Merge lt/revlist,jc/diff,jc/revparse,jc/abbrev

Documentation/git-rev-list.txt

@@ -14,6 +14,7 @@ SYNOPSIS
 	     [ \--min-age=timestamp ]
 	     [ \--sparse ]
 	     [ \--no-merges ]
+	     [ \--remove-empty ]
 	     [ \--all ]
 	     [ [ \--merge-order [ \--show-breaks ] ] | [ \--topo-order ] ]
 	     [ \--parents ]
@@ -80,6 +81,9 @@ OPTIONS
 	(still subject to count and age limitation), but apply
 	merge simplification nevertheless.
 
+--remove-empty::
+	Stop when a given path disappears from the tree.
+
 --all::
 	Pretend as if all the refs in `$GIT_DIR/refs/` are
 	listed on the command line as <commit>.

Makefile

@@ -182,7 +182,7 @@ LIB_H = \
 
 DIFF_OBJS = \
 	diff.o diffcore-break.o diffcore-order.o diffcore-pathspec.o \
-	diffcore-pickaxe.o diffcore-rename.o tree-diff.o
+	diffcore-pickaxe.o diffcore-rename.o tree-diff.o combine-diff.o
 
 LIB_OBJS = \
 	blob.o commit.o connect.o count-delta.o csum-file.o \

cache.h

@@ -221,6 +221,9 @@ extern int has_pack_file(const unsigned char *sha1);
 extern int has_pack_index(const unsigned char *sha1);
 
 /* Convert to/from hex/sha1 representation */
+#define MINIMUM_ABBREV 4
+#define DEFAULT_ABBREV 7
+
 extern int get_sha1(const char *str, unsigned char *sha1);
 extern int get_sha1_hex(const char *hex, unsigned char *sha1);
 extern char *sha1_to_hex(const unsigned char *sha1);	/* static buffer result! */

combine-diff.c

@@ -0,0 +1,688 @@
+#include "cache.h"
+#include "commit.h"
+#include "diff.h"
+#include "diffcore.h"
+#include "quote.h"
+
+static int uninteresting(struct diff_filepair *p)
+{
+	if (diff_unmodified_pair(p))
+		return 1;
+	if (!S_ISREG(p->one->mode) || !S_ISREG(p->two->mode))
+		return 1;
+	return 0;
+}
+
+static struct combine_diff_path *intersect_paths(struct combine_diff_path *curr, int n, int num_parent)
+{
+	struct diff_queue_struct *q = &diff_queued_diff;
+	struct combine_diff_path *p;
+	int i;
+
+	if (!n) {
+		struct combine_diff_path *list = NULL, **tail = &list;
+		for (i = 0; i < q->nr; i++) {
+			int len;
+			const char *path;
+			if (uninteresting(q->queue[i]))
+				continue;
+			path = q->queue[i]->two->path;
+			len = strlen(path);
+
+			p = xmalloc(sizeof(*p) + len + 1 + num_parent * 20);
+			p->path = (char*) &(p->parent_sha1[num_parent][0]);
+			memcpy(p->path, path, len);
+			p->path[len] = 0;
+			p->len = len;
+			p->next = NULL;
+			memcpy(p->sha1, q->queue[i]->two->sha1, 20);
+			memcpy(p->parent_sha1[n], q->queue[i]->one->sha1, 20);
+			*tail = p;
+			tail = &p->next;
+		}
+		return list;
+	}
+
+	for (p = curr; p; p = p->next) {
+		int found = 0;
+		if (!p->len)
+			continue;
+		for (i = 0; i < q->nr; i++) {
+			const char *path;
+			int len;
+
+			if (uninteresting(q->queue[i]))
+				continue;
+			path = q->queue[i]->two->path;
+			len = strlen(path);
+			if (len == p->len && !memcmp(path, p->path, len)) {
+				found = 1;
+				memcpy(p->parent_sha1[n],
+				       q->queue[i]->one->sha1, 20);
+				break;
+			}
+		}
+		if (!found)
+			p->len = 0;
+	}
+	return curr;
+}
+
+struct lline {
+	struct lline *next;
+	int len;
+	unsigned long parent_map;
+	char line[FLEX_ARRAY];
+};
+
+struct sline {
+	struct lline *lost_head, **lost_tail;
+	char *bol;
+	int len;
+	unsigned long flag;
+};
+
+static char *grab_blob(const unsigned char *sha1, unsigned long *size)
+{
+	char *blob;
+	char type[20];
+	if (!memcmp(sha1, null_sha1, 20)) {
+		/* deleted blob */
+		*size = 0;
+		return xcalloc(1, 1);
+	}
+	blob = read_sha1_file(sha1, type, size);
+	if (strcmp(type, "blob"))
+		die("object '%s' is not a blob!", sha1_to_hex(sha1));
+	return blob;
+}
+
+#define TMPPATHLEN 50
+#define MAXLINELEN 10240
+
+static void write_to_temp_file(char *tmpfile, void *blob, unsigned long size)
+{
+	int fd = git_mkstemp(tmpfile, TMPPATHLEN, ".diff_XXXXXX");
+	if (fd < 0)
+		die("unable to create temp-file");
+	if (write(fd, blob, size) != size)
+		die("unable to write temp-file");
+	close(fd);
+}
+
+static void write_temp_blob(char *tmpfile, const unsigned char *sha1)
+{
+	unsigned long size;
+	void *blob;
+	blob = grab_blob(sha1, &size);
+	write_to_temp_file(tmpfile, blob, size);
+	free(blob);
+}
+
+static int parse_num(char **cp_p, unsigned int *num_p)
+{
+	char *cp = *cp_p;
+	unsigned int num = 0;
+	int read_some;
+
+	while ('0' <= *cp && *cp <= '9')
+		num = num * 10 + *cp++ - '0';
+	if (!(read_some = cp - *cp_p))
+		return -1;
+	*cp_p = cp;
+	*num_p = num;
+	return 0;
+}
+
+static int parse_hunk_header(char *line, int len,
+			     unsigned int *ob, unsigned int *on,
+			     unsigned int *nb, unsigned int *nn)
+{
+	char *cp;
+	cp = line + 4;
+	if (parse_num(&cp, ob)) {
+	bad_line:
+		return error("malformed diff output: %s", line);
+	}
+	if (*cp == ',') {
+		cp++;
+		if (parse_num(&cp, on))
+			goto bad_line;
+	}
+	else
+		*on = 1;
+	if (*cp++ != ' ' || *cp++ != '+')
+		goto bad_line;
+	if (parse_num(&cp, nb))
+		goto bad_line;
+	if (*cp == ',') {
+		cp++;
+		if (parse_num(&cp, nn))
+			goto bad_line;
+	}
+	else
+		*nn = 1;
+	return -!!memcmp(cp, " @@", 3);
+}
+
+static void append_lost(struct sline *sline, int n, const char *line)
+{
+	struct lline *lline;
+	int len = strlen(line);
+	unsigned long this_mask = (1UL<<n);
+	if (line[len-1] == '\n')
+		len--;
+
+	/* Check to see if we can squash things */
+	if (sline->lost_head) {
+		struct lline *last_one = NULL;
+		/* We cannot squash it with earlier one */
+		for (lline = sline->lost_head;
+		     lline;
+		     lline = lline->next)
+			if (lline->parent_map & this_mask)
+				last_one = lline;
+		lline = last_one ? last_one->next : sline->lost_head;
+		while (lline) {
+			if (lline->len == len &&
+			    !memcmp(lline->line, line, len)) {
+				lline->parent_map |= this_mask;
+				return;
+			}
+			lline = lline->next;
+		}
+	}
+
+	lline = xmalloc(sizeof(*lline) + len + 1);
+	lline->len = len;
+	lline->next = NULL;
+	lline->parent_map = this_mask;
+	memcpy(lline->line, line, len);
+	lline->line[len] = 0;
+	*sline->lost_tail = lline;
+	sline->lost_tail = &lline->next;
+}
+
+static void combine_diff(const unsigned char *parent, const char *ourtmp,
+			 struct sline *sline, int cnt, int n)
+{
+	FILE *in;
+	char parent_tmp[TMPPATHLEN];
+	char cmd[TMPPATHLEN * 2 + 1024];
+	char line[MAXLINELEN];
+	unsigned int lno, ob, on, nb, nn;
+	unsigned long pmask = ~(1UL << n);
+	struct sline *lost_bucket = NULL;
+
+	write_temp_blob(parent_tmp, parent);
+	sprintf(cmd, "diff --unified=0 -La/x -Lb/x '%s' '%s'",
+		parent_tmp, ourtmp);
+	in = popen(cmd, "r");
+	if (!in)
+		return;
+
+	lno = 1;
+	while (fgets(line, sizeof(line), in) != NULL) {
+		int len = strlen(line);
+		if (5 < len && !memcmp("@@ -", line, 4)) {
+			if (parse_hunk_header(line, len,
+					      &ob, &on, &nb, &nn))
+				break;
+			lno = nb;
+			if (!nb) {
+				/* @@ -1,2 +0,0 @@ to remove the
+				 * first two lines...
+				 */
+				nb = 1;
+			}
+			lost_bucket = &sline[nb-1]; /* sline is 0 based */
+			continue;
+		}
+		if (!lost_bucket)
+			continue;
+		switch (line[0]) {
+		case '-':
+			append_lost(lost_bucket, n, line+1);
+			break;
+		case '+':
+			sline[lno-1].flag &= pmask;
+			lno++;
+			break;
+		}
+	}
+	fclose(in);
+	unlink(parent_tmp);
+}
+
+static unsigned long context = 3;
+static char combine_marker = '@';
+
+static int interesting(struct sline *sline, unsigned long all_mask)
+{
+	return ((sline->flag & all_mask) != all_mask || sline->lost_head);
+}
+
+static unsigned long line_common_diff(struct sline *sline, unsigned long all_mask)
+{
+	/*
+	 * Look at the line and see from which parents we have the
+	 * same difference.
+	 */
+
+	/* Lower bits of sline->flag records if the parent had this
+	 * line, so XOR with all_mask gives us on-bits for parents we
+	 * have differences with.
+	 */
+	unsigned long common_adds = (sline->flag ^ all_mask) & all_mask;
+	unsigned long common_removes = all_mask;
+
+	/* If all the parents have this line, that also counts as
+	 * having the same difference.
+	 */
+	if (!common_adds)
+		common_adds = all_mask;
+
+	if (sline->lost_head) {
+		/* Lost head list records the lines removed from
+		 * the parents, and parent_map records from which
+		 * parent the line was removed.
+		 */
+		struct lline *ll;
+		for (ll = sline->lost_head; ll; ll = ll->next) {
+			common_removes &= ll->parent_map;
+		}
+	}
+	return common_adds & common_removes;
+}
+
+static unsigned long line_all_diff(struct sline *sline, unsigned long all_mask)
+{
+	/*
+	 * Look at the line and see from which parents we have some difference.
+	 */
+	unsigned long different = (sline->flag ^ all_mask) & all_mask;
+	if (sline->lost_head) {
+		/* Lost head list records the lines removed from
+		 * the parents, and parent_map records from which
+		 * parent the line was removed.
+		 */
+		struct lline *ll;
+		for (ll = sline->lost_head; ll; ll = ll->next) {
+			different |= ll->parent_map;
+		}
+	}
+	return different;
+}
+
+static unsigned long adjust_hunk_tail(struct sline *sline,
+				      unsigned long all_mask,
+				      unsigned long hunk_begin,
+				      unsigned long i)
+{
+	/* i points at the first uninteresting line.
+	 * If the last line of the hunk was interesting
+	 * only because it has some deletion, then
+	 * it is not all that interesting for the
+	 * purpose of giving trailing context lines.
+	 */
+	if ((hunk_begin + 1 <= i) &&
+	    ((sline[i-1].flag & all_mask) == all_mask))
+		i--;
+	return i;
+}
+
+static unsigned long next_interesting(struct sline *sline,
+				      unsigned long mark,
+				      unsigned long i,
+				      unsigned long cnt,
+				      int uninteresting)
+{
+	while (i < cnt)
+		if (uninteresting ?
+		    !(sline[i].flag & mark) :
+		    (sline[i].flag & mark))
+			return i;
+		else
+			i++;
+	return cnt;
+}
+
+static int give_context(struct sline *sline, unsigned long cnt, int num_parent)
+{
+	unsigned long all_mask = (1UL<<num_parent) - 1;
+	unsigned long mark = (1UL<<num_parent);
+	unsigned long i;
+
+	i = next_interesting(sline, mark, 0, cnt, 0);
+	if (cnt <= i)
+		return 0;
+
+	while (i < cnt) {
+		unsigned long j = (context < i) ? (i - context) : 0;
+		unsigned long k;
+		while (j < i)
+			sline[j++].flag |= mark;
+
+	again:
+		j = next_interesting(sline, mark, i, cnt, 1);
+		if (cnt <= j)
+			break; /* the rest are all interesting */
+
+		/* lookahead context lines */
+		k = next_interesting(sline, mark, j, cnt, 0);
+		j = adjust_hunk_tail(sline, all_mask, i, j);
+
+		if (k < j + context) {
+			/* k is interesting and [j,k) are not, but
+			 * paint them interesting because the gap is small.
+			 */
+			while (j < k)
+				sline[j++].flag |= mark;
+			i = k;
+			goto again;
+		}
+
+		/* j is the first uninteresting line and there is
+		 * no overlap beyond it within context lines.
+		 */
+		i = k;
+		k = (j + context < cnt) ? j + context : cnt;
+		while (j < k)
+			sline[j++].flag |= mark;
+	}
+	return 1;
+}
+
+static int make_hunks(struct sline *sline, unsigned long cnt,
+		       int num_parent, int dense)
+{
+	unsigned long all_mask = (1UL<<num_parent) - 1;
+	unsigned long mark = (1UL<<num_parent);
+	unsigned long i;
+	int has_interesting = 0;
+
+	for (i = 0; i < cnt; i++) {
+		if (interesting(&sline[i], all_mask))
+			sline[i].flag |= mark;
+		else
+			sline[i].flag &= ~mark;
+	}
+	if (!dense)
+		return give_context(sline, cnt, num_parent);
+
+	/* Look at each hunk, and if we have changes from only one
+	 * parent, or the changes are the same from all but one
+	 * parent, mark that uninteresting.
+	 */
+	i = 0;
+	while (i < cnt) {
+		unsigned long j, hunk_begin, hunk_end;
+		int same, diff;
+		unsigned long same_diff, all_diff;
+		while (i < cnt && !(sline[i].flag & mark))
+			i++;
+		if (cnt <= i)
+			break; /* No more interesting hunks */
+		hunk_begin = i;
+		for (j = i + 1; j < cnt; j++) {
+			if (!(sline[j].flag & mark)) {
+				/* Look beyond the end to see if there
+				 * is an interesting line after this
+				 * hunk within context span.
+				 */
+				unsigned long la; /* lookahead */
+				int contin = 0;
+				la = adjust_hunk_tail(sline, all_mask,
+						     hunk_begin, j);
+				la = (la + context < cnt) ?
+					(la + context) : cnt;
+				while (j <= --la) {
+					if (sline[la].flag & mark) {
+						contin = 1;
+						break;
+					}
+				}
+				if (!contin)
+					break;
+				j = la;
+			}
+		}
+		hunk_end = j;
+
+		/* [i..hunk_end) are interesting.  Now does it have
+		 * the same change with all but one parent?
+		 */
+		same_diff = all_mask;
+		all_diff = 0;
+		for (j = i; j < hunk_end; j++) {
+			same_diff &= line_common_diff(sline + j, all_mask);
+			all_diff |= line_all_diff(sline + j, all_mask);
+		}
+		diff = same = 0;
+		for (j = 0; j < num_parent; j++) {
+			if (same_diff & (1UL<<j))
+				same++;
+			if (all_diff & (1UL<<j))
+				diff++;
+		}
+		if ((num_parent - 1 <= same) || (diff == 1)) {
+			/* This hunk is not that interesting after all */
+			for (j = hunk_begin; j < hunk_end; j++)
+				sline[j].flag &= ~mark;
+		}
+		i = hunk_end;
+	}
+
+	has_interesting = give_context(sline, cnt, num_parent);
+	return has_interesting;
+}
+
+static void dump_sline(struct sline *sline, int cnt, int num_parent)
+{
+	unsigned long mark = (1UL<<num_parent);
+	int i;
+	int lno = 0;
+
+	while (1) {
+		struct sline *sl = &sline[lno];
+		int hunk_end;
+		while (lno < cnt && !(sline[lno].flag & mark))
+			lno++;
+		if (cnt <= lno)
+			break;
+		for (hunk_end = lno + 1; hunk_end < cnt; hunk_end++)
+			if (!(sline[hunk_end].flag & mark))
+				break;
+		for (i = 0; i <= num_parent; i++) putchar(combine_marker);
+		printf(" +%d,%d ", lno+1, hunk_end-lno);
+		for (i = 0; i <= num_parent; i++) putchar(combine_marker);
+		putchar('\n');
+		while (lno < hunk_end) {
+			struct lline *ll;
+			int j;
+			sl = &sline[lno++];
+			ll = sl->lost_head;
+			while (ll) {
+				for (j = 0; j < num_parent; j++) {
+					if (ll->parent_map & (1UL<<j))
+						putchar('-');
+					else
+						putchar(' ');
+				}
+				puts(ll->line);
+				ll = ll->next;
+			}
+			for (j = 0; j < num_parent; j++) {
+				if ((1UL<<j) & sl->flag)
+					putchar(' ');
+				else
+					putchar('+');
+			}
+			printf("%.*s\n", sl->len, sl->bol);
+		}
+	}
+}
+
+int show_combined_diff(struct combine_diff_path *elem, int num_parent,
+		       int dense, const char *header, int show_empty)
+{
+	unsigned long size, cnt, lno;
+	char *result, *cp, *ep;
+	struct sline *sline; /* survived lines */
+	int i, show_hunks, shown_header = 0;
+	char ourtmp_buf[TMPPATHLEN];
+	char *ourtmp = ourtmp_buf;
+
+	/* Read the result of merge first */
+	if (memcmp(elem->sha1, null_sha1, 20)) {
+		result = grab_blob(elem->sha1, &size);
+		write_to_temp_file(ourtmp, result, size);
+	}
+	else {
+		struct stat st;
+		int fd;
+		ourtmp = elem->path;
+		if (0 <= (fd = open(ourtmp, O_RDONLY)) &&
+		    !fstat(fd, &st)) {
+			int len = st.st_size;
+			int cnt = 0;
+
+			size = len;
+			result = xmalloc(len + 1);
+			while (cnt < len) {
+				int done = xread(fd, result+cnt, len-cnt);
+				if (done == 0)
+					break;
+				if (done < 0)
+					die("read error '%s'", ourtmp);
+				cnt += done;
+			}
+			result[len] = 0;
+		}
+		else {
+			/* deleted file */
+			size = 0;
+			result = xmalloc(1);
+			result[0] = 0;
+			ourtmp = "/dev/null";
+		}
+		if (0 <= fd)
+			close(fd);
+	}
+
+	for (cnt = 0, cp = result; cp - result < size; cp++) {
+		if (*cp == '\n')
+			cnt++;
+	}
+	if (result[size-1] != '\n')
+		cnt++; /* incomplete line */
+
+	sline = xcalloc(cnt, sizeof(*sline));
+	ep = result;
+	sline[0].bol = result;
+	for (lno = 0, cp = result; cp - result < size; cp++) {
+		if (*cp == '\n') {
+			sline[lno].lost_tail = &sline[lno].lost_head;
+			sline[lno].len = cp - sline[lno].bol;
+			sline[lno].flag = (1UL<<num_parent) - 1;
+			lno++;
+			if (lno < cnt)
+				sline[lno].bol = cp + 1;
+		}
+	}
+	if (result[size-1] != '\n') {
+		sline[cnt-1].lost_tail = &sline[cnt-1].lost_head;
+		sline[cnt-1].len = size - (sline[cnt-1].bol - result);
+		sline[cnt-1].flag = (1UL<<num_parent) - 1;
+	}
+
+	for (i = 0; i < num_parent; i++)
+		combine_diff(elem->parent_sha1[i], ourtmp, sline, cnt, i);
+
+	show_hunks = make_hunks(sline, cnt, num_parent, dense);
+
+	if (header && (show_hunks || show_empty)) {
+		shown_header++;
+		puts(header);
+	}
+	if (show_hunks) {
+		printf("diff --%s ", dense ? "cc" : "combined");
+		if (quote_c_style(elem->path, NULL, NULL, 0))
+			quote_c_style(elem->path, NULL, stdout, 0);
+		else
+			printf("%s", elem->path);
+		putchar('\n');
+		dump_sline(sline, cnt, num_parent);
+	}
+	if (ourtmp == ourtmp_buf)
+		unlink(ourtmp);
+	free(result);
+
+	for (i = 0; i < cnt; i++) {
+		if (sline[i].lost_head) {
+			struct lline *ll = sline[i].lost_head;
+			while (ll) {
+				struct lline *tmp = ll;
+				ll = ll->next;
+				free(tmp);
+			}
+		}
+	}
+	free(sline);
+	return shown_header;
+}
+
+int diff_tree_combined_merge(const unsigned char *sha1,
+			     const char *header,
+			     int show_empty_merge, int dense)
+{
+	struct commit *commit = lookup_commit(sha1);
+	struct diff_options diffopts;
+	struct commit_list *parents;
+	struct combine_diff_path *p, *paths = NULL;
+	int num_parent, i, num_paths;
+
+	diff_setup(&diffopts);
+	diffopts.output_format = DIFF_FORMAT_NO_OUTPUT;
+	diffopts.recursive = 1;
+
+	/* count parents */
+	for (parents = commit->parents, num_parent = 0;
+	     parents;
+	     parents = parents->next, num_parent++)
+		; /* nothing */
+
+	/* find set of paths that everybody touches */
+	for (parents = commit->parents, i = 0;
+	     parents;
+	     parents = parents->next, i++) {
+		struct commit *parent = parents->item;
+		diff_tree_sha1(parent->object.sha1, commit->object.sha1, "",
+			       &diffopts);
+		paths = intersect_paths(paths, i, num_parent);
+		diff_flush(&diffopts);
+	}
+
+	/* find out surviving paths */
+	for (num_paths = 0, p = paths; p; p = p->next) {
+		if (p->len)
+			num_paths++;
+	}
+	if (num_paths || show_empty_merge) {
+		for (p = paths; p; p = p->next) {
+			if (!p->len)
+				continue;
+			if (show_combined_diff(p, num_parent, dense, header,
+					       show_empty_merge))
+				header = NULL;
+		}
+	}
+
+	/* Clean things up */
+	while (paths) {
+		struct combine_diff_path *tmp = paths;
+		paths = paths->next;
+		free(tmp);
+	}
+	return 0;
+}

commit.c

@@ -426,33 +426,37 @@ static int is_empty_line(const char *line, int len)
 	return !len;
 }
 
-static int add_parent_info(enum cmit_fmt fmt, char *buf, const char *line, int parents)
+static int add_merge_info(enum cmit_fmt fmt, char *buf, const struct commit *commit, int abbrev)
 {
-	int offset = 0;
+	struct commit_list *parent = commit->parents;
+	int offset;
 
-	if (fmt == CMIT_FMT_ONELINE)
-		return offset;
-	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);
+	if ((fmt == CMIT_FMT_ONELINE) || !parent || !parent->next)
+		return 0;
+
+	offset = sprintf(buf, "Merge:");
+
+	while (parent) {
+		struct commit *p = parent->item;
+		parent = parent->next;
+
+		offset += sprintf(buf + offset,
+				  abbrev ? " %s..." : " %s",
+				  abbrev
+				  ? find_unique_abbrev(p->object.sha1, abbrev)
+				  : sha1_to_hex(p->object.sha1));
 	}
+	buf[offset++] = '\n';
 	return offset;
 }
 
-unsigned long pretty_print_commit(enum cmit_fmt fmt, const char *msg, unsigned long len, char *buf, unsigned long space)
+unsigned long pretty_print_commit(enum cmit_fmt fmt, const struct commit *commit, unsigned long len, char *buf, unsigned long space, int abbrev)
 {
 	int hdr = 1, body = 0;
 	unsigned long offset = 0;
-	int parents = 0;
 	int indent = (fmt == CMIT_FMT_ONELINE) ? 0 : 4;
+	int parents_shown = 0;
+	const char *msg = commit->buffer;
 
 	for (;;) {
 		const char *line = msg;
@@ -488,9 +492,15 @@ unsigned long pretty_print_commit(enum cmit_fmt fmt, const char *msg, unsigned l
 			if (!memcmp(line, "parent ", 7)) {
 				if (linelen != 48)
 					die("bad parent line in commit");
-				offset += add_parent_info(fmt, buf + offset, line, ++parents);
+				continue;
 			}
 
+			if (!parents_shown) {
+				offset += add_merge_info(fmt, buf + offset,
+							 commit, abbrev);
+				parents_shown = 1;
+				continue;
+			}
 			/*
 			 * MEDIUM == DEFAULT shows only author with dates.
 			 * FULL shows both authors but not dates.

commit.h

@@ -48,7 +48,7 @@ enum cmit_fmt {
 };
 
 extern enum cmit_fmt get_commit_format(const char *arg);
-extern unsigned long pretty_print_commit(enum cmit_fmt fmt, const char *msg, unsigned long len, char *buf, unsigned long space);
+extern unsigned long pretty_print_commit(enum cmit_fmt fmt, const struct commit *, unsigned long len, char *buf, unsigned long space, int abbrev);
 
 /** Removes the first commit from a list sorted by date, and adds all
  * of its parents.

describe.c

@@ -11,7 +11,6 @@ static const char describe_usage[] =
 static int all = 0;	/* Default to annotated tags only */
 static int tags = 0;	/* But allow any tags if --tags is specified */
 
-#define DEFAULT_ABBREV 8 /* maybe too many */
 static int abbrev = DEFAULT_ABBREV;
 
 static int names = 0, allocs = 0;
@@ -155,7 +154,7 @@ int main(int argc, char **argv)
 			tags = 1;
 		else if (!strncmp(arg, "--abbrev=", 9)) {
 			abbrev = strtoul(arg + 9, NULL, 10);
-			if (abbrev < 4 || 40 <= abbrev)
+			if (abbrev < MINIMUM_ABBREV || 40 <= abbrev)
 				abbrev = DEFAULT_ABBREV;
 		}
 		else

diff-files.c

@@ -7,12 +7,14 @@
 #include "diff.h"
 
 static const char diff_files_usage[] =
-"git-diff-files [-q] [-0/-1/2/3] [<common diff options>] [<path>...]"
+"git-diff-files [-q] [-0/-1/2/3 |-c|--cc] [<common diff options>] [<path>...]"
 COMMON_DIFF_OPTIONS_HELP;
 
 static struct diff_options diff_options;
 static int silent = 0;
 static int diff_unmerged_stage = 2;
+static int combine_merges = 0;
+static int dense_combined_merges = 0;
 
 static void show_unmerge(const char *path)
 {
@@ -66,6 +68,10 @@ int main(int argc, const char **argv)
 			; /* no-op */
 		else if (!strcmp(argv[1], "-s"))
 			; /* no-op */
+		else if (!strcmp(argv[1], "-c"))
+			combine_merges = 1;
+		else if (!strcmp(argv[1], "--cc"))
+			dense_combined_merges = combine_merges = 1;
 		else {
 			int diff_opt_cnt;
 			diff_opt_cnt = diff_opt_parse(&diff_options,
@@ -82,6 +88,9 @@ int main(int argc, const char **argv)
 		}
 		argv++; argc--;
 	}
+	if (combine_merges) {
+		diff_options.output_format = DIFF_FORMAT_PATCH;
+	}
 
 	/* Find the directory, and set up the pathspec */
 	pathspec = get_pathspec(prefix, argv + 1);
@@ -108,14 +117,35 @@ int main(int argc, const char **argv)
 			continue;
 
 		if (ce_stage(ce)) {
-			show_unmerge(ce->name);
+			struct {
+				struct combine_diff_path p;
+				unsigned char fill[4][20];
+			} combine;
+
+			combine.p.next = NULL;
+			combine.p.len = ce_namelen(ce);
+			combine.p.path = xmalloc(combine.p.len + 1);
+			memcpy(combine.p.path, ce->name, combine.p.len);
+			combine.p.path[combine.p.len] = 0;
+			memset(combine.p.sha1, 0, 100);
+
 			while (i < entries) {
 				struct cache_entry *nce = active_cache[i];
+				int stage;
 
 				if (strcmp(ce->name, nce->name))
 					break;
+
+				/* Stage #2 (ours) is the first parent,
+				 * stage #3 (theirs) is the second.
+				 */
+				stage = ce_stage(nce);
+				if (2 <= stage)
+					memcpy(combine.p.parent_sha1[stage-2],
+					       nce->sha1, 20);
+
 				/* diff against the proper unmerged stage */
-				if (ce_stage(nce) == diff_unmerged_stage)
+				if (stage == diff_unmerged_stage)
 					ce = nce;
 				i++;
 			}
@@ -123,10 +153,19 @@ int main(int argc, const char **argv)
 			 * Compensate for loop update
 			 */
 			i--;
+
+			if (combine_merges) {
+				show_combined_diff(&combine.p, 2,
+						   dense_combined_merges,
+						   NULL, 0);
+				continue;
+			}
+
 			/*
 			 * Show the diff for the 'ce' if we found the one
 			 * from the desired stage.
 			 */
+			show_unmerge(ce->name);
 			if (ce_stage(ce) != diff_unmerged_stage)
 				continue;
 		}

diff-tree.c

@@ -6,6 +6,9 @@ static int show_root_diff = 0;
 static int no_commit_id = 0;
 static int verbose_header = 0;
 static int ignore_merges = 1;
+static int show_empty_combined = 0;
+static int combine_merges = 0;
+static int dense_combined_merges = 0;
 static int read_stdin = 0;
 
 static const char *header = NULL;
@@ -64,12 +67,13 @@ static int diff_root_tree(const unsigned char *new, const char *base)
 
 static const char *generate_header(const unsigned char *commit_sha1,
 				   const unsigned char *parent_sha1,
-				   const char *msg)
+				   const struct commit *commit)
 {
 	static char this_header[16384];
 	int offset;
 	unsigned long len;
 	int abbrev = diff_options.abbrev;
+	const char *msg = commit->buffer;
 
 	if (!verbose_header)
 		return sha1_to_hex(commit_sha1);
@@ -79,12 +83,16 @@ static const char *generate_header(const unsigned char *commit_sha1,
 	offset = sprintf(this_header, "%s%s ",
 			 header_prefix,
 			 diff_unique_abbrev(commit_sha1, abbrev));
-	offset += sprintf(this_header + offset, "(from %s)\n",
-			 parent_sha1 ?
-			 diff_unique_abbrev(parent_sha1, abbrev) : "root");
-	offset += pretty_print_commit(commit_format, msg, len,
+	if (commit_sha1 != parent_sha1)
+		offset += sprintf(this_header + offset, "(from %s)\n",
+				  parent_sha1
+				  ? diff_unique_abbrev(parent_sha1, abbrev)
+				  : "root");
+	else
+		offset += sprintf(this_header + offset, "(from parents)\n");
+	offset += pretty_print_commit(commit_format, commit, len,
 				      this_header + offset,
-				      sizeof(this_header) - offset);
+				      sizeof(this_header) - offset, abbrev);
 	return this_header;
 }
 
@@ -103,19 +111,25 @@ static int diff_tree_commit(const unsigned char *commit_sha1)
 	
 	/* Root commit? */
 	if (show_root_diff && !commit->parents) {
-		header = generate_header(sha1, NULL, commit->buffer);
+		header = generate_header(sha1, NULL, commit);
 		diff_root_tree(commit_sha1, "");
 	}
 
 	/* More than one parent? */
-	if (ignore_merges && commit->parents && commit->parents->next)
-		return 0;
+	if (commit->parents && commit->parents->next) {
+		if (ignore_merges)
+			return 0;
+		else if (combine_merges) {
+			header = generate_header(sha1, sha1, commit);
+			return diff_tree_combined_merge(sha1, header,
+							show_empty_combined,
+							dense_combined_merges);
+		}
+	}
 
 	for (parents = commit->parents; parents; parents = parents->next) {
 		struct commit *parent = parents->item;
-		header = generate_header(sha1,
-					 parent->object.sha1,
-					 commit->buffer);
+		header = generate_header(sha1, parent->object.sha1, commit);
 		diff_tree_sha1_top(parent->object.sha1, commit_sha1, "");
 		if (!header && verbose_header) {
 			header_prefix = "\ndiff-tree ";
@@ -154,7 +168,7 @@ static int diff_tree_stdin(char *line)
 }
 
 static const char diff_tree_usage[] =
-"git-diff-tree [--stdin] [-m] [-s] [-v] [--pretty] [-t] [-r] [--root] "
+"git-diff-tree [--stdin] [-m] [-c] [--cc] [-s] [-v] [--pretty] [-t] [-r] [--root] "
 "[<common diff options>] <tree-ish> [<tree-ish>] [<path>...]\n"
 "  -r            diff recursively\n"
 "  --root        include the initial commit as diff against /dev/null\n"
@@ -217,6 +231,14 @@ int main(int argc, const char **argv)
 			ignore_merges = 0;
 			continue;
 		}
+		if (!strcmp(arg, "-c")) {
+			combine_merges = 1;
+			continue;
+		}
+		if (!strcmp(arg, "--cc")) {
+			dense_combined_merges = combine_merges = 1;
+			continue;
+		}
 		if (!strcmp(arg, "-v")) {
 			verbose_header = 1;
 			header_prefix = "diff-tree ";
@@ -245,6 +267,12 @@ int main(int argc, const char **argv)
 	if (diff_options.output_format == DIFF_FORMAT_PATCH)
 		diff_options.recursive = 1;
 
+	if (combine_merges) {
+		diff_options.output_format = DIFF_FORMAT_PATCH;
+		show_empty_combined = !ignore_merges;
+		ignore_merges = 0;
+	}
+
 	diff_tree_setup_paths(get_pathspec(prefix, argv));
 	diff_setup_done(&diff_options);
 

diff.c

@@ -723,7 +723,7 @@ static void run_diff(struct diff_filepair *p, struct diff_options *o)
 
 	if (memcmp(one->sha1, two->sha1, 20)) {
 		char one_sha1[41];
-		int abbrev = o->full_index ? 40 : DIFF_DEFAULT_INDEX_ABBREV;
+		int abbrev = o->full_index ? 40 : DEFAULT_ABBREV;
 		memcpy(one_sha1, sha1_to_hex(one->sha1), 41);
 
 		len += snprintf(msg + len, sizeof(msg) - len,
@@ -846,9 +846,14 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 	else if (!strcmp(arg, "--find-copies-harder"))
 		options->find_copies_harder = 1;
 	else if (!strcmp(arg, "--abbrev"))
-		options->abbrev = DIFF_DEFAULT_ABBREV;
-	else if (!strncmp(arg, "--abbrev=", 9))
+		options->abbrev = DEFAULT_ABBREV;
+	else if (!strncmp(arg, "--abbrev=", 9)) {
 		options->abbrev = strtoul(arg + 9, NULL, 10);
+		if (options->abbrev < MINIMUM_ABBREV)
+			options->abbrev = MINIMUM_ABBREV;
+		else if (40 < options->abbrev)
+			options->abbrev = 40;
+	}
 	else
 		return 0;
 	return 1;

diff.h

@@ -56,6 +56,19 @@ extern int diff_tree(struct tree_desc *t1, struct tree_desc *t2,
 extern int diff_tree_sha1(const unsigned char *old, const unsigned char *new,
 			  const char *base, struct diff_options *opt);
 
+struct combine_diff_path {
+	struct combine_diff_path *next;
+	int len;
+	char *path;
+	unsigned char sha1[20];
+	unsigned char parent_sha1[FLEX_ARRAY][20];
+};
+
+int show_combined_diff(struct combine_diff_path *elem, int num_parent,
+		       int dense, const char *header, int show_empty);
+
+extern int diff_tree_combined_merge(const unsigned char *sha1, const char *, int, int);
+
 extern void diff_addremove(struct diff_options *,
 			   int addremove,
 			   unsigned mode,
@@ -88,9 +101,6 @@ extern int diff_setup_done(struct diff_options *);
 
 #define DIFF_PICKAXE_ALL	1
 
-#define DIFF_DEFAULT_INDEX_ABBREV	7 /* hex digits */
-#define DIFF_DEFAULT_ABBREV	7 /* hex digits */
-
 extern void diffcore_std(struct diff_options *);
 
 extern void diffcore_std_no_resolve(struct diff_options *);

rev-list.c

@@ -21,6 +21,7 @@ static const char rev_list_usage[] =
 "    --min-age=epoch\n"
 "    --sparse\n"
 "    --no-merges\n"
+"    --remove-empty\n"
 "    --all\n"
 "  ordering output:\n"
 "    --merge-order [ --show-breaks ]\n"
@@ -54,6 +55,7 @@ static int stop_traversal = 0;
 static int topo_order = 0;
 static int no_merges = 0;
 static const char **paths = NULL;
+static int remove_empty_trees = 0;
 
 static void show_commit(struct commit *commit)
 {
@@ -81,7 +83,7 @@ static void show_commit(struct commit *commit)
 
 	if (verbose_header) {
 		static char pretty_header[16384];
-		pretty_print_commit(commit_format, commit->buffer, ~0, pretty_header, sizeof(pretty_header));
+		pretty_print_commit(commit_format, commit, ~0, pretty_header, sizeof(pretty_header), 0);
 		printf("%s%c", pretty_header, hdr_termination);
 	}
 	fflush(stdout);
@@ -424,14 +426,33 @@ static void mark_edges_uninteresting(struct commit_list *list)
 	}
 }
 
-static int is_different = 0;
+#define TREE_SAME	0
+#define TREE_NEW	1
+#define TREE_DIFFERENT	2
+static int tree_difference = TREE_SAME;
 
 static void file_add_remove(struct diff_options *options,
 		    int addremove, unsigned mode,
 		    const unsigned char *sha1,
 		    const char *base, const char *path)
 {
-	is_different = 1;
+	int diff = TREE_DIFFERENT;
+
+	/*
+	 * Is it an add of a new file? It means that
+	 * the old tree didn't have it at all, so we
+	 * will turn "TREE_SAME" -> "TREE_NEW", but
+	 * leave any "TREE_DIFFERENT" alone (and if
+	 * it already was "TREE_NEW", we'll keep it
+	 * "TREE_NEW" of course).
+	 */
+	if (addremove == '+') {
+		diff = tree_difference;
+		if (diff != TREE_SAME)
+			return;
+		diff = TREE_NEW;
+	}
+	tree_difference = diff;
 }
 
 static void file_change(struct diff_options *options,
@@ -440,7 +461,7 @@ static void file_change(struct diff_options *options,
 		 const unsigned char *new_sha1,
 		 const char *base, const char *path)
 {
-	is_different = 1;
+	tree_difference = TREE_DIFFERENT;
 }
 
 static struct diff_options diff_opt = {
@@ -449,12 +470,16 @@ static struct diff_options diff_opt = {
 	.change = file_change,
 };
 
-static int same_tree(struct tree *t1, struct tree *t2)
+static int compare_tree(struct tree *t1, struct tree *t2)
 {
-	is_different = 0;
+	if (!t1)
+		return TREE_NEW;
+	if (!t2)
+		return TREE_DIFFERENT;
+	tree_difference = TREE_SAME;
 	if (diff_tree_sha1(t1->object.sha1, t2->object.sha1, "", &diff_opt) < 0)
-		return 0;
-	return !is_different;
+		return TREE_DIFFERENT;
+	return tree_difference;
 }
 
 static int same_tree_as_empty(struct tree *t1)
@@ -474,28 +499,55 @@ static int same_tree_as_empty(struct tree *t1)
 	empty.buf = "";
 	empty.size = 0;
 
-	is_different = 0;
+	tree_difference = 0;
 	retval = diff_tree(&empty, &real, "", &diff_opt);
 	free(tree);
 
-	return retval >= 0 && !is_different;
+	return retval >= 0 && !tree_difference;
 }
 
-static struct commit *try_to_simplify_merge(struct commit *commit, struct commit_list *parent)
+static void try_to_simplify_commit(struct commit *commit)
 {
+	struct commit_list **pp, *parent;
+
 	if (!commit->tree)
-		return NULL;
+		return;
 
-	while (parent) {
+	if (!commit->parents) {
+		if (!same_tree_as_empty(commit->tree))
+			commit->object.flags |= TREECHANGE;
+		return;
+	}
+
+	pp = &commit->parents;
+	while ((parent = *pp) != NULL) {
 		struct commit *p = parent->item;
-		parent = parent->next;
+
+		if (p->object.flags & UNINTERESTING) {
+			pp = &parent->next;
+			continue;
+		}
+
 		parse_commit(p);
-		if (!p->tree)
+		switch (compare_tree(p->tree, commit->tree)) {
+		case TREE_SAME:
+			parent->next = NULL;
+			commit->parents = parent;
+			return;
+
+		case TREE_NEW:
+			if (remove_empty_trees && same_tree_as_empty(p->tree)) {
+				*pp = parent->next;
+				continue;
+			}
+		/* fallthrough */
+		case TREE_DIFFERENT:
+			pp = &parent->next;
 			continue;
-		if (same_tree(commit->tree, p->tree))
-			return p;
+		}
+		die("bad tree compare for commit %s", sha1_to_hex(commit->object.sha1));
 	}
-	return NULL;
+	commit->object.flags |= TREECHANGE;
 }
 
 static void add_parents_to_list(struct commit *commit, struct commit_list **list)
@@ -531,20 +583,14 @@ static void add_parents_to_list(struct commit *commit, struct commit_list **list
 	}
 
 	/*
-	 * Ok, the commit wasn't uninteresting. If it
-	 * is a merge, try to find the parent that has
-	 * no differences in the path set if one exists.
+	 * Ok, the commit wasn't uninteresting. Try to
+	 * simplify the commit history and find the parent
+	 * that has no differences in the path set if one exists.
 	 */
-	if (paths && parent && parent->next) {
-		struct commit *preferred;
-
-		preferred = try_to_simplify_merge(commit, parent);
-		if (preferred) {
-			parent->item = preferred;
-			parent->next = NULL;
-		}
-	}
+	if (paths)
+		try_to_simplify_commit(commit);
 
+	parent = commit->parents;
 	while (parent) {
 		struct commit *p = parent->item;
 
@@ -558,33 +604,6 @@ static void add_parents_to_list(struct commit *commit, struct commit_list **list
 	}
 }
 
-static void compress_list(struct commit_list *list)
-{
-	while (list) {
-		struct commit *commit = list->item;
-		struct commit_list *parent = commit->parents;
-		list = list->next;
-
-		if (!parent) {
-			if (!same_tree_as_empty(commit->tree))
-				commit->object.flags |= TREECHANGE;
-			continue;
-		}
-
-		/*
-		 * Exactly one parent? Check if it leaves the tree
-		 * unchanged
-		 */
-		if (!parent->next) {
-			struct tree *t1 = commit->tree;
-			struct tree *t2 = parent->item->tree;
-			if (!t1 || !t2 || same_tree(t1, t2))
-				continue;
-		}
-		commit->object.flags |= TREECHANGE;
-	}
-}
-
 static struct commit_list *limit_list(struct commit_list *list)
 {
 	struct commit_list *newlist = NULL;
@@ -614,8 +633,6 @@ static struct commit_list *limit_list(struct commit_list *list)
 	}
 	if (tree_objects)
 		mark_edges_uninteresting(newlist);
-	if (paths && dense)
-		compress_list(newlist);
 	if (bisect_list)
 		newlist = find_bisection(newlist);
 	return newlist;
@@ -808,6 +825,10 @@ int main(int argc, const char **argv)
 			dense = 0;
 			continue;
 		}
+		if (!strcmp(arg, "--remove-empty")) {
+			remove_empty_trees = 1;
+			continue;
+		}
 		if (!strcmp(arg, "--")) {
 			i++;
 			break;

rev-parse.c

@@ -20,6 +20,7 @@ static char *def = NULL;
 #define REVERSED 1
 static int show_type = NORMAL;
 static int symbolic = 0;
+static int abbrev = 0;
 static int output_sq = 0;
 
 static int revs_count = 0;
@@ -95,6 +96,8 @@ static void show_rev(int type, const unsigned char *sha1, const char *name)
 		putchar('^');
 	if (symbolic && name)
 		show(name);
+	else if (abbrev)
+		show(find_unique_abbrev(sha1, abbrev));
 	else
 		show(sha1_to_hex(sha1));
 }
@@ -196,6 +199,19 @@ int main(int argc, char **argv)
 				verify = 1;
 				continue;
 			}
+			if (!strcmp(arg, "--short") ||
+			    !strncmp(arg, "--short=", 9)) {
+				filter &= ~(DO_FLAGS|DO_NOREV);
+				verify = 1;
+				abbrev = DEFAULT_ABBREV;
+				if (arg[8] == '=')
+					abbrev = strtoul(arg + 9, NULL, 10);
+				if (abbrev < MINIMUM_ABBREV)
+					abbrev = MINIMUM_ABBREV;
+				else if (40 <= abbrev)
+					abbrev = 40;
+				continue;
+			}
 			if (!strcmp(arg, "--sq")) {
 				output_sq = 1;
 				continue;
@@ -294,7 +310,9 @@ int main(int argc, char **argv)
 		}
 		if (verify)
 			die("Needed a single revision");
-		if (lstat(arg, &st) < 0)
+		if ((filter & DO_REVS) &&
+		    (filter & DO_NONFLAGS) && /* !def && */
+		    lstat(arg, &st) < 0)
 			die("'%s': %s", arg, strerror(errno));
 		as_is = 1;
 		show_file(arg);

sha1_name.c

@@ -155,7 +155,7 @@ static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 	char canonical[40];
 	unsigned char res[20];
 
-	if (len < 4)
+	if (len < MINIMUM_ABBREV)
 		return -1;
 	memset(res, 0, 20);
 	memset(canonical, 'x', 40);

show-branch.c

@@ -258,8 +258,8 @@ static void show_one_commit(struct commit *commit, int no_name)
 	char pretty[256], *cp;
 	struct commit_name *name = commit->object.util;
 	if (commit->object.parsed)
-		pretty_print_commit(CMIT_FMT_ONELINE, commit->buffer, ~0,
-				    pretty, sizeof(pretty));
+		pretty_print_commit(CMIT_FMT_ONELINE, commit, ~0,
+				    pretty, sizeof(pretty), 0);
 	else
 		strcpy(pretty, "(unavailable)");
 	if (!strncmp(pretty, "[PATCH] ", 8))