libio/iofdopen.c

   1 /* Copyright (C) 1993, 1994, 1997, 1998 Free Software Foundation, Inc.
   2    This file is part of the GNU IO Library.
   3
   4    This library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU General Public License as
   6    published by the Free Software Foundation; either version 2, or (at
   7    your option) any later version.
   8
   9    This library is distributed in the hope that it will be useful, but
  10    WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this library; see the file COPYING.  If not, write to
  16    the Free Software Foundation, 59 Temple Place - Suite 330, Boston,
  17    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
  21    not cause the resulting executable to be covered by the GNU General
  22    Public License.  This exception does not however invalidate any
  23    other reasons why the executable file might be covered by the GNU
  24    General Public License.  */
  25
  26 #ifdef __STDC__
  27 #include <stdlib.h>
  28 #endif
  29 #include "libioP.h"
  30 #include <fcntl.h>
  31
  32 #ifndef _IO_fcntl
  33 #ifdef _LIBC
  34 #define _IO_fcntl __fcntl
  35 #else
  36 #define _IO_fcntl fcntl
  37 #endif
  38 #endif
  39
  40 _IO_FILE *
  41 _IO_new_fdopen (fd, mode)
  42      int fd;
  43      const char *mode;
  44 {
  45   int read_write;
  46   int posix_mode = 0;
  47   struct locked_FILE
  48   {
  49     struct _IO_FILE_plus fp;
  50 #ifdef _IO_MTSAFE_IO
  51     _IO_lock_t lock;
  52 #endif
  53   } *new_f;
  54   int fd_flags;
  55
  56   switch (*mode++)
  57     {
  58     case 'r':
  59       read_write = _IO_NO_WRITES;
  60       break;
  61     case 'w':
  62       read_write = _IO_NO_READS;
  63       break;
  64     case 'a':
  65       posix_mode = O_APPEND;
  66       read_write = _IO_NO_READS|_IO_IS_APPENDING;
  67       break;
  68     default:
  69       MAYBE_SET_EINVAL;
  70       return NULL;
  71   }
  72   if (mode[0] == '+' || (mode[0] == 'b' && mode[1] == '+'))
  73     read_write &= _IO_IS_APPENDING;
  74 #ifdef F_GETFL
  75   fd_flags = _IO_fcntl (fd, F_GETFL);
  76 #ifndef O_ACCMODE
  77 #define O_ACCMODE (O_RDONLY|O_WRONLY|O_RDWR)
  78 #endif
  79   if (fd_flags == -1
  80       || ((fd_flags & O_ACCMODE) == O_RDONLY && !(read_write & _IO_NO_WRITES))
  81       || ((fd_flags & O_ACCMODE) == O_WRONLY && !(read_write & _IO_NO_READS)))
  82     return NULL;
  83
  84   /* The May 93 draft of P1003.4/D14.1 (redesignated as 1003.1b)
  85      [System Application Program Interface (API) Amendment 1:
  86      Realtime Extensions], Rationale B.8.3.3
  87      Open a Stream on a File Descriptor says:
  88
  89          Although not explicitly required by POSIX.1, a good
  90          implementation of append ("a") mode would cause the
  91          O_APPEND flag to be set.
  92
  93      (Historical implementations [such as Solaris2] do a one-time
  94      seek in fdopen.)
  95
  96      However, we do not turn O_APPEND off if the mode is "w" (even
  97      though that would seem consistent) because that would be more
  98      likely to break historical programs.
  99      */
 100   if ((posix_mode & O_APPEND) && !(fd_flags & O_APPEND))
 101     {
 102 #ifdef F_SETFL
 103       if (_IO_fcntl (fd, F_SETFL, fd_flags | O_APPEND) == -1)
 104 #endif
 105         return NULL;
 106     }
 107 #endif
 108
 109   new_f = (struct locked_FILE *) malloc (sizeof (struct locked_FILE));
 110   if (new_f == NULL)
 111     return NULL;
 112 #ifdef _IO_MTSAFE_IO
 113   new_f->fp.file._lock = &new_f->lock;
 114 #endif
 115   _IO_init (&new_f->fp.file, 0);
 116   _IO_JUMPS (&new_f->fp) = &_IO_file_jumps;
 117   _IO_file_init (&new_f->fp.file);
 118 #if  !_IO_UNIFIED_JUMPTABLES
 119   new_f->fp.vtable = NULL;
 120 #endif
 121   if (_IO_file_attach (&new_f->fp.file, fd) == NULL)
 122     {
 123       _IO_un_link (&new_f->fp.file);
 124       free (new_f);
 125       return NULL;
 126     }
 127   new_f->fp.file._flags &= ~_IO_DELETE_DONT_CLOSE;
 128
 129   new_f->fp.file._IO_file_flags =
 130     _IO_mask_flags (&new_f->fp.file, read_write,
 131                     _IO_NO_READS+_IO_NO_WRITES+_IO_IS_APPENDING);
 132
 133   return (_IO_FILE *) &new_f->fp;
 134 }
 135
 136 #if defined PIC && DO_VERSIONING
 137 strong_alias (_IO_new_fdopen, __new_fdopen)
 138 default_symbol_version (_IO_new_fdopen, _IO_fdopen, GLIBC_2.1);
 139 default_symbol_version (__new_fdopen, fdopen, GLIBC_2.1);
 140 #else
 141 # ifdef weak_alias
 142 weak_alias (_IO_new_fdopen, _IO_fdopen)
 143 weak_alias (_IO_new_fdopen, fdopen)
 144 # endif
 145 #endif