[thirdparty/git.git] / builtin / merge-tree.c

#define USE_THE_INDEX_COMPATIBILITY_MACROS
#include "builtin.h"
#include "tree-walk.h"
#include "xdiff-interface.h"
#include "object-store.h"
#include "repository.h"
#include "blob.h"
#include "exec-cmd.h"
#include "merge-blobs.h"

static const char merge_tree_usage[] = "git merge-tree <base-tree> <branch1> <branch2>";

struct merge_list {
	struct merge_list *next;
	struct merge_list *link;	/* other stages for this object */

	unsigned int stage : 2;
	unsigned int mode;
	const char *path;
	struct blob *blob;
};

static struct merge_list *merge_result, **merge_result_end = &merge_result;

static void add_merge_entry(struct merge_list *entry)
{
	*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";
	}

	/* 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 *result(struct merge_list *entry, unsigned long *size)
{
	enum object_type type;
	struct blob *base, *our, *their;
	const char *path = entry->path;

	if (!entry->stage)
		return read_object_file(&entry->blob->object.oid, &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_blobs(the_repository->index, path,
			   base, our, their, size);
}

static void *origin(struct merge_list *entry, unsigned long *size)
{
	enum object_type type;
	while (entry) {
		if (entry->stage == 2)
			return read_object_file(&entry->blob->object.oid,
						&type, size);
		entry = entry->link;
	}
	return NULL;
}

static int show_outf(void *priv_, mmbuffer_t *mb, int nbuf)
{
	int i;
	for (i = 0; i < nbuf; i++)
		printf("%.*s", (int) mb[i].size, mb[i].ptr);
	return 0;
}

static void show_diff(struct merge_list *entry)
{
	unsigned long size;
	mmfile_t src, dst;
	xpparam_t xpp;
	xdemitconf_t xecfg;
	xdemitcb_t ecb;

	xpp.flags = 0;
	memset(&xecfg, 0, sizeof(xecfg));
	xecfg.ctxlen = 3;
	ecb.out_hunk = NULL;
	ecb.out_line = 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;
	if (xdi_diff(&src, &dst, &xpp, &xecfg, &ecb))
		die("unable to generate diff");
	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, oid_to_hex(&entry->blob->object.oid), 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;
	}
}

/* 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	!is_null_oid(&a->oid) &&
		!is_null_oid(&b->oid) &&
		oideq(&a->oid, &b->oid) &&
		a->mode == b->mode;
}

static int both_empty(struct name_entry *a, struct name_entry *b)
{
	return is_null_oid(&a->oid) && is_null_oid(&b->oid);
}

static struct merge_list *create_entry(unsigned stage, unsigned mode, const struct object_id *oid, const char *path)
{
	struct merge_list *res = xcalloc(1, sizeof(*res));

	res->stage = stage;
	res->path = path;
	res->mode = mode;
	res->blob = lookup_blob(the_repository, oid);
	return res;
}

static char *traverse_path(const struct traverse_info *info, const struct name_entry *n)
{
	struct strbuf buf = STRBUF_INIT;
	strbuf_make_traverse_path(&buf, info, n->path, n->pathlen);
	return strbuf_detach(&buf, NULL);
}

static void resolve(const struct traverse_info *info, struct name_entry *ours, struct name_entry *result)
{
	struct merge_list *orig, *final;
	const char *path;

	/* If it's already ours, don't bother showing it */
	if (!ours)
		return;

	path = traverse_path(info, result);
	orig = create_entry(2, ours->mode, &ours->oid, path);
	final = create_entry(0, result->mode, &result->oid, path);

	final->link = orig;

	add_merge_entry(final);
}

static void unresolved_directory(const struct traverse_info *info,
				 struct name_entry n[3])
{
	struct repository *r = the_repository;
	char *newbase;
	struct name_entry *p;
	struct tree_desc t[3];
	void *buf0, *buf1, *buf2;

	for (p = n; p < n + 3; p++) {
		if (p->mode && S_ISDIR(p->mode))
			break;
	}
	if (n + 3 <= p)
		return; /* there is no tree here */

	newbase = traverse_path(info, p);

#define ENTRY_OID(e) (((e)->mode && S_ISDIR((e)->mode)) ? &(e)->oid : NULL)
	buf0 = fill_tree_descriptor(r, t + 0, ENTRY_OID(n + 0));
	buf1 = fill_tree_descriptor(r, t + 1, ENTRY_OID(n + 1));
	buf2 = fill_tree_descriptor(r, t + 2, ENTRY_OID(n + 2));
#undef ENTRY_OID

	merge_trees(t, newbase);

	free(buf0);
	free(buf1);
	free(buf2);
	free(newbase);
}


static struct merge_list *link_entry(unsigned stage, const struct traverse_info *info, 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 = traverse_path(info, n);
	link = create_entry(stage, n->mode, &n->oid, path);
	link->link = entry;
	return link;
}

static void unresolved(const struct traverse_info *info, struct name_entry n[3])
{
	struct merge_list *entry = NULL;
	int i;
	unsigned dirmask = 0, mask = 0;

	for (i = 0; i < 3; i++) {
		mask |= (1 << i);
		/*
		 * Treat missing entries as directories so that we return
		 * after unresolved_directory has handled this.
		 */
		if (!n[i].mode || S_ISDIR(n[i].mode))
			dirmask |= (1 << i);
	}

	unresolved_directory(info, n);

	if (dirmask == mask)
		return;

	if (n[2].mode && !S_ISDIR(n[2].mode))
		entry = link_entry(3, info, n + 2, entry);
	if (n[1].mode && !S_ISDIR(n[1].mode))
		entry = link_entry(2, info, n + 1, entry);
	if (n[0].mode && !S_ISDIR(n[0].mode))
		entry = link_entry(1, info, n + 0, entry);

	add_merge_entry(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 int threeway_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *entry, struct traverse_info *info)
{
	/* Same in both? */
	if (same_entry(entry+1, entry+2) || both_empty(entry+1, entry+2)) {
		/* Modified, added or removed identically */
		resolve(info, NULL, entry+1);
		return mask;
	}

	if (same_entry(entry+0, entry+1)) {
		if (!is_null_oid(&entry[2].oid) && !S_ISDIR(entry[2].mode)) {
			/* We did not touch, they modified -- take theirs */
			resolve(info, entry+1, entry+2);
			return mask;
		}
		/*
		 * If we did not touch a directory but they made it
		 * into a file, we fall through and unresolved()
		 * recurses down.  Likewise for the opposite case.
		 */
	}

	if (same_entry(entry+0, entry+2) || both_empty(entry+0, entry+2)) {
		/* We added, modified or removed, they did not touch -- take ours */
		resolve(info, NULL, entry+1);
		return mask;
	}

	unresolved(info, entry);
	return mask;
}

static void merge_trees(struct tree_desc t[3], const char *base)
{
	struct traverse_info info;

	setup_traverse_info(&info, base);
	info.fn = threeway_callback;
	traverse_trees(&the_index, 3, t, &info);
}

static void *get_tree_descriptor(struct repository *r,
				 struct tree_desc *desc,
				 const char *rev)
{
	struct object_id oid;
	void *buf;

	if (repo_get_oid(r, rev, &oid))
		die("unknown rev %s", rev);
	buf = fill_tree_descriptor(r, desc, &oid);
	if (!buf)
		die("%s is not a tree", rev);
	return buf;
}

int cmd_merge_tree(int argc, const char **argv, const char *prefix)
{
	struct repository *r = the_repository;
	struct tree_desc t[3];
	void *buf1, *buf2, *buf3;

	if (argc != 4)
		usage(merge_tree_usage);

	buf1 = get_tree_descriptor(r, t+0, argv[1]);
	buf2 = get_tree_descriptor(r, t+1, argv[2]);
	buf3 = get_tree_descriptor(r, t+2, argv[3]);
	merge_trees(t, "");
	free(buf1);
	free(buf2);
	free(buf3);

	show_result();
	return 0;
}
Commit	Line	Data
f8adbec9	1	#define USE_THE_INDEX_COMPATIBILITY_MACROS
c2e86add	2	#include "builtin.h"
1b0c7174	3	#include "tree-walk.h"
0c799383	4	#include "xdiff-interface.h"
cbd53a21	5	#include "object-store.h"
da14a7ff	6	#include "repository.h"
83788070	7	#include "blob.h"
d807c4a0	8	#include "exec-cmd.h"
fa2364ec	9	#include "merge-blobs.h"
492e0759	10
34263de0	11	static const char merge_tree_usage[] = "git merge-tree <base-tree> <branch1> <branch2>";
492e0759	12
83788070 LT	13	struct merge_list {
	14	struct merge_list *next;
	15	struct merge_list link; / other stages for this object */
	16
b13112fa	17	unsigned int stage : 2;
83788070 LT	18	unsigned int mode;
	19	const char *path;
	20	struct blob *blob;
	21	};
	22
	23	static struct merge_list merge_result, *merge_result_end = &merge_result;
	24
	25	static void add_merge_entry(struct merge_list *entry)
	26	{
	27	*merge_result_end = entry;
	28	merge_result_end = &entry->next;
	29	}
	30
57065289	31	static void merge_trees(struct tree_desc t[3], const char *base);
492e0759	32
83788070 LT	33	static const char explanation(struct merge_list entry)
	34	{
	35	switch (entry->stage) {
	36	case 0:
	37	return "merged";
	38	case 3:
	39	return "added in remote";
	40	case 2:
	41	if (entry->link)
	42	return "added in both";
	43	return "added in local";
	44	}
	45
	46	/* Existed in base */
	47	entry = entry->link;
	48	if (!entry)
	49	return "removed in both";
	50
	51	if (entry->link)
	52	return "changed in both";
	53
	54	if (entry->stage == 3)
	55	return "removed in local";
	56	return "removed in remote";
	57	}
	58
0c799383 LT	59	static void result(struct merge_list entry, unsigned long *size)
0c799383 LT	60	{
21666f1a	61	enum object_type type;
0c799383	62	struct blob base, our, *their;
21baa6e0	63	const char *path = entry->path;
0c799383 LT	64
0c799383 LT	65	if (!entry->stage)
b4f5aca4	66	return read_object_file(&entry->blob->object.oid, &type, size);
0c799383 LT	67	base = NULL;
	68	if (entry->stage == 1) {
	69	base = entry->blob;
	70	entry = entry->link;
	71	}
	72	our = NULL;
	73	if (entry && entry->stage == 2) {
	74	our = entry->blob;
	75	entry = entry->link;
	76	}
	77	their = NULL;
	78	if (entry)
	79	their = entry->blob;
f8adbec9 NTND	80	return merge_blobs(the_repository->index, path,
f8adbec9 NTND	81	base, our, their, size);
0c799383 LT	82	}
	83
	84	static void origin(struct merge_list entry, unsigned long *size)
	85	{
21666f1a	86	enum object_type type;
0c799383 LT	87	while (entry) {
0c799383 LT	88	if (entry->stage == 2)
b4f5aca4	89	return read_object_file(&entry->blob->object.oid,
b4f5aca4	90	&type, size);
0c799383 LT	91	entry = entry->link;
	92	}
	93	return NULL;
	94	}
	95
	96	static int show_outf(void priv_, mmbuffer_t mb, int nbuf)
	97	{
	98	int i;
	99	for (i = 0; i < nbuf; i++)
	100	printf("%.*s", (int) mb[i].size, mb[i].ptr);
	101	return 0;
	102	}
	103
	104	static void show_diff(struct merge_list *entry)
	105	{
	106	unsigned long size;
	107	mmfile_t src, dst;
	108	xpparam_t xpp;
	109	xdemitconf_t xecfg;
	110	xdemitcb_t ecb;
	111
582aa00b	112	xpp.flags = 0;
30b25010	113	memset(&xecfg, 0, sizeof(xecfg));
0c799383	114	xecfg.ctxlen = 3;
611e42a5 JK	115	ecb.out_hunk = NULL;
611e42a5 JK	116	ecb.out_line = show_outf;
0c799383 LT	117	ecb.priv = NULL;
	118
	119	src.ptr = origin(entry, &size);
	120	if (!src.ptr)
	121	size = 0;
	122	src.size = size;
	123	dst.ptr = result(entry, &size);
	124	if (!dst.ptr)
	125	size = 0;
	126	dst.size = size;
3efb9880 JK	127	if (xdi_diff(&src, &dst, &xpp, &xecfg, &ecb))
3efb9880 JK	128	die("unable to generate diff");
0c799383 LT	129	free(src.ptr);
	130	free(dst.ptr);
	131	}
	132
83788070 LT	133	static void show_result_list(struct merge_list *entry)
	134	{
	135	printf("%s\n", explanation(entry));
	136	do {
	137	struct merge_list *link = entry->link;
	138	static const char *desc[4] = { "result", "base", "our", "their" };
f2fd0760	139	printf(" %-6s %o %s %s\n", desc[entry->stage], entry->mode, oid_to_hex(&entry->blob->object.oid), entry->path);
83788070 LT	140	entry = link;
	141	} while (entry);
	142	}
	143
	144	static void show_result(void)
	145	{
	146	struct merge_list *walk;
	147
	148	walk = merge_result;
	149	while (walk) {
	150	show_result_list(walk);
0c799383	151	show_diff(walk);
83788070 LT	152	walk = walk->next;
	153	}
	154	}
	155
492e0759 LT	156	/* An empty entry never compares same, not even to another empty entry */
	157	static int same_entry(struct name_entry a, struct name_entry b)
	158	{
ea82b2a0	159	return !is_null_oid(&a->oid) &&
	160	!is_null_oid(&b->oid) &&
	161	oideq(&a->oid, &b->oid) &&
492e0759 LT	162	a->mode == b->mode;
	163	}
	164
aacecc3b JK	165	static int both_empty(struct name_entry a, struct name_entry b)
aacecc3b JK	166	{
ea82b2a0	167	return is_null_oid(&a->oid) && is_null_oid(&b->oid);
aacecc3b JK	168	}
aacecc3b JK	169
3e930981	170	static struct merge_list create_entry(unsigned stage, unsigned mode, const struct object_id oid, const char *path)
492e0759	171	{
19d4b416	172	struct merge_list res = xcalloc(1, sizeof(res));
83788070	173
83788070 LT	174	res->stage = stage;
	175	res->path = path;
	176	res->mode = mode;
da14a7ff	177	res->blob = lookup_blob(the_repository, oid);
83788070	178	return res;
01df5297 LT	179	}
01df5297 LT	180
40d934df LT	181	static char traverse_path(const struct traverse_info info, const struct name_entry *n)
40d934df LT	182	{
c43ab062 JK	183	struct strbuf buf = STRBUF_INIT;
	184	strbuf_make_traverse_path(&buf, info, n->path, n->pathlen);
	185	return strbuf_detach(&buf, NULL);
40d934df LT	186	}
40d934df LT	187
8dd15c6a	188	static void resolve(const struct traverse_info info, struct name_entry ours, struct name_entry *result)
01df5297	189	{
83788070 LT	190	struct merge_list orig, final;
	191	const char *path;
	192
8dd15c6a JH	193	/* If it's already ours, don't bother showing it */
8dd15c6a JH	194	if (!ours)
01df5297	195	return;
01df5297	196
40d934df	197	path = traverse_path(info, result);
ea82b2a0	198	orig = create_entry(2, ours->mode, &ours->oid, path);
ea82b2a0	199	final = create_entry(0, result->mode, &result->oid, path);
83788070 LT	200
	201	final->link = orig;
	202
	203	add_merge_entry(final);
492e0759 LT	204	}
492e0759 LT	205
57065289 RS	206	static void unresolved_directory(const struct traverse_info *info,
57065289 RS	207	struct name_entry n[3])
492e0759	208	{
5e575807	209	struct repository *r = the_repository;
492e0759 LT	210	char *newbase;
	211	struct name_entry *p;
	212	struct tree_desc t[3];
	213	void buf0, buf1, *buf2;
	214
35ffe758 JH	215	for (p = n; p < n + 3; p++) {
	216	if (p->mode && S_ISDIR(p->mode))
	217	break;
492e0759	218	}
35ffe758 JH	219	if (n + 3 <= p)
35ffe758 JH	220	return; /* there is no tree here */
8dd15c6a	221
40d934df	222	newbase = traverse_path(info, p);
35ffe758	223
ea82b2a0	224	#define ENTRY_OID(e) (((e)->mode && S_ISDIR((e)->mode)) ? &(e)->oid : NULL)
5e575807 NTND	225	buf0 = fill_tree_descriptor(r, t + 0, ENTRY_OID(n + 0));
	226	buf1 = fill_tree_descriptor(r, t + 1, ENTRY_OID(n + 1));
	227	buf2 = fill_tree_descriptor(r, t + 2, ENTRY_OID(n + 2));
5c377d3d	228	#undef ENTRY_OID
35ffe758	229
57065289	230	merge_trees(t, newbase);
492e0759 LT	231
	232	free(buf0);
	233	free(buf1);
	234	free(buf2);
	235	free(newbase);
492e0759 LT	236	}
492e0759 LT	237
83788070	238
40d934df	239	static struct merge_list link_entry(unsigned stage, const struct traverse_info info, struct name_entry n, struct merge_list entry)
83788070 LT	240	{
	241	const char *path;
	242	struct merge_list *link;
	243
	244	if (!n->mode)
	245	return entry;
	246	if (entry)
	247	path = entry->path;
	248	else
40d934df	249	path = traverse_path(info, n);
ea82b2a0	250	link = create_entry(stage, n->mode, &n->oid, path);
83788070 LT	251	link->link = entry;
	252	return link;
	253	}
	254
40d934df	255	static void unresolved(const struct traverse_info *info, struct name_entry n[3])
492e0759	256	{
83788070	257	struct merge_list *entry = NULL;
35ffe758 JH	258	int i;
	259	unsigned dirmask = 0, mask = 0;
	260
	261	for (i = 0; i < 3; i++) {
187c00c6	262	mask \|= (1 << i);
94883b43 JK	263	/*
	264	* Treat missing entries as directories so that we return
	265	* after unresolved_directory has handled this.
	266	*/
	267	if (!n[i].mode \|\| S_ISDIR(n[i].mode))
35ffe758 JH	268	dirmask \|= (1 << i);
	269	}
	270
57065289	271	unresolved_directory(info, n);
83788070	272
35ffe758	273	if (dirmask == mask)
492e0759	274	return;
83788070	275
35ffe758 JH	276	if (n[2].mode && !S_ISDIR(n[2].mode))
	277	entry = link_entry(3, info, n + 2, entry);
	278	if (n[1].mode && !S_ISDIR(n[1].mode))
	279	entry = link_entry(2, info, n + 1, entry);
	280	if (n[0].mode && !S_ISDIR(n[0].mode))
	281	entry = link_entry(1, info, n + 0, entry);
83788070 LT	282
83788070 LT	283	add_merge_entry(entry);
492e0759 LT	284	}
492e0759 LT	285
164dcb97 LT	286	/*
	287	* Merge two trees together (t[1] and t[2]), using a common base (t[0])
	288	* as the origin.
	289	*
	290	* This walks the (sorted) trees in lock-step, checking every possible
	291	* name. Note that directories automatically sort differently from other
	292	* files (see "base_name_compare"), so you'll never see file/directory
	293	* conflicts, because they won't ever compare the same.
	294	*
	295	* IOW, if a directory changes to a filename, it will automatically be
	296	* seen as the directory going away, and the filename being created.
	297	*
	298	* Think of this as a three-way diff.
	299	*
	300	* The output will be either:
	301	* - successful merge
	302	* "0 mode sha1 filename"
	303	* NOTE NOTE NOTE! FIXME! We really really need to walk the index
	304	* in parallel with this too!
	305	*
	306	* - conflict:
	307	* "1 mode sha1 filename"
	308	* "2 mode sha1 filename"
	309	* "3 mode sha1 filename"
	310	* where not all of the 1/2/3 lines may exist, of course.
	311	*
	312	* The successful merge rules are the same as for the three-way merge
	313	* in git-read-tree.
	314	*/
91e4f036	315	static int threeway_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry entry, struct traverse_info info)
164dcb97 LT	316	{
164dcb97 LT	317	/* Same in both? */
ab5f4242	318	if (same_entry(entry+1, entry+2) \|\| both_empty(entry+1, entry+2)) {
aacecc3b JK	319	/* Modified, added or removed identically */
	320	resolve(info, NULL, entry+1);
	321	return mask;
164dcb97	322	}
492e0759	323
164dcb97	324	if (same_entry(entry+0, entry+1)) {
ea82b2a0	325	if (!is_null_oid(&entry[2].oid) && !S_ISDIR(entry[2].mode)) {
8dd15c6a	326	/* We did not touch, they modified -- take theirs */
40d934df	327	resolve(info, entry+1, entry+2);
5803c6f8	328	return mask;
492e0759	329	}
8dd15c6a JH	330	/*
	331	* If we did not touch a directory but they made it
	332	* into a file, we fall through and unresolved()
	333	* recurses down. Likewise for the opposite case.
	334	*/
164dcb97	335	}
492e0759	336
aacecc3b JK	337	if (same_entry(entry+0, entry+2) \|\| both_empty(entry+0, entry+2)) {
	338	/* We added, modified or removed, they did not touch -- take ours */
	339	resolve(info, NULL, entry+1);
	340	return mask;
492e0759	341	}
164dcb97	342
40d934df	343	unresolved(info, entry);
5803c6f8	344	return mask;
164dcb97 LT	345	}
164dcb97 LT	346
57065289	347	static void merge_trees(struct tree_desc t[3], const char *base)
164dcb97	348	{
40d934df LT	349	struct traverse_info info;
	350
	351	setup_traverse_info(&info, base);
	352	info.fn = threeway_callback;
67022e02	353	traverse_trees(&the_index, 3, t, &info);
492e0759 LT	354	}
492e0759 LT	355
5e575807 NTND	356	static void get_tree_descriptor(struct repository r,
	357	struct tree_desc *desc,
	358	const char *rev)
492e0759	359	{
d1a35e5c	360	struct object_id oid;
492e0759 LT	361	void *buf;
492e0759 LT	362
5e575807	363	if (repo_get_oid(r, rev, &oid))
492e0759	364	die("unknown rev %s", rev);
5e575807	365	buf = fill_tree_descriptor(r, desc, &oid);
492e0759 LT	366	if (!buf)
	367	die("%s is not a tree", rev);
	368	return buf;
	369	}
	370
907a7cb5	371	int cmd_merge_tree(int argc, const char *argv, const char prefix)
492e0759	372	{
5e575807	373	struct repository *r = the_repository;
492e0759 LT	374	struct tree_desc t[3];
	375	void buf1, buf2, *buf3;
	376
5b6df8e4	377	if (argc != 4)
492e0759 LT	378	usage(merge_tree_usage);
492e0759 LT	379
5e575807 NTND	380	buf1 = get_tree_descriptor(r, t+0, argv[1]);
	381	buf2 = get_tree_descriptor(r, t+1, argv[2]);
	382	buf3 = get_tree_descriptor(r, t+2, argv[3]);
492e0759 LT	383	merge_trees(t, "");
	384	free(buf1);
	385	free(buf2);
	386	free(buf3);
83788070 LT	387
83788070 LT	388	show_result();
492e0759 LT	389	return 0;
492e0759 LT	390	}