libio/iofopen.c

   1 /* Copyright (C) 1993-2022 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 "libioP.h"
  28 #include <fcntl.h>
  29 #include <stdlib.h>
  30 #include <stddef.h>
  31 #include <shlib-compat.h>
  32
  33 FILE *
  34 __fopen_maybe_mmap (FILE *fp)
  35 {
  36 #if _G_HAVE_MMAP
  37   if ((fp->_flags2 & _IO_FLAGS2_MMAP) && (fp->_flags & _IO_NO_WRITES))
  38     {
  39       /* Since this is read-only, we might be able to mmap the contents
  40          directly.  We delay the decision until the first read attempt by
  41          giving it a jump table containing functions that choose mmap or
  42          vanilla file operations and reset the jump table accordingly.  */
  43
  44       if (fp->_mode <= 0)
  45         _IO_JUMPS_FILE_plus (fp) = &_IO_file_jumps_maybe_mmap;
  46       else
  47         _IO_JUMPS_FILE_plus (fp) = &_IO_wfile_jumps_maybe_mmap;
  48       fp->_wide_data->_wide_vtable = &_IO_wfile_jumps_maybe_mmap;
  49     }
  50 #endif
  51   return fp;
  52 }
  53
  54
  55 FILE *
  56 __fopen_internal (const char *filename, const char *mode, int is32)
  57 {
  58   struct locked_FILE
  59   {
  60     struct _IO_FILE_plus fp;
  61 #ifdef _IO_MTSAFE_IO
  62     _IO_lock_t lock;
  63 #endif
  64     struct _IO_wide_data wd;
  65   } *new_f = (struct locked_FILE *) malloc (sizeof (struct locked_FILE));
  66
  67   if (new_f == NULL)
  68     return NULL;
  69 #ifdef _IO_MTSAFE_IO
  70   new_f->fp.file._lock = &new_f->lock;
  71 #endif
  72   _IO_no_init (&new_f->fp.file, 0, 0, &new_f->wd, &_IO_wfile_jumps);
  73   _IO_JUMPS (&new_f->fp) = &_IO_file_jumps;
  74   _IO_new_file_init_internal (&new_f->fp);
  75   if (_IO_file_fopen ((FILE *) new_f, filename, mode, is32) != NULL)
  76     return __fopen_maybe_mmap (&new_f->fp.file);
  77
  78   _IO_un_link (&new_f->fp);
  79   free (new_f);
  80   return NULL;
  81 }
  82
  83 FILE *
  84 _IO_new_fopen (const char *filename, const char *mode)
  85 {
  86   return __fopen_internal (filename, mode, 1);
  87 }
  88
  89 strong_alias (_IO_new_fopen, __new_fopen)
  90 versioned_symbol (libc, _IO_new_fopen, _IO_fopen, GLIBC_2_1);
  91 versioned_symbol (libc, __new_fopen, fopen, GLIBC_2_1);
  92
  93 # if !defined O_LARGEFILE || O_LARGEFILE == 0
  94 weak_alias (_IO_new_fopen, _IO_fopen64)
  95 weak_alias (_IO_new_fopen, fopen64)
  96 # endif