1 files changed, 719 insertions, 0 deletions

diff --git a/third_party/git/tree-diff.c b/third_party/git/tree-diff.c
new file mode 100644
index 0000000000..33ded7f8b3
--- /dev/null
+++ b/third_party/git/tree-diff.c
@@ -0,0 +1,719 @@
+/*
+ * Helper functions for tree diff generation
+ */
+#include "cache.h"
+#include "diff.h"
+#include "diffcore.h"
+#include "tree.h"
+
+/*
+ * internal mode marker, saying a tree entry != entry of tp[imin]
+ * (see ll_diff_tree_paths for what it means there)
+ *
+ * we will update/use/emit entry for diff only with it unset.
+ */
+#define S_IFXMIN_NEQ	S_DIFFTREE_IFXMIN_NEQ
+
+#define FAST_ARRAY_ALLOC(x, nr) do { \
+	if ((nr) <= 2) \
+		(x) = xalloca((nr) * sizeof(*(x))); \
+	else \
+		ALLOC_ARRAY((x), nr); \
+} while(0)
+#define FAST_ARRAY_FREE(x, nr) do { \
+	if ((nr) > 2) \
+		free((x)); \
+} while(0)
+
+static struct combine_diff_path *ll_diff_tree_paths(
+	struct combine_diff_path *p, const struct object_id *oid,
+	const struct object_id **parents_oid, int nparent,
+	struct strbuf *base, struct diff_options *opt);
+static int ll_diff_tree_oid(const struct object_id *old_oid,
+			    const struct object_id *new_oid,
+			    struct strbuf *base, struct diff_options *opt);
+
+/*
+ * Compare two tree entries, taking into account only path/S_ISDIR(mode),
+ * but not their sha1's.
+ *
+ * NOTE files and directories *always* compare differently, even when having
+ *      the same name - thanks to base_name_compare().
+ *
+ * NOTE empty (=invalid) descriptor(s) take part in comparison as +infty,
+ *      so that they sort *after* valid tree entries.
+ *
+ *      Due to this convention, if trees are scanned in sorted order, all
+ *      non-empty descriptors will be processed first.
+ */
+static int tree_entry_pathcmp(struct tree_desc *t1, struct tree_desc *t2)
+{
+	struct name_entry *e1, *e2;
+	int cmp;
+
+	/* empty descriptors sort after valid tree entries */
+	if (!t1->size)
+		return t2->size ? 1 : 0;
+	else if (!t2->size)
+		return -1;
+
+	e1 = &t1->entry;
+	e2 = &t2->entry;
+	cmp = base_name_compare(e1->path, tree_entry_len(e1), e1->mode,
+				e2->path, tree_entry_len(e2), e2->mode);
+	return cmp;
+}
+
+
+/*
+ * convert path -> opt->diff_*() callbacks
+ *
+ * emits diff to first parent only, and tells diff tree-walker that we are done
+ * with p and it can be freed.
+ */
+static int emit_diff_first_parent_only(struct diff_options *opt, struct combine_diff_path *p)
+{
+	struct combine_diff_parent *p0 = &p->parent[0];
+	if (p->mode && p0->mode) {
+		opt->change(opt, p0->mode, p->mode, &p0->oid, &p->oid,
+			1, 1, p->path, 0, 0);
+	}
+	else {
+		const struct object_id *oid;
+		unsigned int mode;
+		int addremove;
+
+		if (p->mode) {
+			addremove = '+';
+			oid = &p->oid;
+			mode = p->mode;
+		} else {
+			addremove = '-';
+			oid = &p0->oid;
+			mode = p0->mode;
+		}
+
+		opt->add_remove(opt, addremove, mode, oid, 1, p->path, 0);
+	}
+
+	return 0;	/* we are done with p */
+}
+
+
+/*
+ * Make a new combine_diff_path from path/mode/sha1
+ * and append it to paths list tail.
+ *
+ * Memory for created elements could be reused:
+ *
+ *	- if last->next == NULL, the memory is allocated;
+ *
+ *	- if last->next != NULL, it is assumed that p=last->next was returned
+ *	  earlier by this function, and p->next was *not* modified.
+ *	  The memory is then reused from p.
+ *
+ * so for clients,
+ *
+ * - if you do need to keep the element
+ *
+ *	p = path_appendnew(p, ...);
+ *	process(p);
+ *	p->next = NULL;
+ *
+ * - if you don't need to keep the element after processing
+ *
+ *	pprev = p;
+ *	p = path_appendnew(p, ...);
+ *	process(p);
+ *	p = pprev;
+ *	; don't forget to free tail->next in the end
+ *
+ * p->parent[] remains uninitialized.
+ */
+static struct combine_diff_path *path_appendnew(struct combine_diff_path *last,
+	int nparent, const struct strbuf *base, const char *path, int pathlen,
+	unsigned mode, const struct object_id *oid)
+{
+	struct combine_diff_path *p;
+	size_t len = st_add(base->len, pathlen);
+	size_t alloclen = combine_diff_path_size(nparent, len);
+
+	/* if last->next is !NULL - it is a pre-allocated memory, we can reuse */
+	p = last->next;
+	if (p && (alloclen > (intptr_t)p->next)) {
+		FREE_AND_NULL(p);
+	}
+
+	if (!p) {
+		p = xmalloc(alloclen);
+
+		/*
+		 * until we go to it next round, .next holds how many bytes we
+		 * allocated (for faster realloc - we don't need copying old data).
+		 */
+		p->next = (struct combine_diff_path *)(intptr_t)alloclen;
+	}
+
+	last->next = p;
+
+	p->path = (char *)&(p->parent[nparent]);
+	memcpy(p->path, base->buf, base->len);
+	memcpy(p->path + base->len, path, pathlen);
+	p->path[len] = 0;
+	p->mode = mode;
+	oidcpy(&p->oid, oid ? oid : &null_oid);
+
+	return p;
+}
+
+/*
+ * new path should be added to combine diff
+ *
+ * 3 cases on how/when it should be called and behaves:
+ *
+ *	 t, !tp		-> path added, all parents lack it
+ *	!t,  tp		-> path removed from all parents
+ *	 t,  tp		-> path modified/added
+ *			   (M for tp[i]=tp[imin], A otherwise)
+ */
+static struct combine_diff_path *emit_path(struct combine_diff_path *p,
+	struct strbuf *base, struct diff_options *opt, int nparent,
+	struct tree_desc *t, struct tree_desc *tp,
+	int imin)
+{
+	unsigned short mode;
+	const char *path;
+	const struct object_id *oid;
+	int pathlen;
+	int old_baselen = base->len;
+	int i, isdir, recurse = 0, emitthis = 1;
+
+	/* at least something has to be valid */
+	assert(t || tp);
+
+	if (t) {
+		/* path present in resulting tree */
+		oid = tree_entry_extract(t, &path, &mode);
+		pathlen = tree_entry_len(&t->entry);
+		isdir = S_ISDIR(mode);
+	} else {
+		/*
+		 * a path was removed - take path from imin parent. Also take
+		 * mode from that parent, to decide on recursion(1).
+		 *
+		 * 1) all modes for tp[i]=tp[imin] should be the same wrt
+		 *    S_ISDIR, thanks to base_name_compare().
+		 */
+		tree_entry_extract(&tp[imin], &path, &mode);
+		pathlen = tree_entry_len(&tp[imin].entry);
+
+		isdir = S_ISDIR(mode);
+		oid = NULL;
+		mode = 0;
+	}
+
+	if (opt->flags.recursive && isdir) {
+		recurse = 1;
+		emitthis = opt->flags.tree_in_recursive;
+	}
+
+	if (emitthis) {
+		int keep;
+		struct combine_diff_path *pprev = p;
+		p = path_appendnew(p, nparent, base, path, pathlen, mode, oid);
+
+		for (i = 0; i < nparent; ++i) {
+			/*
+			 * tp[i] is valid, if present and if tp[i]==tp[imin] -
+			 * otherwise, we should ignore it.
+			 */
+			int tpi_valid = tp && !(tp[i].entry.mode & S_IFXMIN_NEQ);
+
+			const struct object_id *oid_i;
+			unsigned mode_i;
+
+			p->parent[i].status =
+				!t ? DIFF_STATUS_DELETED :
+					tpi_valid ?
+						DIFF_STATUS_MODIFIED :
+						DIFF_STATUS_ADDED;
+
+			if (tpi_valid) {
+				oid_i = &tp[i].entry.oid;
+				mode_i = tp[i].entry.mode;
+			}
+			else {
+				oid_i = &null_oid;
+				mode_i = 0;
+			}
+
+			p->parent[i].mode = mode_i;
+			oidcpy(&p->parent[i].oid, oid_i);
+		}
+
+		keep = 1;
+		if (opt->pathchange)
+			keep = opt->pathchange(opt, p);
+
+		/*
+		 * If a path was filtered or consumed - we don't need to add it
+		 * to the list and can reuse its memory, leaving it as
+		 * pre-allocated element on the tail.
+		 *
+		 * On the other hand, if path needs to be kept, we need to
+		 * correct its .next to NULL, as it was pre-initialized to how
+		 * much memory was allocated.
+		 *
+		 * see path_appendnew() for details.
+		 */
+		if (!keep)
+			p = pprev;
+		else
+			p->next = NULL;
+	}
+
+	if (recurse) {
+		const struct object_id **parents_oid;
+
+		FAST_ARRAY_ALLOC(parents_oid, nparent);
+		for (i = 0; i < nparent; ++i) {
+			/* same rule as in emitthis */
+			int tpi_valid = tp && !(tp[i].entry.mode & S_IFXMIN_NEQ);
+
+			parents_oid[i] = tpi_valid ? &tp[i].entry.oid : NULL;
+		}
+
+		strbuf_add(base, path, pathlen);
+		strbuf_addch(base, '/');
+		p = ll_diff_tree_paths(p, oid, parents_oid, nparent, base, opt);
+		FAST_ARRAY_FREE(parents_oid, nparent);
+	}
+
+	strbuf_setlen(base, old_baselen);
+	return p;
+}
+
+static void skip_uninteresting(struct tree_desc *t, struct strbuf *base,
+			       struct diff_options *opt)
+{
+	enum interesting match;
+
+	while (t->size) {
+		match = tree_entry_interesting(opt->repo->index, &t->entry,
+					       base, 0, &opt->pathspec);
+		if (match) {
+			if (match == all_entries_not_interesting)
+				t->size = 0;
+			break;
+		}
+		update_tree_entry(t);
+	}
+}
+
+
+/*
+ * generate paths for combined diff D(sha1,parents_oid[])
+ *
+ * Resulting paths are appended to combine_diff_path linked list, and also, are
+ * emitted on the go via opt->pathchange() callback, so it is possible to
+ * process the result as batch or incrementally.
+ *
+ * The paths are generated scanning new tree and all parents trees
+ * simultaneously, similarly to what diff_tree() was doing for 2 trees.
+ * The theory behind such scan is as follows:
+ *
+ *
+ * D(T,P1...Pn) calculation scheme
+ * -------------------------------
+ *
+ * D(T,P1...Pn) = D(T,P1) ^ ... ^ D(T,Pn)	(regarding resulting paths set)
+ *
+ *	D(T,Pj)		- diff between T..Pj
+ *	D(T,P1...Pn)	- combined diff from T to parents P1,...,Pn
+ *
+ *
+ * We start from all trees, which are sorted, and compare their entries in
+ * lock-step:
+ *
+ *	 T     P1       Pn
+ *	 -     -        -
+ *	|t|   |p1|     |pn|
+ *	|-|   |--| ... |--|      imin = argmin(p1...pn)
+ *	| |   |  |     |  |
+ *	|-|   |--|     |--|
+ *	|.|   |. |     |. |
+ *	 .     .        .
+ *	 .     .        .
+ *
+ * at any time there could be 3 cases:
+ *
+ *	1)  t < p[imin];
+ *	2)  t > p[imin];
+ *	3)  t = p[imin].
+ *
+ * Schematic deduction of what every case means, and what to do, follows:
+ *
+ * 1)  t < p[imin]  ->  ∀j t ∉ Pj  ->  "+t" ∈ D(T,Pj)  ->  D += "+t";  t↓
+ *
+ * 2)  t > p[imin]
+ *
+ *     2.1) ∃j: pj > p[imin]  ->  "-p[imin]" ∉ D(T,Pj)  ->  D += ø;  ∀ pi=p[imin]  pi↓
+ *     2.2) ∀i  pi = p[imin]  ->  pi ∉ T  ->  "-pi" ∈ D(T,Pi)  ->  D += "-p[imin]";  ∀i pi↓
+ *
+ * 3)  t = p[imin]
+ *
+ *     3.1) ∃j: pj > p[imin]  ->  "+t" ∈ D(T,Pj)  ->  only pi=p[imin] remains to investigate
+ *     3.2) pi = p[imin]  ->  investigate δ(t,pi)
+ *      |
+ *      |
+ *      v
+ *
+ *     3.1+3.2) looking at δ(t,pi) ∀i: pi=p[imin] - if all != ø  ->
+ *
+ *                       ⎧δ(t,pi)  - if pi=p[imin]
+ *              ->  D += ⎨
+ *                       ⎩"+t"     - if pi>p[imin]
+ *
+ *
+ *     in any case t↓  ∀ pi=p[imin]  pi↓
+ *
+ *
+ * ~~~~~~~~
+ *
+ * NOTE
+ *
+ *	Usual diff D(A,B) is by definition the same as combined diff D(A,[B]),
+ *	so this diff paths generator can, and is used, for plain diffs
+ *	generation too.
+ *
+ *	Please keep attention to the common D(A,[B]) case when working on the
+ *	code, in order not to slow it down.
+ *
+ * NOTE
+ *	nparent must be > 0.
+ */
+
+
+/* ∀ pi=p[imin]  pi↓ */
+static inline void update_tp_entries(struct tree_desc *tp, int nparent)
+{
+	int i;
+	for (i = 0; i < nparent; ++i)
+		if (!(tp[i].entry.mode & S_IFXMIN_NEQ))
+			update_tree_entry(&tp[i]);
+}
+
+static struct combine_diff_path *ll_diff_tree_paths(
+	struct combine_diff_path *p, const struct object_id *oid,
+	const struct object_id **parents_oid, int nparent,
+	struct strbuf *base, struct diff_options *opt)
+{
+	struct tree_desc t, *tp;
+	void *ttree, **tptree;
+	int i;
+
+	FAST_ARRAY_ALLOC(tp, nparent);
+	FAST_ARRAY_ALLOC(tptree, nparent);
+
+	/*
+	 * load parents first, as they are probably already cached.
+	 *
+	 * ( log_tree_diff() parses commit->parent before calling here via
+	 *   diff_tree_oid(parent, commit) )
+	 */
+	for (i = 0; i < nparent; ++i)
+		tptree[i] = fill_tree_descriptor(opt->repo, &tp[i], parents_oid[i]);
+	ttree = fill_tree_descriptor(opt->repo, &t, oid);
+
+	/* Enable recursion indefinitely */
+	opt->pathspec.recursive = opt->flags.recursive;
+
+	for (;;) {
+		int imin, cmp;
+
+		if (diff_can_quit_early(opt))
+			break;
+
+		if (opt->pathspec.nr) {
+			skip_uninteresting(&t, base, opt);
+			for (i = 0; i < nparent; i++)
+				skip_uninteresting(&tp[i], base, opt);
+		}
+
+		/* comparing is finished when all trees are done */
+		if (!t.size) {
+			int done = 1;
+			for (i = 0; i < nparent; ++i)
+				if (tp[i].size) {
+					done = 0;
+					break;
+				}
+			if (done)
+				break;
+		}
+
+		/*
+		 * lookup imin = argmin(p1...pn),
+		 * mark entries whether they =p[imin] along the way
+		 */
+		imin = 0;
+		tp[0].entry.mode &= ~S_IFXMIN_NEQ;
+
+		for (i = 1; i < nparent; ++i) {
+			cmp = tree_entry_pathcmp(&tp[i], &tp[imin]);
+			if (cmp < 0) {
+				imin = i;
+				tp[i].entry.mode &= ~S_IFXMIN_NEQ;
+			}
+			else if (cmp == 0) {
+				tp[i].entry.mode &= ~S_IFXMIN_NEQ;
+			}
+			else {
+				tp[i].entry.mode |= S_IFXMIN_NEQ;
+			}
+		}
+
+		/* fixup markings for entries before imin */
+		for (i = 0; i < imin; ++i)
+			tp[i].entry.mode |= S_IFXMIN_NEQ;	/* pi > p[imin] */
+
+
+
+		/* compare t vs p[imin] */
+		cmp = tree_entry_pathcmp(&t, &tp[imin]);
+
+		/* t = p[imin] */
+		if (cmp == 0) {
+			/* are either pi > p[imin] or diff(t,pi) != ø ? */
+			if (!opt->flags.find_copies_harder) {
+				for (i = 0; i < nparent; ++i) {
+					/* p[i] > p[imin] */
+					if (tp[i].entry.mode & S_IFXMIN_NEQ)
+						continue;
+
+					/* diff(t,pi) != ø */
+					if (!oideq(&t.entry.oid, &tp[i].entry.oid) ||
+					    (t.entry.mode != tp[i].entry.mode))
+						continue;
+
+					goto skip_emit_t_tp;
+				}
+			}
+
+			/* D += {δ(t,pi) if pi=p[imin];  "+a" if pi > p[imin]} */
+			p = emit_path(p, base, opt, nparent,
+					&t, tp, imin);
+
+		skip_emit_t_tp:
+			/* t↓,  ∀ pi=p[imin]  pi↓ */
+			update_tree_entry(&t);
+			update_tp_entries(tp, nparent);
+		}
+
+		/* t < p[imin] */
+		else if (cmp < 0) {
+			/* D += "+t" */
+			p = emit_path(p, base, opt, nparent,
+					&t, /*tp=*/NULL, -1);
+
+			/* t↓ */
+			update_tree_entry(&t);
+		}
+
+		/* t > p[imin] */
+		else {
+			/* ∀i pi=p[imin] -> D += "-p[imin]" */
+			if (!opt->flags.find_copies_harder) {
+				for (i = 0; i < nparent; ++i)
+					if (tp[i].entry.mode & S_IFXMIN_NEQ)
+						goto skip_emit_tp;
+			}
+
+			p = emit_path(p, base, opt, nparent,
+					/*t=*/NULL, tp, imin);
+
+		skip_emit_tp:
+			/* ∀ pi=p[imin]  pi↓ */
+			update_tp_entries(tp, nparent);
+		}
+	}
+
+	free(ttree);
+	for (i = nparent-1; i >= 0; i--)
+		free(tptree[i]);
+	FAST_ARRAY_FREE(tptree, nparent);
+	FAST_ARRAY_FREE(tp, nparent);
+
+	return p;
+}
+
+struct combine_diff_path *diff_tree_paths(
+	struct combine_diff_path *p, const struct object_id *oid,
+	const struct object_id **parents_oid, int nparent,
+	struct strbuf *base, struct diff_options *opt)
+{
+	p = ll_diff_tree_paths(p, oid, parents_oid, nparent, base, opt);
+
+	/*
+	 * free pre-allocated last element, if any
+	 * (see path_appendnew() for details about why)
+	 */
+	FREE_AND_NULL(p->next);
+
+	return p;
+}
+
+/*
+ * Does it look like the resulting diff might be due to a rename?
+ *  - single entry
+ *  - not a valid previous file
+ */
+static inline int diff_might_be_rename(void)
+{
+	return diff_queued_diff.nr == 1 &&
+		!DIFF_FILE_VALID(diff_queued_diff.queue[0]->one);
+}
+
+static void try_to_follow_renames(const struct object_id *old_oid,
+				  const struct object_id *new_oid,
+				  struct strbuf *base, struct diff_options *opt)
+{
+	struct diff_options diff_opts;
+	struct diff_queue_struct *q = &diff_queued_diff;
+	struct diff_filepair *choice;
+	int i;
+
+	/*
+	 * follow-rename code is very specific, we need exactly one
+	 * path. Magic that matches more than one path is not
+	 * supported.
+	 */
+	GUARD_PATHSPEC(&opt->pathspec, PATHSPEC_FROMTOP | PATHSPEC_LITERAL);
+#if 0
+	/*
+	 * We should reject wildcards as well. Unfortunately we
+	 * haven't got a reliable way to detect that 'foo\*bar' in
+	 * fact has no wildcards. nowildcard_len is merely a hint for
+	 * optimization. Let it slip for now until wildmatch is taught
+	 * about dry-run mode and returns wildcard info.
+	 */
+	if (opt->pathspec.has_wildcard)
+		die("BUG:%s:%d: wildcards are not supported",
+		    __FILE__, __LINE__);
+#endif
+
+	/* Remove the file creation entry from the diff queue, and remember it */
+	choice = q->queue[0];
+	q->nr = 0;
+
+	repo_diff_setup(opt->repo, &diff_opts);
+	diff_opts.flags.recursive = 1;
+	diff_opts.flags.find_copies_harder = 1;
+	diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
+	diff_opts.single_follow = opt->pathspec.items[0].match;
+	diff_opts.break_opt = opt->break_opt;
+	diff_opts.rename_score = opt->rename_score;
+	diff_setup_done(&diff_opts);
+	ll_diff_tree_oid(old_oid, new_oid, base, &diff_opts);
+	diffcore_std(&diff_opts);
+	clear_pathspec(&diff_opts.pathspec);
+
+	/* Go through the new set of filepairing, and see if we find a more interesting one */
+	opt->found_follow = 0;
+	for (i = 0; i < q->nr; i++) {
+		struct diff_filepair *p = q->queue[i];
+
+		/*
+		 * Found a source? Not only do we use that for the new
+		 * diff_queued_diff, we will also use that as the path in
+		 * the future!
+		 */
+		if ((p->status == 'R' || p->status == 'C') &&
+		    !strcmp(p->two->path, opt->pathspec.items[0].match)) {
+			const char *path[2];
+
+			/* Switch the file-pairs around */
+			q->queue[i] = choice;
+			choice = p;
+
+			/* Update the path we use from now on.. */
+			path[0] = p->one->path;
+			path[1] = NULL;
+			clear_pathspec(&opt->pathspec);
+			parse_pathspec(&opt->pathspec,
+				       PATHSPEC_ALL_MAGIC & ~PATHSPEC_LITERAL,
+				       PATHSPEC_LITERAL_PATH, "", path);
+
+			/*
+			 * The caller expects us to return a set of vanilla
+			 * filepairs to let a later call to diffcore_std()
+			 * it makes to sort the renames out (among other
+			 * things), but we already have found renames
+			 * ourselves; signal diffcore_std() not to muck with
+			 * rename information.
+			 */
+			opt->found_follow = 1;
+			break;
+		}
+	}
+
+	/*
+	 * Then, discard all the non-relevant file pairs...
+	 */
+	for (i = 0; i < q->nr; i++) {
+		struct diff_filepair *p = q->queue[i];
+		diff_free_filepair(p);
+	}
+
+	/*
+	 * .. and re-instate the one we want (which might be either the
+	 * original one, or the rename/copy we found)
+	 */
+	q->queue[0] = choice;
+	q->nr = 1;
+}
+
+static int ll_diff_tree_oid(const struct object_id *old_oid,
+			    const struct object_id *new_oid,
+			    struct strbuf *base, struct diff_options *opt)
+{
+	struct combine_diff_path phead, *p;
+	pathchange_fn_t pathchange_old = opt->pathchange;
+
+	phead.next = NULL;
+	opt->pathchange = emit_diff_first_parent_only;
+	diff_tree_paths(&phead, new_oid, &old_oid, 1, base, opt);
+
+	for (p = phead.next; p;) {
+		struct combine_diff_path *pprev = p;
+		p = p->next;
+		free(pprev);
+	}
+
+	opt->pathchange = pathchange_old;
+	return 0;
+}
+
+int diff_tree_oid(const struct object_id *old_oid,
+		  const struct object_id *new_oid,
+		  const char *base_str, struct diff_options *opt)
+{
+	struct strbuf base;
+	int retval;
+
+	strbuf_init(&base, PATH_MAX);
+	strbuf_addstr(&base, base_str);
+
+	retval = ll_diff_tree_oid(old_oid, new_oid, &base, opt);
+	if (!*base_str && opt->flags.follow_renames && diff_might_be_rename())
+		try_to_follow_renames(old_oid, new_oid, &base, opt);
+
+	strbuf_release(&base);
+
+	return retval;
+}
+
+int diff_root_tree_oid(const struct object_id *new_oid, const char *base, struct diff_options *opt)
+{
+	return diff_tree_oid(NULL, new_oid, base, opt);
+}