sysdeps/unix/sysv/linux/unlinkat.c

   1 /* unlinkat -- Remove a link by relative name.
   2    Copyright (C) 2005 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <stddef.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <sysdep.h>
  27 #include <unistd.h>
  28
  29
  30 /* Remove the link named NAME.  */
  31 int
  32 unlinkat (fd, file, flag)
  33      int fd;
  34      const char *file;
  35      int flag;
  36 {
  37   if (flag & ~AT_REMOVEDIR)
  38     {
  39       __set_errno (EINVAL);
  40       return -1;
  41     }
  42
  43   char *buf = NULL;
  44
  45   if (fd != AT_FDCWD && file[0] != '/')
  46     {
  47       size_t filelen = strlen (file);
  48       static const char procfd[] = "/proc/self/fd/%d/%s";
  49       /* Buffer for the path name we are going to use.  It consists of
  50          - the string /proc/self/fd/
  51          - the file descriptor number
  52          - the file name provided.
  53          The final NUL is included in the sizeof.   A bit of overhead
  54          due to the format elements compensates for possible negative
  55          numbers.  */
  56       size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
  57       buf = __alloca (buflen);
  58
  59       __snprintf (buf, buflen, procfd, fd, file);
  60       file = buf;
  61     }
  62
  63   int result;
  64   INTERNAL_SYSCALL_DECL (err);
  65
  66   if (flag & AT_REMOVEDIR)
  67     result = INTERNAL_SYSCALL (rmdir, err, 1, file);
  68   else
  69     result = INTERNAL_SYSCALL (unlink, err, 1, file);
  70
  71   if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 0))
  72     {
  73       __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), fd, buf);
  74       result = -1;
  75     }
  76
  77   return result;
  78 }