1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
4 This file is part of systemd.
6 Copyright 2012 Kay Sievers <kay.sievers@vrfy.org>
8 systemd is free software; you can redistribute it and/or modify it
9 under the terms of the GNU Lesser General Public License as published by
10 the Free Software Foundation; either version 2.1 of the License, or
11 (at your option) any later version.
13 systemd is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 Lesser General Public License for more details.
18 You should have received a copy of the GNU Lesser General Public License
19 along with systemd; If not, see <http://www.gnu.org/licenses/>.
29 * Strbuf stores given strings in a single continous allocated memory
30 * area. Identical strings are de-duplicated. If the tail of a string
31 * already exist in the buffer, the tail is returned.
33 * A Particia Trie is used to maintain the information about the stored
36 * Example of udev rules:
39 * read rules file: /usr/lib/udev/rules.d/99-systemd.rules
40 * rules contain 196608 bytes tokens (16384 * 12 bytes), 39742 bytes strings
41 * 23939 strings (207859 bytes), 20404 de-duplicated (171653 bytes), 3536 trie nodes used
45 struct strbuf *strbuf_new(void) {
48 str = new0(struct strbuf, 1);
52 str->buf = new0(char, 1);
57 str->root = new0(struct strbuf_node, 1);
69 static void strbuf_node_cleanup(struct strbuf_node *node) {
72 for (i = 0; i < node->children_count; i++)
73 strbuf_node_cleanup(node->children[i].child);
78 /* clean up trie data, leave only the string buffer */
79 void strbuf_complete(struct strbuf *str) {
83 strbuf_node_cleanup(str->root);
87 /* clean up everything */
88 void strbuf_cleanup(struct strbuf *str) {
92 strbuf_node_cleanup(str->root);
97 static int strbuf_children_cmp(const void *v1, const void *v2) {
98 const struct strbuf_child_entry *n1 = v1;
99 const struct strbuf_child_entry *n2 = v2;
101 return n1->c - n2->c;
104 /* add string, return the index/offset into the buffer */
105 ssize_t strbuf_add_string(struct strbuf *str, const char *s, size_t len) {
107 struct strbuf_node *node;
110 struct strbuf_child_entry *child;
111 struct strbuf_node *node_child;
117 /* search string; start from last character to find possibly matching tails */
125 for (depth = 0; depth <= len; depth++) {
126 struct strbuf_child_entry search;
128 /* match against current node */
129 off = node->value_off + node->value_len - len;
130 if (depth == len || (node->value_len >= len && memcmp(str->buf + off, s, len) == 0)) {
131 str->dedup_len += len;
136 /* lookup child node */
137 c = s[len - 1 - depth];
139 child = bsearch(&search, node->children, node->children_count, sizeof(struct strbuf_child_entry),
140 strbuf_children_cmp);
147 buf_new = realloc(str->buf, str->len + len+1);
152 memcpy(str->buf + off, s, len);
154 str->buf[str->len++] = '\0';
157 node_child = new0(struct strbuf_node, 1);
161 node_child->value_off = off;
162 node_child->value_len = len;
164 /* extend array, add new entry, sort for bisection */
165 child = realloc(node->children, (node->children_count + 1) * sizeof(struct strbuf_child_entry));
168 node->children = child;
169 node->children[node->children_count].c = c;
170 node->children[node->children_count].child = node_child;
171 node->children_count++;
172 qsort(node->children, node->children_count, sizeof(struct strbuf_child_entry), strbuf_children_cmp);