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53e1b683 | 1 | /* SPDX-License-Identifier: LGPL-2.1+ */ |
955bd501 KS |
2 | /*** |
3 | This file is part of systemd. | |
4 | ||
1298001e | 5 | Copyright 2012 Kay Sievers <kay@vrfy.org> |
955bd501 KS |
6 | |
7 | systemd is free software; you can redistribute it and/or modify it | |
8 | under the terms of the GNU Lesser General Public License as published by | |
9 | the Free Software Foundation; either version 2.1 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | systemd is distributed in the hope that it will be useful, but | |
13 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
15 | Lesser General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU Lesser General Public License | |
18 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
19 | ***/ | |
20 | ||
11c3a366 | 21 | #include <errno.h> |
955bd501 KS |
22 | #include <stdlib.h> |
23 | #include <string.h> | |
24 | ||
b5efdb8a | 25 | #include "alloc-util.h" |
955bd501 | 26 | #include "strbuf.h" |
d6c5d19b | 27 | #include "util.h" |
955bd501 | 28 | |
4693cfb3 | 29 | /* |
ab06eef8 | 30 | * Strbuf stores given strings in a single continuous allocated memory |
f1c0ece1 KS |
31 | * area. Identical strings are de-duplicated and return the same offset |
32 | * as the first string stored. If the tail of a string already exists | |
33 | * in the buffer, the tail is returned. | |
4693cfb3 | 34 | * |
f1c0ece1 KS |
35 | * A trie (http://en.wikipedia.org/wiki/Trie) is used to maintain the |
36 | * information about the stored strings. | |
4693cfb3 KS |
37 | * |
38 | * Example of udev rules: | |
39 | * $ ./udevadm test . | |
40 | * ... | |
41 | * read rules file: /usr/lib/udev/rules.d/99-systemd.rules | |
42 | * rules contain 196608 bytes tokens (16384 * 12 bytes), 39742 bytes strings | |
43 | * 23939 strings (207859 bytes), 20404 de-duplicated (171653 bytes), 3536 trie nodes used | |
44 | * ... | |
45 | */ | |
46 | ||
955bd501 KS |
47 | struct strbuf *strbuf_new(void) { |
48 | struct strbuf *str; | |
49 | ||
2fb076ad | 50 | str = new(struct strbuf, 1); |
955bd501 KS |
51 | if (!str) |
52 | return NULL; | |
2fb076ad ZJS |
53 | *str = (struct strbuf) { |
54 | .buf = new0(char, 1), | |
55 | .root = new0(struct strbuf_node, 1), | |
56 | .len = 1, | |
57 | .nodes_count = 1, | |
58 | }; | |
59 | if (!str->buf || !str->root) { | |
60 | free(str->buf); | |
61 | free(str->root); | |
62 | return mfree(str); | |
63 | } | |
955bd501 | 64 | |
955bd501 | 65 | return str; |
955bd501 KS |
66 | } |
67 | ||
2fb076ad | 68 | static struct strbuf_node* strbuf_node_cleanup(struct strbuf_node *node) { |
955bd501 KS |
69 | size_t i; |
70 | ||
71 | for (i = 0; i < node->children_count; i++) | |
72 | strbuf_node_cleanup(node->children[i].child); | |
73 | free(node->children); | |
2fb076ad | 74 | return mfree(node); |
955bd501 KS |
75 | } |
76 | ||
4693cfb3 | 77 | /* clean up trie data, leave only the string buffer */ |
955bd501 KS |
78 | void strbuf_complete(struct strbuf *str) { |
79 | if (!str) | |
80 | return; | |
81 | if (str->root) | |
2fb076ad | 82 | str->root = strbuf_node_cleanup(str->root); |
955bd501 KS |
83 | } |
84 | ||
4693cfb3 | 85 | /* clean up everything */ |
955bd501 | 86 | void strbuf_cleanup(struct strbuf *str) { |
2fb076ad | 87 | strbuf_complete(str); |
955bd501 KS |
88 | free(str->buf); |
89 | free(str); | |
90 | } | |
91 | ||
3c8bed4e ZJS |
92 | static int strbuf_children_cmp(const struct strbuf_child_entry *n1, |
93 | const struct strbuf_child_entry *n2) { | |
955bd501 KS |
94 | return n1->c - n2->c; |
95 | } | |
96 | ||
3c8bed4e ZJS |
97 | static void bubbleinsert(struct strbuf_node *node, |
98 | uint8_t c, | |
99 | struct strbuf_node *node_child) { | |
100 | ||
101 | struct strbuf_child_entry new = { | |
102 | .c = c, | |
103 | .child = node_child, | |
104 | }; | |
105 | int left = 0, right = node->children_count; | |
106 | ||
107 | while (right > left) { | |
108 | int middle = (right + left) / 2 ; | |
109 | if (strbuf_children_cmp(&node->children[middle], &new) <= 0) | |
110 | left = middle + 1; | |
111 | else | |
112 | right = middle; | |
113 | } | |
114 | ||
115 | memmove(node->children + left + 1, node->children + left, | |
116 | sizeof(struct strbuf_child_entry) * (node->children_count - left)); | |
117 | node->children[left] = new; | |
118 | ||
313cefa1 | 119 | node->children_count++; |
3c8bed4e ZJS |
120 | } |
121 | ||
4693cfb3 | 122 | /* add string, return the index/offset into the buffer */ |
955bd501 KS |
123 | ssize_t strbuf_add_string(struct strbuf *str, const char *s, size_t len) { |
124 | uint8_t c; | |
125 | struct strbuf_node *node; | |
126 | size_t depth; | |
127 | char *buf_new; | |
128 | struct strbuf_child_entry *child; | |
129 | struct strbuf_node *node_child; | |
130 | ssize_t off; | |
131 | ||
132 | if (!str->root) | |
133 | return -EINVAL; | |
134 | ||
135 | /* search string; start from last character to find possibly matching tails */ | |
435ce146 | 136 | |
955bd501 | 137 | str->in_count++; |
435ce146 ZJS |
138 | if (len == 0) { |
139 | str->dedup_count++; | |
140 | return 0; | |
141 | } | |
955bd501 KS |
142 | str->in_len += len; |
143 | ||
144 | node = str->root; | |
955bd501 KS |
145 | for (depth = 0; depth <= len; depth++) { |
146 | struct strbuf_child_entry search; | |
147 | ||
148 | /* match against current node */ | |
149 | off = node->value_off + node->value_len - len; | |
150 | if (depth == len || (node->value_len >= len && memcmp(str->buf + off, s, len) == 0)) { | |
151 | str->dedup_len += len; | |
152 | str->dedup_count++; | |
153 | return off; | |
154 | } | |
155 | ||
c45606eb LR |
156 | c = s[len - 1 - depth]; |
157 | ||
955bd501 | 158 | /* lookup child node */ |
955bd501 | 159 | search.c = c; |
d6c5d19b ZJS |
160 | child = bsearch_safe(&search, node->children, node->children_count, |
161 | sizeof(struct strbuf_child_entry), | |
162 | (__compar_fn_t) strbuf_children_cmp); | |
955bd501 KS |
163 | if (!child) |
164 | break; | |
165 | node = child->child; | |
166 | } | |
167 | ||
168 | /* add new string */ | |
169 | buf_new = realloc(str->buf, str->len + len+1); | |
170 | if (!buf_new) | |
171 | return -ENOMEM; | |
172 | str->buf = buf_new; | |
173 | off = str->len; | |
174 | memcpy(str->buf + off, s, len); | |
175 | str->len += len; | |
176 | str->buf[str->len++] = '\0'; | |
177 | ||
178 | /* new node */ | |
2fb076ad | 179 | node_child = new(struct strbuf_node, 1); |
955bd501 KS |
180 | if (!node_child) |
181 | return -ENOMEM; | |
2fb076ad ZJS |
182 | *node_child = (struct strbuf_node) { |
183 | .value_off = off, | |
184 | .value_len = len, | |
185 | }; | |
955bd501 KS |
186 | |
187 | /* extend array, add new entry, sort for bisection */ | |
62d74c78 | 188 | child = reallocarray(node->children, node->children_count + 1, sizeof(struct strbuf_child_entry)); |
a9c307e5 ZJS |
189 | if (!child) { |
190 | free(node_child); | |
955bd501 | 191 | return -ENOMEM; |
a9c307e5 ZJS |
192 | } |
193 | ||
194 | str->nodes_count++; | |
195 | ||
955bd501 | 196 | node->children = child; |
3c8bed4e | 197 | bubbleinsert(node, c, node_child); |
955bd501 KS |
198 | |
199 | return off; | |
200 | } |