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

#include "cache.h"
#include "tree-walk.h"
#include "xdiff-interface.h"
#include "blob.h"

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 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";
}

extern void *merge_file(struct blob *, struct blob *, struct blob *, unsigned long *);

static void *result(struct merge_list *entry, unsigned long *size)
{
	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 *origin(struct merge_list *entry, unsigned long *size)
{
	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 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 = 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;
	}
}

/* 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 = xcalloc(1, sizeof(*res));

	res->stage = stage;
	res->path = path;
	res->mode = mode;
	res->blob = lookup_blob(sha1);
	return res;
}

static char *traverse_path(const struct traverse_info *info, const struct name_entry *n)
{
	char *path = xmalloc(traverse_path_len(info, n) + 1);
	return make_traverse_path(path, info, n);
}

static void resolve(const struct traverse_info *info, 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 = traverse_path(info, result);
	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 struct traverse_info *info, struct name_entry n[3])
{
	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;
	newbase = traverse_path(info, p);
	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 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->sha1, path);
	link->link = entry;
	return link;
}

static void unresolved(const struct traverse_info *info, struct name_entry n[3])
{
	struct merge_list *entry = NULL;

	if (unresolved_directory(info, n))
		return;

	/*
	 * 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, info, n + 2, entry);
	entry = link_entry(2, info, n + 1, entry);
	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)) {
		if (entry[0].sha1) {
			resolve(info, NULL, entry+1);
			return mask;
		}
	}

	if (same_entry(entry+0, entry+1)) {
		if (entry[2].sha1 && !S_ISDIR(entry[2].mode)) {
			resolve(info, entry+1, entry+2);
			return mask;
		}
	}

	if (same_entry(entry+0, entry+2)) {
		if (entry[1].sha1 && !S_ISDIR(entry[1].mode)) {
			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)
{
	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)
{
	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);

	show_result();
	return 0;
}
Commit	Line	Data
492e0759	1	#include "cache.h"
1b0c7174	2	#include "tree-walk.h"
0c799383	3	#include "xdiff-interface.h"
83788070	4	#include "blob.h"
492e0759 LT	5
	6	static const char merge_tree_usage[] = "git-merge-tree <base-tree> <branch1> <branch2>";
	7	static int resolve_directories = 1;
	8
83788070 LT	9	struct merge_list {
	10	struct merge_list *next;
	11	struct merge_list link; / other stages for this object */
	12
	13	unsigned int stage : 2,
	14	flags : 30;
	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
492e0759 LT	28	static void merge_trees(struct tree_desc t[3], const char *base);
492e0759 LT	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	extern void merge_file(struct blob , struct blob , struct blob , unsigned long *);
	57
	58	static void result(struct merge_list entry, unsigned long *size)
	59	{
21666f1a	60	enum object_type type;
0c799383 LT	61	struct blob base, our, *their;
	62
	63	if (!entry->stage)
21666f1a	64	return read_sha1_file(entry->blob->object.sha1, &type, size);
0c799383 LT	65	base = NULL;
	66	if (entry->stage == 1) {
	67	base = entry->blob;
	68	entry = entry->link;
	69	}
	70	our = NULL;
	71	if (entry && entry->stage == 2) {
	72	our = entry->blob;
	73	entry = entry->link;
	74	}
	75	their = NULL;
	76	if (entry)
	77	their = entry->blob;
	78	return merge_file(base, our, their, size);
	79	}
	80
	81	static void origin(struct merge_list entry, unsigned long *size)
	82	{
21666f1a	83	enum object_type type;
0c799383 LT	84	while (entry) {
0c799383 LT	85	if (entry->stage == 2)
21666f1a	86	return read_sha1_file(entry->blob->object.sha1, &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
	108	xpp.flags = XDF_NEED_MINIMAL;
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;
c279d7e9	122	xdi_diff(&src, &dst, &xpp, &xecfg, &ecb);
0c799383 LT	123	free(src.ptr);
	124	free(dst.ptr);
	125	}
	126
83788070 LT	127	static void show_result_list(struct merge_list *entry)
	128	{
	129	printf("%s\n", explanation(entry));
	130	do {
	131	struct merge_list *link = entry->link;
	132	static const char *desc[4] = { "result", "base", "our", "their" };
	133	printf(" %-6s %o %s %s\n", desc[entry->stage], entry->mode, sha1_to_hex(entry->blob->object.sha1), entry->path);
	134	entry = link;
	135	} while (entry);
	136	}
	137
	138	static void show_result(void)
	139	{
	140	struct merge_list *walk;
	141
	142	walk = merge_result;
	143	while (walk) {
	144	show_result_list(walk);
0c799383	145	show_diff(walk);
83788070 LT	146	walk = walk->next;
	147	}
	148	}
	149
492e0759 LT	150	/* An empty entry never compares same, not even to another empty entry */
	151	static int same_entry(struct name_entry a, struct name_entry b)
	152	{
	153	return a->sha1 &&
	154	b->sha1 &&
a89fccd2	155	!hashcmp(a->sha1, b->sha1) &&
492e0759 LT	156	a->mode == b->mode;
	157	}
	158
83788070	159	static struct merge_list create_entry(unsigned stage, unsigned mode, const unsigned char sha1, const char *path)
492e0759	160	{
19d4b416	161	struct merge_list res = xcalloc(1, sizeof(res));
83788070	162
83788070 LT	163	res->stage = stage;
	164	res->path = path;
	165	res->mode = mode;
	166	res->blob = lookup_blob(sha1);
	167	return res;
01df5297 LT	168	}
01df5297 LT	169
40d934df LT	170	static char traverse_path(const struct traverse_info info, const struct name_entry *n)
	171	{
	172	char *path = xmalloc(traverse_path_len(info, n) + 1);
	173	return make_traverse_path(path, info, n);
	174	}
	175
	176	static void resolve(const struct traverse_info info, struct name_entry branch1, struct name_entry *result)
01df5297	177	{
83788070 LT	178	struct merge_list orig, final;
	179	const char *path;
	180
01df5297 LT	181	/* If it's already branch1, don't bother showing it */
	182	if (!branch1)
	183	return;
01df5297	184
40d934df	185	path = traverse_path(info, result);
83788070 LT	186	orig = create_entry(2, branch1->mode, branch1->sha1, path);
	187	final = create_entry(0, result->mode, result->sha1, path);
	188
	189	final->link = orig;
	190
	191	add_merge_entry(final);
492e0759 LT	192	}
492e0759 LT	193
40d934df	194	static int unresolved_directory(const struct traverse_info *info, struct name_entry n[3])
492e0759	195	{
492e0759 LT	196	char *newbase;
	197	struct name_entry *p;
	198	struct tree_desc t[3];
	199	void buf0, buf1, *buf2;
	200
	201	if (!resolve_directories)
	202	return 0;
	203	p = n;
	204	if (!p->mode) {
	205	p++;
	206	if (!p->mode)
	207	p++;
	208	}
	209	if (!S_ISDIR(p->mode))
	210	return 0;
40d934df	211	newbase = traverse_path(info, p);
492e0759 LT	212	buf0 = fill_tree_descriptor(t+0, n[0].sha1);
	213	buf1 = fill_tree_descriptor(t+1, n[1].sha1);
	214	buf2 = fill_tree_descriptor(t+2, n[2].sha1);
	215	merge_trees(t, newbase);
	216
	217	free(buf0);
	218	free(buf1);
	219	free(buf2);
	220	free(newbase);
	221	return 1;
	222	}
	223
83788070	224
40d934df	225	static struct merge_list link_entry(unsigned stage, const struct traverse_info info, struct name_entry n, struct merge_list entry)
83788070 LT	226	{
	227	const char *path;
	228	struct merge_list *link;
	229
	230	if (!n->mode)
	231	return entry;
	232	if (entry)
	233	path = entry->path;
	234	else
40d934df	235	path = traverse_path(info, n);
83788070 LT	236	link = create_entry(stage, n->mode, n->sha1, path);
	237	link->link = entry;
	238	return link;
	239	}
	240
40d934df	241	static void unresolved(const struct traverse_info *info, struct name_entry n[3])
492e0759	242	{
83788070 LT	243	struct merge_list *entry = NULL;
83788070 LT	244
40d934df	245	if (unresolved_directory(info, n))
492e0759	246	return;
83788070 LT	247
	248	/*
	249	* Do them in reverse order so that the resulting link
	250	* list has the stages in order - link_entry adds new
	251	* links at the front.
	252	*/
40d934df LT	253	entry = link_entry(3, info, n + 2, entry);
	254	entry = link_entry(2, info, n + 1, entry);
	255	entry = link_entry(1, info, n + 0, entry);
83788070 LT	256
83788070 LT	257	add_merge_entry(entry);
492e0759 LT	258	}
492e0759 LT	259
164dcb97 LT	260	/*
	261	* Merge two trees together (t[1] and t[2]), using a common base (t[0])
	262	* as the origin.
	263	*
	264	* This walks the (sorted) trees in lock-step, checking every possible
	265	* name. Note that directories automatically sort differently from other
	266	* files (see "base_name_compare"), so you'll never see file/directory
	267	* conflicts, because they won't ever compare the same.
	268	*
	269	* IOW, if a directory changes to a filename, it will automatically be
	270	* seen as the directory going away, and the filename being created.
	271	*
	272	* Think of this as a three-way diff.
	273	*
	274	* The output will be either:
	275	* - successful merge
	276	* "0 mode sha1 filename"
	277	* NOTE NOTE NOTE! FIXME! We really really need to walk the index
	278	* in parallel with this too!
	279	*
	280	* - conflict:
	281	* "1 mode sha1 filename"
	282	* "2 mode sha1 filename"
	283	* "3 mode sha1 filename"
	284	* where not all of the 1/2/3 lines may exist, of course.
	285	*
	286	* The successful merge rules are the same as for the three-way merge
	287	* in git-read-tree.
	288	*/
91e4f036	289	static int threeway_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry entry, struct traverse_info info)
164dcb97 LT	290	{
	291	/* Same in both? */
	292	if (same_entry(entry+1, entry+2)) {
	293	if (entry[0].sha1) {
40d934df	294	resolve(info, NULL, entry+1);
5803c6f8	295	return mask;
492e0759	296	}
164dcb97	297	}
492e0759	298
164dcb97 LT	299	if (same_entry(entry+0, entry+1)) {
164dcb97 LT	300	if (entry[2].sha1 && !S_ISDIR(entry[2].mode)) {
40d934df	301	resolve(info, entry+1, entry+2);
5803c6f8	302	return mask;
492e0759	303	}
164dcb97	304	}
492e0759	305
164dcb97 LT	306	if (same_entry(entry+0, entry+2)) {
164dcb97 LT	307	if (entry[1].sha1 && !S_ISDIR(entry[1].mode)) {
40d934df	308	resolve(info, NULL, entry+1);
5803c6f8	309	return mask;
492e0759	310	}
492e0759	311	}
164dcb97	312
40d934df	313	unresolved(info, entry);
5803c6f8	314	return mask;
164dcb97 LT	315	}
	316
	317	static void merge_trees(struct tree_desc t[3], const char *base)
	318	{
40d934df LT	319	struct traverse_info info;
	320
	321	setup_traverse_info(&info, base);
	322	info.fn = threeway_callback;
	323	traverse_trees(3, t, &info);
492e0759 LT	324	}
	325
	326	static void get_tree_descriptor(struct tree_desc desc, const char *rev)
	327	{
	328	unsigned char sha1[20];
	329	void *buf;
	330
31fff305	331	if (get_sha1(rev, sha1))
492e0759 LT	332	die("unknown rev %s", rev);
	333	buf = fill_tree_descriptor(desc, sha1);
	334	if (!buf)
	335	die("%s is not a tree", rev);
	336	return buf;
	337	}
	338
	339	int main(int argc, char **argv)
	340	{
	341	struct tree_desc t[3];
	342	void buf1, buf2, *buf3;
	343
5b6df8e4	344	if (argc != 4)
492e0759 LT	345	usage(merge_tree_usage);
492e0759 LT	346
8112894d DL	347	setup_git_directory();
8112894d DL	348
492e0759 LT	349	buf1 = get_tree_descriptor(t+0, argv[1]);
	350	buf2 = get_tree_descriptor(t+1, argv[2]);
	351	buf3 = get_tree_descriptor(t+2, argv[3]);
	352	merge_trees(t, "");
	353	free(buf1);
	354	free(buf2);
	355	free(buf3);
83788070 LT	356
83788070 LT	357	show_result();
492e0759 LT	358	return 0;
492e0759 LT	359	}