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* libio/fileops.c (_IO_file_seekoff_mmap): Leave read pointers at EOF

if seek would go past it.
	(mmap_remap_check): If file position is at or past EOF after check,
	leave read pointers at EOF and don't seek.

	* libio/tst-mmap-offend.c: New file.
	* libio/Makefile (tests): Add it.
This commit is contained in:
Roland McGrath
2002-08-15 23:57:00 +00:00
parent 8f83366e13
commit fc77d66abf
4 changed files with 126 additions and 15 deletions

View File

@ -665,22 +665,30 @@ mmap_remap_check (_IO_FILE *fp)
# 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,
_IO_setg (fp, fp->_IO_buf_base,
fp->_offset < fp->_IO_buf_end - fp->_IO_buf_base
? fp->_IO_buf_base + fp->_offset : fp->_IO_buf_end,
fp->_IO_buf_end);
if (
# ifdef _G_LSEEK64
_G_LSEEK64
# else
__lseek
# endif
(fp->_fileno, fp->_IO_buf_end - fp->_IO_buf_base, SEEK_SET)
!= fp->_IO_buf_end - fp->_IO_buf_base)
/* If we are already positioned at or past the end of the file, don't
change the current offset. If not, seek past what we have mapped,
mimicking the position left by a normal underflow reading into its
buffer until EOF. */
if (fp->_offset < fp->_IO_buf_end - fp->_IO_buf_base)
{
fp->_flags |= _IO_ERR_SEEN;
return EOF;
if (
# ifdef _G_LSEEK64
_G_LSEEK64
# else
__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;
else
fp->_offset = fp->_IO_buf_end - fp->_IO_buf_base;
}
fp->_offset = fp->_IO_buf_end - fp->_IO_buf_base;
return 0;
}
@ -1152,8 +1160,17 @@ _IO_file_seekoff_mmap (fp, offset, dir, mode)
if (result < 0)
return EOF;
_IO_setg (fp, fp->_IO_buf_base, fp->_IO_buf_base + offset,
fp->_IO_buf_base + offset);
if (offset > fp->_IO_buf_end - fp->_IO_buf_base)
/* One can fseek arbitrarily past the end of the file
and it is meaningless until one attempts to read.
Leave the buffer pointers in EOF state until underflow. */
_IO_setg (fp, fp->_IO_buf_base, fp->_IO_buf_end, fp->_IO_buf_end);
else
/* Adjust the read pointers to match the file position,
but so the next read attempt will call underflow. */
_IO_setg (fp, fp->_IO_buf_base, fp->_IO_buf_base + offset,
fp->_IO_buf_base + offset);
fp->_offset = result;
_IO_mask_flags (fp, 0, _IO_EOF_SEEN);