[thirdparty/git.git] / commit.c

#include <ctype.h>
#include "tag.h"
#include "commit.h"
#include "cache.h"

struct sort_node
{
	/*
         * the number of children of the associated commit
         * that also occur in the list being sorted.
         */
	unsigned int indegree;

	/*
         * reference to original list item that we will re-use
         * on output.
         */
	struct commit_list * list_item;

};

const char *commit_type = "commit";

enum cmit_fmt get_commit_format(const char *arg)
{
	if (!*arg)
		return CMIT_FMT_DEFAULT;
	if (!strcmp(arg, "=raw"))
		return CMIT_FMT_RAW;
	if (!strcmp(arg, "=medium"))
		return CMIT_FMT_MEDIUM;
	if (!strcmp(arg, "=short"))
		return CMIT_FMT_SHORT;
	if (!strcmp(arg, "=full"))
		return CMIT_FMT_FULL;
	die("invalid --pretty format");
}

static struct commit *check_commit(struct object *obj, const unsigned char *sha1)
{
	if (obj->type != commit_type) {
		error("Object %s is a %s, not a commit", 
		      sha1_to_hex(sha1), obj->type);
		return NULL;
	}
	return (struct commit *) obj;
}

struct commit *lookup_commit_reference(const unsigned char *sha1)
{
	struct object *obj = parse_object(sha1);

	if (!obj)
		return NULL;
	while (obj->type == tag_type)
		obj = parse_object(((struct tag *)obj)->tagged->sha1);

	return check_commit(obj, sha1);
}

struct commit *lookup_commit(const unsigned char *sha1)
{
	struct object *obj = lookup_object(sha1);
	if (!obj) {
		struct commit *ret = xmalloc(sizeof(struct commit));
		memset(ret, 0, sizeof(struct commit));
		created_object(sha1, &ret->object);
		ret->object.type = commit_type;
		return ret;
	}
	if (!obj->type)
		obj->type = commit_type;
	return check_commit(obj, sha1);
}

static unsigned long parse_commit_date(const char *buf)
{
	unsigned long date;

	if (memcmp(buf, "author", 6))
		return 0;
	while (*buf++ != '\n')
		/* nada */;
	if (memcmp(buf, "committer", 9))
		return 0;
	while (*buf++ != '>')
		/* nada */;
	date = strtoul(buf, NULL, 10);
	if (date == ULONG_MAX)
		date = 0;
	return date;
}

int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
{
	void *bufptr = buffer;
	unsigned char parent[20];
	struct commit_list **pptr;

	if (item->object.parsed)
		return 0;
	item->object.parsed = 1;
	get_sha1_hex(bufptr + 5, parent);
	item->tree = lookup_tree(parent);
	if (item->tree)
		add_ref(&item->object, &item->tree->object);
	bufptr += 46; /* "tree " + "hex sha1" + "\n" */
	pptr = &item->parents;
	while (!memcmp(bufptr, "parent ", 7) &&
	       !get_sha1_hex(bufptr + 7, parent)) {
		struct commit *new_parent = lookup_commit(parent);
		if (new_parent) {
			pptr = &commit_list_insert(new_parent, pptr)->next;
			add_ref(&item->object, &new_parent->object);
		}
		bufptr += 48;
	}
	item->date = parse_commit_date(bufptr);
	return 0;
}

int parse_commit(struct commit *item)
{
	char type[20];
	void *buffer;
	unsigned long size;
	int ret;

	if (item->object.parsed)
		return 0;
	buffer = read_sha1_file(item->object.sha1, type, &size);
	if (!buffer)
		return error("Could not read %s",
			     sha1_to_hex(item->object.sha1));
	if (strcmp(type, commit_type)) {
		free(buffer);
		return error("Object %s not a commit",
			     sha1_to_hex(item->object.sha1));
	}
	ret = parse_commit_buffer(item, buffer, size);
	if (!ret) {
		item->buffer = buffer;
		return 0;
	}
	free(buffer);
	return ret;
}

struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
{
	struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
	new_list->item = item;
	new_list->next = *list_p;
	*list_p = new_list;
	return new_list;
}

void free_commit_list(struct commit_list *list)
{
	while (list) {
		struct commit_list *temp = list;
		list = temp->next;
		free(temp);
	}
}

struct commit_list * insert_by_date(struct commit *item, struct commit_list **list)
{
	struct commit_list **pp = list;
	struct commit_list *p;
	while ((p = *pp) != NULL) {
		if (p->item->date < item->date) {
			break;
		}
		pp = &p->next;
	}
	return commit_list_insert(item, pp);
}

	
void sort_by_date(struct commit_list **list)
{
	struct commit_list *ret = NULL;
	while (*list) {
		insert_by_date((*list)->item, &ret);
		*list = (*list)->next;
	}
	*list = ret;
}

struct commit *pop_most_recent_commit(struct commit_list **list,
				      unsigned int mark)
{
	struct commit *ret = (*list)->item;
	struct commit_list *parents = ret->parents;
	struct commit_list *old = *list;

	*list = (*list)->next;
	free(old);

	while (parents) {
		struct commit *commit = parents->item;
		parse_commit(commit);
		if (!(commit->object.flags & mark)) {
			commit->object.flags |= mark;
			insert_by_date(commit, list);
		}
		parents = parents->next;
	}
	return ret;
}

/*
 * Generic support for pretty-printing the header
 */
static int get_one_line(const char *msg, unsigned long len)
{
	int ret = 0;

	while (len--) {
		char c = *msg++;
		ret++;
		if (c == '\n')
			break;
		if (!c)
			return 0;
	}
	return ret;
}

static int add_user_info(const char *what, enum cmit_fmt fmt, char *buf, const char *line)
{
	char *date;
	unsigned int namelen;
	unsigned long time;
	int tz, ret;

	date = strchr(line, '>');
	if (!date)
		return 0;
	namelen = ++date - line;
	time = strtoul(date, &date, 10);
	tz = strtol(date, NULL, 10);

	ret = sprintf(buf, "%s: %.*s\n", what, namelen, line);
	if (fmt == CMIT_FMT_MEDIUM)
		ret += sprintf(buf + ret, "Date:   %s\n", show_date(time, tz));
	return ret;
}

static int is_empty_line(const char *line, int len)
{
	while (len && isspace(line[len-1]))
		len--;
	return !len;
}

static int add_parent_info(enum cmit_fmt fmt, char *buf, const char *line, int parents)
{
	int offset = 0;
	switch (parents) {
	case 1:
		break;
	case 2:
		/* Go back to the previous line: 40 characters of previous parent, and one '\n' */
		offset = sprintf(buf, "Merge: %.40s\n", line-41);
		/* Fallthrough */
	default:
		/* Replace the previous '\n' with a space */
		buf[offset-1] = ' ';
		offset += sprintf(buf + offset, "%.40s\n", line+7);
	}
	return offset;
}

unsigned long pretty_print_commit(enum cmit_fmt fmt, const char *msg, unsigned long len, char *buf, unsigned long space)
{
	int hdr = 1, body = 0;
	unsigned long offset = 0;
	int parents = 0;

	for (;;) {
		const char *line = msg;
		int linelen = get_one_line(msg, len);

		if (!linelen)
			break;

		/*
		 * We want some slop for indentation and a possible
		 * final "...". Thus the "+ 20".
		 */
		if (offset + linelen + 20 > space) {
			memcpy(buf + offset, "    ...\n", 8);
			offset += 8;
			break;
		}

		msg += linelen;
		len -= linelen;
		if (hdr) {
			if (linelen == 1) {
				hdr = 0;
				buf[offset++] = '\n';
				continue;
			}
			if (fmt == CMIT_FMT_RAW) {
				memcpy(buf + offset, line, linelen);
				offset += linelen;
				continue;
			}
			if (!memcmp(line, "parent ", 7)) {
				if (linelen != 48)
					die("bad parent line in commit");
				offset += add_parent_info(fmt, buf + offset, line, ++parents);
			}
			if (!memcmp(line, "author ", 7))
				offset += add_user_info("Author", fmt, buf + offset, line + 7);
			if (fmt == CMIT_FMT_FULL) {
				if (!memcmp(line, "committer ", 10))
					offset += add_user_info("Commit", fmt, buf + offset, line + 10);
			}
			continue;
		}

		if (is_empty_line(line, linelen)) {
			if (!body)
				continue;
			if (fmt == CMIT_FMT_SHORT)
				break;
		} else {
			body = 1;
		}
		memset(buf + offset, ' ', 4);
		memcpy(buf + offset + 4, line, linelen);
		offset += linelen + 4;
	}
	/* Make sure there is an EOLN */
	if (buf[offset - 1] != '\n')
		buf[offset++] = '\n';
	buf[offset] = '\0';
	return offset;
}

struct commit *pop_commit(struct commit_list **stack)
{
	struct commit_list *top = *stack;
	struct commit *item = top ? top->item : NULL;

	if (top) {
		*stack = top->next;
		free(top);
	}
	return item;
}

int count_parents(struct commit * commit)
{
        int count = 0;
        struct commit_list * parents = commit->parents;
        for (count=0;parents; parents=parents->next,count++)
          ;
        return count;
}

/*
 * Performs an in-place topological sort on the list supplied.
 */
void sort_in_topological_order(struct commit_list ** list)
{
	struct commit_list * next = *list;
	struct commit_list * work = NULL;
	struct commit_list ** pptr = list;
	struct sort_node * nodes;
	struct sort_node * next_nodes;
	int count = 0;

	/* determine the size of the list */
	while (next) {
		next = next->next;
		count++;
	}
	/* allocate an array to help sort the list */
	nodes = xcalloc(count, sizeof(*nodes));
	/* link the list to the array */
	next_nodes = nodes;
	next=*list;
	while (next) {
		next_nodes->list_item = next;
		next->item->object.util = next_nodes;
		next_nodes++;
		next = next->next;
	}
	/* update the indegree */
	next=*list;
	while (next) {
		struct commit_list * parents = next->item->parents;
		while (parents) {
			struct commit * parent=parents->item;
			struct sort_node * pn = (struct sort_node *)parent->object.util;
			
			if (pn)
				pn->indegree++;
			parents=parents->next;
		}
		next=next->next;
	}
	/* 
         * find the tips
         *
         * tips are nodes not reachable from any other node in the list 
         * 
         * the tips serve as a starting set for the work queue.
         */
	next=*list;
	while (next) {
		struct sort_node * node = (struct sort_node *)next->item->object.util;

		if (node->indegree == 0) {
			commit_list_insert(next->item, &work);
		}
		next=next->next;
	}
	/* process the list in topological order */
	while (work) {
		struct commit * work_item = pop_commit(&work);
		struct sort_node * work_node = (struct sort_node *)work_item->object.util;
		struct commit_list * parents = work_item->parents;

		while (parents) {
			struct commit * parent=parents->item;
			struct sort_node * pn = (struct sort_node *)parent->object.util;
			
			if (pn) {
				/* 
				 * parents are only enqueued for emission 
                                 * when all their children have been emitted thereby
                                 * guaranteeing topological order.
                                 */
				pn->indegree--;
				if (!pn->indegree) 
					commit_list_insert(parent, &work);
			}
			parents=parents->next;
		}
		/*
                 * work_item is a commit all of whose children
                 * have already been emitted. we can emit it now.
                 */
		*pptr = work_node->list_item;
		pptr = &(*pptr)->next;
		*pptr = NULL;
		work_item->object.util = NULL;
	}
	free(nodes);
}
Commit	Line	Data
000182ea	1	#include <ctype.h>
961784ee	2	#include "tag.h"
175785e5 DB	3	#include "commit.h"
175785e5 DB	4	#include "cache.h"
175785e5	5
ab580ace JS	6	struct sort_node
	7	{
	8	/*
	9	* the number of children of the associated commit
	10	* that also occur in the list being sorted.
	11	*/
	12	unsigned int indegree;
	13
	14	/*
	15	* reference to original list item that we will re-use
	16	* on output.
	17	*/
	18	struct commit_list * list_item;
	19
	20	};
	21
175785e5 DB	22	const char *commit_type = "commit";
175785e5 DB	23
9b66ec04 LT	24	enum cmit_fmt get_commit_format(const char *arg)
	25	{
	26	if (!*arg)
	27	return CMIT_FMT_DEFAULT;
	28	if (!strcmp(arg, "=raw"))
	29	return CMIT_FMT_RAW;
	30	if (!strcmp(arg, "=medium"))
	31	return CMIT_FMT_MEDIUM;
	32	if (!strcmp(arg, "=short"))
	33	return CMIT_FMT_SHORT;
	34	if (!strcmp(arg, "=full"))
	35	return CMIT_FMT_FULL;
	36	die("invalid --pretty format");
	37	}
	38
5d6ccf5c	39	static struct commit check_commit(struct object obj, const unsigned char *sha1)
961784ee LT	40	{
	41	if (obj->type != commit_type) {
	42	error("Object %s is a %s, not a commit",
	43	sha1_to_hex(sha1), obj->type);
	44	return NULL;
	45	}
	46	return (struct commit *) obj;
	47	}
	48
5d6ccf5c	49	struct commit lookup_commit_reference(const unsigned char sha1)
961784ee LT	50	{
	51	struct object *obj = parse_object(sha1);
	52
	53	if (!obj)
	54	return NULL;
013aab82 JH	55	while (obj->type == tag_type)
	56	obj = parse_object(((struct tag *)obj)->tagged->sha1);
	57
961784ee LT	58	return check_commit(obj, sha1);
	59	}
	60
5d6ccf5c	61	struct commit lookup_commit(const unsigned char sha1)
175785e5 DB	62	{
	63	struct object *obj = lookup_object(sha1);
	64	if (!obj) {
812666c8	65	struct commit *ret = xmalloc(sizeof(struct commit));
175785e5 DB	66	memset(ret, 0, sizeof(struct commit));
175785e5 DB	67	created_object(sha1, &ret->object);
d32987be	68	ret->object.type = commit_type;
175785e5 DB	69	return ret;
175785e5 DB	70	}
d1af002d NP	71	if (!obj->type)
d1af002d NP	72	obj->type = commit_type;
961784ee	73	return check_commit(obj, sha1);
175785e5 DB	74	}
	75
	76	static unsigned long parse_commit_date(const char *buf)
	77	{
	78	unsigned long date;
	79
	80	if (memcmp(buf, "author", 6))
	81	return 0;
	82	while (*buf++ != '\n')
	83	/* nada */;
	84	if (memcmp(buf, "committer", 9))
	85	return 0;
	86	while (*buf++ != '>')
	87	/* nada */;
	88	date = strtoul(buf, NULL, 10);
	89	if (date == ULONG_MAX)
	90	date = 0;
	91	return date;
	92	}
	93
bd2c39f5	94	int parse_commit_buffer(struct commit item, void buffer, unsigned long size)
175785e5	95	{
bd2c39f5	96	void *bufptr = buffer;
175785e5	97	unsigned char parent[20];
6c88be16	98	struct commit_list **pptr;
bd2c39f5	99
175785e5 DB	100	if (item->object.parsed)
	101	return 0;
	102	item->object.parsed = 1;
175785e5 DB	103	get_sha1_hex(bufptr + 5, parent);
175785e5 DB	104	item->tree = lookup_tree(parent);
235ac407 LT	105	if (item->tree)
235ac407 LT	106	add_ref(&item->object, &item->tree->object);
175785e5	107	bufptr += 46; /* "tree " + "hex sha1" + "\n" */
6c88be16	108	pptr = &item->parents;
175785e5 DB	109	while (!memcmp(bufptr, "parent ", 7) &&
175785e5 DB	110	!get_sha1_hex(bufptr + 7, parent)) {
dd97f850	111	struct commit *new_parent = lookup_commit(parent);
235ac407	112	if (new_parent) {
6c88be16	113	pptr = &commit_list_insert(new_parent, pptr)->next;
235ac407 LT	114	add_ref(&item->object, &new_parent->object);
235ac407 LT	115	}
175785e5 DB	116	bufptr += 48;
	117	}
	118	item->date = parse_commit_date(bufptr);
175785e5 DB	119	return 0;
	120	}
	121
bd2c39f5 NP	122	int parse_commit(struct commit *item)
	123	{
	124	char type[20];
	125	void *buffer;
	126	unsigned long size;
	127	int ret;
	128
	129	if (item->object.parsed)
	130	return 0;
	131	buffer = read_sha1_file(item->object.sha1, type, &size);
	132	if (!buffer)
	133	return error("Could not read %s",
	134	sha1_to_hex(item->object.sha1));
	135	if (strcmp(type, commit_type)) {
	136	free(buffer);
	137	return error("Object %s not a commit",
	138	sha1_to_hex(item->object.sha1));
	139	}
	140	ret = parse_commit_buffer(item, buffer, size);
3ff1fbbb LT	141	if (!ret) {
	142	item->buffer = buffer;
	143	return 0;
	144	}
bd2c39f5 NP	145	free(buffer);
	146	return ret;
	147	}
	148
ac5155ef	149	struct commit_list commit_list_insert(struct commit item, struct commit_list **list_p)
dd97f850	150	{
812666c8	151	struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
dd97f850 DB	152	new_list->item = item;
	153	new_list->next = *list_p;
	154	*list_p = new_list;
ac5155ef	155	return new_list;
dd97f850 DB	156	}
dd97f850 DB	157
175785e5 DB	158	void free_commit_list(struct commit_list *list)
	159	{
	160	while (list) {
	161	struct commit_list *temp = list;
	162	list = temp->next;
	163	free(temp);
	164	}
	165	}
dd97f850	166
f755494c	167	struct commit_list * insert_by_date(struct commit item, struct commit_list *list)
dd97f850 DB	168	{
	169	struct commit_list **pp = list;
	170	struct commit_list *p;
	171	while ((p = *pp) != NULL) {
	172	if (p->item->date < item->date) {
	173	break;
	174	}
	175	pp = &p->next;
	176	}
f755494c	177	return commit_list_insert(item, pp);
dd97f850 DB	178	}
	179
	180
	181	void sort_by_date(struct commit_list **list)
	182	{
	183	struct commit_list *ret = NULL;
	184	while (*list) {
f755494c	185	insert_by_date((*list)->item, &ret);
dd97f850 DB	186	list = (list)->next;
	187	}
	188	*list = ret;
	189	}
	190
58e28af6 DB	191	struct commit pop_most_recent_commit(struct commit_list *list,
58e28af6 DB	192	unsigned int mark)
dd97f850 DB	193	{
	194	struct commit ret = (list)->item;
	195	struct commit_list *parents = ret->parents;
	196	struct commit_list old = list;
	197
	198	list = (list)->next;
	199	free(old);
	200
	201	while (parents) {
4056c091	202	struct commit *commit = parents->item;
58e28af6 DB	203	parse_commit(commit);
	204	if (!(commit->object.flags & mark)) {
	205	commit->object.flags \|= mark;
f755494c	206	insert_by_date(commit, list);
4056c091	207	}
dd97f850 DB	208	parents = parents->next;
	209	}
	210	return ret;
	211	}
e3bc7a3b LT	212
	213	/*
	214	* Generic support for pretty-printing the header
	215	*/
	216	static int get_one_line(const char *msg, unsigned long len)
	217	{
	218	int ret = 0;
	219
	220	while (len--) {
	221	char c = *msg++;
	222	ret++;
	223	if (c == '\n')
	224	break;
	225	if (!c)
	226	return 0;
	227	}
	228	return ret;
	229	}
	230
9b66ec04	231	static int add_user_info(const char what, enum cmit_fmt fmt, char buf, const char *line)
e3bc7a3b LT	232	{
	233	char *date;
	234	unsigned int namelen;
	235	unsigned long time;
000182ea	236	int tz, ret;
e3bc7a3b	237
e3bc7a3b LT	238	date = strchr(line, '>');
	239	if (!date)
	240	return 0;
	241	namelen = ++date - line;
	242	time = strtoul(date, &date, 10);
	243	tz = strtol(date, NULL, 10);
	244
9b66ec04	245	ret = sprintf(buf, "%s: %.*s\n", what, namelen, line);
000182ea LT	246	if (fmt == CMIT_FMT_MEDIUM)
	247	ret += sprintf(buf + ret, "Date: %s\n", show_date(time, tz));
	248	return ret;
	249	}
	250
	251	static int is_empty_line(const char *line, int len)
	252	{
	253	while (len && isspace(line[len-1]))
	254	len--;
	255	return !len;
e3bc7a3b LT	256	}
e3bc7a3b LT	257
28342a5d LT	258	static int add_parent_info(enum cmit_fmt fmt, char buf, const char line, int parents)
	259	{
	260	int offset = 0;
	261	switch (parents) {
	262	case 1:
	263	break;
	264	case 2:
	265	/* Go back to the previous line: 40 characters of previous parent, and one '\n' */
	266	offset = sprintf(buf, "Merge: %.40s\n", line-41);
	267	/* Fallthrough */
	268	default:
	269	/* Replace the previous '\n' with a space */
	270	buf[offset-1] = ' ';
	271	offset += sprintf(buf + offset, "%.40s\n", line+7);
	272	}
	273	return offset;
	274	}
	275
000182ea	276	unsigned long pretty_print_commit(enum cmit_fmt fmt, const char msg, unsigned long len, char buf, unsigned long space)
e3bc7a3b	277	{
000182ea	278	int hdr = 1, body = 0;
e3bc7a3b	279	unsigned long offset = 0;
28342a5d	280	int parents = 0;
e3bc7a3b LT	281
	282	for (;;) {
	283	const char *line = msg;
	284	int linelen = get_one_line(msg, len);
	285
	286	if (!linelen)
	287	break;
	288
	289	/*
	290	* We want some slop for indentation and a possible
	291	* final "...". Thus the "+ 20".
	292	*/
	293	if (offset + linelen + 20 > space) {
	294	memcpy(buf + offset, " ...\n", 8);
	295	offset += 8;
	296	break;
	297	}
	298
	299	msg += linelen;
	300	len -= linelen;
e3bc7a3b	301	if (hdr) {
000182ea LT	302	if (linelen == 1) {
	303	hdr = 0;
	304	buf[offset++] = '\n';
	305	continue;
	306	}
	307	if (fmt == CMIT_FMT_RAW) {
	308	memcpy(buf + offset, line, linelen);
	309	offset += linelen;
	310	continue;
	311	}
28342a5d LT	312	if (!memcmp(line, "parent ", 7)) {
	313	if (linelen != 48)
	314	die("bad parent line in commit");
	315	offset += add_parent_info(fmt, buf + offset, line, ++parents);
	316	}
e3bc7a3b	317	if (!memcmp(line, "author ", 7))
9b66ec04 LT	318	offset += add_user_info("Author", fmt, buf + offset, line + 7);
	319	if (fmt == CMIT_FMT_FULL) {
	320	if (!memcmp(line, "committer ", 10))
	321	offset += add_user_info("Commit", fmt, buf + offset, line + 10);
	322	}
e3bc7a3b LT	323	continue;
e3bc7a3b LT	324	}
000182ea LT	325
	326	if (is_empty_line(line, linelen)) {
	327	if (!body)
	328	continue;
	329	if (fmt == CMIT_FMT_SHORT)
	330	break;
	331	} else {
	332	body = 1;
	333	}
e3bc7a3b LT	334	memset(buf + offset, ' ', 4);
	335	memcpy(buf + offset + 4, line, linelen);
	336	offset += linelen + 4;
	337	}
	338	/* Make sure there is an EOLN */
	339	if (buf[offset - 1] != '\n')
	340	buf[offset++] = '\n';
	341	buf[offset] = '\0';
	342	return offset;
	343	}
a3437b8c JS	344
	345	struct commit pop_commit(struct commit_list *stack)
	346	{
	347	struct commit_list top = stack;
	348	struct commit *item = top ? top->item : NULL;
	349
	350	if (top) {
	351	*stack = top->next;
	352	free(top);
	353	}
	354	return item;
	355	}
	356
	357	int count_parents(struct commit * commit)
	358	{
	359	int count = 0;
	360	struct commit_list * parents = commit->parents;
	361	for (count=0;parents; parents=parents->next,count++)
	362	;
	363	return count;
	364	}
	365
ab580ace JS	366	/*
	367	* Performs an in-place topological sort on the list supplied.
	368	*/
	369	void sort_in_topological_order(struct commit_list ** list)
	370	{
	371	struct commit_list * next = *list;
	372	struct commit_list * work = NULL;
	373	struct commit_list ** pptr = list;
	374	struct sort_node * nodes;
	375	struct sort_node * next_nodes;
	376	int count = 0;
	377
	378	/* determine the size of the list */
	379	while (next) {
	380	next = next->next;
	381	count++;
	382	}
	383	/* allocate an array to help sort the list */
	384	nodes = xcalloc(count, sizeof(*nodes));
	385	/* link the list to the array */
	386	next_nodes = nodes;
	387	next=*list;
	388	while (next) {
	389	next_nodes->list_item = next;
	390	next->item->object.util = next_nodes;
	391	next_nodes++;
	392	next = next->next;
	393	}
	394	/* update the indegree */
	395	next=*list;
	396	while (next) {
	397	struct commit_list * parents = next->item->parents;
	398	while (parents) {
	399	struct commit * parent=parents->item;
	400	struct sort_node * pn = (struct sort_node *)parent->object.util;
	401
	402	if (pn)
	403	pn->indegree++;
	404	parents=parents->next;
	405	}
	406	next=next->next;
	407	}
	408	/*
	409	* find the tips
	410	*
	411	* tips are nodes not reachable from any other node in the list
	412	*
	413	* the tips serve as a starting set for the work queue.
	414	*/
	415	next=*list;
	416	while (next) {
	417	struct sort_node * node = (struct sort_node *)next->item->object.util;
	418
	419	if (node->indegree == 0) {
	420	commit_list_insert(next->item, &work);
	421	}
	422	next=next->next;
	423	}
	424	/* process the list in topological order */
	425	while (work) {
	426	struct commit * work_item = pop_commit(&work);
	427	struct sort_node * work_node = (struct sort_node *)work_item->object.util;
	428	struct commit_list * parents = work_item->parents;
	429
430	while (parents) {
431	struct commit * parent=parents->item;
432	struct sort_node * pn = (struct sort_node *)parent->object.util;
433
434	if (pn) {
435	/*
436	* parents are only enqueued for emission
437	* when all their children have been emitted thereby
438	* guaranteeing topological order.
439	*/
440	pn->indegree--;
441	if (!pn->indegree)
442	commit_list_insert(parent, &work);
443	}
444	parents=parents->next;
445	}
446	/*
447	* work_item is a commit all of whose children
448	* have already been emitted. we can emit it now.
449	*/
450	*pptr = work_node->list_item;
451	pptr = &(*pptr)->next;
452	*pptr = NULL;
453	work_item->object.util = NULL;
454	}
455	free(nodes);
456	}