libio/oldiofdopen.c

   1 /* Copyright (C) 1993-2016 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.
  17
  18    As a special exception, if you link the code in this file with
  19    files compiled with a GNU compiler to produce an executable,
  20    that does not cause the resulting executable to be covered by
  21    the GNU Lesser General Public License.  This exception does not
  22    however invalidate any other reasons why the executable file
  23    might be covered by the GNU Lesser General Public License.
  24    This exception applies to code released by its copyright holders
  25    in files containing the exception.  */
  26
  27 #include <shlib-compat.h>
  28 #if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1)
  29
  30 #define _IO_USE_OLD_IO_FILE
  31 #include <stdlib.h>
  32 #include "libioP.h"
  33 #include <fcntl.h>
  34
  35 #ifndef _IO_fcntl
  36 # define _IO_fcntl __fcntl
  37 #endif
  38
  39 _IO_FILE *
  40 attribute_compat_text_section
  41 _IO_old_fdopen (int fd, const char *mode)
  42 {
  43   int read_write;
  44   int posix_mode = 0;
  45   struct locked_FILE
  46   {
  47     struct _IO_FILE_complete_plus fp;
  48 #ifdef _IO_MTSAFE_IO
  49     _IO_lock_t lock;
  50 #endif
  51   } *new_f;
  52   int fd_flags;
  53
  54   switch (*mode++)
  55     {
  56     case 'r':
  57       read_write = _IO_NO_WRITES;
  58       break;
  59     case 'w':
  60       read_write = _IO_NO_READS;
  61       break;
  62     case 'a':
  63       posix_mode = O_APPEND;
  64       read_write = _IO_NO_READS|_IO_IS_APPENDING;
  65       break;
  66     default:
  67       MAYBE_SET_EINVAL;
  68       return NULL;
  69   }
  70   if (mode[0] == '+' || (mode[0] == 'b' && mode[1] == '+'))
  71     read_write &= _IO_IS_APPENDING;
  72 #ifdef F_GETFL
  73   fd_flags = _IO_fcntl (fd, F_GETFL);
  74 #ifndef O_ACCMODE
  75 #define O_ACCMODE (O_RDONLY|O_WRONLY|O_RDWR)
  76 #endif
  77   if (fd_flags == -1
  78       || ((fd_flags & O_ACCMODE) == O_RDONLY && !(read_write & _IO_NO_WRITES))
  79       || ((fd_flags & O_ACCMODE) == O_WRONLY && !(read_write & _IO_NO_READS)))
  80     return NULL;
  81
  82   /* The May 93 draft of P1003.4/D14.1 (redesignated as 1003.1b)
  83      [System Application Program Interface (API) Amendment 1:
  84      Realtime Extensions], Rationale B.8.3.3
  85      Open a Stream on a File Descriptor says:
  86
  87          Although not explicitly required by POSIX.1, a good
  88          implementation of append ("a") mode would cause the
  89          O_APPEND flag to be set.
  90
  91      (Historical implementations [such as Solaris2] do a one-time
  92      seek in fdopen.)
  93
  94      However, we do not turn O_APPEND off if the mode is "w" (even
  95      though that would seem consistent) because that would be more
  96      likely to break historical programs.
  97      */
  98   if ((posix_mode & O_APPEND) && !(fd_flags & O_APPEND))
  99     {
 100 #ifdef F_SETFL
 101       if (_IO_fcntl (fd, F_SETFL, fd_flags | O_APPEND) == -1)
 102 #endif
 103         return NULL;
 104     }
 105 #endif
 106
 107   new_f = (struct locked_FILE *) malloc (sizeof (struct locked_FILE));
 108   if (new_f == NULL)
 109     return NULL;
 110 #ifdef _IO_MTSAFE_IO
 111   new_f->fp.file._file._lock = &new_f->lock;
 112 #endif
 113   _IO_old_init (&new_f->fp.file._file, 0);
 114   _IO_JUMPS_FILE_plus (&new_f->fp) = &_IO_old_file_jumps;
 115   _IO_old_file_init ((struct _IO_FILE_plus *) &new_f->fp);
 116 #if  !_IO_UNIFIED_JUMPTABLES
 117   new_f->fp.vtable = NULL;
 118 #endif
 119   if (_IO_old_file_attach (&new_f->fp.file._file, fd) == NULL)
 120     {
 121       _IO_un_link ((struct _IO_FILE_plus *) &new_f->fp);
 122       free (new_f);
 123       return NULL;
 124     }
 125   new_f->fp.file._file._flags &= ~_IO_DELETE_DONT_CLOSE;
 126
 127   _IO_mask_flags (&new_f->fp.file._file, read_write,
 128                   _IO_NO_READS+_IO_NO_WRITES+_IO_IS_APPENDING);
 129
 130   return (_IO_FILE *) &new_f->fp;
 131 }
 132
 133 strong_alias (_IO_old_fdopen, __old_fdopen)
 134 compat_symbol (libc, _IO_old_fdopen, _IO_fdopen, GLIBC_2_0);
 135 compat_symbol (libc, __old_fdopen, fdopen, GLIBC_2_0);
 136
 137 #endif