*
* Copyright (C) Linus Torvalds, 2005
*/
+#define DBRT_DEBUG 1
+
#include "cache.h"
-static int stage = 0;
+#include "object.h"
+#include "tree.h"
-static int unpack_tree(unsigned char *sha1)
-{
- void *buffer;
- unsigned long size;
- int ret;
+static int merge = 0;
+static int update = 0;
+static int index_only = 0;
+static int nontrivial_merge = 0;
+static int trivial_merges_only = 0;
- buffer = read_object_with_reference(sha1, "tree", &size, NULL);
- if (!buffer)
- return -1;
- ret = read_tree(buffer, size, stage);
- free(buffer);
- return ret;
-}
+static int head_idx = -1;
+static int merge_size = 0;
+
+static struct object_list *trees = NULL;
-static char *lockfile_name;
+static struct cache_entry df_conflict_entry = {
+};
-static void remove_lock_file(void)
+static struct tree_entry_list df_conflict_list = {
+ .name = NULL,
+ .next = &df_conflict_list
+};
+
+typedef int (*merge_fn_t)(struct cache_entry **src);
+
+static int entcmp(char *name1, int dir1, char *name2, int dir2)
{
- if (lockfile_name)
- unlink(lockfile_name);
+ int len1 = strlen(name1);
+ int len2 = strlen(name2);
+ int len = len1 < len2 ? len1 : len2;
+ int ret = memcmp(name1, name2, len);
+ unsigned char c1, c2;
+ if (ret)
+ return ret;
+ c1 = name1[len];
+ c2 = name2[len];
+ if (!c1 && dir1)
+ c1 = '/';
+ if (!c2 && dir2)
+ c2 = '/';
+ ret = (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
+ if (c1 && c2 && !ret)
+ ret = len1 - len2;
+ return ret;
}
-static int path_matches(struct cache_entry *a, struct cache_entry *b)
+static int unpack_trees_rec(struct tree_entry_list **posns, int len,
+ const char *base, merge_fn_t fn, int *indpos)
{
- int len = ce_namelen(a);
- return ce_namelen(b) == len &&
- !memcmp(a->name, b->name, len);
+ int baselen = strlen(base);
+ int src_size = len + 1;
+ do {
+ int i;
+ char *first;
+ int firstdir = 0;
+ int pathlen;
+ unsigned ce_size;
+ struct tree_entry_list **subposns;
+ struct cache_entry **src;
+ int any_files = 0;
+ int any_dirs = 0;
+ char *cache_name;
+ int ce_stage;
+
+ /* Find the first name in the input. */
+
+ first = NULL;
+ cache_name = NULL;
+
+ /* Check the cache */
+ if (merge && *indpos < active_nr) {
+ /* This is a bit tricky: */
+ /* If the index has a subdirectory (with
+ * contents) as the first name, it'll get a
+ * filename like "foo/bar". But that's after
+ * "foo", so the entry in trees will get
+ * handled first, at which point we'll go into
+ * "foo", and deal with "bar" from the index,
+ * because the base will be "foo/". The only
+ * way we can actually have "foo/bar" first of
+ * all the things is if the trees don't
+ * contain "foo" at all, in which case we'll
+ * handle "foo/bar" without going into the
+ * directory, but that's fine (and will return
+ * an error anyway, with the added unknown
+ * file case.
+ */
+
+ cache_name = active_cache[*indpos]->name;
+ if (strlen(cache_name) > baselen &&
+ !memcmp(cache_name, base, baselen)) {
+ cache_name += baselen;
+ first = cache_name;
+ } else {
+ cache_name = NULL;
+ }
+ }
+
+#if DBRT_DEBUG > 1
+ if (first)
+ printf("index %s\n", first);
+#endif
+ for (i = 0; i < len; i++) {
+ if (!posns[i] || posns[i] == &df_conflict_list)
+ continue;
+#if DBRT_DEBUG > 1
+ printf("%d %s\n", i + 1, posns[i]->name);
+#endif
+ if (!first || entcmp(first, firstdir,
+ posns[i]->name,
+ posns[i]->directory) > 0) {
+ first = posns[i]->name;
+ firstdir = posns[i]->directory;
+ }
+ }
+ /* No name means we're done */
+ if (!first)
+ return 0;
+
+ pathlen = strlen(first);
+ ce_size = cache_entry_size(baselen + pathlen);
+
+ src = xmalloc(sizeof(struct cache_entry *) * src_size);
+ memset(src, 0, sizeof(struct cache_entry *) * src_size);
+
+ subposns = xmalloc(sizeof(struct tree_list_entry *) * len);
+ memset(subposns, 0, sizeof(struct tree_list_entry *) * len);
+
+ if (cache_name && !strcmp(cache_name, first)) {
+ any_files = 1;
+ src[0] = active_cache[*indpos];
+ remove_cache_entry_at(*indpos);
+ }
+
+ for (i = 0; i < len; i++) {
+ struct cache_entry *ce;
+
+ if (!posns[i] ||
+ (posns[i] != &df_conflict_list &&
+ strcmp(first, posns[i]->name))) {
+ continue;
+ }
+
+ if (posns[i] == &df_conflict_list) {
+ src[i + merge] = &df_conflict_entry;
+ continue;
+ }
+
+ if (posns[i]->directory) {
+ any_dirs = 1;
+ parse_tree(posns[i]->item.tree);
+ subposns[i] = posns[i]->item.tree->entries;
+ posns[i] = posns[i]->next;
+ src[i + merge] = &df_conflict_entry;
+ continue;
+ }
+
+ if (!merge)
+ ce_stage = 0;
+ else if (i + 1 < head_idx)
+ ce_stage = 1;
+ else if (i + 1 > head_idx)
+ ce_stage = 3;
+ else
+ ce_stage = 2;
+
+ ce = xmalloc(ce_size);
+ memset(ce, 0, ce_size);
+ ce->ce_mode = create_ce_mode(posns[i]->mode);
+ ce->ce_flags = create_ce_flags(baselen + pathlen,
+ ce_stage);
+ memcpy(ce->name, base, baselen);
+ memcpy(ce->name + baselen, first, pathlen + 1);
+
+ any_files = 1;
+
+ memcpy(ce->sha1, posns[i]->item.any->sha1, 20);
+ src[i + merge] = ce;
+ subposns[i] = &df_conflict_list;
+ posns[i] = posns[i]->next;
+ }
+ if (any_files) {
+ if (merge) {
+ int ret;
+
+#if DBRT_DEBUG > 1
+ printf("%s:\n", first);
+ for (i = 0; i < src_size; i++) {
+ printf(" %d ", i);
+ if (src[i])
+ printf("%s\n", sha1_to_hex(src[i]->sha1));
+ else
+ printf("\n");
+ }
+#endif
+ ret = fn(src);
+
+#if DBRT_DEBUG > 1
+ printf("Added %d entries\n", ret);
+#endif
+ *indpos += ret;
+ } else {
+ for (i = 0; i < src_size; i++) {
+ if (src[i]) {
+ add_cache_entry(src[i], ADD_CACHE_OK_TO_ADD|ADD_CACHE_SKIP_DFCHECK);
+ }
+ }
+ }
+ }
+ if (any_dirs) {
+ char *newbase = xmalloc(baselen + 2 + pathlen);
+ memcpy(newbase, base, baselen);
+ memcpy(newbase + baselen, first, pathlen);
+ newbase[baselen + pathlen] = '/';
+ newbase[baselen + pathlen + 1] = '\0';
+ if (unpack_trees_rec(subposns, len, newbase, fn,
+ indpos))
+ return -1;
+ free(newbase);
+ }
+ free(subposns);
+ free(src);
+ } while (1);
}
-static int same(struct cache_entry *a, struct cache_entry *b)
+static void reject_merge(struct cache_entry *ce)
{
- return a->ce_mode == b->ce_mode &&
- !memcmp(a->sha1, b->sha1, 20);
+ die("Entry '%s' would be overwritten by merge. Cannot merge.",
+ ce->name);
}
+static void check_updates(struct cache_entry **src, int nr)
+{
+ static struct checkout state = {
+ .base_dir = "",
+ .force = 1,
+ .quiet = 1,
+ .refresh_cache = 1,
+ };
+ unsigned short mask = htons(CE_UPDATE);
+ while (nr--) {
+ struct cache_entry *ce = *src++;
+ if (!ce->ce_mode) {
+ if (update)
+ unlink(ce->name);
+ continue;
+ }
+ if (ce->ce_flags & mask) {
+ ce->ce_flags &= ~mask;
+ if (update)
+ checkout_entry(ce, &state);
+ }
+ }
+}
-/*
- * 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)
+static int unpack_trees(merge_fn_t fn)
{
- int len = ce_namelen(a);
+ int indpos = 0;
+ unsigned len = object_list_length(trees);
+ struct tree_entry_list **posns =
+ xmalloc(len * sizeof(struct tree_entry_list *));
+ int i;
+ struct object_list *posn = trees;
+ merge_size = len;
+ for (i = 0; i < len; i++) {
+ posns[i] = ((struct tree *) posn->item)->entries;
+ posn = posn->next;
+ }
+ if (unpack_trees_rec(posns, len, "", fn, &indpos))
+ return -1;
- /*
- * 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;
+ if (trivial_merges_only && nontrivial_merge)
+ die("Merge requires file-level merging");
- /*
- * 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;
+ check_updates(active_cache, active_nr);
+ return 0;
}
+static int list_tree(unsigned char *sha1)
+{
+ struct tree *tree = parse_tree_indirect(sha1);
+ if (!tree)
+ return -1;
+ object_list_append(&tree->object, &trees);
+ return 0;
+}
+
+static int same(struct cache_entry *a, struct cache_entry *b)
+{
+ if (!!a != !!b)
+ return 0;
+ if (!a && !b)
+ return 1;
+ return a->ce_mode == b->ce_mode &&
+ !memcmp(a->sha1, b->sha1, 20);
+}
+
+
/*
* When a CE gets turned into an unmerged entry, we
* want it to be up-to-date
{
struct stat st;
+ if (index_only)
+ return;
+
if (!lstat(ce->name, &st)) {
unsigned changed = ce_match_stat(ce, &st);
if (!changed)
die("Entry '%s' not uptodate. Cannot merge.", ce->name);
}
-/*
- * If the old tree contained a CE that isn't even in the
- * result, that's always a problem, regardless of whether
- * it's up-to-date or not (ie it can be a file that we
- * have updated but not committed yet).
- */
-static void reject_merge(struct cache_entry *ce)
+static int merged_entry(struct cache_entry *merge, struct cache_entry *old)
{
- die("Entry '%s' would be overwritten by merge. Cannot merge.", ce->name);
+ merge->ce_flags |= htons(CE_UPDATE);
+ if (old) {
+ /*
+ * 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 (same(old, merge)) {
+ *merge = *old;
+ } else {
+ verify_uptodate(old);
+ }
+ }
+ merge->ce_flags &= ~htons(CE_STAGEMASK);
+ add_cache_entry(merge, ADD_CACHE_OK_TO_ADD);
+ return 1;
}
-#define CHECK_OLD(ce) if (old && same(old, ce)) { verify_uptodate(old); old = NULL; }
+static int deleted_entry(struct cache_entry *ce, struct cache_entry *old)
+{
+ if (old)
+ verify_uptodate(old);
+ ce->ce_mode = 0;
+ add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
+ return 1;
+}
-static void trivially_merge_cache(struct cache_entry **src, int nr)
+static int keep_entry(struct cache_entry *ce)
{
- struct cache_entry **dst = src;
- struct cache_entry *old = NULL;
-
- 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)) {
- if (old)
- reject_merge(old);
- old = ce;
- src++;
- nr--;
- active_nr--;
- continue;
+ add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
+ return 1;
+}
+
+#if DBRT_DEBUG
+static void show_stage_entry(FILE *o,
+ const char *label, const struct cache_entry *ce)
+{
+ if (!ce)
+ fprintf(o, "%s (missing)\n", label);
+ else
+ fprintf(o, "%s%06o %s %d\t%s\n",
+ label,
+ ntohl(ce->ce_mode),
+ sha1_to_hex(ce->sha1),
+ ce_stage(ce),
+ ce->name);
+}
+#endif
+
+static int threeway_merge(struct cache_entry **stages)
+{
+ struct cache_entry *index;
+ struct cache_entry *head;
+ struct cache_entry *remote = stages[head_idx + 1];
+ int count;
+ int head_match = 0;
+ int remote_match = 0;
+
+ int df_conflict_head = 0;
+ int df_conflict_remote = 0;
+
+ int any_anc_missing = 0;
+ int i;
+
+ for (i = 1; i < head_idx; i++) {
+ if (!stages[i])
+ any_anc_missing = 1;
+ }
+
+ index = stages[0];
+ head = stages[head_idx];
+
+ if (head == &df_conflict_entry) {
+ df_conflict_head = 1;
+ head = NULL;
+ }
+
+ if (remote == &df_conflict_entry) {
+ df_conflict_remote = 1;
+ remote = NULL;
+ }
+
+ /* First, if there's a #16 situation, note that to prevent #13
+ * and #14.
+ */
+ if (!same(remote, head)) {
+ for (i = 1; i < head_idx; i++) {
+ if (same(stages[i], head)) {
+ head_match = i;
+ }
+ if (same(stages[i], remote)) {
+ remote_match = i;
+ }
}
- if (old && !path_matches(old, ce))
- reject_merge(old);
- 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 (old && same(old, result)) {
- *result = *old;
- old = NULL;
+ }
+
+ /* We start with cases where the index is allowed to match
+ * something other than the head: #14(ALT) and #2ALT, where it
+ * is permitted to match the result instead.
+ */
+ /* #14, #14ALT, #2ALT */
+ if (remote && !df_conflict_head && head_match && !remote_match) {
+ if (index && !same(index, remote) && !same(index, head))
+ reject_merge(index);
+ return merged_entry(remote, index);
+ }
+ /*
+ * If we have an entry in the index cache, then we want to
+ * make sure that it matches head.
+ */
+ if (index && !same(index, head)) {
+ reject_merge(index);
+ }
+
+ if (head) {
+ /* #5ALT, #15 */
+ if (same(head, remote))
+ return merged_entry(head, index);
+ /* #13, #3ALT */
+ if (!df_conflict_remote && remote_match && !head_match)
+ return merged_entry(head, index);
+ }
+
+ /* #1 */
+ if (!head && !remote && any_anc_missing)
+ return 0;
+
+ /* Below are "no merge" cases, which require that the index be
+ * up-to-date to avoid the files getting overwritten with
+ * conflict resolution files.
+ */
+ if (index) {
+ verify_uptodate(index);
+ }
+
+ nontrivial_merge = 1;
+
+ /* #2, #3, #4, #6, #7, #9, #11. */
+ count = 0;
+ if (!head_match || !remote_match) {
+ for (i = 1; i < head_idx; i++) {
+ if (stages[i]) {
+ keep_entry(stages[i]);
+ count++;
+ break;
}
- CHECK_OLD(ce);
- CHECK_OLD(src[1]);
- CHECK_OLD(src[2]);
- ce = result;
- ce->ce_flags &= ~htons(CE_STAGEMASK);
- src += 2;
- nr -= 2;
- active_nr -= 2;
}
+ }
+#if DBRT_DEBUG
+ else {
+ fprintf(stderr, "read-tree: warning #16 detected\n");
+ show_stage_entry(stderr, "head ", stages[head_match]);
+ show_stage_entry(stderr, "remote ", stages[remote_match]);
+ }
+#endif
+ if (head) { count += keep_entry(head); }
+ if (remote) { count += keep_entry(remote); }
+ return count;
+}
- /*
- * If we had an old entry that we now effectively
- * overwrite, make sure it wasn't dirty.
- */
- CHECK_OLD(ce);
- *dst++ = ce;
- src++;
- nr--;
+/*
+ * Two-way merge.
+ *
+ * The rule is to "carry forward" what is in the index without losing
+ * information across a "fast forward", favoring a successful merge
+ * over a merge failure when it makes sense. For details of the
+ * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
+ *
+ */
+static int twoway_merge(struct cache_entry **src)
+{
+ struct cache_entry *current = src[0];
+ struct cache_entry *oldtree = src[1], *newtree = src[2];
+
+ if (merge_size != 2)
+ return error("Cannot do a twoway merge of %d trees\n",
+ merge_size);
+
+ if (current) {
+ if ((!oldtree && !newtree) || /* 4 and 5 */
+ (!oldtree && newtree &&
+ same(current, newtree)) || /* 6 and 7 */
+ (oldtree && newtree &&
+ same(oldtree, newtree)) || /* 14 and 15 */
+ (oldtree && newtree &&
+ !same(oldtree, newtree) && /* 18 and 19*/
+ same(current, newtree))) {
+ return keep_entry(current);
+ }
+ else if (oldtree && !newtree && same(current, oldtree)) {
+ /* 10 or 11 */
+ return deleted_entry(oldtree, current);
+ }
+ else if (oldtree && newtree &&
+ same(current, oldtree) && !same(current, newtree)) {
+ /* 20 or 21 */
+ return merged_entry(newtree, current);
+ }
+ else {
+ /* all other failures */
+ if (oldtree)
+ reject_merge(oldtree);
+ if (current)
+ reject_merge(current);
+ if (newtree)
+ reject_merge(newtree);
+ return -1;
+ }
}
- if (old)
- reject_merge(old);
+ else if (newtree)
+ return merged_entry(newtree, current);
+ else
+ return deleted_entry(oldtree, current);
}
-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)
{
- static struct cache_entry null_entry;
- struct cache_entry **dst = src;
- struct cache_entry *old = &null_entry;
+ struct cache_entry *old = src[0];
+ struct cache_entry *a = src[1];
- while (nr) {
- struct cache_entry *ce;
+ if (merge_size != 1)
+ return error("Cannot do a oneway merge of %d trees\n",
+ merge_size);
+
+ if (!a)
+ return 0;
+ if (old && same(old, a)) {
+ return keep_entry(old);
+ }
+ return merged_entry(a, NULL);
+}
- ce = src[0];
+static int read_cache_unmerged(void)
+{
+ int i, deleted;
+ struct cache_entry **dst;
- /* We throw away original cache entries except for the stat information */
- if (!ce_stage(ce)) {
- old = ce;
- src++;
- nr--;
- active_nr--;
+ read_cache();
+ dst = active_cache;
+ deleted = 0;
+ for (i = 0; i < active_nr; i++) {
+ struct cache_entry *ce = active_cache[i];
+ if (ce_stage(ce)) {
+ deleted++;
continue;
}
- if (path_matches(ce, old) && same(ce, old))
- *ce = *old;
- ce->ce_flags &= ~htons(CE_STAGEMASK);
- *dst++ = ce;
- src++;
- nr--;
+ if (deleted)
+ *dst = ce;
+ dst++;
}
+ active_nr -= deleted;
+ return deleted;
}
-static char *read_tree_usage = "git-read-tree (<sha> | -m <sha1> [<sha2> <sha3>])";
+static const char read_tree_usage[] = "git-read-tree (<sha> | -m [-u | -i] <sha1> [<sha2> [<sha3>]])";
+
+static struct cache_file cache_file;
int main(int argc, char **argv)
{
- int i, newfd, merge;
+ int i, newfd, reset, stage = 0;
unsigned char sha1[20];
- static char lockfile[MAXPATHLEN+1];
- const char *indexfile = get_index_file();
+ merge_fn_t fn = NULL;
- snprintf(lockfile, sizeof(lockfile), "%s.lock", indexfile);
-
- newfd = open(lockfile, O_RDWR | O_CREAT | O_EXCL, 0600);
+ newfd = hold_index_file_for_update(&cache_file, get_index_file());
if (newfd < 0)
die("unable to create new cachefile");
- atexit(remove_lock_file);
- lockfile_name = lockfile;
merge = 0;
+ reset = 0;
for (i = 1; i < argc; i++) {
const char *arg = argv[i];
+ /* "-u" means "update", meaning that a merge will update
+ * the working tree.
+ */
+ if (!strcmp(arg, "-u")) {
+ update = 1;
+ continue;
+ }
+
+ /* "-i" means "index only", meaning that a merge will
+ * not even look at the working tree.
+ */
+ if (!strcmp(arg, "-i")) {
+ index_only = 1;
+ continue;
+ }
+
+ /* This differs from "-m" in that we'll silently ignore unmerged entries */
+ if (!strcmp(arg, "--reset")) {
+ if (stage || merge)
+ usage(read_tree_usage);
+ reset = 1;
+ merge = 1;
+ stage = 1;
+ read_cache_unmerged();
+ continue;
+ }
+
+ if (!strcmp(arg, "--trivial")) {
+ trivial_merges_only = 1;
+ continue;
+ }
+
/* "-m" stands for "merge", meaning we start in stage 1 */
if (!strcmp(arg, "-m")) {
- int i;
- if (stage)
- die("-m needs to come first");
- read_cache();
- for (i = 0; i < active_nr; i++) {
- if (ce_stage(active_cache[i]))
- die("you need to resolve your current index first");
- }
+ if (stage || merge)
+ usage(read_tree_usage);
+ if (read_cache_unmerged())
+ die("you need to resolve your current index first");
stage = 1;
merge = 1;
continue;
}
- if (get_sha1(arg, sha1) < 0)
+
+ /* using -u and -i at the same time makes no sense */
+ if (1 < index_only + update)
usage(read_tree_usage);
- if (stage > 3)
+
+ if (get_sha1(arg, sha1) < 0)
usage(read_tree_usage);
- if (unpack_tree(sha1) < 0)
+ if (list_tree(sha1) < 0)
die("failed to unpack tree object %s", arg);
stage++;
}
+ if ((update||index_only) && !merge)
+ usage(read_tree_usage);
+
if (merge) {
- switch (stage) {
- case 4: /* Three-way merge */
- trivially_merge_cache(active_cache, active_nr);
+ if (stage < 2)
+ die("just how do you expect me to merge %d trees?", stage-1);
+ switch (stage - 1) {
+ case 1:
+ fn = oneway_merge;
break;
- case 2: /* Just read a tree, merge with old cache contents */
- merge_stat_info(active_cache, active_nr);
+ case 2:
+ fn = twoway_merge;
+ break;
+ case 3:
+ fn = threeway_merge;
break;
default:
- die("just how do you expect me to merge %d trees?", stage-1);
+ fn = threeway_merge;
+ break;
}
+
+ if (stage - 1 >= 3)
+ head_idx = stage - 2;
+ else
+ head_idx = 1;
}
- if (write_cache(newfd, active_cache, active_nr) || rename(lockfile, indexfile))
+
+ unpack_trees(fn);
+ if (write_cache(newfd, active_cache, active_nr) ||
+ commit_index_file(&cache_file))
die("unable to write new index file");
- lockfile_name = NULL;
return 0;
}