contrib/file/readelf.c

   1 /*
   2  * Copyright (c) Christos Zoulas 2003.
   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 immediately at the beginning of the file, without modification,
  10  *    this list of conditions, and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  18  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
  19  * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  25  * SUCH DAMAGE.
  26  */
  27 #include "file.h"
  28
  29 #ifdef BUILTIN_ELF
  30 #include <string.h>
  31 #include <ctype.h>
  32 #include <stdlib.h>
  33 #ifdef HAVE_UNISTD_H
  34 #include <unistd.h>
  35 #endif
  36
  37 #include "readelf.h"
  38
  39 #ifndef lint
  40 FILE_RCSID("@(#)$Id: readelf.c,v 1.54 2006/01/13 00:45:21 christos Exp $")
  41 #endif
  42
  43 #ifdef  ELFCORE
  44 private int dophn_core(struct magic_set *, int, int, int, off_t, int, size_t);
  45 #endif
  46 private int dophn_exec(struct magic_set *, int, int, int, off_t, int, size_t);
  47 private int doshn(struct magic_set *, int, int, int, off_t, int, size_t);
  48 private size_t donote(struct magic_set *, unsigned char *, size_t, size_t, int,
  49     int, size_t, int *);
  50
  51 #define ELF_ALIGN(a)    ((((a) + align - 1) / align) * align)
  52
  53 #define isquote(c) (strchr("'\"`", (c)) != NULL)
  54
  55 private uint16_t getu16(int, uint16_t);
  56 private uint32_t getu32(int, uint32_t);
  57 private uint64_t getu64(int, uint64_t);
  58
  59 private uint16_t
  60 getu16(int swap, uint16_t value)
  61 {
  62         union {
  63                 uint16_t ui;
  64                 char c[2];
  65         } retval, tmpval;
  66
  67         if (swap) {
  68                 tmpval.ui = value;
  69
  70                 retval.c[0] = tmpval.c[1];
  71                 retval.c[1] = tmpval.c[0];
  72
  73                 return retval.ui;
  74         } else
  75                 return value;
  76 }
  77
  78 private uint32_t
  79 getu32(int swap, uint32_t value)
  80 {
  81         union {
  82                 uint32_t ui;
  83                 char c[4];
  84         } retval, tmpval;
  85
  86         if (swap) {
  87                 tmpval.ui = value;
  88
  89                 retval.c[0] = tmpval.c[3];
  90                 retval.c[1] = tmpval.c[2];
  91                 retval.c[2] = tmpval.c[1];
  92                 retval.c[3] = tmpval.c[0];
  93
  94                 return retval.ui;
  95         } else
  96                 return value;
  97 }
  98
  99 private uint64_t
 100 getu64(int swap, uint64_t value)
 101 {
 102         union {
 103                 uint64_t ui;
 104                 char c[8];
 105         } retval, tmpval;
 106
 107         if (swap) {
 108                 tmpval.ui = value;
 109
 110                 retval.c[0] = tmpval.c[7];
 111                 retval.c[1] = tmpval.c[6];
 112                 retval.c[2] = tmpval.c[5];
 113                 retval.c[3] = tmpval.c[4];
 114                 retval.c[4] = tmpval.c[3];
 115                 retval.c[5] = tmpval.c[2];
 116                 retval.c[6] = tmpval.c[1];
 117                 retval.c[7] = tmpval.c[0];
 118
 119                 return retval.ui;
 120         } else
 121                 return value;
 122 }
 123
 124 #ifdef USE_ARRAY_FOR_64BIT_TYPES
 125 # define elf_getu64(swap, array) \
 126         ((swap ? ((uint64_t)getu32(swap, array[0])) << 32 : getu32(swap, array[0])) + \
 127          (swap ? getu32(swap, array[1]) : ((uint64_t)getu32(swap, array[1]) << 32)))
 128 #else
 129 # define elf_getu64(swap, value) getu64(swap, value)
 130 #endif
 131
 132 #define xsh_addr        (class == ELFCLASS32            \
 133                          ? (void *) &sh32               \
 134                          : (void *) &sh64)
 135 #define xsh_sizeof      (class == ELFCLASS32            \
 136                          ? sizeof sh32                  \
 137                          : sizeof sh64)
 138 #define xsh_size        (class == ELFCLASS32            \
 139                          ? getu32(swap, sh32.sh_size)   \
 140                          : getu64(swap, sh64.sh_size))
 141 #define xsh_offset      (class == ELFCLASS32            \
 142                          ? getu32(swap, sh32.sh_offset) \
 143                          : getu64(swap, sh64.sh_offset))
 144 #define xsh_type        (class == ELFCLASS32            \
 145                          ? getu32(swap, sh32.sh_type)   \
 146                          : getu32(swap, sh64.sh_type))
 147 #define xph_addr        (class == ELFCLASS32            \
 148                          ? (void *) &ph32               \
 149                          : (void *) &ph64)
 150 #define xph_sizeof      (class == ELFCLASS32            \
 151                          ? sizeof ph32                  \
 152                          : sizeof ph64)
 153 #define xph_type        (class == ELFCLASS32            \
 154                          ? getu32(swap, ph32.p_type)    \
 155                          : getu32(swap, ph64.p_type))
 156 #define xph_offset      (class == ELFCLASS32            \
 157                          ? getu32(swap, ph32.p_offset)  \
 158                          : getu64(swap, ph64.p_offset))
 159 #define xph_align       (size_t)((class == ELFCLASS32   \
 160                          ? (off_t) (ph32.p_align ?      \
 161                             getu32(swap, ph32.p_align) : 4) \
 162                          : (off_t) (ph64.p_align ?      \
 163                             getu64(swap, ph64.p_align) : 4)))
 164 #define xph_filesz      (size_t)((class == ELFCLASS32   \
 165                          ? getu32(swap, ph32.p_filesz)  \
 166                          : getu64(swap, ph64.p_filesz)))
 167 #define xnh_addr        (class == ELFCLASS32            \
 168                          ? (void *) &nh32               \
 169                          : (void *) &nh64)
 170 #define xph_memsz       (size_t)((class == ELFCLASS32   \
 171                          ? getu32(swap, ph32.p_memsz)   \
 172                          : getu64(swap, ph64.p_memsz)))
 173 #define xnh_sizeof      (class == ELFCLASS32            \
 174                          ? sizeof nh32                  \
 175                          : sizeof nh64)
 176 #define xnh_type        (class == ELFCLASS32            \
 177                          ? getu32(swap, nh32.n_type)    \
 178                          : getu32(swap, nh64.n_type))
 179 #define xnh_namesz      (class == ELFCLASS32            \
 180                          ? getu32(swap, nh32.n_namesz)  \
 181                          : getu32(swap, nh64.n_namesz))
 182 #define xnh_descsz      (class == ELFCLASS32            \
 183                          ? getu32(swap, nh32.n_descsz)  \
 184                          : getu32(swap, nh64.n_descsz))
 185 #define prpsoffsets(i)  (class == ELFCLASS32            \
 186                          ? prpsoffsets32[i]             \
 187                          : prpsoffsets64[i])
 188
 189 #ifdef ELFCORE
 190 size_t  prpsoffsets32[] = {
 191         8,              /* FreeBSD */
 192         28,             /* Linux 2.0.36 */
 193         32,             /* Linux (I forget which kernel version) */
 194         84,             /* SunOS 5.x */
 195 };
 196
 197 size_t  prpsoffsets64[] = {
 198         16,             /* FreeBSD, 64-bit */
 199         40,             /* Linux (tested on core from 2.4.x) */
 200        120,             /* SunOS 5.x, 64-bit */
 201 };
 202
 203 #define NOFFSETS32      (sizeof prpsoffsets32 / sizeof prpsoffsets32[0])
 204 #define NOFFSETS64      (sizeof prpsoffsets64 / sizeof prpsoffsets64[0])
 205
 206 #define NOFFSETS        (class == ELFCLASS32 ? NOFFSETS32 : NOFFSETS64)
 207
 208 /*
 209  * Look through the program headers of an executable image, searching
 210  * for a PT_NOTE section of type NT_PRPSINFO, with a name "CORE" or
 211  * "FreeBSD"; if one is found, try looking in various places in its
 212  * contents for a 16-character string containing only printable
 213  * characters - if found, that string should be the name of the program
 214  * that dropped core.  Note: right after that 16-character string is,
 215  * at least in SunOS 5.x (and possibly other SVR4-flavored systems) and
 216  * Linux, a longer string (80 characters, in 5.x, probably other
 217  * SVR4-flavored systems, and Linux) containing the start of the
 218  * command line for that program.
 219  *
 220  * The signal number probably appears in a section of type NT_PRSTATUS,
 221  * but that's also rather OS-dependent, in ways that are harder to
 222  * dissect with heuristics, so I'm not bothering with the signal number.
 223  * (I suppose the signal number could be of interest in situations where
 224  * you don't have the binary of the program that dropped core; if you
 225  * *do* have that binary, the debugger will probably tell you what
 226  * signal it was.)
 227  */
 228
 229 #define OS_STYLE_SVR4           0
 230 #define OS_STYLE_FREEBSD        1
 231 #define OS_STYLE_NETBSD         2
 232
 233 private const char *os_style_names[] = {
 234         "SVR4",
 235         "FreeBSD",
 236         "NetBSD",
 237 };
 238
 239 #define FLAGS_DID_CORE          1
 240
 241 private int
 242 dophn_core(struct magic_set *ms, int class, int swap, int fd, off_t off,
 243     int num, size_t size)
 244 {
 245         Elf32_Phdr ph32;
 246         Elf64_Phdr ph64;
 247         size_t offset;
 248         unsigned char nbuf[BUFSIZ];
 249         ssize_t bufsize;
 250         int flags = 0;
 251
 252         if (size != xph_sizeof) {
 253                 if (file_printf(ms, ", corrupted program header size") == -1)
 254                         return -1;
 255                 return 0;
 256         }
 257
 258         /*
 259          * Loop through all the program headers.
 260          */
 261         for ( ; num; num--) {
 262                 if (lseek(fd, off, SEEK_SET) == (off_t)-1) {
 263                         file_badseek(ms);
 264                         return -1;
 265                 }
 266                 if (read(fd, xph_addr, xph_sizeof) == -1) {
 267                         file_badread(ms);
 268                         return -1;
 269                 }
 270                 off += size;
 271                 if (xph_type != PT_NOTE)
 272                         continue;
 273
 274                 /*
 275                  * This is a PT_NOTE section; loop through all the notes
 276                  * in the section.
 277                  */
 278                 if (lseek(fd, (off_t)xph_offset, SEEK_SET) == (off_t)-1) {
 279                         file_badseek(ms);
 280                         return -1;
 281                 }
 282                 bufsize = read(fd, nbuf,
 283                     ((xph_filesz < sizeof(nbuf)) ? xph_filesz : sizeof(nbuf)));
 284                 if (bufsize == -1) {
 285                         file_badread(ms);
 286                         return -1;
 287                 }
 288                 offset = 0;
 289                 for (;;) {
 290                         if (offset >= (size_t)bufsize)
 291                                 break;
 292                         offset = donote(ms, nbuf, offset, (size_t)bufsize,
 293                             class, swap, 4, &flags);
 294                         if (offset == 0)
 295                                 break;
 296
 297                 }
 298         }
 299         return 0;
 300 }
 301 #endif
 302
 303 private size_t
 304 donote(struct magic_set *ms, unsigned char *nbuf, size_t offset, size_t size,
 305     int class, int swap, size_t align, int *flags)
 306 {
 307         Elf32_Nhdr nh32;
 308         Elf64_Nhdr nh64;
 309         size_t noff, doff;
 310 #ifdef ELFCORE
 311         int os_style = -1;
 312 #endif
 313         uint32_t namesz, descsz;
 314
 315         (void)memcpy(xnh_addr, &nbuf[offset], xnh_sizeof);
 316         offset += xnh_sizeof;
 317
 318         namesz = xnh_namesz;
 319         descsz = xnh_descsz;
 320         if ((namesz == 0) && (descsz == 0)) {
 321                 /*
 322                  * We're out of note headers.
 323                  */
 324                 return offset;
 325         }
 326
 327         if (namesz & 0x80000000) {
 328             (void)file_printf(ms, ", bad note name size 0x%lx",
 329                 (unsigned long)namesz);
 330             return offset;
 331         }
 332
 333         if (descsz & 0x80000000) {
 334             (void)file_printf(ms, ", bad note description size 0x%lx",
 335                 (unsigned long)descsz);
 336             return offset;
 337         }
 338
 339
 340         noff = offset;
 341         doff = ELF_ALIGN(offset + namesz);
 342
 343         if (offset + namesz > size) {
 344                 /*
 345                  * We're past the end of the buffer.
 346                  */
 347                 return doff;
 348         }
 349
 350         offset = ELF_ALIGN(doff + descsz);
 351         if (doff + descsz > size) {
 352                 return offset;
 353         }
 354
 355         if (namesz == 4 && strcmp((char *)&nbuf[noff], "GNU") == 0 &&
 356             xnh_type == NT_GNU_VERSION && descsz == 16) {
 357                 uint32_t desc[4];
 358                 (void)memcpy(desc, &nbuf[doff], sizeof(desc));
 359
 360                 if (file_printf(ms, ", for GNU/") == -1)
 361                         return size;
 362                 switch (getu32(swap, desc[0])) {
 363                 case GNU_OS_LINUX:
 364                         if (file_printf(ms, "Linux") == -1)
 365                                 return size;
 366                         break;
 367                 case GNU_OS_HURD:
 368                         if (file_printf(ms, "Hurd") == -1)
 369                                 return size;
 370                         break;
 371                 case GNU_OS_SOLARIS:
 372                         if (file_printf(ms, "Solaris") == -1)
 373                                 return size;
 374                         break;
 375                 default:
 376                         if (file_printf(ms, "<unknown>") == -1)
 377                                 return size;
 378                 }
 379                 if (file_printf(ms, " %d.%d.%d", getu32(swap, desc[1]),
 380                     getu32(swap, desc[2]), getu32(swap, desc[3])) == -1)
 381                         return size;
 382                 return size;
 383         }
 384
 385         if (namesz == 7 && strcmp((char *)&nbuf[noff], "NetBSD") == 0 &&
 386             xnh_type == NT_NETBSD_VERSION && descsz == 4) {
 387                 uint32_t desc;
 388                 (void)memcpy(&desc, &nbuf[doff], sizeof(desc));
 389                 desc = getu32(swap, desc);
 390
 391                 if (file_printf(ms, ", for NetBSD") == -1)
 392                         return size;
 393                 /*
 394                  * The version number used to be stuck as 199905, and was thus
 395                  * basically content-free.  Newer versions of NetBSD have fixed
 396                  * this and now use the encoding of __NetBSD_Version__:
 397                  *
 398                  *      MMmmrrpp00
 399                  *
 400                  * M = major version
 401                  * m = minor version
 402                  * r = release ["",A-Z,Z[A-Z] but numeric]
 403                  * p = patchlevel
 404                  */
 405                 if (desc > 100000000U) {
 406                         u_int ver_patch = (desc / 100) % 100;
 407                         u_int ver_rel = (desc / 10000) % 100;
 408                         u_int ver_min = (desc / 1000000) % 100;
 409                         u_int ver_maj = desc / 100000000;
 410
 411                         if (file_printf(ms, " %u.%u", ver_maj, ver_min) == -1)
 412                                 return size;
 413                         if (ver_rel == 0 && ver_patch != 0) {
 414                                 if (file_printf(ms, ".%u", ver_patch) == -1)
 415                                         return size;
 416                         } else if (ver_rel != 0) {
 417                                 while (ver_rel > 26) {
 418                                         file_printf(ms, "Z");
 419                                         ver_rel -= 26;
 420                                 }
 421                                 file_printf(ms, "%c", 'A' + ver_rel - 1);
 422                         }
 423                 }
 424                 return size;
 425         }
 426
 427         if (namesz == 8 && strcmp((char *)&nbuf[noff], "FreeBSD") == 0 &&
 428             xnh_type == NT_FREEBSD_VERSION && descsz == 4) {
 429                 uint32_t desc;
 430                 (void)memcpy(&desc, &nbuf[doff], sizeof(desc));
 431                 desc = getu32(swap, desc);
 432                 if (file_printf(ms, ", for FreeBSD") == -1)
 433                         return size;
 434
 435                 /*
 436                  * Contents is __FreeBSD_version, whose relation to OS
 437                  * versions is defined by a huge table in the Porter's
 438                  * Handbook.  This is the general scheme:
 439                  *
 440                  * Releases:
 441                  *      Mmp000 (before 4.10)
 442                  *      Mmi0p0 (before 5.0)
 443                  *      Mmm0p0
 444                  *
 445                  * Development branches:
 446                  *      Mmpxxx (before 4.6)
 447                  *      Mmp1xx (before 4.10)
 448                  *      Mmi1xx (before 5.0)
 449                  *      M000xx (pre-M.0)
 450                  *      Mmm1xx
 451                  *
 452                  * M = major version
 453                  * m = minor version
 454                  * i = minor version increment (491000 -> 4.10)
 455                  * p = patchlevel
 456                  * x = revision
 457                  *
 458                  * The first release of FreeBSD to use ELF by default
 459                  * was version 3.0.
 460                  */
 461                 if (desc == 460002) {
 462                         if (file_printf(ms, " 4.6.2") == -1)
 463                                 return size;
 464                 } else if (desc < 460100) {
 465                         if (file_printf(ms, " %d.%d", desc / 100000,
 466                             desc / 10000 % 10) == -1)
 467                                 return size;
 468                         if (desc / 1000 % 10 > 0)
 469                                 if (file_printf(ms, ".%d", desc / 1000 % 10)
 470                                     == -1)
 471                                         return size;
 472                         if ((desc % 1000 > 0) || (desc % 100000 == 0))
 473                                 if (file_printf(ms, " (%d)", desc) == -1)
 474                                         return size;
 475                 } else if (desc < 500000) {
 476                         if (file_printf(ms, " %d.%d", desc / 100000,
 477                             desc / 10000 % 10 + desc / 1000 % 10) == -1)
 478                                 return size;
 479                         if (desc / 100 % 10 > 0) {
 480                                 if (file_printf(ms, " (%d)", desc) == -1)
 481                                         return size;
 482                         } else if (desc / 10 % 10 > 0) {
 483                                 if (file_printf(ms, ".%d", desc / 10 % 10)
 484                                     == -1)
 485                                         return size;
 486                         }
 487                 } else {
 488                         if (file_printf(ms, " %d.%d", desc / 100000,
 489                             desc / 1000 % 100) == -1)
 490                                 return size;
 491                         if ((desc / 100 % 10 > 0) ||
 492                             (desc % 100000 / 100 == 0)) {
 493                                 if (file_printf(ms, " (%d)", desc) == -1)
 494                                         return size;
 495                         } else if (desc / 10 % 10 > 0) {
 496                                 if (file_printf(ms, ".%d", desc / 10 % 10)
 497                                     == -1)
 498                                         return size;
 499                         }
 500                 }
 501                 return size;
 502         }
 503
 504         if (namesz == 8 && strcmp((char *)&nbuf[noff], "OpenBSD") == 0 &&
 505             xnh_type == NT_OPENBSD_VERSION && descsz == 4) {
 506                 if (file_printf(ms, ", for OpenBSD") == -1)
 507                         return size;
 508                 /* Content of note is always 0 */
 509                 return size;
 510         }
 511
 512         if (namesz == 10 && strcmp((char *)&nbuf[noff], "DragonFly") == 0 &&
 513             xnh_type == NT_DRAGONFLY_VERSION && descsz == 4) {
 514                 uint32_t desc;
 515                 if (file_printf(ms, ", for DragonFly") == -1)
 516                         return size;
 517                 (void)memcpy(&desc, &nbuf[doff], sizeof(desc));
 518                 desc = getu32(swap, desc);
 519                 if (file_printf(ms, " %d.%d.%d", desc / 100000,
 520                     desc / 10000 % 10, desc % 10000) == -1)
 521                         return size;
 522                 return size;
 523         }
 524
 525         /*
 526          * Sigh.  The 2.0.36 kernel in Debian 2.1, at
 527          * least, doesn't correctly implement name
 528          * sections, in core dumps, as specified by
 529          * the "Program Linking" section of "UNIX(R) System
 530          * V Release 4 Programmer's Guide: ANSI C and
 531          * Programming Support Tools", because my copy
 532          * clearly says "The first 'namesz' bytes in 'name'
 533          * contain a *null-terminated* [emphasis mine]
 534          * character representation of the entry's owner
 535          * or originator", but the 2.0.36 kernel code
 536          * doesn't include the terminating null in the
 537          * name....
 538          */
 539         if ((namesz == 4 && strncmp((char *)&nbuf[noff], "CORE", 4) == 0) ||
 540             (namesz == 5 && strcmp((char *)&nbuf[noff], "CORE") == 0)) {
 541                 os_style = OS_STYLE_SVR4;
 542         }
 543
 544         if ((namesz == 8 && strcmp((char *)&nbuf[noff], "FreeBSD") == 0)) {
 545                 os_style = OS_STYLE_FREEBSD;
 546         }
 547
 548         if ((namesz >= 11 && strncmp((char *)&nbuf[noff], "NetBSD-CORE", 11)
 549             == 0)) {
 550                 os_style = OS_STYLE_NETBSD;
 551         }
 552
 553 #ifdef ELFCORE
 554         if (os_style != -1) {
 555                 if ((*flags & FLAGS_DID_CORE) == 0) {
 556                         if (file_printf(ms, ", %s-style",
 557                             os_style_names[os_style]) == -1)
 558                                 return size;
 559                         *flags |= FLAGS_DID_CORE;
 560                 }
 561         }
 562
 563         switch (os_style) {
 564         case OS_STYLE_NETBSD:
 565                 if (xnh_type == NT_NETBSD_CORE_PROCINFO) {
 566                         uint32_t signo;
 567                         /*
 568                          * Extract the program name.  It is at
 569                          * offset 0x7c, and is up to 32-bytes,
 570                          * including the terminating NUL.
 571                          */
 572                         if (file_printf(ms, ", from '%.31s'",
 573                             &nbuf[doff + 0x7c]) == -1)
 574                                 return size;
 575
 576                         /*
 577                          * Extract the signal number.  It is at
 578                          * offset 0x08.
 579                          */
 580                         (void)memcpy(&signo, &nbuf[doff + 0x08],
 581                             sizeof(signo));
 582                         if (file_printf(ms, " (signal %u)",
 583                             getu32(swap, signo)) == -1)
 584                                 return size;
 585                         return size;
 586                 }
 587                 break;
 588
 589         default:
 590                 if (xnh_type == NT_PRPSINFO) {
 591                         size_t i, j;
 592                         unsigned char c;
 593                         /*
 594                          * Extract the program name.  We assume
 595                          * it to be 16 characters (that's what it
 596                          * is in SunOS 5.x and Linux).
 597                          *
 598                          * Unfortunately, it's at a different offset
 599                          * in varous OSes, so try multiple offsets.
 600                          * If the characters aren't all printable,
 601                          * reject it.
 602                          */
 603                         for (i = 0; i < NOFFSETS; i++) {
 604                                 size_t reloffset = prpsoffsets(i);
 605                                 size_t noffset = doff + reloffset;
 606                                 for (j = 0; j < 16; j++, noffset++,
 607                                     reloffset++) {
 608                                         /*
 609                                          * Make sure we're not past
 610                                          * the end of the buffer; if
 611                                          * we are, just give up.
 612                                          */
 613                                         if (noffset >= size)
 614                                                 goto tryanother;
 615
 616                                         /*
 617                                          * Make sure we're not past
 618                                          * the end of the contents;
 619                                          * if we are, this obviously
 620                                          * isn't the right offset.
 621                                          */
 622                                         if (reloffset >= descsz)
 623                                                 goto tryanother;
 624
 625                                         c = nbuf[noffset];
 626                                         if (c == '\0') {
 627                                                 /*
 628                                                  * A '\0' at the
 629                                                  * beginning is
 630                                                  * obviously wrong.
 631                                                  * Any other '\0'
 632                                                  * means we're done.
 633                                                  */
 634                                                 if (j == 0)
 635                                                         goto tryanother;
 636                                                 else
 637                                                         break;
 638                                         } else {
 639                                                 /*
 640                                                  * A nonprintable
 641                                                  * character is also
 642                                                  * wrong.
 643                                                  */
 644                                                 if (!isprint(c) || isquote(c))
 645                                                         goto tryanother;
 646                                         }
 647                                 }
 648                                 /*
 649                                  * Well, that worked.
 650                                  */
 651                                 if (file_printf(ms, ", from '%.16s'",
 652                                     &nbuf[doff + prpsoffsets(i)]) == -1)
 653                                         return size;
 654                                 return size;
 655
 656                         tryanother:
 657                                 ;
 658                         }
 659                 }
 660                 break;
 661         }
 662 #endif
 663         return offset;
 664 }
 665
 666 private int
 667 doshn(struct magic_set *ms, int class, int swap, int fd, off_t off, int num,
 668     size_t size)
 669 {
 670         Elf32_Shdr sh32;
 671         Elf64_Shdr sh64;
 672         int stripped = 1;
 673         int flags = 0;
 674         void *nbuf;
 675         off_t noff;
 676
 677         if (size != xsh_sizeof) {
 678                 if (file_printf(ms, ", corrupted section header size") == -1)
 679                         return -1;
 680                 return 0;
 681         }
 682
 683         if (lseek(fd, off, SEEK_SET) == (off_t)-1) {
 684                 file_badseek(ms);
 685                 return -1;
 686         }
 687
 688         for ( ; num; num--) {
 689                 if (read(fd, xsh_addr, xsh_sizeof) == -1) {
 690                         file_badread(ms);
 691                         return -1;
 692                 }
 693                 switch (xsh_type) {
 694                 case SHT_SYMTAB:
 695 #if 0
 696                 case SHT_DYNSYM:
 697 #endif
 698                         stripped = 0;
 699                         break;
 700                 case SHT_NOTE:
 701                         if ((off = lseek(fd, (off_t)0, SEEK_CUR)) ==
 702                             (off_t)-1) {
 703                                 file_badread(ms);
 704                                 return -1;
 705                         }
 706                         if ((nbuf = malloc((size_t)xsh_size)) == NULL) {
 707                                 file_error(ms, errno, "Cannot allocate memory"
 708                                     " for note");
 709                                 return -1;
 710                         }
 711                         if ((noff = lseek(fd, (off_t)xsh_offset, SEEK_SET)) ==
 712                             (off_t)-1) {
 713                                 file_badread(ms);
 714                                 free(nbuf);
 715                                 return -1;
 716                         }
 717                         if (read(fd, nbuf, (size_t)xsh_size) !=
 718                             (ssize_t)xsh_size) {
 719                                 free(nbuf);
 720                                 file_badread(ms);
 721                                 return -1;
 722                         }
 723
 724                         noff = 0;
 725                         for (;;) {
 726                                 if (noff >= (size_t)xsh_size)
 727                                         break;
 728                                 noff = donote(ms, nbuf, (size_t)noff,
 729                                     (size_t)xsh_size, class, swap, 4,
 730                                     &flags);
 731                                 if (noff == 0)
 732                                         break;
 733                         }
 734                         if ((lseek(fd, off, SEEK_SET)) == (off_t)-1) {
 735                                 free(nbuf);
 736                                 file_badread(ms);
 737                                 return -1;
 738                         }
 739                         free(nbuf);
 740                         break;
 741                 }
 742         }
 743         if (file_printf(ms, ", %sstripped", stripped ? "" : "not ") == -1)
 744                 return -1;
 745         return 0;
 746 }
 747
 748 /*
 749  * Look through the program headers of an executable image, searching
 750  * for a PT_INTERP section; if one is found, it's dynamically linked,
 751  * otherwise it's statically linked.
 752  */
 753 private int
 754 dophn_exec(struct magic_set *ms, int class, int swap, int fd, off_t off,
 755     int num, size_t size)
 756 {
 757         Elf32_Phdr ph32;
 758         Elf64_Phdr ph64;
 759         const char *linking_style = "statically";
 760         const char *shared_libraries = "";
 761         unsigned char nbuf[BUFSIZ];
 762         int bufsize;
 763         size_t offset, align;
 764         off_t savedoffset;
 765         int flags = 0;
 766
 767         if (size != xph_sizeof) {
 768                 if (file_printf(ms, ", corrupted program header size") == -1)
 769                     return -1;
 770                 return 0;
 771         }
 772         if (lseek(fd, off, SEEK_SET) == (off_t)-1) {
 773                 file_badseek(ms);
 774                 return -1;
 775         }
 776
 777         for ( ; num; num--) {
 778                 if (read(fd, xph_addr, xph_sizeof) == -1) {
 779                         file_badread(ms);
 780                         return -1;
 781                 }
 782                 if ((savedoffset = lseek(fd, (off_t)0, SEEK_CUR)) == (off_t)-1) {
 783                         file_badseek(ms);
 784                         return -1;
 785                 }
 786
 787                 switch (xph_type) {
 788                 case PT_DYNAMIC:
 789                         linking_style = "dynamically";
 790                         break;
 791                 case PT_INTERP:
 792                         shared_libraries = " (uses shared libs)";
 793                         break;
 794                 case PT_NOTE:
 795                         if ((align = xph_align) & 0x80000000) {
 796                                 if (file_printf(ms,
 797                                     ", invalid note alignment 0x%lx",
 798                                     (unsigned long)align) == -1)
 799                                         return -1;
 800                                 align = 4;
 801                         }
 802                         /*
 803                          * This is a PT_NOTE section; loop through all the notes
 804                          * in the section.
 805                          */
 806                         if (lseek(fd, (off_t)xph_offset, SEEK_SET)
 807                             == (off_t)-1) {
 808                                 file_badseek(ms);
 809                                 return -1;
 810                         }
 811                         bufsize = read(fd, nbuf, ((xph_filesz < sizeof(nbuf)) ?
 812                             xph_filesz : sizeof(nbuf)));
 813                         if (bufsize == -1) {
 814                                 file_badread(ms);
 815                                 return -1;
 816                         }
 817                         offset = 0;
 818                         for (;;) {
 819                                 if (offset >= (size_t)bufsize)
 820                                         break;
 821                                 offset = donote(ms, nbuf, offset,
 822                                     (size_t)bufsize, class, swap, align,
 823                                     &flags);
 824                                 if (offset == 0)
 825                                         break;
 826                         }
 827                         if (lseek(fd, savedoffset, SEEK_SET) == (off_t)-1) {
 828                                 file_badseek(ms);
 829                                 return -1;
 830                         }
 831                         break;
 832                 }
 833         }
 834         if (file_printf(ms, ", %s linked%s", linking_style, shared_libraries)
 835             == -1)
 836             return -1;
 837         return 0;
 838 }
 839
 840
 841 protected int
 842 file_tryelf(struct magic_set *ms, int fd, const unsigned char *buf,
 843     size_t nbytes)
 844 {
 845         union {
 846                 int32_t l;
 847                 char c[sizeof (int32_t)];
 848         } u;
 849         int class;
 850         int swap;
 851
 852         /*
 853          * If we cannot seek, it must be a pipe, socket or fifo.
 854          */
 855         if((lseek(fd, (off_t)0, SEEK_SET) == (off_t)-1) && (errno == ESPIPE))
 856                 fd = file_pipe2file(ms, fd, buf, nbytes);
 857
 858         /*
 859          * ELF executables have multiple section headers in arbitrary
 860          * file locations and thus file(1) cannot determine it from easily.
 861          * Instead we traverse thru all section headers until a symbol table
 862          * one is found or else the binary is stripped.
 863          */
 864         if (buf[EI_MAG0] != ELFMAG0
 865             || (buf[EI_MAG1] != ELFMAG1 && buf[EI_MAG1] != OLFMAG1)
 866             || buf[EI_MAG2] != ELFMAG2 || buf[EI_MAG3] != ELFMAG3)
 867             return 0;
 868
 869
 870         class = buf[4];
 871
 872         if (class == ELFCLASS32) {
 873                 Elf32_Ehdr elfhdr;
 874                 if (nbytes <= sizeof (Elf32_Ehdr))
 875                         return 0;
 876
 877
 878                 u.l = 1;
 879                 (void) memcpy(&elfhdr, buf, sizeof elfhdr);
 880                 swap = (u.c[sizeof(int32_t) - 1] + 1) != elfhdr.e_ident[5];
 881
 882                 if (getu16(swap, elfhdr.e_type) == ET_CORE) {
 883 #ifdef ELFCORE
 884                         if (dophn_core(ms, class, swap, fd,
 885                             (off_t)getu32(swap, elfhdr.e_phoff),
 886                             getu16(swap, elfhdr.e_phnum),
 887                             (size_t)getu16(swap, elfhdr.e_phentsize)) == -1)
 888                                 return -1;
 889 #else
 890                         ;
 891 #endif
 892                 } else {
 893                         if (getu16(swap, elfhdr.e_type) == ET_EXEC) {
 894                                 if (dophn_exec(ms, class, swap,
 895                                     fd, (off_t)getu32(swap, elfhdr.e_phoff),
 896                                     getu16(swap, elfhdr.e_phnum),
 897                                     (size_t)getu16(swap, elfhdr.e_phentsize))
 898                                     == -1)
 899                                         return -1;
 900                         }
 901                         if (doshn(ms, class, swap, fd,
 902                             (off_t)getu32(swap, elfhdr.e_shoff),
 903                             getu16(swap, elfhdr.e_shnum),
 904                             (size_t)getu16(swap, elfhdr.e_shentsize)) == -1)
 905                                 return -1;
 906                 }
 907                 return 1;
 908         }
 909
 910         if (class == ELFCLASS64) {
 911                 Elf64_Ehdr elfhdr;
 912                 if (nbytes <= sizeof (Elf64_Ehdr))
 913                         return 0;
 914
 915
 916                 u.l = 1;
 917                 (void) memcpy(&elfhdr, buf, sizeof elfhdr);
 918                 swap = (u.c[sizeof(int32_t) - 1] + 1) != elfhdr.e_ident[5];
 919
 920                 if (getu16(swap, elfhdr.e_type) == ET_CORE) {
 921 #ifdef ELFCORE
 922                         if (dophn_core(ms, class, swap, fd,
 923                             (off_t)elf_getu64(swap, elfhdr.e_phoff),
 924                             getu16(swap, elfhdr.e_phnum),
 925                             (size_t)getu16(swap, elfhdr.e_phentsize)) == -1)
 926                                 return -1;
 927 #else
 928                         ;
 929 #endif
 930                 } else {
 931                         if (getu16(swap, elfhdr.e_type) == ET_EXEC) {
 932                                 if (dophn_exec(ms, class, swap, fd,
 933                                     (off_t)elf_getu64(swap, elfhdr.e_phoff),
 934                                     getu16(swap, elfhdr.e_phnum),
 935                                     (size_t)getu16(swap, elfhdr.e_phentsize))
 936                                     == -1)
 937                                         return -1;
 938                         }
 939                         if (doshn(ms, class, swap, fd,
 940                             (off_t)elf_getu64(swap, elfhdr.e_shoff),
 941                             getu16(swap, elfhdr.e_shnum),
 942                             (size_t)getu16(swap, elfhdr.e_shentsize)) == -1)
 943                                 return -1;
 944                 }
 945                 return 1;
 946         }
 947         return 0;
 948 }
 949 #endif