run_external_diff: use an argv_array for the environment

We currently use static buffers and a static array for
formatting the environment passed to the external diff.
There's nothing wrong in the code, but it is much easier to
verify that it is correct if we use a dynamic argv_array.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/diff.c b/diff.c
index 76ae3790324c6ef6007a939af9b82327130d1bd2..c7b433ffcd8a8df847ebfcd4b4a3e504059a4d73 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -2908,11 +2908,9 @@ static void run_external_diff(const char *pgm,
                              struct diff_options *o)
 {
        struct argv_array argv = ARGV_ARRAY_INIT;
+       struct argv_array env = ARGV_ARRAY_INIT;
        int retval;
        struct diff_queue_struct *q = &diff_queued_diff;
-       const char *env[3] = { NULL };
-       char env_counter[50];
-       char env_total[50];
 
        if (one && two) {
                struct diff_tempfile *temp_one, *temp_two;
@@ -2937,15 +2935,13 @@ static void run_external_diff(const char *pgm,
        }
        fflush(NULL);
 
-       env[0] = env_counter;
-       snprintf(env_counter, sizeof(env_counter), "GIT_DIFF_PATH_COUNTER=%d",
-                ++o->diff_path_counter);
-       env[1] = env_total;
-       snprintf(env_total, sizeof(env_total), "GIT_DIFF_PATH_TOTAL=%d", q->nr);
+       argv_array_pushf(&env, "GIT_DIFF_PATH_COUNTER=%d", ++o->diff_path_counter);
+       argv_array_pushf(&env, "GIT_DIFF_PATH_TOTAL=%d", q->nr);
 
-       retval = run_command_v_opt_cd_env(argv.argv, RUN_USING_SHELL, NULL, env);
+       retval = run_command_v_opt_cd_env(argv.argv, RUN_USING_SHELL, NULL, env.argv);
        remove_tempfile();
        argv_array_clear(&argv);
+       argv_array_clear(&env);
        if (retval) {
                fprintf(stderr, "external diff died, stopping at %s.\n", name);
                exit(1);