Make sure the copy sequence is smaller than the list of tree entries it
is meant to replace. We do so by encoding tree entries in parallel with
the delta entry comparison, and then comparing the length of both
sequences.
Signed-off-by: Nicolas Pitre <nico@xxxxxxxxxxx>
---
packv4-create.c | 65 +++++++++++++++++++++++++++++++++++++++------------------
1 file changed, 45 insertions(+), 20 deletions(-)
diff --git a/packv4-create.c b/packv4-create.c
index 15c5959..c8d3053 100644
--- a/packv4-create.c
+++ b/packv4-create.c
@@ -433,7 +433,8 @@ void *pv4_encode_tree(void *_buffer, unsigned long *sizep,
struct tree_desc desc, delta_desc;
struct name_entry name_entry, delta_entry;
int nb_entries;
- unsigned int copy_start, copy_count = 0, delta_pos = 0, first_delta = 1;
+ unsigned int copy_start = 0, copy_count = 0, copy_pos = 0, copy_end = 0;
+ unsigned int delta_pos = 0, first_delta = 1;
if (!size)
return NULL;
@@ -489,24 +490,23 @@ void *pv4_encode_tree(void *_buffer, unsigned long *sizep,
if (ret == 0 && name_entry.mode == delta_entry.mode &&
hashcmp(name_entry.sha1, delta_entry.sha1) == 0) {
- if (!copy_count)
+ if (!copy_count) {
copy_start = delta_pos;
+ copy_pos = out - buffer;
+ copy_end = 0;
+ }
copy_count++;
delta_pos++;
if (!tree_entry(&delta_desc, &delta_entry))
delta = NULL;
- continue;
- }
- }
+ } else
+ copy_end = 1;
+ } else
+ copy_end = 1;
- if (end - out < 48) {
- unsigned long sofar = out - buffer;
- buffer = xrealloc(buffer, (sofar + 48)*2);
- end = buffer + (sofar + 48)*2;
- out = buffer + sofar;
- }
+ if (copy_count && copy_end) {
+ unsigned char copy_buf[48], *cp = copy_buf;
- if (copy_count) {
/*
* Let's write a sequence indicating we're copying
* entries from another object:
@@ -524,12 +524,31 @@ void *pv4_encode_tree(void *_buffer, unsigned long *sizep,
*/
copy_start = (copy_start << 1) | 1;
copy_count = (copy_count << 1) | first_delta;
- out += encode_varint(copy_start, out);
- out += encode_varint(copy_count, out);
+ cp += encode_varint(copy_start, cp);
+ cp += encode_varint(copy_count, cp);
if (first_delta)
- out += encode_sha1ref(delta_sha1, out);
+ cp += encode_sha1ref(delta_sha1, cp);
copy_count = 0;
- first_delta = 0;
+
+ /*
+ * Now let's make sure this is going to take less
+ * space than the corresponding direct entries we've
+ * created in parallel. If so we dump the copy
+ * sequence over those entries in the output buffer.
+ */
+ if (cp - copy_buf < out - &buffer[copy_pos]) {
+ out = buffer + copy_pos;
+ memcpy(out, copy_buf, cp - copy_buf);
+ out += cp - copy_buf;
+ first_delta = 0;
+ }
+ }
+
+ if (end - out < 48) {
+ unsigned long sofar = out - buffer;
+ buffer = xrealloc(buffer, (sofar + 48)*2);
+ end = buffer + (sofar + 48)*2;
+ out = buffer + sofar;
}
pathlen = tree_entry_len(&name_entry);
@@ -545,13 +564,19 @@ void *pv4_encode_tree(void *_buffer, unsigned long *sizep,
}
if (copy_count) {
- /* flush the trailing copy */
+ /* process the trailing copy */
+ unsigned char copy_buf[48], *cp = copy_buf;
copy_start = (copy_start << 1) | 1;
copy_count = (copy_count << 1) | first_delta;
- out += encode_varint(copy_start, out);
- out += encode_varint(copy_count, out);
+ cp += encode_varint(copy_start, cp);
+ cp += encode_varint(copy_count, cp);
if (first_delta)
- out += encode_sha1ref(delta_sha1, out);
+ cp += encode_sha1ref(delta_sha1, cp);
+ if (cp - copy_buf < out - &buffer[copy_pos]) {
+ out = buffer + copy_pos;
+ memcpy(out, copy_buf, cp - copy_buf);
+ out += cp - copy_buf;
+ }
}
*sizep = out - buffer;
--
1.8.4.38.g317e65b
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