protocol: Add explicit nullable types

Most of the time it does not make sense to pass a NULL object, string, or array
to a protocol request. This commit adds an explicit “allow-null” attribute
to mark the request arguments where NULL makes sense.

Passing a NULL object, string, or array to a protocol request which is not
marked as allow-null is now an error. An implementation will never receive
a NULL value for these arguments from a client.

Signed-off-by: Christopher James Halse Rogers <christopher.halse.rogers@canonical.com>

diff --git a/src/connection.c b/src/connection.c
index 72ca908..5946556 100644 (file)
--- a/src/connection.c
+++ b/src/connection.c
@@ -404,6 +404,36 @@ wl_connection_put_fd(struct wl_connection *connection, int32_t fd)
        return 0;
 }
 
+struct argument_details {
+       char type;
+       int nullable;
+};
+
+static const char *
+get_next_argument(const char *signature, struct argument_details *details)
+{
+       if (*signature == '?') {
+               details->nullable = 1;
+               signature++;
+       } else
+               details->nullable = 0;
+
+       details->type = *signature;
+       return signature + 1;
+}
+
+static int
+arg_count_for_signature(const char *signature)
+{
+       int count = 0;
+       while (*signature) {
+               if (*signature != '?')
+                       count++;
+               signature++;
+       }
+       return count;
+}
+
 struct wl_closure *
 wl_closure_vmarshal(struct wl_object *sender,
                    uint32_t opcode, va_list ap,
@@ -415,6 +445,8 @@ wl_closure_vmarshal(struct wl_object *sender,
        int dup_fd;
        struct wl_array **arrayp, *array;
        const char **sp, *s;
+       const char *signature = message->signature;
+       struct argument_details arg;
        char *extra;
        int i, count, fd, extra_size, *fd_ptr;
 
@@ -424,7 +456,7 @@ wl_closure_vmarshal(struct wl_object *sender,
                return NULL;
 
        extra_size = wl_message_size_extra(message);
-       count = strlen(message->signature) + 2;
+       count = arg_count_for_signature(signature) + 2;
        extra = (char *) closure->buffer;
        start = &closure->buffer[DIV_ROUNDUP(extra_size, sizeof *p)];
        end = &closure->buffer[256];
@@ -434,7 +466,9 @@ wl_closure_vmarshal(struct wl_object *sender,
        closure->types[1] = &ffi_type_pointer;
 
        for (i = 2; i < count; i++) {
-               switch (message->signature[i - 2]) {
+               signature = get_next_argument(signature, &arg);
+
+               switch (arg.type) {
                case 'f':
                        closure->types[i] = &ffi_type_sint32;
                        closure->args[i] = p;
@@ -463,6 +497,10 @@ wl_closure_vmarshal(struct wl_object *sender,
                        extra += sizeof *sp;
 
                        s = va_arg(ap, const char *);
+
+                       if (!arg.nullable && s == NULL)
+                               goto err_null;
+
                        length = s ? strlen(s) + 1: 0;
                        if (p + DIV_ROUNDUP(length, sizeof *p) + 1 > end)
                                goto err;
@@ -483,6 +521,10 @@ wl_closure_vmarshal(struct wl_object *sender,
                        extra += sizeof *objectp;
 
                        object = va_arg(ap, struct wl_object *);
+
+                       if (!arg.nullable && object == NULL)
+                               goto err_null;
+
                        *objectp = object;
                        if (end - p < 1)
                                goto err;
@@ -508,6 +550,10 @@ wl_closure_vmarshal(struct wl_object *sender,
                        extra += sizeof **arrayp;
 
                        array = va_arg(ap, struct wl_array *);
+
+                       if (!arg.nullable && array == NULL)
+                               goto err_null;
+
                        if (array == NULL || array->size == 0) {
                                if (end - p < 1)
                                        goto err;
@@ -542,7 +588,7 @@ wl_closure_vmarshal(struct wl_object *sender,
                        break;
                default:
                        fprintf(stderr, "unhandled format code: '%c'\n",
-                               message->signature[i - 2]);
+                               arg.type);
                        assert(0);
                        break;
                }
@@ -567,6 +613,15 @@ err:
        errno = ENOMEM;
 
        return NULL;
+
+err_null:
+       free(closure);
+       wl_log("error marshalling arguments for %s:%i.%s (signature %s): "
+              "null value passed for arg %i\n",
+              sender->interface->name, sender->id, message->name,
+              message->signature, i);
+       errno = EINVAL;
+       return NULL;
 }
 
 struct wl_closure *
@@ -579,11 +634,13 @@ wl_connection_demarshal(struct wl_connection *connection,
        int *fd;
        char *extra, **s;
        unsigned int i, count, extra_space;
+       const char *signature = message->signature;
+       struct argument_details arg;
        struct wl_object **object;
        struct wl_array **array;
        struct wl_closure *closure;
 
-       count = strlen(message->signature) + 2;
+       count = arg_count_for_signature(signature) + 2;
        if (count > ARRAY_LENGTH(closure->types)) {
                printf("too many args (%d)\n", count);
                errno = EINVAL;
@@ -606,6 +663,8 @@ wl_connection_demarshal(struct wl_connection *connection,
        end = (uint32_t *) ((char *) p + size);
        extra = (char *) end;
        for (i = 2; i < count; i++) {
+               signature = get_next_argument(signature, &arg);
+
                if (p + 1 > end) {
                        printf("message too short, "
                               "object (%d), message %s(%s)\n",
@@ -614,7 +673,7 @@ wl_connection_demarshal(struct wl_connection *connection,
                        goto err;
                }
 
-               switch (message->signature[i - 2]) {
+               switch (arg.type) {
                case 'u':
                        closure->types[i] = &ffi_type_uint32;
                        closure->args[i] = p++;
@@ -784,11 +843,14 @@ copy_fds_to_connection(struct wl_closure *closure,
 {
        const struct wl_message *message = closure->message;
        uint32_t i, count;
+       struct argument_details arg;
+       const char *signature = message->signature;
        int *fd;
 
-       count = strlen(message->signature) + 2;
+       count = arg_count_for_signature(signature) + 2;
        for (i = 2; i < count; i++) {
-               if (message->signature[i - 2] != 'h')
+               signature = get_next_argument(signature, &arg);
+               if (arg.type != 'h')
                        continue;
 
                fd = closure->args[i];
@@ -834,6 +896,8 @@ wl_closure_print(struct wl_closure *closure, struct wl_object *target, int send)
        union wl_value *value;
        int32_t si;
        int i;
+       struct argument_details arg;
+       const char *signature = closure->message->signature;
        struct timespec tp;
        unsigned int time;
 
@@ -847,11 +911,12 @@ wl_closure_print(struct wl_closure *closure, struct wl_object *target, int send)
                closure->message->name);
 
        for (i = 2; i < closure->count; i++) {
+               signature = get_next_argument(signature, &arg);
                if (i > 2)
                        fprintf(stderr, ", ");
 
                value = closure->args[i];
-               switch (closure->message->signature[i - 2]) {
+               switch (arg.type) {
                case 'u':
                        fprintf(stderr, "%u", value->uint32);
                        break;

diff --git a/src/scanner.c b/src/scanner.c
index be8d3d6..4d4537c 100644 (file)
--- a/src/scanner.c
+++ b/src/scanner.c
@@ -93,6 +93,7 @@ enum arg_type {
 struct arg {
        char *name;
        enum arg_type type;
+       int nullable;
        char *interface_name;
        struct wl_list link;
        char *summary;
@@ -220,6 +221,20 @@ fail(struct parse_context *ctx, const char *msg)
        exit(EXIT_FAILURE);
 }
 
+static int
+is_nullable_type(struct arg *arg)
+{
+       switch (arg->type) {
+       /* Strings, objects, and arrays are possibly nullable */
+       case STRING:
+       case OBJECT:
+       case ARRAY:
+               return 1;
+       default:
+               return 0;
+       }
+}
+
 static void
 start_element(void *data, const char *element_name, const char **atts)
 {
@@ -231,6 +246,7 @@ start_element(void *data, const char *element_name, const char **atts)
        struct entry *entry;
        struct description *description;
        const char *name, *type, *interface_name, *value, *summary, *since;
+       const char *allow_null;
        char *end;
        int i, version;
 
@@ -242,6 +258,7 @@ start_element(void *data, const char *element_name, const char **atts)
        summary = NULL;
        description = NULL;
        since = NULL;
+       allow_null = NULL;
        for (i = 0; atts[i]; i += 2) {
                if (strcmp(atts[i], "name") == 0)
                        name = atts[i + 1];
@@ -257,6 +274,8 @@ start_element(void *data, const char *element_name, const char **atts)
                        summary = atts[i + 1];
                if (strcmp(atts[i], "since") == 0)
                        since = atts[i + 1];
+               if (strcmp(atts[i], "allow-null") == 0)
+                       allow_null = atts[i + 1];
        }
 
        ctx->character_data_length = 0;
@@ -364,6 +383,16 @@ start_element(void *data, const char *element_name, const char **atts)
                        break;
                }
 
+               if (allow_null == NULL || strcmp(allow_null, "false") == 0)
+                       arg->nullable = 0;
+               else if (strcmp(allow_null, "true") == 0)
+                       arg->nullable = 1;
+               else
+                       fail(ctx, "invalid value for allow-null attribute");
+
+               if (allow_null != NULL && !is_nullable_type(arg))
+                       fail(ctx, "allow-null is only valid for objects, strings, and arrays");
+
                arg->summary = NULL;
                if (summary)
                        arg->summary = strdup(summary);
@@ -969,6 +998,9 @@ emit_messages(struct wl_list *message_list,
        wl_list_for_each(m, message_list, link) {
                printf("\t{ \"%s\", \"", m->name);
                wl_list_for_each(a, &m->arg_list, link) {
+                       if (is_nullable_type(a) && a->nullable)
+                               printf("?");
+
                        switch (a->type) {
                        default:
                        case INT:

diff --git a/tests/connection-test.c b/tests/connection-test.c
index 066b4bc..a852c17 100644 (file)
--- a/tests/connection-test.c
+++ b/tests/connection-test.c
@@ -233,9 +233,6 @@ TEST(connection_marshal)
        marshal(&data, "o", 12, &object);
        assert(data.buffer[2] == object.id);
 
-       marshal(&data, "o", 12, NULL);
-       assert(data.buffer[2] == 0);
-
        marshal(&data, "n", 12, &object);
        assert(data.buffer[2] == object.id);
 
@@ -252,6 +249,68 @@ TEST(connection_marshal)
 }
 
 static void
+expected_fail_marshal(int expected_error, const char *format, ...)
+{
+       struct wl_closure *closure;
+       static const uint32_t opcode = 4444;
+       static const struct wl_interface test_interface = { 
+               .name = "test_object"
+       };
+       static struct wl_object sender = { 0 };
+       struct wl_message message = { "test", format, NULL };
+
+       sender.interface = &test_interface;
+       sender.id = 1234;
+       va_list ap;
+
+       va_start(ap, format);
+       closure = wl_closure_vmarshal(&sender, opcode, ap, &message);
+       va_end(ap);
+
+       assert(closure == NULL);
+       assert(errno == expected_error);
+}
+
+TEST(connection_marshal_nullables)
+{
+       struct marshal_data data;
+       struct wl_object object;
+       struct wl_array array;
+       const char text[] = "curry";
+
+       setup_marshal_data(&data);
+
+       expected_fail_marshal(EINVAL, "o", NULL);
+       expected_fail_marshal(EINVAL, "s", NULL);
+       expected_fail_marshal(EINVAL, "a", NULL);
+
+       marshal(&data, "?o", 12, NULL);
+       assert(data.buffer[2] == 0);
+
+       marshal(&data, "?a", 12, NULL);
+       assert(data.buffer[2] == 0);
+
+       marshal(&data, "?s", 12, NULL);
+       assert(data.buffer[2] == 0);
+
+       object.id = 55293;
+       marshal(&data, "?o", 12, &object);
+       assert(data.buffer[2] == object.id);
+
+       array.data = (void *) text;
+       array.size = sizeof text;
+       marshal(&data, "?a", 20, &array);
+       assert(data.buffer[2] == array.size);
+       assert(memcmp(&data.buffer[3], text, array.size) == 0);
+
+       marshal(&data, "?s", 20, text);
+       assert(data.buffer[2] == sizeof text);
+       assert(strcmp((char *) &data.buffer[3], text) == 0);
+
+       release_marshal_data(&data);
+}
+
+static void
 validate_demarshal_u(struct marshal_data *data,
                     struct wl_object *object, uint32_t u)
 {
@@ -269,7 +328,10 @@ static void
 validate_demarshal_s(struct marshal_data *data,
                     struct wl_object *object, const char *s)
 {
-       assert(strcmp(data->value.s, s) == 0);
+       if (data->value.s != NULL)
+               assert(strcmp(data->value.s, s) == 0);
+       else
+               assert(s == NULL);
 }
 
 static void
@@ -343,12 +405,25 @@ TEST(connection_demarshal)
        memcpy(&msg[3], data.value.s, msg[2]);
        demarshal(&data, "s", msg, (void *) validate_demarshal_s);
 
+       data.value.s = "superdude";
+       msg[0] = 400200;
+       msg[1] = 24;
+       msg[2] = 10;
+       memcpy(&msg[3], data.value.s, msg[2]);
+       demarshal(&data, "?s", msg, (void *) validate_demarshal_s);
+
        data.value.i = wl_fixed_from_double(-90000.2390);
        msg[0] = 400200;
        msg[1] = 12;
        msg[2] = data.value.i;
        demarshal(&data, "f", msg, (void *) validate_demarshal_f);
 
+       data.value.s = NULL;
+       msg[0] = 400200;
+       msg[1] = 12;
+       msg[2] = 0;
+       demarshal(&data, "?s", msg, (void *) validate_demarshal_s);     
+
        release_marshal_data(&data);
 }
 
@@ -408,6 +483,10 @@ TEST(connection_marshal_demarshal)
        marshal_demarshal(&data, (void *) validate_demarshal_s,
                          28, "s", data.value.s);
 
+       data.value.s = "cookie robots";
+       marshal_demarshal(&data, (void *) validate_demarshal_s,
+                         28, "?s", data.value.s);
+
        data.value.h = mkstemp(f);
        assert(data.value.h >= 0);
        marshal_demarshal(&data, (void *) validate_demarshal_h,