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glibc  2.9
Functions
fchmodat.c File Reference
#include <errno.h>
#include <fcntl.h>
#include <stddef.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <alloca.h>
#include <kernel-features.h>
#include <sysdep.h>

Go to the source code of this file.

Functions

int fchmodat (int fd, const char *file, mode_t mode, int flag)

Function Documentation

int fchmodat ( int  fd,
const char *  file,
mode_t  mode,
int  flag 
)

Definition at line 32 of file fchmodat.c.

{
  if (flag & ~AT_SYMLINK_NOFOLLOW)
    {
      __set_errno (EINVAL);
      return -1;
    }
#ifndef __NR_lchmod         /* Linux so far has no lchmod syscall.  */
  if (flag & AT_SYMLINK_NOFOLLOW)
    {
      __set_errno (ENOTSUP);
      return -1;
    }
#endif

  int result;

#ifdef __NR_fchmodat
# ifndef __ASSUME_ATFCTS
  if (__have_atfcts >= 0)
# endif
    {
      result = INLINE_SYSCALL (fchmodat, 3, fd, file, mode);
# ifndef __ASSUME_ATFCTS
      if (result == -1 && errno == ENOSYS)
       __have_atfcts = -1;
      else
# endif
       return result;
    }
#endif

#ifndef __ASSUME_ATFCTS
  char *buf = NULL;

  if (fd != AT_FDCWD && file[0] != '/')
    {
      size_t filelen = strlen (file);
      static const char procfd[] = "/proc/self/fd/%d/%s";
      /* Buffer for the path name we are going to use.  It consists of
        - the string /proc/self/fd/
        - the file descriptor number
        - the file name provided.
        The final NUL is included in the sizeof.   A bit of overhead
        due to the format elements compensates for possible negative
        numbers.  */
      size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
      buf = alloca (buflen);

      __snprintf (buf, buflen, procfd, fd, file);
      file = buf;
    }

  INTERNAL_SYSCALL_DECL (err);

# ifdef __NR_lchmod
  if (flag & AT_SYMLINK_NOFOLLOW)
    result = INTERNAL_SYSCALL (lchmod, err, 2, file, mode);
  else
# endif
    result = INTERNAL_SYSCALL (chmod, err, 2, file, mode);

  if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 0))
    {
      __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), fd, buf);
      result = -1;
    }

  return result;
#endif
}

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