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diff --git a/commit.c b/commit.c
index 946615d2ad5c364fe63b201aa9a9574737804c38..c6bf10d045a45a38352af0a7dc0b3732b7493182 100644 (file)
--- a/commit.c
+++ b/commit.c
int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
{
+ char *tail = buffer;
char *bufptr = buffer;
unsigned char parent[20];
struct commit_list **pptr;
if (item->object.parsed)
return 0;
item->object.parsed = 1;
- if (memcmp(bufptr, "tree ", 5))
+ tail += size;
+ if (tail <= bufptr + 5 || memcmp(bufptr, "tree ", 5))
return error("bogus commit object %s", sha1_to_hex(item->object.sha1));
- if (get_sha1_hex(bufptr + 5, parent) < 0)
+ if (tail <= bufptr + 45 || get_sha1_hex(bufptr + 5, parent) < 0)
return error("bad tree pointer in commit %s",
sha1_to_hex(item->object.sha1));
item->tree = lookup_tree(parent);
@@ -257,10 +259,12 @@ int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
pptr = &item->parents;
graft = lookup_commit_graft(item->object.sha1);
- while (!memcmp(bufptr, "parent ", 7)) {
+ while (bufptr + 48 < tail && !memcmp(bufptr, "parent ", 7)) {
struct commit *new_parent;
- if (get_sha1_hex(bufptr + 7, parent) || bufptr[47] != '\n')
+ if (tail <= bufptr + 48 ||
+ get_sha1_hex(bufptr + 7, parent) ||
+ bufptr[47] != '\n')
return error("bad parents in commit %s", sha1_to_hex(item->object.sha1));
bufptr += 48;
if (graft)
{
struct commit_list *parents;
- parents = commit->parents;
commit->object.flags &= ~mark;
+ parents = commit->parents;
while (parents) {
struct commit *parent = parents->item;
- if (parent && parent->object.parsed &&
- (parent->object.flags & mark))
+
+ /* Have we already cleared this? */
+ if (mark & parent->object.flags)
clear_commit_marks(parent, mark);
parents = parents->next;
}
@@ -543,7 +548,7 @@ static int add_merge_info(enum cmit_fmt fmt, char *buf, const struct commit *com
const char *hex = abbrev
? find_unique_abbrev(p->object.sha1, abbrev)
: sha1_to_hex(p->object.sha1);
- char *dots = (abbrev && strlen(hex) != 40) ? "..." : "";
+ const char *dots = (abbrev && strlen(hex) != 40) ? "..." : "";
parent = parent->next;
offset += sprintf(buf + offset, " %s%s", hex, dots);
}
free(nodes);
}
+
+/* merge-rebase stuff */
+
+/* bits #0..7 in revision.h */
+#define PARENT1 (1u<< 8)
+#define PARENT2 (1u<< 9)
+#define STALE (1u<<10)
+
+static struct commit *interesting(struct commit_list *list)
+{
+ while (list) {
+ struct commit *commit = list->item;
+ list = list->next;
+ if (commit->object.flags & STALE)
+ continue;
+ return commit;
+ }
+ return NULL;
+}
+
+/*
+ * A pathological example of how this thing works.
+ *
+ * Suppose we had this commit graph, where chronologically
+ * the timestamp on the commit are A <= B <= C <= D <= E <= F
+ * and we are trying to figure out the merge base for E and F
+ * commits.
+ *
+ * F
+ * / \
+ * E A D
+ * \ / /
+ * B /
+ * \ /
+ * C
+ *
+ * First we push E and F to list to be processed. E gets bit 1
+ * and F gets bit 2. The list becomes:
+ *
+ * list=F(2) E(1), result=empty
+ *
+ * Then we pop F, the newest commit, from the list. Its flag is 2.
+ * We scan its parents, mark them reachable from the side that F is
+ * reachable from, and push them to the list:
+ *
+ * list=E(1) D(2) A(2), result=empty
+ *
+ * Next pop E and do the same.
+ *
+ * list=D(2) B(1) A(2), result=empty
+ *
+ * Next pop D and do the same.
+ *
+ * list=C(2) B(1) A(2), result=empty
+ *
+ * Next pop C and do the same.
+ *
+ * list=B(1) A(2), result=empty
+ *
+ * Now it is B's turn. We mark its parent, C, reachable from B's side,
+ * and push it to the list:
+ *
+ * list=C(3) A(2), result=empty
+ *
+ * Now pop C and notice it has flags==3. It is placed on the result list,
+ * and the list now contains:
+ *
+ * list=A(2), result=C(3)
+ *
+ * We pop A and do the same.
+ *
+ * list=B(3), result=C(3)
+ *
+ * Next, we pop B and something very interesting happens. It has flags==3
+ * so it is also placed on the result list, and its parents are marked
+ * stale, retroactively, and placed back on the list:
+ *
+ * list=C(7), result=C(7) B(3)
+ *
+ * Now, list does not have any interesting commit. So we find the newest
+ * commit from the result list that is not marked stale. Which is
+ * commit B.
+ *
+ *
+ * Another pathological example how this thing used to fail to mark an
+ * ancestor of a merge base as STALE before we introduced the
+ * postprocessing phase (mark_reachable_commits).
+ *
+ * 2
+ * H
+ * 1 / \
+ * G A \
+ * |\ / \
+ * | B \
+ * | \ \
+ * \ C F
+ * \ \ /
+ * \ D /
+ * \ | /
+ * \| /
+ * E
+ *
+ * list A B C D E F G H
+ * G1 H2 - - - - - - 1 2
+ * H2 E1 B1 - 1 - - 1 - 1 2
+ * F2 E1 B1 A2 2 1 - - 1 2 1 2
+ * E3 B1 A2 2 1 - - 3 2 1 2
+ * B1 A2 2 1 - - 3 2 1 2
+ * C1 A2 2 1 1 - 3 2 1 2
+ * D1 A2 2 1 1 1 3 2 1 2
+ * A2 2 1 1 1 3 2 1 2
+ * B3 2 3 1 1 3 2 1 2
+ * C7 2 3 7 1 3 2 1 2
+ *
+ * At this point, unfortunately, everybody in the list is
+ * stale, so we fail to complete the following two
+ * steps to fully marking stale commits.
+ *
+ * D7 2 3 7 7 3 2 1 2
+ * E7 2 3 7 7 7 2 1 2
+ *
+ * and we ended up showing E as an interesting merge base.
+ * The postprocessing phase re-injects C and continues traversal
+ * to contaminate D and E.
+ */
+
+static void mark_reachable_commits(struct commit_list *result,
+ struct commit_list *list)
+{
+ struct commit_list *tmp;
+
+ /*
+ * Postprocess to fully contaminate the well.
+ */
+ for (tmp = result; tmp; tmp = tmp->next) {
+ struct commit *c = tmp->item;
+ /* Reinject stale ones to list,
+ * so we can scan their parents.
+ */
+ if (c->object.flags & STALE)
+ commit_list_insert(c, &list);
+ }
+ while (list) {
+ struct commit *c = list->item;
+ struct commit_list *parents;
+
+ tmp = list;
+ list = list->next;
+ free(tmp);
+
+ /* Anything taken out of the list is stale, so
+ * mark all its parents stale. We do not
+ * parse new ones (we already parsed all the relevant
+ * ones).
+ */
+ parents = c->parents;
+ while (parents) {
+ struct commit *p = parents->item;
+ parents = parents->next;
+ if (!(p->object.flags & STALE)) {
+ p->object.flags |= STALE;
+ commit_list_insert(p, &list);
+ }
+ }
+ }
+}
+
+struct commit_list *get_merge_bases(struct commit *rev1, struct commit *rev2,
+ int cleanup)
+{
+ struct commit_list *list = NULL;
+ struct commit_list *result = NULL;
+ struct commit_list *tmp = NULL;
+
+ if (rev1 == rev2)
+ return commit_list_insert(rev1, &result);
+
+ parse_commit(rev1);
+ parse_commit(rev2);
+
+ rev1->object.flags |= PARENT1;
+ rev2->object.flags |= PARENT2;
+ insert_by_date(rev1, &list);
+ insert_by_date(rev2, &list);
+
+ while (interesting(list)) {
+ struct commit *commit = list->item;
+ struct commit_list *parents;
+ int flags = commit->object.flags
+ & (PARENT1 | PARENT2 | STALE);
+
+ tmp = list;
+ list = list->next;
+ free(tmp);
+ if (flags == (PARENT1 | PARENT2)) {
+ insert_by_date(commit, &result);
+
+ /* Mark parents of a found merge stale */
+ flags |= STALE;
+ }
+ parents = commit->parents;
+ while (parents) {
+ struct commit *p = parents->item;
+ parents = parents->next;
+ if ((p->object.flags & flags) == flags)
+ continue;
+ parse_commit(p);
+ p->object.flags |= flags;
+ insert_by_date(p, &list);
+ }
+ }
+
+ if (!result)
+ goto finish;
+
+ if (result->next && list)
+ mark_reachable_commits(result, list);
+
+ /* cull duplicates */
+ for (tmp = result, list = NULL; tmp; ) {
+ struct commit *commit = tmp->item;
+ struct commit_list *next = tmp->next;
+ if (commit->object.flags & STALE) {
+ if (list != NULL)
+ list->next = next;
+ free(tmp);
+ } else {
+ if (list == NULL)
+ result = tmp;
+ list = tmp;
+ commit->object.flags |= STALE;
+ }
+
+ tmp = next;
+ }
+
+ finish:
+ if (cleanup) {
+ clear_commit_marks(rev1, PARENT1 | PARENT2 | STALE);
+ clear_commit_marks(rev2, PARENT1 | PARENT2 | STALE);
+ }
+
+ return result;
+}