sysdeps/unix/sysv/linux/mkdirat.c

   1 /* Copyright (C) 2005, 2006 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <errno.h>
  20 #include <fcntl.h>
  21 #include <stddef.h>
  22 #include <stdio.h>
  23 #include <string.h>
  24 #include <sys/stat.h>
  25 #include <kernel-features.h>
  26 #include <sysdep-cancel.h>
  27
  28
  29 /* Create a new directory with permission bits MODE.  But interpret
  30    relative PATH names relative to the directory associated with FD.  */
  31 int
  32 mkdirat (fd, file, mode)
  33      int fd;
  34      const char *file;
  35      mode_t mode;
  36 {
  37   int res;
  38
  39 #ifdef __NR_mkdirat
  40 #  ifndef __ASSUME_ATFCTS
  41   if (__have_atfcts >= 0)
  42 # endif
  43     {
  44       res = INLINE_SYSCALL (mkdirat, 3, fd, file, mode);
  45 # ifndef __ASSUME_ATFCTS
  46       if (res == -1 && res == ENOSYS)
  47         __have_atfcts = -1;
  48       else
  49 # endif
  50         return res;
  51     }
  52 #endif
  53
  54 #ifndef __ASSUME_ATFCTS
  55   char *buf = NULL;
  56
  57   if (fd != AT_FDCWD && file[0] != '/')
  58     {
  59       size_t filelen = strlen (file);
  60       static const char procfd[] = "/proc/self/fd/%d/%s";
  61       /* Buffer for the path name we are going to use.  It consists of
  62          - the string /proc/self/fd/
  63          - the file descriptor number
  64          - the file name provided.
  65          The final NUL is included in the sizeof.   A bit of overhead
  66          due to the format elements compensates for possible negative
  67          numbers.  */
  68       size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
  69       buf = alloca (buflen);
  70
  71       __snprintf (buf, buflen, procfd, fd, file);
  72       file = buf;
  73     }
  74
  75   INTERNAL_SYSCALL_DECL (err);
  76   res = INTERNAL_SYSCALL (mkdir, err, 2, file, mode);
  77
  78   if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (res, err), 0))
  79     {
  80       __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (res, err), fd, buf);
  81       res = -1;
  82     }
  83
  84   return res;
  85 #endif
  86 }