lib/glibc
1
0
Fork 0
mirror of https://sourceware.org/git/glibc.git synced 2025-07-29 11:41:21 +03:00
Code Activity

* libio/fileops.c (_IO_file_sync_mmap): New function.

Browse Source 
(_IO_file_jumps_mmap): Use it.
	(_IO_file_underflow_mmap): Rewritten.  If after EOF or fflush,
	repeat the stat check and resize the mapped buffer as necessary.

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.

	* libio/tst-mmap-eofsync.c: New file.
	* libio/tst-mmap-fflushsync.c: New file.
	* libio/bug-mmap-fflush.c: New file.
	* libio/tst-mmap2-eofsync.c: New file.
	* libio/Makefile (tests): Add them.

	* libio/wfileops.c (_IO_wfile_underflow_mmap): Don't set EOF bit when
	_IO_file_underflow_mmap fails, it already set the appropriate bit.
This commit is contained in:
Roland McGrath
2002-08-02 01:29:37 +00:00
parent e42637b677
commit acbee5f637
8 changed files with 724 additions and 32 deletions
Download Patch File Download Diff File Expand all files Collapse all files

304
libio/fileops.c
View File

@ -601,42 +601,207 @@ _IO_new_file_underflow (fp)
}
INTDEF2(_IO_new_file_underflow, _IO_file_underflow)
/* Special callback replacing the underflow callbacks if we mmap the
file. */
int
_IO_file_underflow_mmap (_IO_FILE *fp)
/* Guts of underflow callback if we mmap the file. This stats the file and
updates the stream state to match. In the normal case we return zero.
If the file is no longer eligible for mmap, its jump tables are reset to
the vanilla ones and we return nonzero. */
static int
mmap_remap_check (_IO_FILE *fp)
{
if (fp->_IO_read_end < fp->_IO_buf_end)
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))
{
/* A stupid requirement in POSIX says that the first read on a
stream must update the atime. Just read a single byte. We
don't have to worry about repositioning the file descriptor
since the following seek defines its position anyway. */
char ignore[1];
read (fp->_fileno, ignore, 1);
const size_t pagesize = __getpagesize ();
# define ROUNDED(x) (((x) + pagesize - 1) & ~(pagesize - 1))
if (ROUNDED (st.st_size) < ROUNDED (fp->_IO_buf_end
- fp->_IO_buf_base))
{
/* We can trim off some pages past the end of the file. */
(void) __munmap (fp->_IO_buf_base + ROUNDED (st.st_size),
ROUNDED (fp->_IO_buf_end - fp->_IO_buf_base)
- ROUNDED (st.st_size));
fp->_IO_buf_end = fp->_IO_buf_base + st.st_size;
}
else if (ROUNDED (st.st_size) > ROUNDED (fp->_IO_buf_end
- fp->_IO_buf_base))
{
/* The file added some pages. We need to remap it. */
void *p;
#if defined __linux__ /* XXX */
p = __mremap (fp->_IO_buf_base, ROUNDED (fp->_IO_buf_end
- fp->_IO_buf_base),
ROUNDED (st.st_size), MREMAP_MAYMOVE);
if (p == MAP_FAILED)
{
(void) __munmap (fp->_IO_buf_base,
fp->_IO_buf_end - fp->_IO_buf_base);
goto punt;
}
#else
(void) __munmap (fp->_IO_buf_base,
fp->_IO_buf_end - fp->_IO_buf_base);
# ifdef _G_MMAP64
p = _G_MMAP64 (NULL, st.st_size, PROT_READ, MAP_SHARED,
fp->_fileno, 0);
# else
p = __mmap (NULL, st.st_size, PROT_READ, MAP_SHARED,
fp->_fileno, 0);
# endif
if (p == MAP_FAILED)
goto punt;
#endif
fp->_IO_buf_base = p;
fp->_IO_buf_end = fp->_IO_buf_base + st.st_size;
}
else
{
/* The number of pages didn't change. */
fp->_IO_buf_end = fp->_IO_buf_base + st.st_size;
}
# undef ROUNDED
fp->_offset -= fp->_IO_read_end - fp->_IO_read_ptr;
_IO_setg (fp, fp->_IO_buf_base, fp->_IO_buf_base + fp->_offset,
fp->_IO_buf_end);
if (
# ifdef _G_LSEEK64
_G_LSEEK64 (fp->_fileno, fp->_IO_buf_end - fp->_IO_buf_base,
SEEK_SET)
_G_LSEEK64
# else
__lseek (fp->_fileno, fp->_IO_buf_end - fp->_IO_buf_base, SEEK_SET)
__lseek
# endif
(fp->_fileno, fp->_IO_buf_end - fp->_IO_buf_base, SEEK_SET)
!= fp->_IO_buf_end - fp->_IO_buf_base)
{
fp->_flags |= _IO_ERR_SEEN;
return EOF;
}
fp->_offset = fp->_IO_buf_end - fp->_IO_buf_base;
fp->_IO_read_end = fp->_IO_buf_end;
return *(unsigned char *) fp->_IO_read_ptr;
return 0;
}
else
{
/* Life is no longer good for mmap. Punt it. */
(void) __munmap (fp->_IO_buf_base,
fp->_IO_buf_end - fp->_IO_buf_base);
punt:
fp->_IO_buf_base = fp->_IO_buf_end = NULL;
_IO_setg (fp, NULL, NULL, NULL);
if (fp->_mode <= 0)
_IO_JUMPS ((struct _IO_FILE_plus *) fp) = &_IO_file_jumps;
else
_IO_JUMPS ((struct _IO_FILE_plus *) fp) = &_IO_wfile_jumps;
fp->_wide_data->_wide_vtable = &_IO_wfile_jumps;
return 1;
}
}
/* Special callback replacing the underflow callbacks if we mmap the file. */
int
_IO_file_underflow_mmap (_IO_FILE *fp)
{
if (fp->_IO_read_ptr < fp->_IO_read_end)
return *(unsigned char *) fp->_IO_read_ptr;
if (__builtin_expect (mmap_remap_check (fp), 0))
/* We punted to the regular file functions. */
return _IO_UNDERFLOW (fp);
if (fp->_IO_read_ptr < fp->_IO_read_end)
return *(unsigned char *) fp->_IO_read_ptr;
fp->_flags |= _IO_EOF_SEEN;
return EOF;
}
static void
decide_maybe_mmap (_IO_FILE *fp)
{
/* 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_SHARED, fp->_fileno, 0);
# else
p = __mmap (NULL, st.st_size, PROT_READ, MAP_SHARED, 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. */
if (
# ifdef _G_LSEEK64
_G_LSEEK64
# else
__lseek
# endif
(fp->_fileno, st.st_size, SEEK_SET) != st.st_size)
{
(void) __munmap (p, st.st_size);
fp->_offset = _IO_pos_BAD;
}
else
{
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 + st.st_size);
fp->_offset = st.st_size;
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;
return;
}
}
}
/* We couldn't use mmap, so revert to the vanilla file operations. */
if (fp->_mode <= 0)
_IO_JUMPS ((struct _IO_FILE_plus *) fp) = &_IO_file_jumps;
else
_IO_JUMPS ((struct _IO_FILE_plus *) fp) = &_IO_wfile_jumps;
fp->_wide_data->_wide_vtable = &_IO_wfile_jumps;
}
int
_IO_file_underflow_maybe_mmap (_IO_FILE *fp)
{
/* This is the first read attempt. Choose mmap or vanilla operations
and then punt to the chosen underflow routine. */
decide_maybe_mmap (fp);
return _IO_UNDERFLOW (fp);
}
int
_IO_new_file_overflow (f, ch)
_IO_FILE *f;
@ -726,6 +891,34 @@ _IO_new_file_sync (fp)
}
INTDEF2(_IO_new_file_sync, _IO_file_sync)
static int
_IO_file_sync_mmap (_IO_FILE *fp)
{
if (fp->_IO_read_ptr != fp->_IO_read_end)
{
#ifdef TODO
if (_IO_in_backup (fp))
delta -= eGptr () - Gbase ();
#endif
if (
# ifdef _G_LSEEK64
_G_LSEEK64
# else
__lseek
# endif
(fp->_fileno, fp->_IO_read_ptr - fp->_IO_buf_base, SEEK_SET)
!= fp->_IO_read_ptr - fp->_IO_buf_base)
{
fp->_flags |= _IO_ERR_SEEN;
return EOF;
}
}
fp->_offset = fp->_IO_read_ptr - fp->_IO_buf_base;
fp->_IO_read_end = fp->_IO_read_ptr = fp->_IO_read_base;
return 0;
}
_IO_off64_t
_IO_new_file_seekoff (fp, offset, dir, mode)
_IO_FILE *fp;
@ -968,6 +1161,25 @@ _IO_file_seekoff_mmap (fp, offset, dir, mode)
return offset;
}
_IO_off64_t
_IO_file_seekoff_maybe_mmap (fp, offset, dir, mode)
_IO_FILE *fp;
_IO_off64_t offset;
int dir;
int mode;
{
/* We only get here when we haven't tried to read anything yet.
So there is nothing more useful for us to do here than just
the underlying lseek call. */
_IO_off64_t result = _IO_SYSSEEK (fp, offset, dir);
if (result < 0)
return EOF;
fp->_offset = result;
return result;
}
_IO_ssize_t
_IO_file_read (fp, buf, size)
_IO_FILE *fp;
@ -1009,9 +1221,8 @@ int
_IO_file_close_mmap (fp)
_IO_FILE *fp;
{
/* In addition to closing the file descriptor we have to unmap the
file. */
(void) munmap (fp->_IO_buf_base, fp->_IO_buf_end - fp->_IO_buf_base);
/* In addition to closing the file descriptor we have to unmap the file. */
(void) __munmap (fp->_IO_buf_base, fp->_IO_buf_end - fp->_IO_buf_base);
fp->_IO_buf_base = fp->_IO_buf_end = NULL;
return close (fp->_fileno);
}
@ -1270,11 +1481,13 @@ _IO_file_xsgetn_mmap (fp, data, n)
if (have < n)
{
/* Maybe the read buffer is not yet fully set up. */
fp->_IO_read_ptr = fp->_IO_read_end;
if (fp->_IO_read_end < fp->_IO_buf_end
&& _IO_file_underflow_mmap (fp) != EOF)
have = fp->_IO_read_end - read_ptr;
/* Check that we are mapping all of the file, in case it grew. */
if (__builtin_expect (mmap_remap_check (fp), 0))
/* We punted mmap, so complete with the vanilla code. */
return s - (char *) data + _IO_XSGETN (fp, data, n);
read_ptr = fp->_IO_read_ptr;
have = fp->_IO_read_end - read_ptr;
}
}
@ -1296,6 +1509,21 @@ _IO_file_xsgetn_mmap (fp, data, n)
return s - (char *) data;
}
static _IO_size_t _IO_file_xsgetn_maybe_mmap __P ((_IO_FILE *, void *,
_IO_size_t));
static _IO_size_t
_IO_file_xsgetn_maybe_mmap (fp, data, n)
_IO_FILE *fp;
void *data;
_IO_size_t n;
{
/* We only get here if this is the first attempt to read something.
Decide which operations to use and then punt to the chosen one. */
decide_maybe_mmap (fp);
return _IO_XSGETN (fp, data, n);
}
struct _IO_jump_t _IO_file_jumps =
{
JUMP_INIT_DUMMY,
@ -1334,7 +1562,7 @@ struct _IO_jump_t _IO_file_jumps_mmap =
JUMP_INIT(seekoff, _IO_file_seekoff_mmap),
JUMP_INIT(seekpos, _IO_default_seekpos),
JUMP_INIT(setbuf, (_IO_setbuf_t) _IO_file_setbuf_mmap),
JUMP_INIT(sync, _IO_new_file_sync),
JUMP_INIT(sync, _IO_file_sync_mmap),
JUMP_INIT(doallocate, INTUSE(_IO_file_doallocate)),
JUMP_INIT(read, INTUSE(_IO_file_read)),
JUMP_INIT(write, _IO_new_file_write),
@ -1345,6 +1573,30 @@ struct _IO_jump_t _IO_file_jumps_mmap =
JUMP_INIT(imbue, _IO_default_imbue)
};
struct _IO_jump_t _IO_file_jumps_maybe_mmap =
{
JUMP_INIT_DUMMY,
JUMP_INIT(finish, INTUSE(_IO_file_finish)),
JUMP_INIT(overflow, INTUSE(_IO_file_overflow)),
JUMP_INIT(underflow, _IO_file_underflow_maybe_mmap),
JUMP_INIT(uflow, INTUSE(_IO_default_uflow)),
JUMP_INIT(pbackfail, INTUSE(_IO_default_pbackfail)),
JUMP_INIT(xsputn, _IO_new_file_xsputn),
JUMP_INIT(xsgetn, _IO_file_xsgetn_maybe_mmap),
JUMP_INIT(seekoff, _IO_file_seekoff_maybe_mmap),
JUMP_INIT(seekpos, _IO_default_seekpos),
JUMP_INIT(setbuf, (_IO_setbuf_t) _IO_file_setbuf_mmap),
JUMP_INIT(sync, _IO_new_file_sync),
JUMP_INIT(doallocate, INTUSE(_IO_file_doallocate)),
JUMP_INIT(read, INTUSE(_IO_file_read)),
JUMP_INIT(write, _IO_new_file_write),
JUMP_INIT(seek, INTUSE(_IO_file_seek)),
JUMP_INIT(close, _IO_file_close),
JUMP_INIT(stat, INTUSE(_IO_file_stat)),
JUMP_INIT(showmanyc, _IO_default_showmanyc),
JUMP_INIT(imbue, _IO_default_imbue)
};
#ifdef _LIBC
versioned_symbol (libc, _IO_new_do_write, _IO_do_write, GLIBC_2_1);
versioned_symbol (libc, _IO_new_file_attach, _IO_file_attach, GLIBC_2_1);