libio/iofdopen.c

   1 /* Copyright (C) 1993,1994,1997,1998,1999,2000,2002,2003,2010,2012
   2         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    As a special exception, if you link the code in this file with
  21    files compiled with a GNU compiler to produce an executable,
  22    that does not cause the resulting executable to be covered by
  23    the GNU Lesser General Public License.  This exception does not
  24    however invalidate any other reasons why the executable file
  25    might be covered by the GNU Lesser General Public License.
  26    This exception applies to code released by its copyright holders
  27    in files containing the exception.  */
  28
  29 #include <stdlib.h>
  30 #include "libioP.h"
  31 #include <fcntl.h>
  32
  33 #ifdef _LIBC
  34 # include <shlib-compat.h>
  35 #endif
  36
  37 #ifndef _IO_fcntl
  38 #ifdef _LIBC
  39 #define _IO_fcntl __fcntl
  40 #else
  41 #define _IO_fcntl fcntl
  42 #endif
  43 #endif
  44
  45 _IO_FILE *
  46 _IO_new_fdopen (fd, mode)
  47      int fd;
  48      const char *mode;
  49 {
  50   int read_write;
  51   int posix_mode = 0;
  52   struct locked_FILE
  53   {
  54     struct _IO_FILE_plus fp;
  55 #ifdef _IO_MTSAFE_IO
  56     _IO_lock_t lock;
  57 #endif
  58     struct _IO_wide_data wd;
  59   } *new_f;
  60   int fd_flags;
  61   int i;
  62   int use_mmap = 0;
  63
  64   switch (*mode)
  65     {
  66     case 'r':
  67       read_write = _IO_NO_WRITES;
  68       break;
  69     case 'w':
  70       read_write = _IO_NO_READS;
  71       break;
  72     case 'a':
  73       posix_mode = O_APPEND;
  74       read_write = _IO_NO_READS|_IO_IS_APPENDING;
  75       break;
  76     default:
  77       MAYBE_SET_EINVAL;
  78       return NULL;
  79   }
  80   for (i = 1; i < 5; ++i)
  81     {
  82       switch (*++mode)
  83         {
  84         case '\0':
  85           break;
  86         case '+':
  87           read_write &= _IO_IS_APPENDING;
  88           break;
  89         case 'm':
  90           use_mmap = 1;
  91           continue;
  92         case 'x':
  93         case 'b':
  94         default:
  95           /* Ignore */
  96           continue;
  97         }
  98       break;
  99     }
 100 #ifdef F_GETFL
 101   fd_flags = _IO_fcntl (fd, F_GETFL);
 102 #ifndef O_ACCMODE
 103 #define O_ACCMODE (O_RDONLY|O_WRONLY|O_RDWR)
 104 #endif
 105   if (fd_flags == -1)
 106     return NULL;
 107
 108   if (((fd_flags & O_ACCMODE) == O_RDONLY && !(read_write & _IO_NO_WRITES))
 109       || ((fd_flags & O_ACCMODE) == O_WRONLY && !(read_write & _IO_NO_READS)))
 110     {
 111       MAYBE_SET_EINVAL;
 112       return NULL;
 113     }
 114
 115   /* The May 93 draft of P1003.4/D14.1 (redesignated as 1003.1b)
 116      [System Application Program Interface (API) Amendment 1:
 117      Realtime Extensions], Rationale B.8.3.3
 118      Open a Stream on a File Descriptor says:
 119
 120          Although not explicitly required by POSIX.1, a good
 121          implementation of append ("a") mode would cause the
 122          O_APPEND flag to be set.
 123
 124      (Historical implementations [such as Solaris2] do a one-time
 125      seek in fdopen.)
 126
 127      However, we do not turn O_APPEND off if the mode is "w" (even
 128      though that would seem consistent) because that would be more
 129      likely to break historical programs.
 130      */
 131   if ((posix_mode & O_APPEND) && !(fd_flags & O_APPEND))
 132     {
 133 #ifdef F_SETFL
 134       if (_IO_fcntl (fd, F_SETFL, fd_flags | O_APPEND) == -1)
 135 #endif
 136         return NULL;
 137     }
 138 #endif
 139
 140   new_f = (struct locked_FILE *) malloc (sizeof (struct locked_FILE));
 141   if (new_f == NULL)
 142     return NULL;
 143 #ifdef _IO_MTSAFE_IO
 144   new_f->fp.file._lock = &new_f->lock;
 145 #endif
 146   /* Set up initially to use the `maybe_mmap' jump tables rather than using
 147      __fopen_maybe_mmap to do it, because we need them in place before we
 148      call _IO_file_attach or else it will allocate a buffer immediately.  */
 149   _IO_no_init (&new_f->fp.file, 0, 0, &new_f->wd,
 150 #ifdef _G_HAVE_MMAP
 151                (use_mmap && (read_write & _IO_NO_WRITES))
 152                ? &_IO_wfile_jumps_maybe_mmap :
 153 #endif
 154                &_IO_wfile_jumps);
 155   _IO_JUMPS (&new_f->fp) =
 156 #ifdef _G_HAVE_MMAP
 157     (use_mmap && (read_write & _IO_NO_WRITES)) ? &_IO_file_jumps_maybe_mmap :
 158 #endif
 159       &_IO_file_jumps;
 160   INTUSE(_IO_file_init) (&new_f->fp);
 161 #if  !_IO_UNIFIED_JUMPTABLES
 162   new_f->fp.vtable = NULL;
 163 #endif
 164   if (INTUSE(_IO_file_attach) ((_IO_FILE *) &new_f->fp, fd) == NULL)
 165     {
 166       INTUSE(_IO_setb) (&new_f->fp.file, NULL, NULL, 0);
 167       INTUSE(_IO_un_link) (&new_f->fp);
 168       free (new_f);
 169       return NULL;
 170     }
 171   new_f->fp.file._flags &= ~_IO_DELETE_DONT_CLOSE;
 172
 173   _IO_mask_flags (&new_f->fp.file, read_write,
 174                   _IO_NO_READS+_IO_NO_WRITES+_IO_IS_APPENDING);
 175
 176   return &new_f->fp.file;
 177 }
 178 INTDEF2(_IO_new_fdopen, _IO_fdopen)
 179
 180 strong_alias (_IO_new_fdopen, __new_fdopen)
 181 versioned_symbol (libc, _IO_new_fdopen, _IO_fdopen, GLIBC_2_1);
 182 versioned_symbol (libc, __new_fdopen, fdopen, GLIBC_2_1);