libusbgx: Add support for OS Descriptor configuration bindings

OS Descriptors require an association to a single configuration. This
allows to use a specific configuration for hosts supporting  OS
Descriptors.

Signed-off-by: Stefan Agner <stefan.agner@toradex.com>
[Allow to also remove os desc binding]
Signed-off-by: Krzysztof Opasiak <k.opasiak@samsung.com>

4 files changed, 228 insertions, 0 deletions

diff --git a/include/usbg/usbg.h b/include/usbg/usbg.h
index 4b67f4e..2dc06ad 100644
--- a/include/usbg/usbg.h
+++ b/include/usbg/usbg.h
@@ -1004,6 +1004,21 @@ extern const char *usbg_get_binding_name(usbg_binding *b);
  */
 extern int usbg_get_binding_name_s(usbg_binding *b, char *buf, int len);
 
+/**
+ * @brief Get configuration selected for OS Descriptors
+ * @param g Pointer to gadget
+ * @return usbg_config or NULL
+ */
+usbg_config *usbg_get_os_desc_binding(usbg_gadget *g);
+
+/**
+ * @brief Set configuration for OS Descriptors
+ * @param g Pointer to gadget
+ * @param c Pointer to config
+ * @return 0 on success, usbg_error on failure.
+ */
+extern int usbg_set_os_desc_config(usbg_gadget *g, usbg_config *c);
+
 /* USB gadget setup and teardown */
 
 /**
diff --git a/include/usbg/usbg_internal.h b/include/usbg/usbg_internal.h
index cde3ad3..441df63 100644
--- a/include/usbg/usbg_internal.h
+++ b/include/usbg/usbg_internal.h
@@ -110,6 +110,7 @@ struct usbg_gadget
 	usbg_state *parent;
 	config_t *last_failed_import;
 	usbg_udc *udc;
+	usbg_config *os_desc_binding;
 };
 
 struct usbg_config
diff --git a/src/usbg.c b/src/usbg.c
index 090aea2..00fc55e 100644
--- a/src/usbg.c
+++ b/src/usbg.c
@@ -361,6 +361,7 @@ static usbg_gadget *usbg_allocate_gadget(const char *path, const char *name,
 	g->path = strdup(path);
 	g->parent = parent;
 	g->udc = NULL;
+	g->os_desc_binding = NULL;
 
 	if (!(g->name) || !(g->path))
 		goto cleanup;
@@ -645,6 +646,83 @@ out:
 	return ret;
 }
 
+static int usbg_parse_gadget_os_desc_binding(usbg_gadget *g)
+{
+	int i, n, nmb, id;
+	int ret = USBG_SUCCESS;
+	struct dirent **dent;
+	char bpath[USBG_MAX_PATH_LENGTH];
+	char target[USBG_MAX_PATH_LENGTH];
+	char *target_name;
+	usbg_config *c;
+	char *label = NULL;
+	int end;
+
+	end = snprintf(bpath, sizeof(bpath), "%s/%s/%s", g->path, g->name,
+			OS_DESC_DIR);
+	if (end >= sizeof(bpath)) {
+		ret = USBG_ERROR_PATH_TOO_LONG;
+		goto out;
+	}
+
+	n = scandir(bpath, &dent, bindings_select, alphasort);
+	if (n < 0) {
+		ret = usbg_translate_error(errno);
+		goto out;
+	}
+
+	/* Not having any binding is ok */
+	if (n < 1) {
+		ret = USBG_SUCCESS;
+		free(dent);
+		goto out;
+	}
+
+	/*
+	 * Only one configuration can be bound to os_descx, n should
+	 * equal 1.
+	 */
+	nmb = snprintf(&(bpath[end]), sizeof(bpath) - end,
+			"/%s", dent[0]->d_name);
+
+	for (i = 0; i < n; i++)
+		free(dent[i]);
+	free(dent);
+
+	if (nmb >= sizeof(bpath) - end) {
+		ret = USBG_ERROR_PATH_TOO_LONG;
+		goto out;
+	}
+
+	nmb = readlink(bpath, target, sizeof(target) - 1 );
+	if (nmb < 0) {
+		ret = usbg_translate_error(errno);
+		goto out;
+	}
+
+	/* readlink() don't add this, so we have to do it manually */
+	target[nmb] = '\0';
+	/* Target contains a full path but we only need function dir name */
+	target_name = strrchr(target, '/') + 1;
+	id = usbg_split_config_label_id(target_name, &label);
+	if (id <= 0) {
+		ret = id;
+		goto out;
+	}
+
+	c = usbg_get_config(g, id, label);
+	if (!c) {
+		ret = USBG_ERROR_NO_MEM;
+		goto out;
+	}
+
+	g->os_desc_binding = c;
+
+out:
+	return ret;
+}
+
+
 static int usbg_parse_config(const char *path, const char *name,
 		usbg_gadget *g)
 {
@@ -871,6 +949,10 @@ static inline int usbg_parse_gadget(usbg_gadget *g)
 		goto out;
 
 	ret = usbg_parse_configs(g->path, g);
+	if (ret != USBG_SUCCESS)
+		goto out;
+
+	ret = usbg_parse_gadget_os_desc_binding(g);
 out:
 	return ret;
 }
@@ -1150,6 +1232,11 @@ out:
 	return ret;
 }
 
+usbg_config *usbg_get_os_desc_binding(usbg_gadget *g)
+{
+	return g->os_desc_binding;
+}
+
 int usbg_rm_config(usbg_config *c, int opts)
 {
 	int ret = USBG_ERROR_INVALID_PARAM;
@@ -2353,6 +2440,95 @@ int usbg_get_binding_name_s(usbg_binding *b, char *buf, int len)
 	return snprintf(buf, len, "%s", b->name);
 }
 
+static int usbg_create_os_desc_link(usbg_gadget *g, usbg_config *c)
+{
+	char bpath[USBG_MAX_PATH_LENGTH];
+	char cpath[USBG_MAX_PATH_LENGTH];
+	int nmb;
+	int ret;
+
+	nmb = snprintf(cpath, sizeof(cpath), "%s/%s", c->path, c->name);
+	if (nmb >= sizeof(cpath)) {
+		ret = USBG_ERROR_PATH_TOO_LONG;
+		goto out;
+	}
+
+	nmb = snprintf(bpath, sizeof(bpath), "%s/%s/%s/%s", g->path, g->name,
+			OS_DESC_DIR, c->name);
+	if (nmb >= sizeof(bpath)) {
+		ret = USBG_ERROR_PATH_TOO_LONG;
+		goto out;
+	}
+
+	ret = symlink(cpath, bpath);
+	if (ret != 0) {
+		ret = usbg_translate_error(errno);
+		goto out;
+	}
+
+	g->os_desc_binding = c;
+
+	return USBG_SUCCESS;
+out:
+	return ret;
+}
+
+static int usbg_rm_os_desc_link(usbg_gadget *g)
+{
+	char bpath[USBG_MAX_PATH_LENGTH];
+	struct dirent **dent;
+	int end, n, i;
+	int ret;
+
+	end = snprintf(bpath, sizeof(bpath), "%s/%s/%s", g->path, g->name,
+		       OS_DESC_DIR);
+	if (end >= sizeof(bpath)) {
+		ret = USBG_ERROR_PATH_TOO_LONG;
+		goto out;
+	}
+
+	n = scandir(bpath, &dent, bindings_select, alphasort);
+	if (n < 0) {
+		ret = usbg_translate_error(errno);
+		goto out;
+	}
+
+	if (n < 1) {
+		ret = USBG_ERROR_NOT_FOUND;
+		goto free_dent;
+	}
+
+	ret = ubsg_rm_file(bpath, dent[0]->d_name);
+
+	for (i = 0; i < n; i++)
+		free(dent[i]);
+free_dent:
+	free(dent);
+out:
+	return ret;
+}
+
+int usbg_set_os_desc_config(usbg_gadget *g, usbg_config *c)
+{
+	int ret;
+
+	if (!g)
+		return USBG_ERROR_INVALID_PARAM;
+
+	if (c) {
+		if (g->os_desc_binding) {
+			ERROR("os desc binding exist\n");
+			return USBG_ERROR_EXIST;
+		}
+
+		ret = usbg_create_os_desc_link(g, c);
+	} else {
+		ret = usbg_rm_os_desc_link(g);
+	}
+
+	return ret;
+}
+
 int usbg_enable_gadget(usbg_gadget *g, usbg_udc *udc)
 {
 	int ret = USBG_ERROR_INVALID_PARAM;
diff --git a/src/usbg_schemes_libconfig.c b/src/usbg_schemes_libconfig.c
index c24b449..22e405f 100644
--- a/src/usbg_schemes_libconfig.c
+++ b/src/usbg_schemes_libconfig.c
@@ -29,6 +29,7 @@
 #define USBG_ID_TAG "id"
 #define USBG_FUNCTION_TAG "function"
 #define USBG_INTERFACE_TAG "interface"
+#define USBG_CONFIG_ID_TAG "config_id"
 #define USBG_TAB_WIDTH 4
 
 static inline int generate_function_label(usbg_function *f, char *buf, int size)
@@ -593,6 +594,19 @@ static int usbg_export_gadget_os_descs(usbg_gadget *g, config_setting_t *root)
 	int usbg_ret, cfg_ret;
 	int ret = USBG_ERROR_NO_MEM;
 
+	if (g->os_desc_binding) {
+		node = config_setting_add(root, USBG_CONFIG_ID_TAG,
+					  CONFIG_TYPE_INT);
+		if (!node)
+			goto out;
+
+		cfg_ret = config_setting_set_int(node, g->os_desc_binding->id);
+		if (cfg_ret != CONFIG_TRUE) {
+			ret = USBG_ERROR_OTHER_ERROR;
+			goto out;
+		}
+	}
+
 	usbg_ret = usbg_get_gadget_os_descs(g, &g_os_descs);
 	if (usbg_ret) {
 		ret = usbg_ret;
@@ -1578,6 +1592,28 @@ static int usbg_import_gadget_os_descs(config_setting_t *root, usbg_gadget *g)
 
 	ret = usbg_set_gadget_os_descs(g, &g_os_descs);
 
+	/*
+	 * Configs are optional, because some config may not be
+	 * fully configured and not contain any config yet
+	 */
+	node = config_setting_get_member(root, USBG_CONFIG_ID_TAG);
+	if (node) {
+		usbg_config *target;
+		if (!usbg_config_is_int(node))
+			goto out;
+
+		val = config_setting_get_int(node);
+		target = usbg_get_config(g, val, NULL);
+		if (!target) {
+			ret = USBG_ERROR_NOT_FOUND;
+			goto out;
+		}
+
+		usbg_ret = usbg_set_os_desc_config(g, target);
+		if (usbg_ret != USBG_SUCCESS)
+			goto out;
+	}
+
 out:
 	return ret;
 }