/*
* This removes all trivial merges that don't change the tree
* and collapses them to state 0.
- *
- * _Any_ other merge is left to user policy. That includes "both
- * created the same file", and "both removed the same file" - which are
- * trivial, but the user might still want to _note_ it.
*/
static struct cache_entry *merge_entries(struct cache_entry *a,
struct cache_entry *b,
struct cache_entry *c)
{
- int len = ce_namelen(a);
-
- /*
- * Are they all the same filename? We won't do
- * any name merging
- */
- if (ce_namelen(b) != len ||
- ce_namelen(c) != len ||
- memcmp(a->name, b->name, len) ||
- memcmp(a->name, c->name, len))
- return NULL;
-
/*
* Ok, all three entries describe the same
* filename, but maybe the contents or file
* Here "a" is "original", and "b" and "c" are the two
* trees we are merging.
*/
- if (same(b,c))
- return c;
- if (same(a,b))
- return c;
- if (same(a,c))
- return b;
+ if (a && b && c) {
+ if (same(b,c))
+ return c;
+ if (same(a,b))
+ return c;
+ if (same(a,c))
+ return b;
+ }
return NULL;
}
die("Entry '%s' would be overwritten by merge. Cannot merge.", ce->name);
}
-#define CHECK_OLD(ce) if (old && same(old, ce)) { verify_uptodate(old); old = NULL; }
-
-static void trivially_merge_cache(struct cache_entry **src, int nr)
+static int merged_entry(struct cache_entry *merge, struct cache_entry *old, struct cache_entry **dst)
{
- struct cache_entry **dst = src;
- struct cache_entry *old = NULL;
-
- while (nr--) {
- struct cache_entry *ce, *result;
-
- ce = *src++;
-
- /* We throw away original cache entries except for the stat information */
- if (!ce_stage(ce)) {
- if (old)
- reject_merge(old);
- old = ce;
- active_nr--;
- continue;
- }
- if (old && !path_matches(old, ce))
- reject_merge(old);
- if (nr > 1 && (result = merge_entries(ce, src[0], src[1])) != NULL) {
- result->ce_flags |= htons(CE_UPDATE);
- /*
- * See if we can re-use the old CE directly?
- * That way we get the uptodate stat info.
- *
- * This also removes the UPDATE flag on
- * a match.
- */
- if (old && same(old, result)) {
- *result = *old;
- old = NULL;
- }
- CHECK_OLD(ce);
- CHECK_OLD(src[0]);
- CHECK_OLD(src[1]);
- ce = result;
- ce->ce_flags &= ~htons(CE_STAGEMASK);
- src += 2;
- nr -= 2;
- active_nr -= 2;
- }
-
+ merge->ce_flags |= htons(CE_UPDATE);
+ if (old) {
/*
- * If we had an old entry that we now effectively
- * overwrite, make sure it wasn't dirty.
+ * See if we can re-use the old CE directly?
+ * That way we get the uptodate stat info.
+ *
+ * This also removes the UPDATE flag on
+ * a match.
*/
- CHECK_OLD(ce);
- *dst++ = ce;
+ if (same(old, merge)) {
+ *merge = *old;
+ } else {
+ verify_uptodate(old);
+ }
}
- if (old)
- reject_merge(old);
+ merge->ce_flags &= ~htons(CE_STAGEMASK);
+ *dst++ = merge;
+ return 1;
}
-/*
- * When we find a "stage2" entry in the two-way merge, that's
- * the one that will remain. If we have an exact old match,
- * we don't care whether the file is up-to-date or not, we just
- * re-use the thing directly.
- *
- * If we didn't have an exact match, then we want to make sure
- * that we've seen a stage1 that matched the old, and that the
- * old file was up-to-date. Because it will be gone after this
- * merge..
- */
-static void twoway_check(struct cache_entry *old, int seen_stage1, struct cache_entry *ce)
+static int threeway_merge(struct cache_entry *stages[4], struct cache_entry **dst)
{
- if (path_matches(old, ce)) {
- /*
- * This also removes the UPDATE flag on
- * a match
- */
- if (same(old, ce)) {
- *ce = *old;
- return;
- }
- if (!seen_stage1)
- reject_merge(old);
+ struct cache_entry *old = stages[0];
+ struct cache_entry *a = stages[1], *b = stages[2], *c = stages[3];
+ struct cache_entry *merge;
+ int count;
+
+ /*
+ * If we have an entry in the index cache ("old"), then we want
+ * to make sure that it matches any entries in stage 2 ("first
+ * branch", aka "b").
+ */
+ if (old) {
+ if (!b || !same(old, b))
+ return -1;
}
- verify_uptodate(old);
+ merge = merge_entries(a, b, c);
+ if (merge)
+ return merged_entry(merge, old, dst);
+ if (old)
+ verify_uptodate(old);
+ count = 0;
+ if (a) { *dst++ = a; count++; }
+ if (b) { *dst++ = b; count++; }
+ if (c) { *dst++ = c; count++; }
+ return count;
}
/*
* - if the current entry matches the new tree, we leave it
* as-is. Otherwise we require that it be up-to-date.
*/
-static void twoway_merge(struct cache_entry **src, int nr)
+static int twoway_merge(struct cache_entry **src, struct cache_entry **dst)
{
- int seen_stage1 = 0;
- struct cache_entry *old = NULL;
- struct cache_entry **dst = src;
-
- while (nr--) {
- struct cache_entry *ce = *src++;
- int stage = ce_stage(ce);
+ struct cache_entry *old = src[0];
+ struct cache_entry *a = src[1], *b = src[2];
- switch (stage) {
- case 0:
- if (old)
- reject_merge(old);
- old = ce;
- seen_stage1 = 0;
- active_nr--;
- continue;
-
- case 1:
- active_nr--;
- if (!old)
- continue;
- if (!path_matches(old, ce) || !same(old, ce))
- reject_merge(old);
- seen_stage1 = 1;
- continue;
-
- case 2:
- ce->ce_flags |= htons(CE_UPDATE);
- if (old) {
- twoway_check(old, seen_stage1, ce);
- old = NULL;
- }
- ce->ce_flags &= ~htons(CE_STAGEMASK);
- *dst++ = ce;
- continue;
- }
- die("impossible two-way stage");
- }
+ if (src[3])
+ return -1;
- /*
- * Unmatched with a new entry? Make sure it was
- * at least uptodate in the working directory _and_
- * the original tree..
- */
if (old) {
- if (!seen_stage1)
- reject_merge(old);
- verify_uptodate(old);
+ if (!a || !same(old, a))
+ return -1;
}
+ if (b)
+ return merged_entry(b, old, dst);
+ if (old)
+ verify_uptodate(old);
+ return 0;
}
-static void merge_stat_info(struct cache_entry **src, int nr)
+/*
+ * One-way merge.
+ *
+ * The rule is:
+ * - take the stat information from stage0, take the data from stage1
+ */
+static int oneway_merge(struct cache_entry **src, struct cache_entry **dst)
{
- static struct cache_entry null_entry;
- struct cache_entry **dst = src;
- struct cache_entry *stat = &null_entry;
+ struct cache_entry *old = src[0];
+ struct cache_entry *a = src[1];
- while (nr--) {
- struct cache_entry *ce = *src++;
+ if (src[2] || src[3])
+ return -1;
- /* We throw away original cache entries except for the stat information */
- if (!ce_stage(ce)) {
- stat = ce;
- active_nr--;
- continue;
- }
- if (path_matches(ce, stat) && same(ce, stat))
- *ce = *stat;
- ce->ce_flags &= ~htons(CE_STAGEMASK);
- *dst++ = ce;
- }
+ if (!a)
+ return 0;
+ if (old && same(old, a))
+ *a = *old;
+ a->ce_flags &= ~htons(CE_STAGEMASK);
+ *dst++ = a;
+ return 1;
}
static void check_updates(struct cache_entry **src, int nr)
}
}
+static void merge_cache(struct cache_entry **src, int nr, int (*fn)(struct cache_entry **, struct cache_entry **))
+{
+ struct cache_entry **dst = src;
+
+ while (nr) {
+ int entries;
+ struct cache_entry *name, *ce, *stages[4] = { NULL, };
+
+ name = ce = *src;
+ for (;;) {
+ int stage = ce_stage(ce);
+ stages[stage] = ce;
+ ce = *++src;
+ active_nr--;
+ if (!--nr)
+ break;
+ if (!path_matches(ce, name))
+ break;
+ }
+
+ entries = fn(stages, dst);
+ if (entries < 0)
+ reject_merge(name);
+ dst += entries;
+ active_nr += entries;
+ }
+ check_updates(active_cache, active_nr);
+}
+
static char *read_tree_usage = "git-read-tree (<sha> | -m <sha1> [<sha2> [<sha3>]])";
static struct cache_file cache_file;
if (merge) {
switch (stage) {
case 4: /* Three-way merge */
- trivially_merge_cache(active_cache, active_nr);
- check_updates(active_cache, active_nr);
+ merge_cache(active_cache, active_nr, threeway_merge);
break;
case 3: /* Update from one tree to another */
- twoway_merge(active_cache, active_nr);
+ merge_cache(active_cache, active_nr, twoway_merge);
check_updates(active_cache, active_nr);
break;
case 2: /* Just read a tree, merge with old cache contents */
- merge_stat_info(active_cache, active_nr);
+ merge_cache(active_cache, active_nr, oneway_merge);
break;
default:
die("just how do you expect me to merge %d trees?", stage-1);
projects / git.git / commitdiff