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, see
  17    <http://www.gnu.org/licenses/>.
  18
  19    As a special exception, if you link the code in this file with
  20    files compiled with a GNU compiler to produce an executable,
  21    that does not cause the resulting executable to be covered by
  22    the GNU Lesser General Public License.  This exception does not
  23    however invalidate any other reasons why the executable file
  24    might be covered by the GNU Lesser General Public License.
  25    This exception applies to code released by its copyright holders
  26    in files containing the exception.  */
  27
  28 #include <stdlib.h>
  29 #include "libioP.h"
  30 #include <fcntl.h>
  31
  32 #ifdef _LIBC
  33 # include <shlib-compat.h>
  34 #endif
  35
  36 #ifndef _IO_fcntl
  37 #ifdef _LIBC
  38 #define _IO_fcntl __fcntl
  39 #else
  40 #define _IO_fcntl fcntl
  41 #endif
  42 #endif
  43
  44 _IO_FILE *
  45 _IO_new_fdopen (fd, mode)
  46      int fd;
  47      const char *mode;
  48 {
  49   int read_write;
  50   int posix_mode = 0;
  51   struct locked_FILE
  52   {
  53     struct _IO_FILE_plus fp;
  54 #ifdef _IO_MTSAFE_IO
  55     _IO_lock_t lock;
  56 #endif
  57     struct _IO_wide_data wd;
  58   } *new_f;
  59   int fd_flags;
  60   int i;
  61   int use_mmap = 0;
  62
  63   switch (*mode)
  64     {
  65     case 'r':
  66       read_write = _IO_NO_WRITES;
  67       break;
  68     case 'w':
  69       read_write = _IO_NO_READS;
  70       break;
  71     case 'a':
  72       posix_mode = O_APPEND;
  73       read_write = _IO_NO_READS|_IO_IS_APPENDING;
  74       break;
  75     default:
  76       MAYBE_SET_EINVAL;
  77       return NULL;
  78   }
  79   for (i = 1; i < 5; ++i)
  80     {
  81       switch (*++mode)
  82         {
  83         case '\0':
  84           break;
  85         case '+':
  86           read_write &= _IO_IS_APPENDING;
  87           break;
  88         case 'm':
  89           use_mmap = 1;
  90           continue;
  91         case 'x':
  92         case 'b':
  93         default:
  94           /* Ignore */
  95           continue;
  96         }
  97       break;
  98     }
  99 #ifdef F_GETFL
 100   fd_flags = _IO_fcntl (fd, F_GETFL);
 101 #ifndef O_ACCMODE
 102 #define O_ACCMODE (O_RDONLY|O_WRONLY|O_RDWR)
 103 #endif
 104   if (fd_flags == -1)
 105     return NULL;
 106
 107   if (((fd_flags & O_ACCMODE) == O_RDONLY && !(read_write & _IO_NO_WRITES))
 108       || ((fd_flags & O_ACCMODE) == O_WRONLY && !(read_write & _IO_NO_READS)))
 109     {
 110       MAYBE_SET_EINVAL;
 111       return NULL;
 112     }
 113
 114   /* The May 93 draft of P1003.4/D14.1 (redesignated as 1003.1b)
 115      [System Application Program Interface (API) Amendment 1:
 116      Realtime Extensions], Rationale B.8.3.3
 117      Open a Stream on a File Descriptor says:
 118
 119          Although not explicitly required by POSIX.1, a good
 120          implementation of append ("a") mode would cause the
 121          O_APPEND flag to be set.
 122
 123      (Historical implementations [such as Solaris2] do a one-time
 124      seek in fdopen.)
 125
 126      However, we do not turn O_APPEND off if the mode is "w" (even
 127      though that would seem consistent) because that would be more
 128      likely to break historical programs.
 129      */
 130   if ((posix_mode & O_APPEND) && !(fd_flags & O_APPEND))
 131     {
 132 #ifdef F_SETFL
 133       if (_IO_fcntl (fd, F_SETFL, fd_flags | O_APPEND) == -1)
 134 #endif
 135         return NULL;
 136     }
 137 #endif
 138
 139   new_f = (struct locked_FILE *) malloc (sizeof (struct locked_FILE));
 140   if (new_f == NULL)
 141     return NULL;
 142 #ifdef _IO_MTSAFE_IO
 143   new_f->fp.file._lock = &new_f->lock;
 144 #endif
 145   /* Set up initially to use the `maybe_mmap' jump tables rather than using
 146      __fopen_maybe_mmap to do it, because we need them in place before we
 147      call _IO_file_attach or else it will allocate a buffer immediately.  */
 148   _IO_no_init (&new_f->fp.file, 0, 0, &new_f->wd,
 149 #ifdef _G_HAVE_MMAP
 150                (use_mmap && (read_write & _IO_NO_WRITES))
 151                ? &_IO_wfile_jumps_maybe_mmap :
 152 #endif
 153                &_IO_wfile_jumps);
 154   _IO_JUMPS (&new_f->fp) =
 155 #ifdef _G_HAVE_MMAP
 156     (use_mmap && (read_write & _IO_NO_WRITES)) ? &_IO_file_jumps_maybe_mmap :
 157 #endif
 158       &_IO_file_jumps;
 159   INTUSE(_IO_file_init) (&new_f->fp);
 160 #if  !_IO_UNIFIED_JUMPTABLES
 161   new_f->fp.vtable = NULL;
 162 #endif
 163   if (INTUSE(_IO_file_attach) ((_IO_FILE *) &new_f->fp, fd) == NULL)
 164     {
 165       INTUSE(_IO_setb) (&new_f->fp.file, NULL, NULL, 0);
 166       INTUSE(_IO_un_link) (&new_f->fp);
 167       free (new_f);
 168       return NULL;
 169     }
 170   new_f->fp.file._flags &= ~_IO_DELETE_DONT_CLOSE;
 171
 172   _IO_mask_flags (&new_f->fp.file, read_write,
 173                   _IO_NO_READS+_IO_NO_WRITES+_IO_IS_APPENDING);
 174
 175   return &new_f->fp.file;
 176 }
 177 INTDEF2(_IO_new_fdopen, _IO_fdopen)
 178
 179 strong_alias (_IO_new_fdopen, __new_fdopen)
 180 versioned_symbol (libc, _IO_new_fdopen, _IO_fdopen, GLIBC_2_1);
 181 versioned_symbol (libc, __new_fdopen, fdopen, GLIBC_2_1);