Fix null dereferences on unset %(fileargs)

src/argv.c

@@ -361,7 +361,7 @@ format_append_argv(struct format_context *format, const char ***dst_argv, const
 	int argc;
 
 	if (!src_argv)
-		return argv_append(dst_argv, "");
+		return true;
 
 	for (argc = 0; src_argv[argc]; argc++)
 		if (!format_append_arg(format, dst_argv, src_argv[argc]))
@@ -472,7 +472,17 @@ argv_format(struct argv_env *argv_env, const char ***dst_argv, const char *src_a
 		}
 	}
 
-	return src_argv[argc] == NULL;
+	if (src_argv[argc] != NULL)
+		return false;
+
+	// Make sure to return an argv-style array even if we have not formatted anything.
+	if (!*dst_argv) {
+		if (!argv_realloc(dst_argv, 1, 1))
+			return false;
+		(*dst_argv)[0] = NULL;
+	}
+
+	return true;
 }
 
 static inline bool

src/prompt.c

@@ -942,7 +942,7 @@ run_prompt_command(struct view *view, const char *argv[])
 		copied = argv_format(view->env, &next->argv, argv, false, true);
 		argv[0] = cmd;
 
-		if (!copied) {
+		if (!copied || !next->argv[0]) {
 			report("Argument formatting failed");
 		} else {
 			/* When running random commands, initially show the
@@ -966,7 +966,6 @@ run_prompt_command(struct view *view, const char *argv[])
 		char text[SIZEOF_STR] = "";
 
 		if (argv[1]
-		    && strlen(argv[1]) > 0
 		    && (!argv_format(view->env, &fmt_argv, &argv[1], false, true)
 			|| !argv_to_string(fmt_argv, text, sizeof(text), " ")
 			)) {
@@ -1103,7 +1102,7 @@ exec_run_request(struct view *view, struct run_request *req)
 	if (!argv_to_string(req->argv, cmd, sizeof(cmd), " ")
 	    || !argv_from_string_no_quotes(req_argv, &req_argc, cmd)
 	    || !argv_format(view->env, &argv, req_argv, false, true)
-	    || !argv) {
+	    || !argv[0]) {
 		report("Failed to format arguments");
 		return REQ_NONE;
 	}

test/regressions/github-1136-test

@@ -13,21 +13,54 @@ test_case bang-cmdlineargs-doesnt-crash \
 	--script='
 	:!%(cmdlineargs)
 	' <<EOF
+On branch master
+Changes to be committed:
+  (no files)
+Changes not staged for commit:
+  (no files)
+Untracked files:
+  (no files)
 
+[status] Nothing to update                                                  100%
+EOF
 
+test_case echo-cmdlineargs-doesnt-crash \
+	--args='status' \
+	--script='
+	:echo %(cmdlineargs)
+	' <<EOF
+On branch master
+Changes to be committed:
+  (no files)
+Changes not staged for commit:
+  (no files)
+Untracked files:
+  (no files)
 
+[status] Nothing to update                                                  100%
+EOF
 
+# This runs an empty command, hence the empty pager.
+test_case bang-fileargs-doesnt-crash \
+	--args='status' \
+	--script='
+	:!%(fileargs)
+	' <<EOF
+On branch master
+Changes to be committed:
+  (no files)
+Changes not staged for commit:
+  (no files)
+Untracked files:
+  (no files)
 
-
-
-
-[pager]                                                                       0%
+[status] Nothing to update                                                  100%
 EOF
 
-test_case echo-cmdlineargs-doesnt-crash \
+test_case echo-fileargs-doesnt-crash \
 	--args='status' \
 	--script='
-	:echo %(cmdlineargs)
+	:echo %(fileargs)
 	' <<EOF
 On branch master
 Changes to be committed: