sysdeps/unix/sysv/linux/renameat.c

   1 /* Copyright (C) 2005, 2006, 2009 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, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <fcntl.h>
  20 #include <stdio.h>
  21 #include <string.h>
  22 #include <kernel-features.h>
  23 #include <sysdep.h>
  24
  25
  26 #ifndef __ASSUME_ATFCTS
  27 void
  28 attribute_hidden
  29 __atfct_seterrno_2 (int errval, int fd1, const char *buf1, int fd2,
  30                     const char *buf2)
  31 {
  32   if (buf1 != NULL || buf2 != NULL)
  33     {
  34       struct stat64 st;
  35
  36       if (errval == ENOTDIR)
  37         {
  38           /* This can mean either the file descriptor is invalid or
  39              /proc is not mounted.  */
  40           if (buf1 != NULL)
  41             {
  42               if (__fxstat64 (_STAT_VER, fd1, &st) != 0)
  43                 /* errno is already set correctly.  */
  44                 return;
  45
  46               /* If /proc is not mounted there is nothing we can do.  */
  47               if (S_ISDIR (st.st_mode)
  48                   && (__xstat64 (_STAT_VER, "/proc/self/fd", &st) != 0
  49                       || !S_ISDIR (st.st_mode)))
  50                 {
  51                   errval = ENOSYS;
  52                   goto out;
  53                 }
  54             }
  55
  56           if (buf2 != NULL)
  57             {
  58               if (__fxstat64 (_STAT_VER, fd2, &st) != 0)
  59                 /* errno is already set correctly.  */
  60                 return;
  61
  62               /* If /proc is not mounted there is nothing we can do.  */
  63               if (S_ISDIR (st.st_mode)
  64                   && (__xstat64 (_STAT_VER, "/proc/self/fd", &st) != 0
  65                       || !S_ISDIR (st.st_mode)))
  66                 errval = ENOSYS;
  67             }
  68         }
  69       else if (errval == ENOENT)
  70         {
  71           /* This could mean the file descriptor is not valid.  We
  72              reuse BUF for the stat call.  Find the slash after the
  73              file descriptor number.  */
  74           if (buf1 != NULL)
  75             {
  76               *(char *) strchr (buf1 + sizeof "/proc/self/fd", '/') = '\0';
  77
  78               int e = __lxstat64 (_STAT_VER, buf1, &st);
  79               if ((e == -1 && errno == ENOENT)
  80                   ||(e == 0 && !S_ISLNK (st.st_mode)))
  81                 {
  82                   errval = EBADF;
  83                   goto out;
  84                 }
  85             }
  86
  87           if (buf2 != NULL)
  88             {
  89               *(char *) strchr (buf2 + sizeof "/proc/self/fd", '/') = '\0';
  90
  91               int e = __lxstat64 (_STAT_VER, buf2, &st);
  92               if ((e == -1 && errno == ENOENT)
  93                   ||(e == 0 && !S_ISLNK (st.st_mode)))
  94                 errval = EBADF;
  95             }
  96         }
  97     }
  98
  99  out:
 100   __set_errno (errval);
 101 }
 102 #endif
 103
 104
 105 /* Rename the file OLD relative to OLDFD to NEW relative to NEWFD.  */
 106 int
 107 renameat (oldfd, old, newfd, new)
 108      int oldfd;
 109      const char *old;
 110      int newfd;
 111      const char *new;
 112 {
 113   int result;
 114
 115 #ifdef __NR_renameat
 116 # ifndef __ASSUME_ATFCTS
 117   if (__have_atfcts >= 0)
 118 # endif
 119     {
 120       result = INLINE_SYSCALL (renameat, 4, oldfd, old, newfd, new);
 121 # ifndef __ASSUME_ATFCTS
 122       if (result == -1 && errno == ENOSYS)
 123         __have_atfcts = -1;
 124       else
 125 # endif
 126         return result;
 127     }
 128 #endif
 129
 130 #ifndef __ASSUME_ATFCTS
 131   static const char procfd[] = "/proc/self/fd/%d/%s";
 132   char *bufold = NULL;
 133
 134   if (oldfd != AT_FDCWD && old[0] != '/')
 135     {
 136       size_t filelen = strlen (old);
 137       if (__builtin_expect (filelen == 0, 0))
 138         {
 139           __set_errno (ENOENT);
 140           return -1;
 141         }
 142
 143       /* Buffer for the path name we are going to use.  It consists of
 144          - the string /proc/self/fd/
 145          - the file descriptor number
 146          - the file name provided.
 147          The final NUL is included in the sizeof.   A bit of overhead
 148          due to the format elements compensates for possible negative
 149          numbers.  */
 150       size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
 151       bufold = alloca (buflen);
 152
 153       __snprintf (bufold, buflen, procfd, oldfd, old);
 154       old = bufold;
 155     }
 156
 157   char *bufnew = NULL;
 158
 159   if (newfd != AT_FDCWD && new[0] != '/')
 160     {
 161       size_t filelen = strlen (new);
 162       if (__builtin_expect (filelen == 0, 0))
 163         {
 164           __set_errno (ENOENT);
 165           return -1;
 166         }
 167
 168       /* Buffer for the path name we are going to use.  It consists of
 169          - the string /proc/self/fd/
 170          - the file descriptor number
 171          - the file name provided.
 172          The final NUL is included in the sizeof.   A bit of overhead
 173          due to the format elements compensates for possible negative
 174          numbers.  */
 175       size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
 176       bufnew = alloca (buflen);
 177
 178       __snprintf (bufnew, buflen, procfd, newfd, new);
 179       new = bufnew;
 180     }
 181
 182   INTERNAL_SYSCALL_DECL (err);
 183
 184   result = INTERNAL_SYSCALL (rename, err, 2, old,  new);
 185
 186   if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 0))
 187     {
 188       __atfct_seterrno_2 (INTERNAL_SYSCALL_ERRNO (result, err), newfd, bufnew,
 189                           oldfd, bufold);
 190       result = -1;
 191     }
 192
 193   return result;
 194 #endif
 195 }