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2002-07-31 Roland McGrath <roland@frob.com>

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* 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.
This commit is contained in:
Roland McGrath
2002-08-02 01:27:53 +00:00
parent 0950889b81
commit e42637b677
3 changed files with 28 additions and 46 deletions
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52
libio/iofopen.c
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@ -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;
/* 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 (_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;
}
}
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;