1 /* C string table handling.
2 Copyright (C) 2000-2024 Free Software Foundation, Inc.
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)
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.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, see <https://www.gnu.org/licenses/>. */
27 #include <sys/cdefs.h>
28 #include <sys/param.h>
45 struct memoryblock *next;
53 struct memoryblock *memory;
62 /* Cache for the pagesize. We correct this value a bit so that `malloc'
63 is not allocating more than a page. */
67 #include <programs/xmalloc.h>
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);
74 /* Free resources allocated for C string table ST. */
75 extern void strtabfree (struct Strtab *st);
77 /* Add string STR (length LEN is != 0) to C string table ST. */
78 extern struct Strent *strtabadd (struct Strtab *st, const char *str,
81 /* Finalize string table ST and store size in *SIZE and return a pointer. */
82 extern void *strtabfinalize (struct Strtab *st, size_t *size);
84 /* Get offset in string table for string associated with SE. */
85 extern size_t strtaboffset (struct Strent *se);
95 ps = sysconf (_SC_PAGESIZE) - 2 * sizeof (void *);
96 assert (sizeof (struct memoryblock) < ps);
99 ret = (struct Strtab *) calloc (1, sizeof (struct Strtab));
103 ret->null.string = "";
110 morememory (struct Strtab *st, size_t len)
112 struct memoryblock *newmem;
116 newmem = (struct memoryblock *) malloc (len);
120 newmem->next = st->memory;
122 st->backp = newmem->memory;
123 st->left = len - offsetof (struct memoryblock, memory);
128 strtabfree (struct Strtab *st)
130 struct memoryblock *mb = st->memory;
143 static struct Strent *
144 newstring (struct Strtab *st, const char *str, size_t len)
146 struct Strent *newstr;
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));
156 /* Make sure there is enough room in the memory block. */
157 if (st->left < align + sizeof (struct Strent) + len)
159 morememory (st, sizeof (struct Strent) + len);
163 /* Create the reserved string. */
164 newstr = (struct Strent *) (st->backp + align);
165 newstr->string = str;
169 newstr->right = NULL;
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;
181 /* XXX This function should definitely be rewritten to use a balancing
182 tree algorithm (AVL, red-black trees). For now a simple, correct
183 implementation is enough. */
184 static struct Strent **
185 searchstring (struct Strent **sep, struct Strent *newstr)
196 /* Compare the strings. */
197 cmpres = memcmp ((*sep)->reverse, newstr->reverse,
198 MIN ((*sep)->len, newstr->len) - 1);
200 /* We found a matching string. */
203 return searchstring (&(*sep)->left, newstr);
205 return searchstring (&(*sep)->right, newstr);
209 /* Add new string. The actual string is assumed to be permanent. */
211 strtabadd (struct Strtab *st, const char *str, size_t len)
213 struct Strent *newstr;
216 /* Compute the string length if the caller doesn't know it. */
218 len = strlen (str) + 1;
220 /* Make sure all "" strings get offset 0. */
224 /* Allocate memory for the new string and its associated information. */
225 newstr = newstring (st, str, len);
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);
233 /* This is not the same entry. This means we have a prefix match. */
234 if ((*sep)->len > newstr->len)
238 for (subs = (*sep)->next; subs; subs = subs->next)
239 if (subs->len == newstr->len)
241 /* We have an exact match with a substring. Free the memory
243 st->left += st->backp - (char *) newstr;
244 st->backp = (char *) newstr;
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;
254 newstr->next = (*sep)->next;
255 (*sep)->next = newstr;
257 else if ((*sep)->len != newstr->len)
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. */
262 st->total += newstr->len - (*sep)->len;
264 newstr->left = (*sep)->left;
265 newstr->right = (*sep)->right;
270 /* We have an exact match. Free the memory we allocated. */
271 st->left += st->backp - (char *) newstr;
272 st->backp = (char *) newstr;
278 st->total += newstr->len;
285 copystrings (struct Strent *nodep, char **freep, size_t *offsetp)
289 if (nodep->left != NULL)
290 copystrings (nodep->left, freep, offsetp);
292 /* Process the current node. */
293 nodep->offset = *offsetp;
294 *freep = (char *) mempcpy (*freep, nodep->string, nodep->len);
295 *offsetp += nodep->len;
297 for (subs = nodep->next; subs != NULL; subs = subs->next)
299 assert (subs->len < nodep->len);
300 subs->offset = nodep->offset + nodep->len - subs->len;
303 if (nodep->right != NULL)
304 copystrings (nodep->right, freep, offsetp);
309 strtabfinalize (struct Strtab *st, size_t *size)
315 /* Fill in the information. */
316 endp = retval = (char *) xmalloc (st->total + 1);
318 /* Always put an empty string at the beginning so that a zero offset
322 /* Now run through the tree and add all the string while also updating
323 the offset members of the elfstrent records. */
325 copystrings (st->root, &endp, ©len);
326 assert (copylen == st->total + 1);
327 assert (endp == retval + st->total + 1);
335 strtaboffset (struct Strent *se)