1 /*- 2 * Copyright (c) 2006,2009,2010 Joseph Koshy 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 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. 13 * 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 24 * SUCH DAMAGE. 25 */ 26 27 #include <assert.h> 28 #include <libelf.h> 29 #include <stdlib.h> 30 #include <string.h> 31 32 #include "_libelf.h" 33 #include "_libelf_ar.h" 34 35 ELFTC_VCSID("$Id: libelf_ar_util.c 3174 2015-03-27 17:13:41Z emaste $"); 36 37 /* 38 * Convert a string bounded by `start' and `start+sz' (exclusive) to a 39 * number in the specified base. 40 */ 41 int 42 _libelf_ar_get_number(const char *src, size_t sz, unsigned int base, 43 size_t *ret) 44 { 45 size_t r; 46 unsigned int c, v; 47 const unsigned char *e, *s; 48 49 assert(base <= 10); 50 51 s = (const unsigned char *) src; 52 e = s + sz; 53 54 /* skip leading blanks */ 55 for (;s < e && (c = *s) == ' '; s++) 56 ; 57 58 r = 0L; 59 for (;s < e; s++) { 60 if ((c = *s) == ' ') 61 break; 62 if (c < '0' || c > '9') 63 return (0); 64 v = c - '0'; 65 if (v >= base) /* Illegal digit. */ 66 break; 67 r *= base; 68 r += v; 69 } 70 71 *ret = r; 72 73 return (1); 74 } 75 76 /* 77 * Return the translated name for an archive member. 78 */ 79 char * 80 _libelf_ar_get_translated_name(const struct ar_hdr *arh, Elf *ar) 81 { 82 char *s; 83 unsigned char c; 84 size_t len, offset; 85 const unsigned char *buf, *p, *q, *r; 86 const size_t bufsize = sizeof(arh->ar_name); 87 88 assert(arh != NULL); 89 assert(ar->e_kind == ELF_K_AR); 90 assert((const unsigned char *) arh >= ar->e_rawfile && 91 (const unsigned char *) arh < ar->e_rawfile + ar->e_rawsize); 92 93 buf = (const unsigned char *) arh->ar_name; 94 95 /* 96 * Check for extended naming. 97 * 98 * If the name matches the pattern "^/[0-9]+", it is an 99 * SVR4-style extended name. If the name matches the pattern 100 * "#1/[0-9]+", the entry uses BSD style extended naming. 101 */ 102 if (buf[0] == '/' && (c = buf[1]) >= '0' && c <= '9') { 103 /* 104 * The value in field ar_name is a decimal offset into 105 * the archive string table where the actual name 106 * resides. 107 */ 108 if (_libelf_ar_get_number((const char *) (buf + 1), 109 bufsize - 1, 10, &offset) == 0) { 110 LIBELF_SET_ERROR(ARCHIVE, 0); 111 return (NULL); 112 } 113 114 if (offset > ar->e_u.e_ar.e_rawstrtabsz) { 115 LIBELF_SET_ERROR(ARCHIVE, 0); 116 return (NULL); 117 } 118 119 p = q = ar->e_u.e_ar.e_rawstrtab + offset; 120 r = ar->e_u.e_ar.e_rawstrtab + ar->e_u.e_ar.e_rawstrtabsz; 121 122 for (; p < r && *p != '/'; p++) 123 ; 124 len = (size_t) (p - q + 1); /* space for the trailing NUL */ 125 126 if ((s = malloc(len)) == NULL) { 127 LIBELF_SET_ERROR(RESOURCE, 0); 128 return (NULL); 129 } 130 131 (void) strncpy(s, (const char *) q, len - 1); 132 s[len - 1] = '\0'; 133 134 return (s); 135 } else if (IS_EXTENDED_BSD_NAME(buf)) { 136 r = buf + LIBELF_AR_BSD_EXTENDED_NAME_PREFIX_SIZE; 137 138 if (_libelf_ar_get_number((const char *) r, bufsize - 139 LIBELF_AR_BSD_EXTENDED_NAME_PREFIX_SIZE, 10, 140 &len) == 0) { 141 LIBELF_SET_ERROR(ARCHIVE, 0); 142 return (NULL); 143 } 144 145 /* 146 * Allocate space for the file name plus a 147 * trailing NUL. 148 */ 149 if ((s = malloc(len + 1)) == NULL) { 150 LIBELF_SET_ERROR(RESOURCE, 0); 151 return (NULL); 152 } 153 154 /* 155 * The file name follows the archive header. 156 */ 157 q = (const unsigned char *) (arh + 1); 158 159 (void) strncpy(s, (const char *) q, len); 160 s[len] = '\0'; 161 162 return (s); 163 } 164 165 /* 166 * A 'normal' name. 167 * 168 * Skip back over trailing blanks from the end of the field. 169 * In the SVR4 format, a '/' is used as a terminator for 170 * non-special names. 171 */ 172 for (q = buf + bufsize - 1; q >= buf && *q == ' '; --q) 173 ; 174 175 if (q >= buf) { 176 if (*q == '/') { 177 /* 178 * SVR4 style names: ignore the trailing 179 * character '/', but only if the name is not 180 * one of the special names "/" and "//". 181 */ 182 if (q > buf + 1 || 183 (q == (buf + 1) && *buf != '/')) 184 q--; 185 } 186 187 len = (size_t) (q - buf + 2); /* Space for a trailing NUL. */ 188 } else { 189 /* The buffer only had blanks. */ 190 buf = (const unsigned char *) ""; 191 len = 1; 192 } 193 194 if ((s = malloc(len)) == NULL) { 195 LIBELF_SET_ERROR(RESOURCE, 0); 196 return (NULL); 197 } 198 199 (void) strncpy(s, (const char *) buf, len - 1); 200 s[len - 1] = '\0'; 201 202 return (s); 203 } 204 205 /* 206 * Return the raw name for an archive member, inclusive of any 207 * formatting characters. 208 */ 209 char * 210 _libelf_ar_get_raw_name(const struct ar_hdr *arh) 211 { 212 char *rawname; 213 const size_t namesz = sizeof(arh->ar_name); 214 215 if ((rawname = malloc(namesz + 1)) == NULL) { 216 LIBELF_SET_ERROR(RESOURCE, 0); 217 return (NULL); 218 } 219 220 (void) strncpy(rawname, arh->ar_name, namesz); 221 rawname[namesz] = '\0'; 222 return (rawname); 223 } 224 225 /* 226 * Open an 'ar' archive. 227 */ 228 Elf * 229 _libelf_ar_open(Elf *e, int reporterror) 230 { 231 size_t sz; 232 int scanahead; 233 struct ar_hdr arh; 234 unsigned char *s, *end; 235 236 _libelf_init_elf(e, ELF_K_AR); 237 238 e->e_u.e_ar.e_nchildren = 0; 239 e->e_u.e_ar.e_next = (off_t) -1; 240 241 /* 242 * Look for special members. 243 */ 244 245 s = e->e_rawfile + SARMAG; 246 end = e->e_rawfile + e->e_rawsize; 247 248 assert(e->e_rawsize > 0); 249 250 /* 251 * We use heuristics to determine the flavor of the archive we 252 * are examining. 253 * 254 * SVR4 flavor archives use the name "/ " and "// " for 255 * special members. 256 * 257 * In BSD flavor archives the symbol table, if present, is the 258 * first archive with name "__.SYMDEF". 259 */ 260 261 #define READ_AR_HEADER(S, ARH, SZ, END) \ 262 do { \ 263 if ((S) + sizeof((ARH)) > (END)) \ 264 goto error; \ 265 (void) memcpy(&(ARH), (S), sizeof((ARH))); \ 266 if ((ARH).ar_fmag[0] != '`' || (ARH).ar_fmag[1] != '\n') \ 267 goto error; \ 268 if (_libelf_ar_get_number((char *) (ARH).ar_size, \ 269 sizeof((ARH).ar_size), 10, &(SZ)) == 0) \ 270 goto error; \ 271 } while (0) 272 273 READ_AR_HEADER(s, arh, sz, end); 274 275 /* 276 * Handle special archive members for the SVR4 format. 277 */ 278 if (arh.ar_name[0] == '/') { 279 if (sz == 0) 280 goto error; 281 282 e->e_flags |= LIBELF_F_AR_VARIANT_SVR4; 283 284 scanahead = 0; 285 286 /* 287 * The symbol table (file name "/ ") always comes before the 288 * string table (file name "// "). 289 */ 290 if (arh.ar_name[1] == ' ') { 291 /* "/ " => symbol table. */ 292 scanahead = 1; /* The string table to follow. */ 293 294 s += sizeof(arh); 295 e->e_u.e_ar.e_rawsymtab = s; 296 e->e_u.e_ar.e_rawsymtabsz = sz; 297 298 sz = LIBELF_ADJUST_AR_SIZE(sz); 299 s += sz; 300 301 } else if (arh.ar_name[1] == '/' && arh.ar_name[2] == ' ') { 302 /* "// " => string table for long file names. */ 303 s += sizeof(arh); 304 e->e_u.e_ar.e_rawstrtab = s; 305 e->e_u.e_ar.e_rawstrtabsz = sz; 306 307 sz = LIBELF_ADJUST_AR_SIZE(sz); 308 s += sz; 309 } 310 311 /* 312 * If the string table hasn't been seen yet, look for 313 * it in the next member. 314 */ 315 if (scanahead) { 316 READ_AR_HEADER(s, arh, sz, end); 317 318 /* "// " => string table for long file names. */ 319 if (arh.ar_name[0] == '/' && arh.ar_name[1] == '/' && 320 arh.ar_name[2] == ' ') { 321 322 s += sizeof(arh); 323 324 e->e_u.e_ar.e_rawstrtab = s; 325 e->e_u.e_ar.e_rawstrtabsz = sz; 326 327 sz = LIBELF_ADJUST_AR_SIZE(sz); 328 s += sz; 329 } 330 } 331 } else if (strncmp(arh.ar_name, LIBELF_AR_BSD_SYMTAB_NAME, 332 sizeof(LIBELF_AR_BSD_SYMTAB_NAME) - 1) == 0) { 333 /* 334 * BSD style archive symbol table. 335 */ 336 s += sizeof(arh); 337 e->e_u.e_ar.e_rawsymtab = s; 338 e->e_u.e_ar.e_rawsymtabsz = sz; 339 340 sz = LIBELF_ADJUST_AR_SIZE(sz); 341 s += sz; 342 } 343 344 /* 345 * Update the 'next' offset, so that a subsequent elf_begin() 346 * works as expected. 347 */ 348 e->e_u.e_ar.e_next = (off_t) (s - e->e_rawfile); 349 350 return (e); 351 352 error: 353 if (!reporterror) { 354 e->e_kind = ELF_K_NONE; 355 return (e); 356 } 357 358 LIBELF_SET_ERROR(ARCHIVE, 0); 359 return (NULL); 360 } 361