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

/*
 * GIT - The information manager from hell
 *
 * Copyright (C) Linus Torvalds, 2005
 */
#include "cache.h"

static int stage = 0;

static int read_one_entry(unsigned char *sha1, const char *base, int baselen, const char *pathname, unsigned mode)
{
	int len = strlen(pathname);
	unsigned int size = cache_entry_size(baselen + len);
	struct cache_entry *ce = malloc(size);

	memset(ce, 0, size);

	ce->ce_mode = create_ce_mode(mode);
	ce->ce_flags = create_ce_flags(baselen + len, stage);
	memcpy(ce->name, base, baselen);
	memcpy(ce->name + baselen, pathname, len+1);
	memcpy(ce->sha1, sha1, 20);
	return add_cache_entry(ce, 1);
}

static int read_tree_recursive(void *buffer, const char *type,
			       unsigned long size,
			       const char *base, int baselen)
{
	if (!buffer || strcmp(type, "tree"))
		return -1;
	while (size) {
		int len = strlen(buffer)+1;
		unsigned char *sha1 = buffer + len;
		char *path = strchr(buffer, ' ')+1;
		unsigned int mode;

		if (size < len + 20 || sscanf(buffer, "%o", &mode) != 1)
			return -1;

		buffer = sha1 + 20;
		size -= len + 20;

		if (S_ISDIR(mode)) {
			int retval;
			int pathlen = strlen(path);
			char *newbase = malloc(baselen + 1 + pathlen);
			void *eltbuf;
			char elttype[20];
			unsigned long eltsize;

			eltbuf = read_sha1_file(sha1, elttype, &eltsize);
			if (!eltbuf)
				return -1;
			memcpy(newbase, base, baselen);
			memcpy(newbase + baselen, path, pathlen);
			newbase[baselen + pathlen] = '/';
			retval = read_tree_recursive(eltbuf, elttype, eltsize,
						     newbase,
						     baselen + pathlen + 1);
			free(eltbuf);
			free(newbase);
			if (retval)
				return -1;
			continue;
		}
		if (read_one_entry(sha1, base, baselen, path, mode) < 0)
			return -1;
	}
	return 0;
}

static int read_tree(unsigned char *sha1, const char *base, int baselen)
{
	void *buffer;
	unsigned long size;

	buffer = read_tree_with_tree_or_commit_sha1(sha1, &size, 0);
	return read_tree_recursive(buffer, "tree", size, base, baselen);
}

static char *lockfile_name;

static void remove_lock_file(void)
{
	if (lockfile_name)
		unlink(lockfile_name);
}

static int path_matches(struct cache_entry *a, struct cache_entry *b)
{
	int len = ce_namelen(a);
	return ce_namelen(b) == len &&
		!memcmp(a->name, b->name, len);
}

static int same(struct cache_entry *a, struct cache_entry *b)
{
	return a->ce_mode == b->ce_mode && 
		!memcmp(a->sha1, b->sha1, 20);
}


/*
 * This removes all trivial merges that don't change the tree
 * and collapses them to state 0.
 *
 * _Any_ other merge is left to user policy.  That includes "both
 * created the same file", and "both removed the same file" - which are
 * trivial, but the user might still want to _note_ it. 
 */
static struct cache_entry *merge_entries(struct cache_entry *a,
					 struct cache_entry *b,
					 struct cache_entry *c)
{
	int len = ce_namelen(a);

	/*
	 * Are they all the same filename? We won't do
	 * any name merging
	 */
	if (ce_namelen(b) != len ||
	    ce_namelen(c) != len ||
	    memcmp(a->name, b->name, len) ||
	    memcmp(a->name, c->name, len))
		return NULL;

	/*
	 * Ok, all three entries describe the same
	 * filename, but maybe the contents or file
	 * mode have changed?
	 *
	 * The trivial cases end up being the ones where two
	 * out of three files are the same:
	 *  - both destinations the same, trivially take either
	 *  - one of the destination versions hasn't changed,
	 *    take the other.
	 *
	 * The "all entries exactly the same" case falls out as
	 * a special case of any of the "two same" cases.
	 *
	 * Here "a" is "original", and "b" and "c" are the two
	 * trees we are merging.
	 */
	if (same(b,c))
		return c;
	if (same(a,b))
		return c;
	if (same(a,c))
		return b;
	return NULL;
}

static void trivially_merge_cache(struct cache_entry **src, int nr)
{
	static struct cache_entry null_entry;
	struct cache_entry **dst = src;
	struct cache_entry *old = &null_entry;

	while (nr) {
		struct cache_entry *ce, *result;

		ce = src[0];

		/* We throw away original cache entries except for the stat information */
		if (!ce_stage(ce)) {
			old = ce;
			src++;
			nr--;
			active_nr--;
			continue;
		}
		if (nr > 2 && (result = merge_entries(ce, src[1], src[2])) != NULL) {
			/*
			 * See if we can re-use the old CE directly?
			 * That way we get the uptodate stat info.
			 */
			if (path_matches(result, old) && same(result, old))
				*result = *old;
			ce = result;
			ce->ce_flags &= ~htons(CE_STAGEMASK);
			src += 2;
			nr -= 2;
			active_nr -= 2;
		}
		*dst++ = ce;
		src++;
		nr--;
	}
}

static void merge_stat_info(struct cache_entry **src, int nr)
{
	static struct cache_entry null_entry;
	struct cache_entry **dst = src;
	struct cache_entry *old = &null_entry;

	while (nr) {
		struct cache_entry *ce;

		ce = src[0];

		/* We throw away original cache entries except for the stat information */
		if (!ce_stage(ce)) {
			old = ce;
			src++;
			nr--;
			active_nr--;
			continue;
		}
		if (path_matches(ce, old) && same(ce, old))
			*ce = *old;
		ce->ce_flags &= ~htons(CE_STAGEMASK);
		*dst++ = ce;
		src++;
		nr--;
	}
}

static char *read_tree_usage = "read-tree (<sha> | -m <sha1> [<sha2> <sha3>])";

int main(int argc, char **argv)
{
	int i, newfd, merge;
	unsigned char sha1[20];
	static char lockfile[MAXPATHLEN+1];
	const char *indexfile = get_index_file();

	snprintf(lockfile, sizeof(lockfile), "%s.lock", indexfile);

	newfd = open(lockfile, O_RDWR | O_CREAT | O_EXCL, 0600);
	if (newfd < 0)
		die("unable to create new cachefile");
	atexit(remove_lock_file);
	lockfile_name = lockfile;

	merge = 0;
	for (i = 1; i < argc; i++) {
		const char *arg = argv[i];

		/* "-m" stands for "merge", meaning we start in stage 1 */
		if (!strcmp(arg, "-m")) {
			int i;
			if (stage)
				die("-m needs to come first");
			read_cache();
			for (i = 0; i < active_nr; i++) {
				if (ce_stage(active_cache[i]))
					die("you need to resolve your current index first");
			}
			stage = 1;
			merge = 1;
			continue;
		}
		if (get_sha1_hex(arg, sha1) < 0)
			usage(read_tree_usage);
		if (stage > 3)
			usage(read_tree_usage);
		if (read_tree(sha1, "", 0) < 0)
			die("failed to unpack tree object %s", arg);
		stage++;
	}
	if (merge) {
		switch (stage) {
		case 4:	/* Three-way merge */
			trivially_merge_cache(active_cache, active_nr);
			break;
		case 2:	/* Just read a tree, merge with old cache contents */
			merge_stat_info(active_cache, active_nr);
			break;
		default:
			die("just how do you expect me to merge %d trees?", stage-1);
		}
	}
	if (write_cache(newfd, active_cache, active_nr) || rename(lockfile, indexfile))
		die("unable to write new index file");
	lockfile_name = NULL;
	return 0;
}
Commit	Line	Data
8bc9a0c7 LT	1	/*
	2	* GIT - The information manager from hell
	3	*
	4	* Copyright (C) Linus Torvalds, 2005
	5	*/
e83c5163 LT	6	#include "cache.h"
e83c5163 LT	7
d99082e0 LT	8	static int stage = 0;
d99082e0 LT	9
f768846e	10	static int read_one_entry(unsigned char sha1, const char base, int baselen, const char *pathname, unsigned mode)
e497ea2a	11	{
83adac3c	12	int len = strlen(pathname);
f768846e	13	unsigned int size = cache_entry_size(baselen + len);
83adac3c	14	struct cache_entry *ce = malloc(size);
e497ea2a	15
83adac3c	16	memset(ce, 0, size);
e497ea2a	17
e4479470	18	ce->ce_mode = create_ce_mode(mode);
d99082e0	19	ce->ce_flags = create_ce_flags(baselen + len, stage);
f768846e LT	20	memcpy(ce->name, base, baselen);
f768846e LT	21	memcpy(ce->name + baselen, pathname, len+1);
83adac3c	22	memcpy(ce->sha1, sha1, 20);
121481ab	23	return add_cache_entry(ce, 1);
e497ea2a LT	24	}
e497ea2a LT	25
b12ec373 JH	26	static int read_tree_recursive(void buffer, const char type,
	27	unsigned long size,
	28	const char *base, int baselen)
e83c5163	29	{
b12ec373	30	if (!buffer \|\| strcmp(type, "tree"))
83adac3c	31	return -1;
e83c5163 LT	32	while (size) {
	33	int len = strlen(buffer)+1;
	34	unsigned char *sha1 = buffer + len;
	35	char *path = strchr(buffer, ' ')+1;
	36	unsigned int mode;
e497ea2a	37
e83c5163	38	if (size < len + 20 \|\| sscanf(buffer, "%o", &mode) != 1)
83adac3c LT	39	return -1;
83adac3c LT	40
e83c5163 LT	41	buffer = sha1 + 20;
e83c5163 LT	42	size -= len + 20;
83adac3c	43
f768846e LT	44	if (S_ISDIR(mode)) {
	45	int retval;
	46	int pathlen = strlen(path);
	47	char *newbase = malloc(baselen + 1 + pathlen);
b12ec373 JH	48	void *eltbuf;
	49	char elttype[20];
	50	unsigned long eltsize;
	51
	52	eltbuf = read_sha1_file(sha1, elttype, &eltsize);
	53	if (!eltbuf)
	54	return -1;
f768846e LT	55	memcpy(newbase, base, baselen);
	56	memcpy(newbase + baselen, path, pathlen);
	57	newbase[baselen + pathlen] = '/';
b12ec373 JH	58	retval = read_tree_recursive(eltbuf, elttype, eltsize,
	59	newbase,
	60	baselen + pathlen + 1);
	61	free(eltbuf);
f768846e LT	62	free(newbase);
	63	if (retval)
	64	return -1;
	65	continue;
	66	}
	67	if (read_one_entry(sha1, base, baselen, path, mode) < 0)
83adac3c	68	return -1;
e83c5163 LT	69	}
	70	return 0;
	71	}
	72
b12ec373 JH	73	static int read_tree(unsigned char sha1, const char base, int baselen)
	74	{
	75	void *buffer;
	76	unsigned long size;
	77
	78	buffer = read_tree_with_tree_or_commit_sha1(sha1, &size, 0);
	79	return read_tree_recursive(buffer, "tree", size, base, baselen);
	80	}
	81
bb233d69	82	static char *lockfile_name;
9614b8dc LT	83
	84	static void remove_lock_file(void)
	85	{
bb233d69 LT	86	if (lockfile_name)
bb233d69 LT	87	unlink(lockfile_name);
9614b8dc LT	88	}
9614b8dc LT	89
ca016f0e LT	90	static int path_matches(struct cache_entry a, struct cache_entry b)
	91	{
	92	int len = ce_namelen(a);
	93	return ce_namelen(b) == len &&
	94	!memcmp(a->name, b->name, len);
	95	}
	96
43f91266 LT	97	static int same(struct cache_entry a, struct cache_entry b)
	98	{
	99	return a->ce_mode == b->ce_mode &&
	100	!memcmp(a->sha1, b->sha1, 20);
	101	}
	102
	103
d99082e0	104	/*
43f91266 LT	105	* This removes all trivial merges that don't change the tree
43f91266 LT	106	* and collapses them to state 0.
d99082e0	107	*
43f91266 LT	108	* _Any_ other merge is left to user policy. That includes "both
	109	* created the same file", and "both removed the same file" - which are
	110	* trivial, but the user might still want to _note_ it.
d99082e0	111	*/
43f91266 LT	112	static struct cache_entry merge_entries(struct cache_entry a,
	113	struct cache_entry *b,
	114	struct cache_entry *c)
d99082e0 LT	115	{
d99082e0 LT	116	int len = ce_namelen(a);
43f91266 LT	117
	118	/*
	119	* Are they all the same filename? We won't do
	120	* any name merging
	121	*/
	122	if (ce_namelen(b) != len \|\|
	123	ce_namelen(c) != len \|\|
	124	memcmp(a->name, b->name, len) \|\|
	125	memcmp(a->name, c->name, len))
	126	return NULL;
	127
	128	/*
	129	* Ok, all three entries describe the same
	130	* filename, but maybe the contents or file
	131	* mode have changed?
	132	*
	133	* The trivial cases end up being the ones where two
	134	* out of three files are the same:
	135	* - both destinations the same, trivially take either
	136	* - one of the destination versions hasn't changed,
	137	* take the other.
	138	*
	139	* The "all entries exactly the same" case falls out as
	140	* a special case of any of the "two same" cases.
	141	*
	142	* Here "a" is "original", and "b" and "c" are the two
	143	* trees we are merging.
	144	*/
	145	if (same(b,c))
	146	return c;
	147	if (same(a,b))
	148	return c;
	149	if (same(a,c))
	150	return b;
	151	return NULL;
d99082e0 LT	152	}
	153
	154	static void trivially_merge_cache(struct cache_entry **src, int nr)
	155	{
ca016f0e	156	static struct cache_entry null_entry;
d99082e0	157	struct cache_entry **dst = src;
ca016f0e	158	struct cache_entry *old = &null_entry;
d99082e0 LT	159
d99082e0 LT	160	while (nr) {
43f91266	161	struct cache_entry ce, result;
d99082e0 LT	162
d99082e0 LT	163	ce = src[0];
ca016f0e LT	164
	165	/* We throw away original cache entries except for the stat information */
	166	if (!ce_stage(ce)) {
	167	old = ce;
	168	src++;
	169	nr--;
	170	active_nr--;
	171	continue;
	172	}
43f91266	173	if (nr > 2 && (result = merge_entries(ce, src[1], src[2])) != NULL) {
ca016f0e LT	174	/*
	175	* See if we can re-use the old CE directly?
	176	* That way we get the uptodate stat info.
	177	*/
	178	if (path_matches(result, old) && same(result, old))
	179	result = old;
43f91266	180	ce = result;
d99082e0 LT	181	ce->ce_flags &= ~htons(CE_STAGEMASK);
	182	src += 2;
	183	nr -= 2;
	184	active_nr -= 2;
	185	}
a3a65234 LT	186	*dst++ = ce;
	187	src++;
	188	nr--;
	189	}
	190	}
	191
	192	static void merge_stat_info(struct cache_entry **src, int nr)
	193	{
	194	static struct cache_entry null_entry;
	195	struct cache_entry **dst = src;
	196	struct cache_entry *old = &null_entry;
	197
	198	while (nr) {
	199	struct cache_entry *ce;
	200
	201	ce = src[0];
	202
	203	/* We throw away original cache entries except for the stat information */
	204	if (!ce_stage(ce)) {
	205	old = ce;
	206	src++;
	207	nr--;
	208	active_nr--;
	209	continue;
	210	}
	211	if (path_matches(ce, old) && same(ce, old))
	212	ce = old;
	213	ce->ce_flags &= ~htons(CE_STAGEMASK);
	214	*dst++ = ce;
d99082e0	215	src++;
d99082e0 LT	216	nr--;
	217	}
	218	}
	219
c5bac17a JH	220	static char *read_tree_usage = "read-tree (<sha> \| -m <sha1> [<sha2> <sha3>])";
c5bac17a JH	221
e83c5163 LT	222	int main(int argc, char **argv)
e83c5163 LT	223	{
ca016f0e	224	int i, newfd, merge;
e83c5163	225	unsigned char sha1[20];
bb233d69 LT	226	static char lockfile[MAXPATHLEN+1];
bb233d69 LT	227	const char *indexfile = get_index_file();
e83c5163	228
bb233d69 LT	229	snprintf(lockfile, sizeof(lockfile), "%s.lock", indexfile);
	230
	231	newfd = open(lockfile, O_RDWR \| O_CREAT \| O_EXCL, 0600);
83adac3c	232	if (newfd < 0)
2de381f9	233	die("unable to create new cachefile");
9614b8dc	234	atexit(remove_lock_file);
bb233d69	235	lockfile_name = lockfile;
83adac3c	236
ca016f0e	237	merge = 0;
83adac3c LT	238	for (i = 1; i < argc; i++) {
	239	const char *arg = argv[i];
	240
d99082e0	241	/* "-m" stands for "merge", meaning we start in stage 1 */
83adac3c	242	if (!strcmp(arg, "-m")) {
ca016f0e LT	243	int i;
ca016f0e LT	244	if (stage)
c5bac17a	245	die("-m needs to come first");
ca016f0e LT	246	read_cache();
	247	for (i = 0; i < active_nr; i++) {
	248	if (ce_stage(active_cache[i]))
c5bac17a	249	die("you need to resolve your current index first");
ca016f0e	250	}
d99082e0	251	stage = 1;
ca016f0e	252	merge = 1;
83adac3c LT	253	continue;
83adac3c LT	254	}
9614b8dc	255	if (get_sha1_hex(arg, sha1) < 0)
c5bac17a	256	usage(read_tree_usage);
d99082e0	257	if (stage > 3)
c5bac17a	258	usage(read_tree_usage);
9614b8dc	259	if (read_tree(sha1, "", 0) < 0)
2de381f9	260	die("failed to unpack tree object %s", arg);
d99082e0	261	stage++;
83adac3c	262	}
ca016f0e	263	if (merge) {
a3a65234 LT	264	switch (stage) {
	265	case 4: /* Three-way merge */
	266	trivially_merge_cache(active_cache, active_nr);
	267	break;
	268	case 2: /* Just read a tree, merge with old cache contents */
	269	merge_stat_info(active_cache, active_nr);
	270	break;
	271	default:
	272	die("just how do you expect me to merge %d trees?", stage-1);
	273	}
ca016f0e	274	}
bb233d69	275	if (write_cache(newfd, active_cache, active_nr) \|\| rename(lockfile, indexfile))
2de381f9	276	die("unable to write new index file");
bb233d69	277	lockfile_name = NULL;
9614b8dc	278	return 0;
e83c5163	279	}