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(__arc__)
  24 #define MATCH_MACHINE(x) (x == EM_ARCOMPACT)
  25 #define ELFCLASSM      ELFCLASS32
  26 #endif
  27
  28 #if defined(__arm__) || defined(__thumb__)
  29 #define MATCH_MACHINE(x) (x == EM_ARM)
  30 #define ELFCLASSM       ELFCLASS32
  31 #endif
  32
  33 #if defined(__avr32__)
  34 #define MATCH_MACHINE(x) (x == EM_AVR32)
  35 #define ELFCLASSM      ELFCLASS32
  36 #endif
  37
  38 #if defined(__bfin__)
  39 #define MATCH_MACHINE(x) (x == EM_BLACKFIN)
  40 #define ELFCLASSM      ELFCLASS32
  41 #endif
  42
  43 #if defined(__s390__)
  44 #define MATCH_MACHINE(x) (x == EM_S390)
  45 #define ELFCLASSM       ELFCLASS32
  46 #endif
  47
  48 #if defined(__hppa__)
  49 #define MATCH_MACHINE(x) (x == EM_PARISC)
  50 #if defined(__LP64__)
  51 #define ELFCLASSM               ELFCLASS64
  52 #else
  53 #define ELFCLASSM               ELFCLASS32
  54 #endif
  55 #endif
  56
  57 #if defined(__i386__)
  58 #ifndef EM_486
  59 #define MATCH_MACHINE(x) (x == EM_386)
  60 #else
  61 #define MATCH_MACHINE(x) (x == EM_386 || x == EM_486)
  62 #endif
  63 #define ELFCLASSM       ELFCLASS32
  64 #endif
  65
  66 #if defined(__ia64__)
  67 #define MATCH_MACHINE(x) (x == EM_IA_64)
  68 #define ELFCLASSM       ELFCLASS64
  69 #endif
  70
  71 #if defined(__mc68000__)
  72 #define MATCH_MACHINE(x) (x == EM_68K)
  73 #define ELFCLASSM       ELFCLASS32
  74 #endif
  75
  76 #if defined(__metag__)
  77 #define MATCH_MACHINE(x) (x == EM_METAG)
  78 #define ELFCLASSM       ELFCLASS32
  79 #endif
  80
  81 #if defined(__mips__)
  82 #define MATCH_MACHINE(x) (x == EM_MIPS || x == EM_MIPS_RS3_LE)
  83 #define ELFCLASSM       ELFCLASS32
  84 #endif
  85
  86 #if defined(__powerpc64__)
  87 #define MATCH_MACHINE(x) (x == EM_PPC64)
  88 #define ELFCLASSM       ELFCLASS64
  89 #elif defined(__powerpc__)
  90 #define MATCH_MACHINE(x) (x == EM_PPC)
  91 #define ELFCLASSM       ELFCLASS32
  92 #endif
  93
  94 #if defined(__sh__)
  95 #define MATCH_MACHINE(x) (x == EM_SH)
  96 #define ELFCLASSM       ELFCLASS32
  97 #endif
  98
  99 #if defined(__sparc__)
 100 #define MATCH_MACHINE(x) ((x) == EM_SPARC || (x) == EM_SPARC32PLUS)
 101 #define ELFCLASSM    ELFCLASS32
 102 #endif
 103
 104 #if defined(__cris__)
 105 #define MATCH_MACHINE(x) (x == EM_CRIS)
 106 #define ELFCLASSM       ELFCLASS32
 107 #endif
 108
 109 #if defined(__x86_64__)
 110 #define MATCH_MACHINE(x) (x == EM_X86_64)
 111 #define ELFCLASSM       ELFCLASS64
 112 #endif
 113
 114 #if defined(__microblaze__)
 115 #define MATCH_MACHINE(x) (x == EM_MICROBLAZE)
 116 #define ELFCLASSM       ELFCLASS32
 117 #endif
 118
 119 #if defined(__xtensa__)
 120 #define MATCH_MACHINE(x) (x == EM_XTENSA)
 121 #define ELFCLASSM       ELFCLASS32
 122 #endif
 123
 124 #ifndef MATCH_MACHINE
 125 # ifdef __linux__
 126 #  include <asm/elf.h>
 127 # endif
 128 # ifdef ELF_ARCH
 129 #  define MATCH_MACHINE(x) (x == ELF_ARCH)
 130 # endif
 131 # ifdef ELF_CLASS
 132 #  define ELFCLASSM ELF_CLASS
 133 # endif
 134 #endif
 135 #ifndef MATCH_MACHINE
 136 # warning "You really should add a MATCH_MACHINE() macro for your architecture"
 137 #endif
 138
 139 #if UCLIBC_ENDIAN_HOST == UCLIBC_ENDIAN_LITTLE
 140 #define ELFDATAM        ELFDATA2LSB
 141 #elif UCLIBC_ENDIAN_HOST == UCLIBC_ENDIAN_BIG
 142 #define ELFDATAM        ELFDATA2MSB
 143 #endif
 144
 145 #define TRUSTED_LDSO    UCLIBC_RUNTIME_PREFIX "lib/" UCLIBC_LDSO
 146
 147 struct library {
 148         char *name;
 149         int resolved;
 150         char *path;
 151         struct library *next;
 152 };
 153 static struct library *lib_list = NULL;
 154 static char not_found[] = "not found";
 155 static char *interp_name = NULL;
 156 static char *interp_dir = NULL;
 157 static int byteswap;
 158 static int interpreter_already_found = 0;
 159
 160 static __inline__ uint32_t byteswap32_to_host(uint32_t value)
 161 {
 162         if (byteswap) {
 163                 return (bswap_32(value));
 164         } else {
 165                 return (value);
 166         }
 167 }
 168 static __inline__ uint64_t byteswap64_to_host(uint64_t value)
 169 {
 170         if (byteswap) {
 171                 return (bswap_64(value));
 172         } else {
 173                 return (value);
 174         }
 175 }
 176
 177 #if __WORDSIZE == 64
 178 # define byteswap_to_host(x) byteswap64_to_host(x)
 179 #else
 180 # define byteswap_to_host(x) byteswap32_to_host(x)
 181 #endif
 182
 183 static ElfW(Shdr) *elf_find_section_type(uint32_t key, ElfW(Ehdr) *ehdr)
 184 {
 185         int j;
 186         ElfW(Shdr) *shdr;
 187         shdr = (ElfW(Shdr) *) (ehdr->e_shoff + (char *)ehdr);
 188         for (j = ehdr->e_shnum; --j >= 0; ++shdr) {
 189                 if (key == byteswap32_to_host(shdr->sh_type)) {
 190                         return shdr;
 191                 }
 192         }
 193         return NULL;
 194 }
 195
 196 static ElfW(Phdr) *elf_find_phdr_type(uint32_t type, ElfW(Ehdr) *ehdr)
 197 {
 198         int j;
 199         ElfW(Phdr) *phdr = (ElfW(Phdr) *) (ehdr->e_phoff + (char *)ehdr);
 200         for (j = ehdr->e_phnum; --j >= 0; ++phdr) {
 201                 if (type == byteswap32_to_host(phdr->p_type)) {
 202                         return phdr;
 203                 }
 204         }
 205         return NULL;
 206 }
 207
 208 /* Returns value if return_val==1, ptr otherwise */
 209 static void *elf_find_dynamic(int64_t const key, ElfW(Dyn) *dynp,
 210                        ElfW(Ehdr) *ehdr, int return_val)
 211 {
 212         ElfW(Phdr) *pt_text = elf_find_phdr_type(PT_LOAD, ehdr);
 213         unsigned tx_reloc = byteswap_to_host(pt_text->p_vaddr) - byteswap_to_host(pt_text->p_offset);
 214         for (; DT_NULL != byteswap_to_host(dynp->d_tag); ++dynp) {
 215                 if (key == byteswap_to_host(dynp->d_tag)) {
 216                         if (return_val == 1)
 217                                 return (void *)byteswap_to_host(dynp->d_un.d_val);
 218                         else
 219                                 return (void *)(byteswap_to_host(dynp->d_un.d_val) - tx_reloc + (char *)ehdr);
 220                 }
 221         }
 222         return NULL;
 223 }
 224
 225 static char *elf_find_rpath(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic)
 226 {
 227         ElfW(Dyn) *dyns;
 228
 229         for (dyns = dynamic; byteswap_to_host(dyns->d_tag) != DT_NULL; ++dyns) {
 230                 if (DT_RPATH == byteswap_to_host(dyns->d_tag)) {
 231                         char *strtab;
 232                         strtab = (char *)elf_find_dynamic(DT_STRTAB, dynamic, ehdr, 0);
 233                         return ((char *)strtab + byteswap_to_host(dyns->d_un.d_val));
 234                 }
 235         }
 236         return NULL;
 237 }
 238
 239 static int check_elf_header(ElfW(Ehdr) *const ehdr)
 240 {
 241         if (!ehdr || *(uint32_t*)ehdr != ELFMAG_U32
 242          /* Use __WORDSIZE, not ELFCLASSM which depends on the host */
 243          || ehdr->e_ident[EI_CLASS] != (__WORDSIZE >> 5)
 244          || ehdr->e_ident[EI_VERSION] != EV_CURRENT
 245         ) {
 246                 return 1;
 247         }
 248
 249         /* Check if the target endianness matches the host's endianness */
 250         byteswap = !(ehdr->e_ident[5] == ELFDATAM);
 251
 252         /* Be very lazy, and only byteswap the stuff we use */
 253         if (byteswap) {
 254                 ehdr->e_type = bswap_16(ehdr->e_type);
 255                 ehdr->e_phoff = byteswap_to_host(ehdr->e_phoff);
 256                 ehdr->e_shoff = byteswap_to_host(ehdr->e_shoff);
 257                 ehdr->e_phnum = bswap_16(ehdr->e_phnum);
 258                 ehdr->e_shnum = bswap_16(ehdr->e_shnum);
 259         }
 260
 261         return 0;
 262 }
 263
 264 #ifdef __LDSO_CACHE_SUPPORT__
 265 static caddr_t cache_addr = NULL;
 266 static size_t cache_size = 0;
 267
 268 static int map_cache(void)
 269 {
 270         int fd;
 271         struct stat st;
 272         header_t *header;
 273         libentry_t *libent;
 274         int i, strtabsize;
 275
 276         if (cache_addr == (caddr_t) - 1)
 277                 return -1;
 278         else if (cache_addr != NULL)
 279                 return 0;
 280
 281         if (stat(LDSO_CACHE, &st) || (fd = open(LDSO_CACHE, O_RDONLY)) < 0) {
 282                 fprintf(stderr, "ldd: can't open cache '%s'\n", LDSO_CACHE);
 283                 cache_addr = (caddr_t) - 1;     /* so we won't try again */
 284                 return -1;
 285         }
 286
 287         cache_size = st.st_size;
 288         cache_addr = mmap(0, cache_size, PROT_READ, MAP_SHARED, fd, 0);
 289         close(fd);
 290         if (cache_addr == MAP_FAILED) {
 291                 fprintf(stderr, "ldd: can't map cache '%s'\n", LDSO_CACHE);
 292                 return -1;
 293         }
 294
 295         header = (header_t *) cache_addr;
 296
 297         if (cache_size < sizeof(header_t)
 298             || memcmp(header->magic, LDSO_CACHE_MAGIC, LDSO_CACHE_MAGIC_LEN)
 299             || memcmp(header->version, LDSO_CACHE_VER, LDSO_CACHE_VER_LEN)
 300             || cache_size < (sizeof(header_t) + header->nlibs * sizeof(libentry_t))
 301             || cache_addr[cache_size - 1] != '\0')
 302         {
 303                 fprintf(stderr, "ldd: cache '%s' is corrupt\n", LDSO_CACHE);
 304                 goto fail;
 305         }
 306
 307         strtabsize = cache_size - sizeof(header_t) - header->nlibs * sizeof(libentry_t);
 308         libent = (libentry_t *) & header[1];
 309
 310         for (i = 0; i < header->nlibs; i++) {
 311                 if (libent[i].sooffset >= strtabsize || libent[i].liboffset >= strtabsize) {
 312                         fprintf(stderr, "ldd: cache '%s' is corrupt\n", LDSO_CACHE);
 313                         goto fail;
 314                 }
 315         }
 316
 317         return 0;
 318
 319 fail:
 320         munmap(cache_addr, cache_size);
 321         cache_addr = (caddr_t) - 1;
 322         return -1;
 323 }
 324
 325 static int unmap_cache(void)
 326 {
 327         if (cache_addr == NULL || cache_addr == (caddr_t) - 1)
 328                 return -1;
 329
 330 #if 1
 331         munmap(cache_addr, cache_size);
 332         cache_addr = NULL;
 333 #endif
 334
 335         return 0;
 336 }
 337 #else
 338 static __inline__ void map_cache(void)
 339 {
 340 }
 341 static __inline__ void unmap_cache(void)
 342 {
 343 }
 344 #endif
 345
 346 /* This function's behavior must exactly match that
 347  * in uClibc/ldso/ldso/dl-elf.c */
 348 static void search_for_named_library(char *name, char *result,
 349                                      const char *path_list)
 350 {
 351         int i, count = 1;
 352         char *path, *path_n;
 353         struct stat filestat;
 354
 355         /* We need a writable copy of this string */
 356         path = strdup(path_list);
 357         if (!path) {
 358                 fprintf(stderr, "%s: Out of memory!\n", __func__);
 359                 exit(EXIT_FAILURE);
 360         }
 361         /* Eliminate all double //s */
 362         path_n = path;
 363         while ((path_n = strstr(path_n, "//"))) {
 364                 i = strlen(path_n);
 365                 memmove(path_n, path_n + 1, i - 1);
 366                 *(path_n + i - 1) = '\0';
 367         }
 368
 369         /* Replace colons with zeros in path_list and count them */
 370         for (i = strlen(path); i > 0; i--) {
 371                 if (path[i] == ':') {
 372                         path[i] = 0;
 373                         count++;
 374                 }
 375         }
 376         path_n = path;
 377         for (i = 0; i < count; i++) {
 378                 strcpy(result, path_n);
 379                 strcat(result, "/");
 380                 strcat(result, name);
 381                 if (stat(result, &filestat) == 0 && filestat.st_mode & S_IRUSR) {
 382                         free(path);
 383                         return;
 384                 }
 385                 path_n += (strlen(path_n) + 1);
 386         }
 387         free(path);
 388         *result = '\0';
 389 }
 390
 391 static void locate_library_file(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic,
 392                                 int is_suid, struct library *lib)
 393 {
 394         char *buf;
 395         char *path;
 396         struct stat filestat;
 397
 398         /* If this is a fully resolved name, our job is easy */
 399         if (stat(lib->name, &filestat) == 0) {
 400                 lib->path = strdup(lib->name);
 401                 return;
 402         }
 403
 404         /* We need some elbow room here.  Make some room... */
 405         buf = malloc(1024);
 406         if (!buf) {
 407                 fprintf(stderr, "%s: Out of memory!\n", __func__);
 408                 exit(EXIT_FAILURE);
 409         }
 410
 411         /* This function must match the behavior of _dl_load_shared_library
 412          * in readelflib1.c or things won't work out as expected... */
 413
 414         /* The ABI specifies that RPATH is searched first, so do that now.  */
 415         path = elf_find_rpath(ehdr, dynamic);
 416         if (path) {
 417                 search_for_named_library(lib->name, buf, path);
 418                 if (*buf != '\0') {
 419                         lib->path = buf;
 420                         return;
 421                 }
 422         }
 423
 424         /* Next check LD_{ELF_}LIBRARY_PATH if specified and allowed.
 425          * Since this app doesn't actually run an executable I will skip
 426          * the suid check, and just use LD_{ELF_}LIBRARY_PATH if set */
 427         if (is_suid == 1)
 428                 path = NULL;
 429         else
 430                 path = getenv("LD_LIBRARY_PATH");
 431         if (path) {
 432                 search_for_named_library(lib->name, buf, path);
 433                 if (*buf != '\0') {
 434                         lib->path = buf;
 435                         return;
 436                 }
 437         }
 438 #ifdef __LDSO_CACHE_SUPPORT__
 439         if (cache_addr != NULL && cache_addr != (caddr_t) - 1) {
 440                 int i;
 441                 header_t *header = (header_t *) cache_addr;
 442                 libentry_t *libent = (libentry_t *) & header[1];
 443                 char *strs = (char *)&libent[header->nlibs];
 444
 445                 for (i = 0; i < header->nlibs; i++) {
 446                         if ((libent[i].flags == LIB_ELF ||
 447                              libent[i].flags == LIB_ELF_LIBC0 ||
 448                              libent[i].flags == LIB_ELF_LIBC5) &&
 449                             strcmp(lib->name, strs + libent[i].sooffset) == 0)
 450                         {
 451                                 lib->path = strdup(strs + libent[i].liboffset);
 452                                 return;
 453                         }
 454                 }
 455         }
 456 #endif
 457
 458         /* Next look for libraries wherever the shared library
 459          * loader was installed -- this is usually where we
 460          * should find things... */
 461         if (interp_dir) {
 462                 search_for_named_library(lib->name, buf, interp_dir);
 463                 if (*buf != '\0') {
 464                         lib->path = buf;
 465                         return;
 466                 }
 467         }
 468
 469         /* Lastly, search the standard list of paths for the library.
 470            This list must exactly match the list in uClibc/ldso/ldso/dl-elf.c */
 471         path = UCLIBC_RUNTIME_PREFIX "lib:" UCLIBC_RUNTIME_PREFIX "usr/lib"
 472 #ifndef __LDSO_CACHE_SUPPORT__
 473             ":" UCLIBC_RUNTIME_PREFIX "usr/X11R6/lib"
 474 #endif
 475             ;
 476         search_for_named_library(lib->name, buf, path);
 477         if (*buf != '\0') {
 478                 lib->path = buf;
 479         } else {
 480                 free(buf);
 481                 lib->path = not_found;
 482         }
 483 }
 484
 485 static int add_library(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic, int is_setuid, char *s)
 486 {
 487         char *tmp, *tmp1, *tmp2;
 488         struct library *cur, *newlib = lib_list;
 489
 490         if (!s || !strlen(s))
 491                 return 1;
 492
 493         tmp = s;
 494         while (*tmp) {
 495                 if (*tmp == '/')
 496                         s = tmp + 1;
 497                 tmp++;
 498         }
 499
 500         /* We add ldso elsewhere */
 501         if (interpreter_already_found && (tmp = strrchr(interp_name, '/')) != NULL) {
 502                 int len = strlen(interp_dir);
 503                 if (strcmp(s, interp_name + 1 + len) == 0)
 504                         return 1;
 505         }
 506
 507         for (cur = lib_list; cur; cur = cur->next) {
 508                 /* Check if this library is already in the list */
 509                 tmp1 = tmp2 = cur->name;
 510                 if (!cur->name)
 511                         continue;
 512                 while (*tmp1) {
 513                         if (*tmp1 == '/')
 514                                 tmp2 = tmp1 + 1;
 515                         tmp1++;
 516                 }
 517                 if (strcmp(tmp2, s) == 0) {
 518                         /*printf("find_elf_interpreter is skipping '%s' (already in list)\n", cur->name); */
 519                         return 0;
 520                 }
 521         }
 522
 523         /* Ok, this lib needs to be added to the list */
 524         newlib = malloc(sizeof(struct library));
 525         if (!newlib)
 526                 return 1;
 527         newlib->name = malloc(strlen(s) + 1);
 528         strcpy(newlib->name, s);
 529         newlib->resolved = 0;
 530         newlib->path = NULL;
 531         newlib->next = NULL;
 532
 533         /* Now try and locate where this library might be living... */
 534         locate_library_file(ehdr, dynamic, is_setuid, newlib);
 535
 536         /*printf("add_library is adding '%s' to '%s'\n", newlib->name, newlib->path); */
 537         if (!lib_list) {
 538                 lib_list = newlib;
 539         } else {
 540                 for (cur = lib_list; cur->next; cur = cur->next) ;      /* nothing */
 541                 cur->next = newlib;
 542         }
 543         return 0;
 544 }
 545
 546 static void find_needed_libraries(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic, int is_setuid)
 547 {
 548         ElfW(Dyn) *dyns;
 549
 550         for (dyns = dynamic; byteswap_to_host(dyns->d_tag) != DT_NULL; ++dyns) {
 551                 if (DT_NEEDED == byteswap_to_host(dyns->d_tag)) {
 552                         char *strtab;
 553                         strtab = (char *)elf_find_dynamic(DT_STRTAB, dynamic, ehdr, 0);
 554                         add_library(ehdr, dynamic, is_setuid, (char *)strtab + byteswap_to_host(dyns->d_un.d_val));
 555                 }
 556         }
 557 }
 558
 559 #ifdef __LDSO_LDD_SUPPORT__
 560 static struct library *find_elf_interpreter(ElfW(Ehdr) *ehdr)
 561 {
 562         ElfW(Phdr) *phdr;
 563
 564         if (interpreter_already_found == 1)
 565                 return NULL;
 566         phdr = elf_find_phdr_type(PT_INTERP, ehdr);
 567         if (phdr) {
 568                 struct library *cur, *newlib = NULL;
 569                 char *s = (char *)ehdr + byteswap_to_host(phdr->p_offset);
 570
 571                 char *tmp, *tmp1;
 572                 interp_name = strdup(s);
 573                 interp_dir = strdup(s);
 574                 tmp = strrchr(interp_dir, '/');
 575                 if (tmp)
 576                         *tmp = '\0';
 577                 else {
 578                         free(interp_dir);
 579                         interp_dir = interp_name;
 580                 }
 581                 tmp1 = tmp = s;
 582                 while (*tmp) {
 583                         if (*tmp == '/')
 584                                 tmp1 = tmp + 1;
 585                         tmp++;
 586                 }
 587                 for (cur = lib_list; cur; cur = cur->next) {
 588                         /* Check if this library is already in the list */
 589                         if (!tmp1 || !cur->name)
 590                                 return NULL;
 591                         if (strcmp(cur->name, tmp1) == 0) {
 592                                 /*printf("find_elf_interpreter is replacing '%s' (already in list)\n", cur->name); */
 593                                 newlib = cur;
 594                                 free(newlib->name);
 595                                 if (newlib->path != not_found) {
 596                                         free(newlib->path);
 597                                 }
 598                                 newlib->name = NULL;
 599                                 newlib->path = NULL;
 600                                 break;
 601                         }
 602                 }
 603                 if (newlib == NULL)
 604                         newlib = malloc(sizeof(struct library));
 605                 if (!newlib)
 606                         return NULL;
 607                 newlib->name = malloc(strlen(s) + 1);
 608                 strcpy(newlib->name, s);
 609                 newlib->path = strdup(newlib->name);
 610                 newlib->resolved = 1;
 611                 newlib->next = NULL;
 612
 613 #if 0
 614                 /*printf("find_elf_interpreter is adding '%s' to '%s'\n", newlib->name, newlib->path); */
 615                 if (!lib_list) {
 616                         lib_list = newlib;
 617                 } else {
 618                         for (cur = lib_list; cur->next; cur = cur->next) ;      /* nothing */
 619                         cur->next = newlib;
 620                 }
 621 #endif
 622                 interpreter_already_found = 1;
 623                 return newlib;
 624         }
 625         return NULL;
 626 }
 627 #endif /* __LDSO_LDD_SUPPORT__ */
 628
 629 /* map the .so, and locate interesting pieces */
 630 /*
 631 #warning "There may be two warnings here about vfork() clobbering, ignore them"
 632 */
 633 static int find_dependencies(char *filename)
 634 {
 635         int is_suid = 0;
 636         FILE *thefile;
 637         struct stat statbuf;
 638         ElfW(Ehdr) *ehdr = NULL;
 639         ElfW(Shdr) *dynsec = NULL;
 640         ElfW(Dyn) *dynamic = NULL;
 641 #ifdef __LDSO_LDD_SUPPORT__
 642         struct library *interp;
 643 #endif
 644
 645         if (filename == not_found)
 646                 return 0;
 647
 648         if (!filename) {
 649                 fprintf(stderr, "No filename specified.\n");
 650                 return -1;
 651         }
 652         if (!(thefile = fopen(filename, "r"))) {
 653                 perror(filename);
 654                 return -1;
 655         }
 656         if (fstat(fileno(thefile), &statbuf) < 0) {
 657                 perror(filename);
 658                 fclose(thefile);
 659                 return -1;
 660         }
 661
 662         if ((size_t) statbuf.st_size < sizeof(ElfW(Ehdr)))
 663                 goto foo;
 664
 665         if (!S_ISREG(statbuf.st_mode))
 666                 goto foo;
 667
 668         /* mmap the file to make reading stuff from it effortless */
 669         ehdr = mmap(0, statbuf.st_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fileno(thefile), 0);
 670         if (ehdr == MAP_FAILED) {
 671                 fclose(thefile);
 672                 fprintf(stderr, "mmap(%s) failed: %s\n", filename, strerror(errno));
 673                 return -1;
 674         }
 675
 676 foo:
 677         fclose(thefile);
 678
 679         /* Check if this looks like a legit ELF file */
 680         if (check_elf_header(ehdr)) {
 681                 fprintf(stderr, "%s: not an ELF file.\n", filename);
 682                 return -1;
 683         }
 684         /* Check if this is the right kind of ELF file */
 685         if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) {
 686                 fprintf(stderr, "%s: not a dynamic executable\n", filename);
 687                 return -1;
 688         }
 689         if (ehdr->e_type == ET_EXEC || ehdr->e_type == ET_DYN) {
 690                 if (statbuf.st_mode & S_ISUID)
 691                         is_suid = 1;
 692                 if ((statbuf.st_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP))
 693                         is_suid = 1;
 694                 /* FIXME */
 695                 if (is_suid)
 696                         fprintf(stderr, "%s: is setuid\n", filename);
 697         }
 698
 699         interpreter_already_found = 0;
 700 #ifdef __LDSO_LDD_SUPPORT__
 701         interp = find_elf_interpreter(ehdr);
 702
 703         if (interp
 704             && (ehdr->e_type == ET_EXEC || ehdr->e_type == ET_DYN)
 705             && ehdr->e_ident[EI_CLASS] == ELFCLASSM
 706             && ehdr->e_ident[EI_DATA] == ELFDATAM
 707             && ehdr->e_ident[EI_VERSION] == EV_CURRENT
 708             && MATCH_MACHINE(ehdr->e_machine))
 709         {
 710                 struct stat st;
 711                 if (stat(interp->path, &st) == 0 && S_ISREG(st.st_mode)) {
 712                         pid_t pid;
 713                         int status;
 714                         static const char *const environment[] = {
 715                                 "PATH=/usr/bin:/bin:/usr/sbin:/sbin",
 716                                 "SHELL=/bin/sh",
 717                                 "LD_TRACE_LOADED_OBJECTS=1",
 718                                 NULL
 719                         };
 720 # ifdef __LDSO_STANDALONE_SUPPORT__
 721                         char * lib_path = getenv("LD_LIBRARY_PATH");
 722
 723                         /* The 'extended' environment inclusing the LD_LIBRARY_PATH */
 724                         static char *ext_environment[ARRAY_SIZE(environment) + 1];
 725                         char **envp = (char **) environment;
 726
 727                         if (lib_path) {
 728                                 /*
 729                                  * If the LD_LIBRARY_PATH is set, it needs to include it
 730                                  * into the environment for the new process to be spawned
 731                                  */
 732                                 char ** eenvp = (char **) ext_environment;
 733
 734                                 /* Copy the N-1 environment's entries */
 735                                 while (*envp)
 736                                         *eenvp++=*envp++;
 737
 738                                 /* Make room for LD_LIBRARY_PATH */
 739                                 *eenvp = (char *) malloc(sizeof("LD_LIBRARY_PATH=")
 740                                                                           + strlen(lib_path));
 741                                 strcpy(*eenvp, "LD_LIBRARY_PATH=");
 742                                 strcat(*eenvp, lib_path);
 743                                 lib_path = *eenvp;
 744                                 /* ext_environment[size] is already NULL */
 745
 746                                 /* Use the extended environment */
 747                                 envp = ext_environment;
 748                         }
 749                         if ((pid = vfork()) == 0) {
 750                                 /*
 751                                  * Force to use the standard dynamic linker in stand-alone mode.
 752                                  * It will fails at runtime if support is not actually available
 753                                  */
 754                                 execle(TRUSTED_LDSO, TRUSTED_LDSO, filename, NULL, envp);
 755                                 _exit(0xdead);
 756                         }
 757 # else
 758                         if ((pid = vfork()) == 0) {
 759                                 /* Cool, it looks like we should be able to actually
 760                                  * run this puppy.  Do so now... */
 761                                 execle(filename, filename, NULL, environment);
 762                                 _exit(0xdead);
 763                         }
 764 # endif
 765                         /* Wait till it returns */
 766                         waitpid(pid, &status, 0);
 767
 768 # ifdef __LDSO_STANDALONE_SUPPORT__
 769                         /* Do not leak */
 770                         free(lib_path);
 771 # endif
 772
 773                         if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
 774                                 return 1;
 775                         }
 776
 777                         /* If the exec failed, we fall through to trying to find
 778                          * all the needed libraries ourselves by rummaging about
 779                          * in the ELF headers... */
 780                 }
 781         }
 782 #endif
 783
 784         dynsec = elf_find_section_type(SHT_DYNAMIC, ehdr);
 785         if (dynsec) {
 786                 dynamic = (ElfW(Dyn) *) (byteswap_to_host(dynsec->sh_offset) + (char *)ehdr);
 787                 find_needed_libraries(ehdr, dynamic, is_suid);
 788         }
 789
 790         return 0;
 791 }
 792
 793 int main(int argc, char **argv)
 794 {
 795         int multi = 0;
 796         int got_em_all = 1;
 797         char *filename = NULL;
 798         struct library *cur;
 799
 800         if (argc < 2) {
 801                 fprintf(stderr, "ldd: missing file arguments\n"
 802                                 "Try `ldd --help' for more information.\n");
 803                 exit(EXIT_FAILURE);
 804         }
 805         if (argc > 2)
 806                 multi++;
 807
 808         while (--argc > 0) {
 809                 ++argv;
 810
 811                 if (strcmp(*argv, "--") == 0) {
 812                         /* Ignore "--" */
 813                         continue;
 814                 }
 815
 816                 if (strcmp(*argv, "--help") == 0 || strcmp(*argv, "-h") == 0) {
 817                         fprintf(stderr, "Usage: ldd [OPTION]... FILE...\n"
 818                                         "\t--help\t\tprint this help and exit\n");
 819                         exit(EXIT_SUCCESS);
 820                 }
 821
 822                 filename = *argv;
 823                 if (!filename) {
 824                         fprintf(stderr, "No filename specified.\n");
 825                         exit(EXIT_FAILURE);
 826                 }
 827
 828                 if (multi) {
 829                         printf("%s:\n", *argv);
 830                 }
 831
 832                 map_cache();
 833
 834                 if (find_dependencies(filename) != 0)
 835                         continue;
 836
 837                 while (got_em_all) {
 838                         got_em_all = 0;
 839                         /* Keep walking the list till everybody is resolved */
 840                         for (cur = lib_list; cur; cur = cur->next) {
 841                                 if (cur->resolved == 0 && cur->path) {
 842                                         got_em_all = 1;
 843                                         printf("checking sub-depends for '%s'\n", cur->path);
 844                                         find_dependencies(cur->path);
 845                                         cur->resolved = 1;
 846                                 }
 847                         }
 848                 }
 849
 850                 unmap_cache();
 851
 852                 /* Print the list */
 853                 got_em_all = 0;
 854                 for (cur = lib_list; cur; cur = cur->next) {
 855                         got_em_all = 1;
 856                         printf("\t%s => %s (0x00000000)\n", cur->name, cur->path);
 857                 }
 858                 if (interp_name && interpreter_already_found == 1)
 859                         printf("\t%s => %s (0x00000000)\n", interp_name, interp_name);
 860                 else
 861                         printf("\tnot a dynamic executable\n");
 862
 863                 for (cur = lib_list; cur; cur = cur->next) {
 864                         free(cur->name);
 865                         cur->name = NULL;
 866                         if (cur->path && cur->path != not_found) {
 867                                 free(cur->path);
 868                                 cur->path = NULL;
 869                         }
 870                 }
 871                 lib_list = NULL;
 872         }
 873
 874         return 0;
 875 }