libio/iofdopen.c

   1 /*
   2 Copyright (C) 1993, 1994 Free Software Foundation
   3
   4 This file is part of the GNU IO Library.  This library is free
   5 software; you can redistribute it and/or modify it under the
   6 terms of the GNU General Public License as published by the
   7 Free Software Foundation; either version 2, or (at your option)
   8 any later version.
   9
  10 This 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
  13 GNU General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with this library; see the file COPYING.  If not, write to the Free
  17 Software Foundation, 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  18
  19 As a special exception, if you link this library with files
  20 compiled with a GNU compiler to produce an executable, this does not cause
  21 the resulting executable to be covered by the GNU General Public License.
  22 This exception does not however invalidate any other reasons why
  23 the executable file might be covered by the GNU General Public License. */
  24
  25 #ifdef __STDC__
  26 #include <stdlib.h>
  27 #endif
  28 #include "libioP.h"
  29 #include <fcntl.h>
  30
  31 #ifndef _IO_fcntl
  32 #define _IO_fcntl fcntl
  33 #endif
  34
  35 _IO_FILE *
  36 _IO_fdopen (fd, mode)
  37      int fd;
  38      const char *mode;
  39 {
  40   int read_write;
  41   int posix_mode = 0;
  42   struct locked_FILE
  43   {
  44     struct _IO_FILE_plus fp;
  45 #ifdef _IO_MTSAFE_IO
  46     _IO_lock_t lock;
  47 #endif
  48   } *new_f;
  49   int fd_flags;
  50
  51   switch (*mode++)
  52     {
  53     case 'r':
  54       read_write = _IO_NO_WRITES;
  55       break;
  56     case 'w':
  57       read_write = _IO_NO_READS;
  58       break;
  59     case 'a':
  60       posix_mode = O_APPEND;
  61       read_write = _IO_NO_READS|_IO_IS_APPENDING;
  62       break;
  63     default:
  64       MAYBE_SET_EINVAL;
  65       return NULL;
  66   }
  67   if (mode[0] == '+' || (mode[0] == 'b' && mode[1] == '+'))
  68     read_write &= _IO_IS_APPENDING;
  69 #ifdef F_GETFL
  70   fd_flags = _IO_fcntl (fd, F_GETFL);
  71 #ifndef O_ACCMODE
  72 #define O_ACCMODE (O_RDONLY|O_WRONLY|O_RDWR)
  73 #endif
  74   if (fd_flags == -1
  75       || ((fd_flags & O_ACCMODE) == O_RDONLY && !(read_write & _IO_NO_WRITES))
  76       || ((fd_flags & O_ACCMODE) == O_WRONLY && !(read_write & _IO_NO_READS)))
  77     return NULL;
  78
  79   /* The May 93 draft of P1003.4/D14.1 (redesignated as 1003.1b)
  80      [System Application Program Interface (API) Amendment 1:
  81      Realtime Extensions], Rationale B.8.3.3
  82      Open a Stream on a File Descriptor says:
  83
  84          Although not explicitly required by POSIX.1, a good
  85          implementation of append ("a") mode would cause the
  86          O_APPEND flag to be set.
  87
  88      (Historical implementations [such as Solaris2] do a one-time
  89      seek in fdopen.)
  90
  91      However, we do not turn O_APPEND off if the mode is "w" (even
  92      though that would seem consistent) because that would be more
  93      likely to break historical programs.
  94      */
  95   if ((posix_mode & O_APPEND) && !(fd_flags & O_APPEND))
  96     {
  97 #ifdef F_SETFL
  98       if (_IO_fcntl (fd, F_SETFL, fd_flags | O_APPEND) == -1)
  99 #endif
 100         return NULL;
 101     }
 102 #endif
 103
 104   new_f = (struct locked_FILE *) malloc (sizeof (struct locked_FILE));
 105   if (new_f == NULL)
 106     return NULL;
 107 #ifdef _IO_MTSAFE_IO
 108   new_f->fp.file._lock = &new_f->lock;
 109 #endif
 110   _IO_init (&new_f->fp.file, 0);
 111   _IO_JUMPS (&new_f->fp.file) = &_IO_file_jumps;
 112   _IO_file_init (&new_f->fp.file);
 113 #if  !_IO_UNIFIED_JUMPTABLES
 114   new_f->fp.vtable = NULL;
 115 #endif
 116   if (_IO_file_attach (&new_f->fp.file, fd) == NULL)
 117     {
 118       _IO_un_link (&new_f->fp.file);
 119       free (new_f);
 120       return NULL;
 121     }
 122   new_f->fp.file._flags &= ~_IO_DELETE_DONT_CLOSE;
 123
 124   new_f->fp.file._IO_file_flags =
 125     _IO_mask_flags (&new_f->fp.file, read_write,
 126                     _IO_NO_READS+_IO_NO_WRITES+_IO_IS_APPENDING);
 127
 128   return (_IO_FILE *) &new_f->fp;
 129 }
 130
 131 weak_alias (_IO_fdopen, fdopen)