libio/oldiofdopen.c

   1 /* Copyright (C) 1993-2023 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    <https://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 FILE *
  36 attribute_compat_text_section
  37 _IO_old_fdopen (int fd, const char *mode)
  38 {
  39   int read_write;
  40   int posix_mode = 0;
  41   struct locked_FILE
  42   {
  43     struct _IO_FILE_complete_plus fp;
  44 #ifdef _IO_MTSAFE_IO
  45     _IO_lock_t lock;
  46 #endif
  47   } *new_f;
  48   int fd_flags;
  49
  50   switch (*mode++)
  51     {
  52     case 'r':
  53       read_write = _IO_NO_WRITES;
  54       break;
  55     case 'w':
  56       read_write = _IO_NO_READS;
  57       break;
  58     case 'a':
  59       posix_mode = O_APPEND;
  60       read_write = _IO_NO_READS|_IO_IS_APPENDING;
  61       break;
  62     default:
  63       __set_errno (EINVAL);
  64       return NULL;
  65   }
  66   if (mode[0] == '+' || (mode[0] == 'b' && mode[1] == '+'))
  67     read_write &= _IO_IS_APPENDING;
  68   fd_flags = __fcntl (fd, F_GETFL);
  69   if (fd_flags == -1
  70       || ((fd_flags & O_ACCMODE) == O_RDONLY && !(read_write & _IO_NO_WRITES))
  71       || ((fd_flags & O_ACCMODE) == O_WRONLY && !(read_write & _IO_NO_READS)))
  72     return NULL;
  73
  74   /* The May 93 draft of P1003.4/D14.1 (redesignated as 1003.1b)
  75      [System Application Program Interface (API) Amendment 1:
  76      Realtime Extensions], Rationale B.8.3.3
  77      Open a Stream on a File Descriptor says:
  78
  79          Although not explicitly required by POSIX.1, a good
  80          implementation of append ("a") mode would cause the
  81          O_APPEND flag to be set.
  82
  83      (Historical implementations [such as Solaris2] do a one-time
  84      seek in fdopen.)
  85
  86      However, we do not turn O_APPEND off if the mode is "w" (even
  87      though that would seem consistent) because that would be more
  88      likely to break historical programs.
  89      */
  90   if ((posix_mode & O_APPEND) && !(fd_flags & O_APPEND))
  91     {
  92       if (__fcntl (fd, F_SETFL, fd_flags | O_APPEND) == -1)
  93         return NULL;
  94     }
  95
  96   new_f = (struct locked_FILE *) malloc (sizeof (struct locked_FILE));
  97   if (new_f == NULL)
  98     return NULL;
  99 #ifdef _IO_MTSAFE_IO
 100   new_f->fp.file._file._lock = &new_f->lock;
 101 #endif
 102   _IO_old_init (&new_f->fp.file._file, 0);
 103   _IO_JUMPS_FILE_plus (&new_f->fp) = &_IO_old_file_jumps;
 104   _IO_old_file_init_internal ((struct _IO_FILE_plus *) &new_f->fp);
 105   if (_IO_old_file_attach (&new_f->fp.file._file, fd) == NULL)
 106     {
 107       _IO_un_link ((struct _IO_FILE_plus *) &new_f->fp);
 108       free (new_f);
 109       return NULL;
 110     }
 111   new_f->fp.file._file._flags &= ~_IO_DELETE_DONT_CLOSE;
 112
 113   _IO_mask_flags (&new_f->fp.file._file, read_write,
 114                   _IO_NO_READS+_IO_NO_WRITES+_IO_IS_APPENDING);
 115
 116   return (FILE *) &new_f->fp;
 117 }
 118
 119 strong_alias (_IO_old_fdopen, __old_fdopen)
 120 compat_symbol (libc, _IO_old_fdopen, _IO_fdopen, GLIBC_2_0);
 121 compat_symbol (libc, __old_fdopen, fdopen, GLIBC_2_0);
 122
 123 #endif