* The delta-parsing part is almost straight copy of patch-delta.c
* which is (C) 2005 Nicolas Pitre <nico@cam.org>.
*/
+#include "cache.h"
+#include "delta.h"
+#include "count-delta.h"
#include <stdlib.h>
#include <string.h>
#include <limits.h>
-#include "delta.h"
-#include "count-delta.h"
+
+struct span {
+ struct span *next;
+ unsigned long ofs;
+ unsigned long end;
+};
+
+static void touch_range(struct span **span,
+ unsigned long ofs, unsigned long end)
+{
+ struct span *e = *span;
+ struct span *p = NULL;
+
+ while (e && e->ofs <= ofs) {
+ again:
+ if (ofs < e->end) {
+ while (e->end < end) {
+ if (e->next && e->next->ofs <= end) {
+ e->end = e->next->ofs;
+ e = e->next;
+ }
+ else {
+ e->end = end;
+ return;
+ }
+ }
+ return;
+ }
+ p = e;
+ e = e->next;
+ }
+ if (e && e->ofs <= end) {
+ e->ofs = ofs;
+ goto again;
+ }
+ else {
+ e = xmalloc(sizeof(*e));
+ e->ofs = ofs;
+ e->end = end;
+ if (p) {
+ e->next = p->next;
+ p->next = e;
+ }
+ else {
+ e->next = *span;
+ *span = e;
+ }
+ }
+}
+
+static unsigned long count_range(struct span *s)
+{
+ struct span *t;
+ unsigned long sz = 0;
+ while (s) {
+ t = s;
+ sz += s->end - s->ofs;
+ s = s->next;
+ free(t);
+ }
+ return sz;
+}
/*
* NOTE. We do not _interpret_ delta fully. As an approximation, we
*
* Number of bytes that are _not_ copied from the source is deletion,
* and number of inserted literal bytes are addition, so sum of them
- * is the extent of damage. xdelta can express an edit that copies
- * data inside of the destination which originally came from the
- * source. We do not count that in the following routine, so we are
- * undercounting the source material that remains in the final output
- * that way.
+ * is the extent of damage.
*/
int count_delta(void *delta_buf, unsigned long delta_size,
unsigned long *src_copied, unsigned long *literal_added)
{
- unsigned long copied_from_source, added_literal;
+ unsigned long added_literal;
const unsigned char *data, *top;
unsigned char cmd;
unsigned long src_size, dst_size, out;
+ struct span *span = NULL;
if (delta_size < DELTA_SIZE_MIN)
return -1;
src_size = get_delta_hdr_size(&data);
dst_size = get_delta_hdr_size(&data);
- added_literal = copied_from_source = out = 0;
+ added_literal = out = 0;
while (data < top) {
cmd = *data++;
if (cmd & 0x80) {
if (cmd & 0x40) cp_size |= (*data++ << 16);
if (cp_size == 0) cp_size = 0x10000;
- copied_from_source += cp_size;
+ touch_range(&span, cp_off, cp_off+cp_size);
out += cp_size;
} else {
/* write literal into dst */
}
}
+ *src_copied = count_range(span);
+
/* sanity check */
if (data != top || out != dst_size)
return -1;
/* delete size is what was _not_ copied from source.
* edit size is that and literal additions.
*/
- *src_copied = copied_from_source;
*literal_added = added_literal;
return 0;
}