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 #ifdef EINVAL
  65       errno = EINVAL;
  66 #endif
  67       return NULL;
  68   }
  69   if (mode[0] == '+' || (mode[0] == 'b' && mode[1] == '+'))
  70     read_write &= _IO_IS_APPENDING;
  71 #ifdef F_GETFL
  72   fd_flags = _IO_fcntl (fd, F_GETFL);
  73 #ifndef O_ACCMODE
  74 #define O_ACCMODE (O_RDONLY|O_WRONLY|O_RDWR)
  75 #endif
  76   if (fd_flags == -1
  77       || ((fd_flags & O_ACCMODE) == O_RDONLY && !(read_write & _IO_NO_WRITES))
  78       || ((fd_flags & O_ACCMODE) == O_WRONLY && !(read_write & _IO_NO_READS)))
  79     return NULL;
  80
  81   /* The May 93 draft of P1003.4/D14.1 (redesignated as 1003.1b)
  82      [System Application Program Interface (API) Amendment 1:
  83      Realtime Extensions], Rationale B.8.3.3
  84      Open a Stream on a File Descriptor says:
  85
  86          Although not explicitly required by POSIX.1, a good
  87          implementation of append ("a") mode would cause the
  88          O_APPEND flag to be set.
  89
  90      (Historical implementations [such as Solaris2] do a one-time
  91      seek in fdopen.)
  92
  93      However, we do not turn O_APPEND off if the mode is "w" (even
  94      though that would seem consistent) because that would be more
  95      likely to break historical programs.
  96      */
  97   if ((posix_mode & O_APPEND) && !(fd_flags & O_APPEND))
  98     {
  99 #ifdef F_SETFL
 100       if (_IO_fcntl (fd, F_SETFL, fd_flags | O_APPEND) == -1)
 101 #endif
 102         return NULL;
 103     }
 104 #endif
 105
 106   new_f = (struct locked_FILE *) malloc (sizeof (struct locked_FILE));
 107   if (new_f == NULL)
 108     return NULL;
 109 #ifdef _IO_MTSAFE_IO
 110   new_f->fp.file._lock = &new_f->lock;
 111 #endif
 112   _IO_init (&new_f->fp.file, 0);
 113   _IO_JUMPS (&new_f->fp.file) = &_IO_file_jumps;
 114   _IO_file_init (&new_f->fp.file);
 115 #if  !_IO_UNIFIED_JUMPTABLES
 116   new_f->fp.vtable = NULL;
 117 #endif
 118   if (_IO_file_attach (&new_f->fp.file, fd) == NULL)
 119     {
 120       _IO_un_link (&new_f->fp.file);
 121       free (new_f);
 122       return NULL;
 123     }
 124   new_f->fp.file._flags &= ~_IO_DELETE_DONT_CLOSE;
 125
 126   new_f->fp.file._IO_file_flags =
 127     _IO_mask_flags (&new_f->fp.file, read_write,
 128                     _IO_NO_READS+_IO_NO_WRITES+_IO_IS_APPENDING);
 129
 130   return (_IO_FILE *) &new_f->fp;
 131 }
 132
 133 weak_alias (_IO_fdopen, fdopen)