// SPDX-License-Identifier: GPL-2.0 /* * Extra Boot Config * Masami Hiramatsu <mhiramat@kernel.org> */ #define pr_fmt(fmt) "bootconfig: " fmt #include <linux/bug.h> #include <linux/ctype.h> #include <linux/errno.h> #include <linux/kernel.h> #include <linux/printk.h> #include <linux/bootconfig.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[XBC_NODE_MAX] __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 int __init xbc_parse_error(const char *msg, const char *p) { int pos = p - xbc_data; pr_err("Parse error at pos %d: %s\n", pos, msg); 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 struct xbc_node * __init xbc_add_node(char *data, u32 flag) { struct xbc_node *node; unsigned long offset; if (xbc_node_num == XBC_NODE_MAX) return NULL; node = &xbc_nodes[xbc_node_num++]; offset = data - xbc_data; node->data = (u16)offset; if (WARN_ON(offset >= XBC_DATA_MAX)) return NULL; node->data |= flag; node->child = 0; node->next = 0; 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(void) { /* Mark the last key as open brace */ last_parent->next = XBC_NODE_MAX; return 0; } static int __init __xbc_close_brace(char *p) { struct xbc_node *node; if (!last_parent || last_parent->next != XBC_NODE_MAX) return xbc_parse_error("Unexpected closing brace", p); node = last_parent; node->next = 0; do { node = xbc_node_get_parent(node); } while (node && node->next != XBC_NODE_MAX); last_parent = node; 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)) { v = strim(v); *p++ = '\0'; 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; 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 node = find_match_node(xbc_node_get_child(last_parent), 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) { struct xbc_node *prev_parent = last_parent; struct xbc_node *node; char *next; int c, ret; ret = __xbc_parse_keys(*k); if (ret) return ret; c = __xbc_parse_value(&v, &next); if (c < 0) return c; node = xbc_add_sibling(v, XBC_VALUE); if (!node) 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(); } 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; /* 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; memset(xbc_nodes, 0, sizeof(xbc_nodes)); } /** * xbc_init() - Parse given XBC file and build XBC internal tree * @buf: boot config text * * This parses the boot config text in @buf. @buf must be a * null terminated string and smaller than XBC_DATA_MAX. * Return 0 if succeeded, or -errno if there is any error. */ int __init xbc_init(char *buf) { char *p, *q; int ret, c; if (xbc_data) { pr_err("Error: bootconfig is already initialized.\n"); return -EBUSY; } ret = strlen(buf); if (ret > XBC_DATA_MAX - 1 || ret == 0) { pr_err("Error: Config data is %s.\n", ret ? "too big" : "empty"); return -ERANGE; } 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 '=': ret = xbc_parse_kv(&p, q); break; case '{': ret = xbc_open_brace(&p, q); break; case '#': q = skip_comment(q); /* fall through */ 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) xbc_destroy_all(); 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); } }