+static int is_valid_cmd_name(const char *cmd)
+{
+ /* Test command contains no . or / characters */
+ return cmd[strcspn(cmd, "./")] == '\0';
+}
+
+static char *make_cmd(const char *prog)
+{
+ char *prefix = xmalloc((strlen(prog) + strlen(COMMAND_DIR) + 2));
+ strcpy(prefix, COMMAND_DIR);
+ strcat(prefix, "/");
+ strcat(prefix, prog);
+ return prefix;
+}
+
+static void cd_to_homedir(void)
+{
+ const char *home = getenv("HOME");
+ if (!home)
+ die("could not determine user's home directory; HOME is unset");
+ if (chdir(home) == -1)
+ die("could not chdir to user's home directory");
+}
+
+static void run_shell(void)
+{
+ int done = 0;
+ static const char *help_argv[] = { HELP_COMMAND, NULL };
+ /* Print help if enabled */
+ run_command_v_opt(help_argv, RUN_SILENT_EXEC_FAILURE);
+
+ do {
+ struct strbuf line = STRBUF_INIT;
+ const char *prog;
+ char *full_cmd;
+ char *rawargs;
+ char *split_args;
+ const char **argv;
+ int code;
+ int count;
+
+ fprintf(stderr, "git> ");
+ if (strbuf_getline(&line, stdin, '\n') == EOF) {
+ fprintf(stderr, "\n");
+ strbuf_release(&line);
+ break;
+ }
+ strbuf_trim(&line);
+ rawargs = strbuf_detach(&line, NULL);
+ split_args = xstrdup(rawargs);
+ count = split_cmdline(split_args, &argv);
+ if (count < 0) {
+ fprintf(stderr, "invalid command format '%s': %s\n", rawargs,
+ split_cmdline_strerror(count));
+ free(split_args);
+ free(rawargs);
+ continue;
+ }
+
+ prog = argv[0];
+ if (!strcmp(prog, "")) {
+ } else if (!strcmp(prog, "quit") || !strcmp(prog, "logout") ||
+ !strcmp(prog, "exit") || !strcmp(prog, "bye")) {
+ done = 1;
+ } else if (is_valid_cmd_name(prog)) {
+ full_cmd = make_cmd(prog);
+ argv[0] = full_cmd;
+ code = run_command_v_opt(argv, RUN_SILENT_EXEC_FAILURE);
+ if (code == -1 && errno == ENOENT) {
+ fprintf(stderr, "unrecognized command '%s'\n", prog);
+ }
+ free(full_cmd);
+ } else {
+ fprintf(stderr, "invalid command format '%s'\n", prog);
+ }
+
+ free(argv);
+ free(rawargs);
+ } while (!done);
+}