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6b98979f | 1 | /* C string table handling. |
6d7e8eda | 2 | Copyright (C) 2000-2023 Free Software Foundation, Inc. |
6b98979f UD |
3 | |
4 | This program is free software; you can redistribute it and/or modify | |
5 | it under the terms of the GNU General Public License as published by | |
6 | the Free Software Foundation; either version 2, or (at your option) | |
7 | any later version. | |
8 | ||
9 | This program is distributed in the hope that it will be useful, | |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | GNU General Public License for more details. | |
13 | ||
14 | You should have received a copy of the GNU General Public License | |
5a82c748 | 15 | along with this program; if not, see <https://www.gnu.org/licenses/>. */ |
6b98979f UD |
16 | |
17 | #ifdef HAVE_CONFIG_H | |
18 | # include <config.h> | |
19 | #endif | |
20 | ||
21 | #include <assert.h> | |
22 | #include <inttypes.h> | |
61c03724 | 23 | #include <stddef.h> |
6b98979f UD |
24 | #include <stdlib.h> |
25 | #include <string.h> | |
26 | #include <unistd.h> | |
0588dfe7 | 27 | #include <sys/cdefs.h> |
6b98979f UD |
28 | #include <sys/param.h> |
29 | ||
30 | ||
31 | struct Strent | |
32 | { | |
33 | const char *string; | |
34 | size_t len; | |
35 | struct Strent *next; | |
36 | struct Strent *left; | |
37 | struct Strent *right; | |
38 | size_t offset; | |
39 | char reverse[0]; | |
40 | }; | |
41 | ||
42 | ||
43 | struct memoryblock | |
44 | { | |
45 | struct memoryblock *next; | |
46 | char memory[0]; | |
47 | }; | |
48 | ||
49 | ||
50 | struct Strtab | |
51 | { | |
52 | struct Strent *root; | |
53 | struct memoryblock *memory; | |
54 | char *backp; | |
55 | size_t left; | |
56 | size_t total; | |
57 | ||
58 | struct Strent null; | |
59 | }; | |
60 | ||
61 | ||
62 | /* Cache for the pagesize. We correct this value a bit so that `malloc' | |
63 | is not allocating more than a page. */ | |
64 | static size_t ps; | |
65 | ||
66 | ||
6ff444c4 | 67 | #include <programs/xmalloc.h> |
6b98979f | 68 | |
f85a7105 AJ |
69 | /* Prototypes for our functions that are used from iconvconfig.c. If |
70 | you change these, change also iconvconfig.c. */ | |
71 | /* Create new C string table object in memory. */ | |
72 | extern struct Strtab *strtabinit (void); | |
73 | ||
74 | /* Free resources allocated for C string table ST. */ | |
75 | extern void strtabfree (struct Strtab *st); | |
76 | ||
77 | /* Add string STR (length LEN is != 0) to C string table ST. */ | |
78 | extern struct Strent *strtabadd (struct Strtab *st, const char *str, | |
79 | size_t len); | |
80 | ||
81 | /* Finalize string table ST and store size in *SIZE and return a pointer. */ | |
82 | extern void *strtabfinalize (struct Strtab *st, size_t *size); | |
83 | ||
84 | /* Get offset in string table for string associated with SE. */ | |
85 | extern size_t strtaboffset (struct Strent *se); | |
86 | ||
6b98979f UD |
87 | |
88 | struct Strtab * | |
89 | strtabinit (void) | |
90 | { | |
71ce28fd UD |
91 | struct Strtab *ret; |
92 | ||
6b98979f UD |
93 | if (ps == 0) |
94 | { | |
61c03724 | 95 | ps = sysconf (_SC_PAGESIZE) - 2 * sizeof (void *); |
6b98979f UD |
96 | assert (sizeof (struct memoryblock) < ps); |
97 | } | |
98 | ||
71ce28fd UD |
99 | ret = (struct Strtab *) calloc (1, sizeof (struct Strtab)); |
100 | if (ret != NULL) | |
101 | { | |
102 | ret->null.len = 1; | |
103 | ret->null.string = ""; | |
104 | } | |
105 | return ret; | |
6b98979f UD |
106 | } |
107 | ||
108 | ||
109 | static void | |
110 | morememory (struct Strtab *st, size_t len) | |
111 | { | |
112 | struct memoryblock *newmem; | |
113 | ||
114 | if (len < ps) | |
115 | len = ps; | |
116 | newmem = (struct memoryblock *) malloc (len); | |
117 | if (newmem == NULL) | |
118 | abort (); | |
119 | ||
120 | newmem->next = st->memory; | |
121 | st->memory = newmem; | |
122 | st->backp = newmem->memory; | |
61c03724 | 123 | st->left = len - offsetof (struct memoryblock, memory); |
6b98979f UD |
124 | } |
125 | ||
126 | ||
127 | void | |
128 | strtabfree (struct Strtab *st) | |
129 | { | |
130 | struct memoryblock *mb = st->memory; | |
131 | ||
132 | while (mb != NULL) | |
133 | { | |
134 | void *old = mb; | |
135 | mb = mb->next; | |
136 | free (old); | |
137 | } | |
138 | ||
139 | free (st); | |
140 | } | |
141 | ||
142 | ||
143 | static struct Strent * | |
144 | newstring (struct Strtab *st, const char *str, size_t len) | |
145 | { | |
146 | struct Strent *newstr; | |
147 | size_t align; | |
148 | int i; | |
149 | ||
6b98979f UD |
150 | /* Compute the amount of padding needed to make the structure aligned. */ |
151 | align = ((__alignof__ (struct Strent) | |
152 | - (((uintptr_t) st->backp) | |
153 | & (__alignof__ (struct Strent) - 1))) | |
154 | & (__alignof__ (struct Strent) - 1)); | |
155 | ||
156 | /* Make sure there is enough room in the memory block. */ | |
157 | if (st->left < align + sizeof (struct Strent) + len) | |
158 | { | |
159 | morememory (st, sizeof (struct Strent) + len); | |
160 | align = 0; | |
161 | } | |
162 | ||
163 | /* Create the reserved string. */ | |
164 | newstr = (struct Strent *) (st->backp + align); | |
165 | newstr->string = str; | |
166 | newstr->len = len; | |
167 | newstr->next = NULL; | |
168 | newstr->left = NULL; | |
169 | newstr->right = NULL; | |
170 | newstr->offset = 0; | |
171 | for (i = len - 2; i >= 0; --i) | |
172 | newstr->reverse[i] = str[len - 2 - i]; | |
173 | newstr->reverse[len - 1] = '\0'; | |
174 | st->backp += align + sizeof (struct Strent) + len; | |
175 | st->left -= align + sizeof (struct Strent) + len; | |
176 | ||
177 | return newstr; | |
178 | } | |
179 | ||
180 | ||
181 | /* XXX This function should definitely be rewritten to use a balancing | |
c0c3f78a | 182 | tree algorithm (AVL, red-black trees). For now a simple, correct |
6b98979f UD |
183 | implementation is enough. */ |
184 | static struct Strent ** | |
185 | searchstring (struct Strent **sep, struct Strent *newstr) | |
186 | { | |
187 | int cmpres; | |
188 | ||
189 | /* More strings? */ | |
190 | if (*sep == NULL) | |
191 | { | |
192 | *sep = newstr; | |
193 | return sep; | |
194 | } | |
195 | ||
196 | /* Compare the strings. */ | |
197 | cmpres = memcmp ((*sep)->reverse, newstr->reverse, | |
c06a49c5 | 198 | MIN ((*sep)->len, newstr->len) - 1); |
6b98979f UD |
199 | if (cmpres == 0) |
200 | /* We found a matching string. */ | |
201 | return sep; | |
202 | else if (cmpres > 0) | |
203 | return searchstring (&(*sep)->left, newstr); | |
204 | else | |
205 | return searchstring (&(*sep)->right, newstr); | |
206 | } | |
207 | ||
208 | ||
209 | /* Add new string. The actual string is assumed to be permanent. */ | |
210 | struct Strent * | |
211 | strtabadd (struct Strtab *st, const char *str, size_t len) | |
212 | { | |
213 | struct Strent *newstr; | |
214 | struct Strent **sep; | |
215 | ||
71ce28fd UD |
216 | /* Compute the string length if the caller doesn't know it. */ |
217 | if (len == 0) | |
218 | len = strlen (str) + 1; | |
219 | ||
220 | /* Make sure all "" strings get offset 0. */ | |
221 | if (len == 1) | |
222 | return &st->null; | |
223 | ||
6b98979f UD |
224 | /* Allocate memory for the new string and its associated information. */ |
225 | newstr = newstring (st, str, len); | |
226 | ||
227 | /* Search in the array for the place to insert the string. If there | |
228 | is no string with matching prefix and no string with matching | |
229 | leading substring, create a new entry. */ | |
230 | sep = searchstring (&st->root, newstr); | |
231 | if (*sep != newstr) | |
232 | { | |
233 | /* This is not the same entry. This means we have a prefix match. */ | |
234 | if ((*sep)->len > newstr->len) | |
235 | { | |
71ce28fd UD |
236 | struct Strent *subs; |
237 | ||
238 | for (subs = (*sep)->next; subs; subs = subs->next) | |
239 | if (subs->len == newstr->len) | |
240 | { | |
241 | /* We have an exact match with a substring. Free the memory | |
242 | we allocated. */ | |
243 | st->left += st->backp - (char *) newstr; | |
244 | st->backp = (char *) newstr; | |
245 | ||
246 | return subs; | |
247 | } | |
248 | ||
6b98979f UD |
249 | /* We have a new substring. This means we don't need the reverse |
250 | string of this entry anymore. */ | |
251 | st->backp -= newstr->len; | |
252 | st->left += newstr->len; | |
253 | ||
254 | newstr->next = (*sep)->next; | |
255 | (*sep)->next = newstr; | |
256 | } | |
257 | else if ((*sep)->len != newstr->len) | |
258 | { | |
259 | /* When we get here it means that the string we are about to | |
260 | add has a common prefix with a string we already have but | |
261 | it is longer. In this case we have to put it first. */ | |
c06a49c5 | 262 | st->total += newstr->len - (*sep)->len; |
6b98979f | 263 | newstr->next = *sep; |
71ce28fd UD |
264 | newstr->left = (*sep)->left; |
265 | newstr->right = (*sep)->right; | |
6b98979f | 266 | *sep = newstr; |
6b98979f UD |
267 | } |
268 | else | |
269 | { | |
270 | /* We have an exact match. Free the memory we allocated. */ | |
271 | st->left += st->backp - (char *) newstr; | |
272 | st->backp = (char *) newstr; | |
273 | ||
274 | newstr = *sep; | |
275 | } | |
276 | } | |
277 | else | |
278 | st->total += newstr->len; | |
279 | ||
280 | return newstr; | |
281 | } | |
282 | ||
283 | ||
284 | static void | |
285 | copystrings (struct Strent *nodep, char **freep, size_t *offsetp) | |
286 | { | |
287 | struct Strent *subs; | |
288 | ||
289 | if (nodep->left != NULL) | |
290 | copystrings (nodep->left, freep, offsetp); | |
291 | ||
292 | /* Process the current node. */ | |
293 | nodep->offset = *offsetp; | |
294 | *freep = (char *) mempcpy (*freep, nodep->string, nodep->len); | |
295 | *offsetp += nodep->len; | |
296 | ||
297 | for (subs = nodep->next; subs != NULL; subs = subs->next) | |
298 | { | |
299 | assert (subs->len < nodep->len); | |
300 | subs->offset = nodep->offset + nodep->len - subs->len; | |
301 | } | |
302 | ||
303 | if (nodep->right != NULL) | |
304 | copystrings (nodep->right, freep, offsetp); | |
305 | } | |
306 | ||
307 | ||
308 | void * | |
309 | strtabfinalize (struct Strtab *st, size_t *size) | |
310 | { | |
311 | size_t copylen; | |
312 | char *endp; | |
313 | char *retval; | |
314 | ||
315 | /* Fill in the information. */ | |
316 | endp = retval = (char *) xmalloc (st->total + 1); | |
317 | ||
318 | /* Always put an empty string at the beginning so that a zero offset | |
319 | can mean error. */ | |
320 | *endp++ = '\0'; | |
321 | ||
322 | /* Now run through the tree and add all the string while also updating | |
323 | the offset members of the elfstrent records. */ | |
324 | copylen = 1; | |
325 | copystrings (st->root, &endp, ©len); | |
326 | assert (copylen == st->total + 1); | |
f9f7fcbe | 327 | assert (endp == retval + st->total + 1); |
6b98979f UD |
328 | *size = copylen; |
329 | ||
330 | return retval; | |
331 | } | |
332 | ||
333 | ||
334 | size_t | |
335 | strtaboffset (struct Strent *se) | |
336 | { | |
337 | return se->offset; | |
338 | } |