[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, unsigned long size,
			       const char *base, int baselen)
{
	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 || strcmp(elttype, "tree"))
				return -1;
			memcpy(newbase, base, baselen);
			memcpy(newbase + baselen, path, pathlen);
			newbase[baselen + pathlen] = '/';
			retval = read_tree_recursive(eltbuf, 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);
	if (!buffer)
		return -1;
	return read_tree_recursive(buffer, 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
aba06682	26	static int read_tree_recursive(void *buffer, unsigned long size,
b12ec373	27	const char *base, int baselen)
e83c5163	28	{
e83c5163 LT	29	while (size) {
	30	int len = strlen(buffer)+1;
	31	unsigned char *sha1 = buffer + len;
	32	char *path = strchr(buffer, ' ')+1;
	33	unsigned int mode;
e497ea2a	34
e83c5163	35	if (size < len + 20 \|\| sscanf(buffer, "%o", &mode) != 1)
83adac3c LT	36	return -1;
83adac3c LT	37
e83c5163 LT	38	buffer = sha1 + 20;
e83c5163 LT	39	size -= len + 20;
83adac3c	40
f768846e LT	41	if (S_ISDIR(mode)) {
	42	int retval;
	43	int pathlen = strlen(path);
	44	char *newbase = malloc(baselen + 1 + pathlen);
b12ec373 JH	45	void *eltbuf;
	46	char elttype[20];
	47	unsigned long eltsize;
	48
	49	eltbuf = read_sha1_file(sha1, elttype, &eltsize);
aba06682	50	if (!eltbuf \|\| strcmp(elttype, "tree"))
b12ec373	51	return -1;
f768846e LT	52	memcpy(newbase, base, baselen);
	53	memcpy(newbase + baselen, path, pathlen);
	54	newbase[baselen + pathlen] = '/';
aba06682	55	retval = read_tree_recursive(eltbuf, eltsize,
b12ec373 JH	56	newbase,
	57	baselen + pathlen + 1);
	58	free(eltbuf);
f768846e LT	59	free(newbase);
	60	if (retval)
	61	return -1;
	62	continue;
	63	}
	64	if (read_one_entry(sha1, base, baselen, path, mode) < 0)
83adac3c	65	return -1;
e83c5163 LT	66	}
	67	return 0;
	68	}
	69
b12ec373 JH	70	static int read_tree(unsigned char sha1, const char base, int baselen)
	71	{
	72	void *buffer;
	73	unsigned long size;
	74
	75	buffer = read_tree_with_tree_or_commit_sha1(sha1, &size, 0);
aba06682 LT	76	if (!buffer)
	77	return -1;
	78	return read_tree_recursive(buffer, size, base, baselen);
b12ec373 JH	79	}
b12ec373 JH	80
bb233d69	81	static char *lockfile_name;
9614b8dc LT	82
	83	static void remove_lock_file(void)
	84	{
bb233d69 LT	85	if (lockfile_name)
bb233d69 LT	86	unlink(lockfile_name);
9614b8dc LT	87	}
9614b8dc LT	88
ca016f0e LT	89	static int path_matches(struct cache_entry a, struct cache_entry b)
	90	{
	91	int len = ce_namelen(a);
	92	return ce_namelen(b) == len &&
	93	!memcmp(a->name, b->name, len);
	94	}
	95
43f91266 LT	96	static int same(struct cache_entry a, struct cache_entry b)
	97	{
	98	return a->ce_mode == b->ce_mode &&
	99	!memcmp(a->sha1, b->sha1, 20);
	100	}
	101
	102
d99082e0	103	/*
43f91266 LT	104	* This removes all trivial merges that don't change the tree
43f91266 LT	105	* and collapses them to state 0.
d99082e0	106	*
43f91266 LT	107	* _Any_ other merge is left to user policy. That includes "both
	108	* created the same file", and "both removed the same file" - which are
	109	* trivial, but the user might still want to _note_ it.
d99082e0	110	*/
43f91266 LT	111	static struct cache_entry merge_entries(struct cache_entry a,
	112	struct cache_entry *b,
	113	struct cache_entry *c)
d99082e0 LT	114	{
d99082e0 LT	115	int len = ce_namelen(a);
43f91266 LT	116
	117	/*
	118	* Are they all the same filename? We won't do
	119	* any name merging
	120	*/
	121	if (ce_namelen(b) != len \|\|
	122	ce_namelen(c) != len \|\|
	123	memcmp(a->name, b->name, len) \|\|
	124	memcmp(a->name, c->name, len))
	125	return NULL;
	126
	127	/*
	128	* Ok, all three entries describe the same
	129	* filename, but maybe the contents or file
	130	* mode have changed?
	131	*
	132	* The trivial cases end up being the ones where two
	133	* out of three files are the same:
	134	* - both destinations the same, trivially take either
	135	* - one of the destination versions hasn't changed,
	136	* take the other.
	137	*
	138	* The "all entries exactly the same" case falls out as
	139	* a special case of any of the "two same" cases.
	140	*
	141	* Here "a" is "original", and "b" and "c" are the two
	142	* trees we are merging.
	143	*/
	144	if (same(b,c))
	145	return c;
	146	if (same(a,b))
	147	return c;
	148	if (same(a,c))
	149	return b;
	150	return NULL;
d99082e0 LT	151	}
	152
	153	static void trivially_merge_cache(struct cache_entry **src, int nr)
	154	{
ca016f0e	155	static struct cache_entry null_entry;
d99082e0	156	struct cache_entry **dst = src;
ca016f0e	157	struct cache_entry *old = &null_entry;
d99082e0 LT	158
d99082e0 LT	159	while (nr) {
43f91266	160	struct cache_entry ce, result;
d99082e0 LT	161
d99082e0 LT	162	ce = src[0];
ca016f0e LT	163
	164	/* We throw away original cache entries except for the stat information */
	165	if (!ce_stage(ce)) {
	166	old = ce;
	167	src++;
	168	nr--;
	169	active_nr--;
	170	continue;
	171	}
43f91266	172	if (nr > 2 && (result = merge_entries(ce, src[1], src[2])) != NULL) {
ca016f0e LT	173	/*
	174	* See if we can re-use the old CE directly?
	175	* That way we get the uptodate stat info.
	176	*/
	177	if (path_matches(result, old) && same(result, old))
	178	result = old;
43f91266	179	ce = result;
d99082e0 LT	180	ce->ce_flags &= ~htons(CE_STAGEMASK);
	181	src += 2;
	182	nr -= 2;
	183	active_nr -= 2;
	184	}
a3a65234 LT	185	*dst++ = ce;
	186	src++;
	187	nr--;
	188	}
	189	}
	190
	191	static void merge_stat_info(struct cache_entry **src, int nr)
	192	{
	193	static struct cache_entry null_entry;
	194	struct cache_entry **dst = src;
	195	struct cache_entry *old = &null_entry;
	196
	197	while (nr) {
	198	struct cache_entry *ce;
	199
	200	ce = src[0];
	201
	202	/* We throw away original cache entries except for the stat information */
	203	if (!ce_stage(ce)) {
	204	old = ce;
	205	src++;
	206	nr--;
	207	active_nr--;
	208	continue;
	209	}
	210	if (path_matches(ce, old) && same(ce, old))
	211	ce = old;
	212	ce->ce_flags &= ~htons(CE_STAGEMASK);
	213	*dst++ = ce;
d99082e0	214	src++;
d99082e0 LT	215	nr--;
	216	}
	217	}
	218
c5bac17a JH	219	static char *read_tree_usage = "read-tree (<sha> \| -m <sha1> [<sha2> <sha3>])";
c5bac17a JH	220
e83c5163 LT	221	int main(int argc, char **argv)
e83c5163 LT	222	{
ca016f0e	223	int i, newfd, merge;
e83c5163	224	unsigned char sha1[20];
bb233d69 LT	225	static char lockfile[MAXPATHLEN+1];
bb233d69 LT	226	const char *indexfile = get_index_file();
e83c5163	227
bb233d69 LT	228	snprintf(lockfile, sizeof(lockfile), "%s.lock", indexfile);
	229
	230	newfd = open(lockfile, O_RDWR \| O_CREAT \| O_EXCL, 0600);
83adac3c	231	if (newfd < 0)
2de381f9	232	die("unable to create new cachefile");
9614b8dc	233	atexit(remove_lock_file);
bb233d69	234	lockfile_name = lockfile;
83adac3c	235
ca016f0e	236	merge = 0;
83adac3c LT	237	for (i = 1; i < argc; i++) {
	238	const char *arg = argv[i];
	239
d99082e0	240	/* "-m" stands for "merge", meaning we start in stage 1 */
83adac3c	241	if (!strcmp(arg, "-m")) {
ca016f0e LT	242	int i;
ca016f0e LT	243	if (stage)
c5bac17a	244	die("-m needs to come first");
ca016f0e LT	245	read_cache();
	246	for (i = 0; i < active_nr; i++) {
	247	if (ce_stage(active_cache[i]))
c5bac17a	248	die("you need to resolve your current index first");
ca016f0e	249	}
d99082e0	250	stage = 1;
ca016f0e	251	merge = 1;
83adac3c LT	252	continue;
83adac3c LT	253	}
9614b8dc	254	if (get_sha1_hex(arg, sha1) < 0)
c5bac17a	255	usage(read_tree_usage);
d99082e0	256	if (stage > 3)
c5bac17a	257	usage(read_tree_usage);
9614b8dc	258	if (read_tree(sha1, "", 0) < 0)
2de381f9	259	die("failed to unpack tree object %s", arg);
d99082e0	260	stage++;
83adac3c	261	}
ca016f0e	262	if (merge) {
a3a65234 LT	263	switch (stage) {
	264	case 4: /* Three-way merge */
	265	trivially_merge_cache(active_cache, active_nr);
	266	break;
	267	case 2: /* Just read a tree, merge with old cache contents */
	268	merge_stat_info(active_cache, active_nr);
	269	break;
	270	default:
	271	die("just how do you expect me to merge %d trees?", stage-1);
	272	}
ca016f0e	273	}
bb233d69	274	if (write_cache(newfd, active_cache, active_nr) \|\| rename(lockfile, indexfile))
2de381f9	275	die("unable to write new index file");
bb233d69	276	lockfile_name = NULL;
9614b8dc	277	return 0;
e83c5163	278	}