#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(unsigned char *sha1, const char *base, int baselen)
+static int unpack_tree(unsigned char *sha1)
{
void *buffer;
unsigned long size;
- char type[20];
+ int ret;
- buffer = read_sha1_file(sha1, type, &size);
+ buffer = read_object_with_reference(sha1, "tree", &size, NULL);
if (!buffer)
return -1;
- if (strcmp(type, "tree"))
- return -1;
- 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);
- memcpy(newbase, base, baselen);
- memcpy(newbase + baselen, path, pathlen);
- newbase[baselen + pathlen] = '/';
- retval = read_tree(sha1, newbase, baselen + pathlen + 1);
- free(newbase);
- if (retval)
- return -1;
- continue;
- }
- if (read_one_entry(sha1, base, baselen, path, mode) < 0)
- return -1;
- }
- return 0;
+ ret = read_tree(buffer, size, stage);
+ free(buffer);
+ return ret;
}
-static int remove_lock = 0;
+static char *lockfile_name;
static void remove_lock_file(void)
{
- if (remove_lock)
- unlink(".git/index.lock");
+ 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 NULL;
}
+/*
+ * 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)
+{
+ struct stat st;
+
+ 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);
+}
+
+/*
+ * 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);
+}
+
+#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)
{
struct cache_entry **dst = src;
+ struct cache_entry *old = NULL;
- while (nr) {
+ while (nr--) {
struct cache_entry *ce, *result;
- ce = src[0];
- if (nr > 2 && (result = merge_entries(ce, src[1], src[2])) != NULL) {
+ 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;
}
- *dst = ce;
- src++;
- dst++;
- nr--;
+
+ /*
+ * If we had an old entry that we now effectively
+ * overwrite, make sure it wasn't dirty.
+ */
+ CHECK_OLD(ce);
+ *dst++ = ce;
+ }
+ if (old)
+ reject_merge(old);
+}
+
+/*
+ * 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)
+{
+ 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);
}
+ verify_uptodate(old);
}
+/*
+ * Two-way merge.
+ *
+ * The rule is:
+ * - every current entry has to match the old tree
+ * - 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)
+{
+ 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);
+
+ 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");
+ }
+
+ /*
+ * 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);
+ }
+}
+
+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 *stat = &null_entry;
+
+ while (nr--) {
+ struct cache_entry *ce = *src++;
+
+ /* 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;
+ }
+}
+
+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);
+ }
+ }
+}
+
+static char *read_tree_usage = "git-read-tree (<sha> | -m <sha1> [<sha2> [<sha3>]])";
+
int main(int argc, char **argv)
{
- int i, newfd;
+ int i, newfd, merge;
unsigned char sha1[20];
+ static char lockfile[MAXPATHLEN+1];
+ const char *indexfile = get_index_file();
- newfd = open(".git/index.lock", O_RDWR | O_CREAT | O_EXCL, 0600);
+ 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);
- remove_lock = 1;
+ 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;
+ 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 [-m] <sha1>");
+ if (get_sha1(arg, sha1) < 0)
+ usage(read_tree_usage);
if (stage > 3)
- usage("can't merge more than two trees");
- if (read_tree(sha1, "", 0) < 0)
+ usage(read_tree_usage);
+ if (unpack_tree(sha1) < 0)
die("failed to unpack tree object %s", arg);
stage++;
}
- if (stage == 4)
- trivially_merge_cache(active_cache, active_nr);
- if (write_cache(newfd, active_cache, active_nr) ||
- rename(".git/index.lock", ".git/index"))
+ if (merge) {
+ switch (stage) {
+ case 4: /* Three-way merge */
+ trivially_merge_cache(active_cache, active_nr);
+ check_updates(active_cache, active_nr);
+ break;
+ case 3: /* Update from one tree to another */
+ twoway_merge(active_cache, active_nr);
+ 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);
+ 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");
- remove_lock = 0;
+ lockfile_name = NULL;
return 0;
}
projects / git.git / blobdiff