config-parser: Add section iterator API

The X backend needs to iterate through all outputs.

shared/config-parser-test.c

@@ -75,6 +75,10 @@ static const char t1[] =
 	"color=red\n"
 	"contents=sand\n";
 
+static const char *section_names[] = {
+	"foo", "bar", "stuff", "bucket", "bucket"
+};
+
 static const char t2[] =
 	"# invalid section...\n"
 	"[this bracket isn't closed\n";
@@ -93,8 +97,9 @@ int main(int argc, char *argv[])
 {
 	struct weston_config *config;
 	struct weston_config_section *section;
+	const char *name;
 	char *s;
-	int r, b;
+	int r, b, i;
 	int32_t n;
 	uint32_t u;
 
@@ -170,6 +175,12 @@ int main(int argc, char *argv[])
 	assert(r == -1 && errno == ENOENT && strcmp(s, "eels") == 0);
 	free(s);
 
+	section = NULL;
+	i = 0;
+	while (weston_config_next_section(config, &section, &name))
+		assert(strcmp(section_names[i++], name) == 0);
+	assert(i == 5);
+
 	weston_config_destroy(config);
 
 	config = run_test(t2);

shared/config-parser.c

@@ -36,6 +36,10 @@
 #include <wayland-util.h>
 #include "config-parser.h"
 
+#define container_of(ptr, type, member) ({				\
+	const __typeof__( ((type *)0)->member ) *__mptr = (ptr);	\
+	(type *)( (char *)__mptr - offsetof(type,member) );})
+
 static int
 handle_key(const struct config_key *key, const char *value)
 {
@@ -472,6 +476,26 @@ weston_config_parse(int fd)
 	return config;
 }
 
+int
+weston_config_next_section(struct weston_config *config,
+			   struct weston_config_section **section,
+			   const char **name)
+{
+	if (*section == NULL)
+		*section = container_of(config->section_list.next,
+					struct weston_config_section, link);
+	else
+		*section = container_of((*section)->link.next,
+					struct weston_config_section, link);
+
+	if (&(*section)->link == &config->section_list)
+		return 0;
+
+	*name = (*section)->name;
+
+	return 1;
+}
+
 void
 weston_config_destroy(struct weston_config *config)
 {

shared/config-parser.h

@@ -102,6 +102,11 @@ weston_config_parse(int fd);
 void
 weston_config_destroy(struct weston_config *config);
 
+int weston_config_next_section(struct weston_config *config,
+			       struct weston_config_section **section,
+			       const char **name);
+
+
 #ifdef  __cplusplus
 }
 #endif