blame: ignore revs in .git-blame-ignore-revs by default

Documentation/blame-options.adoc

@@ -132,9 +132,12 @@ take effect.
 `--ignore-revs-file <file>`::
 	Ignore revisions listed in _<file>_, which must be in the same format as an
 	`fsck.skipList`.  This option may be repeated, and these files will be
-	processed after any files specified with the `blame.ignoreRevsFile` config
-	option.  An empty file name, `""`, will clear the list of revs from
-	previously processed files.
+	processed after the default `.git-blame-ignore-revs` file at the root of
+	the working tree (or `HEAD:.git-blame-ignore-revs` in a bare repository),
+	if it exists, and any files specified with the `blame.ignoreRevsFile`
+	configuration variable.  An empty file name, `""`, or
+	`--no-ignore-revs-file` will clear the list of revs from previously
+	processed files, including the default ignore-revs file.
 
 `--color-lines`::
 	Color line annotations in the default format differently if they come from

Documentation/config/blame.adoc

@@ -23,9 +23,13 @@ blame.showRoot::
 blame.ignoreRevsFile::
 	Ignore revisions listed in the file, one unabbreviated object name per
 	line, in linkgit:git-blame[1].  Whitespace and comments beginning with
-	`#` are ignored.  This option may be repeated multiple times.  Empty
-	file names will reset the list of ignored revisions.  This option will
-	be handled before the command line option `--ignore-revs-file`.
+	`#` are ignored.  If `.git-blame-ignore-revs` exists at the root of the
+	working tree (or `HEAD:.git-blame-ignore-revs` in a bare repository), it
+	is added as the initial element in the list of ignore-revs files.
+	Other files listed in the configuration are also used, but an empty
+	element makes all elements that appeared before in the list forgotten.
+	This option will be handled before the command line option
+	`--ignore-revs-file`.
 
 blame.markUnblamableLines::
 	Mark lines that were changed by an ignored revision that we could not

builtin/blame.c

@@ -29,6 +29,7 @@
 #include "object-name.h"
 #include "odb.h"
 #include "pager.h"
+#include "path.h"
 #include "blame.h"
 #include "refs.h"
 #include "setup.h"
@@ -769,7 +770,7 @@ static int git_blame_config(const char *var, const char *value,
 		if (ret)
 			return ret;
 		if (str)
-			string_list_insert(&ignore_revs_file_list, str);
+			string_list_append(&ignore_revs_file_list, str);
 		free(str);
 		return 0;
 	}
@@ -911,36 +912,139 @@ static int is_a_rev(const char *name)
 static int peel_to_commit_oid(struct object_id *oid_ret, void *cbdata)
 {
 	struct repository *r = ((struct blame_scoreboard *)cbdata)->repo;
+	enum object_type expected_type = OBJ_ANY;
 	struct object_id oid;
 
 	oidcpy(&oid, oid_ret);
 	while (1) {
+		unsigned flags = OBJECT_INFO_LOOKUP_REPLACE |
+				 OBJECT_INFO_SKIP_FETCH_OBJECT |
+				 OBJECT_INFO_QUICK;
+		struct object_info oi = OBJECT_INFO_INIT;
+		enum object_type kind;
 		struct object *obj;
-		int kind = odb_read_object_info(r->objects, &oid, NULL);
+
+		oi.typep = &kind;
+		if (odb_read_object_info_extended(r->objects, &oid, &oi,
+						  flags) < 0)
+			return -1;
+		if (expected_type != OBJ_ANY && kind != expected_type)
+			return -1;
 		if (kind == OBJ_COMMIT) {
 			oidcpy(oid_ret, &oid);
 			return 0;
 		}
 		if (kind != OBJ_TAG)
 			return -1;
-		obj = deref_tag(r, parse_object(r, &oid), NULL, 0);
+		obj = parse_object(r, &oid);
+		if (!obj || obj->type != OBJ_TAG)
+			return -1;
+		obj = ((struct tag *)obj)->tagged;
 		if (!obj)
 			return -1;
+		expected_type = obj->type;
 		oidcpy(&oid, &obj->oid);
 	}
 }
 
+#define IGNORE_REVS_MAX_FILE_SIZE (100 * 1024 * 1024)
+
+static void parse_default_ignore_revs_blob(struct blame_scoreboard *sb,
+					   const char *path)
+{
+	char *name = xstrfmt("HEAD:%s", path);
+	struct object_context oc;
+	struct object_id oid;
+	enum object_type type;
+	size_t size;
+	char *buf;
+
+	if (get_oid_with_context(sb->repo, name, GET_OID_QUIETLY,
+				 &oid, &oc))
+		goto out;
+	if (!S_ISREG(oc.mode))
+		goto out;
+
+	if (odb_read_object_info(sb->repo->objects, &oid, &size) != OBJ_BLOB)
+		goto out;
+	if (size >= IGNORE_REVS_MAX_FILE_SIZE) {
+		warning(_("ignoring overly large ignore-revs blob '%s'"), name);
+		goto out;
+	}
+
+	buf = odb_read_object(sb->repo->objects, &oid, &type, &size);
+	if (!buf)
+		goto out;
+	if (type == OBJ_BLOB)
+		oidset_parse_buffer_carefully(&sb->ignore_list, buf, size,
+					      sb->repo->hash_algo,
+					      peel_to_commit_oid, sb);
+	free(buf);
+
+out:
+	object_context_release(&oc);
+	free(name);
+}
+
+static void parse_default_ignore_revs_file(struct blame_scoreboard *sb,
+					   const char *name)
+{
+	char *path = repo_worktree_path(sb->repo, "%s", name);
+	struct stat st;
+	int fd = -1;
+	size_t size;
+	char *buf = NULL;
+
+	if (lstat(path, &st) || !S_ISREG(st.st_mode))
+		goto out;
+	fd = open_nofollow(path, O_RDONLY);
+	if (fd < 0 || fstat(fd, &st) || !S_ISREG(st.st_mode))
+		goto out;
+	if (st.st_size >= IGNORE_REVS_MAX_FILE_SIZE) {
+		warning(_("ignoring overly large ignore-revs file '%s'"), name);
+		goto out;
+	}
+	size = xsize_t(st.st_size);
+	buf = xmalloc(size);
+	if (read_in_full(fd, buf, size) == (ssize_t)size)
+		oidset_parse_buffer_carefully(&sb->ignore_list, buf, size,
+					      sb->repo->hash_algo,
+					      peel_to_commit_oid, sb);
+
+out:
+	if (fd >= 0)
+		close(fd);
+	free(buf);
+	free(path);
+}
+
+static void parse_default_ignore_revs(struct blame_scoreboard *sb,
+				      const char *name)
+{
+	if (repo_get_work_tree(sb->repo))
+		parse_default_ignore_revs_file(sb, name);
+	else
+		parse_default_ignore_revs_blob(sb, name);
+}
+
 static void build_ignorelist(struct blame_scoreboard *sb,
 			     struct string_list *ignore_revs_file_list,
 			     struct string_list *ignore_rev_list)
 {
 	struct string_list_item *i;
 	struct object_id oid;
+	size_t start_idx = 0, idx;
+
+	for (idx = 0; idx < ignore_revs_file_list->nr; idx++) {
+		if (!*ignore_revs_file_list->items[idx].string)
+			start_idx = idx + 1;
+	}
 
 	oidset_init(&sb->ignore_list, 0);
-	for_each_string_list_item(i, ignore_revs_file_list) {
-		if (!strcmp(i->string, ""))
-			oidset_clear(&sb->ignore_list);
+	for (idx = start_idx; idx < ignore_revs_file_list->nr; idx++) {
+		i = &ignore_revs_file_list->items[idx];
+		if (i->util)
+			parse_default_ignore_revs(sb, i->string);
 		else
 			oidset_parse_file_carefully(&sb->ignore_list, i->string,
 						    the_repository->hash_algo,
@@ -1020,6 +1124,12 @@ int cmd_blame(int argc,
 	const char *const *opt_usage = cmd_is_annotate ? annotate_opt_usage : blame_opt_usage;
 
 	setup_default_color_by_age();
+	/*
+	 * An entry with a non-NULL .util member names the default
+	 * ignore-revs file at the project root; see build_ignorelist().
+	 */
+	string_list_append(&ignore_revs_file_list,
+			   ".git-blame-ignore-revs")->util = (void *)1;
 	repo_config(the_repository, git_blame_config, &output_option);
 	repo_init_revisions(the_repository, &revs, NULL);
 	revs.date_mode = blame_date_mode;

oidset.c

@@ -70,41 +70,76 @@ void oidset_parse_file(struct oidset *set, const char *path,
 	oidset_parse_file_carefully(set, path, algop, NULL, NULL);
 }
 
+static void parse_oidset_line(struct oidset *set, struct strbuf *sb,
+			      const struct git_hash_algo *algop,
+			      oidset_parse_tweak_fn fn, void *cbdata)
+{
+	const char *p;
+	const char *name;
+	struct object_id oid;
+
+	if (memchr(sb->buf, '\0', sb->len))
+		die("invalid object name: %s", sb->buf);
+
+	/*
+	 * Allow trailing comments, leading whitespace
+	 * (including before commits), and empty or whitespace
+	 * only lines.
+	 */
+	name = strchr(sb->buf, '#');
+	if (name)
+		strbuf_setlen(sb, name - sb->buf);
+	strbuf_trim(sb);
+	if (!sb->len)
+		return;
+
+	if (parse_oid_hex_algop(sb->buf, &oid, &p, algop) || *p != '\0')
+		die("invalid object name: %s", sb->buf);
+	if (fn && fn(&oid, cbdata))
+		return;
+	oidset_insert(set, &oid);
+}
+
 void oidset_parse_file_carefully(struct oidset *set, const char *path,
 				 const struct git_hash_algo *algop,
 				 oidset_parse_tweak_fn fn, void *cbdata)
 {
 	FILE *fp;
 	struct strbuf sb = STRBUF_INIT;
-	struct object_id oid;
 
 	fp = fopen(path, "r");
 	if (!fp)
 		die("could not open object name list: %s", path);
-	while (!strbuf_getline(&sb, fp)) {
-		const char *p;
-		const char *name;
-
-		/*
-		 * Allow trailing comments, leading whitespace
-		 * (including before commits), and empty or whitespace
-		 * only lines.
-		 */
-		name = strchr(sb.buf, '#');
-		if (name)
-			strbuf_setlen(&sb, name - sb.buf);
-		strbuf_trim(&sb);
-		if (!sb.len)
-			continue;
-
-		if (parse_oid_hex_algop(sb.buf, &oid, &p, algop) || *p != '\0')
-			die("invalid object name: %s", sb.buf);
-		if (fn && fn(&oid, cbdata))
-			continue;
-		oidset_insert(set, &oid);
-	}
+	while (!strbuf_getline(&sb, fp))
+		parse_oidset_line(set, &sb, algop, fn, cbdata);
 	if (ferror(fp))
 		die_errno("Could not read '%s'", path);
 	fclose(fp);
 	strbuf_release(&sb);
 }
+
+void oidset_parse_buffer_carefully(struct oidset *set, const char *buf,
+				   size_t size,
+				   const struct git_hash_algo *algop,
+				   oidset_parse_tweak_fn fn, void *cbdata)
+{
+	struct strbuf sb = STRBUF_INIT;
+	const char *p = buf, *end;
+
+	if (!size)
+		return;
+	end = buf + size;
+
+	while (p < end) {
+		const char *nl = memchr(p, '\n', end - p);
+		size_t len = (nl ? nl : end) - p;
+
+		strbuf_reset(&sb);
+		if (len && p[len - 1] == '\r')
+			len--;
+		strbuf_add(&sb, p, len);
+		parse_oidset_line(set, &sb, algop, fn, cbdata);
+		p = nl ? nl + 1 : end;
+	}
+	strbuf_release(&sb);
+}

oidset.h

@@ -98,6 +98,15 @@ void oidset_parse_file_carefully(struct oidset *set, const char *path,
 				 const struct git_hash_algo *algop,
 				 oidset_parse_tweak_fn fn, void *cbdata);
 
+/*
+ * Similar to oidset_parse_file_carefully(), but parses lines from an
+ * in-memory buffer of 'size' bytes.
+ */
+void oidset_parse_buffer_carefully(struct oidset *set, const char *buf,
+				   size_t size,
+				   const struct git_hash_algo *algop,
+				   oidset_parse_tweak_fn fn, void *cbdata);
+
 struct oidset_iter {
 	const kh_oid_set_t *set;
 	khiter_t iter;