libio/iofopen.c

   1 /* Copyright (C) 1993,1997,1998,1999,2000,2002 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, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.
  18
  19    As a special exception, if you link the code in this file with
  20    files compiled with a GNU compiler to produce an executable,
  21    that does not cause the resulting executable to be covered by
  22    the GNU Lesser General Public License.  This exception does not
  23    however invalidate any other reasons why the executable file
  24    might be covered by the GNU Lesser General Public License.
  25    This exception applies to code released by its copyright holders
  26    in files containing the exception.  */
  27
  28 #include "libioP.h"
  29 #ifdef __STDC__
  30 #include <stdlib.h>
  31 #include <stddef.h>
  32 #endif
  33 #ifdef _LIBC
  34 # include <shlib-compat.h>
  35 #else
  36 # define _IO_new_fopen fopen
  37 #endif
  38
  39 _IO_FILE *
  40 __fopen_maybe_mmap (fp)
  41      _IO_FILE *fp;
  42 {
  43 #ifdef _G_HAVE_MMAP
  44   if (fp->_flags & _IO_NO_WRITES)
  45     {
  46       /* We use the file in read-only mode.  This could mean we can
  47          mmap the file and use it without any copying.  But not all
  48          file descriptors are for mmap-able objects and on 32-bit
  49          machines we don't want to map files which are too large since
  50          this would require too much virtual memory.  */
  51       struct _G_stat64 st;
  52
  53       if (_IO_SYSSTAT (fp, &st) == 0
  54           && S_ISREG (st.st_mode) && st.st_size != 0
  55           /* Limit the file size to 1MB for 32-bit machines.  */
  56           && (sizeof (ptrdiff_t) > 4 || st.st_size < 1*1024*1024)
  57           /* Sanity check.  */
  58           && (fp->_offset == _IO_pos_BAD || fp->_offset <= st.st_size))
  59         {
  60           /* Try to map the file.  */
  61           void *p;
  62
  63 # ifdef _G_MMAP64
  64           p = _G_MMAP64 (NULL, st.st_size, PROT_READ, MAP_PRIVATE,
  65                          fp->_fileno, 0);
  66 # else
  67           p = __mmap (NULL, st.st_size, PROT_READ, MAP_PRIVATE,
  68                       fp->_fileno, 0);
  69 # endif
  70           if (p != MAP_FAILED)
  71             {
  72               /* OK, we managed to map the file.  Set the buffer up
  73                  and use a special jump table with simplified
  74                  underflow functions which never tries to read
  75                  anything from the file.  */
  76               INTUSE(_IO_setb) (fp, p, (char *) p + st.st_size, 0);
  77
  78               if (fp->_offset == _IO_pos_BAD)
  79                 fp->_offset = 0;
  80
  81               _IO_setg (fp,  p, p + fp->_offset, p + fp->_offset);
  82
  83               if (fp->_mode <= 0)
  84                 _IO_JUMPS ((struct _IO_FILE_plus *) fp) = &_IO_file_jumps_mmap;
  85               else
  86                 _IO_JUMPS ((struct _IO_FILE_plus *) fp) = &_IO_wfile_jumps_mmap;
  87               fp->_wide_data->_wide_vtable = &_IO_wfile_jumps_mmap;
  88             }
  89         }
  90     }
  91 #endif
  92   return fp;
  93 }
  94
  95
  96 _IO_FILE *
  97 __fopen_internal (filename, mode, is32)
  98      const char *filename;
  99      const char *mode;
 100      int is32;
 101 {
 102   struct locked_FILE
 103   {
 104     struct _IO_FILE_plus fp;
 105 #ifdef _IO_MTSAFE_IO
 106     _IO_lock_t lock;
 107 #endif
 108     struct _IO_wide_data wd;
 109   } *new_f = (struct locked_FILE *) malloc (sizeof (struct locked_FILE));
 110
 111   if (new_f == NULL)
 112     return NULL;
 113 #ifdef _IO_MTSAFE_IO
 114   new_f->fp.file._lock = &new_f->lock;
 115 #endif
 116 #if defined _LIBC || defined _GLIBCPP_USE_WCHAR_T
 117   _IO_no_init (&new_f->fp.file, 0, 0, &new_f->wd, &INTUSE(_IO_wfile_jumps));
 118 #else
 119   _IO_no_init (&new_f->fp.file, 1, 0, NULL, NULL);
 120 #endif
 121   _IO_JUMPS (&new_f->fp) = &INTUSE(_IO_file_jumps);
 122   INTUSE(_IO_file_init) (&new_f->fp);
 123 #if  !_IO_UNIFIED_JUMPTABLES
 124   new_f->fp.vtable = NULL;
 125 #endif
 126   if (INTUSE(_IO_file_fopen) ((_IO_FILE *) new_f, filename, mode, is32)
 127       != NULL)
 128     return __fopen_maybe_mmap (&new_f->fp.file);
 129
 130   INTUSE(_IO_un_link) (&new_f->fp);
 131   free (new_f);
 132   return NULL;
 133 }
 134
 135 _IO_FILE *
 136 _IO_new_fopen (filename, mode)
 137      const char *filename;
 138      const char *mode;
 139 {
 140   return __fopen_internal (filename, mode, 1);
 141 }
 142
 143 #ifdef _LIBC
 144 strong_alias (_IO_new_fopen, __new_fopen)
 145 versioned_symbol (libc, _IO_new_fopen, _IO_fopen, GLIBC_2_1);
 146 versioned_symbol (libc, __new_fopen, fopen, GLIBC_2_1);
 147 #endif