int
_IO_default_pbackfail (_IO_FILE *fp, int c)
{
if (fp->_IO_read_ptr > fp->_IO_read_base && !_IO_in_backup (fp)
&& (unsigned char) fp->_IO_read_ptr[-1] == c)
--fp->_IO_read_ptr;
else
{
/* Need to handle a filebuf in write mode (switch to read mode). FIXME!*/
if (!_IO_in_backup (fp))
{
/* We need to keep the invariant that the main get area
logically follows the backup area. */
if (fp->_IO_read_ptr > fp->_IO_read_base && _IO_have_backup (fp))
{
if (save_for_backup (fp, fp->_IO_read_ptr))
return EOF;
}
else if (!_IO_have_backup (fp))
{
/* No backup buffer: allocate one. */
/* Use nshort buffer, if unused? (probably not) FIXME */
int backup_size = 128;
char *bbuf = (char *) malloc (backup_size);
if (bbuf == NULL)
return EOF;
fp->_IO_save_base = bbuf;
fp->_IO_save_end = fp->_IO_save_base + backup_size;
fp->_IO_backup_base = fp->_IO_save_end;
}
fp->_IO_read_base = fp->_IO_read_ptr;
_IO_switch_to_backup_area (fp);
}
else if (fp->_IO_read_ptr <= fp->_IO_read_base)
{
/* Increase size of existing backup buffer. */
_IO_size_t new_size;
_IO_size_t old_size = fp->_IO_read_end - fp->_IO_read_base;
char *new_buf;
new_size = 2 * old_size;
new_buf = (char *) malloc (new_size);
if (new_buf == NULL)
return EOF;
memcpy (new_buf + (new_size - old_size), fp->_IO_read_base,
old_size);
free (fp->_IO_read_base);
_IO_setg (fp, new_buf, new_buf + (new_size - old_size),
new_buf + new_size);
fp->_IO_backup_base = fp->_IO_read_ptr;
}
*--fp->_IO_read_ptr = c;
}
return (unsigned char) c;
}
int
_IO_seekmark (_IO_FILE *fp, struct _IO_marker *mark, int delta)
{
if (mark->_sbuf != fp)
return EOF;
if (mark->_pos >= 0)
{
if (_IO_in_backup (fp))
_IO_switch_to_main_get_area (fp);
fp->_IO_read_ptr = fp->_IO_read_base + mark->_pos;
}
else
{
if (!_IO_in_backup (fp))
_IO_switch_to_backup_area (fp);
fp->_IO_read_ptr = fp->_IO_read_end + mark->_pos;
}
return 0;
}
_IO_off64_t
attribute_compat_text_section
_IO_old_file_seekoff (_IO_FILE *fp, _IO_off64_t offset, int dir, int mode)
{
_IO_off_t result;
_IO_off64_t delta, new_offset;
long count;
/* POSIX.1 8.2.3.7 says that after a call the fflush() the file
offset of the underlying file must be exact. */
int must_be_exact = (fp->_IO_read_base == fp->_IO_read_end
&& fp->_IO_write_base == fp->_IO_write_ptr);
if (mode == 0)
dir = _IO_seek_cur, offset = 0; /* Don't move any pointers. */
/* Flush unwritten characters.
(This may do an unneeded write if we seek within the buffer.
But to be able to switch to reading, we would need to set
egptr to pptr. That can't be done in the current design,
which assumes file_ptr() is eGptr. Anyway, since we probably
end up flushing when we close(), it doesn't make much difference.)
FIXME: simulate mem-mapped files. */
if (fp->_IO_write_ptr > fp->_IO_write_base || _IO_in_put_mode (fp))
if (_IO_switch_to_get_mode (fp))
return EOF;
if (fp->_IO_buf_base == NULL)
{
/* It could be that we already have a pushback buffer. */
if (fp->_IO_read_base != NULL)
{
free (fp->_IO_read_base);
fp->_flags &= ~_IO_IN_BACKUP;
}
_IO_doallocbuf (fp);
_IO_setp (fp, fp->_IO_buf_base, fp->_IO_buf_base);
_IO_setg (fp, fp->_IO_buf_base, fp->_IO_buf_base, fp->_IO_buf_base);
}
switch (dir)
{
case _IO_seek_cur:
/* Adjust for read-ahead (bytes is buffer). */
offset -= fp->_IO_read_end - fp->_IO_read_ptr;
if (fp->_old_offset == _IO_pos_BAD)
goto dumb;
/* Make offset absolute, assuming current pointer is file_ptr(). */
offset += fp->_old_offset;
dir = _IO_seek_set;
break;
case _IO_seek_set:
break;
case _IO_seek_end:
{
struct stat64 st;
if (_IO_SYSSTAT (fp, &st) == 0 && S_ISREG (st.st_mode))
{
offset += st.st_size;
dir = _IO_seek_set;
}
else
goto dumb;
}
}
/* At this point, dir==_IO_seek_set. */
/* If we are only interested in the current position we've found it now. */
if (mode == 0)
return offset;
/* If destination is within current buffer, optimize: */
if (fp->_old_offset != _IO_pos_BAD && fp->_IO_read_base != NULL
&& !_IO_in_backup (fp))
{
/* Offset relative to start of main get area. */
_IO_off_t rel_offset = (offset - fp->_old_offset
+ (fp->_IO_read_end - fp->_IO_read_base));
if (rel_offset >= 0)
{
#if 0
if (_IO_in_backup (fp))
_IO_switch_to_main_get_area (fp);
#endif
if (rel_offset <= fp->_IO_read_end - fp->_IO_read_base)
{
_IO_setg (fp, fp->_IO_buf_base, fp->_IO_buf_base + rel_offset,
fp->_IO_read_end);
_IO_setp (fp, fp->_IO_buf_base, fp->_IO_buf_base);
{
_IO_mask_flags (fp, 0, _IO_EOF_SEEN);
goto resync;
}
}
#ifdef TODO
/* If we have streammarkers, seek forward by reading ahead. */
if (_IO_have_markers (fp))
{
int to_skip = rel_offset
- (fp->_IO_read_ptr - fp->_IO_read_base);
if (ignore (to_skip) != to_skip)
goto dumb;
_IO_mask_flags (fp, 0, _IO_EOF_SEEN);
goto resync;
}
#endif
}
#ifdef TODO
if (rel_offset < 0 && rel_offset >= Bbase () - Bptr ())
{
if (!_IO_in_backup (fp))
_IO_switch_to_backup_area (fp);
gbump (fp->_IO_read_end + rel_offset - fp->_IO_read_ptr);
_IO_mask_flags (fp, 0, _IO_EOF_SEEN);
goto resync;
}
#endif
}
#ifdef TODO
_IO_unsave_markers (fp);
#endif
if (fp->_flags & _IO_NO_READS)
goto dumb;
/* Try to seek to a block boundary, to improve kernel page management. */
new_offset = offset & ~(fp->_IO_buf_end - fp->_IO_buf_base - 1);
delta = offset - new_offset;
if (delta > fp->_IO_buf_end - fp->_IO_buf_base)
{
new_offset = offset;
delta = 0;
}
result = _IO_SYSSEEK (fp, new_offset, 0);
if (result < 0)
return EOF;
if (delta == 0)
count = 0;
else
{
count = _IO_SYSREAD (fp, fp->_IO_buf_base,
(must_be_exact
? delta : fp->_IO_buf_end - fp->_IO_buf_base));
if (count < delta)
{
/* We weren't allowed to read, but try to seek the remainder. */
offset = count == EOF ? delta : delta-count;
dir = _IO_seek_cur;
goto dumb;
}
}
_IO_setg (fp, fp->_IO_buf_base, fp->_IO_buf_base + delta,
fp->_IO_buf_base + count);
_IO_setp (fp, fp->_IO_buf_base, fp->_IO_buf_base);
fp->_old_offset = result + count;
_IO_mask_flags (fp, 0, _IO_EOF_SEEN);
return offset;
dumb:
_IO_unsave_markers (fp);
result = _IO_SYSSEEK (fp, offset, dir);
if (result != EOF)
{
_IO_mask_flags (fp, 0, _IO_EOF_SEEN);
fp->_old_offset = result;
_IO_setg (fp, fp->_IO_buf_base, fp->_IO_buf_base, fp->_IO_buf_base);
_IO_setp (fp, fp->_IO_buf_base, fp->_IO_buf_base);
}
return result;
resync:
/* We need to do it since it is possible that the file offset in
the kernel may be changed behind our back. It may happen when
we fopen a file and then do a fork. One process may access the
file and the kernel file offset will be changed. */
if (fp->_old_offset >= 0)
_IO_SYSSEEK (fp, fp->_old_offset, 0);
return offset;
}
