2 * Copyright (c) 2006 Joseph Koshy
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS `AS IS' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
39 #define LIBELF_NALLOC_SIZE 16
42 * `ar' archive handling.
44 * `ar' archives start with signature `ARMAG'. Each archive member is
45 * preceded by a header containing meta-data for the member. This
46 * header is described in <ar.h> (struct ar_hdr). The header always
47 * starts on an even address. File data is padded with "\n"
48 * characters to keep this invariant.
50 * Special considerations for `ar' archives:
52 * The `ar' header only has space for a 16 character file name. File
53 * names are terminated with a '/', so this effectively leaves 15
54 * characters for the actual file name. In order to accomodate longer
55 * file names, names may be stored in a separate 'string table' and
56 * referenced indirectly by a member header. The string table itself
57 * appears as an archive member with name "// ". An indirect file name
58 * in an `ar' header matches the pattern "/[0-9]*". The digits form a
59 * decimal number that corresponds to a byte offset into the string
60 * table where the actual file name of the object starts. Strings in
61 * the string table are padded to start on even addresses.
63 * Archives may also have a symbol table (see ranlib(1)), mapping
64 * program symbols to object files inside the archive. A symbol table
65 * uses a file name of "/ " in its archive header. The symbol table
67 * - a 4-byte count of entries stored as a binary value, MSB first
68 * - 'n' 4-byte offsets, stored as binary values, MSB first
69 * - 'n' NUL-terminated strings, for ELF symbol names, stored unpadded.
71 * If the symbol table and string table are is present in an archive
72 * they must be the very first objects and in that order.
76 * Convert a string bounded by `start' and `start+sz' (exclusive) to a
77 * number in the specified base.
80 _libelf_ar_get_number(char *s, size_t sz, int base, size_t *ret)
90 /* skip leading blanks */
91 for (;s < e && (c = *s) == ' '; s++)
98 if (c < '0' || c > '9')
101 if (v >= base) /* Illegal digit. */
113 * Retrieve a string from a name field. If `rawname' is set, leave
114 * ar(1) control characters in.
117 _libelf_ar_get_string(char *buf, size_t bufsize, int rawname)
122 /* Skip back over trailing blanks. */
123 for (q = buf + bufsize - 1; q > buf && *q == ' '; --q)
126 if (rawname == 0 && *q == '/')
132 sz = q - buf + 2; /* Space for a trailing NUL. */
133 if ((r = malloc(sz)) == NULL) {
134 LIBELF_SET_ERROR(RESOURCE, 0);
138 (void) strncpy(r, buf, sz);
145 * Retrieve the full name of the archive member.
148 _libelf_ar_get_name(char *buf, size_t bufsize, Elf *e)
154 assert(e->e_kind == ELF_K_AR);
158 * The value in field ar_name is a decimal offset into
159 * the archive string table where the actual name
162 if (_libelf_ar_get_number(buf + 1, bufsize - 1, 10,
164 LIBELF_SET_ERROR(ARCHIVE, 0);
168 if (offset > e->e_u.e_ar.e_rawstrtabsz) {
169 LIBELF_SET_ERROR(ARCHIVE, 0);
173 s = q = e->e_u.e_ar.e_rawstrtab + offset;
174 r = e->e_u.e_ar.e_rawstrtab + e->e_u.e_ar.e_rawstrtabsz;
176 for (s = q; s < r && *s != '/'; s++)
178 len = s - q + 1; /* space for the trailing NUL */
180 if ((s = malloc(len)) == NULL) {
181 LIBELF_SET_ERROR(RESOURCE, 0);
185 (void) strncpy(s, q, len);
194 return (_libelf_ar_get_string(buf, bufsize, 0));
199 _libelf_ar_gethdr(Elf *e)
206 if ((parent = e->e_parent) == NULL) {
207 LIBELF_SET_ERROR(ARGUMENT, 0);
211 arh = (struct ar_hdr *) ((uintptr_t) e->e_rawfile - sizeof(struct ar_hdr));
213 assert((uintptr_t) arh >= (uintptr_t) parent->e_rawfile + SARMAG);
214 assert((uintptr_t) arh <= (uintptr_t) parent->e_rawfile + parent->e_rawsize -
215 sizeof(struct ar_hdr));
217 if ((eh = malloc(sizeof(Elf_Arhdr))) == NULL) {
218 LIBELF_SET_ERROR(RESOURCE, 0);
223 eh->ar_name = eh->ar_rawname = NULL;
225 if ((eh->ar_name = _libelf_ar_get_name(arh->ar_name, sizeof(arh->ar_name),
229 if (_libelf_ar_get_number(arh->ar_uid, sizeof(arh->ar_uid), 10, &n) == 0)
231 eh->ar_uid = (uid_t) n;
233 if (_libelf_ar_get_number(arh->ar_gid, sizeof(arh->ar_gid), 10, &n) == 0)
235 eh->ar_gid = (gid_t) n;
237 if (_libelf_ar_get_number(arh->ar_mode, sizeof(arh->ar_mode), 8, &n) == 0)
239 eh->ar_mode = (mode_t) n;
241 if (_libelf_ar_get_number(arh->ar_size, sizeof(arh->ar_size), 10, &n) == 0)
245 if ((eh->ar_rawname = _libelf_ar_get_string(arh->ar_name,
246 sizeof(arh->ar_name), 1)) == NULL)
256 free(eh->ar_rawname);
265 _libelf_ar_open_member(int fd, Elf_Cmd c, Elf *elf)
272 assert(elf->e_kind == ELF_K_AR);
274 next = elf->e_u.e_ar.e_next;
277 * `next' is only set to zero by elf_next() when the last
278 * member of an archive is processed.
280 if (next == (off_t) 0)
283 assert((next & 1) == 0);
285 arh = (struct ar_hdr *) (elf->e_rawfile + next);
287 if (_libelf_ar_get_number(arh->ar_size, sizeof(arh->ar_size), 10, &sz) == 0) {
288 LIBELF_SET_ERROR(ARCHIVE, 0);
294 arh++; /* skip over archive member header */
296 if ((e = elf_memory((char *) arh, sz)) == NULL)
302 elf->e_u.e_ar.e_nchildren++;
309 _libelf_ar_open(Elf *e)
316 e->e_kind = ELF_K_AR;
317 e->e_u.e_ar.e_nchildren = 0;
318 e->e_u.e_ar.e_next = (off_t) -1;
321 * Look for special members.
324 s = e->e_rawfile + SARMAG;
325 end = e->e_rawfile + e->e_rawsize;
327 assert(e->e_rawsize > 0);
330 * Look for magic names "/ " and "// " in the first two entries
333 for (i = 0; i < 2; i++) {
335 if (s + sizeof(arh) > end) {
336 LIBELF_SET_ERROR(ARCHIVE, 0);
340 (void) memcpy(&arh, s, sizeof(arh));
342 if (arh.ar_fmag[0] != '`' || arh.ar_fmag[1] != '\n') {
343 LIBELF_SET_ERROR(ARCHIVE, 0);
347 if (arh.ar_name[0] != '/') /* not a special symbol */
350 if (_libelf_ar_get_number(arh.ar_size, sizeof(arh.ar_size), 10, &sz) == 0) {
351 LIBELF_SET_ERROR(ARCHIVE, 0);
359 if (arh.ar_name[1] == ' ') { /* "/ " => symbol table */
361 e->e_u.e_ar.e_rawsymtab = s;
362 e->e_u.e_ar.e_rawsymtabsz = sz;
364 } else if (arh.ar_name[1] == '/' && arh.ar_name[2] == ' ') {
366 /* "// " => string table for long file names */
367 e->e_u.e_ar.e_rawstrtab = s;
368 e->e_u.e_ar.e_rawstrtabsz = sz;
371 sz = LIBELF_ADJUST_AR_SIZE(sz);
376 e->e_u.e_ar.e_next = (off_t) (s - e->e_rawfile);
382 * An ar(1) symbol table has the following layout:
384 * The first 4 bytes are a binary count of the number of entries in the
385 * symbol table, stored MSB-first.
387 * Then there are 'n' 4-byte binary offsets, also stored MSB first.
389 * Following this, there are 'n' null-terminated strings.
392 #define GET_WORD(P, V) do { \
394 (V) = (P)[0]; (V) <<= 8; \
395 (V) += (P)[1]; (V) <<= 8; \
396 (V) += (P)[2]; (V) <<= 8; \
403 _libelf_ar_process_symtab(Elf *e, size_t *count)
405 size_t n, nentries, off;
406 Elf_Arsym *symtab, *sym;
407 unsigned char *p, *s, *end;
410 assert(count != NULL);
412 if (e->e_u.e_ar.e_rawsymtabsz < INTSZ) {
413 LIBELF_SET_ERROR(ARCHIVE, 0);
417 p = (unsigned char *) e->e_u.e_ar.e_rawsymtab;
418 end = p + e->e_u.e_ar.e_rawsymtabsz;
420 GET_WORD(p, nentries);
423 if (nentries == 0 || p + nentries * INTSZ >= end) {
424 LIBELF_SET_ERROR(ARCHIVE, 0);
428 /* Allocate space for a nentries + a sentinel. */
429 if ((symtab = malloc(sizeof(Elf_Arsym) * (nentries+1))) == NULL) {
430 LIBELF_SET_ERROR(RESOURCE, 0);
434 s = p + (nentries * INTSZ); /* start of the string table. */
436 for (n = nentries, sym = symtab; n > 0; n--) {
442 sym->as_hash = elf_hash(s);
448 for (; s < end && *s++ != '\0';) /* skip to next string */
451 LIBELF_SET_ERROR(ARCHIVE, 0);
457 /* Fill up the sentinel entry. */
460 sym->as_off = (off_t) 0;
462 *count = e->e_u.e_ar.e_symtabsz = nentries + 1;
463 e->e_u.e_ar.e_symtab = symtab;