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authorRoland McGrath <roland@gnu.org>2002-08-02 01:27:53 +0000
committerRoland McGrath <roland@gnu.org>2002-08-02 01:27:53 +0000
commite42637b67781ed47a1581c6062421de514560cb3 (patch)
tree357b08520e6b39410be8266299d4657a98c10dad /libio/iofopen.c
parent0950889b810736fe7ad340a13a5ecf76672e1a84 (diff)
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2002-07-31 Roland McGrath <roland@frob.com>
* libio/fileops.c (decide_maybe_mmap): New static function. Code taken from libio/iofopen.c:__fopen_maybe_mmap to try to mmap the file contents. Then switch the jump tables to the mmap tables if it worked, or the vanilla file tables if not. (_IO_file_underflow_maybe_mmap): New function. (_IO_file_seekoff_maybe_mmap): New function. (_IO_file_xsgetn_maybe_mmap): New function. (_IO_file_jumps_maybe_mmap): New variable, jump table using those. * libio/libioP.h: Declare those. * libio/wfileops.c (_IO_wfile_underflow_maybe_mmap): New function. (_IO_wfile_jumps_maybe_mmap): New variable, jump table using that. * libio/iofopen.c (__fopen_maybe_mmap): Don't try to mmap here. If the stream is read-only, set its jump tables to those new ones. * libio/iofdopen.c (_IO_new_fdopen) [_G_HAVE_MMAP]: Set the initial jump tables to the maybe_mmap ones, and don't call __fopen_maybe_mmap. We need the tables set before _IO_file_attach.
Diffstat (limited to 'libio/iofopen.c')
-rw-r--r--libio/iofopen.c54
1 files changed, 10 insertions, 44 deletions
diff --git a/libio/iofopen.c b/libio/iofopen.c
index c1681a4a10..00a2c5f073 100644
--- a/libio/iofopen.c
+++ b/libio/iofopen.c
@@ -43,50 +43,16 @@ __fopen_maybe_mmap (fp)
#ifdef _G_HAVE_MMAP
if (fp->_flags & _IO_NO_WRITES)
{
- /* We use the file in read-only mode. This could mean we can
- mmap the file and use it without any copying. But not all
- file descriptors are for mmap-able objects and on 32-bit
- machines we don't want to map files which are too large since
- this would require too much virtual memory. */
- struct _G_stat64 st;
-
- if (_IO_SYSSTAT (fp, &st) == 0
- && S_ISREG (st.st_mode) && st.st_size != 0
- /* Limit the file size to 1MB for 32-bit machines. */
- && (sizeof (ptrdiff_t) > 4 || st.st_size < 1*1024*1024)
- /* Sanity check. */
- && (fp->_offset == _IO_pos_BAD || fp->_offset <= st.st_size))
- {
- /* Try to map the file. */
- void *p;
-
-# ifdef _G_MMAP64
- p = _G_MMAP64 (NULL, st.st_size, PROT_READ, MAP_PRIVATE,
- fp->_fileno, 0);
-# else
- p = __mmap (NULL, st.st_size, PROT_READ, MAP_PRIVATE,
- fp->_fileno, 0);
-# endif
- if (p != MAP_FAILED)
- {
- /* OK, we managed to map the file. Set the buffer up
- and use a special jump table with simplified
- underflow functions which never tries to read
- anything from the file. */
- INTUSE(_IO_setb) (fp, p, (char *) p + st.st_size, 0);
-
- if (fp->_offset == _IO_pos_BAD)
- fp->_offset = 0;
-
- _IO_setg (fp, p, p + fp->_offset, p + fp->_offset);
-
- if (fp->_mode <= 0)
- _IO_JUMPS ((struct _IO_FILE_plus *) fp) = &_IO_file_jumps_mmap;
- else
- _IO_JUMPS ((struct _IO_FILE_plus *) fp) = &_IO_wfile_jumps_mmap;
- fp->_wide_data->_wide_vtable = &_IO_wfile_jumps_mmap;
- }
- }
+ /* Since this is read-only, we might be able to mmap the contents
+ directly. We delay the decision until the first read attempt by
+ giving it a jump table containing functions that choose mmap or
+ vanilla file operations and reset the jump table accordingly. */
+
+ if (fp->_mode <= 0)
+ _IO_JUMPS ((struct _IO_FILE_plus *) fp) = &_IO_file_jumps_maybe_mmap;
+ else
+ _IO_JUMPS ((struct _IO_FILE_plus *) fp) = &_IO_wfile_jumps_maybe_mmap;
+ fp->_wide_data->_wide_vtable = &_IO_wfile_jumps_maybe_mmap;
}
#endif
return fp;