*/
#include "cache.h"
-static void create_directories(const char *path)
+static int stage = 0;
+
+static int unpack_tree(unsigned char *sha1)
{
- int len = strlen(path);
- char *buf = malloc(len + 1);
- const char *slash = path;
-
- while ((slash = strchr(slash+1, '/')) != NULL) {
- len = slash - path;
- memcpy(buf, path, len);
- buf[len] = 0;
- mkdir(buf, 0700);
- }
+ void *buffer;
+ unsigned long size;
+
+ buffer = read_object_with_reference(sha1, "tree", &size, 0);
+ if (!buffer)
+ return -1;
+ return read_tree(buffer, size, stage);
+}
+
+static char *lockfile_name;
+
+static void remove_lock_file(void)
+{
+ if (lockfile_name)
+ unlink(lockfile_name);
+}
+
+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 int create_file(const char *path)
+static void trivially_merge_cache(struct cache_entry **src, int nr)
{
- int fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, 0600);
- if (fd < 0) {
- if (errno == ENOENT) {
- create_directories(path);
- fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, 0600);
+ 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--;
}
- return fd;
}
-static int unpack(unsigned char *sha1)
+static void merge_stat_info(struct cache_entry **src, int nr)
{
- void *buffer;
- unsigned long size;
- char type[20];
+ static struct cache_entry null_entry;
+ struct cache_entry **dst = src;
+ struct cache_entry *old = &null_entry;
- buffer = read_sha1_file(sha1, type, &size);
- if (!buffer)
- usage("unable to read sha1 file");
- if (strcmp(type, "tree"))
- usage("expected a 'tree' node");
- while (size) {
- int len = strlen(buffer)+1;
- unsigned char *sha1 = buffer + len;
- char *path = strchr(buffer, ' ')+1;
- char *data;
- unsigned long filesize;
- unsigned int mode;
- int fd;
-
- if (size < len + 20 || sscanf(buffer, "%o", &mode) != 1)
- usage("corrupt 'tree' file");
- buffer = sha1 + 20;
- size -= len + 20;
- data = read_sha1_file(sha1, type, &filesize);
- if (!data || strcmp(type, "blob"))
- usage("tree file refers to bad file data");
- fd = create_file(path);
- if (fd < 0)
- usage("unable to create file");
- if (write(fd, data, filesize) != filesize)
- usage("unable to write file");
- fchmod(fd, mode);
- close(fd);
- free(data);
+ 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--;
}
- return 0;
}
+static char *read_tree_usage = "read-tree (<sha> | -m <sha1> [<sha2> <sha3>])";
+
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);
+ if (newfd < 0)
+ die("unable to create new cachefile");
+ atexit(remove_lock_file);
+ lockfile_name = lockfile;
- if (argc != 2)
- usage("read-tree <key>");
- if (get_sha1_hex(argv[1], sha1) < 0)
- usage("read-tree <key>");
- sha1_file_directory = getenv(DB_ENVIRONMENT);
- if (!sha1_file_directory)
- sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
- if (unpack(sha1) < 0)
- usage("unpack failed");
+ merge = 0;
+ for (i = 1; i < argc; i++) {
+ const char *arg = argv[i];
+
+ /* "-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");
+ }
+ stage = 1;
+ merge = 1;
+ continue;
+ }
+ if (get_sha1_hex(arg, sha1) < 0)
+ usage(read_tree_usage);
+ if (stage > 3)
+ usage(read_tree_usage);
+ if (unpack_tree(sha1) < 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(lockfile, indexfile))
+ die("unable to write new index file");
+ lockfile_name = NULL;
return 0;
}