--- /dev/null
+#include "cache.h"
+#include "diff.h"
+
+static const char merge_tree_usage[] = "git-merge-tree <base-tree> <branch1> <branch2>";
+static int resolve_directories = 1;
+
+static void merge_trees(struct tree_desc t[3], const char *base);
+
+static void *fill_tree_descriptor(struct tree_desc *desc, const unsigned char *sha1)
+{
+ unsigned long size = 0;
+ void *buf = NULL;
+
+ if (sha1) {
+ buf = read_object_with_reference(sha1, "tree", &size, NULL);
+ if (!buf)
+ die("unable to read tree %s", sha1_to_hex(sha1));
+ }
+ desc->size = size;
+ desc->buf = buf;
+ return buf;
+}
+
+struct name_entry {
+ const unsigned char *sha1;
+ const char *path;
+ unsigned int mode;
+ int pathlen;
+};
+
+static void entry_clear(struct name_entry *a)
+{
+ memset(a, 0, sizeof(*a));
+}
+
+static int entry_compare(struct name_entry *a, struct name_entry *b)
+{
+ return base_name_compare(
+ a->path, a->pathlen, a->mode,
+ b->path, b->pathlen, b->mode);
+}
+
+static void entry_extract(struct tree_desc *t, struct name_entry *a)
+{
+ a->sha1 = tree_entry_extract(t, &a->path, &a->mode);
+ a->pathlen = strlen(a->path);
+}
+
+/* An empty entry never compares same, not even to another empty entry */
+static int same_entry(struct name_entry *a, struct name_entry *b)
+{
+ return a->sha1 &&
+ b->sha1 &&
+ !memcmp(a->sha1, b->sha1, 20) &&
+ a->mode == b->mode;
+}
+
+static const char *sha1_to_hex_zero(const unsigned char *sha1)
+{
+ if (sha1)
+ return sha1_to_hex(sha1);
+ return "0000000000000000000000000000000000000000";
+}
+
+static void resolve(const char *base, struct name_entry *branch1, struct name_entry *result)
+{
+ char branch1_sha1[50];
+
+ /* If it's already branch1, don't bother showing it */
+ if (!branch1)
+ return;
+ memcpy(branch1_sha1, sha1_to_hex_zero(branch1->sha1), 41);
+
+ printf("0 %06o->%06o %s->%s %s%s\n",
+ branch1->mode, result->mode,
+ branch1_sha1, sha1_to_hex_zero(result->sha1),
+ base, result->path);
+}
+
+static int unresolved_directory(const char *base, struct name_entry n[3])
+{
+ int baselen;
+ char *newbase;
+ struct name_entry *p;
+ struct tree_desc t[3];
+ void *buf0, *buf1, *buf2;
+
+ if (!resolve_directories)
+ return 0;
+ p = n;
+ if (!p->mode) {
+ p++;
+ if (!p->mode)
+ p++;
+ }
+ if (!S_ISDIR(p->mode))
+ return 0;
+ baselen = strlen(base);
+ newbase = xmalloc(baselen + p->pathlen + 2);
+ memcpy(newbase, base, baselen);
+ memcpy(newbase + baselen, p->path, p->pathlen);
+ memcpy(newbase + baselen + p->pathlen, "/", 2);
+
+ buf0 = fill_tree_descriptor(t+0, n[0].sha1);
+ buf1 = fill_tree_descriptor(t+1, n[1].sha1);
+ buf2 = fill_tree_descriptor(t+2, n[2].sha1);
+ merge_trees(t, newbase);
+
+ free(buf0);
+ free(buf1);
+ free(buf2);
+ free(newbase);
+ return 1;
+}
+
+static void unresolved(const char *base, struct name_entry n[3])
+{
+ if (unresolved_directory(base, n))
+ return;
+ if (n[0].sha1)
+ printf("1 %06o %s %s%s\n", n[0].mode, sha1_to_hex(n[0].sha1), base, n[0].path);
+ if (n[1].sha1)
+ printf("2 %06o %s %s%s\n", n[1].mode, sha1_to_hex(n[1].sha1), base, n[1].path);
+ if (n[2].sha1)
+ printf("3 %06o %s %s%s\n", n[2].mode, sha1_to_hex(n[2].sha1), base, n[2].path);
+}
+
+typedef void (*traverse_callback_t)(int n, unsigned long mask, struct name_entry *entry, const char *base);
+
+static void traverse_trees(int n, struct tree_desc *t, const char *base, traverse_callback_t callback)
+{
+ struct name_entry *entry = xmalloc(n*sizeof(*entry));
+
+ for (;;) {
+ struct name_entry entry[3];
+ unsigned long mask = 0;
+ int i, last;
+
+ last = -1;
+ for (i = 0; i < n; i++) {
+ if (!t[i].size)
+ continue;
+ entry_extract(t+i, entry+i);
+ if (last >= 0) {
+ int cmp = entry_compare(entry+i, entry+last);
+
+ /*
+ * Is the new name bigger than the old one?
+ * Ignore it
+ */
+ if (cmp > 0)
+ continue;
+ /*
+ * Is the new name smaller than the old one?
+ * Ignore all old ones
+ */
+ if (cmp < 0)
+ mask = 0;
+ }
+ mask |= 1ul << i;
+ last = i;
+ }
+ if (!mask)
+ break;
+
+ /*
+ * Update the tree entries we've walked, and clear
+ * all the unused name-entries.
+ */
+ for (i = 0; i < n; i++) {
+ if (mask & (1ul << i)) {
+ update_tree_entry(t+i);
+ continue;
+ }
+ entry_clear(entry + i);
+ }
+ callback(n, mask, entry, base);
+ }
+ free(entry);
+}
+
+/*
+ * Merge two trees together (t[1] and t[2]), using a common base (t[0])
+ * as the origin.
+ *
+ * This walks the (sorted) trees in lock-step, checking every possible
+ * name. Note that directories automatically sort differently from other
+ * files (see "base_name_compare"), so you'll never see file/directory
+ * conflicts, because they won't ever compare the same.
+ *
+ * IOW, if a directory changes to a filename, it will automatically be
+ * seen as the directory going away, and the filename being created.
+ *
+ * Think of this as a three-way diff.
+ *
+ * The output will be either:
+ * - successful merge
+ * "0 mode sha1 filename"
+ * NOTE NOTE NOTE! FIXME! We really really need to walk the index
+ * in parallel with this too!
+ *
+ * - conflict:
+ * "1 mode sha1 filename"
+ * "2 mode sha1 filename"
+ * "3 mode sha1 filename"
+ * where not all of the 1/2/3 lines may exist, of course.
+ *
+ * The successful merge rules are the same as for the three-way merge
+ * in git-read-tree.
+ */
+static void threeway_callback(int n, unsigned long mask, struct name_entry *entry, const char *base)
+{
+ /* Same in both? */
+ if (same_entry(entry+1, entry+2)) {
+ if (entry[0].sha1) {
+ resolve(base, NULL, entry+1);
+ return;
+ }
+ }
+
+ if (same_entry(entry+0, entry+1)) {
+ if (entry[2].sha1 && !S_ISDIR(entry[2].mode)) {
+ resolve(base, entry+1, entry+2);
+ return;
+ }
+ }
+
+ if (same_entry(entry+0, entry+2)) {
+ if (entry[1].sha1 && !S_ISDIR(entry[1].mode)) {
+ resolve(base, NULL, entry+1);
+ return;
+ }
+ }
+
+ unresolved(base, entry);
+}
+
+static void merge_trees(struct tree_desc t[3], const char *base)
+{
+ traverse_trees(3, t, base, threeway_callback);
+}
+
+static void *get_tree_descriptor(struct tree_desc *desc, const char *rev)
+{
+ unsigned char sha1[20];
+ void *buf;
+
+ if (get_sha1(rev, sha1) < 0)
+ die("unknown rev %s", rev);
+ buf = fill_tree_descriptor(desc, sha1);
+ if (!buf)
+ die("%s is not a tree", rev);
+ return buf;
+}
+
+int main(int argc, char **argv)
+{
+ struct tree_desc t[3];
+ void *buf1, *buf2, *buf3;
+
+ if (argc < 4)
+ usage(merge_tree_usage);
+
+ buf1 = get_tree_descriptor(t+0, argv[1]);
+ buf2 = get_tree_descriptor(t+1, argv[2]);
+ buf3 = get_tree_descriptor(t+2, argv[3]);
+ merge_trees(t, "");
+ free(buf1);
+ free(buf2);
+ free(buf3);
+ return 0;
+}
projects / git.git / commitdiff