linux/drivers/greybus/manifest.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Greybus manifest parsing
 *
 * Copyright 2014-2015 Google Inc.
 * Copyright 2014-2015 Linaro Ltd.
 */

#include <linux/greybus.h>

static const char *get_descriptor_type_string(u8 type)
{ … }

/*
 * We scan the manifest once to identify where all the descriptors
 * are.  The result is a list of these manifest_desc structures.  We
 * then pick through them for what we're looking for (starting with
 * the interface descriptor).  As each is processed we remove it from
 * the list.  When we're done the list should (probably) be empty.
 */
struct manifest_desc { … };

static void release_manifest_descriptor(struct manifest_desc *descriptor)
{ … }

static void release_manifest_descriptors(struct gb_interface *intf)
{ … }

static void release_cport_descriptors(struct list_head *head, u8 bundle_id)
{ … }

static struct manifest_desc *get_next_bundle_desc(struct gb_interface *intf)
{ … }

/*
 * Validate the given descriptor.  Its reported size must fit within
 * the number of bytes remaining, and it must have a recognized
 * type.  Check that the reported size is at least as big as what
 * we expect to see.  (It could be bigger, perhaps for a new version
 * of the format.)
 *
 * Returns the (non-zero) number of bytes consumed by the descriptor,
 * or a negative errno.
 */
static int identify_descriptor(struct gb_interface *intf,
			       struct greybus_descriptor *desc, size_t size)
{ … }

/*
 * Find the string descriptor having the given id, validate it, and
 * allocate a duplicate copy of it.  The duplicate has an extra byte
 * which guarantees the returned string is NUL-terminated.
 *
 * String index 0 is valid (it represents "no string"), and for
 * that a null pointer is returned.
 *
 * Otherwise returns a pointer to a newly-allocated copy of the
 * descriptor string, or an error-coded pointer on failure.
 */
static char *gb_string_get(struct gb_interface *intf, u8 string_id)
{ … }

/*
 * Find cport descriptors in the manifest associated with the given
 * bundle, and set up data structures for the functions that use
 * them.  Returns the number of cports set up for the bundle, or 0
 * if there is an error.
 */
static u32 gb_manifest_parse_cports(struct gb_bundle *bundle)
{ … }

/*
 * Find bundle descriptors in the manifest and set up their data
 * structures.  Returns the number of bundles set up for the
 * given interface.
 */
static u32 gb_manifest_parse_bundles(struct gb_interface *intf)
{ … }

static bool gb_manifest_parse_interface(struct gb_interface *intf,
					struct manifest_desc *interface_desc)
{ … }

/*
 * Parse a buffer containing an interface manifest.
 *
 * If we find anything wrong with the content/format of the buffer
 * we reject it.
 *
 * The first requirement is that the manifest's version is
 * one we can parse.
 *
 * We make an initial pass through the buffer and identify all of
 * the descriptors it contains, keeping track for each its type
 * and the location size of its data in the buffer.
 *
 * Next we scan the descriptors, looking for an interface descriptor;
 * there must be exactly one of those.  When found, we record the
 * information it contains, and then remove that descriptor (and any
 * string descriptors it refers to) from further consideration.
 *
 * After that we look for the interface's bundles--there must be at
 * least one of those.
 *
 * Returns true if parsing was successful, false otherwise.
 */
bool gb_manifest_parse(struct gb_interface *intf, void *data, size_t size)
{ … }