#include "cache.h"
+#include "tree-walk.h"
-struct tree_entry {
- unsigned mode;
- unsigned char *sha1;
- char *path;
- struct tree_entry *next;
-};
+static const char merge_tree_usage[] = "git-merge-tree <base-tree> <branch1> <branch2>";
+static int resolve_directories = 1;
-static struct tree_entry *read_tree(unsigned char *sha1)
+static void merge_trees(struct tree_desc t[3], const char *base);
+
+/* An empty entry never compares same, not even to another empty entry */
+static int same_entry(struct name_entry *a, struct name_entry *b)
{
- char type[20];
- unsigned long size;
- void *buf = read_sha1_file(sha1, type, &size);
- struct tree_entry *ret = NULL, **tp = &ret;
-
- if (!buf || strcmp(type, "tree"))
- die("unable to read 'tree' object %s", sha1_to_hex(sha1));
- while (size) {
- int len = strlen(buf)+1;
- struct tree_entry * entry = malloc(sizeof(struct tree_entry));
- if (size < len + 20 || sscanf(buf, "%o", &entry->mode) != 1)
- die("corrupt 'tree' object %s", sha1_to_hex(sha1));
- entry->path = strchr(buf, ' ')+1;
- entry->sha1 = buf + len;
- entry->next = NULL;
- *tp = entry;
- tp = &entry->next;
- len += 20;
- buf += len;
- size -= len;
- }
- return ret;
+ return a->sha1 &&
+ b->sha1 &&
+ !memcmp(a->sha1, b->sha1, 20) &&
+ a->mode == b->mode;
}
-static void show(const struct tree_entry *a, const char *path)
+static const char *sha1_to_hex_zero(const unsigned char *sha1)
{
- printf("select %o %s %s%c", a->mode, sha1_to_hex(a->sha1), path, 0);
+ if (sha1)
+ return sha1_to_hex(sha1);
+ return "0000000000000000000000000000000000000000";
}
-static void merge(const struct tree_entry *a, const struct tree_entry *b, const struct tree_entry *c, const char *path)
+static void resolve(const char *base, struct name_entry *branch1, struct name_entry *result)
{
- char hex_a[60], hex_b[60], hex_c[60];
- strcpy(hex_a, sha1_to_hex(a->sha1));
- strcpy(hex_b, sha1_to_hex(b->sha1));
- strcpy(hex_c, sha1_to_hex(c->sha1));
- printf("merge %o->%o,%o %s->%s,%s %s%c",
- a->mode, b->mode, c->mode,
- hex_a, hex_b, hex_c, path, 0);
+ 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 same(const struct tree_entry *a, const struct tree_entry *b)
+static int unresolved_directory(const char *base, struct name_entry n[3])
{
- return a->mode == b->mode && !memcmp(a->sha1, b->sha1, 20);
+ 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 merge_entry(const struct tree_entry *src, const struct tree_entry *dst1, const struct tree_entry *dst2)
+static void unresolved(const char *base, struct name_entry n[3])
{
- static unsigned char nullsha1[20];
- static const struct tree_entry none = { 0, nullsha1, "", NULL };
- const char *path = NULL;
- const struct tree_entry *a, *b, *c;
-
- a = &none;
- b = &none;
- c = &none;
- if (src) { a = src; path = src->path; }
- if (dst1) { b = dst1; path = dst1->path; }
- if (dst2) { c = dst2; path = dst2->path; }
- if (same(b, c)) {
- show(b, path);
+ 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);
+}
+
+/*
+ * 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(a, b)) {
- show(c, path);
- 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(a, c)) {
- show(b, path);
- return;
+
+ if (same_entry(entry+0, entry+2)) {
+ if (entry[1].sha1 && !S_ISDIR(entry[1].mode)) {
+ resolve(base, NULL, entry+1);
+ return;
+ }
}
- merge(a, b, c, path);
+
+ unresolved(base, entry);
}
-/* For two entries, select the smaller one, clear the bigger one */
-static void smaller(struct tree_entry **ap, struct tree_entry **bp)
+static void merge_trees(struct tree_desc t[3], const char *base)
{
- struct tree_entry *a = *ap, *b = *bp;
- if (a && b) {
- int cmp = cache_name_compare(a->path, strlen(a->path), b->path, strlen(b->path));
- if (cmp) {
- if (cmp < 0)
- *bp = NULL;
- else
- *ap = NULL;
- }
- }
+ traverse_trees(3, t, base, threeway_callback);
}
-static void merge_tree(struct tree_entry *src, struct tree_entry *dst1, struct tree_entry *dst2)
+static void *get_tree_descriptor(struct tree_desc *desc, const char *rev)
{
- while (src || dst1 || dst2) {
- struct tree_entry *a, *b, *c;
- a = src;
- b = dst1;
- c = dst2;
- smaller(&a,&b);
- smaller(&a,&c);
- smaller(&b,&c);
- if (a) src = a->next;
- if (b) dst1 = b->next;
- if (c) dst2 = c->next;
- merge_entry(a,b,c);
- }
+ 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)
{
- unsigned char src[20], dst1[20], dst2[20];
-
- if (argc != 4 ||
- get_sha1_hex(argv[1], src) ||
- get_sha1_hex(argv[2], dst1) ||
- get_sha1_hex(argv[3], dst2))
- usage("merge-tree <src> <dst1> <dst2>");
- merge_tree(read_tree(src), read_tree(dst1), read_tree(dst2));
+ 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;
}