*/
#include "cache.h"
+static int stage = 0;
+
static int read_one_entry(unsigned char *sha1, const char *base, int baselen, const char *pathname, unsigned mode)
{
int len = strlen(pathname);
memset(ce, 0, size);
- ce->ce_mode = htonl(mode);
- ce->ce_namelen = htons(baselen + len);
+ ce->ce_mode = create_ce_mode(mode);
+ ce->ce_flags = create_ce_flags(baselen + len, stage);
memcpy(ce->name, base, baselen);
memcpy(ce->name + baselen, pathname, len+1);
memcpy(ce->sha1, sha1, 20);
unlink(".git/index.lock");
}
+static int path_matches(struct cache_entry *a, struct cache_entry *b)
+{
+ int len = ce_namelen(a);
+ return ce_namelen(b) == len &&
+ !memcmp(a->name, b->name, len);
+}
+
+static int same(struct cache_entry *a, struct cache_entry *b)
+{
+ return a->ce_mode == b->ce_mode &&
+ !memcmp(a->sha1, b->sha1, 20);
+}
+
+
+/*
+ * 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
+ * mode have changed?
+ *
+ * The trivial cases end up being the ones where two
+ * out of three files are the same:
+ * - both destinations the same, trivially take either
+ * - one of the destination versions hasn't changed,
+ * take the other.
+ *
+ * The "all entries exactly the same" case falls out as
+ * a special case of any of the "two same" cases.
+ *
+ * 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;
+ return NULL;
+}
+
+static void trivially_merge_cache(struct cache_entry **src, int nr)
+{
+ static struct cache_entry null_entry;
+ struct cache_entry **dst = src;
+ struct cache_entry *old = &null_entry;
+
+ while (nr) {
+ struct cache_entry *ce, *result;
+
+ ce = src[0];
+
+ /* We throw away original cache entries except for the stat information */
+ if (!ce_stage(ce)) {
+ old = ce;
+ src++;
+ nr--;
+ active_nr--;
+ continue;
+ }
+ if (nr > 2 && (result = merge_entries(ce, src[1], src[2])) != NULL) {
+ /*
+ * See if we can re-use the old CE directly?
+ * That way we get the uptodate stat info.
+ */
+ if (path_matches(result, old) && same(result, old))
+ *result = *old;
+ ce = result;
+ ce->ce_flags &= ~htons(CE_STAGEMASK);
+ src += 2;
+ nr -= 2;
+ active_nr -= 2;
+ }
+ *dst++ = ce;
+ src++;
+ nr--;
+ }
+}
+
+static void merge_stat_info(struct cache_entry **src, int nr)
+{
+ static struct cache_entry null_entry;
+ struct cache_entry **dst = src;
+ struct cache_entry *old = &null_entry;
+
+ while (nr) {
+ struct cache_entry *ce;
+
+ ce = src[0];
+
+ /* We throw away original cache entries except for the stat information */
+ if (!ce_stage(ce)) {
+ old = ce;
+ src++;
+ nr--;
+ active_nr--;
+ continue;
+ }
+ if (path_matches(ce, old) && same(ce, old))
+ *ce = *old;
+ ce->ce_flags &= ~htons(CE_STAGEMASK);
+ *dst++ = ce;
+ src++;
+ nr--;
+ }
+}
+
int main(int argc, char **argv)
{
- int i, newfd;
+ int i, newfd, merge;
unsigned char sha1[20];
newfd = open(".git/index.lock", O_RDWR | O_CREAT | O_EXCL, 0600);
atexit(remove_lock_file);
remove_lock = 1;
+ merge = 0;
for (i = 1; i < argc; i++) {
const char *arg = argv[i];
- /* "-m" stands for "merge" current directory cache */
+ /* "-m" stands for "merge", meaning we start in stage 1 */
if (!strcmp(arg, "-m")) {
- if (active_cache)
- die("read-tree: cannot merge old cache on top of new");
- if (read_cache() < 0)
- die("read-tree: corrupt directory cache");
+ int i;
+ if (stage)
+ usage("-m needs to come first");
+ read_cache();
+ for (i = 0; i < active_nr; i++) {
+ if (ce_stage(active_cache[i]))
+ usage("you need to resolve your current index first");
+ }
+ stage = 1;
+ merge = 1;
continue;
}
if (get_sha1_hex(arg, sha1) < 0)
usage("read-tree [-m] <sha1>");
+ if (stage > 3)
+ usage("can't merge more than two trees");
if (read_tree(sha1, "", 0) < 0)
die("failed to unpack tree object %s", arg);
+ stage++;
+ }
+ if (merge) {
+ switch (stage) {
+ case 4: /* Three-way merge */
+ trivially_merge_cache(active_cache, active_nr);
+ break;
+ case 2: /* Just read a tree, merge with old cache contents */
+ merge_stat_info(active_cache, active_nr);
+ break;
+ default:
+ die("just how do you expect me to merge %d trees?", stage-1);
+ }
}
if (write_cache(newfd, active_cache, active_nr) ||
rename(".git/index.lock", ".git/index"))