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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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17
libio/iofdopen.c
View File

@ -124,8 +124,19 @@ _IO_new_fdopen (fd, mode)
#ifdef _IO_MTSAFE_IO
new_f->fp.file._lock = &new_f->lock;
#endif
_IO_no_init (&new_f->fp.file, 0, 0, &new_f->wd, &INTUSE(_IO_wfile_jumps));
_IO_JUMPS (&new_f->fp) = &INTUSE(_IO_file_jumps);
/* Set up initially to use the `maybe_mmap' jump tables rather than using
__fopen_maybe_mmap to do it, because we need them in place before we
call _IO_file_attach or else it will allocate a buffer immediately. */
_IO_no_init (&new_f->fp.file, 0, 0, &new_f->wd,
#ifdef _G_HAVE_MMAP
(read_write & _IO_NO_WRITES) ? &_IO_wfile_jumps_maybe_mmap :
#endif
&INTUSE(_IO_wfile_jumps));
_IO_JUMPS (&new_f->fp) =
#ifdef _G_HAVE_MMAP
(read_write & _IO_NO_WRITES) ? &_IO_file_jumps_maybe_mmap :
#endif
&INTUSE(_IO_file_jumps);
INTUSE(_IO_file_init) (&new_f->fp);
#if !_IO_UNIFIED_JUMPTABLES
new_f->fp.vtable = NULL;
@ -143,7 +154,7 @@ _IO_new_fdopen (fd, mode)
_IO_mask_flags (&new_f->fp.file, read_write,
_IO_NO_READS+_IO_NO_WRITES+_IO_IS_APPENDING);
return __fopen_maybe_mmap (&new_f->fp.file);
return &new_f->fp.file;
}
INTDEF2(_IO_new_fdopen, _IO_fdopen)

52
libio/iofopen.c
View File

@ -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;

5
libio/libioP.h
View File

@ -425,8 +425,10 @@ extern void _IO_default_imbue __P ((_IO_FILE *, void *));
extern struct _IO_jump_t _IO_file_jumps;
extern struct _IO_jump_t _IO_file_jumps_mmap attribute_hidden;
extern struct _IO_jump_t _IO_file_jumps_maybe_mmap attribute_hidden;
extern struct _IO_jump_t _IO_wfile_jumps attribute_hidden;
extern struct _IO_jump_t _IO_wfile_jumps_mmap attribute_hidden;
extern struct _IO_jump_t _IO_wfile_jumps_maybe_mmap attribute_hidden;
extern struct _IO_jump_t _IO_old_file_jumps attribute_hidden;
extern struct _IO_jump_t _IO_streambuf_jumps;
extern struct _IO_jump_t _IO_proc_jumps attribute_hidden;
@ -498,6 +500,8 @@ extern _IO_FILE* _IO_file_setbuf __P ((_IO_FILE *, char *, _IO_ssize_t));
extern _IO_off64_t _IO_file_seekoff __P ((_IO_FILE *, _IO_off64_t, int, int));
extern _IO_off64_t _IO_file_seekoff_mmap __P ((_IO_FILE *, _IO_off64_t, int,
int));
extern _IO_off64_t _IO_file_seekoff_maybe_mmap __P ((_IO_FILE *, _IO_off64_t,
int, int));
extern _IO_size_t _IO_file_xsputn __P ((_IO_FILE *, const void *, _IO_size_t));
extern _IO_size_t _IO_file_xsgetn __P ((_IO_FILE *, void *, _IO_size_t));
extern int _IO_file_stat __P ((_IO_FILE *, void *));
@ -505,6 +509,7 @@ extern int _IO_file_close __P ((_IO_FILE *));
extern int _IO_file_close_mmap __P ((_IO_FILE *));
extern int _IO_file_underflow __P ((_IO_FILE *));
extern int _IO_file_underflow_mmap __P ((_IO_FILE *));
extern int _IO_file_underflow_maybe_mmap __P ((_IO_FILE *));
extern int _IO_file_overflow __P ((_IO_FILE *, int));
#define _IO_file_is_open(__fp) ((__fp)->_fileno != -1)
extern void _IO_file_init __P ((struct _IO_FILE_plus *));