X-Git-Url: https://git.octo.it/?a=blobdiff_plain;f=read-tree.c;h=fbd0da0ebdc5c523b7f35399a39a3b8efd373112;hb=8544a6f1b8e7340924c406d717ac37becd2f6046;hp=345d576dcbb16874ebae0cb868c0b416d20f5a3d;hpb=aba06682473e2d797011f966d66c93043e3ed57a;p=git.git

diff --git a/read-tree.c b/read-tree.c
index 345d576d..fbd0da0e 100644
--- a/read-tree.c
+++ b/read-tree.c
@@ -6,84 +6,20 @@
 #include "cache.h"
 
 static int stage = 0;
+static int update = 0;
 
-static int read_one_entry(unsigned char *sha1, const char *base, int baselen, const char *pathname, unsigned mode)
-{
-	int len = strlen(pathname);
-	unsigned int size = cache_entry_size(baselen + len);
-	struct cache_entry *ce = malloc(size);
-
-	memset(ce, 0, size);
-
-	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);
-	return add_cache_entry(ce, 1);
-}
-
-static int read_tree_recursive(void *buffer, unsigned long size,
-			       const char *base, int baselen)
-{
-	while (size) {
-		int len = strlen(buffer)+1;
-		unsigned char *sha1 = buffer + len;
-		char *path = strchr(buffer, ' ')+1;
-		unsigned int mode;
-
-		if (size < len + 20 || sscanf(buffer, "%o", &mode) != 1)
-			return -1;
-
-		buffer = sha1 + 20;
-		size -= len + 20;
-
-		if (S_ISDIR(mode)) {
-			int retval;
-			int pathlen = strlen(path);
-			char *newbase = malloc(baselen + 1 + pathlen);
-			void *eltbuf;
-			char elttype[20];
-			unsigned long eltsize;
-
-			eltbuf = read_sha1_file(sha1, elttype, &eltsize);
-			if (!eltbuf || strcmp(elttype, "tree"))
-				return -1;
-			memcpy(newbase, base, baselen);
-			memcpy(newbase + baselen, path, pathlen);
-			newbase[baselen + pathlen] = '/';
-			retval = read_tree_recursive(eltbuf, eltsize,
-						     newbase,
-						     baselen + pathlen + 1);
-			free(eltbuf);
-			free(newbase);
-			if (retval)
-				return -1;
-			continue;
-		}
-		if (read_one_entry(sha1, base, baselen, path, mode) < 0)
-			return -1;
-	}
-	return 0;
-}
-
-static int read_tree(unsigned char *sha1, const char *base, int baselen)
+static int unpack_tree(unsigned char *sha1)
 {
 	void *buffer;
 	unsigned long size;
+	int ret;
 
-	buffer = read_tree_with_tree_or_commit_sha1(sha1, &size, 0);
+	buffer = read_object_with_reference(sha1, "tree", &size, NULL);
 	if (!buffer)
 		return -1;
-	return read_tree_recursive(buffer, size, base, baselen);
-}
-
-static char *lockfile_name;
-
-static void remove_lock_file(void)
-{
-	if (lockfile_name)
-		unlink(lockfile_name);
+	ret = read_tree(buffer, size, stage);
+	free(buffer);
+	return ret;
 }
 
 static int path_matches(struct cache_entry *a, struct cache_entry *b)
@@ -103,27 +39,11 @@ static int same(struct cache_entry *a, struct cache_entry *b)
 /*
  * 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
@@ -141,102 +61,243 @@ static struct cache_entry *merge_entries(struct cache_entry *a,
 	 * 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;
 }
 
-static void trivially_merge_cache(struct cache_entry **src, int nr)
+/*
+ * When a CE gets turned into an unmerged entry, we
+ * want it to be up-to-date
+ */
+static void verify_uptodate(struct cache_entry *ce)
 {
-	static struct cache_entry null_entry;
-	struct cache_entry **dst = src;
-	struct cache_entry *old = &null_entry;
+	struct stat st;
 
-	while (nr) {
-		struct cache_entry *ce, *result;
+	if (!lstat(ce->name, &st)) {
+		unsigned changed = ce_match_stat(ce, &st);
+		if (!changed)
+			return;
+		errno = 0;
+	}
+	if (errno == ENOENT)
+		return;
+	die("Entry '%s' not uptodate. Cannot merge.", ce->name);
+}
 
-		ce = src[0];
+/*
+ * 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)
+{
+	die("Entry '%s' would be overwritten by merge. Cannot merge.", ce->name);
+}
 
-		/* We throw away original cache entries except for the stat information */
-		if (!ce_stage(ce)) {
-			old = ce;
-			src++;
-			nr--;
-			active_nr--;
-			continue;
+static int merged_entry(struct cache_entry *merge, struct cache_entry *old, struct cache_entry **dst)
+{
+	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);
+	*dst++ = merge;
+	return 1;
+}
+
+static int threeway_merge(struct cache_entry *stages[4], struct cache_entry **dst)
+{
+	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;
+	}
+	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;
+}
+
+/*
+ * 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 **dst)
+{
+	struct cache_entry *current = src[0];
+	struct cache_entry *oldtree = src[1], *newtree = src[2];
+
+	if (src[3])
+		return -1;
+
+	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))) {
+			*dst++ = current;
+			return 1;
+		}
+		else if (oldtree && !newtree && same(current, oldtree)) {
+			/* 10 or 11 */
+			verify_uptodate(current);
+			return 0;
 		}
-		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;
+		else if (oldtree && newtree &&
+			 same(current, oldtree) && !same(current, newtree)) {
+			/* 20 or 21 */
+			verify_uptodate(current);
+			return merged_entry(newtree, NULL, dst);
 		}
-		*dst++ = ce;
-		src++;
-		nr--;
+		else
+			/* all other failures */
+			return -1;
 	}
+	else if (newtree)
+		return merged_entry(newtree, NULL, dst);
+	else
+		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 *old = &null_entry;
+	struct cache_entry *old = src[0];
+	struct cache_entry *a = src[1];
 
-	while (nr) {
-		struct cache_entry *ce;
+	if (src[2] || src[3])
+		return -1;
 
-		ce = src[0];
+	if (!a)
+		return 0;
+	if (old && same(old, a)) {
+		*dst++ = old;
+		return 1;
+	}
+	return merged_entry(a, NULL, dst);
+}
 
-		/* We throw away original cache entries except for the stat information */
-		if (!ce_stage(ce)) {
-			old = ce;
-			src++;
-			nr--;
+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_flags & mask) {
+			ce->ce_flags &= ~mask;
+			if (update)
+				checkout_entry(ce, &state);
+		}
+	}
+}
+
+typedef int (*merge_fn_t)(struct cache_entry **, struct cache_entry **);
+
+static void merge_cache(struct cache_entry **src, int nr, merge_fn_t fn)
+{
+	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--;
-			continue;
+			if (!--nr)
+				break;
+			if (!path_matches(ce, name))
+				break;
 		}
-		if (path_matches(ce, old) && same(ce, old))
-			*ce = *old;
-		ce->ce_flags &= ~htons(CE_STAGEMASK);
-		*dst++ = ce;
-		src++;
-		nr--;
+
+		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 = "read-tree (<sha> | -m <sha1> [<sha2> <sha3>])";
+static char *read_tree_usage = "git-read-tree (<sha> | -m [-u] <sha1> [<sha2> [<sha3>]])";
+
+static struct cache_file cache_file;
 
 int main(int argc, char **argv)
 {
 	int i, newfd, merge;
 	unsigned char sha1[20];
-	static char lockfile[MAXPATHLEN+1];
-	const char *indexfile = get_index_file();
 
-	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;
 	for (i = 1; i < argc; i++) {
 		const char *arg = argv[i];
 
+		/* "-u" means "update", meaning that a merge will update the working directory */
+		if (!strcmp(arg, "-u")) {
+			update = 1;
+			continue;
+		}
+
 		/* "-m" stands for "merge", meaning we start in stage 1 */
 		if (!strcmp(arg, "-m")) {
 			int i;
@@ -251,28 +312,28 @@ int main(int argc, char **argv)
 			merge = 1;
 			continue;
 		}
-		if (get_sha1_hex(arg, sha1) < 0)
+		if (get_sha1(arg, sha1) < 0)
 			usage(read_tree_usage);
 		if (stage > 3)
 			usage(read_tree_usage);
-		if (read_tree(sha1, "", 0) < 0)
+		if (unpack_tree(sha1) < 0)
 			die("failed to unpack tree object %s", arg);
 		stage++;
 	}
+	if (update && !merge)
+		usage(read_tree_usage);
 	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:
+		static const merge_fn_t merge_function[] = {
+			[1] = oneway_merge,
+			[2] = twoway_merge,
+			[3] = threeway_merge,
+		};
+		if (stage < 2 || stage > 4)
 			die("just how do you expect me to merge %d trees?", stage-1);
-		}
+		merge_cache(active_cache, active_nr, merge_function[stage-1]);
 	}
-	if (write_cache(newfd, active_cache, active_nr) || rename(lockfile, indexfile))
+	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;
 }