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1 /* ELF string table handling.
2    Copyright (C) 2000, 2001, 2002 Red Hat, Inc.
3    This file is part of Red Hat elfutils.
4    Written by Ulrich Drepper <drepper@redhat.com>, 2000.
5 
6    Red Hat elfutils is free software; you can redistribute it and/or modify
7    it under the terms of the GNU General Public License as published by the
8    Free Software Foundation; version 2 of the License.
9 
10    Red Hat elfutils is distributed in the hope that it will be useful, but
11    WITHOUT ANY WARRANTY; without even the implied warranty of
12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13    General Public License for more details.
14 
15    You should have received a copy of the GNU General Public License along
16    with Red Hat elfutils; if not, write to the Free Software Foundation,
17    Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
18 
19    In addition, as a special exception, Red Hat, Inc. gives You the
20    additional right to link the code of Red Hat elfutils with code licensed
21    under any Open Source Initiative certified open source license
22    (http://www.opensource.org/licenses/index.php) which requires the
23    distribution of source code with any binary distribution and to
24    distribute linked combinations of the two.  Non-GPL Code permitted under
25    this exception must only link to the code of Red Hat elfutils through
26    those well defined interfaces identified in the file named EXCEPTION
27    found in the source code files (the "Approved Interfaces").  The files
28    of Non-GPL Code may instantiate templates or use macros or inline
29    functions from the Approved Interfaces without causing the resulting
30    work to be covered by the GNU General Public License.  Only Red Hat,
31    Inc. may make changes or additions to the list of Approved Interfaces.
32    Red Hat's grant of this exception is conditioned upon your not adding
33    any new exceptions.  If you wish to add a new Approved Interface or
34    exception, please contact Red Hat.  You must obey the GNU General Public
35    License in all respects for all of the Red Hat elfutils code and other
36    code used in conjunction with Red Hat elfutils except the Non-GPL Code
37    covered by this exception.  If you modify this file, you may extend this
38    exception to your version of the file, but you are not obligated to do
39    so.  If you do not wish to provide this exception without modification,
40    you must delete this exception statement from your version and license
41    this file solely under the GPL without exception.
42 
43    Red Hat elfutils is an included package of the Open Invention Network.
44    An included package of the Open Invention Network is a package for which
45    Open Invention Network licensees cross-license their patents.  No patent
46    license is granted, either expressly or impliedly, by designation as an
47    included package.  Should you wish to participate in the Open Invention
48    Network licensing program, please visit www.openinventionnetwork.com
49    <http://www.openinventionnetwork.com>.  */
50 
51 #ifdef HAVE_CONFIG_H
52 # include <config.h>
53 #endif
54 
55 #include <assert.h>
56 #include <inttypes.h>
57 #include <libelf.h>
58 #include <stddef.h>
59 #include <stdlib.h>
60 #include <string.h>
61 #include <unistd.h>
62 #include <wchar.h>
63 #include <sys/param.h>
64 
65 #include "libebl.h"
66 #include <system.h>
67 
68 #ifndef MIN
69 # define MIN(a, b) ((a) < (b) ? (a) : (b))
70 #endif
71 
72 
73 struct Ebl_WStrent
74 {
75   const wchar_t *string;
76   size_t len;
77   struct Ebl_WStrent *next;
78   struct Ebl_WStrent *left;
79   struct Ebl_WStrent *right;
80   size_t offset;
81   wchar_t reverse[0];
82 };
83 
84 
85 struct memoryblock
86 {
87   struct memoryblock *next;
88   char memory[0];
89 };
90 
91 
92 struct Ebl_WStrtab
93 {
94   struct Ebl_WStrent *root;
95   struct memoryblock *memory;
96   char *backp;
97   size_t left;
98   size_t total;
99   bool nullstr;
100 
101   struct Ebl_WStrent null;
102 };
103 
104 
105 /* Cache for the pagesize.  We correct this value a bit so that `malloc'
106    is not allocating more than a page.  */
107 static size_t ps;
108 
109 
110 struct Ebl_WStrtab *
ebl_wstrtabinit(bool nullstr)111 ebl_wstrtabinit (bool nullstr)
112 {
113   struct Ebl_WStrtab *ret;
114 
115   if (ps == 0)
116     {
117       ps = sysconf (_SC_PAGESIZE) - 2 * sizeof (void *);
118       assert (sizeof (struct memoryblock) < ps);
119     }
120 
121   ret = (struct Ebl_WStrtab *) calloc (1, sizeof (struct Ebl_WStrtab));
122   if (ret != NULL)
123     {
124       ret->nullstr = nullstr;
125       if (nullstr)
126 	{
127 	  ret->null.len = 1;
128 	  ret->null.string = L"";
129 	}
130     }
131   return ret;
132 }
133 
134 
135 static int
morememory(struct Ebl_WStrtab * st,size_t len)136 morememory (struct Ebl_WStrtab *st, size_t len)
137 {
138   struct memoryblock *newmem;
139 
140   if (len < ps)
141     len = ps;
142   newmem = (struct memoryblock *) malloc (len);
143   if (newmem == NULL)
144     return 1;
145 
146   newmem->next = st->memory;
147   st->memory = newmem;
148   st->backp = newmem->memory;
149   st->left = len - offsetof (struct memoryblock, memory);
150 
151   return 0;
152 }
153 
154 
155 void
ebl_wstrtabfree(struct Ebl_WStrtab * st)156 ebl_wstrtabfree (struct Ebl_WStrtab *st)
157 {
158   struct memoryblock *mb = st->memory;
159 
160   while (mb != NULL)
161     {
162       void *old = mb;
163       mb = mb->next;
164       free (old);
165     }
166 
167   free (st);
168 }
169 
170 
171 static struct Ebl_WStrent *
newstring(struct Ebl_WStrtab * st,const wchar_t * str,size_t len)172 newstring (struct Ebl_WStrtab *st, const wchar_t *str, size_t len)
173 {
174   struct Ebl_WStrent *newstr;
175   size_t align;
176   int i;
177 
178   /* Compute the amount of padding needed to make the structure aligned.  */
179   align = ((__alignof__ (struct Ebl_WStrent)
180 	    - (((uintptr_t) st->backp)
181 	       & (__alignof__ (struct Ebl_WStrent) - 1)))
182 	   & (__alignof__ (struct Ebl_WStrent) - 1));
183 
184   /* Make sure there is enough room in the memory block.  */
185   if (st->left < align + sizeof (struct Ebl_WStrent) + len * sizeof (wchar_t))
186     {
187       if (morememory (st,
188 		      sizeof (struct Ebl_WStrent) + len * sizeof (wchar_t)))
189 	return NULL;
190 
191       align = 0;
192     }
193 
194   /* Create the reserved string.  */
195   newstr = (struct Ebl_WStrent *) (st->backp + align);
196   newstr->string = str;
197   newstr->len = len;
198   newstr->next = NULL;
199   newstr->left = NULL;
200   newstr->right = NULL;
201   newstr->offset = 0;
202   for (i = len - 2; i >= 0; --i)
203     newstr->reverse[i] = str[len - 2 - i];
204   newstr->reverse[len - 1] = L'\0';
205   st->backp += align + sizeof (struct Ebl_WStrent) + len * sizeof (wchar_t);
206   st->left -= align + sizeof (struct Ebl_WStrent) + len * sizeof (wchar_t);
207 
208   return newstr;
209 }
210 
211 
212 /* XXX This function should definitely be rewritten to use a balancing
213    tree algorith (AVL, red-black trees).  For now a simple, correct
214    implementation is enough.  */
215 static struct Ebl_WStrent **
searchstring(struct Ebl_WStrent ** sep,struct Ebl_WStrent * newstr)216 searchstring (struct Ebl_WStrent **sep, struct Ebl_WStrent *newstr)
217 {
218   int cmpres;
219 
220   /* More strings?  */
221   if (*sep == NULL)
222     {
223       *sep = newstr;
224       return sep;
225     }
226 
227   /* Compare the strings.  */
228   cmpres = wmemcmp ((*sep)->reverse, newstr->reverse,
229 		    MIN ((*sep)->len, newstr->len) - 1);
230   if (cmpres == 0)
231     /* We found a matching string.  */
232     return sep;
233   else if (cmpres > 0)
234     return searchstring (&(*sep)->left, newstr);
235   else
236     return searchstring (&(*sep)->right, newstr);
237 }
238 
239 
240 /* Add new string.  The actual string is assumed to be permanent.  */
241 struct Ebl_WStrent *
ebl_wstrtabadd(struct Ebl_WStrtab * st,const wchar_t * str,size_t len)242 ebl_wstrtabadd (struct Ebl_WStrtab *st, const wchar_t *str, size_t len)
243 {
244   struct Ebl_WStrent *newstr;
245   struct Ebl_WStrent **sep;
246 
247   /* Compute the string length if the caller doesn't know it.  */
248   if (len == 0)
249     len = wcslen (str) + 1;
250 
251   /* Make sure all "" strings get offset 0 but only if the table was
252      created with a special null entry in mind.  */
253   if (len == 1 && st->null.string != NULL)
254     return &st->null;
255 
256   /* Allocate memory for the new string and its associated information.  */
257   newstr = newstring (st, str, len);
258   if (newstr == NULL)
259     return NULL;
260 
261   /* Search in the array for the place to insert the string.  If there
262      is no string with matching prefix and no string with matching
263      leading substring, create a new entry.  */
264   sep = searchstring (&st->root, newstr);
265   if (*sep != newstr)
266     {
267       /* This is not the same entry.  This means we have a prefix match.  */
268       if ((*sep)->len > newstr->len)
269 	{
270 	  struct Ebl_WStrent *subs;
271 
272 	  /* Check whether we already know this string.  */
273 	  for (subs = (*sep)->next; subs != NULL; subs = subs->next)
274 	    if (subs->len == newstr->len)
275 	      {
276 		/* We have an exact match with a substring.  Free the memory
277 		   we allocated.  */
278 		st->left += st->backp - (char *) newstr;
279 		st->backp = (char *) newstr;
280 
281 		return subs;
282 	      }
283 
284 	  /* We have a new substring.  This means we don't need the reverse
285 	     string of this entry anymore.  */
286 	  st->backp -= newstr->len;
287 	  st->left += newstr->len;
288 
289 	  newstr->next = (*sep)->next;
290 	  (*sep)->next = newstr;
291 	}
292       else if ((*sep)->len != newstr->len)
293 	{
294 	  /* When we get here it means that the string we are about to
295 	     add has a common prefix with a string we already have but
296 	     it is longer.  In this case we have to put it first.  */
297 	  st->total += newstr->len - (*sep)->len;
298 	  newstr->next = *sep;
299 	  newstr->left = (*sep)->left;
300 	  newstr->right = (*sep)->right;
301 	  *sep = newstr;
302 	}
303       else
304 	{
305 	  /* We have an exact match.  Free the memory we allocated.  */
306 	  st->left += st->backp - (char *) newstr;
307 	  st->backp = (char *) newstr;
308 
309 	  newstr = *sep;
310 	}
311     }
312   else
313     st->total += newstr->len;
314 
315   return newstr;
316 }
317 
318 
319 static void
copystrings(struct Ebl_WStrent * nodep,wchar_t ** freep,size_t * offsetp)320 copystrings (struct Ebl_WStrent *nodep, wchar_t **freep, size_t *offsetp)
321 {
322   struct Ebl_WStrent *subs;
323 
324   if (nodep->left != NULL)
325     copystrings (nodep->left, freep, offsetp);
326 
327   /* Process the current node.  */
328   nodep->offset = *offsetp;
329   *freep = wmempcpy (*freep, nodep->string, nodep->len);
330   *offsetp += nodep->len * sizeof (wchar_t);
331 
332   for (subs = nodep->next; subs != NULL; subs = subs->next)
333     {
334       assert (subs->len < nodep->len);
335       subs->offset = nodep->offset + nodep->len - subs->len;
336       assert (subs->offset != 0 || subs->string[0] == '\0');
337     }
338 
339   if (nodep->right != NULL)
340     copystrings (nodep->right, freep, offsetp);
341 }
342 
343 
344 void
ebl_wstrtabfinalize(struct Ebl_WStrtab * st,Elf_Data * data)345 ebl_wstrtabfinalize (struct Ebl_WStrtab *st, Elf_Data *data)
346 {
347   size_t copylen;
348   wchar_t *endp;
349   size_t nulllen = st->nullstr ? 1 : 0;
350 
351   /* Fill in the information.  */
352   data->d_buf = malloc ((st->total + nulllen) * sizeof (wchar_t));
353   if (data->d_buf == NULL)
354     abort ();
355 
356   /* The first byte must always be zero if we created the table with a
357      null string.  */
358   if (st->nullstr)
359     *((wchar_t *) data->d_buf) = L'\0';
360 
361   data->d_type = ELF_T_BYTE;
362   data->d_size = st->total + nulllen;
363   data->d_off = 0;
364   data->d_align = 1;
365   data->d_version = EV_CURRENT;
366 
367   /* Now run through the tree and add all the string while also updating
368      the offset members of the elfstrent records.  */
369   endp = (wchar_t *) data->d_buf + nulllen;
370   copylen = sizeof (wchar_t) * nulllen;
371   copystrings (st->root, &endp, &copylen);
372   assert (copylen == (st->total + nulllen) * sizeof (wchar_t));
373 }
374 
375 
376 size_t
ebl_wstrtaboffset(struct Ebl_WStrent * se)377 ebl_wstrtaboffset (struct Ebl_WStrent *se)
378 {
379   return se->offset;
380 }
381