xref: /linux/lib/bootconfig.c (revision e84e60da22ea2fb48576d8d78def44fab677374e)

// SPDX-License-Identifier: GPL-2.0
/*
 * Extra Boot Config
 * Masami Hiramatsu <mhiramat@kernel.org>
 */

/*
 * NOTE: This is only for tools/bootconfig, because tools/bootconfig will
 * run the parser sanity test.
 * This does NOT mean lib/bootconfig.c is available in the user space.
 * However, if you change this file, please make sure the tools/bootconfig
 * has no issue on building and running.
 */
#include <linux/bootconfig.h>

#ifdef __KERNEL__
#include <linux/bug.h>
#include <linux/ctype.h>
#include <linux/errno.h>
#include <linux/cache.h>
#include <linux/compiler.h>
#include <linux/init.h>
#include <linux/moduleparam.h>
#include <linux/printk.h>
#include <linux/sprintf.h>
#include <linux/memblock.h>
#include <linux/string.h>
#include <asm/setup.h>		/* COMMAND_LINE_SIZE */

#ifdef CONFIG_BOOT_CONFIG_EMBED
/* embedded_bootconfig_data is defined in bootconfig-data.S */
extern __visible const char embedded_bootconfig_data[];
extern __visible const char embedded_bootconfig_data_end[];

const char * __init xbc_get_embedded_bootconfig(size_t *size)
{
	*size = embedded_bootconfig_data_end - embedded_bootconfig_data;
	return (*size) ? embedded_bootconfig_data : NULL;
}
#endif

#ifdef CONFIG_CMDLINE_FROM_BOOTCONFIG
/* embedded_kernel_cmdline is defined in embedded-cmdline.S */
extern __visible const char embedded_kernel_cmdline[];
extern __visible const char embedded_kernel_cmdline_end[];

/* Set once the embedded cmdline has actually been prepended. */
static bool xbc_cmdline_applied __initdata;

/*
 * str_prepend() - Prepend @src in front of the string in @dst, in place
 * @dst: NUL-terminated destination buffer, currently @dst_len bytes long
 * @dst_len: length of the current @dst string (excluding its NUL)
 * @src: bytes to prepend (not NUL-terminated)
 * @src_len: number of bytes from @src to prepend
 *
 * The caller must guarantee @dst has room for src_len + dst_len + 1 bytes.
 * Moving dst_len + 1 bytes carries @dst's NUL terminator too, so an empty
 * @dst needs no special case.
 */
static void __init str_prepend(char *dst, size_t dst_len,
			       const char *src, size_t src_len)
{
	memmove(dst + src_len, dst, dst_len + 1);
	memcpy(dst, src, src_len);
}

/**
 * xbc_prepend_embedded_cmdline() - Prepend embedded bootconfig cmdline
 * @dst: cmdline buffer to prepend into (must already contain a NUL byte)
 * @size: total capacity of @dst in bytes
 *
 * Prepend the build-time-rendered "kernel" subtree of the embedded
 * bootconfig to @dst. The rendered string already ends with a single
 * space (the xbc_snprint_cmdline() invariant), which serves as the
 * separator between the embedded keys and any existing content of @dst.
 * On overflow, log an error and leave @dst untouched rather than
 * silently truncating: booting without the embedded values is better
 * than refusing to boot, and the error message tells the user why
 * their embedded keys are missing.
 *
 * Intended to be called from setup_arch() before parse_early_param() so
 * that early_param() handlers see the embedded values.
 */
void __init xbc_prepend_embedded_cmdline(char *dst, size_t size)
{
	size_t embed_len = embedded_kernel_cmdline_end - embedded_kernel_cmdline;
	size_t dst_len;

	if (!size || embed_len <= 1)	/* trailing NUL only */
		return;
	embed_len--;			/* exclude trailing NUL byte */

	dst_len = strnlen(dst, size);
	if (embed_len + dst_len + 1 > size) {
		pr_err("embedded bootconfig cmdline (%zu bytes) does not fit in COMMAND_LINE_SIZE with %zu bytes already used; ignoring embedded values\n",
		       embed_len, dst_len);
		return;
	}

	str_prepend(dst, dst_len, embedded_kernel_cmdline, embed_len);
	xbc_cmdline_applied = true;
}

/**
 * xbc_embedded_cmdline_applied() - Did the embedded cmdline get prepended?
 *
 * Return true if xbc_prepend_embedded_cmdline() actually prepended the
 * embedded "kernel" subtree. setup_boot_config() uses this to avoid
 * rendering the same keys a second time.
 */
bool __init xbc_embedded_cmdline_applied(void)
{
	return xbc_cmdline_applied;
}
#endif	/* CONFIG_CMDLINE_FROM_BOOTCONFIG */

/* parse_args() callback: flag when the "bootconfig" parameter is present. */
static int __init bootconfig_optin(char *param, char *val,
				   const char *unused, void *arg)
{
	if (!strcmp(param, "bootconfig"))
		*(bool *)arg = true;
	return 0;
}

/**
 * bootconfig_cmdline_requested() - Was "bootconfig" passed on the cmdline?
 * @boot_cmdline: kernel command line to inspect (not modified)
 * @end_offset: if non-NULL, set to the offset of the init arguments that
 *		follow a "--" separator, or 0 when there is none
 *
 * Parse a private copy of @boot_cmdline (parse_args() is destructive) and
 * report whether "bootconfig" is present before the "--" separator.
 * setup_arch() uses this to gate prepending the build-time embedded cmdline;
 * setup_boot_config() uses it for the runtime opt-in and to locate the init
 * arguments via @end_offset. Sharing one parser keeps the early and late
 * paths agreeing on what counts as opt-in. CONFIG_BOOT_CONFIG_FORCE is not
 * folded in here; callers apply it where they need it.
 */
bool __init bootconfig_cmdline_requested(const char *boot_cmdline, int *end_offset)
{
	static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata;
	bool found = false;
	char *err;

	if (end_offset)
		*end_offset = 0;

	strscpy(tmp_cmdline, boot_cmdline, COMMAND_LINE_SIZE);
	err = parse_args("bootconfig", tmp_cmdline, NULL, 0, 0, 0,
			 &found, bootconfig_optin);
	if (IS_ERR(err))
		return false;

	/* parse_args() stops at "--" and returns the address of the rest. */
	if (end_offset && err)
		*end_offset = err - tmp_cmdline;

	return found;
}

#endif	/* __KERNEL__ */

/*
 * Extra Boot Config (XBC) is given as tree-structured ascii text of
 * key-value pairs on memory.
 * xbc_parse() parses the text to build a simple tree. Each tree node is
 * simply a key word or a value. A key node may have a next key node or/and
 * a child node (both key and value). A value node may have a next value
 * node (for array).
 */

static struct xbc_node *xbc_nodes __initdata;
static int xbc_node_num __initdata;
static char *xbc_data __initdata;
static size_t xbc_data_size __initdata;
static struct xbc_node *last_parent __initdata;
static const char *xbc_err_msg __initdata;
static int xbc_err_pos __initdata;
static int open_brace[XBC_DEPTH_MAX] __initdata;
static int brace_index __initdata;

#ifdef __KERNEL__
static inline void * __init xbc_alloc_mem(size_t size)
{
	return memblock_alloc(size, SMP_CACHE_BYTES);
}

static inline void __init xbc_free_mem(void *addr, size_t size)
{
	memblock_free(addr, size);
}

#else /* !__KERNEL__ */

static inline void *xbc_alloc_mem(size_t size)
{
	return calloc(1, size);
}

static inline void xbc_free_mem(void *addr, size_t size)
{
	free(addr);
}
#endif

/**
 * xbc_get_info() - Get the information of loaded boot config
 * @node_size: A pointer to store the number of nodes.
 * @data_size: A pointer to store the size of bootconfig data.
 *
 * Get the number of used nodes in @node_size if it is not NULL,
 * and the size of bootconfig data in @data_size if it is not NULL.
 * Return 0 if the boot config is initialized, or return -ENODEV.
 */
int __init xbc_get_info(int *node_size, size_t *data_size)
{
	if (!xbc_data)
		return -ENODEV;

	if (node_size)
		*node_size = xbc_node_num;
	if (data_size)
		*data_size = xbc_data_size;
	return 0;
}

static int __init xbc_parse_error(const char *msg, const char *p)
{
	xbc_err_msg = msg;
	xbc_err_pos = (int)(p - xbc_data);

	return -EINVAL;
}

/**
 * xbc_root_node() - Get the root node of extended boot config
 *
 * Return the address of root node of extended boot config. If the
 * extended boot config is not initialized, return NULL.
 */
struct xbc_node * __init xbc_root_node(void)
{
	if (unlikely(!xbc_data))
		return NULL;

	return xbc_nodes;
}

/**
 * xbc_node_index() - Get the index of XBC node
 * @node: A target node of getting index.
 *
 * Return the index number of @node in XBC node list.
 */
uint16_t __init xbc_node_index(struct xbc_node *node)
{
	return (uint16_t)(node - &xbc_nodes[0]);
}

/**
 * xbc_node_get_parent() - Get the parent XBC node
 * @node: An XBC node.
 *
 * Return the parent node of @node. If the node is top node of the tree,
 * return NULL.
 */
struct xbc_node * __init xbc_node_get_parent(struct xbc_node *node)
{
	return node->parent == XBC_NODE_MAX ? NULL : &xbc_nodes[node->parent];
}

/**
 * xbc_node_get_child() - Get the child XBC node
 * @node: An XBC node.
 *
 * Return the first child node of @node. If the node has no child, return
 * NULL.
 */
struct xbc_node * __init xbc_node_get_child(struct xbc_node *node)
{
	return node->child ? &xbc_nodes[node->child] : NULL;
}

/**
 * xbc_node_get_next() - Get the next sibling XBC node
 * @node: An XBC node.
 *
 * Return the NEXT sibling node of @node. If the node has no next sibling,
 * return NULL. Note that even if this returns NULL, it doesn't mean @node
 * has no siblings. (You also has to check whether the parent's child node
 * is @node or not.)
 */
struct xbc_node * __init xbc_node_get_next(struct xbc_node *node)
{
	return node->next ? &xbc_nodes[node->next] : NULL;
}

/**
 * xbc_node_get_data() - Get the data of XBC node
 * @node: An XBC node.
 *
 * Return the data (which is always a null terminated string) of @node.
 * If the node has invalid data, warn and return NULL.
 */
const char * __init xbc_node_get_data(struct xbc_node *node)
{
	size_t offset = node->data & ~XBC_VALUE;

	if (WARN_ON(offset >= xbc_data_size))
		return NULL;

	return xbc_data + offset;
}

static bool __init
xbc_node_match_prefix(struct xbc_node *node, const char **prefix)
{
	const char *p = xbc_node_get_data(node);
	size_t len = strlen(p);

	if (strncmp(*prefix, p, len))
		return false;

	p = *prefix + len;
	if (*p == '.')
		p++;
	else if (*p != '\0')
		return false;
	*prefix = p;

	return true;
}

/**
 * xbc_node_find_subkey() - Find a subkey node which matches given key
 * @parent: An XBC node.
 * @key: A key string.
 *
 * Search a key node under @parent which matches @key. The @key can contain
 * several words jointed with '.'. If @parent is NULL, this searches the
 * node from whole tree. Return NULL if no node is matched.
 */
struct xbc_node * __init
xbc_node_find_subkey(struct xbc_node *parent, const char *key)
{
	struct xbc_node *node;

	if (parent)
		node = xbc_node_get_subkey(parent);
	else
		node = xbc_root_node();

	while (node && xbc_node_is_key(node)) {
		if (!xbc_node_match_prefix(node, &key))
			node = xbc_node_get_next(node);
		else if (*key != '\0')
			node = xbc_node_get_subkey(node);
		else
			break;
	}

	return node;
}

/**
 * xbc_node_find_value() - Find a value node which matches given key
 * @parent: An XBC node.
 * @key: A key string.
 * @vnode: A container pointer of found XBC node.
 *
 * Search a value node under @parent whose (parent) key node matches @key,
 * store it in *@vnode, and returns the value string.
 * The @key can contain several words jointed with '.'. If @parent is NULL,
 * this searches the node from whole tree. Return the value string if a
 * matched key found, return NULL if no node is matched.
 * Note that this returns 0-length string and stores NULL in *@vnode if the
 * key has no value. And also it will return the value of the first entry if
 * the value is an array.
 */
const char * __init
xbc_node_find_value(struct xbc_node *parent, const char *key,
		    struct xbc_node **vnode)
{
	struct xbc_node *node = xbc_node_find_subkey(parent, key);

	if (!node || !xbc_node_is_key(node))
		return NULL;

	node = xbc_node_get_child(node);
	if (node && !xbc_node_is_value(node))
		return NULL;

	if (vnode)
		*vnode = node;

	return node ? xbc_node_get_data(node) : "";
}

/**
 * xbc_node_compose_key_after() - Compose partial key string of the XBC node
 * @root: Root XBC node
 * @node: Target XBC node.
 * @buf: A buffer to store the key.
 * @size: The size of the @buf.
 *
 * Compose the partial key of the @node into @buf, which is starting right
 * after @root (@root is not included.) If @root is NULL, this returns full
 * key words of @node.
 * Returns the total length of the key stored in @buf. Returns -EINVAL
 * if @node is NULL or @root is not the ancestor of @node or @root is @node,
 * or returns -ERANGE if the key depth is deeper than max depth.
 * This is expected to be used with xbc_find_node() to list up all (child)
 * keys under given key.
 */
int __init xbc_node_compose_key_after(struct xbc_node *root,
				      struct xbc_node *node,
				      char *buf, size_t size)
{
	uint16_t keys[XBC_DEPTH_MAX];
	int depth = 0, ret = 0, total = 0;

	if (!node || node == root)
		return -EINVAL;

	if (xbc_node_is_value(node))
		node = xbc_node_get_parent(node);

	while (node && node != root) {
		keys[depth++] = xbc_node_index(node);
		if (depth == XBC_DEPTH_MAX)
			return -ERANGE;
		node = xbc_node_get_parent(node);
	}
	if (!node && root)
		return -EINVAL;

	while (--depth >= 0) {
		node = xbc_nodes + keys[depth];
		ret = snprintf(buf, size, "%s%s", xbc_node_get_data(node),
			       depth ? "." : "");
		if (ret < 0)
			return ret;
		if (ret >= size) {
			size = 0;
		} else {
			size -= ret;
			buf += ret;
		}
		total += ret;
	}

	return total;
}

/**
 * xbc_node_find_next_leaf() - Find the next leaf node under given node
 * @root: An XBC root node
 * @node: An XBC node which starts from.
 *
 * Search the next leaf node (which means the terminal key node) of @node
 * under @root node (including @root node itself).
 * Return the next node or NULL if next leaf node is not found.
 */
struct xbc_node * __init xbc_node_find_next_leaf(struct xbc_node *root,
						 struct xbc_node *node)
{
	struct xbc_node *next;

	if (unlikely(!xbc_data))
		return NULL;

	if (!node) {	/* First try */
		node = root;
		if (!node)
			node = xbc_nodes;
	} else {
		/* Leaf node may have a subkey */
		next = xbc_node_get_subkey(node);
		if (next) {
			node = next;
			goto found;
		}

		if (node == root)	/* @root was a leaf, no child node. */
			return NULL;

		while (!node->next) {
			node = xbc_node_get_parent(node);
			if (node == root)
				return NULL;
			/* User passed a node which is not under parent */
			if (WARN_ON(!node))
				return NULL;
		}
		node = xbc_node_get_next(node);
	}

found:
	while (node && !xbc_node_is_leaf(node))
		node = xbc_node_get_child(node);

	return node;
}

/**
 * xbc_node_find_next_key_value() - Find the next key-value pair nodes
 * @root: An XBC root node
 * @leaf: A container pointer of XBC node which starts from.
 *
 * Search the next leaf node (which means the terminal key node) of *@leaf
 * under @root node. Returns the value and update *@leaf if next leaf node
 * is found, or NULL if no next leaf node is found.
 * Note that this returns 0-length string if the key has no value, or
 * the value of the first entry if the value is an array.
 */
const char * __init xbc_node_find_next_key_value(struct xbc_node *root,
						 struct xbc_node **leaf)
{
	/* tip must be passed */
	if (WARN_ON(!leaf))
		return NULL;

	*leaf = xbc_node_find_next_leaf(root, *leaf);
	if (!*leaf)
		return NULL;
	if ((*leaf)->child)
		return xbc_node_get_data(xbc_node_get_child(*leaf));
	else
		return "";	/* No value key */
}

static char xbc_namebuf[XBC_KEYLEN_MAX] __initdata;

#define rest(dst, end) ((end) > (dst) ? (end) - (dst) : 0)

/**
 * xbc_snprint_cmdline_filter() - Render bootconfig keys as cmdline string
 * @buf: Destination buffer (may be NULL when @size is 0 to query the length)
 * @size: Size of @buf in bytes
 * @root: Subtree root whose key=value pairs should be rendered
 * @filter: Filter callback (returns true to include, false to skip; may be NULL)
 * @data: Private context passed to @filter
 *
 * Walk all key/value pairs under @root and emit them as a space-separated
 * cmdline string into @buf. Values containing whitespace are quoted with
 * double quotes. Keys for which @filter returns false are omitted.
 * Returns the number of bytes that would be written if @buf were large enough
 * (matching snprintf semantics), or a negative errno on failure.
 */
int __init xbc_snprint_cmdline_filter(char *buf, size_t size, struct xbc_node *root,
				      xbc_cmdline_filter_fn filter, void *data)
{
	struct xbc_node *knode, *vnode;
	const char *val, *q;
	size_t len = 0;
	int ret;

	/*
	 * Track the running written length rather than advancing @buf, so we
	 * never form "buf + size" or "buf += ret" while @buf is NULL (the
	 * size-probe call passes buf=NULL, size=0). NULL pointer arithmetic
	 * is undefined behavior and trips host UBSan / FORTIFY_SOURCE when
	 * this renderer runs at kernel build time. snprintf(NULL, 0, ...)
	 * itself is well defined and returns the would-be length.
	 */
	xbc_node_for_each_key_value(root, knode, val) {
		/*
		 * An empty or value-only @root (e.g. "kernel {}" or
		 * "kernel = x", possibly alongside "kernel.foo = bar")
		 * yields @root itself here. Skip it: composing a key for it
		 * would fail with -EINVAL, yet any real descendant keys must
		 * still be rendered. An entirely empty subtree then renders
		 * nothing and returns 0 rather than an error.
		 */
		if (knode == root)
			continue;

		ret = xbc_node_compose_key_after(root, knode,
					xbc_namebuf, XBC_KEYLEN_MAX);
		if (ret < 0)
			return ret;

		if (filter && !filter(knode, xbc_namebuf, data))
			continue;

		vnode = xbc_node_get_child(knode);
		if (!vnode) {
			ret = snprintf(buf ? buf + len : NULL, rest(len, size),
				       "%s ", xbc_namebuf);
			if (ret < 0)
				return ret;
			len += ret;
			continue;
		}
		xbc_array_for_each_value(vnode, val) {
			/*
			 * For prettier and more readable /proc/cmdline, only
			 * quote the value when necessary, i.e. when it contains
			 * whitespace.
			 */
			q = strpbrk(val, " \t\r\n") ? "\"" : "";
			ret = snprintf(buf ? buf + len : NULL, rest(len, size),
				       "%s=%s%s%s ", xbc_namebuf, q, val, q);
			if (ret < 0)
				return ret;
			len += ret;
		}
	}

	return len;
}
#undef rest

/* XBC parse and tree build */

static int __init xbc_init_node(struct xbc_node *node, char *data, uint16_t flag)
{
	long offset = data - xbc_data;

	if (WARN_ON(offset < 0 || offset >= XBC_DATA_MAX))
		return -EINVAL;

	node->data = (uint16_t)offset | flag;
	node->child = 0;
	node->next = 0;

	return 0;
}

static struct xbc_node * __init xbc_add_node(char *data, uint16_t flag)
{
	struct xbc_node *node;

	if (xbc_node_num == XBC_NODE_MAX)
		return NULL;

	node = &xbc_nodes[xbc_node_num];
	if (xbc_init_node(node, data, flag) < 0)
		return NULL;
	xbc_node_num++;

	return node;
}

static inline __init struct xbc_node *xbc_last_sibling(struct xbc_node *node)
{
	while (node->next)
		node = xbc_node_get_next(node);

	return node;
}

static inline __init struct xbc_node *xbc_last_child(struct xbc_node *node)
{
	while (node->child)
		node = xbc_node_get_child(node);

	return node;
}

static struct xbc_node * __init __xbc_add_sibling(char *data, uint16_t flag, bool head)
{
	struct xbc_node *sib, *node = xbc_add_node(data, flag);

	if (node) {
		if (!last_parent) {
			/* Ignore @head in this case */
			node->parent = XBC_NODE_MAX;
			sib = xbc_last_sibling(xbc_nodes);
			sib->next = xbc_node_index(node);
		} else {
			node->parent = xbc_node_index(last_parent);
			if (!last_parent->child || head) {
				node->next = last_parent->child;
				last_parent->child = xbc_node_index(node);
			} else {
				sib = xbc_node_get_child(last_parent);
				sib = xbc_last_sibling(sib);
				sib->next = xbc_node_index(node);
			}
		}
	} else {
		xbc_parse_error("Too many nodes", data);
	}

	return node;
}

static inline struct xbc_node * __init xbc_add_sibling(char *data, uint16_t flag)
{
	return __xbc_add_sibling(data, flag, false);
}

static inline struct xbc_node * __init xbc_add_head_sibling(char *data, uint16_t flag)
{
	return __xbc_add_sibling(data, flag, true);
}

static inline __init struct xbc_node *xbc_add_child(char *data, uint16_t flag)
{
	struct xbc_node *node = xbc_add_sibling(data, flag);

	if (node)
		last_parent = node;

	return node;
}

static inline __init bool xbc_valid_keyword(char *key)
{
	if (key[0] == '\0')
		return false;

	while (isalnum(*key) || *key == '-' || *key == '_')
		key++;

	return *key == '\0';
}

static char *skip_comment(char *p)
{
	char *ret;

	ret = strchr(p, '\n');
	if (!ret)
		ret = p + strlen(p);
	else
		ret++;

	return ret;
}

static char *skip_spaces_until_newline(char *p)
{
	while (isspace(*p) && *p != '\n')
		p++;
	return p;
}

static int __init __xbc_open_brace(char *p)
{
	/* Push the last key as open brace */
	if (brace_index >= XBC_DEPTH_MAX)
		return xbc_parse_error("Exceed max depth of braces", p);
	open_brace[brace_index++] = xbc_node_index(last_parent);

	return 0;
}

static int __init __xbc_close_brace(char *p)
{
	brace_index--;
	if (!last_parent || brace_index < 0 ||
	    (open_brace[brace_index] != xbc_node_index(last_parent)))
		return xbc_parse_error("Unexpected closing brace", p);

	if (brace_index == 0)
		last_parent = NULL;
	else
		last_parent = &xbc_nodes[open_brace[brace_index - 1]];

	return 0;
}

/*
 * Return delimiter or error, no node added. As same as lib/cmdline.c,
 * you can use " around spaces, but can't escape " for value.
 * *@__v must point real value string. (not including spaces before value.)
 */
static int __init __xbc_parse_value(char **__v, char **__n)
{
	char *p, *v = *__v;
	int c, quotes = 0;

	if (*v == '"' || *v == '\'') {
		quotes = *v;
		v++;
	}
	p = v - 1;
	while ((c = *++p)) {
		if (!isprint(c) && !isspace(c))
			return xbc_parse_error("Non printable value", p);
		if (quotes) {
			if (c != quotes)
				continue;
			quotes = 0;
			*p++ = '\0';
			p = skip_spaces_until_newline(p);
			c = *p;
			if (c && !strchr(",;\n#}", c))
				return xbc_parse_error("No value delimiter", p);
			if (*p)
				p++;
			break;
		}
		if (strchr(",;\n#}", c)) {
			*p++ = '\0';
			v = strim(v);
			break;
		}
	}
	if (quotes)
		return xbc_parse_error("No closing quotes", p);
	if (c == '#') {
		p = skip_comment(p);
		c = '\n';	/* A comment must be treated as a newline */
	}
	*__n = p;
	*__v = v;

	return c;
}

static int __init xbc_parse_array(char **__v)
{
	struct xbc_node *node;
	char *next;
	int c = 0;

	if (last_parent->child)
		last_parent = xbc_node_get_child(last_parent);

	do {
		/* Search the next array value beyond comments and empty lines */
		next = skip_spaces(*__v);
		while (*next == '#') {
			next = skip_comment(next);
			next = skip_spaces(next);
		}
		*__v = next;
		c = __xbc_parse_value(__v, &next);
		if (c < 0)
			return c;

		node = xbc_add_child(*__v, XBC_VALUE);
		if (!node)
			return -ENOMEM;
		*__v = next;
	} while (c == ',');

	return c;
}

static inline __init
struct xbc_node *find_match_node(struct xbc_node *node, char *k)
{
	while (node) {
		if (!strcmp(xbc_node_get_data(node), k))
			break;
		node = xbc_node_get_next(node);
	}
	return node;
}

static int __init __xbc_add_key(char *k)
{
	struct xbc_node *node, *child;

	if (!xbc_valid_keyword(k))
		return xbc_parse_error("Invalid keyword", k);

	if (unlikely(xbc_node_num == 0))
		goto add_node;

	if (!last_parent) {	/* the first level */
		node = find_match_node(xbc_nodes, k);
	} else {
		child = xbc_node_get_child(last_parent);
		/* Since the value node is the first child, skip it. */
		if (child && xbc_node_is_value(child))
			child = xbc_node_get_next(child);
		node = find_match_node(child, k);
	}

	if (node) {
		last_parent = node;
	} else {
add_node:
		node = xbc_add_child(k, XBC_KEY);
		if (!node)
			return -ENOMEM;
	}
	return 0;
}

static int __init __xbc_parse_keys(char *k)
{
	char *p;
	int ret;

	k = strim(k);
	while ((p = strchr(k, '.'))) {
		*p++ = '\0';
		ret = __xbc_add_key(k);
		if (ret)
			return ret;
		k = p;
	}

	return __xbc_add_key(k);
}

static int __init xbc_parse_kv(char **k, char *v, int op)
{
	struct xbc_node *prev_parent = last_parent;
	struct xbc_node *child;
	char *next;
	int c, ret;

	ret = __xbc_parse_keys(*k);
	if (ret)
		return ret;

	v = skip_spaces_until_newline(v);
	/* If there is a comment, this has an empty value. */
	if (*v == '#') {
		next = skip_comment(v);
		*v = '\0';
		c = '\n';
	} else {
		c = __xbc_parse_value(&v, &next);
		if (c < 0)
			return c;
	}

	child = xbc_node_get_child(last_parent);
	if (child && xbc_node_is_value(child)) {
		if (op == '=')
			return xbc_parse_error("Value is redefined", v);
		if (op == ':') {
			unsigned short nidx = child->next;

			if (xbc_init_node(child, v, XBC_VALUE) < 0)
				return xbc_parse_error("Failed to override value", v);
			child->next = nidx;	/* keep subkeys */
			goto array;
		}
		/* op must be '+' */
		last_parent = xbc_last_child(child);
	}
	/* The value node should always be the first child */
	if (!xbc_add_head_sibling(v, XBC_VALUE))
		return -ENOMEM;

array:
	if (c == ',') {	/* Array */
		c = xbc_parse_array(&next);
		if (c < 0)
			return c;
	}

	last_parent = prev_parent;

	if (c == '}') {
		ret = __xbc_close_brace(next - 1);
		if (ret < 0)
			return ret;
	}

	*k = next;

	return 0;
}

static int __init xbc_parse_key(char **k, char *n)
{
	struct xbc_node *prev_parent = last_parent;
	int ret;

	*k = strim(*k);
	if (**k != '\0') {
		ret = __xbc_parse_keys(*k);
		if (ret)
			return ret;
		last_parent = prev_parent;
	}
	*k = n;

	return 0;
}

static int __init xbc_open_brace(char **k, char *n)
{
	int ret;

	ret = __xbc_parse_keys(*k);
	if (ret)
		return ret;
	*k = n;

	return __xbc_open_brace(n - 1);
}

static int __init xbc_close_brace(char **k, char *n)
{
	int ret;

	ret = xbc_parse_key(k, n);
	if (ret)
		return ret;
	/* k is updated in xbc_parse_key() */

	return __xbc_close_brace(n - 1);
}

#ifndef __KERNEL__
/* Sanity check for regression: node indices must be within bounds */
static int __init xbc_sanity_check_tree(void)
{
	int i;

	for (i = 0; i < xbc_node_num; i++) {
		if (xbc_nodes[i].next >= xbc_node_num) {
			return xbc_parse_error("No closing brace",
				xbc_node_get_data(xbc_nodes + i));
		}
		if (xbc_nodes[i].child >= xbc_node_num) {
			return xbc_parse_error("Broken child node",
				xbc_node_get_data(xbc_nodes + i));
		}
	}

	return 0;
}
#endif

static int __init xbc_verify_tree(void)
{
	int depth;
	size_t len, wlen;
	struct xbc_node *n, *m;

	/* Brace closing */
	if (brace_index) {
		n = &xbc_nodes[open_brace[brace_index - 1]];
		return xbc_parse_error("Brace is not closed",
					xbc_node_get_data(n));
	}

	/* Empty tree */
	if (xbc_node_num == 0) {
		xbc_parse_error("Empty config", xbc_data);
		return -ENOENT;
	}

	/* Key tree limitation check */
	n = &xbc_nodes[0];
	depth = 1;
	len = 0;

	while (n) {
		wlen = strlen(xbc_node_get_data(n)) + 1;
		len += wlen;
		if (len > XBC_KEYLEN_MAX)
			return xbc_parse_error("Too long key length",
				xbc_node_get_data(n));

		m = xbc_node_get_child(n);
		if (m && xbc_node_is_key(m)) {
			n = m;
			depth++;
			if (depth > XBC_DEPTH_MAX)
				return xbc_parse_error("Too many key words",
						xbc_node_get_data(n));
			continue;
		}
		len -= wlen;
		m = xbc_node_get_next(n);
		while (!m) {
			n = xbc_node_get_parent(n);
			if (!n)
				break;
			len -= strlen(xbc_node_get_data(n)) + 1;
			depth--;
			m = xbc_node_get_next(n);
		}
		n = m;
	}

	return 0;
}

/* Need to setup xbc_data and xbc_nodes before call this. */
static int __init xbc_parse_tree(void)
{
	char *p, *q;
	int ret = 0, c;

	last_parent = NULL;
	p = xbc_data;
	do {
		q = strpbrk(p, "{}=+;:\n#");
		if (!q) {
			p = skip_spaces(p);
			if (*p != '\0')
				ret = xbc_parse_error("No delimiter", p);
			break;
		}

		c = *q;
		*q++ = '\0';
		switch (c) {
		case ':':
		case '+':
			if (*q++ != '=') {
				ret = xbc_parse_error(c == '+' ?
						"Wrong '+' operator" :
						"Wrong ':' operator",
							q - 2);
				break;
			}
			fallthrough;
		case '=':
			ret = xbc_parse_kv(&p, q, c);
			break;
		case '{':
			ret = xbc_open_brace(&p, q);
			break;
		case '#':
			q = skip_comment(q);
			fallthrough;
		case ';':
		case '\n':
			ret = xbc_parse_key(&p, q);
			break;
		case '}':
			ret = xbc_close_brace(&p, q);
			break;
		}
	} while (!ret);

	if (!ret) {
		while (p < xbc_data + xbc_data_size - 1 && *p == '\0')
			p++;
		if (p < xbc_data + xbc_data_size - 1)
			ret = xbc_parse_error("Unexpected data after null character", p);
	}

	return ret;
}

/**
 * xbc_exit() - Clean up all parsed bootconfig
 *
 * This clears all data structures of parsed bootconfig on memory.
 * If you need to reuse xbc_init() with new boot config, you can
 * use this.
 */
void __init xbc_exit(void)
{
	xbc_free_mem(xbc_data, xbc_data_size);
	xbc_data = NULL;
	xbc_data_size = 0;
	xbc_node_num = 0;
	xbc_free_mem(xbc_nodes, sizeof(struct xbc_node) * XBC_NODE_MAX);
	xbc_nodes = NULL;
	brace_index = 0;
}

/**
 * xbc_init() - Parse given XBC file and build XBC internal tree
 * @data: The boot config text original data
 * @size: The size of @data
 * @emsg: A pointer of const char * to store the error message
 * @epos: A pointer of int to store the error position
 *
 * This parses the boot config text in @data. @size must be smaller
 * than XBC_DATA_MAX.
 * Return the number of stored nodes (>0) if succeeded, or -errno
 * if there is any error.
 * In error cases, @emsg will be updated with an error message and
 * @epos will be updated with the error position which is the byte offset
 * of @buf. If the error is not a parser error, @epos will be -1.
 */
int __init xbc_init(const char *data, size_t size, const char **emsg, int *epos)
{
	int ret;

	if (epos)
		*epos = -1;

	if (xbc_data) {
		if (emsg)
			*emsg = "Bootconfig is already initialized";
		return -EBUSY;
	}
	if (size > XBC_DATA_MAX || size == 0) {
		if (emsg)
			*emsg = size ? "Config data is too big" :
				"Config data is empty";
		return -ERANGE;
	}

	xbc_data = xbc_alloc_mem(size + 1);
	if (!xbc_data) {
		if (emsg)
			*emsg = "Failed to allocate bootconfig data";
		return -ENOMEM;
	}
	memcpy(xbc_data, data, size);
	xbc_data[size] = '\0';
	xbc_data_size = size + 1;

	xbc_nodes = xbc_alloc_mem(sizeof(struct xbc_node) * XBC_NODE_MAX);
	if (!xbc_nodes) {
		if (emsg)
			*emsg = "Failed to allocate bootconfig nodes";
		xbc_exit();
		return -ENOMEM;
	}

	ret = xbc_parse_tree();
	if (!ret)
		ret = xbc_verify_tree();
#ifndef __KERNEL__
	if (!ret)
		ret = xbc_sanity_check_tree();
#endif

	if (ret < 0) {
		if (epos)
			*epos = xbc_err_pos;
		if (emsg)
			*emsg = xbc_err_msg;
		xbc_exit();
	} else {
		ret = xbc_node_num;
	}

	return ret;
}