lib/libelf/libelf_ar_util.c

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