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

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

	git_extract_argv0_path(argv[0]);

	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"
2fb3f6db	5	#include "exec_cmd.h"
492e0759	6
34263de0	7	static const char merge_tree_usage[] = "git merge-tree <base-tree> <branch1> <branch2>";
492e0759 LT	8	static int resolve_directories = 1;
492e0759 LT	9
83788070 LT	10	struct merge_list {
	11	struct merge_list *next;
	12	struct merge_list link; / other stages for this object */
	13
	14	unsigned int stage : 2,
	15	flags : 30;
	16	unsigned int mode;
	17	const char *path;
	18	struct blob *blob;
	19	};
	20
	21	static struct merge_list merge_result, *merge_result_end = &merge_result;
	22
	23	static void add_merge_entry(struct merge_list *entry)
	24	{
	25	*merge_result_end = entry;
	26	merge_result_end = &entry->next;
	27	}
	28
492e0759 LT	29	static void merge_trees(struct tree_desc t[3], const char *base);
492e0759 LT	30
83788070 LT	31	static const char explanation(struct merge_list entry)
	32	{
	33	switch (entry->stage) {
	34	case 0:
	35	return "merged";
	36	case 3:
	37	return "added in remote";
	38	case 2:
	39	if (entry->link)
	40	return "added in both";
	41	return "added in local";
	42	}
	43
	44	/* Existed in base */
	45	entry = entry->link;
	46	if (!entry)
	47	return "removed in both";
	48
	49	if (entry->link)
	50	return "changed in both";
	51
	52	if (entry->stage == 3)
	53	return "removed in local";
	54	return "removed in remote";
	55	}
	56
0c799383 LT	57	extern void merge_file(struct blob , struct blob , struct blob , unsigned long *);
	58
	59	static void result(struct merge_list entry, unsigned long *size)
	60	{
21666f1a	61	enum object_type type;
0c799383 LT	62	struct blob base, our, *their;
	63
	64	if (!entry->stage)
21666f1a	65	return read_sha1_file(entry->blob->object.sha1, &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;
	79	return merge_file(base, our, their, size);
	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)
21666f1a	87	return read_sha1_file(entry->blob->object.sha1, &type, size);
0c799383 LT	88	entry = entry->link;
	89	}
	90	return NULL;
	91	}
	92
	93	static int show_outf(void priv_, mmbuffer_t mb, int nbuf)
	94	{
	95	int i;
	96	for (i = 0; i < nbuf; i++)
	97	printf("%.*s", (int) mb[i].size, mb[i].ptr);
	98	return 0;
	99	}
	100
	101	static void show_diff(struct merge_list *entry)
	102	{
	103	unsigned long size;
	104	mmfile_t src, dst;
	105	xpparam_t xpp;
	106	xdemitconf_t xecfg;
	107	xdemitcb_t ecb;
	108
	109	xpp.flags = XDF_NEED_MINIMAL;
30b25010	110	memset(&xecfg, 0, sizeof(xecfg));
0c799383	111	xecfg.ctxlen = 3;
0c799383 LT	112	ecb.outf = show_outf;
	113	ecb.priv = NULL;
	114
	115	src.ptr = origin(entry, &size);
	116	if (!src.ptr)
	117	size = 0;
	118	src.size = size;
	119	dst.ptr = result(entry, &size);
	120	if (!dst.ptr)
	121	size = 0;
	122	dst.size = size;
c279d7e9	123	xdi_diff(&src, &dst, &xpp, &xecfg, &ecb);
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" };
	134	printf(" %-6s %o %s %s\n", desc[entry->stage], entry->mode, sha1_to_hex(entry->blob->object.sha1), entry->path);
	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	{
	154	return a->sha1 &&
	155	b->sha1 &&
a89fccd2	156	!hashcmp(a->sha1, b->sha1) &&
492e0759 LT	157	a->mode == b->mode;
	158	}
	159
83788070	160	static struct merge_list create_entry(unsigned stage, unsigned mode, const unsigned char sha1, const char *path)
492e0759	161	{
19d4b416	162	struct merge_list res = xcalloc(1, sizeof(res));
83788070	163
83788070 LT	164	res->stage = stage;
	165	res->path = path;
	166	res->mode = mode;
	167	res->blob = lookup_blob(sha1);
	168	return res;
01df5297 LT	169	}
01df5297 LT	170
40d934df LT	171	static char traverse_path(const struct traverse_info info, const struct name_entry *n)
	172	{
	173	char *path = xmalloc(traverse_path_len(info, n) + 1);
	174	return make_traverse_path(path, info, n);
	175	}
	176
	177	static void resolve(const struct traverse_info info, struct name_entry branch1, struct name_entry *result)
01df5297	178	{
83788070 LT	179	struct merge_list orig, final;
	180	const char *path;
	181
01df5297 LT	182	/* If it's already branch1, don't bother showing it */
	183	if (!branch1)
	184	return;
01df5297	185
40d934df	186	path = traverse_path(info, result);
83788070 LT	187	orig = create_entry(2, branch1->mode, branch1->sha1, path);
	188	final = create_entry(0, result->mode, result->sha1, path);
	189
	190	final->link = orig;
	191
	192	add_merge_entry(final);
492e0759 LT	193	}
492e0759 LT	194
40d934df	195	static int unresolved_directory(const struct traverse_info *info, struct name_entry n[3])
492e0759	196	{
492e0759 LT	197	char *newbase;
	198	struct name_entry *p;
	199	struct tree_desc t[3];
	200	void buf0, buf1, *buf2;
	201
	202	if (!resolve_directories)
	203	return 0;
	204	p = n;
	205	if (!p->mode) {
	206	p++;
	207	if (!p->mode)
	208	p++;
	209	}
	210	if (!S_ISDIR(p->mode))
	211	return 0;
40d934df	212	newbase = traverse_path(info, p);
492e0759 LT	213	buf0 = fill_tree_descriptor(t+0, n[0].sha1);
	214	buf1 = fill_tree_descriptor(t+1, n[1].sha1);
	215	buf2 = fill_tree_descriptor(t+2, n[2].sha1);
	216	merge_trees(t, newbase);
	217
	218	free(buf0);
	219	free(buf1);
	220	free(buf2);
	221	free(newbase);
	222	return 1;
	223	}
	224
83788070	225
40d934df	226	static struct merge_list link_entry(unsigned stage, const struct traverse_info info, struct name_entry n, struct merge_list entry)
83788070 LT	227	{
	228	const char *path;
	229	struct merge_list *link;
	230
	231	if (!n->mode)
	232	return entry;
	233	if (entry)
	234	path = entry->path;
	235	else
40d934df	236	path = traverse_path(info, n);
83788070 LT	237	link = create_entry(stage, n->mode, n->sha1, path);
	238	link->link = entry;
	239	return link;
	240	}
	241
40d934df	242	static void unresolved(const struct traverse_info *info, struct name_entry n[3])
492e0759	243	{
83788070 LT	244	struct merge_list *entry = NULL;
83788070 LT	245
40d934df	246	if (unresolved_directory(info, n))
492e0759	247	return;
83788070 LT	248
	249	/*
	250	* Do them in reverse order so that the resulting link
	251	* list has the stages in order - link_entry adds new
	252	* links at the front.
	253	*/
40d934df LT	254	entry = link_entry(3, info, n + 2, entry);
	255	entry = link_entry(2, info, n + 1, entry);
	256	entry = link_entry(1, info, n + 0, entry);
83788070 LT	257
83788070 LT	258	add_merge_entry(entry);
492e0759 LT	259	}
492e0759 LT	260
164dcb97 LT	261	/*
	262	* Merge two trees together (t[1] and t[2]), using a common base (t[0])
	263	* as the origin.
	264	*
	265	* This walks the (sorted) trees in lock-step, checking every possible
	266	* name. Note that directories automatically sort differently from other
	267	* files (see "base_name_compare"), so you'll never see file/directory
	268	* conflicts, because they won't ever compare the same.
	269	*
	270	* IOW, if a directory changes to a filename, it will automatically be
	271	* seen as the directory going away, and the filename being created.
	272	*
	273	* Think of this as a three-way diff.
	274	*
	275	* The output will be either:
	276	* - successful merge
	277	* "0 mode sha1 filename"
	278	* NOTE NOTE NOTE! FIXME! We really really need to walk the index
	279	* in parallel with this too!
	280	*
	281	* - conflict:
	282	* "1 mode sha1 filename"
	283	* "2 mode sha1 filename"
	284	* "3 mode sha1 filename"
	285	* where not all of the 1/2/3 lines may exist, of course.
	286	*
	287	* The successful merge rules are the same as for the three-way merge
	288	* in git-read-tree.
	289	*/
91e4f036	290	static int threeway_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry entry, struct traverse_info info)
164dcb97 LT	291	{
	292	/* Same in both? */
	293	if (same_entry(entry+1, entry+2)) {
	294	if (entry[0].sha1) {
40d934df	295	resolve(info, NULL, entry+1);
5803c6f8	296	return mask;
492e0759	297	}
164dcb97	298	}
492e0759	299
164dcb97 LT	300	if (same_entry(entry+0, entry+1)) {
164dcb97 LT	301	if (entry[2].sha1 && !S_ISDIR(entry[2].mode)) {
40d934df	302	resolve(info, entry+1, entry+2);
5803c6f8	303	return mask;
492e0759	304	}
164dcb97	305	}
492e0759	306
164dcb97 LT	307	if (same_entry(entry+0, entry+2)) {
164dcb97 LT	308	if (entry[1].sha1 && !S_ISDIR(entry[1].mode)) {
40d934df	309	resolve(info, NULL, entry+1);
5803c6f8	310	return mask;
492e0759	311	}
492e0759	312	}
164dcb97	313
40d934df	314	unresolved(info, entry);
5803c6f8	315	return mask;
164dcb97 LT	316	}
	317
	318	static void merge_trees(struct tree_desc t[3], const char *base)
	319	{
40d934df LT	320	struct traverse_info info;
	321
	322	setup_traverse_info(&info, base);
	323	info.fn = threeway_callback;
	324	traverse_trees(3, t, &info);
492e0759 LT	325	}
	326
	327	static void get_tree_descriptor(struct tree_desc desc, const char *rev)
	328	{
	329	unsigned char sha1[20];
	330	void *buf;
	331
31fff305	332	if (get_sha1(rev, sha1))
492e0759 LT	333	die("unknown rev %s", rev);
	334	buf = fill_tree_descriptor(desc, sha1);
	335	if (!buf)
	336	die("%s is not a tree", rev);
	337	return buf;
	338	}
	339
	340	int main(int argc, char **argv)
	341	{
	342	struct tree_desc t[3];
	343	void buf1, buf2, *buf3;
	344
5b6df8e4	345	if (argc != 4)
492e0759 LT	346	usage(merge_tree_usage);
492e0759 LT	347
2fb3f6db SP	348	git_extract_argv0_path(argv[0]);
2fb3f6db SP	349
8112894d DL	350	setup_git_directory();
8112894d DL	351
492e0759 LT	352	buf1 = get_tree_descriptor(t+0, argv[1]);
	353	buf2 = get_tree_descriptor(t+1, argv[2]);
	354	buf3 = get_tree_descriptor(t+2, argv[3]);
	355	merge_trees(t, "");
	356	free(buf1);
	357	free(buf2);
	358	free(buf3);
83788070 LT	359
83788070 LT	360	show_result();
492e0759 LT	361	return 0;
492e0759 LT	362	}