libio/oldstdfiles.c

   1 /* Copyright (C) 1993-2021 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 /* This file provides legacy definitions of _IO_stdin_, _IO_stdout_,
  31    and _IO_stderr_.  See stdfiles.c for the current definitions.  */
  32
  33 #define _IO_USE_OLD_IO_FILE
  34 #include "libioP.h"
  35
  36 #ifdef _IO_MTSAFE_IO
  37 #define DEF_STDFILE(NAME, FD, CHAIN, FLAGS) \
  38   static _IO_lock_t _IO_stdfile_##FD##_lock = _IO_lock_initializer; \
  39   struct _IO_FILE_plus NAME \
  40     = {FILEBUF_LITERAL(CHAIN, FLAGS, FD, NULL), &_IO_old_file_jumps};
  41 #else
  42 #define DEF_STDFILE(NAME, FD, CHAIN, FLAGS) \
  43   struct _IO_FILE_plus NAME \
  44     = {FILEBUF_LITERAL(CHAIN, FLAGS, FD, NULL), &_IO_old_file_jumps};
  45 #endif
  46
  47 DEF_STDFILE(_IO_stdin_, 0, 0, _IO_NO_WRITES);
  48 DEF_STDFILE(_IO_stdout_, 1, &_IO_stdin_, _IO_NO_READS);
  49 DEF_STDFILE(_IO_stderr_, 2, &_IO_stdout_, _IO_NO_READS+_IO_UNBUFFERED);
  50
  51 #if defined __GNUC__ && __GNUC__ >= 2
  52
  53 #include <stdio.h>
  54
  55 extern const int _IO_stdin_used;
  56 weak_extern (_IO_stdin_used);
  57
  58 #undef stdin
  59 #undef stdout
  60 #undef stderr
  61
  62 extern FILE *stdin;
  63 extern FILE *stdout;
  64 extern FILE *stderr;
  65
  66 static void _IO_check_libio (void) __THROW __attribute__ ((constructor));
  67
  68 /* This function determines which shared C library the application
  69    was linked against. We then set up the stdin/stdout/stderr and
  70    _IO_list_all accordingly. */
  71
  72 static void
  73 _IO_check_libio (void)
  74 {
  75   if (&_IO_stdin_used == NULL)
  76     {
  77       /* We are using the old one. */
  78       stdin = (FILE *) &_IO_stdin_;
  79       stdout = (FILE *) &_IO_stdout_;
  80       stderr = (FILE *) &_IO_stderr_;
  81       _IO_list_all = &_IO_stderr_;
  82       stdin->_vtable_offset = stdout->_vtable_offset
  83         = stderr->_vtable_offset =
  84         ((int) sizeof (struct _IO_FILE)
  85          - (int) sizeof (struct _IO_FILE_complete));
  86
  87       if (_IO_stdin_.vtable != &_IO_old_file_jumps
  88           || _IO_stdout_.vtable != &_IO_old_file_jumps
  89           || _IO_stderr_.vtable != &_IO_old_file_jumps)
  90         IO_set_accept_foreign_vtables (&_IO_vtable_check);
  91     }
  92 }
  93
  94 #endif
  95
  96 #endif