Merge branch 'msys2-strace'

Debugging support on MSYS2.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

compat/mingw.c

@@ -1431,6 +1431,7 @@ static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **deltaen
 	HANDLE cons;
 	const char *(*quote_arg)(const char *arg) =
 		is_msys2_sh(*argv) ? quote_arg_msys2 : quote_arg_msvc;
+	const char *strace_env;
 
 	do_unset_environment_variables();
 
@@ -1489,6 +1490,31 @@ static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **deltaen
 			free(quoted);
 	}
 
+	strace_env = getenv("GIT_STRACE_COMMANDS");
+	if (strace_env) {
+		char *p = path_lookup("strace.exe", 1);
+		if (!p)
+			return error("strace not found!");
+		if (xutftowcs_path(wcmd, p) < 0) {
+			free(p);
+			return -1;
+		}
+		free(p);
+		if (!strcmp("1", strace_env) ||
+		    !strcasecmp("yes", strace_env) ||
+		    !strcasecmp("true", strace_env))
+			strbuf_insert(&args, 0, "strace ", 7);
+		else {
+			const char *quoted = quote_arg(strace_env);
+			struct strbuf buf = STRBUF_INIT;
+			strbuf_addf(&buf, "strace -o %s ", quoted);
+			if (quoted != strace_env)
+				free((char *)quoted);
+			strbuf_insert(&args, 0, buf.buf, buf.len);
+			strbuf_release(&buf);
+		}
+	}
+
 	ALLOC_ARRAY(wargs, st_add(st_mult(2, args.len), 1));
 	xutftowcs(wargs, args.buf, 2 * args.len + 1);
 	strbuf_release(&args);