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

#define pr_fmt(fmt)    "bootconfig: " fmt

#include <linux/bootconfig.h>
#include <linux/bug.h>
#include <linux/ctype.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/memblock.h>
#include <linux/printk.h>
#include <linux/string.h>

/*
 * 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;

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 initiized, 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.
 */
int __init xbc_node_index(struct xbc_node *node)
{
        return 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)
{
        int 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);
        int 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_child() - Find a child node which matches given key
 * @parent: An XBC node.
 * @key: A key string.
 *
 * Search a 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_child(struct xbc_node *parent, const char *key)
{
        struct xbc_node *node;

        if (parent)
                node = xbc_node_get_child(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_child(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_child(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)
{
        u16 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)
{
        if (unlikely(!xbc_data))
                return NULL;

        if (!node) {    /* First try */
                node = root;
                if (!node)
                        node = xbc_nodes;
        } else {
                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 uder parent */
                        if (WARN_ON(!node))
                                return NULL;
                }
                node = xbc_node_get_next(node);
        }

        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 */
}

/* XBC parse and tree build */

static int __init xbc_init_node(struct xbc_node *node, char *data, u32 flag)
{
        unsigned long offset = data - xbc_data;

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

        node->data = (u16)offset | flag;
        node->child = 0;
        node->next = 0;

        return 0;
}

static struct xbc_node * __init xbc_add_node(char *data, u32 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;

        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 struct xbc_node * __init xbc_add_sibling(char *data, u32 flag)
{
        struct xbc_node *sib, *node = xbc_add_node(data, flag);

        if (node) {
                if (!last_parent) {
                        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) {
                                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 __init struct xbc_node *xbc_add_child(char *data, u32 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 */
        open_brace[brace_index++] = xbc_node_index(last_parent);
        if (brace_index >= XBC_DEPTH_MAX)
                return xbc_parse_error("Exceed max depth of braces", p);

        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.
 */
static int __init __xbc_parse_value(char **__v, char **__n)
{
        char *p, *v = *__v;
        int c, quotes = 0;

        v = skip_spaces(v);
        while (*v == '#') {
                v = skip_comment(v);
                v = skip_spaces(v);
        }
        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;

        do {
                c = __xbc_parse_value(__v, &next);
                if (c < 0)
                        return c;

                node = xbc_add_sibling(*__v, XBC_VALUE);
                if (!node)
                        return -ENOMEM;
                *__v = next;
        } while (c == ',');
        node->next = 0;

        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);
                if (child && xbc_node_is_value(child))
                        return xbc_parse_error("Subkey is mixed with value", k);
                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;

        child = xbc_node_get_child(last_parent);
        if (child) {
                if (xbc_node_is_key(child))
                        return xbc_parse_error("Value is mixed with subkey", v);
                else if (op == '=')
                        return xbc_parse_error("Value is redefined", v);
        }

        c = __xbc_parse_value(&v, &next);
        if (c < 0)
                return c;

        if (op == ':' && child) {
                xbc_init_node(child, v, XBC_VALUE);
        } else if (!xbc_add_sibling(v, XBC_VALUE))
                return -ENOMEM;

        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);
}

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

        /* Brace closing */
        if (brace_index) {
                n = &xbc_nodes[open_brace[brace_index]];
                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;
        }

        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));
                }
        }

        /* 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;
}

/**
 * xbc_destroy_all() - 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_destroy_all(void)
{
        xbc_data = NULL;
        xbc_data_size = 0;
        xbc_node_num = 0;
        memblock_free(__pa(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
 * @buf: boot config text
 * @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 @buf. @buf must be a
 * null terminated string and 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(char *buf, const char **emsg, int *epos)
{
        char *p, *q;
        int ret, c;

        if (epos)
                *epos = -1;

        if (xbc_data) {
                if (emsg)
                        *emsg = "Bootconfig is already initialized";
                return -EBUSY;
        }

        ret = strlen(buf);
        if (ret > XBC_DATA_MAX - 1 || ret == 0) {
                if (emsg)
                        *emsg = ret ? "Config data is too big" :
                                "Config data is empty";
                return -ERANGE;
        }

        xbc_nodes = memblock_alloc(sizeof(struct xbc_node) * XBC_NODE_MAX,
                                   SMP_CACHE_BYTES);
        if (!xbc_nodes) {
                if (emsg)
                        *emsg = "Failed to allocate bootconfig nodes";
                return -ENOMEM;
        }
        memset(xbc_nodes, 0, sizeof(struct xbc_node) * XBC_NODE_MAX);
        xbc_data = buf;
        xbc_data_size = ret + 1;
        last_parent = NULL;

        p = buf;
        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)
                ret = xbc_verify_tree();

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

        return ret;
}

/**
 * xbc_debug_dump() - Dump current XBC node list
 *
 * Dump the current XBC node list on printk buffer for debug.
 */
void __init xbc_debug_dump(void)
{
        int i;

        for (i = 0; i < xbc_node_num; i++) {
                pr_debug("[%d] %s (%s) .next=%d, .child=%d .parent=%d\n", i,
                        xbc_node_get_data(xbc_nodes + i),
                        xbc_node_is_value(xbc_nodes + i) ? "value" : "key",
                        xbc_nodes[i].next, xbc_nodes[i].child,
                        xbc_nodes[i].parent);
        }
}