1 #include "util.h"
2 #include "string.h"
3 #include "strfilter.h"
4
5 /* Operators */
6 static const char *OP_and = "&"; /* Logical AND */
7 static const char *OP_or = "|"; /* Logical OR */
8 static const char *OP_not = "!"; /* Logical NOT */
9
10 #define is_operator(c) ((c) == '|' || (c) == '&' || (c) == '!')
11 #define is_separator(c) (is_operator(c) || (c) == '(' || (c) == ')')
12
strfilter_node__delete(struct strfilter_node * node)13 static void strfilter_node__delete(struct strfilter_node *node)
14 {
15 if (node) {
16 if (node->p && !is_operator(*node->p))
17 zfree((char **)&node->p);
18 strfilter_node__delete(node->l);
19 strfilter_node__delete(node->r);
20 free(node);
21 }
22 }
23
strfilter__delete(struct strfilter * filter)24 void strfilter__delete(struct strfilter *filter)
25 {
26 if (filter) {
27 strfilter_node__delete(filter->root);
28 free(filter);
29 }
30 }
31
get_token(const char * s,const char ** e)32 static const char *get_token(const char *s, const char **e)
33 {
34 const char *p;
35
36 while (isspace(*s)) /* Skip spaces */
37 s++;
38
39 if (*s == '\0') {
40 p = s;
41 goto end;
42 }
43
44 p = s + 1;
45 if (!is_separator(*s)) {
46 /* End search */
47 retry:
48 while (*p && !is_separator(*p) && !isspace(*p))
49 p++;
50 /* Escape and special case: '!' is also used in glob pattern */
51 if (*(p - 1) == '\\' || (*p == '!' && *(p - 1) == '[')) {
52 p++;
53 goto retry;
54 }
55 }
56 end:
57 *e = p;
58 return s;
59 }
60
strfilter_node__alloc(const char * op,struct strfilter_node * l,struct strfilter_node * r)61 static struct strfilter_node *strfilter_node__alloc(const char *op,
62 struct strfilter_node *l,
63 struct strfilter_node *r)
64 {
65 struct strfilter_node *node = zalloc(sizeof(*node));
66
67 if (node) {
68 node->p = op;
69 node->l = l;
70 node->r = r;
71 }
72
73 return node;
74 }
75
strfilter_node__new(const char * s,const char ** ep)76 static struct strfilter_node *strfilter_node__new(const char *s,
77 const char **ep)
78 {
79 struct strfilter_node root, *cur, *last_op;
80 const char *e;
81
82 if (!s)
83 return NULL;
84
85 memset(&root, 0, sizeof(root));
86 last_op = cur = &root;
87
88 s = get_token(s, &e);
89 while (*s != '\0' && *s != ')') {
90 switch (*s) {
91 case '&': /* Exchg last OP->r with AND */
92 if (!cur->r || !last_op->r)
93 goto error;
94 cur = strfilter_node__alloc(OP_and, last_op->r, NULL);
95 if (!cur)
96 goto nomem;
97 last_op->r = cur;
98 last_op = cur;
99 break;
100 case '|': /* Exchg the root with OR */
101 if (!cur->r || !root.r)
102 goto error;
103 cur = strfilter_node__alloc(OP_or, root.r, NULL);
104 if (!cur)
105 goto nomem;
106 root.r = cur;
107 last_op = cur;
108 break;
109 case '!': /* Add NOT as a leaf node */
110 if (cur->r)
111 goto error;
112 cur->r = strfilter_node__alloc(OP_not, NULL, NULL);
113 if (!cur->r)
114 goto nomem;
115 cur = cur->r;
116 break;
117 case '(': /* Recursively parses inside the parenthesis */
118 if (cur->r)
119 goto error;
120 cur->r = strfilter_node__new(s + 1, &s);
121 if (!s)
122 goto nomem;
123 if (!cur->r || *s != ')')
124 goto error;
125 e = s + 1;
126 break;
127 default:
128 if (cur->r)
129 goto error;
130 cur->r = strfilter_node__alloc(NULL, NULL, NULL);
131 if (!cur->r)
132 goto nomem;
133 cur->r->p = strndup(s, e - s);
134 if (!cur->r->p)
135 goto nomem;
136 }
137 s = get_token(e, &e);
138 }
139 if (!cur->r)
140 goto error;
141 *ep = s;
142 return root.r;
143 nomem:
144 s = NULL;
145 error:
146 *ep = s;
147 strfilter_node__delete(root.r);
148 return NULL;
149 }
150
151 /*
152 * Parse filter rule and return new strfilter.
153 * Return NULL if fail, and *ep == NULL if memory allocation failed.
154 */
strfilter__new(const char * rules,const char ** err)155 struct strfilter *strfilter__new(const char *rules, const char **err)
156 {
157 struct strfilter *filter = zalloc(sizeof(*filter));
158 const char *ep = NULL;
159
160 if (filter)
161 filter->root = strfilter_node__new(rules, &ep);
162
163 if (!filter || !filter->root || *ep != '\0') {
164 if (err)
165 *err = ep;
166 strfilter__delete(filter);
167 filter = NULL;
168 }
169
170 return filter;
171 }
172
strfilter__append(struct strfilter * filter,bool _or,const char * rules,const char ** err)173 static int strfilter__append(struct strfilter *filter, bool _or,
174 const char *rules, const char **err)
175 {
176 struct strfilter_node *right, *root;
177 const char *ep = NULL;
178
179 if (!filter || !rules)
180 return -EINVAL;
181
182 right = strfilter_node__new(rules, &ep);
183 if (!right || *ep != '\0') {
184 if (err)
185 *err = ep;
186 goto error;
187 }
188 root = strfilter_node__alloc(_or ? OP_or : OP_and, filter->root, right);
189 if (!root) {
190 ep = NULL;
191 goto error;
192 }
193
194 filter->root = root;
195 return 0;
196
197 error:
198 strfilter_node__delete(right);
199 return ep ? -EINVAL : -ENOMEM;
200 }
201
strfilter__or(struct strfilter * filter,const char * rules,const char ** err)202 int strfilter__or(struct strfilter *filter, const char *rules, const char **err)
203 {
204 return strfilter__append(filter, true, rules, err);
205 }
206
strfilter__and(struct strfilter * filter,const char * rules,const char ** err)207 int strfilter__and(struct strfilter *filter, const char *rules,
208 const char **err)
209 {
210 return strfilter__append(filter, false, rules, err);
211 }
212
strfilter_node__compare(struct strfilter_node * node,const char * str)213 static bool strfilter_node__compare(struct strfilter_node *node,
214 const char *str)
215 {
216 if (!node || !node->p)
217 return false;
218
219 switch (*node->p) {
220 case '|': /* OR */
221 return strfilter_node__compare(node->l, str) ||
222 strfilter_node__compare(node->r, str);
223 case '&': /* AND */
224 return strfilter_node__compare(node->l, str) &&
225 strfilter_node__compare(node->r, str);
226 case '!': /* NOT */
227 return !strfilter_node__compare(node->r, str);
228 default:
229 return strglobmatch(str, node->p);
230 }
231 }
232
233 /* Return true if STR matches the filter rules */
strfilter__compare(struct strfilter * filter,const char * str)234 bool strfilter__compare(struct strfilter *filter, const char *str)
235 {
236 if (!filter)
237 return false;
238 return strfilter_node__compare(filter->root, str);
239 }
240
241 static int strfilter_node__sprint(struct strfilter_node *node, char *buf);
242
243 /* sprint node in parenthesis if needed */
strfilter_node__sprint_pt(struct strfilter_node * node,char * buf)244 static int strfilter_node__sprint_pt(struct strfilter_node *node, char *buf)
245 {
246 int len;
247 int pt = node->r ? 2 : 0; /* don't need to check node->l */
248
249 if (buf && pt)
250 *buf++ = '(';
251 len = strfilter_node__sprint(node, buf);
252 if (len < 0)
253 return len;
254 if (buf && pt)
255 *(buf + len) = ')';
256 return len + pt;
257 }
258
strfilter_node__sprint(struct strfilter_node * node,char * buf)259 static int strfilter_node__sprint(struct strfilter_node *node, char *buf)
260 {
261 int len = 0, rlen;
262
263 if (!node || !node->p)
264 return -EINVAL;
265
266 switch (*node->p) {
267 case '|':
268 case '&':
269 len = strfilter_node__sprint_pt(node->l, buf);
270 if (len < 0)
271 return len;
272 __fallthrough;
273 case '!':
274 if (buf) {
275 *(buf + len++) = *node->p;
276 buf += len;
277 } else
278 len++;
279 rlen = strfilter_node__sprint_pt(node->r, buf);
280 if (rlen < 0)
281 return rlen;
282 len += rlen;
283 break;
284 default:
285 len = strlen(node->p);
286 if (buf)
287 strcpy(buf, node->p);
288 }
289
290 return len;
291 }
292
strfilter__string(struct strfilter * filter)293 char *strfilter__string(struct strfilter *filter)
294 {
295 int len;
296 char *ret = NULL;
297
298 len = strfilter_node__sprint(filter->root, NULL);
299 if (len < 0)
300 return NULL;
301
302 ret = malloc(len + 1);
303 if (ret)
304 strfilter_node__sprint(filter->root, ret);
305
306 return ret;
307 }
308