libelf_ar.c revision 1.2
1/* $NetBSD: libelf_ar.c,v 1.2 2014/03/09 16:58:04 christos Exp $ */ 2 3/*- 4 * Copyright (c) 2006,2008,2010 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 <ctype.h> 37#include <libelf.h> 38#include <stdlib.h> 39#include <string.h> 40 41#include "_libelf.h" 42#include "_libelf_ar.h" 43 44__RCSID("$NetBSD: libelf_ar.c,v 1.2 2014/03/09 16:58:04 christos Exp $"); 45ELFTC_VCSID("Id: libelf_ar.c 2225 2011-11-26 18:55:54Z jkoshy "); 46 47#define LIBELF_NALLOC_SIZE 16 48 49/* 50 * `ar' archive handling. 51 * 52 * `ar' archives start with signature `ARMAG'. Each archive member is 53 * preceded by a header containing meta-data for the member. This 54 * header is described in <ar.h> (struct ar_hdr). The header always 55 * starts on an even address. File data is padded with "\n" 56 * characters to keep this invariant. 57 * 58 * Special considerations for `ar' archives: 59 * 60 * There are two variants of the `ar' archive format: traditional BSD 61 * and SVR4. These differ in the way long file names are treated, and 62 * in the layout of the archive symbol table. 63 * 64 * The `ar' header only has space for a 16 character file name. 65 * 66 * In the SVR4 format, file names are terminated with a '/', so this 67 * effectively leaves 15 characters for the actual file name. Longer 68 * file names stored in a separate 'string table' and referenced 69 * indirectly from the name field. The string table itself appears as 70 * an archive member with name "// ". An `indirect' file name in an 71 * `ar' header matches the pattern "/[0-9]*". The digits form a 72 * decimal number that corresponds to a byte offset into the string 73 * table where the actual file name of the object starts. Strings in 74 * the string table are padded to start on even addresses. 75 * 76 * In the BSD format, file names can be upto 16 characters. File 77 * names shorter than 16 characters are padded to 16 characters using 78 * (ASCII) space characters. File names with embedded spaces and file 79 * names longer than 16 characters are stored immediately after the 80 * archive header and the name field set to a special indirect name 81 * matching the pattern "#1/[0-9]+". The digits form a decimal number 82 * that corresponds to the actual length of the file name following 83 * the archive header. The content of the archive member immediately 84 * follows the file name, and the size field of the archive member 85 * holds the sum of the sizes of the member and of the appended file 86 * name. 87 * 88 * Archives may also have a symbol table (see ranlib(1)), mapping 89 * program symbols to object files inside the archive. 90 * 91 * In the SVR4 format, a symbol table uses a file name of "/ " in its 92 * archive header. The symbol table is structured as: 93 * - a 4-byte count of entries stored as a binary value, MSB first 94 * - 'n' 4-byte offsets, stored as binary values, MSB first 95 * - 'n' NUL-terminated strings, for ELF symbol names, stored unpadded. 96 * 97 * In the BSD format, the symbol table uses a file name of "__.SYMDEF". 98 * It is structured as two parts: 99 * - The first part is an array of "ranlib" structures preceded by 100 * the size of the array in bytes. Each "ranlib" structure 101 * describes one symbol. Each structure contains an offset into 102 * the string table for the symbol name, and a file offset into the 103 * archive for the member defining the symbol. 104 * - The second part is a string table containing NUL-terminated 105 * strings, preceded by the size of the string table in bytes. 106 * 107 * If the symbol table and string table are is present in an archive 108 * they must be the very first objects and in that order. 109 */ 110 111 112/* 113 * Retrieve an archive header descriptor. 114 */ 115 116Elf_Arhdr * 117_libelf_ar_gethdr(Elf *e) 118{ 119 Elf *parent; 120 char *namelen; 121 Elf_Arhdr *eh; 122 size_t n, nlen; 123 struct ar_hdr *arh; 124 125 if ((parent = e->e_parent) == NULL) { 126 LIBELF_SET_ERROR(ARGUMENT, 0); 127 return (NULL); 128 } 129 130 assert((e->e_flags & LIBELF_F_AR_HEADER) == 0); 131 132 arh = (struct ar_hdr *) (uintptr_t) e->e_hdr.e_rawhdr; 133 134 assert((uintptr_t) arh >= (uintptr_t) parent->e_rawfile + SARMAG); 135 assert((uintptr_t) arh <= (uintptr_t) parent->e_rawfile + 136 parent->e_rawsize - sizeof(struct ar_hdr)); 137 138 if ((eh = malloc(sizeof(Elf_Arhdr))) == NULL) { 139 LIBELF_SET_ERROR(RESOURCE, 0); 140 return (NULL); 141 } 142 143 e->e_hdr.e_arhdr = eh; 144 e->e_flags |= LIBELF_F_AR_HEADER; 145 146 eh->ar_name = eh->ar_rawname = NULL; 147 148 if ((eh->ar_name = _libelf_ar_get_translated_name(arh, parent)) == 149 NULL) 150 goto error; 151 152 if (_libelf_ar_get_number(arh->ar_uid, sizeof(arh->ar_uid), 10, 153 &n) == 0) 154 goto error; 155 eh->ar_uid = (uid_t) n; 156 157 if (_libelf_ar_get_number(arh->ar_gid, sizeof(arh->ar_gid), 10, 158 &n) == 0) 159 goto error; 160 eh->ar_gid = (gid_t) n; 161 162 if (_libelf_ar_get_number(arh->ar_mode, sizeof(arh->ar_mode), 8, 163 &n) == 0) 164 goto error; 165 eh->ar_mode = (mode_t) n; 166 167 if (_libelf_ar_get_number(arh->ar_size, sizeof(arh->ar_size), 10, 168 &n) == 0) 169 goto error; 170 171 /* 172 * Get the true size of the member if extended naming is being used. 173 */ 174 if (IS_EXTENDED_BSD_NAME(arh->ar_name)) { 175 namelen = arh->ar_name + 176 LIBELF_AR_BSD_EXTENDED_NAME_PREFIX_SIZE; 177 if (_libelf_ar_get_number(namelen, sizeof(arh->ar_name) - 178 LIBELF_AR_BSD_EXTENDED_NAME_PREFIX_SIZE, 10, &nlen) == 0) 179 goto error; 180 n -= nlen; 181 } 182 183 eh->ar_size = n; 184 185 if ((eh->ar_rawname = _libelf_ar_get_raw_name(arh)) == NULL) 186 goto error; 187 188 eh->ar_flags = 0; 189 190 return (eh); 191 192 error: 193 if (eh) { 194 if (eh->ar_name) 195 free(eh->ar_name); 196 if (eh->ar_rawname) 197 free(eh->ar_rawname); 198 free(eh); 199 } 200 201 e->e_flags &= ~LIBELF_F_AR_HEADER; 202 e->e_hdr.e_rawhdr = (char *) arh; 203 204 return (NULL); 205} 206 207Elf * 208_libelf_ar_open_member(int fd, Elf_Cmd c, Elf *elf) 209{ 210 Elf *e; 211 char *member, *namelen; 212 size_t nsz, sz; 213 off_t next; 214 struct ar_hdr *arh; 215 216 assert(elf->e_kind == ELF_K_AR); 217 218 next = elf->e_u.e_ar.e_next; 219 220 /* 221 * `next' is only set to zero by elf_next() when the last 222 * member of an archive is processed. 223 */ 224 if (next == (off_t) 0) 225 return (NULL); 226 227 assert((next & 1) == 0); 228 229 arh = (struct ar_hdr *) (elf->e_rawfile + next); 230 231 /* 232 * Retrieve the size of the member. 233 */ 234 if (_libelf_ar_get_number(arh->ar_size, sizeof(arh->ar_size), 10, 235 &sz) == 0) { 236 LIBELF_SET_ERROR(ARCHIVE, 0); 237 return (NULL); 238 } 239 240 /* 241 * Adjust the size field for members in BSD archives using 242 * extended naming. 243 */ 244 if (IS_EXTENDED_BSD_NAME(arh->ar_name)) { 245 namelen = arh->ar_name + 246 LIBELF_AR_BSD_EXTENDED_NAME_PREFIX_SIZE; 247 if (_libelf_ar_get_number(namelen, sizeof(arh->ar_name) - 248 LIBELF_AR_BSD_EXTENDED_NAME_PREFIX_SIZE, 10, &nsz) == 0) { 249 LIBELF_SET_ERROR(ARCHIVE, 0); 250 return (NULL); 251 } 252 253 member = (char *) (arh + 1) + nsz; 254 sz -= nsz; 255 } else 256 member = (char *) (arh + 1); 257 258 259 if ((e = elf_memory((char *) member, sz)) == NULL) 260 return (NULL); 261 262 e->e_fd = fd; 263 e->e_cmd = c; 264 e->e_hdr.e_rawhdr = (char *) arh; 265 266 elf->e_u.e_ar.e_nchildren++; 267 e->e_parent = elf; 268 269 return (e); 270} 271 272/* 273 * A BSD-style ar(1) symbol table has the following layout: 274 * 275 * - A count of bytes used by the following array of 'ranlib' 276 * structures, stored as a 'long'. 277 * - An array of 'ranlib' structures. Each array element is 278 * two 'long's in size. 279 * - A count of bytes used for the following symbol table. 280 * - The symbol table itself. 281 */ 282 283/* 284 * A helper macro to read in a 'long' value from the archive. We use 285 * memcpy() since the source pointer may be misaligned with respect to 286 * the natural alignment for a C 'long'. 287 */ 288#define GET_LONG(P, V)do { \ 289 memcpy(&(V), (P), sizeof(long)); \ 290 (P) += sizeof(long); \ 291 } while (/*CONSTCOND*/0) 292 293Elf_Arsym * 294_libelf_ar_process_bsd_symtab(Elf *e, size_t *count) 295{ 296 Elf_Arsym *symtab, *sym; 297 unsigned char *end, *p, *p0, *s, *s0; 298 const unsigned int entrysize = 2 * sizeof(long); 299 long arraysize, fileoffset, n, nentries, stroffset, strtabsize; 300 301 assert(e != NULL); 302 assert(count != NULL); 303 assert(e->e_u.e_ar.e_symtab == NULL); 304 305 symtab = NULL; 306 307 /* 308 * The BSD symbol table always contains the count fields even 309 * if there are no entries in it. 310 */ 311 if (e->e_u.e_ar.e_rawsymtabsz < 2 * sizeof(long)) 312 goto symtaberror; 313 314 p = p0 = (unsigned char *) e->e_u.e_ar.e_rawsymtab; 315 end = p0 + e->e_u.e_ar.e_rawsymtabsz; 316 317 /* 318 * Retrieve the size of the array of ranlib descriptors and 319 * check it for validity. 320 */ 321 GET_LONG(p, arraysize); 322 323 if (p0 + arraysize >= end || (arraysize % entrysize != 0)) 324 goto symtaberror; 325 326 /* 327 * Check the value of the string table size. 328 */ 329 s = p + arraysize; 330 GET_LONG(s, strtabsize); 331 332 s0 = s; /* Start of string table. */ 333 if (s0 + strtabsize > end) 334 goto symtaberror; 335 336 nentries = arraysize / entrysize; 337 338 /* 339 * Allocate space for the returned Elf_Arsym array. 340 */ 341 if ((symtab = malloc(sizeof(Elf_Arsym) * (nentries + 1))) == NULL) { 342 LIBELF_SET_ERROR(RESOURCE, 0); 343 return (NULL); 344 } 345 346 /* Read in symbol table entries. */ 347 for (n = 0, sym = symtab; n < nentries; n++, sym++) { 348 GET_LONG(p, stroffset); 349 GET_LONG(p, fileoffset); 350 351 s = s0 + stroffset; 352 353 if (s >= end) 354 goto symtaberror; 355 356 sym->as_off = fileoffset; 357 sym->as_hash = elf_hash((char *) s); 358 sym->as_name = (char *) s; 359 } 360 361 /* Fill up the sentinel entry. */ 362 sym->as_name = NULL; 363 sym->as_hash = ~0UL; 364 sym->as_off = (off_t) 0; 365 366 /* Remember the processed symbol table. */ 367 e->e_u.e_ar.e_symtab = symtab; 368 369 *count = e->e_u.e_ar.e_symtabsz = nentries + 1; 370 371 return (symtab); 372 373symtaberror: 374 if (symtab) 375 free(symtab); 376 LIBELF_SET_ERROR(ARCHIVE, 0); 377 return (NULL); 378} 379 380/* 381 * An SVR4-style ar(1) symbol table has the following layout: 382 * 383 * - The first 4 bytes are a binary count of the number of entries in the 384 * symbol table, stored MSB-first. 385 * - Then there are 'n' 4-byte binary offsets, also stored MSB first. 386 * - Following this, there are 'n' null-terminated strings. 387 */ 388 389#define GET_WORD(P, V) do { \ 390 (V) = 0; \ 391 (V) = (P)[0]; (V) <<= 8; \ 392 (V) += (P)[1]; (V) <<= 8; \ 393 (V) += (P)[2]; (V) <<= 8; \ 394 (V) += (P)[3]; \ 395 } while (0) 396 397#define INTSZ 4 398 399 400Elf_Arsym * 401_libelf_ar_process_svr4_symtab(Elf *e, size_t *count) 402{ 403 size_t n, nentries, off; 404 Elf_Arsym *symtab, *sym; 405 unsigned char *p, *s, *end; 406 407 assert(e != NULL); 408 assert(count != NULL); 409 assert(e->e_u.e_ar.e_symtab == NULL); 410 411 symtab = NULL; 412 413 if (e->e_u.e_ar.e_rawsymtabsz < INTSZ) 414 goto symtaberror; 415 416 p = (unsigned char *) e->e_u.e_ar.e_rawsymtab; 417 end = p + e->e_u.e_ar.e_rawsymtabsz; 418 419 GET_WORD(p, nentries); 420 p += INTSZ; 421 422 if (nentries == 0 || p + nentries * INTSZ >= end) 423 goto symtaberror; 424 425 /* Allocate space for a nentries + a sentinel. */ 426 if ((symtab = malloc(sizeof(Elf_Arsym) * (nentries+1))) == NULL) { 427 LIBELF_SET_ERROR(RESOURCE, 0); 428 return (NULL); 429 } 430 431 s = p + (nentries * INTSZ); /* start of the string table. */ 432 433 for (n = nentries, sym = symtab; n > 0; n--) { 434 435 if (s >= end) 436 goto symtaberror; 437 438 off = 0; 439 440 GET_WORD(p, off); 441 442 sym->as_off = off; 443 sym->as_hash = elf_hash((char *) s); 444 sym->as_name = (char *) s; 445 446 p += INTSZ; 447 sym++; 448 449 for (; s < end && *s++ != '\0';) /* skip to next string */ 450 ; 451 } 452 453 /* Fill up the sentinel entry. */ 454 sym->as_name = NULL; 455 sym->as_hash = ~0UL; 456 sym->as_off = (off_t) 0; 457 458 *count = e->e_u.e_ar.e_symtabsz = nentries + 1; 459 e->e_u.e_ar.e_symtab = symtab; 460 461 return (symtab); 462 463symtaberror: 464 if (symtab) 465 free(symtab); 466 LIBELF_SET_ERROR(ARCHIVE, 0); 467 return (NULL); 468} 469