARGET_NR_faccessat
> -static int sys_faccessat(int dirfd, const char *pathname, int mode, int flags)
> +static int sys_faccessat(int dirfd, const char *pathname, int mode)
>  {
> -  return (faccessat(dirfd, pathname, mode, flags));
> +  return (faccessat(dirfd, pathname, mode, 0));
>  }
>  #endif
>  #ifdef TARGET_NR_fchmodat
> -static int sys_fchmodat(int dirfd, const char *pathname, mode_t mode, int flags)
> +static int sys_fchmodat(int dirfd, const char *pathname, mode_t mode)
>  {
> -  return (fchmodat(dirfd, pathname, mode, flags));
> +  return (fchmodat(dirfd, pathname, mode, 0));
>  }
>  #endif
>  #if defined(TARGET_NR_fchownat) && defined(USE_UID16)
> @@ -425,11 +425,10 @@ static int sys_utimensat(int dirfd, const char *pathname,
>   * Try direct syscalls instead
>   */
>  #if defined(TARGET_NR_faccessat) && defined(__NR_faccessat)
> -_syscall4(int,sys_faccessat,int,dirfd,const char *,pathname,int,mode,int,flags)
> +_syscall3(int,sys_faccessat,int,dirfd,const char *,pathname,int,mode)
>  #endif
>  #if defined(TARGET_NR_fchmodat) && defined(__NR_fchmodat)
> -_syscall4(int,sys_fchmodat,int,dirfd,const char *,pathname,
> -          mode_t,mode,int,flags)
> +_syscall3(int,sys_fchmodat,int,dirfd,const char *,pathname, mode_t,mode)
>  #endif
>  #if defined(TARGET_NR_fchownat) && defined(__NR_fchownat) && defined(USE_UID16)
>  _syscall5(int,sys_fchownat,int,dirfd,const char *,pathname,
> @@ -4218,7 +4217,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
>      case TARGET_NR_faccessat:
>          if (!(p = lock_user_string(arg2)))
>              goto efault;
> -        ret = get_errno(sys_faccessat(arg1, p, arg3, arg4));
> +        ret = get_errno(sys_faccessat(arg1, p, arg3));
>          unlock_user(p, arg2, 0);
>          break;
>  #endif
> @@ -4944,7 +4943,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
>      case TARGET_NR_fchmodat:
>          if (!(p = lock_user_string(arg2)))
>              goto efault;
> -        ret = get_errno(sys_fchmodat(arg1, p, arg3, arg4));
> +        ret = get_errno(sys_fchmodat(arg1, p, arg3));
>          unlock_user(p, arg2, 0);
>          break;
>  #endif
> -- 
> 1.5.6.5
> 
> 

-- 
Aurelien Jarno	                        GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net