alias: use run_command api to execute aliases

On Windows, system() executes with cmd.exe instead of /bin/sh. This
means that aliases currently has to be batch-scripts instead of
bourne-scripts. On top of that, cmd.exe does not handle single quotes,
which is what the code-path currently uses to handle arguments with
spaces.

To solve both problems in one go, use run_command_v_opt() to execute
the alias. It already does the right thing prepend "sh -c " to the
alias.

Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git.c

@@ -177,24 +177,24 @@ static int handle_alias(int *argcp, const char ***argv)
 	alias_string = alias_lookup(alias_command);
 	if (alias_string) {
 		if (alias_string[0] == '!') {
+			const char **alias_argv;
+			int argc = *argcp, i;
+
 			commit_pager_choice();
-			if (*argcp > 1) {
-				struct strbuf buf;
-
-				strbuf_init(&buf, PATH_MAX);
-				strbuf_addstr(&buf, alias_string);
-				sq_quote_argv(&buf, (*argv) + 1, PATH_MAX);
-				free(alias_string);
-				alias_string = buf.buf;
-			}
-			trace_printf("trace: alias to shell cmd: %s => %s\n",
-				     alias_command, alias_string + 1);
-			ret = system(alias_string + 1);
-			if (ret >= 0 && WIFEXITED(ret) &&
-			    WEXITSTATUS(ret) != 127)
-				exit(WEXITSTATUS(ret));
-			die("Failed to run '%s' when expanding alias '%s'",
-			    alias_string + 1, alias_command);
+
+			/* build alias_argv */
+			alias_argv = xmalloc(sizeof(*alias_argv) * (argc + 1));
+			alias_argv[0] = alias_string + 1;
+			for (i = 1; i < argc; ++i)
+				alias_argv[i] = (*argv)[i];
+			alias_argv[argc] = NULL;
+
+			ret = run_command_v_opt(alias_argv, RUN_USING_SHELL);
+			if (ret >= 0)   /* normal exit */
+				exit(ret);
+
+			die_errno("While expanding alias '%s': '%s'",
+			    alias_command, alias_string + 1);
 		}
 		count = split_cmdline(alias_string, &new_argv);
 		if (count < 0)