1 /* $NetBSD: libelf_ar_util.c,v 1.2 2014/03/09 16:58:04 christos Exp $ */
2
3 /*-
4 * Copyright (c) 2006,2009,2010 Joseph Koshy
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS `AS IS' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #if HAVE_NBTOOL_CONFIG_H
30 # include "nbtool_config.h"
31 #endif
32
33 #include <sys/cdefs.h>
34
35 #include <assert.h>
36 #include <libelf.h>
37 #include <stdlib.h>
38 #include <string.h>
39
40 #include "_libelf.h"
41 #include "_libelf_ar.h"
42
43 __RCSID("$NetBSD: libelf_ar_util.c,v 1.2 2014/03/09 16:58:04 christos Exp $");
44 ELFTC_VCSID("Id: libelf_ar_util.c 2365 2011-12-29 04:36:44Z jkoshy ");
45
46 /*
47 * Convert a string bounded by `start' and `start+sz' (exclusive) to a
48 * number in the specified base.
49 */
50 int
_libelf_ar_get_number(const char * s,size_t sz,int base,size_t * ret)51 _libelf_ar_get_number(const char *s, size_t sz, int base, size_t *ret)
52 {
53 int c, v;
54 size_t r;
55 const char *e;
56
57 assert(base <= 10);
58
59 e = s + sz;
60
61 /* skip leading blanks */
62 for (;s < e && (c = *s) == ' '; s++)
63 ;
64
65 r = 0L;
66 for (;s < e; s++) {
67 if ((c = *s) == ' ')
68 break;
69 if (c < '0' || c > '9')
70 return (0);
71 v = c - '0';
72 if (v >= base) /* Illegal digit. */
73 break;
74 r *= base;
75 r += v;
76 }
77
78 *ret = r;
79
80 return (1);
81 }
82
83 /*
84 * Return the translated name for an archive member.
85 */
86 char *
_libelf_ar_get_translated_name(const struct ar_hdr * arh,Elf * ar)87 _libelf_ar_get_translated_name(const struct ar_hdr *arh, Elf *ar)
88 {
89 char c, *s;
90 size_t len, offset;
91 const char *buf, *p, *q, *r;
92 const size_t bufsize = sizeof(arh->ar_name);
93
94 assert(arh != NULL);
95 assert(ar->e_kind == ELF_K_AR);
96 assert((const char *) arh >= ar->e_rawfile &&
97 (const char *) arh < ar->e_rawfile + ar->e_rawsize);
98
99 buf = arh->ar_name;
100
101 /*
102 * Check for extended naming.
103 *
104 * If the name matches the pattern "^/[0-9]+", it is an
105 * SVR4-style extended name. If the name matches the pattern
106 * "#1/[0-9]+", the entry uses BSD style extended naming.
107 */
108 if (buf[0] == '/' && (c = buf[1]) >= '0' && c <= '9') {
109 /*
110 * The value in field ar_name is a decimal offset into
111 * the archive string table where the actual name
112 * resides.
113 */
114 if (_libelf_ar_get_number(buf + 1, bufsize - 1, 10,
115 &offset) == 0) {
116 LIBELF_SET_ERROR(ARCHIVE, 0);
117 return (NULL);
118 }
119
120 if (offset > ar->e_u.e_ar.e_rawstrtabsz) {
121 LIBELF_SET_ERROR(ARCHIVE, 0);
122 return (NULL);
123 }
124
125 p = q = ar->e_u.e_ar.e_rawstrtab + offset;
126 r = ar->e_u.e_ar.e_rawstrtab + ar->e_u.e_ar.e_rawstrtabsz;
127
128 for (; p < r && *p != '/'; p++)
129 ;
130 len = p - q + 1; /* space for the trailing NUL */
131
132 if ((s = malloc(len)) == NULL) {
133 LIBELF_SET_ERROR(RESOURCE, 0);
134 return (NULL);
135 }
136
137 (void) strncpy(s, q, len - 1);
138 s[len - 1] = '\0';
139
140 return (s);
141 } else if (IS_EXTENDED_BSD_NAME(buf)) {
142 r = buf + LIBELF_AR_BSD_EXTENDED_NAME_PREFIX_SIZE;
143
144 if (_libelf_ar_get_number(r, bufsize -
145 LIBELF_AR_BSD_EXTENDED_NAME_PREFIX_SIZE, 10,
146 &len) == 0) {
147 LIBELF_SET_ERROR(ARCHIVE, 0);
148 return (NULL);
149 }
150
151 /*
152 * Allocate space for the file name plus a
153 * trailing NUL.
154 */
155 if ((s = malloc(len + 1)) == NULL) {
156 LIBELF_SET_ERROR(RESOURCE, 0);
157 return (NULL);
158 }
159
160 /*
161 * The file name follows the archive header.
162 */
163 q = (const char *) (arh + 1);
164
165 (void) strncpy(s, q, len);
166 s[len] = '\0';
167
168 return (s);
169 }
170
171 /*
172 * A 'normal' name.
173 *
174 * Skip back over trailing blanks from the end of the field.
175 * In the SVR4 format, a '/' is used as a terminator for
176 * non-special names.
177 */
178 for (q = buf + bufsize - 1; q >= buf && *q == ' '; --q)
179 ;
180
181 if (q >= buf) {
182 if (*q == '/') {
183 /*
184 * SVR4 style names: ignore the trailing
185 * character '/', but only if the name is not
186 * one of the special names "/" and "//".
187 */
188 if (q > buf + 1 ||
189 (q == (buf + 1) && *buf != '/'))
190 q--;
191 }
192
193 len = q - buf + 2; /* Add space for a trailing NUL. */
194 } else {
195 /* The buffer only had blanks. */
196 buf = "";
197 len = 1;
198 }
199
200 if ((s = malloc(len)) == NULL) {
201 LIBELF_SET_ERROR(RESOURCE, 0);
202 return (NULL);
203 }
204
205 (void) strncpy(s, buf, len - 1);
206 s[len - 1] = '\0';
207
208 return (s);
209 }
210
211 /*
212 * Return the raw name for an archive member, inclusive of any
213 * formatting characters.
214 */
215 char *
_libelf_ar_get_raw_name(const struct ar_hdr * arh)216 _libelf_ar_get_raw_name(const struct ar_hdr *arh)
217 {
218 char *rawname;
219 const size_t namesz = sizeof(arh->ar_name);
220
221 if ((rawname = malloc(namesz + 1)) == NULL) {
222 LIBELF_SET_ERROR(RESOURCE, 0);
223 return (NULL);
224 }
225
226 (void) strncpy(rawname, arh->ar_name, namesz);
227 rawname[namesz] = '\0';
228 return (rawname);
229 }
230
231 /*
232 * Open an 'ar' archive.
233 */
234 Elf *
_libelf_ar_open(Elf * e,int reporterror)235 _libelf_ar_open(Elf *e, int reporterror)
236 {
237 size_t sz;
238 int scanahead;
239 char *s, *end;
240 struct ar_hdr arh;
241
242 _libelf_init_elf(e, ELF_K_AR);
243
244 e->e_u.e_ar.e_nchildren = 0;
245 e->e_u.e_ar.e_next = (off_t) -1;
246
247 /*
248 * Look for special members.
249 */
250
251 s = e->e_rawfile + SARMAG;
252 end = e->e_rawfile + e->e_rawsize;
253
254 assert(e->e_rawsize > 0);
255
256 /*
257 * We use heuristics to determine the flavor of the archive we
258 * are examining.
259 *
260 * SVR4 flavor archives use the name "/ " and "// " for
261 * special members.
262 *
263 * In BSD flavor archives the symbol table, if present, is the
264 * first archive with name "__.SYMDEF".
265 */
266
267 #define READ_AR_HEADER(S, ARH, SZ, END) \
268 do { \
269 if ((S) + sizeof((ARH)) > (END)) \
270 goto error; \
271 (void) memcpy(&(ARH), (S), sizeof((ARH))); \
272 if ((ARH).ar_fmag[0] != '`' || (ARH).ar_fmag[1] != '\n') \
273 goto error; \
274 if (_libelf_ar_get_number((ARH).ar_size, \
275 sizeof((ARH).ar_size), 10, &(SZ)) == 0) \
276 goto error; \
277 } while (0)
278
279 READ_AR_HEADER(s, arh, sz, end);
280
281 /*
282 * Handle special archive members for the SVR4 format.
283 */
284 if (arh.ar_name[0] == '/') {
285
286 assert(sz > 0);
287
288 e->e_flags |= LIBELF_F_AR_VARIANT_SVR4;
289
290 scanahead = 0;
291
292 /*
293 * The symbol table (file name "/ ") always comes before the
294 * string table (file name "// ").
295 */
296 if (arh.ar_name[1] == ' ') {
297 /* "/ " => symbol table. */
298 scanahead = 1; /* The string table to follow. */
299
300 s += sizeof(arh);
301 e->e_u.e_ar.e_rawsymtab = s;
302 e->e_u.e_ar.e_rawsymtabsz = sz;
303
304 sz = LIBELF_ADJUST_AR_SIZE(sz);
305 s += sz;
306
307 } else if (arh.ar_name[1] == '/' && arh.ar_name[2] == ' ') {
308 /* "// " => string table for long file names. */
309 s += sizeof(arh);
310 e->e_u.e_ar.e_rawstrtab = s;
311 e->e_u.e_ar.e_rawstrtabsz = sz;
312
313 sz = LIBELF_ADJUST_AR_SIZE(sz);
314 s += sz;
315 }
316
317 /*
318 * If the string table hasn't been seen yet, look for
319 * it in the next member.
320 */
321 if (scanahead) {
322 READ_AR_HEADER(s, arh, sz, end);
323
324 /* "// " => string table for long file names. */
325 if (arh.ar_name[0] == '/' && arh.ar_name[1] == '/' &&
326 arh.ar_name[2] == ' ') {
327
328 s += sizeof(arh);
329
330 e->e_u.e_ar.e_rawstrtab = s;
331 e->e_u.e_ar.e_rawstrtabsz = sz;
332
333 sz = LIBELF_ADJUST_AR_SIZE(sz);
334 s += sz;
335 }
336 }
337 } else if (strncmp(arh.ar_name, LIBELF_AR_BSD_SYMTAB_NAME,
338 sizeof(LIBELF_AR_BSD_SYMTAB_NAME) - 1) == 0) {
339 /*
340 * BSD style archive symbol table.
341 */
342 s += sizeof(arh);
343 e->e_u.e_ar.e_rawsymtab = s;
344 e->e_u.e_ar.e_rawsymtabsz = sz;
345
346 sz = LIBELF_ADJUST_AR_SIZE(sz);
347 s += sz;
348 }
349
350 /*
351 * Update the 'next' offset, so that a subsequent elf_begin()
352 * works as expected.
353 */
354 e->e_u.e_ar.e_next = (off_t) (s - e->e_rawfile);
355
356 return (e);
357
358 error:
359 if (!reporterror) {
360 e->e_kind = ELF_K_NONE;
361 return (e);
362 }
363
364 LIBELF_SET_ERROR(ARCHIVE, 0);
365 return (NULL);
366 }
367