#include "cache.h"
+#include "tree-walk.h"
+#include "xdiff-interface.h"
+#include "blob.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;
+
+struct merge_list {
+ struct merge_list *next;
+ struct merge_list *link; /* other stages for this object */
+
+ unsigned int stage : 2,
+ flags : 30;
+ unsigned int mode;
+ const char *path;
+ struct blob *blob;
};
-static struct tree_entry *read_tree(unsigned char *sha1)
+static struct merge_list *merge_result, **merge_result_end = &merge_result;
+
+static void add_merge_entry(struct merge_list *entry)
{
- 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;
+ *merge_result_end = entry;
+ merge_result_end = &entry->next;
+}
+
+static void merge_trees(struct tree_desc t[3], const char *base);
+
+static const char *explanation(struct merge_list *entry)
+{
+ switch (entry->stage) {
+ case 0:
+ return "merged";
+ case 3:
+ return "added in remote";
+ case 2:
+ if (entry->link)
+ return "added in both";
+ return "added in local";
}
- return ret;
+
+ /* Existed in base */
+ entry = entry->link;
+ if (!entry)
+ return "removed in both";
+
+ if (entry->link)
+ return "changed in both";
+
+ if (entry->stage == 3)
+ return "removed in local";
+ return "removed in remote";
}
-static void show(const struct tree_entry *a, const char *path)
+extern void *merge_file(struct blob *, struct blob *, struct blob *, unsigned long *);
+
+static void *result(struct merge_list *entry, unsigned long *size)
{
- printf("select %o %s %s%c", a->mode, sha1_to_hex(a->sha1), path, 0);
+ enum object_type type;
+ struct blob *base, *our, *their;
+
+ if (!entry->stage)
+ return read_sha1_file(entry->blob->object.sha1, &type, size);
+ base = NULL;
+ if (entry->stage == 1) {
+ base = entry->blob;
+ entry = entry->link;
+ }
+ our = NULL;
+ if (entry && entry->stage == 2) {
+ our = entry->blob;
+ entry = entry->link;
+ }
+ their = NULL;
+ if (entry)
+ their = entry->blob;
+ return merge_file(base, our, their, size);
}
-static void merge(const struct tree_entry *a, const struct tree_entry *b, const struct tree_entry *c, const char *path)
+static void *origin(struct merge_list *entry, unsigned long *size)
{
- 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);
+ enum object_type type;
+ while (entry) {
+ if (entry->stage == 2)
+ return read_sha1_file(entry->blob->object.sha1, &type, size);
+ entry = entry->link;
+ }
+ return NULL;
}
-static int same(const struct tree_entry *a, const struct tree_entry *b)
+static int show_outf(void *priv_, mmbuffer_t *mb, int nbuf)
{
- return a->mode == b->mode && !memcmp(a->sha1, b->sha1, 20);
+ int i;
+ for (i = 0; i < nbuf; i++)
+ printf("%.*s", (int) mb[i].size, mb[i].ptr);
+ return 0;
}
-static void merge_entry(const struct tree_entry *src, const struct tree_entry *dst1, const struct tree_entry *dst2)
+static void show_diff(struct merge_list *entry)
{
- 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;
+ unsigned long size;
+ mmfile_t src, dst;
+ xpparam_t xpp;
+ xdemitconf_t xecfg;
+ xdemitcb_t ecb;
- 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);
- return;
+ xpp.flags = XDF_NEED_MINIMAL;
+ memset(&xecfg, 0, sizeof(xecfg));
+ xecfg.ctxlen = 3;
+ ecb.outf = show_outf;
+ ecb.priv = NULL;
+
+ src.ptr = origin(entry, &size);
+ if (!src.ptr)
+ size = 0;
+ src.size = size;
+ dst.ptr = result(entry, &size);
+ if (!dst.ptr)
+ size = 0;
+ dst.size = size;
+ xdi_diff(&src, &dst, &xpp, &xecfg, &ecb);
+ free(src.ptr);
+ free(dst.ptr);
+}
+
+static void show_result_list(struct merge_list *entry)
+{
+ printf("%s\n", explanation(entry));
+ do {
+ struct merge_list *link = entry->link;
+ static const char *desc[4] = { "result", "base", "our", "their" };
+ printf(" %-6s %o %s %s\n", desc[entry->stage], entry->mode, sha1_to_hex(entry->blob->object.sha1), entry->path);
+ entry = link;
+ } while (entry);
+}
+
+static void show_result(void)
+{
+ struct merge_list *walk;
+
+ walk = merge_result;
+ while (walk) {
+ show_result_list(walk);
+ show_diff(walk);
+ walk = walk->next;
}
- if (same(a, b)) {
- show(c, 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 &&
+ !hashcmp(a->sha1, b->sha1) &&
+ a->mode == b->mode;
+}
+
+static struct merge_list *create_entry(unsigned stage, unsigned mode, const unsigned char *sha1, const char *path)
+{
+ struct merge_list *res = xmalloc(sizeof(*res));
+
+ memset(res, 0, sizeof(*res));
+ res->stage = stage;
+ res->path = path;
+ res->mode = mode;
+ res->blob = lookup_blob(sha1);
+ return res;
+}
+
+static void resolve(const char *base, struct name_entry *branch1, struct name_entry *result)
+{
+ struct merge_list *orig, *final;
+ const char *path;
+
+ /* If it's already branch1, don't bother showing it */
+ if (!branch1)
return;
+
+ path = xstrdup(mkpath("%s%s", base, result->path));
+ orig = create_entry(2, branch1->mode, branch1->sha1, path);
+ final = create_entry(0, result->mode, result->sha1, path);
+
+ final->link = orig;
+
+ add_merge_entry(final);
+}
+
+static int unresolved_directory(const char *base, struct name_entry n[3])
+{
+ int baselen, pathlen;
+ 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 (same(a, c)) {
- show(b, path);
+ if (!S_ISDIR(p->mode))
+ return 0;
+ baselen = strlen(base);
+ pathlen = tree_entry_len(p->path, p->sha1);
+ newbase = xmalloc(baselen + pathlen + 2);
+ memcpy(newbase, base, baselen);
+ memcpy(newbase + baselen, p->path, pathlen);
+ memcpy(newbase + baselen + 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 struct merge_list *link_entry(unsigned stage, const char *base, struct name_entry *n, struct merge_list *entry)
+{
+ const char *path;
+ struct merge_list *link;
+
+ if (!n->mode)
+ return entry;
+ if (entry)
+ path = entry->path;
+ else
+ path = xstrdup(mkpath("%s%s", base, n->path));
+ link = create_entry(stage, n->mode, n->sha1, path);
+ link->link = entry;
+ return link;
+}
+
+static void unresolved(const char *base, struct name_entry n[3])
+{
+ struct merge_list *entry = NULL;
+
+ if (unresolved_directory(base, n))
return;
- }
- merge(a, b, c, path);
+
+ /*
+ * Do them in reverse order so that the resulting link
+ * list has the stages in order - link_entry adds new
+ * links at the front.
+ */
+ entry = link_entry(3, base, n + 2, entry);
+ entry = link_entry(2, base, n + 1, entry);
+ entry = link_entry(1, base, n + 0, entry);
+
+ add_merge_entry(entry);
}
-/* For two entries, select the smaller one, clear the bigger one */
-static void smaller(struct tree_entry **ap, struct tree_entry **bp)
+/*
+ * 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)
{
- 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;
+ /* Same in both? */
+ if (same_entry(entry+1, entry+2)) {
+ if (entry[0].sha1) {
+ resolve(base, NULL, entry+1);
+ return;
}
}
-}
-static void merge_tree(struct tree_entry *src, struct tree_entry *dst1, struct tree_entry *dst2)
-{
- 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);
+ 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))
+ 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];
+ struct tree_desc t[3];
+ void *buf1, *buf2, *buf3;
+
+ if (argc != 4)
+ usage(merge_tree_usage);
+
+ setup_git_directory();
+
+ 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);
- 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));
+ show_result();
return 0;
}