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protocol: Add explicit nullable types

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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>
This commit is contained in:
Christopher James Halse Rogers 2012-07-02 20:03:30 +10:00 • committed by Kristian Høgsberg
parent d2bcffc470
commit 161c690b55
3 changed files with 188 additions and 12 deletions
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32
src/scanner.c
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@ -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: