utils/ldd.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * A small little ldd implementation for uClibc
   4  *
   5  * Copyright (C) 2000-2006 Erik Andersen <andersen@uclibc.org>
   6  *
   7  * Several functions in this file (specifically, elf_find_section_type(),
   8  * elf_find_phdr_type(), and elf_find_dynamic(), were stolen from elflib.c from
   9  * elfvector (http://www.BitWagon.com/elfvector.html) by John F. Reiser
  10  * <jreiser@BitWagon.com>, which is copyright 2000 BitWagon Software LLC
  11  * (GPL2).
  12  *
  13  * Licensed under GPLv2 or later
  14  */
  15
  16 #include "porting.h"
  17
  18 #if defined(__alpha__)
  19 #define MATCH_MACHINE(x) (x == EM_ALPHA)
  20 #define ELFCLASSM       ELFCLASS64
  21 #endif
  22
  23 #if defined(__arm__) || defined(__thumb__)
  24 #define MATCH_MACHINE(x) (x == EM_ARM)
  25 #define ELFCLASSM       ELFCLASS32
  26 #endif
  27
  28 #if defined(__avr32__)
  29 #define MATCH_MACHINE(x) (x == EM_AVR32)
  30 #define ELFCLASSM      ELFCLASS32
  31 #endif
  32
  33 #if defined(__s390__)
  34 #define MATCH_MACHINE(x) (x == EM_S390)
  35 #define ELFCLASSM       ELFCLASS32
  36 #endif
  37
  38 #if defined(__hppa__)
  39 #define MATCH_MACHINE(x) (x == EM_PARISC)
  40 #if defined(__LP64__)
  41 #define ELFCLASSM               ELFCLASS64
  42 #else
  43 #define ELFCLASSM               ELFCLASS32
  44 #endif
  45 #endif
  46
  47 #if defined(__i386__)
  48 #ifndef EM_486
  49 #define MATCH_MACHINE(x) (x == EM_386)
  50 #else
  51 #define MATCH_MACHINE(x) (x == EM_386 || x == EM_486)
  52 #endif
  53 #define ELFCLASSM       ELFCLASS32
  54 #endif
  55
  56 #if defined(__ia64__)
  57 #define MATCH_MACHINE(x) (x == EM_IA_64)
  58 #define ELFCLASSM       ELFCLASS64
  59 #endif
  60
  61 #if defined(__mc68000__)
  62 #define MATCH_MACHINE(x) (x == EM_68K)
  63 #define ELFCLASSM       ELFCLASS32
  64 #endif
  65
  66 #if defined(__mips__)
  67 #define MATCH_MACHINE(x) (x == EM_MIPS || x == EM_MIPS_RS3_LE)
  68 #define ELFCLASSM       ELFCLASS32
  69 #endif
  70
  71 #if defined(__powerpc64__)
  72 #define MATCH_MACHINE(x) (x == EM_PPC64)
  73 #define ELFCLASSM       ELFCLASS64
  74 #elif defined(__powerpc__)
  75 #define MATCH_MACHINE(x) (x == EM_PPC)
  76 #define ELFCLASSM       ELFCLASS32
  77 #endif
  78
  79 #if defined(__sh__)
  80 #define MATCH_MACHINE(x) (x == EM_SH)
  81 #define ELFCLASSM       ELFCLASS32
  82 #endif
  83
  84 #if defined(__v850e__)
  85 #define MATCH_MACHINE(x) ((x) == EM_V850 || (x) == EM_CYGNUS_V850)
  86 #define ELFCLASSM       ELFCLASS32
  87 #endif
  88
  89 #if defined(__sparc__)
  90 #define MATCH_MACHINE(x) ((x) == EM_SPARC || (x) == EM_SPARC32PLUS)
  91 #define ELFCLASSM    ELFCLASS32
  92 #endif
  93
  94 #if defined(__cris__)
  95 #define MATCH_MACHINE(x) (x == EM_CRIS)
  96 #define ELFCLASSM       ELFCLASS32
  97 #endif
  98
  99 #if defined(__x86_64__)
 100 #define MATCH_MACHINE(x) (x == EM_X86_64)
 101 #define ELFCLASSM       ELFCLASS64
 102 #endif
 103
 104 #if defined(__microblaze__)
 105 #define MATCH_MACHINE(x) (x == EM_MICROBLAZE_OLD)
 106 #define ELFCLASSM       ELFCLASS32
 107 #endif
 108
 109 #ifndef MATCH_MACHINE
 110 # ifdef __linux__
 111 #  include <asm/elf.h>
 112 # endif
 113 # ifdef ELF_ARCH
 114 #  define MATCH_MACHINE(x) (x == ELF_ARCH)
 115 # endif
 116 # ifdef ELF_CLASS
 117 #  define ELFCLASSM ELF_CLASS
 118 # endif
 119 #endif
 120 #ifndef MATCH_MACHINE
 121 # warning "You really should add a MATCH_MACHINE() macro for your architecture"
 122 #endif
 123
 124 #if UCLIBC_ENDIAN_HOST == UCLIBC_ENDIAN_LITTLE
 125 #define ELFDATAM        ELFDATA2LSB
 126 #elif UCLIBC_ENDIAN_HOST == UCLIBC_ENDIAN_BIG
 127 #define ELFDATAM        ELFDATA2MSB
 128 #endif
 129
 130 #define ARRAY_SIZE(v)   (sizeof(v) / sizeof(*v))
 131 #define TRUSTED_LDSO    UCLIBC_RUNTIME_PREFIX "lib/" UCLIBC_LDSO
 132
 133 struct library {
 134         char *name;
 135         int resolved;
 136         char *path;
 137         struct library *next;
 138 };
 139 static struct library *lib_list = NULL;
 140 static char not_found[] = "not found";
 141 static char *interp_name = NULL;
 142 static char *interp_dir = NULL;
 143 static int byteswap;
 144 static int interpreter_already_found = 0;
 145
 146 static __inline__ uint32_t byteswap32_to_host(uint32_t value)
 147 {
 148         if (byteswap == 1) {
 149                 return (bswap_32(value));
 150         } else {
 151                 return (value);
 152         }
 153 }
 154 static __inline__ uint64_t byteswap64_to_host(uint64_t value)
 155 {
 156         if (byteswap == 1) {
 157                 return (bswap_64(value));
 158         } else {
 159                 return (value);
 160         }
 161 }
 162
 163 #if ELFCLASSM == ELFCLASS32
 164 # define byteswap_to_host(x) byteswap32_to_host(x)
 165 #else
 166 # define byteswap_to_host(x) byteswap64_to_host(x)
 167 #endif
 168
 169 static ElfW(Shdr) *elf_find_section_type(uint32_t key, ElfW(Ehdr) *ehdr)
 170 {
 171         int j;
 172         ElfW(Shdr) *shdr;
 173         shdr = (ElfW(Shdr) *) (ehdr->e_shoff + (char *)ehdr);
 174         for (j = ehdr->e_shnum; --j >= 0; ++shdr) {
 175                 if (key == byteswap32_to_host(shdr->sh_type)) {
 176                         return shdr;
 177                 }
 178         }
 179         return NULL;
 180 }
 181
 182 static ElfW(Phdr) *elf_find_phdr_type(uint32_t type, ElfW(Ehdr) *ehdr)
 183 {
 184         int j;
 185         ElfW(Phdr) *phdr = (ElfW(Phdr) *) (ehdr->e_phoff + (char *)ehdr);
 186         for (j = ehdr->e_phnum; --j >= 0; ++phdr) {
 187                 if (type == byteswap32_to_host(phdr->p_type)) {
 188                         return phdr;
 189                 }
 190         }
 191         return NULL;
 192 }
 193
 194 /* Returns value if return_val==1, ptr otherwise */
 195 static void *elf_find_dynamic(int64_t const key, ElfW(Dyn) *dynp,
 196                        ElfW(Ehdr) *ehdr, int return_val)
 197 {
 198         ElfW(Phdr) *pt_text = elf_find_phdr_type(PT_LOAD, ehdr);
 199         unsigned tx_reloc = byteswap_to_host(pt_text->p_vaddr) - byteswap_to_host(pt_text->p_offset);
 200         for (; DT_NULL != byteswap_to_host(dynp->d_tag); ++dynp) {
 201                 if (key == byteswap_to_host(dynp->d_tag)) {
 202                         if (return_val == 1)
 203                                 return (void *)byteswap_to_host(dynp->d_un.d_val);
 204                         else
 205                                 return (void *)(byteswap_to_host(dynp->d_un.d_val) - tx_reloc + (char *)ehdr);
 206                 }
 207         }
 208         return NULL;
 209 }
 210
 211 static char *elf_find_rpath(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic)
 212 {
 213         ElfW(Dyn) *dyns;
 214
 215         for (dyns = dynamic; byteswap_to_host(dyns->d_tag) != DT_NULL; ++dyns) {
 216                 if (DT_RPATH == byteswap_to_host(dyns->d_tag)) {
 217                         char *strtab;
 218                         strtab = (char *)elf_find_dynamic(DT_STRTAB, dynamic, ehdr, 0);
 219                         return ((char *)strtab + byteswap_to_host(dyns->d_un.d_val));
 220                 }
 221         }
 222         return NULL;
 223 }
 224
 225 static int check_elf_header(ElfW(Ehdr) *const ehdr)
 226 {
 227         if (!ehdr || *(uint32_t*)ehdr != ELFMAG_U32
 228          || ehdr->e_ident[EI_CLASS] != ELFCLASSM
 229          || ehdr->e_ident[EI_VERSION] != EV_CURRENT
 230         ) {
 231                 return 1;
 232         }
 233
 234         /* Check if the target endianness matches the host's endianness */
 235         byteswap = 0;
 236         if (UCLIBC_ENDIAN_HOST == UCLIBC_ENDIAN_LITTLE) {
 237                 if (ehdr->e_ident[5] == ELFDATA2MSB)
 238                         byteswap = 1;
 239         } else if (UCLIBC_ENDIAN_HOST == UCLIBC_ENDIAN_BIG) {
 240                 if (ehdr->e_ident[5] == ELFDATA2LSB)
 241                         byteswap = 1;
 242         }
 243
 244         /* Be very lazy, and only byteswap the stuff we use */
 245         if (byteswap) {
 246                 ehdr->e_type = bswap_16(ehdr->e_type);
 247                 ehdr->e_phoff = byteswap_to_host(ehdr->e_phoff);
 248                 ehdr->e_shoff = byteswap_to_host(ehdr->e_shoff);
 249                 ehdr->e_phnum = bswap_16(ehdr->e_phnum);
 250                 ehdr->e_shnum = bswap_16(ehdr->e_shnum);
 251         }
 252
 253         return 0;
 254 }
 255
 256 #ifdef __LDSO_CACHE_SUPPORT__
 257 static caddr_t cache_addr = NULL;
 258 static size_t cache_size = 0;
 259
 260 static int map_cache(void)
 261 {
 262         int fd;
 263         struct stat st;
 264         header_t *header;
 265         libentry_t *libent;
 266         int i, strtabsize;
 267
 268         if (cache_addr == (caddr_t) - 1)
 269                 return -1;
 270         else if (cache_addr != NULL)
 271                 return 0;
 272
 273         if (stat(LDSO_CACHE, &st) || (fd = open(LDSO_CACHE, O_RDONLY)) < 0) {
 274                 fprintf(stderr, "ldd: can't open cache '%s'\n", LDSO_CACHE);
 275                 cache_addr = (caddr_t) - 1;     /* so we won't try again */
 276                 return -1;
 277         }
 278
 279         cache_size = st.st_size;
 280         cache_addr = mmap(0, cache_size, PROT_READ, MAP_SHARED, fd, 0);
 281         close(fd);
 282         if (cache_addr == MAP_FAILED) {
 283                 fprintf(stderr, "ldd: can't map cache '%s'\n", LDSO_CACHE);
 284                 return -1;
 285         }
 286
 287         header = (header_t *) cache_addr;
 288
 289         if (cache_size < sizeof(header_t)
 290             || memcmp(header->magic, LDSO_CACHE_MAGIC, LDSO_CACHE_MAGIC_LEN)
 291             || memcmp(header->version, LDSO_CACHE_VER, LDSO_CACHE_VER_LEN)
 292             || cache_size < (sizeof(header_t) + header->nlibs * sizeof(libentry_t))
 293             || cache_addr[cache_size - 1] != '\0')
 294         {
 295                 fprintf(stderr, "ldd: cache '%s' is corrupt\n", LDSO_CACHE);
 296                 goto fail;
 297         }
 298
 299         strtabsize = cache_size - sizeof(header_t) - header->nlibs * sizeof(libentry_t);
 300         libent = (libentry_t *) & header[1];
 301
 302         for (i = 0; i < header->nlibs; i++) {
 303                 if (libent[i].sooffset >= strtabsize || libent[i].liboffset >= strtabsize) {
 304                         fprintf(stderr, "ldd: cache '%s' is corrupt\n", LDSO_CACHE);
 305                         goto fail;
 306                 }
 307         }
 308
 309         return 0;
 310
 311 fail:
 312         munmap(cache_addr, cache_size);
 313         cache_addr = (caddr_t) - 1;
 314         return -1;
 315 }
 316
 317 static int unmap_cache(void)
 318 {
 319         if (cache_addr == NULL || cache_addr == (caddr_t) - 1)
 320                 return -1;
 321
 322 #if 1
 323         munmap(cache_addr, cache_size);
 324         cache_addr = NULL;
 325 #endif
 326
 327         return 0;
 328 }
 329 #else
 330 static __inline__ void map_cache(void)
 331 {
 332 }
 333 static __inline__ void unmap_cache(void)
 334 {
 335 }
 336 #endif
 337
 338 /* This function's behavior must exactly match that
 339  * in uClibc/ldso/ldso/dl-elf.c */
 340 static void search_for_named_library(char *name, char *result,
 341                                      const char *path_list)
 342 {
 343         int i, count = 1;
 344         char *path, *path_n;
 345         struct stat filestat;
 346
 347         /* We need a writable copy of this string */
 348         path = strdup(path_list);
 349         if (!path) {
 350                 fprintf(stderr, "%s: Out of memory!\n", __func__);
 351                 exit(EXIT_FAILURE);
 352         }
 353         /* Eliminate all double //s */
 354         path_n = path;
 355         while ((path_n = strstr(path_n, "//"))) {
 356                 i = strlen(path_n);
 357                 memmove(path_n, path_n + 1, i - 1);
 358                 *(path_n + i - 1) = '\0';
 359         }
 360
 361         /* Replace colons with zeros in path_list and count them */
 362         for (i = strlen(path); i > 0; i--) {
 363                 if (path[i] == ':') {
 364                         path[i] = 0;
 365                         count++;
 366                 }
 367         }
 368         path_n = path;
 369         for (i = 0; i < count; i++) {
 370                 strcpy(result, path_n);
 371                 strcat(result, "/");
 372                 strcat(result, name);
 373                 if (stat(result, &filestat) == 0 && filestat.st_mode & S_IRUSR) {
 374                         free(path);
 375                         return;
 376                 }
 377                 path_n += (strlen(path_n) + 1);
 378         }
 379         free(path);
 380         *result = '\0';
 381 }
 382
 383 static void locate_library_file(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic,
 384                                 int is_suid, struct library *lib)
 385 {
 386         char *buf;
 387         char *path;
 388         struct stat filestat;
 389
 390         /* If this is a fully resolved name, our job is easy */
 391         if (stat(lib->name, &filestat) == 0) {
 392                 lib->path = strdup(lib->name);
 393                 return;
 394         }
 395
 396         /* We need some elbow room here.  Make some room... */
 397         buf = malloc(1024);
 398         if (!buf) {
 399                 fprintf(stderr, "%s: Out of memory!\n", __func__);
 400                 exit(EXIT_FAILURE);
 401         }
 402
 403         /* This function must match the behavior of _dl_load_shared_library
 404          * in readelflib1.c or things won't work out as expected... */
 405
 406         /* The ABI specifies that RPATH is searched first, so do that now.  */
 407         path = elf_find_rpath(ehdr, dynamic);
 408         if (path) {
 409                 search_for_named_library(lib->name, buf, path);
 410                 if (*buf != '\0') {
 411                         lib->path = buf;
 412                         return;
 413                 }
 414         }
 415
 416         /* Next check LD_{ELF_}LIBRARY_PATH if specified and allowed.
 417          * Since this app doesn't actually run an executable I will skip
 418          * the suid check, and just use LD_{ELF_}LIBRARY_PATH if set */
 419         if (is_suid == 1)
 420                 path = NULL;
 421         else
 422                 path = getenv("LD_LIBRARY_PATH");
 423         if (path) {
 424                 search_for_named_library(lib->name, buf, path);
 425                 if (*buf != '\0') {
 426                         lib->path = buf;
 427                         return;
 428                 }
 429         }
 430 #ifdef __LDSO_CACHE_SUPPORT__
 431         if (cache_addr != NULL && cache_addr != (caddr_t) - 1) {
 432                 int i;
 433                 header_t *header = (header_t *) cache_addr;
 434                 libentry_t *libent = (libentry_t *) & header[1];
 435                 char *strs = (char *)&libent[header->nlibs];
 436
 437                 for (i = 0; i < header->nlibs; i++) {
 438                         if ((libent[i].flags == LIB_ELF ||
 439                              libent[i].flags == LIB_ELF_LIBC0 ||
 440                              libent[i].flags == LIB_ELF_LIBC5) &&
 441                             strcmp(lib->name, strs + libent[i].sooffset) == 0)
 442                         {
 443                                 lib->path = strdup(strs + libent[i].liboffset);
 444                                 return;
 445                         }
 446                 }
 447         }
 448 #endif
 449
 450         /* Next look for libraries wherever the shared library
 451          * loader was installed -- this is usually where we
 452          * should find things... */
 453         if (interp_dir) {
 454                 search_for_named_library(lib->name, buf, interp_dir);
 455                 if (*buf != '\0') {
 456                         lib->path = buf;
 457                         return;
 458                 }
 459         }
 460
 461         /* Lastly, search the standard list of paths for the library.
 462            This list must exactly match the list in uClibc/ldso/ldso/dl-elf.c */
 463         path = UCLIBC_RUNTIME_PREFIX "lib:" UCLIBC_RUNTIME_PREFIX "usr/lib"
 464 #ifndef __LDSO_CACHE_SUPPORT__
 465             ":" UCLIBC_RUNTIME_PREFIX "usr/X11R6/lib"
 466 #endif
 467             ;
 468         search_for_named_library(lib->name, buf, path);
 469         if (*buf != '\0') {
 470                 lib->path = buf;
 471         } else {
 472                 free(buf);
 473                 lib->path = not_found;
 474         }
 475 }
 476
 477 static int add_library(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic, int is_setuid, char *s)
 478 {
 479         char *tmp, *tmp1, *tmp2;
 480         struct library *cur, *newlib = lib_list;
 481
 482         if (!s || !strlen(s))
 483                 return 1;
 484
 485         tmp = s;
 486         while (*tmp) {
 487                 if (*tmp == '/')
 488                         s = tmp + 1;
 489                 tmp++;
 490         }
 491
 492         /* We add ldso elsewhere */
 493         if (interpreter_already_found && (tmp = strrchr(interp_name, '/')) != NULL) {
 494                 int len = strlen(interp_dir);
 495                 if (strcmp(s, interp_name + 1 + len) == 0)
 496                         return 1;
 497         }
 498
 499         for (cur = lib_list; cur; cur = cur->next) {
 500                 /* Check if this library is already in the list */
 501                 tmp1 = tmp2 = cur->name;
 502                 while (*tmp1) {
 503                         if (*tmp1 == '/')
 504                                 tmp2 = tmp1 + 1;
 505                         tmp1++;
 506                 }
 507                 if (strcmp(tmp2, s) == 0) {
 508                         /*printf("find_elf_interpreter is skipping '%s' (already in list)\n", cur->name); */
 509                         return 0;
 510                 }
 511         }
 512
 513         /* Ok, this lib needs to be added to the list */
 514         newlib = malloc(sizeof(struct library));
 515         if (!newlib)
 516                 return 1;
 517         newlib->name = malloc(strlen(s) + 1);
 518         strcpy(newlib->name, s);
 519         newlib->resolved = 0;
 520         newlib->path = NULL;
 521         newlib->next = NULL;
 522
 523         /* Now try and locate where this library might be living... */
 524         locate_library_file(ehdr, dynamic, is_setuid, newlib);
 525
 526         /*printf("add_library is adding '%s' to '%s'\n", newlib->name, newlib->path); */
 527         if (!lib_list) {
 528                 lib_list = newlib;
 529         } else {
 530                 for (cur = lib_list; cur->next; cur = cur->next) ;      /* nothing */
 531                 cur->next = newlib;
 532         }
 533         return 0;
 534 }
 535
 536 static void find_needed_libraries(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic, int is_setuid)
 537 {
 538         ElfW(Dyn) *dyns;
 539
 540         for (dyns = dynamic; byteswap_to_host(dyns->d_tag) != DT_NULL; ++dyns) {
 541                 if (DT_NEEDED == byteswap_to_host(dyns->d_tag)) {
 542                         char *strtab;
 543                         strtab = (char *)elf_find_dynamic(DT_STRTAB, dynamic, ehdr, 0);
 544                         add_library(ehdr, dynamic, is_setuid, (char *)strtab + byteswap_to_host(dyns->d_un.d_val));
 545                 }
 546         }
 547 }
 548
 549 static struct library *find_elf_interpreter(ElfW(Ehdr) *ehdr)
 550 {
 551         ElfW(Phdr) *phdr;
 552
 553         if (interpreter_already_found == 1)
 554                 return NULL;
 555         phdr = elf_find_phdr_type(PT_INTERP, ehdr);
 556         if (phdr) {
 557                 struct library *cur, *newlib = NULL;
 558                 char *s = (char *)ehdr + byteswap_to_host(phdr->p_offset);
 559
 560                 char *tmp, *tmp1;
 561                 interp_name = strdup(s);
 562                 interp_dir = strdup(s);
 563                 tmp = strrchr(interp_dir, '/');
 564                 if (tmp)
 565                         *tmp = '\0';
 566                 else {
 567                         free(interp_dir);
 568                         interp_dir = interp_name;
 569                 }
 570                 tmp1 = tmp = s;
 571                 while (*tmp) {
 572                         if (*tmp == '/')
 573                                 tmp1 = tmp + 1;
 574                         tmp++;
 575                 }
 576                 for (cur = lib_list; cur; cur = cur->next) {
 577                         /* Check if this library is already in the list */
 578                         if (strcmp(cur->name, tmp1) == 0) {
 579                                 /*printf("find_elf_interpreter is replacing '%s' (already in list)\n", cur->name); */
 580                                 newlib = cur;
 581                                 free(newlib->name);
 582                                 if (newlib->path != not_found) {
 583                                         free(newlib->path);
 584                                 }
 585                                 newlib->name = NULL;
 586                                 newlib->path = NULL;
 587                                 break;
 588                         }
 589                 }
 590                 if (newlib == NULL)
 591                         newlib = malloc(sizeof(struct library));
 592                 if (!newlib)
 593                         return NULL;
 594                 newlib->name = malloc(strlen(s) + 1);
 595                 strcpy(newlib->name, s);
 596                 newlib->path = strdup(newlib->name);
 597                 newlib->resolved = 1;
 598                 newlib->next = NULL;
 599
 600 #if 0
 601                 /*printf("find_elf_interpreter is adding '%s' to '%s'\n", newlib->name, newlib->path); */
 602                 if (!lib_list) {
 603                         lib_list = newlib;
 604                 } else {
 605                         for (cur = lib_list; cur->next; cur = cur->next) ;      /* nothing */
 606                         cur->next = newlib;
 607                 }
 608 #endif
 609                 interpreter_already_found = 1;
 610                 return newlib;
 611         }
 612         return NULL;
 613 }
 614
 615 /* map the .so, and locate interesting pieces */
 616 /*
 617 #warning "There may be two warnings here about vfork() clobbering, ignore them"
 618 */
 619 static int find_dependencies(char *filename)
 620 {
 621         int is_suid = 0;
 622         FILE *thefile;
 623         struct library *interp;
 624         struct stat statbuf;
 625         ElfW(Ehdr) *ehdr = NULL;
 626         ElfW(Shdr) *dynsec = NULL;
 627         ElfW(Dyn) *dynamic = NULL;
 628
 629         if (filename == not_found)
 630                 return 0;
 631
 632         if (!filename) {
 633                 fprintf(stderr, "No filename specified.\n");
 634                 return -1;
 635         }
 636         if (!(thefile = fopen(filename, "r"))) {
 637                 perror(filename);
 638                 return -1;
 639         }
 640         if (fstat(fileno(thefile), &statbuf) < 0) {
 641                 perror(filename);
 642                 fclose(thefile);
 643                 return -1;
 644         }
 645
 646         if ((size_t) statbuf.st_size < sizeof(ElfW(Ehdr)))
 647                 goto foo;
 648
 649         if (!S_ISREG(statbuf.st_mode))
 650                 goto foo;
 651
 652         /* mmap the file to make reading stuff from it effortless */
 653         ehdr = mmap(0, statbuf.st_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fileno(thefile), 0);
 654         if (ehdr == MAP_FAILED) {
 655                 fclose(thefile);
 656                 fprintf(stderr, "mmap(%s) failed: %s\n", filename, strerror(errno));
 657                 return -1;
 658         }
 659
 660 foo:
 661         fclose(thefile);
 662
 663         /* Check if this looks like a legit ELF file */
 664         if (check_elf_header(ehdr)) {
 665                 fprintf(stderr, "%s: not an ELF file.\n", filename);
 666                 return -1;
 667         }
 668         /* Check if this is the right kind of ELF file */
 669         if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) {
 670                 fprintf(stderr, "%s: not a dynamic executable\n", filename);
 671                 return -1;
 672         }
 673         if (ehdr->e_type == ET_EXEC || ehdr->e_type == ET_DYN) {
 674                 if (statbuf.st_mode & S_ISUID)
 675                         is_suid = 1;
 676                 if ((statbuf.st_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP))
 677                         is_suid = 1;
 678                 /* FIXME */
 679                 if (is_suid)
 680                         fprintf(stderr, "%s: is setuid\n", filename);
 681         }
 682
 683         interpreter_already_found = 0;
 684         interp = find_elf_interpreter(ehdr);
 685
 686 #ifdef __LDSO_LDD_SUPPORT__
 687         if (interp
 688             && (ehdr->e_type == ET_EXEC || ehdr->e_type == ET_DYN)
 689             && ehdr->e_ident[EI_CLASS] == ELFCLASSM
 690             && ehdr->e_ident[EI_DATA] == ELFDATAM
 691             && ehdr->e_ident[EI_VERSION] == EV_CURRENT
 692             && MATCH_MACHINE(ehdr->e_machine))
 693         {
 694                 struct stat st;
 695                 if (stat(interp->path, &st) == 0 && S_ISREG(st.st_mode)) {
 696                         pid_t pid;
 697                         int status;
 698                         static const char *const environment[] = {
 699                                 "PATH=/usr/bin:/bin:/usr/sbin:/sbin",
 700                                 "SHELL=/bin/sh",
 701                                 "LD_TRACE_LOADED_OBJECTS=1",
 702                                 NULL
 703                         };
 704                         char * lib_path = getenv("LD_LIBRARY_PATH");
 705
 706 #ifdef __LDSO_STANDALONE_SUPPORT__
 707                         /* The 'extended' environment inclusing the LD_LIBRARY_PATH */
 708                         static char *ext_environment[ARRAY_SIZE(environment) + 1];
 709                         char **envp = (char **) environment;
 710
 711                         if (lib_path) {
 712                                 /*
 713                                  * If the LD_LIBRARY_PATH is set, it needs to include it
 714                                  * into the environment for the new process to be spawned
 715                                  */
 716                                 char ** eenvp = (char **) ext_environment;
 717
 718                                 /* Copy the N-1 environment's entries */
 719                                 while (*envp)
 720                                         *eenvp++=*envp++;
 721
 722                                 /* Make room for LD_LIBRARY_PATH */
 723                                 *eenvp = (char *) malloc(sizeof("LD_LIBRARY_PATH=")
 724                                                                           + strlen(lib_path));
 725                                 strcpy(*eenvp, "LD_LIBRARY_PATH=");
 726                                 strcat(*eenvp, lib_path);
 727                                 lib_path = *eenvp;
 728                                 /* ext_environment[size] is already NULL */
 729
 730                                 /* Use the extended environment */
 731                                 envp = ext_environment;
 732                         }
 733                         if ((pid = vfork()) == 0) {
 734                                 /*
 735                                  * Force to use the standard dynamic linker in stand-alone mode.
 736                                  * It will fails at runtime if support is not actually available
 737                                  */
 738                                 execle(TRUSTED_LDSO, TRUSTED_LDSO, filename, NULL, envp);
 739                                 _exit(0xdead);
 740                         }
 741 #else
 742                         if ((pid = vfork()) == 0) {
 743                                 /* Cool, it looks like we should be able to actually
 744                                  * run this puppy.  Do so now... */
 745                                 execle(filename, filename, NULL, environment);
 746                                 _exit(0xdead);
 747                         }
 748 #endif
 749                         /* Wait till it returns */
 750                         waitpid(pid, &status, 0);
 751
 752 #ifdef __LDSO_STANDALONE_SUPPORT__
 753                         /* Do not leak */
 754                         free(lib_path);
 755 #endif
 756
 757                         if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
 758                                 return 1;
 759                         }
 760
 761                         /* If the exec failed, we fall through to trying to find
 762                          * all the needed libraries ourselves by rummaging about
 763                          * in the ELF headers... */
 764                 }
 765         }
 766 #endif
 767
 768         dynsec = elf_find_section_type(SHT_DYNAMIC, ehdr);
 769         if (dynsec) {
 770                 dynamic = (ElfW(Dyn) *) (byteswap_to_host(dynsec->sh_offset) + (char *)ehdr);
 771                 find_needed_libraries(ehdr, dynamic, is_suid);
 772         }
 773
 774         return 0;
 775 }
 776
 777 int main(int argc, char **argv)
 778 {
 779         int multi = 0;
 780         int got_em_all = 1;
 781         char *filename = NULL;
 782         struct library *cur;
 783
 784         if (argc < 2) {
 785                 fprintf(stderr, "ldd: missing file arguments\n"
 786                                 "Try `ldd --help' for more information.\n");
 787                 exit(EXIT_FAILURE);
 788         }
 789         if (argc > 2)
 790                 multi++;
 791
 792         while (--argc > 0) {
 793                 ++argv;
 794
 795                 if (strcmp(*argv, "--") == 0) {
 796                         /* Ignore "--" */
 797                         continue;
 798                 }
 799
 800                 if (strcmp(*argv, "--help") == 0 || strcmp(*argv, "-h") == 0) {
 801                         fprintf(stderr, "Usage: ldd [OPTION]... FILE...\n"
 802                                         "\t--help\t\tprint this help and exit\n");
 803                         exit(EXIT_SUCCESS);
 804                 }
 805
 806                 filename = *argv;
 807                 if (!filename) {
 808                         fprintf(stderr, "No filename specified.\n");
 809                         exit(EXIT_FAILURE);
 810                 }
 811
 812                 if (multi) {
 813                         printf("%s:\n", *argv);
 814                 }
 815
 816                 map_cache();
 817
 818                 if (find_dependencies(filename) != 0)
 819                         continue;
 820
 821                 while (got_em_all) {
 822                         got_em_all = 0;
 823                         /* Keep walking the list till everybody is resolved */
 824                         for (cur = lib_list; cur; cur = cur->next) {
 825                                 if (cur->resolved == 0 && cur->path) {
 826                                         got_em_all = 1;
 827                                         printf("checking sub-depends for '%s'\n", cur->path);
 828                                         find_dependencies(cur->path);
 829                                         cur->resolved = 1;
 830                                 }
 831                         }
 832                 }
 833
 834                 unmap_cache();
 835
 836                 /* Print the list */
 837                 got_em_all = 0;
 838                 for (cur = lib_list; cur; cur = cur->next) {
 839                         got_em_all = 1;
 840                         printf("\t%s => %s (0x00000000)\n", cur->name, cur->path);
 841                 }
 842                 if (interp_name && interpreter_already_found == 1)
 843                         printf("\t%s => %s (0x00000000)\n", interp_name, interp_name);
 844                 else
 845                         printf("\tnot a dynamic executable\n");
 846
 847                 for (cur = lib_list; cur; cur = cur->next) {
 848                         free(cur->name);
 849                         cur->name = NULL;
 850                         if (cur->path && cur->path != not_found) {
 851                                 free(cur->path);
 852                                 cur->path = NULL;
 853                         }
 854                 }
 855                 lib_list = NULL;
 856         }
 857
 858         return 0;
 859 }