sysdeps/unix/sysv/linux/unlinkat.c

   1 /* unlinkat -- Remove a link by relative name.
   2    Copyright (C) 2005, 2006 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 #include <kernel-features.h>
  29
  30
  31 /* Remove the link named NAME.  */
  32 int
  33 unlinkat (fd, file, flag)
  34      int fd;
  35      const char *file;
  36      int flag;
  37 {
  38   int result;
  39
  40 #ifdef __NR_unlinkat
  41 # ifndef __ASSUME_ATFCTS
  42   if (__have_atfcts >= 0)
  43 # endif
  44     {
  45       result = INLINE_SYSCALL (unlinkat, 3, fd, file, flag);
  46 # ifndef __ASSUME_ATFCTS
  47       if (result == -1 && errno == ENOSYS)
  48         __have_atfcts = -1;
  49       else
  50 # endif
  51         return result;
  52     }
  53 #endif
  54
  55 #ifndef __ASSUME_ATFCTS
  56   if (flag & ~AT_REMOVEDIR)
  57     {
  58       __set_errno (EINVAL);
  59       return -1;
  60     }
  61
  62   char *buf = NULL;
  63
  64   if (fd != AT_FDCWD && file[0] != '/')
  65     {
  66       size_t filelen = strlen (file);
  67       static const char procfd[] = "/proc/self/fd/%d/%s";
  68       /* Buffer for the path name we are going to use.  It consists of
  69          - the string /proc/self/fd/
  70          - the file descriptor number
  71          - the file name provided.
  72          The final NUL is included in the sizeof.   A bit of overhead
  73          due to the format elements compensates for possible negative
  74          numbers.  */
  75       size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
  76       buf = __alloca (buflen);
  77
  78       __snprintf (buf, buflen, procfd, fd, file);
  79       file = buf;
  80     }
  81
  82   INTERNAL_SYSCALL_DECL (err);
  83
  84   if (flag & AT_REMOVEDIR)
  85     result = INTERNAL_SYSCALL (rmdir, err, 1, file);
  86   else
  87     result = INTERNAL_SYSCALL (unlink, err, 1, file);
  88
  89   if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 0))
  90     {
  91       __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), fd, buf);
  92       result = -1;
  93     }
  94
  95   return result;
  96 #endif
  97 }