stat_tracking_info: convert to argv_array

In addition to dropping the magic number for the fixed-size
argv, we can also drop a fixed-length buffer and some
strcpy's into it.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

remote.c

@@ -8,6 +8,7 @@
 #include "tag.h"
 #include "string-list.h"
 #include "mergesort.h"
+#include "argv-array.h"
 
 enum map_direction { FROM_SRC, FROM_DST };
 
@@ -1997,10 +1998,9 @@ int stat_tracking_info(struct branch *branch, int *num_ours, int *num_theirs,
 {
 	unsigned char sha1[20];
 	struct commit *ours, *theirs;
-	char symmetric[84];
 	struct rev_info revs;
-	const char *rev_argv[10], *base;
-	int rev_argc;
+	const char *base;
+	struct argv_array argv = ARGV_ARRAY_INIT;
 
 	/* Cannot stat unless we are marked to build on top of somebody else. */
 	base = branch_get_upstream(branch, NULL);
@@ -2029,19 +2029,15 @@ int stat_tracking_info(struct branch *branch, int *num_ours, int *num_theirs,
 	}
 
 	/* Run "rev-list --left-right ours...theirs" internally... */
-	rev_argc = 0;
-	rev_argv[rev_argc++] = NULL;
-	rev_argv[rev_argc++] = "--left-right";
-	rev_argv[rev_argc++] = symmetric;
-	rev_argv[rev_argc++] = "--";
-	rev_argv[rev_argc] = NULL;
-
-	strcpy(symmetric, sha1_to_hex(ours->object.sha1));
-	strcpy(symmetric + 40, "...");
-	strcpy(symmetric + 43, sha1_to_hex(theirs->object.sha1));
+	argv_array_push(&argv, ""); /* ignored */
+	argv_array_push(&argv, "--left-right");
+	argv_array_pushf(&argv, "%s...%s",
+			 sha1_to_hex(ours->object.sha1),
+			 sha1_to_hex(theirs->object.sha1));
+	argv_array_push(&argv, "--");
 
 	init_revisions(&revs, NULL);
-	setup_revisions(rev_argc, rev_argv, &revs, NULL);
+	setup_revisions(argv.argc, argv.argv, &revs, NULL);
 	if (prepare_revision_walk(&revs))
 		die("revision walk setup failed");
 
@@ -2061,6 +2057,8 @@ int stat_tracking_info(struct branch *branch, int *num_ours, int *num_theirs,
 	/* clear object flags smudged by the above traversal */
 	clear_commit_marks(ours, ALL_REV_FLAGS);
 	clear_commit_marks(theirs, ALL_REV_FLAGS);
+
+	argv_array_clear(&argv);
 	return 0;
 }