Squashed 'third_party/git/' content from commit cb71568594

git-subtree-dir: third_party/git
git-subtree-split: cb715685942260375e1eb8153b0768a376e4ece7

1 files changed, 1256 insertions, 0 deletions

diff --git a/line-log.c b/line-log.c
new file mode 100644
index 000000000000..3aff1849e7d5
--- /dev/null
+++ b/line-log.c
@@ -0,0 +1,1256 @@
+#include "git-compat-util.h"
+#include "line-range.h"
+#include "cache.h"
+#include "tag.h"
+#include "blob.h"
+#include "tree.h"
+#include "diff.h"
+#include "commit.h"
+#include "decorate.h"
+#include "revision.h"
+#include "xdiff-interface.h"
+#include "strbuf.h"
+#include "log-tree.h"
+#include "graph.h"
+#include "userdiff.h"
+#include "line-log.h"
+#include "argv-array.h"
+
+static void range_set_grow(struct range_set *rs, size_t extra)
+{
+	ALLOC_GROW(rs->ranges, rs->nr + extra, rs->alloc);
+}
+
+/* Either initialization would be fine */
+#define RANGE_SET_INIT {0}
+
+void range_set_init(struct range_set *rs, size_t prealloc)
+{
+	rs->alloc = rs->nr = 0;
+	rs->ranges = NULL;
+	if (prealloc)
+		range_set_grow(rs, prealloc);
+}
+
+void range_set_release(struct range_set *rs)
+{
+	FREE_AND_NULL(rs->ranges);
+	rs->alloc = rs->nr = 0;
+}
+
+/* dst must be uninitialized! */
+static void range_set_copy(struct range_set *dst, struct range_set *src)
+{
+	range_set_init(dst, src->nr);
+	COPY_ARRAY(dst->ranges, src->ranges, src->nr);
+	dst->nr = src->nr;
+}
+
+static void range_set_move(struct range_set *dst, struct range_set *src)
+{
+	range_set_release(dst);
+	dst->ranges = src->ranges;
+	dst->nr = src->nr;
+	dst->alloc = src->alloc;
+	src->ranges = NULL;
+	src->alloc = src->nr = 0;
+}
+
+/* tack on a _new_ range _at the end_ */
+void range_set_append_unsafe(struct range_set *rs, long a, long b)
+{
+	assert(a <= b);
+	range_set_grow(rs, 1);
+	rs->ranges[rs->nr].start = a;
+	rs->ranges[rs->nr].end = b;
+	rs->nr++;
+}
+
+void range_set_append(struct range_set *rs, long a, long b)
+{
+	assert(rs->nr == 0 || rs->ranges[rs->nr-1].end <= a);
+	range_set_append_unsafe(rs, a, b);
+}
+
+static int range_cmp(const void *_r, const void *_s)
+{
+	const struct range *r = _r;
+	const struct range *s = _s;
+
+	/* this could be simply 'return r.start-s.start', but for the types */
+	if (r->start == s->start)
+		return 0;
+	if (r->start < s->start)
+		return -1;
+	return 1;
+}
+
+/*
+ * Check that the ranges are non-empty, sorted and non-overlapping
+ */
+static void range_set_check_invariants(struct range_set *rs)
+{
+	unsigned int i;
+
+	if (!rs)
+		return;
+
+	if (rs->nr)
+		assert(rs->ranges[0].start < rs->ranges[0].end);
+
+	for (i = 1; i < rs->nr; i++) {
+		assert(rs->ranges[i-1].end < rs->ranges[i].start);
+		assert(rs->ranges[i].start < rs->ranges[i].end);
+	}
+}
+
+/*
+ * In-place pass of sorting and merging the ranges in the range set,
+ * to establish the invariants when we get the ranges from the user
+ */
+void sort_and_merge_range_set(struct range_set *rs)
+{
+	unsigned int i;
+	unsigned int o = 0; /* output cursor */
+
+	QSORT(rs->ranges, rs->nr, range_cmp);
+
+	for (i = 0; i < rs->nr; i++) {
+		if (rs->ranges[i].start == rs->ranges[i].end)
+			continue;
+		if (o > 0 && rs->ranges[i].start <= rs->ranges[o-1].end) {
+			if (rs->ranges[o-1].end < rs->ranges[i].end)
+				rs->ranges[o-1].end = rs->ranges[i].end;
+		} else {
+			rs->ranges[o].start = rs->ranges[i].start;
+			rs->ranges[o].end = rs->ranges[i].end;
+			o++;
+		}
+	}
+	assert(o <= rs->nr);
+	rs->nr = o;
+
+	range_set_check_invariants(rs);
+}
+
+/*
+ * Union of range sets (i.e., sets of line numbers).  Used to merge
+ * them when searches meet at a common ancestor.
+ *
+ * This is also where the ranges are consolidated into canonical form:
+ * overlapping and adjacent ranges are merged, and empty ranges are
+ * removed.
+ */
+static void range_set_union(struct range_set *out,
+			     struct range_set *a, struct range_set *b)
+{
+	unsigned int i = 0, j = 0;
+	struct range *ra = a->ranges;
+	struct range *rb = b->ranges;
+	/* cannot make an alias of out->ranges: it may change during grow */
+
+	assert(out->nr == 0);
+	while (i < a->nr || j < b->nr) {
+		struct range *new_range;
+		if (i < a->nr && j < b->nr) {
+			if (ra[i].start < rb[j].start)
+				new_range = &ra[i++];
+			else if (ra[i].start > rb[j].start)
+				new_range = &rb[j++];
+			else if (ra[i].end < rb[j].end)
+				new_range = &ra[i++];
+			else
+				new_range = &rb[j++];
+		} else if (i < a->nr)      /* b exhausted */
+			new_range = &ra[i++];
+		else                       /* a exhausted */
+			new_range = &rb[j++];
+		if (new_range->start == new_range->end)
+			; /* empty range */
+		else if (!out->nr || out->ranges[out->nr-1].end < new_range->start) {
+			range_set_grow(out, 1);
+			out->ranges[out->nr].start = new_range->start;
+			out->ranges[out->nr].end = new_range->end;
+			out->nr++;
+		} else if (out->ranges[out->nr-1].end < new_range->end) {
+			out->ranges[out->nr-1].end = new_range->end;
+		}
+	}
+}
+
+/*
+ * Difference of range sets (out = a \ b).  Pass the "interesting"
+ * ranges as 'a' and the target side of the diff as 'b': it removes
+ * the ranges for which the commit is responsible.
+ */
+static void range_set_difference(struct range_set *out,
+				  struct range_set *a, struct range_set *b)
+{
+	unsigned int i, j =  0;
+	for (i = 0; i < a->nr; i++) {
+		long start = a->ranges[i].start;
+		long end = a->ranges[i].end;
+		while (start < end) {
+			while (j < b->nr && start >= b->ranges[j].end)
+				/*
+				 * a:         |-------
+				 * b: ------|
+				 */
+				j++;
+			if (j >= b->nr || end < b->ranges[j].start) {
+				/*
+				 * b exhausted, or
+				 * a:  ----|
+				 * b:         |----
+				 */
+				range_set_append(out, start, end);
+				break;
+			}
+			if (start >= b->ranges[j].start) {
+				/*
+				 * a:     |--????
+				 * b: |------|
+				 */
+				start = b->ranges[j].end;
+			} else if (end > b->ranges[j].start) {
+				/*
+				 * a: |-----|
+				 * b:    |--?????
+				 */
+				if (start < b->ranges[j].start)
+					range_set_append(out, start, b->ranges[j].start);
+				start = b->ranges[j].end;
+			}
+		}
+	}
+}
+
+static void diff_ranges_init(struct diff_ranges *diff)
+{
+	range_set_init(&diff->parent, 0);
+	range_set_init(&diff->target, 0);
+}
+
+static void diff_ranges_release(struct diff_ranges *diff)
+{
+	range_set_release(&diff->parent);
+	range_set_release(&diff->target);
+}
+
+static void line_log_data_init(struct line_log_data *r)
+{
+	memset(r, 0, sizeof(struct line_log_data));
+	range_set_init(&r->ranges, 0);
+}
+
+static void line_log_data_clear(struct line_log_data *r)
+{
+	range_set_release(&r->ranges);
+	if (r->pair)
+		diff_free_filepair(r->pair);
+}
+
+static void free_line_log_data(struct line_log_data *r)
+{
+	while (r) {
+		struct line_log_data *next = r->next;
+		line_log_data_clear(r);
+		free(r);
+		r = next;
+	}
+}
+
+static struct line_log_data *
+search_line_log_data(struct line_log_data *list, const char *path,
+		     struct line_log_data **insertion_point)
+{
+	struct line_log_data *p = list;
+	if (insertion_point)
+		*insertion_point = NULL;
+	while (p) {
+		int cmp = strcmp(p->path, path);
+		if (!cmp)
+			return p;
+		if (insertion_point && cmp < 0)
+			*insertion_point = p;
+		p = p->next;
+	}
+	return NULL;
+}
+
+/*
+ * Note: takes ownership of 'path', which happens to be what the only
+ * caller needs.
+ */
+static void line_log_data_insert(struct line_log_data **list,
+				 char *path,
+				 long begin, long end)
+{
+	struct line_log_data *ip;
+	struct line_log_data *p = search_line_log_data(*list, path, &ip);
+
+	if (p) {
+		range_set_append_unsafe(&p->ranges, begin, end);
+		free(path);
+		return;
+	}
+
+	p = xcalloc(1, sizeof(struct line_log_data));
+	p->path = path;
+	range_set_append(&p->ranges, begin, end);
+	if (ip) {
+		p->next = ip->next;
+		ip->next = p;
+	} else {
+		p->next = *list;
+		*list = p;
+	}
+}
+
+struct collect_diff_cbdata {
+	struct diff_ranges *diff;
+};
+
+static int collect_diff_cb(long start_a, long count_a,
+			   long start_b, long count_b,
+			   void *data)
+{
+	struct collect_diff_cbdata *d = data;
+
+	if (count_a >= 0)
+		range_set_append(&d->diff->parent, start_a, start_a + count_a);
+	if (count_b >= 0)
+		range_set_append(&d->diff->target, start_b, start_b + count_b);
+
+	return 0;
+}
+
+static int collect_diff(mmfile_t *parent, mmfile_t *target, struct diff_ranges *out)
+{
+	struct collect_diff_cbdata cbdata = {NULL};
+	xpparam_t xpp;
+	xdemitconf_t xecfg;
+	xdemitcb_t ecb;
+
+	memset(&xpp, 0, sizeof(xpp));
+	memset(&xecfg, 0, sizeof(xecfg));
+	xecfg.ctxlen = xecfg.interhunkctxlen = 0;
+
+	cbdata.diff = out;
+	xecfg.hunk_func = collect_diff_cb;
+	memset(&ecb, 0, sizeof(ecb));
+	ecb.priv = &cbdata;
+	return xdi_diff(parent, target, &xpp, &xecfg, &ecb);
+}
+
+/*
+ * These are handy for debugging.  Removing them with #if 0 silences
+ * the "unused function" warning.
+ */
+#if 0
+static void dump_range_set(struct range_set *rs, const char *desc)
+{
+	int i;
+	printf("range set %s (%d items):\n", desc, rs->nr);
+	for (i = 0; i < rs->nr; i++)
+		printf("\t[%ld,%ld]\n", rs->ranges[i].start, rs->ranges[i].end);
+}
+
+static void dump_line_log_data(struct line_log_data *r)
+{
+	char buf[4096];
+	while (r) {
+		snprintf(buf, 4096, "file %s\n", r->path);
+		dump_range_set(&r->ranges, buf);
+		r = r->next;
+	}
+}
+
+static void dump_diff_ranges(struct diff_ranges *diff, const char *desc)
+{
+	int i;
+	assert(diff->parent.nr == diff->target.nr);
+	printf("diff ranges %s (%d items):\n", desc, diff->parent.nr);
+	printf("\tparent\ttarget\n");
+	for (i = 0; i < diff->parent.nr; i++) {
+		printf("\t[%ld,%ld]\t[%ld,%ld]\n",
+		       diff->parent.ranges[i].start,
+		       diff->parent.ranges[i].end,
+		       diff->target.ranges[i].start,
+		       diff->target.ranges[i].end);
+	}
+}
+#endif
+
+
+static int ranges_overlap(struct range *a, struct range *b)
+{
+	return !(a->end <= b->start || b->end <= a->start);
+}
+
+/*
+ * Given a diff and the set of interesting ranges, determine all hunks
+ * of the diff which touch (overlap) at least one of the interesting
+ * ranges in the target.
+ */
+static void diff_ranges_filter_touched(struct diff_ranges *out,
+				       struct diff_ranges *diff,
+				       struct range_set *rs)
+{
+	unsigned int i, j = 0;
+
+	assert(out->target.nr == 0);
+
+	for (i = 0; i < diff->target.nr; i++) {
+		while (diff->target.ranges[i].start > rs->ranges[j].end) {
+			j++;
+			if (j == rs->nr)
+				return;
+		}
+		if (ranges_overlap(&diff->target.ranges[i], &rs->ranges[j])) {
+			range_set_append(&out->parent,
+					 diff->parent.ranges[i].start,
+					 diff->parent.ranges[i].end);
+			range_set_append(&out->target,
+					 diff->target.ranges[i].start,
+					 diff->target.ranges[i].end);
+		}
+	}
+}
+
+/*
+ * Adjust the line counts in 'rs' to account for the lines
+ * added/removed in the diff.
+ */
+static void range_set_shift_diff(struct range_set *out,
+				 struct range_set *rs,
+				 struct diff_ranges *diff)
+{
+	unsigned int i, j = 0;
+	long offset = 0;
+	struct range *src = rs->ranges;
+	struct range *target = diff->target.ranges;
+	struct range *parent = diff->parent.ranges;
+
+	for (i = 0; i < rs->nr; i++) {
+		while (j < diff->target.nr && src[i].start >= target[j].start) {
+			offset += (parent[j].end-parent[j].start)
+				- (target[j].end-target[j].start);
+			j++;
+		}
+		range_set_append(out, src[i].start+offset, src[i].end+offset);
+	}
+}
+
+/*
+ * Given a diff and the set of interesting ranges, map the ranges
+ * across the diff.  That is: observe that the target commit takes
+ * blame for all the + (target-side) ranges.  So for every pair of
+ * ranges in the diff that was touched, we remove the latter and add
+ * its parent side.
+ */
+static void range_set_map_across_diff(struct range_set *out,
+				      struct range_set *rs,
+				      struct diff_ranges *diff,
+				      struct diff_ranges **touched_out)
+{
+	struct diff_ranges *touched = xmalloc(sizeof(*touched));
+	struct range_set tmp1 = RANGE_SET_INIT;
+	struct range_set tmp2 = RANGE_SET_INIT;
+
+	diff_ranges_init(touched);
+	diff_ranges_filter_touched(touched, diff, rs);
+	range_set_difference(&tmp1, rs, &touched->target);
+	range_set_shift_diff(&tmp2, &tmp1, diff);
+	range_set_union(out, &tmp2, &touched->parent);
+	range_set_release(&tmp1);
+	range_set_release(&tmp2);
+
+	*touched_out = touched;
+}
+
+static struct commit *check_single_commit(struct rev_info *revs)
+{
+	struct object *commit = NULL;
+	int found = -1;
+	int i;
+
+	for (i = 0; i < revs->pending.nr; i++) {
+		struct object *obj = revs->pending.objects[i].item;
+		if (obj->flags & UNINTERESTING)
+			continue;
+		obj = deref_tag(revs->repo, obj, NULL, 0);
+		if (obj->type != OBJ_COMMIT)
+			die("Non commit %s?", revs->pending.objects[i].name);
+		if (commit)
+			die("More than one commit to dig from: %s and %s?",
+			    revs->pending.objects[i].name,
+			    revs->pending.objects[found].name);
+		commit = obj;
+		found = i;
+	}
+
+	if (!commit)
+		die("No commit specified?");
+
+	return (struct commit *) commit;
+}
+
+static void fill_blob_sha1(struct repository *r, struct commit *commit,
+			   struct diff_filespec *spec)
+{
+	unsigned short mode;
+	struct object_id oid;
+
+	if (get_tree_entry(r, &commit->object.oid, spec->path, &oid, &mode))
+		die("There is no path %s in the commit", spec->path);
+	fill_filespec(spec, &oid, 1, mode);
+
+	return;
+}
+
+static void fill_line_ends(struct repository *r,
+			   struct diff_filespec *spec,
+			   long *lines,
+			   unsigned long **line_ends)
+{
+	int num = 0, size = 50;
+	long cur = 0;
+	unsigned long *ends = NULL;
+	char *data = NULL;
+
+	if (diff_populate_filespec(r, spec, 0))
+		die("Cannot read blob %s", oid_to_hex(&spec->oid));
+
+	ALLOC_ARRAY(ends, size);
+	ends[cur++] = 0;
+	data = spec->data;
+	while (num < spec->size) {
+		if (data[num] == '\n' || num == spec->size - 1) {
+			ALLOC_GROW(ends, (cur + 1), size);
+			ends[cur++] = num;
+		}
+		num++;
+	}
+
+	/* shrink the array to fit the elements */
+	REALLOC_ARRAY(ends, cur);
+	*lines = cur-1;
+	*line_ends = ends;
+}
+
+struct nth_line_cb {
+	struct diff_filespec *spec;
+	long lines;
+	unsigned long *line_ends;
+};
+
+static const char *nth_line(void *data, long line)
+{
+	struct nth_line_cb *d = data;
+	assert(d && line <= d->lines);
+	assert(d->spec && d->spec->data);
+
+	if (line == 0)
+		return (char *)d->spec->data;
+	else
+		return (char *)d->spec->data + d->line_ends[line] + 1;
+}
+
+static struct line_log_data *
+parse_lines(struct repository *r, struct commit *commit,
+	    const char *prefix, struct string_list *args)
+{
+	long lines = 0;
+	unsigned long *ends = NULL;
+	struct nth_line_cb cb_data;
+	struct string_list_item *item;
+	struct line_log_data *ranges = NULL;
+	struct line_log_data *p;
+
+	for_each_string_list_item(item, args) {
+		const char *name_part, *range_part;
+		char *full_name;
+		struct diff_filespec *spec;
+		long begin = 0, end = 0;
+		long anchor;
+
+		name_part = skip_range_arg(item->string, r->index);
+		if (!name_part || *name_part != ':' || !name_part[1])
+			die("-L argument not 'start,end:file' or ':funcname:file': %s",
+			    item->string);
+		range_part = xstrndup(item->string, name_part - item->string);
+		name_part++;
+
+		full_name = prefix_path(prefix, prefix ? strlen(prefix) : 0,
+					name_part);
+
+		spec = alloc_filespec(full_name);
+		fill_blob_sha1(r, commit, spec);
+		fill_line_ends(r, spec, &lines, &ends);
+		cb_data.spec = spec;
+		cb_data.lines = lines;
+		cb_data.line_ends = ends;
+
+		p = search_line_log_data(ranges, full_name, NULL);
+		if (p && p->ranges.nr)
+			anchor = p->ranges.ranges[p->ranges.nr - 1].end + 1;
+		else
+			anchor = 1;
+
+		if (parse_range_arg(range_part, nth_line, &cb_data,
+				    lines, anchor, &begin, &end,
+				    full_name, r->index))
+			die("malformed -L argument '%s'", range_part);
+		if ((!lines && (begin || end)) || lines < begin)
+			die("file %s has only %lu lines", name_part, lines);
+		if (begin < 1)
+			begin = 1;
+		if (end < 1 || lines < end)
+			end = lines;
+		begin--;
+		line_log_data_insert(&ranges, full_name, begin, end);
+
+		free_filespec(spec);
+		FREE_AND_NULL(ends);
+	}
+
+	for (p = ranges; p; p = p->next)
+		sort_and_merge_range_set(&p->ranges);
+
+	return ranges;
+}
+
+static struct line_log_data *line_log_data_copy_one(struct line_log_data *r)
+{
+	struct line_log_data *ret = xmalloc(sizeof(*ret));
+
+	assert(r);
+	line_log_data_init(ret);
+	range_set_copy(&ret->ranges, &r->ranges);
+
+	ret->path = xstrdup(r->path);
+
+	return ret;
+}
+
+static struct line_log_data *
+line_log_data_copy(struct line_log_data *r)
+{
+	struct line_log_data *ret = NULL;
+	struct line_log_data *tmp = NULL, *prev = NULL;
+
+	assert(r);
+	ret = tmp = prev = line_log_data_copy_one(r);
+	r = r->next;
+	while (r) {
+		tmp = line_log_data_copy_one(r);
+		prev->next = tmp;
+		prev = tmp;
+		r = r->next;
+	}
+
+	return ret;
+}
+
+/* merge two range sets across files */
+static struct line_log_data *line_log_data_merge(struct line_log_data *a,
+						 struct line_log_data *b)
+{
+	struct line_log_data *head = NULL, **pp = &head;
+
+	while (a || b) {
+		struct line_log_data *src;
+		struct line_log_data *src2 = NULL;
+		struct line_log_data *d;
+		int cmp;
+		if (!a)
+			cmp = 1;
+		else if (!b)
+			cmp = -1;
+		else
+			cmp = strcmp(a->path, b->path);
+		if (cmp < 0) {
+			src = a;
+			a = a->next;
+		} else if (cmp == 0) {
+			src = a;
+			a = a->next;
+			src2 = b;
+			b = b->next;
+		} else {
+			src = b;
+			b = b->next;
+		}
+		d = xmalloc(sizeof(struct line_log_data));
+		line_log_data_init(d);
+		d->path = xstrdup(src->path);
+		*pp = d;
+		pp = &d->next;
+		if (src2)
+			range_set_union(&d->ranges, &src->ranges, &src2->ranges);
+		else
+			range_set_copy(&d->ranges, &src->ranges);
+	}
+
+	return head;
+}
+
+static void add_line_range(struct rev_info *revs, struct commit *commit,
+			   struct line_log_data *range)
+{
+	struct line_log_data *old_line = NULL;
+	struct line_log_data *new_line = NULL;
+
+	old_line = lookup_decoration(&revs->line_log_data, &commit->object);
+	if (old_line && range) {
+		new_line = line_log_data_merge(old_line, range);
+		free_line_log_data(old_line);
+	} else if (range)
+		new_line = line_log_data_copy(range);
+
+	if (new_line)
+		add_decoration(&revs->line_log_data, &commit->object, new_line);
+}
+
+static void clear_commit_line_range(struct rev_info *revs, struct commit *commit)
+{
+	struct line_log_data *r;
+	r = lookup_decoration(&revs->line_log_data, &commit->object);
+	if (!r)
+		return;
+	free_line_log_data(r);
+	add_decoration(&revs->line_log_data, &commit->object, NULL);
+}
+
+static struct line_log_data *lookup_line_range(struct rev_info *revs,
+					       struct commit *commit)
+{
+	struct line_log_data *ret = NULL;
+	struct line_log_data *d;
+
+	ret = lookup_decoration(&revs->line_log_data, &commit->object);
+
+	for (d = ret; d; d = d->next)
+		range_set_check_invariants(&d->ranges);
+
+	return ret;
+}
+
+void line_log_init(struct rev_info *rev, const char *prefix, struct string_list *args)
+{
+	struct commit *commit = NULL;
+	struct line_log_data *range;
+
+	commit = check_single_commit(rev);
+	range = parse_lines(rev->diffopt.repo, commit, prefix, args);
+	add_line_range(rev, commit, range);
+
+	if (!rev->diffopt.detect_rename) {
+		struct line_log_data *r;
+		struct argv_array array = ARGV_ARRAY_INIT;
+		const char **paths;
+
+		for (r = range; r; r = r->next)
+			argv_array_push(&array, r->path);
+		paths = argv_array_detach(&array);
+
+		parse_pathspec(&rev->diffopt.pathspec, 0,
+			       PATHSPEC_PREFER_FULL, "", paths);
+		/* strings are now owned by pathspec */
+		free(paths);
+	}
+}
+
+static void move_diff_queue(struct diff_queue_struct *dst,
+			    struct diff_queue_struct *src)
+{
+	assert(src != dst);
+	memcpy(dst, src, sizeof(struct diff_queue_struct));
+	DIFF_QUEUE_CLEAR(src);
+}
+
+static void filter_diffs_for_paths(struct line_log_data *range, int keep_deletions)
+{
+	int i;
+	struct diff_queue_struct outq;
+	DIFF_QUEUE_CLEAR(&outq);
+
+	for (i = 0; i < diff_queued_diff.nr; i++) {
+		struct diff_filepair *p = diff_queued_diff.queue[i];
+		struct line_log_data *rg = NULL;
+
+		if (!DIFF_FILE_VALID(p->two)) {
+			if (keep_deletions)
+				diff_q(&outq, p);
+			else
+				diff_free_filepair(p);
+			continue;
+		}
+		for (rg = range; rg; rg = rg->next) {
+			if (!strcmp(rg->path, p->two->path))
+				break;
+		}
+		if (rg)
+			diff_q(&outq, p);
+		else
+			diff_free_filepair(p);
+	}
+	free(diff_queued_diff.queue);
+	diff_queued_diff = outq;
+}
+
+static inline int diff_might_be_rename(void)
+{
+	int i;
+	for (i = 0; i < diff_queued_diff.nr; i++)
+		if (!DIFF_FILE_VALID(diff_queued_diff.queue[i]->one)) {
+			/* fprintf(stderr, "diff_might_be_rename found creation of: %s\n", */
+			/* 	diff_queued_diff.queue[i]->two->path); */
+			return 1;
+		}
+	return 0;
+}
+
+static void queue_diffs(struct line_log_data *range,
+			struct diff_options *opt,
+			struct diff_queue_struct *queue,
+			struct commit *commit, struct commit *parent)
+{
+	assert(commit);
+
+	DIFF_QUEUE_CLEAR(&diff_queued_diff);
+	diff_tree_oid(parent ? get_commit_tree_oid(parent) : NULL,
+		      get_commit_tree_oid(commit), "", opt);
+	if (opt->detect_rename) {
+		filter_diffs_for_paths(range, 1);
+		if (diff_might_be_rename())
+			diffcore_std(opt);
+		filter_diffs_for_paths(range, 0);
+	}
+	move_diff_queue(queue, &diff_queued_diff);
+}
+
+static char *get_nth_line(long line, unsigned long *ends, void *data)
+{
+	if (line == 0)
+		return (char *)data;
+	else
+		return (char *)data + ends[line] + 1;
+}
+
+static void print_line(const char *prefix, char first,
+		       long line, unsigned long *ends, void *data,
+		       const char *color, const char *reset, FILE *file)
+{
+	char *begin = get_nth_line(line, ends, data);
+	char *end = get_nth_line(line+1, ends, data);
+	int had_nl = 0;
+
+	if (end > begin && end[-1] == '\n') {
+		end--;
+		had_nl = 1;
+	}
+
+	fputs(prefix, file);
+	fputs(color, file);
+	putc(first, file);
+	fwrite(begin, 1, end-begin, file);
+	fputs(reset, file);
+	putc('\n', file);
+	if (!had_nl)
+		fputs("\\ No newline at end of file\n", file);
+}
+
+static char *output_prefix(struct diff_options *opt)
+{
+	char *prefix = "";
+
+	if (opt->output_prefix) {
+		struct strbuf *sb = opt->output_prefix(opt, opt->output_prefix_data);
+		prefix = sb->buf;
+	}
+
+	return prefix;
+}
+
+static void dump_diff_hacky_one(struct rev_info *rev, struct line_log_data *range)
+{
+	unsigned int i, j = 0;
+	long p_lines, t_lines;
+	unsigned long *p_ends = NULL, *t_ends = NULL;
+	struct diff_filepair *pair = range->pair;
+	struct diff_ranges *diff = &range->diff;
+
+	struct diff_options *opt = &rev->diffopt;
+	char *prefix = output_prefix(opt);
+	const char *c_reset = diff_get_color(opt->use_color, DIFF_RESET);
+	const char *c_frag = diff_get_color(opt->use_color, DIFF_FRAGINFO);
+	const char *c_meta = diff_get_color(opt->use_color, DIFF_METAINFO);
+	const char *c_old = diff_get_color(opt->use_color, DIFF_FILE_OLD);
+	const char *c_new = diff_get_color(opt->use_color, DIFF_FILE_NEW);
+	const char *c_context = diff_get_color(opt->use_color, DIFF_CONTEXT);
+
+	if (!pair || !diff)
+		return;
+
+	if (pair->one->oid_valid)
+		fill_line_ends(rev->diffopt.repo, pair->one, &p_lines, &p_ends);
+	fill_line_ends(rev->diffopt.repo, pair->two, &t_lines, &t_ends);
+
+	fprintf(opt->file, "%s%sdiff --git a/%s b/%s%s\n", prefix, c_meta, pair->one->path, pair->two->path, c_reset);
+	fprintf(opt->file, "%s%s--- %s%s%s\n", prefix, c_meta,
+	       pair->one->oid_valid ? "a/" : "",
+	       pair->one->oid_valid ? pair->one->path : "/dev/null",
+	       c_reset);
+	fprintf(opt->file, "%s%s+++ b/%s%s\n", prefix, c_meta, pair->two->path, c_reset);
+	for (i = 0; i < range->ranges.nr; i++) {
+		long p_start, p_end;
+		long t_start = range->ranges.ranges[i].start;
+		long t_end = range->ranges.ranges[i].end;
+		long t_cur = t_start;
+		unsigned int j_last;
+
+		while (j < diff->target.nr && diff->target.ranges[j].end < t_start)
+			j++;
+		if (j == diff->target.nr || diff->target.ranges[j].start > t_end)
+			continue;
+
+		/* Scan ahead to determine the last diff that falls in this range */
+		j_last = j;
+		while (j_last < diff->target.nr && diff->target.ranges[j_last].start < t_end)
+			j_last++;
+		if (j_last > j)
+			j_last--;
+
+		/*
+		 * Compute parent hunk headers: we know that the diff
+		 * has the correct line numbers (but not all hunks).
+		 * So it suffices to shift the start/end according to
+		 * the line numbers of the first/last hunk(s) that
+		 * fall in this range.
+		 */
+		if (t_start < diff->target.ranges[j].start)
+			p_start = diff->parent.ranges[j].start - (diff->target.ranges[j].start-t_start);
+		else
+			p_start = diff->parent.ranges[j].start;
+		if (t_end > diff->target.ranges[j_last].end)
+			p_end = diff->parent.ranges[j_last].end + (t_end-diff->target.ranges[j_last].end);
+		else
+			p_end = diff->parent.ranges[j_last].end;
+
+		if (!p_start && !p_end) {
+			p_start = -1;
+			p_end = -1;
+		}
+
+		/* Now output a diff hunk for this range */
+		fprintf(opt->file, "%s%s@@ -%ld,%ld +%ld,%ld @@%s\n",
+		       prefix, c_frag,
+		       p_start+1, p_end-p_start, t_start+1, t_end-t_start,
+		       c_reset);
+		while (j < diff->target.nr && diff->target.ranges[j].start < t_end) {
+			int k;
+			for (; t_cur < diff->target.ranges[j].start; t_cur++)
+				print_line(prefix, ' ', t_cur, t_ends, pair->two->data,
+					   c_context, c_reset, opt->file);
+			for (k = diff->parent.ranges[j].start; k < diff->parent.ranges[j].end; k++)
+				print_line(prefix, '-', k, p_ends, pair->one->data,
+					   c_old, c_reset, opt->file);
+			for (; t_cur < diff->target.ranges[j].end && t_cur < t_end; t_cur++)
+				print_line(prefix, '+', t_cur, t_ends, pair->two->data,
+					   c_new, c_reset, opt->file);
+			j++;
+		}
+		for (; t_cur < t_end; t_cur++)
+			print_line(prefix, ' ', t_cur, t_ends, pair->two->data,
+				   c_context, c_reset, opt->file);
+	}
+
+	free(p_ends);
+	free(t_ends);
+}
+
+/*
+ * NEEDSWORK: manually building a diff here is not the Right
+ * Thing(tm).  log -L should be built into the diff pipeline.
+ */
+static void dump_diff_hacky(struct rev_info *rev, struct line_log_data *range)
+{
+	fprintf(rev->diffopt.file, "%s\n", output_prefix(&rev->diffopt));
+	while (range) {
+		dump_diff_hacky_one(rev, range);
+		range = range->next;
+	}
+}
+
+/*
+ * Unlike most other functions, this destructively operates on
+ * 'range'.
+ */
+static int process_diff_filepair(struct rev_info *rev,
+				 struct diff_filepair *pair,
+				 struct line_log_data *range,
+				 struct diff_ranges **diff_out)
+{
+	struct line_log_data *rg = range;
+	struct range_set tmp;
+	struct diff_ranges diff;
+	mmfile_t file_parent, file_target;
+
+	assert(pair->two->path);
+	while (rg) {
+		assert(rg->path);
+		if (!strcmp(rg->path, pair->two->path))
+			break;
+		rg = rg->next;
+	}
+
+	if (!rg)
+		return 0;
+	if (rg->ranges.nr == 0)
+		return 0;
+
+	assert(pair->two->oid_valid);
+	diff_populate_filespec(rev->diffopt.repo, pair->two, 0);
+	file_target.ptr = pair->two->data;
+	file_target.size = pair->two->size;
+
+	if (pair->one->oid_valid) {
+		diff_populate_filespec(rev->diffopt.repo, pair->one, 0);
+		file_parent.ptr = pair->one->data;
+		file_parent.size = pair->one->size;
+	} else {
+		file_parent.ptr = "";
+		file_parent.size = 0;
+	}
+
+	diff_ranges_init(&diff);
+	if (collect_diff(&file_parent, &file_target, &diff))
+		die("unable to generate diff for %s", pair->one->path);
+
+	/* NEEDSWORK should apply some heuristics to prevent mismatches */
+	free(rg->path);
+	rg->path = xstrdup(pair->one->path);
+
+	range_set_init(&tmp, 0);
+	range_set_map_across_diff(&tmp, &rg->ranges, &diff, diff_out);
+	range_set_release(&rg->ranges);
+	range_set_move(&rg->ranges, &tmp);
+
+	diff_ranges_release(&diff);
+
+	return ((*diff_out)->parent.nr > 0);
+}
+
+static struct diff_filepair *diff_filepair_dup(struct diff_filepair *pair)
+{
+	struct diff_filepair *new_filepair = xmalloc(sizeof(struct diff_filepair));
+	new_filepair->one = pair->one;
+	new_filepair->two = pair->two;
+	new_filepair->one->count++;
+	new_filepair->two->count++;
+	return new_filepair;
+}
+
+static void free_diffqueues(int n, struct diff_queue_struct *dq)
+{
+	int i, j;
+	for (i = 0; i < n; i++)
+		for (j = 0; j < dq[i].nr; j++)
+			diff_free_filepair(dq[i].queue[j]);
+	free(dq);
+}
+
+static int process_all_files(struct line_log_data **range_out,
+			     struct rev_info *rev,
+			     struct diff_queue_struct *queue,
+			     struct line_log_data *range)
+{
+	int i, changed = 0;
+
+	*range_out = line_log_data_copy(range);
+
+	for (i = 0; i < queue->nr; i++) {
+		struct diff_ranges *pairdiff = NULL;
+		struct diff_filepair *pair = queue->queue[i];
+		if (process_diff_filepair(rev, pair, *range_out, &pairdiff)) {
+			/*
+			 * Store away the diff for later output.  We
+			 * tuck it in the ranges we got as _input_,
+			 * since that's the commit that caused the
+			 * diff.
+			 *
+			 * NEEDSWORK not enough when we get around to
+			 * doing something interesting with merges;
+			 * currently each invocation on a merge parent
+			 * trashes the previous one's diff.
+			 *
+			 * NEEDSWORK tramples over data structures not owned here
+			 */
+			struct line_log_data *rg = range;
+			changed++;
+			while (rg && strcmp(rg->path, pair->two->path))
+				rg = rg->next;
+			assert(rg);
+			rg->pair = diff_filepair_dup(queue->queue[i]);
+			memcpy(&rg->diff, pairdiff, sizeof(struct diff_ranges));
+		}
+		free(pairdiff);
+	}
+
+	return changed;
+}
+
+int line_log_print(struct rev_info *rev, struct commit *commit)
+{
+
+	show_log(rev);
+	if (!(rev->diffopt.output_format & DIFF_FORMAT_NO_OUTPUT)) {
+		struct line_log_data *range = lookup_line_range(rev, commit);
+		dump_diff_hacky(rev, range);
+	}
+	return 1;
+}
+
+static int process_ranges_ordinary_commit(struct rev_info *rev, struct commit *commit,
+					  struct line_log_data *range)
+{
+	struct commit *parent = NULL;
+	struct diff_queue_struct queue;
+	struct line_log_data *parent_range;
+	int changed;
+
+	if (commit->parents)
+		parent = commit->parents->item;
+
+	queue_diffs(range, &rev->diffopt, &queue, commit, parent);
+	changed = process_all_files(&parent_range, rev, &queue, range);
+	if (parent)
+		add_line_range(rev, parent, parent_range);
+	free_line_log_data(parent_range);
+	return changed;
+}
+
+static int process_ranges_merge_commit(struct rev_info *rev, struct commit *commit,
+				       struct line_log_data *range)
+{
+	struct diff_queue_struct *diffqueues;
+	struct line_log_data **cand;
+	struct commit **parents;
+	struct commit_list *p;
+	int i;
+	int nparents = commit_list_count(commit->parents);
+
+	if (nparents > 1 && rev->first_parent_only)
+		nparents = 1;
+
+	ALLOC_ARRAY(diffqueues, nparents);
+	ALLOC_ARRAY(cand, nparents);
+	ALLOC_ARRAY(parents, nparents);
+
+	p = commit->parents;
+	for (i = 0; i < nparents; i++) {
+		parents[i] = p->item;
+		p = p->next;
+		queue_diffs(range, &rev->diffopt, &diffqueues[i], commit, parents[i]);
+	}
+
+	for (i = 0; i < nparents; i++) {
+		int changed;
+		cand[i] = NULL;
+		changed = process_all_files(&cand[i], rev, &diffqueues[i], range);
+		if (!changed) {
+			/*
+			 * This parent can take all the blame, so we
+			 * don't follow any other path in history
+			 */
+			add_line_range(rev, parents[i], cand[i]);
+			clear_commit_line_range(rev, commit);
+			commit_list_append(parents[i], &commit->parents);
+			free(parents);
+			free(cand);
+			free_diffqueues(nparents, diffqueues);
+			/* NEEDSWORK leaking like a sieve */
+			return 0;
+		}
+	}
+
+	/*
+	 * No single parent took the blame.  We add the candidates
+	 * from the above loop to the parents.
+	 */
+	for (i = 0; i < nparents; i++) {
+		add_line_range(rev, parents[i], cand[i]);
+	}
+
+	clear_commit_line_range(rev, commit);
+	free(parents);
+	free(cand);
+	free_diffqueues(nparents, diffqueues);
+	return 1;
+
+	/* NEEDSWORK evil merge detection stuff */
+	/* NEEDSWORK leaking like a sieve */
+}
+
+static int process_ranges_arbitrary_commit(struct rev_info *rev, struct commit *commit)
+{
+	struct line_log_data *range = lookup_line_range(rev, commit);
+	int changed = 0;
+
+	if (range) {
+		if (!commit->parents || !commit->parents->next)
+			changed = process_ranges_ordinary_commit(rev, commit, range);
+		else
+			changed = process_ranges_merge_commit(rev, commit, range);
+	}
+
+	if (!changed)
+		commit->object.flags |= TREESAME;
+
+	return changed;
+}
+
+static enum rewrite_result line_log_rewrite_one(struct rev_info *rev, struct commit **pp)
+{
+	for (;;) {
+		struct commit *p = *pp;
+		if (p->parents && p->parents->next)
+			return rewrite_one_ok;
+		if (p->object.flags & UNINTERESTING)
+			return rewrite_one_ok;
+		if (!(p->object.flags & TREESAME))
+			return rewrite_one_ok;
+		if (!p->parents)
+			return rewrite_one_noparents;
+		*pp = p->parents->item;
+	}
+}
+
+int line_log_filter(struct rev_info *rev)
+{
+	struct commit *commit;
+	struct commit_list *list = rev->commits;
+	struct commit_list *out = NULL, **pp = &out;
+
+	while (list) {
+		struct commit_list *to_free = NULL;
+		commit = list->item;
+		if (process_ranges_arbitrary_commit(rev, commit)) {
+			*pp = list;
+			pp = &list->next;
+		} else
+			to_free = list;
+		list = list->next;
+		free(to_free);
+	}
+	*pp = NULL;
+
+	for (list = out; list; list = list->next)
+		rewrite_parents(rev, list->item, line_log_rewrite_one);
+
+	rev->commits = out;
+
+	return 0;
+}