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

#include "builtin.h"
#include "tree-walk.h"
#include "xdiff-interface.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(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.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;
	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	a->oid &&
		b->oid &&
		!oidcmp(a->oid, b->oid) &&
		a->mode == b->mode;
}

static int both_empty(struct name_entry *a, struct name_entry *b)
{
	return !(a->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(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));
	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 (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(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"
83788070	4	#include "blob.h"
d807c4a0	5	#include "exec-cmd.h"
fa2364ec	6	#include "merge-blobs.h"
492e0759	7
34263de0	8	static const char merge_tree_usage[] = "git merge-tree <base-tree> <branch1> <branch2>";
492e0759	9
83788070 LT	10	struct merge_list {
	11	struct merge_list *next;
	12	struct merge_list link; / other stages for this object */
	13
b13112fa	14	unsigned int stage : 2;
83788070 LT	15	unsigned int mode;
	16	const char *path;
	17	struct blob *blob;
	18	};
	19
	20	static struct merge_list merge_result, *merge_result_end = &merge_result;
	21
	22	static void add_merge_entry(struct merge_list *entry)
	23	{
	24	*merge_result_end = entry;
	25	merge_result_end = &entry->next;
	26	}
	27
57065289	28	static void merge_trees(struct tree_desc t[3], const char *base);
492e0759	29
83788070 LT	30	static const char explanation(struct merge_list entry)
	31	{
	32	switch (entry->stage) {
	33	case 0:
	34	return "merged";
	35	case 3:
	36	return "added in remote";
	37	case 2:
	38	if (entry->link)
	39	return "added in both";
	40	return "added in local";
	41	}
	42
	43	/* Existed in base */
	44	entry = entry->link;
	45	if (!entry)
	46	return "removed in both";
	47
	48	if (entry->link)
	49	return "changed in both";
	50
	51	if (entry->stage == 3)
	52	return "removed in local";
	53	return "removed in remote";
	54	}
	55
0c799383 LT	56	static void result(struct merge_list entry, unsigned long *size)
0c799383 LT	57	{
21666f1a	58	enum object_type type;
0c799383	59	struct blob base, our, *their;
21baa6e0	60	const char *path = entry->path;
0c799383 LT	61
0c799383 LT	62	if (!entry->stage)
b4f5aca4	63	return read_object_file(&entry->blob->object.oid, &type, size);
0c799383 LT	64	base = NULL;
	65	if (entry->stage == 1) {
	66	base = entry->blob;
	67	entry = entry->link;
	68	}
	69	our = NULL;
	70	if (entry && entry->stage == 2) {
	71	our = entry->blob;
	72	entry = entry->link;
	73	}
	74	their = NULL;
	75	if (entry)
	76	their = entry->blob;
fa2364ec	77	return merge_blobs(path, base, our, their, size);
0c799383 LT	78	}
	79
	80	static void origin(struct merge_list entry, unsigned long *size)
	81	{
21666f1a	82	enum object_type type;
0c799383 LT	83	while (entry) {
0c799383 LT	84	if (entry->stage == 2)
b4f5aca4	85	return read_object_file(&entry->blob->object.oid,
b4f5aca4	86	&type, size);
0c799383 LT	87	entry = entry->link;
	88	}
	89	return NULL;
	90	}
	91
	92	static int show_outf(void priv_, mmbuffer_t mb, int nbuf)
	93	{
	94	int i;
	95	for (i = 0; i < nbuf; i++)
	96	printf("%.*s", (int) mb[i].size, mb[i].ptr);
	97	return 0;
	98	}
	99
	100	static void show_diff(struct merge_list *entry)
	101	{
	102	unsigned long size;
	103	mmfile_t src, dst;
	104	xpparam_t xpp;
	105	xdemitconf_t xecfg;
	106	xdemitcb_t ecb;
	107
582aa00b	108	xpp.flags = 0;
30b25010	109	memset(&xecfg, 0, sizeof(xecfg));
0c799383	110	xecfg.ctxlen = 3;
0c799383 LT	111	ecb.outf = show_outf;
	112	ecb.priv = NULL;
	113
	114	src.ptr = origin(entry, &size);
	115	if (!src.ptr)
	116	size = 0;
	117	src.size = size;
	118	dst.ptr = result(entry, &size);
	119	if (!dst.ptr)
	120	size = 0;
	121	dst.size = size;
3efb9880 JK	122	if (xdi_diff(&src, &dst, &xpp, &xecfg, &ecb))
3efb9880 JK	123	die("unable to generate diff");
0c799383 LT	124	free(src.ptr);
	125	free(dst.ptr);
	126	}
	127
83788070 LT	128	static void show_result_list(struct merge_list *entry)
	129	{
	130	printf("%s\n", explanation(entry));
	131	do {
	132	struct merge_list *link = entry->link;
	133	static const char *desc[4] = { "result", "base", "our", "their" };
f2fd0760	134	printf(" %-6s %o %s %s\n", desc[entry->stage], entry->mode, oid_to_hex(&entry->blob->object.oid), entry->path);
83788070 LT	135	entry = link;
	136	} while (entry);
	137	}
	138
	139	static void show_result(void)
	140	{
	141	struct merge_list *walk;
	142
	143	walk = merge_result;
	144	while (walk) {
	145	show_result_list(walk);
0c799383	146	show_diff(walk);
83788070 LT	147	walk = walk->next;
	148	}
	149	}
	150
492e0759 LT	151	/* An empty entry never compares same, not even to another empty entry */
	152	static int same_entry(struct name_entry a, struct name_entry b)
	153	{
7d924c91	154	return a->oid &&
	155	b->oid &&
	156	!oidcmp(a->oid, b->oid) &&
492e0759 LT	157	a->mode == b->mode;
	158	}
	159
aacecc3b JK	160	static int both_empty(struct name_entry a, struct name_entry b)
aacecc3b JK	161	{
7d924c91	162	return !(a->oid \|\| b->oid);
aacecc3b JK	163	}
aacecc3b JK	164
3e930981	165	static struct merge_list create_entry(unsigned stage, unsigned mode, const struct object_id oid, const char *path)
492e0759	166	{
19d4b416	167	struct merge_list res = xcalloc(1, sizeof(res));
83788070	168
83788070 LT	169	res->stage = stage;
	170	res->path = path;
	171	res->mode = mode;
3aca1fc6	172	res->blob = lookup_blob(oid);
83788070	173	return res;
01df5297 LT	174	}
01df5297 LT	175
40d934df LT	176	static char traverse_path(const struct traverse_info info, const struct name_entry *n)
40d934df LT	177	{
3733e694	178	char *path = xmallocz(traverse_path_len(info, n));
40d934df LT	179	return make_traverse_path(path, info, n);
	180	}
	181
8dd15c6a	182	static void resolve(const struct traverse_info info, struct name_entry ours, struct name_entry *result)
01df5297	183	{
83788070 LT	184	struct merge_list orig, final;
	185	const char *path;
	186
8dd15c6a JH	187	/* If it's already ours, don't bother showing it */
8dd15c6a JH	188	if (!ours)
01df5297	189	return;
01df5297	190
40d934df	191	path = traverse_path(info, result);
3e930981	192	orig = create_entry(2, ours->mode, ours->oid, path);
3e930981	193	final = create_entry(0, result->mode, result->oid, path);
83788070 LT	194
	195	final->link = orig;
	196
	197	add_merge_entry(final);
492e0759 LT	198	}
492e0759 LT	199
57065289 RS	200	static void unresolved_directory(const struct traverse_info *info,
57065289 RS	201	struct name_entry n[3])
492e0759	202	{
492e0759 LT	203	char *newbase;
	204	struct name_entry *p;
	205	struct tree_desc t[3];
	206	void buf0, buf1, *buf2;
	207
35ffe758 JH	208	for (p = n; p < n + 3; p++) {
	209	if (p->mode && S_ISDIR(p->mode))
	210	break;
492e0759	211	}
35ffe758 JH	212	if (n + 3 <= p)
35ffe758 JH	213	return; /* there is no tree here */
8dd15c6a	214
40d934df	215	newbase = traverse_path(info, p);
35ffe758	216
5c377d3d RS	217	#define ENTRY_OID(e) (((e)->mode && S_ISDIR((e)->mode)) ? (e)->oid : NULL)
	218	buf0 = fill_tree_descriptor(t + 0, ENTRY_OID(n + 0));
	219	buf1 = fill_tree_descriptor(t + 1, ENTRY_OID(n + 1));
	220	buf2 = fill_tree_descriptor(t + 2, ENTRY_OID(n + 2));
	221	#undef ENTRY_OID
35ffe758	222
57065289	223	merge_trees(t, newbase);
492e0759 LT	224
	225	free(buf0);
	226	free(buf1);
	227	free(buf2);
	228	free(newbase);
492e0759 LT	229	}
492e0759 LT	230
83788070	231
40d934df	232	static struct merge_list link_entry(unsigned stage, const struct traverse_info info, struct name_entry n, struct merge_list entry)
83788070 LT	233	{
	234	const char *path;
	235	struct merge_list *link;
	236
	237	if (!n->mode)
	238	return entry;
	239	if (entry)
	240	path = entry->path;
	241	else
40d934df	242	path = traverse_path(info, n);
3e930981	243	link = create_entry(stage, n->mode, n->oid, path);
83788070 LT	244	link->link = entry;
	245	return link;
	246	}
	247
40d934df	248	static void unresolved(const struct traverse_info *info, struct name_entry n[3])
492e0759	249	{
83788070	250	struct merge_list *entry = NULL;
35ffe758 JH	251	int i;
	252	unsigned dirmask = 0, mask = 0;
	253
	254	for (i = 0; i < 3; i++) {
187c00c6	255	mask \|= (1 << i);
94883b43 JK	256	/*
	257	* Treat missing entries as directories so that we return
	258	* after unresolved_directory has handled this.
	259	*/
	260	if (!n[i].mode \|\| S_ISDIR(n[i].mode))
35ffe758 JH	261	dirmask \|= (1 << i);
	262	}
	263
57065289	264	unresolved_directory(info, n);
83788070	265
35ffe758	266	if (dirmask == mask)
492e0759	267	return;
83788070	268
35ffe758 JH	269	if (n[2].mode && !S_ISDIR(n[2].mode))
	270	entry = link_entry(3, info, n + 2, entry);
	271	if (n[1].mode && !S_ISDIR(n[1].mode))
	272	entry = link_entry(2, info, n + 1, entry);
	273	if (n[0].mode && !S_ISDIR(n[0].mode))
	274	entry = link_entry(1, info, n + 0, entry);
83788070 LT	275
83788070 LT	276	add_merge_entry(entry);
492e0759 LT	277	}
492e0759 LT	278
164dcb97 LT	279	/*
	280	* Merge two trees together (t[1] and t[2]), using a common base (t[0])
	281	* as the origin.
	282	*
	283	* This walks the (sorted) trees in lock-step, checking every possible
	284	* name. Note that directories automatically sort differently from other
	285	* files (see "base_name_compare"), so you'll never see file/directory
	286	* conflicts, because they won't ever compare the same.
	287	*
	288	* IOW, if a directory changes to a filename, it will automatically be
	289	* seen as the directory going away, and the filename being created.
	290	*
	291	* Think of this as a three-way diff.
	292	*
	293	* The output will be either:
	294	* - successful merge
	295	* "0 mode sha1 filename"
	296	* NOTE NOTE NOTE! FIXME! We really really need to walk the index
	297	* in parallel with this too!
	298	*
	299	* - conflict:
	300	* "1 mode sha1 filename"
	301	* "2 mode sha1 filename"
	302	* "3 mode sha1 filename"
	303	* where not all of the 1/2/3 lines may exist, of course.
	304	*
	305	* The successful merge rules are the same as for the three-way merge
	306	* in git-read-tree.
	307	*/
91e4f036	308	static int threeway_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry entry, struct traverse_info info)
164dcb97 LT	309	{
164dcb97 LT	310	/* Same in both? */
ab5f4242	311	if (same_entry(entry+1, entry+2) \|\| both_empty(entry+1, entry+2)) {
aacecc3b JK	312	/* Modified, added or removed identically */
	313	resolve(info, NULL, entry+1);
	314	return mask;
164dcb97	315	}
492e0759	316
164dcb97	317	if (same_entry(entry+0, entry+1)) {
7d924c91	318	if (entry[2].oid && !S_ISDIR(entry[2].mode)) {
8dd15c6a	319	/* We did not touch, they modified -- take theirs */
40d934df	320	resolve(info, entry+1, entry+2);
5803c6f8	321	return mask;
492e0759	322	}
8dd15c6a JH	323	/*
	324	* If we did not touch a directory but they made it
	325	* into a file, we fall through and unresolved()
	326	* recurses down. Likewise for the opposite case.
	327	*/
164dcb97	328	}
492e0759	329
aacecc3b JK	330	if (same_entry(entry+0, entry+2) \|\| both_empty(entry+0, entry+2)) {
	331	/* We added, modified or removed, they did not touch -- take ours */
	332	resolve(info, NULL, entry+1);
	333	return mask;
492e0759	334	}
164dcb97	335
40d934df	336	unresolved(info, entry);
5803c6f8	337	return mask;
164dcb97 LT	338	}
164dcb97 LT	339
57065289	340	static void merge_trees(struct tree_desc t[3], const char *base)
164dcb97	341	{
40d934df LT	342	struct traverse_info info;
	343
	344	setup_traverse_info(&info, base);
	345	info.fn = threeway_callback;
	346	traverse_trees(3, t, &info);
492e0759 LT	347	}
	348
	349	static void get_tree_descriptor(struct tree_desc desc, const char *rev)
	350	{
d1a35e5c	351	struct object_id oid;
492e0759 LT	352	void *buf;
492e0759 LT	353
d1a35e5c	354	if (get_oid(rev, &oid))
492e0759	355	die("unknown rev %s", rev);
5c377d3d	356	buf = fill_tree_descriptor(desc, &oid);
492e0759 LT	357	if (!buf)
	358	die("%s is not a tree", rev);
	359	return buf;
	360	}
	361
907a7cb5	362	int cmd_merge_tree(int argc, const char *argv, const char prefix)
492e0759 LT	363	{
	364	struct tree_desc t[3];
	365	void buf1, buf2, *buf3;
	366
5b6df8e4	367	if (argc != 4)
492e0759 LT	368	usage(merge_tree_usage);
	369
	370	buf1 = get_tree_descriptor(t+0, argv[1]);
	371	buf2 = get_tree_descriptor(t+1, argv[2]);
	372	buf3 = get_tree_descriptor(t+2, argv[3]);
	373	merge_trees(t, "");
	374	free(buf1);
	375	free(buf2);
	376	free(buf3);
83788070 LT	377
83788070 LT	378	show_result();
492e0759 LT	379	return 0;
492e0759 LT	380	}