fast-import: permit reading multiple marks files

In the future, we'll want to read marks files for submodules as well.
Refactor the existing code to make it possible to read multiple marks
files, each into their own marks set.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: bk2204

fast-import.c

@@ -493,9 +493,8 @@ static char *pool_strdup(const char *s)
 	return r;
 }
 
-static void insert_mark(uintmax_t idnum, struct object_entry *oe)
+static void insert_mark(struct mark_set *s, uintmax_t idnum, struct object_entry *oe)
 {
-	struct mark_set *s = marks;
 	while ((idnum >> s->shift) >= 1024) {
 		s = mem_pool_calloc(&fi_mem_pool, 1, sizeof(struct mark_set));
 		s->shift = marks->shift + 10;
@@ -919,7 +918,7 @@ static int store_object(
 
 	e = insert_object(&oid);
 	if (mark)
-		insert_mark(mark, e);
+		insert_mark(marks, mark, e);
 	if (e->idx.offset) {
 		duplicate_count_by_type[type]++;
 		return 1;
@@ -1117,7 +1116,7 @@ static void stream_blob(uintmax_t len, struct object_id *oidout, uintmax_t mark)
 	e = insert_object(&oid);
 
 	if (mark)
-		insert_mark(mark, e);
+		insert_mark(marks, mark, e);
 
 	if (e->idx.offset) {
 		duplicate_count_by_type[OBJ_BLOB]++;
@@ -1712,16 +1711,9 @@ static void dump_marks(void)
 	}
 }
 
-static void read_marks(void)
+static void read_mark_file(struct mark_set *s, FILE *f)
 {
 	char line[512];
-	FILE *f = fopen(import_marks_file, "r");
-	if (f)
-		;
-	else if (import_marks_file_ignore_missing && errno == ENOENT)
-		goto done; /* Marks file does not exist */
-	else
-		die_errno("cannot read '%s'", import_marks_file);
 	while (fgets(line, sizeof(line), f)) {
 		uintmax_t mark;
 		char *end;
@@ -1747,8 +1739,20 @@ static void read_marks(void)
 			e->pack_id = MAX_PACK_ID;
 			e->idx.offset = 1; /* just not zero! */
 		}
-		insert_mark(mark, e);
+		insert_mark(s, mark, e);
 	}
+}
+
+static void read_marks(void)
+{
+	FILE *f = fopen(import_marks_file, "r");
+	if (f)
+		;
+	else if (import_marks_file_ignore_missing && errno == ENOENT)
+		goto done; /* Marks file does not exist */
+	else
+		die_errno("cannot read '%s'", import_marks_file);
+	read_mark_file(marks, f);
 	fclose(f);
 done:
 	import_marks_file_done = 1;
@@ -3130,7 +3134,7 @@ static void parse_alias(void)
 		die(_("Expected 'to' command, got %s"), command_buf.buf);
 	e = find_object(&b.oid);
 	assert(e);
-	insert_mark(next_mark, e);
+	insert_mark(marks, next_mark, e);
 }
 
 static char* make_fast_import_path(const char *path)