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

#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_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)
{
	char *path = xmallocz(traverse_path_len(info, n) + the_hash_algo->rawsz);
	return make_traverse_path(path, info, n);
}

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])
{
	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(t + 0, ENTRY_OID(n + 0));
	buf1 = fill_tree_descriptor(t + 1, ENTRY_OID(n + 1));
	buf2 = fill_tree_descriptor(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 tree_desc *desc, const char *rev)
{
	struct object_id oid;
	void *buf;

	if (get_oid(rev, &oid))
		die("unknown rev %s", rev);
	buf = fill_tree_descriptor(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 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);

	show_result();
	return 0;
}
Commit	Line	Data
c2e86add	1	#include "builtin.h"
1b0c7174	2	#include "tree-walk.h"
0c799383	3	#include "xdiff-interface.h"
cbd53a21	4	#include "object-store.h"
da14a7ff	5	#include "repository.h"
83788070	6	#include "blob.h"
d807c4a0	7	#include "exec-cmd.h"
fa2364ec	8	#include "merge-blobs.h"
492e0759	9
34263de0	10	static const char merge_tree_usage[] = "git merge-tree <base-tree> <branch1> <branch2>";
492e0759	11
83788070 LT	12	struct merge_list {
	13	struct merge_list *next;
	14	struct merge_list link; / other stages for this object */
	15
b13112fa	16	unsigned int stage : 2;
83788070 LT	17	unsigned int mode;
	18	const char *path;
	19	struct blob *blob;
	20	};
	21
	22	static struct merge_list merge_result, *merge_result_end = &merge_result;
	23
	24	static void add_merge_entry(struct merge_list *entry)
	25	{
	26	*merge_result_end = entry;
	27	merge_result_end = &entry->next;
	28	}
	29
57065289	30	static void merge_trees(struct tree_desc t[3], const char *base);
492e0759	31
83788070 LT	32	static const char explanation(struct merge_list entry)
	33	{
	34	switch (entry->stage) {
	35	case 0:
	36	return "merged";
	37	case 3:
	38	return "added in remote";
	39	case 2:
	40	if (entry->link)
	41	return "added in both";
	42	return "added in local";
	43	}
	44
	45	/* Existed in base */
	46	entry = entry->link;
	47	if (!entry)
	48	return "removed in both";
	49
	50	if (entry->link)
	51	return "changed in both";
	52
	53	if (entry->stage == 3)
	54	return "removed in local";
	55	return "removed in remote";
	56	}
	57
0c799383 LT	58	static void result(struct merge_list entry, unsigned long *size)
0c799383 LT	59	{
21666f1a	60	enum object_type type;
0c799383	61	struct blob base, our, *their;
21baa6e0	62	const char *path = entry->path;
0c799383 LT	63
0c799383 LT	64	if (!entry->stage)
b4f5aca4	65	return read_object_file(&entry->blob->object.oid, &type, size);
0c799383 LT	66	base = NULL;
	67	if (entry->stage == 1) {
	68	base = entry->blob;
	69	entry = entry->link;
	70	}
	71	our = NULL;
	72	if (entry && entry->stage == 2) {
	73	our = entry->blob;
	74	entry = entry->link;
	75	}
	76	their = NULL;
	77	if (entry)
	78	their = entry->blob;
f4a55b27	79	return merge_blobs(&the_index, path, base, our, their, size);
0c799383 LT	80	}
	81
	82	static void origin(struct merge_list entry, unsigned long *size)
	83	{
21666f1a	84	enum object_type type;
0c799383 LT	85	while (entry) {
0c799383 LT	86	if (entry->stage == 2)
b4f5aca4	87	return read_object_file(&entry->blob->object.oid,
b4f5aca4	88	&type, size);
0c799383 LT	89	entry = entry->link;
	90	}
	91	return NULL;
	92	}
	93
	94	static int show_outf(void priv_, mmbuffer_t mb, int nbuf)
	95	{
	96	int i;
	97	for (i = 0; i < nbuf; i++)
	98	printf("%.*s", (int) mb[i].size, mb[i].ptr);
	99	return 0;
	100	}
	101
	102	static void show_diff(struct merge_list *entry)
	103	{
	104	unsigned long size;
	105	mmfile_t src, dst;
	106	xpparam_t xpp;
	107	xdemitconf_t xecfg;
	108	xdemitcb_t ecb;
	109
582aa00b	110	xpp.flags = 0;
30b25010	111	memset(&xecfg, 0, sizeof(xecfg));
0c799383	112	xecfg.ctxlen = 3;
611e42a5 JK	113	ecb.out_hunk = NULL;
611e42a5 JK	114	ecb.out_line = show_outf;
0c799383 LT	115	ecb.priv = NULL;
	116
	117	src.ptr = origin(entry, &size);
	118	if (!src.ptr)
	119	size = 0;
	120	src.size = size;
	121	dst.ptr = result(entry, &size);
	122	if (!dst.ptr)
	123	size = 0;
	124	dst.size = size;
3efb9880 JK	125	if (xdi_diff(&src, &dst, &xpp, &xecfg, &ecb))
3efb9880 JK	126	die("unable to generate diff");
0c799383 LT	127	free(src.ptr);
	128	free(dst.ptr);
	129	}
	130
83788070 LT	131	static void show_result_list(struct merge_list *entry)
	132	{
	133	printf("%s\n", explanation(entry));
	134	do {
	135	struct merge_list *link = entry->link;
	136	static const char *desc[4] = { "result", "base", "our", "their" };
f2fd0760	137	printf(" %-6s %o %s %s\n", desc[entry->stage], entry->mode, oid_to_hex(&entry->blob->object.oid), entry->path);
83788070 LT	138	entry = link;
	139	} while (entry);
	140	}
	141
	142	static void show_result(void)
	143	{
	144	struct merge_list *walk;
	145
	146	walk = merge_result;
	147	while (walk) {
	148	show_result_list(walk);
0c799383	149	show_diff(walk);
83788070 LT	150	walk = walk->next;
	151	}
	152	}
	153
492e0759 LT	154	/* An empty entry never compares same, not even to another empty entry */
	155	static int same_entry(struct name_entry a, struct name_entry b)
	156	{
ea82b2a0	157	return !is_null_oid(&a->oid) &&
	158	!is_null_oid(&b->oid) &&
	159	oideq(&a->oid, &b->oid) &&
492e0759 LT	160	a->mode == b->mode;
	161	}
	162
aacecc3b JK	163	static int both_empty(struct name_entry a, struct name_entry b)
aacecc3b JK	164	{
ea82b2a0	165	return is_null_oid(&a->oid) && is_null_oid(&b->oid);
aacecc3b JK	166	}
aacecc3b JK	167
3e930981	168	static struct merge_list create_entry(unsigned stage, unsigned mode, const struct object_id oid, const char *path)
492e0759	169	{
19d4b416	170	struct merge_list res = xcalloc(1, sizeof(res));
83788070	171
83788070 LT	172	res->stage = stage;
	173	res->path = path;
	174	res->mode = mode;
da14a7ff	175	res->blob = lookup_blob(the_repository, oid);
83788070	176	return res;
01df5297 LT	177	}
01df5297 LT	178
40d934df LT	179	static char traverse_path(const struct traverse_info info, const struct name_entry *n)
40d934df LT	180	{
ea82b2a0	181	char *path = xmallocz(traverse_path_len(info, n) + the_hash_algo->rawsz);
40d934df LT	182	return make_traverse_path(path, info, n);
	183	}
	184
8dd15c6a	185	static void resolve(const struct traverse_info info, struct name_entry ours, struct name_entry *result)
01df5297	186	{
83788070 LT	187	struct merge_list orig, final;
	188	const char *path;
	189
8dd15c6a JH	190	/* If it's already ours, don't bother showing it */
8dd15c6a JH	191	if (!ours)
01df5297	192	return;
01df5297	193
40d934df	194	path = traverse_path(info, result);
ea82b2a0	195	orig = create_entry(2, ours->mode, &ours->oid, path);
ea82b2a0	196	final = create_entry(0, result->mode, &result->oid, path);
83788070 LT	197
	198	final->link = orig;
	199
	200	add_merge_entry(final);
492e0759 LT	201	}
492e0759 LT	202
57065289 RS	203	static void unresolved_directory(const struct traverse_info *info,
57065289 RS	204	struct name_entry n[3])
492e0759	205	{
492e0759 LT	206	char *newbase;
	207	struct name_entry *p;
	208	struct tree_desc t[3];
	209	void buf0, buf1, *buf2;
	210
35ffe758 JH	211	for (p = n; p < n + 3; p++) {
	212	if (p->mode && S_ISDIR(p->mode))
	213	break;
492e0759	214	}
35ffe758 JH	215	if (n + 3 <= p)
35ffe758 JH	216	return; /* there is no tree here */
8dd15c6a	217
40d934df	218	newbase = traverse_path(info, p);
35ffe758	219
ea82b2a0	220	#define ENTRY_OID(e) (((e)->mode && S_ISDIR((e)->mode)) ? &(e)->oid : NULL)
5c377d3d RS	221	buf0 = fill_tree_descriptor(t + 0, ENTRY_OID(n + 0));
	222	buf1 = fill_tree_descriptor(t + 1, ENTRY_OID(n + 1));
	223	buf2 = fill_tree_descriptor(t + 2, ENTRY_OID(n + 2));
	224	#undef ENTRY_OID
35ffe758	225
57065289	226	merge_trees(t, newbase);
492e0759 LT	227
	228	free(buf0);
	229	free(buf1);
	230	free(buf2);
	231	free(newbase);
492e0759 LT	232	}
492e0759 LT	233
83788070	234
40d934df	235	static struct merge_list link_entry(unsigned stage, const struct traverse_info info, struct name_entry n, struct merge_list entry)
83788070 LT	236	{
	237	const char *path;
	238	struct merge_list *link;
	239
	240	if (!n->mode)
	241	return entry;
	242	if (entry)
	243	path = entry->path;
	244	else
40d934df	245	path = traverse_path(info, n);
ea82b2a0	246	link = create_entry(stage, n->mode, &n->oid, path);
83788070 LT	247	link->link = entry;
	248	return link;
	249	}
	250
40d934df	251	static void unresolved(const struct traverse_info *info, struct name_entry n[3])
492e0759	252	{
83788070	253	struct merge_list *entry = NULL;
35ffe758 JH	254	int i;
	255	unsigned dirmask = 0, mask = 0;
	256
	257	for (i = 0; i < 3; i++) {
187c00c6	258	mask \|= (1 << i);
94883b43 JK	259	/*
	260	* Treat missing entries as directories so that we return
	261	* after unresolved_directory has handled this.
	262	*/
	263	if (!n[i].mode \|\| S_ISDIR(n[i].mode))
35ffe758 JH	264	dirmask \|= (1 << i);
	265	}
	266
57065289	267	unresolved_directory(info, n);
83788070	268
35ffe758	269	if (dirmask == mask)
492e0759	270	return;
83788070	271
35ffe758 JH	272	if (n[2].mode && !S_ISDIR(n[2].mode))
	273	entry = link_entry(3, info, n + 2, entry);
	274	if (n[1].mode && !S_ISDIR(n[1].mode))
	275	entry = link_entry(2, info, n + 1, entry);
	276	if (n[0].mode && !S_ISDIR(n[0].mode))
	277	entry = link_entry(1, info, n + 0, entry);
83788070 LT	278
83788070 LT	279	add_merge_entry(entry);
492e0759 LT	280	}
492e0759 LT	281
164dcb97 LT	282	/*
	283	* Merge two trees together (t[1] and t[2]), using a common base (t[0])
	284	* as the origin.
	285	*
	286	* This walks the (sorted) trees in lock-step, checking every possible
	287	* name. Note that directories automatically sort differently from other
	288	* files (see "base_name_compare"), so you'll never see file/directory
	289	* conflicts, because they won't ever compare the same.
	290	*
	291	* IOW, if a directory changes to a filename, it will automatically be
	292	* seen as the directory going away, and the filename being created.
	293	*
	294	* Think of this as a three-way diff.
	295	*
	296	* The output will be either:
	297	* - successful merge
	298	* "0 mode sha1 filename"
	299	* NOTE NOTE NOTE! FIXME! We really really need to walk the index
	300	* in parallel with this too!
	301	*
	302	* - conflict:
	303	* "1 mode sha1 filename"
	304	* "2 mode sha1 filename"
	305	* "3 mode sha1 filename"
	306	* where not all of the 1/2/3 lines may exist, of course.
	307	*
	308	* The successful merge rules are the same as for the three-way merge
	309	* in git-read-tree.
	310	*/
91e4f036	311	static int threeway_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry entry, struct traverse_info info)
164dcb97 LT	312	{
164dcb97 LT	313	/* Same in both? */
ab5f4242	314	if (same_entry(entry+1, entry+2) \|\| both_empty(entry+1, entry+2)) {
aacecc3b JK	315	/* Modified, added or removed identically */
	316	resolve(info, NULL, entry+1);
	317	return mask;
164dcb97	318	}
492e0759	319
164dcb97	320	if (same_entry(entry+0, entry+1)) {
ea82b2a0	321	if (!is_null_oid(&entry[2].oid) && !S_ISDIR(entry[2].mode)) {
8dd15c6a	322	/* We did not touch, they modified -- take theirs */
40d934df	323	resolve(info, entry+1, entry+2);
5803c6f8	324	return mask;
492e0759	325	}
8dd15c6a JH	326	/*
	327	* If we did not touch a directory but they made it
	328	* into a file, we fall through and unresolved()
	329	* recurses down. Likewise for the opposite case.
	330	*/
164dcb97	331	}
492e0759	332
aacecc3b JK	333	if (same_entry(entry+0, entry+2) \|\| both_empty(entry+0, entry+2)) {
	334	/* We added, modified or removed, they did not touch -- take ours */
	335	resolve(info, NULL, entry+1);
	336	return mask;
492e0759	337	}
164dcb97	338
40d934df	339	unresolved(info, entry);
5803c6f8	340	return mask;
164dcb97 LT	341	}
164dcb97 LT	342
57065289	343	static void merge_trees(struct tree_desc t[3], const char *base)
164dcb97	344	{
40d934df LT	345	struct traverse_info info;
	346
	347	setup_traverse_info(&info, base);
	348	info.fn = threeway_callback;
67022e02	349	traverse_trees(&the_index, 3, t, &info);
492e0759 LT	350	}
	351
	352	static void get_tree_descriptor(struct tree_desc desc, const char *rev)
	353	{
d1a35e5c	354	struct object_id oid;
492e0759 LT	355	void *buf;
492e0759 LT	356
d1a35e5c	357	if (get_oid(rev, &oid))
492e0759	358	die("unknown rev %s", rev);
5c377d3d	359	buf = fill_tree_descriptor(desc, &oid);
492e0759 LT	360	if (!buf)
	361	die("%s is not a tree", rev);
	362	return buf;
	363	}
	364
907a7cb5	365	int cmd_merge_tree(int argc, const char *argv, const char prefix)
492e0759 LT	366	{
	367	struct tree_desc t[3];
	368	void buf1, buf2, *buf3;
	369
5b6df8e4	370	if (argc != 4)
492e0759 LT	371	usage(merge_tree_usage);
	372
	373	buf1 = get_tree_descriptor(t+0, argv[1]);
	374	buf2 = get_tree_descriptor(t+1, argv[2]);
	375	buf3 = get_tree_descriptor(t+2, argv[3]);
	376	merge_trees(t, "");
	377	free(buf1);
	378	free(buf2);
	379	free(buf3);
83788070 LT	380
83788070 LT	381	show_result();
492e0759 LT	382	return 0;
492e0759 LT	383	}