utils/ldd.c

   1 /*
   2  * A small little ldd implementation for uClibc
   3  *
   4  * Copyright (C) 2000-2006 Erik Andersen <andersen@uclibc.org>
   5  *
   6  * Several functions in this file (specifically, elf_find_section_type(),
   7  * elf_find_phdr_type(), and elf_find_dynamic(), were stolen from elflib.c from
   8  * elfvector (http://www.BitWagon.com/elfvector.html) by John F. Reiser
   9  * <jreiser@BitWagon.com>, which is copyright 2000 BitWagon Software LLC
  10  * (GPL2).
  11  *
  12  * Licensed under GPLv2 or later
  13  */
  14
  15 #include "porting.h"
  16
  17 #if defined(__aarch64__)
  18 #define MATCH_MACHINE(x) (x == EM_AARCH64)
  19 #define ELFCLASSM       ELFCLASS64
  20 #endif
  21
  22 #if defined(__alpha__)
  23 #define MATCH_MACHINE(x) (x == EM_ALPHA)
  24 #define ELFCLASSM       ELFCLASS64
  25 #endif
  26
  27 #if defined(__arc__)
  28 #define MATCH_MACHINE(x) (x == EM_ARCOMPACT)
  29 #define ELFCLASSM      ELFCLASS32
  30 #endif
  31
  32 #if defined(__arm__) || defined(__thumb__)
  33 #define MATCH_MACHINE(x) (x == EM_ARM)
  34 #define ELFCLASSM       ELFCLASS32
  35 #endif
  36
  37 #if defined(__avr32__)
  38 #define MATCH_MACHINE(x) (x == EM_AVR32)
  39 #define ELFCLASSM      ELFCLASS32
  40 #endif
  41
  42 #if defined(__bfin__)
  43 #define MATCH_MACHINE(x) (x == EM_BLACKFIN)
  44 #define ELFCLASSM      ELFCLASS32
  45 #endif
  46
  47 #if defined(__TMS320C6X__)
  48 #define MATCH_MACHINE(x) (x == EM_TI_C6000)
  49 #define ELFCLASSM       ELFCLASS32
  50 #endif
  51
  52 #if defined(__cris__)
  53 #define MATCH_MACHINE(x) (x == EM_CRIS)
  54 #define ELFCLASSM       ELFCLASS32
  55 #endif
  56
  57 #if defined(__frv__)
  58 #define MATCH_MACHINE(x) (x == EM_CYGNUS_FRV)
  59 #define ELFCLASSM       ELFCLASS32
  60 #endif
  61
  62 #if defined(__hppa__)
  63 #define MATCH_MACHINE(x) (x == EM_PARISC)
  64 #if defined(__LP64__)
  65 #define ELFCLASSM               ELFCLASS64
  66 #else
  67 #define ELFCLASSM               ELFCLASS32
  68 #endif
  69 #endif
  70
  71 #if defined(__i386__)
  72 #ifndef EM_486
  73 #define MATCH_MACHINE(x) (x == EM_386)
  74 #else
  75 #define MATCH_MACHINE(x) (x == EM_386 || x == EM_486)
  76 #endif
  77 #define ELFCLASSM       ELFCLASS32
  78 #endif
  79
  80 #if defined(__ia64__)
  81 #define MATCH_MACHINE(x) (x == EM_IA_64)
  82 #define ELFCLASSM       ELFCLASS64
  83 #endif
  84
  85 #if defined(__mc68000__)
  86 #define MATCH_MACHINE(x) (x == EM_68K)
  87 #define ELFCLASSM       ELFCLASS32
  88 #endif
  89
  90 #if defined(__metag__)
  91 #define MATCH_MACHINE(x) (x == EM_METAG)
  92 #define ELFCLASSM       ELFCLASS32
  93 #endif
  94
  95 #if defined(__microblaze__)
  96 #define MATCH_MACHINE(x) (x == EM_MICROBLAZE)
  97 #define ELFCLASSM       ELFCLASS32
  98 #endif
  99
 100 #if defined(__mips__)
 101 #define MATCH_MACHINE(x) (x == EM_MIPS || x == EM_MIPS_RS3_LE)
 102 #define ELFCLASSM       ELFCLASS32
 103 #endif
 104
 105 #if defined(__nds32__)
 106 #define MATCH_MACHINE(x) (x == EM_NDS32)
 107 #define ELFCLASSM       ELFCLASS32
 108 #endif
 109
 110 #if defined(__nios2__)
 111 #define MATCH_MACHINE(x) (x == EM_NIOS32)
 112 #define ELFCLASSM       ELFCLASS32
 113 #endif
 114
 115 #if defined(__powerpc__)
 116 #define MATCH_MACHINE(x) (x == EM_PPC)
 117 #define ELFCLASSM       ELFCLASS32
 118 #endif
 119
 120 #if defined(__sh__)
 121 #define MATCH_MACHINE(x) (x == EM_SH)
 122 #define ELFCLASSM       ELFCLASS32
 123 #endif
 124
 125 #if defined(__sparc__)
 126 #define MATCH_MACHINE(x) ((x) == EM_SPARC || (x) == EM_SPARC32PLUS)
 127 #define ELFCLASSM    ELFCLASS32
 128 #endif
 129
 130 #if defined(__x86_64__)
 131 #define MATCH_MACHINE(x) (x == EM_X86_64)
 132 #define ELFCLASSM       ELFCLASS64
 133 #endif
 134
 135 #if defined(__xtensa__)
 136 #define MATCH_MACHINE(x) (x == EM_XTENSA)
 137 #define ELFCLASSM       ELFCLASS32
 138 #endif
 139
 140 #ifndef MATCH_MACHINE
 141 # ifdef __linux__
 142 #  include <asm/elf.h>
 143 # endif
 144 # ifdef ELF_ARCH
 145 #  define MATCH_MACHINE(x) (x == ELF_ARCH)
 146 # endif
 147 # ifdef ELF_CLASS
 148 #  define ELFCLASSM ELF_CLASS
 149 # endif
 150 #endif
 151 #ifndef MATCH_MACHINE
 152 # warning "You really should add a MATCH_MACHINE() macro for your architecture"
 153 #endif
 154
 155 #if UCLIBC_ENDIAN_HOST == UCLIBC_ENDIAN_LITTLE
 156 #define ELFDATAM        ELFDATA2LSB
 157 #elif UCLIBC_ENDIAN_HOST == UCLIBC_ENDIAN_BIG
 158 #define ELFDATAM        ELFDATA2MSB
 159 #endif
 160
 161 #define TRUSTED_LDSO    UCLIBC_RUNTIME_PREFIX "lib/" UCLIBC_LDSO
 162
 163 struct library {
 164         char *name;
 165         int resolved;
 166         char *path;
 167         struct library *next;
 168 };
 169 static struct library *lib_list = NULL;
 170 static char not_found[] = "not found";
 171 static char *interp_name = NULL;
 172 static char *interp_dir = NULL;
 173 static int byteswap;
 174 static int interpreter_already_found = 0;
 175
 176 static __inline__ uint32_t byteswap32_to_host(uint32_t value)
 177 {
 178         if (byteswap) {
 179                 return (bswap_32(value));
 180         } else {
 181                 return (value);
 182         }
 183 }
 184 static __inline__ uint64_t byteswap64_to_host(uint64_t value)
 185 {
 186         if (byteswap) {
 187                 return (bswap_64(value));
 188         } else {
 189                 return (value);
 190         }
 191 }
 192
 193 #if __WORDSIZE == 64
 194 # define byteswap_to_host(x) byteswap64_to_host(x)
 195 #else
 196 # define byteswap_to_host(x) byteswap32_to_host(x)
 197 #endif
 198
 199 static ElfW(Shdr) *elf_find_section_type(uint32_t key, ElfW(Ehdr) *ehdr)
 200 {
 201         int j;
 202         ElfW(Shdr) *shdr;
 203         shdr = (ElfW(Shdr) *) (ehdr->e_shoff + (char *)ehdr);
 204         for (j = ehdr->e_shnum; --j >= 0; ++shdr) {
 205                 if (key == byteswap32_to_host(shdr->sh_type)) {
 206                         return shdr;
 207                 }
 208         }
 209         return NULL;
 210 }
 211
 212 static ElfW(Phdr) *elf_find_phdr_type(uint32_t type, ElfW(Ehdr) *ehdr)
 213 {
 214         int j;
 215         ElfW(Phdr) *phdr = (ElfW(Phdr) *) (ehdr->e_phoff + (char *)ehdr);
 216         for (j = ehdr->e_phnum; --j >= 0; ++phdr) {
 217                 if (type == byteswap32_to_host(phdr->p_type)) {
 218                         return phdr;
 219                 }
 220         }
 221         return NULL;
 222 }
 223
 224 /* Returns value if return_val==1, ptr otherwise */
 225 static void *elf_find_dynamic(int64_t const key, ElfW(Dyn) *dynp,
 226                        ElfW(Ehdr) *ehdr, int return_val)
 227 {
 228         ElfW(Phdr) *pt_text = elf_find_phdr_type(PT_LOAD, ehdr);
 229         unsigned tx_reloc = byteswap_to_host(pt_text->p_vaddr) - byteswap_to_host(pt_text->p_offset);
 230         for (; DT_NULL != byteswap_to_host(dynp->d_tag); ++dynp) {
 231                 if (key == byteswap_to_host(dynp->d_tag)) {
 232                         if (return_val == 1)
 233                                 return (void *)byteswap_to_host(dynp->d_un.d_val);
 234                         else
 235                                 return (void *)(byteswap_to_host(dynp->d_un.d_val) - tx_reloc + (char *)ehdr);
 236                 }
 237         }
 238         return NULL;
 239 }
 240
 241 static char *elf_find_rpath(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic)
 242 {
 243         ElfW(Dyn) *dyns;
 244
 245         for (dyns = dynamic; byteswap_to_host(dyns->d_tag) != DT_NULL; ++dyns) {
 246                 if (DT_RPATH == byteswap_to_host(dyns->d_tag)) {
 247                         char *strtab;
 248                         strtab = (char *)elf_find_dynamic(DT_STRTAB, dynamic, ehdr, 0);
 249                         return ((char *)strtab + byteswap_to_host(dyns->d_un.d_val));
 250                 }
 251         }
 252         return NULL;
 253 }
 254
 255 static int check_elf_header(ElfW(Ehdr) *const ehdr)
 256 {
 257         if (!ehdr || *(uint32_t*)ehdr != ELFMAG_U32
 258          /* Use __WORDSIZE, not ELFCLASSM which depends on the host */
 259          || ehdr->e_ident[EI_CLASS] != (__WORDSIZE >> 5)
 260          || ehdr->e_ident[EI_VERSION] != EV_CURRENT
 261         ) {
 262                 return 1;
 263         }
 264
 265         /* Check if the target endianness matches the host's endianness */
 266         byteswap = !(ehdr->e_ident[5] == ELFDATAM);
 267
 268         /* Be very lazy, and only byteswap the stuff we use */
 269         if (byteswap) {
 270                 ehdr->e_type = bswap_16(ehdr->e_type);
 271                 ehdr->e_phoff = byteswap_to_host(ehdr->e_phoff);
 272                 ehdr->e_shoff = byteswap_to_host(ehdr->e_shoff);
 273                 ehdr->e_phnum = bswap_16(ehdr->e_phnum);
 274                 ehdr->e_shnum = bswap_16(ehdr->e_shnum);
 275         }
 276
 277         return 0;
 278 }
 279
 280 #ifdef __LDSO_CACHE_SUPPORT__
 281 static caddr_t cache_addr = NULL;
 282 static size_t cache_size = 0;
 283
 284 static int map_cache(void)
 285 {
 286         int fd;
 287         struct stat st;
 288         header_t *header;
 289         libentry_t *libent;
 290         int i, strtabsize;
 291
 292         if (cache_addr == (caddr_t) - 1)
 293                 return -1;
 294         else if (cache_addr != NULL)
 295                 return 0;
 296
 297         if (stat(LDSO_CACHE, &st) || (fd = open(LDSO_CACHE, O_RDONLY)) < 0) {
 298                 fprintf(stderr, "ldd: can't open cache '%s'\n", LDSO_CACHE);
 299                 cache_addr = (caddr_t) - 1;     /* so we won't try again */
 300                 return -1;
 301         }
 302
 303         cache_size = st.st_size;
 304         cache_addr = mmap(0, cache_size, PROT_READ, MAP_SHARED, fd, 0);
 305         close(fd);
 306         if (cache_addr == MAP_FAILED) {
 307                 fprintf(stderr, "ldd: can't map cache '%s'\n", LDSO_CACHE);
 308                 return -1;
 309         }
 310
 311         header = (header_t *) cache_addr;
 312
 313         if (cache_size < sizeof(header_t)
 314             || memcmp(header->magic, LDSO_CACHE_MAGIC, LDSO_CACHE_MAGIC_LEN)
 315             || memcmp(header->version, LDSO_CACHE_VER, LDSO_CACHE_VER_LEN)
 316             || cache_size < (sizeof(header_t) + header->nlibs * sizeof(libentry_t))
 317             || cache_addr[cache_size - 1] != '\0')
 318         {
 319                 fprintf(stderr, "ldd: cache '%s' is corrupt\n", LDSO_CACHE);
 320                 goto fail;
 321         }
 322
 323         strtabsize = cache_size - sizeof(header_t) - header->nlibs * sizeof(libentry_t);
 324         libent = (libentry_t *) & header[1];
 325
 326         for (i = 0; i < header->nlibs; i++) {
 327                 if (libent[i].sooffset >= strtabsize || libent[i].liboffset >= strtabsize) {
 328                         fprintf(stderr, "ldd: cache '%s' is corrupt\n", LDSO_CACHE);
 329                         goto fail;
 330                 }
 331         }
 332
 333         return 0;
 334
 335 fail:
 336         munmap(cache_addr, cache_size);
 337         cache_addr = (caddr_t) - 1;
 338         return -1;
 339 }
 340
 341 static int unmap_cache(void)
 342 {
 343         if (cache_addr == NULL || cache_addr == (caddr_t) - 1)
 344                 return -1;
 345
 346 #if 1
 347         munmap(cache_addr, cache_size);
 348         cache_addr = NULL;
 349 #endif
 350
 351         return 0;
 352 }
 353 #else
 354 static __inline__ void map_cache(void)
 355 {
 356 }
 357 static __inline__ void unmap_cache(void)
 358 {
 359 }
 360 #endif
 361
 362 /* This function's behavior must exactly match that
 363  * in uClibc/ldso/ldso/dl-elf.c */
 364 static void search_for_named_library(char *name, char *result,
 365                                      const char *path_list)
 366 {
 367         int i, count = 1;
 368         char *path, *path_n;
 369         struct stat filestat;
 370
 371         /* We need a writable copy of this string */
 372         path = strdup(path_list);
 373         if (!path) {
 374                 fprintf(stderr, "%s: Out of memory!\n", __func__);
 375                 exit(EXIT_FAILURE);
 376         }
 377         /* Eliminate all double //s */
 378         path_n = path;
 379         while ((path_n = strstr(path_n, "//"))) {
 380                 i = strlen(path_n);
 381                 memmove(path_n, path_n + 1, i - 1);
 382                 *(path_n + i - 1) = '\0';
 383         }
 384
 385         /* Replace colons with zeros in path_list and count them */
 386         for (i = strlen(path); i > 0; i--) {
 387                 if (path[i] == ':') {
 388                         path[i] = 0;
 389                         count++;
 390                 }
 391         }
 392         path_n = path;
 393         for (i = 0; i < count; i++) {
 394                 strcpy(result, path_n);
 395                 strcat(result, "/");
 396                 strcat(result, name);
 397                 if (stat(result, &filestat) == 0 && filestat.st_mode & S_IRUSR) {
 398                         free(path);
 399                         return;
 400                 }
 401                 path_n += (strlen(path_n) + 1);
 402         }
 403         free(path);
 404         *result = '\0';
 405 }
 406
 407 static void locate_library_file(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic,
 408                                 int is_suid, struct library *lib)
 409 {
 410         char *buf;
 411         char *path;
 412         struct stat filestat;
 413
 414         /* If this is a fully resolved name, our job is easy */
 415         if (stat(lib->name, &filestat) == 0) {
 416                 lib->path = strdup(lib->name);
 417                 return;
 418         }
 419
 420         /* We need some elbow room here.  Make some room... */
 421         buf = malloc(1024);
 422         if (!buf) {
 423                 fprintf(stderr, "%s: Out of memory!\n", __func__);
 424                 exit(EXIT_FAILURE);
 425         }
 426
 427         /* This function must match the behavior of _dl_load_shared_library
 428          * in readelflib1.c or things won't work out as expected... */
 429
 430         /* The ABI specifies that RPATH is searched first, so do that now.  */
 431         path = elf_find_rpath(ehdr, dynamic);
 432         if (path) {
 433                 search_for_named_library(lib->name, buf, path);
 434                 if (*buf != '\0') {
 435                         lib->path = buf;
 436                         return;
 437                 }
 438         }
 439
 440         /* Next check LD_{ELF_}LIBRARY_PATH if specified and allowed.
 441          * Since this app doesn't actually run an executable I will skip
 442          * the suid check, and just use LD_{ELF_}LIBRARY_PATH if set */
 443         if (is_suid == 1)
 444                 path = NULL;
 445         else
 446                 path = getenv("LD_LIBRARY_PATH");
 447         if (path) {
 448                 search_for_named_library(lib->name, buf, path);
 449                 if (*buf != '\0') {
 450                         lib->path = buf;
 451                         return;
 452                 }
 453         }
 454 #ifdef __LDSO_CACHE_SUPPORT__
 455         if (cache_addr != NULL && cache_addr != (caddr_t) - 1) {
 456                 int i;
 457                 header_t *header = (header_t *) cache_addr;
 458                 libentry_t *libent = (libentry_t *) & header[1];
 459                 char *strs = (char *)&libent[header->nlibs];
 460
 461                 for (i = 0; i < header->nlibs; i++) {
 462                         if ((libent[i].flags == LIB_ELF ||
 463                              libent[i].flags == LIB_ELF_LIBC0 ||
 464                              libent[i].flags == LIB_ELF_LIBC5) &&
 465                             strcmp(lib->name, strs + libent[i].sooffset) == 0)
 466                         {
 467                                 lib->path = strdup(strs + libent[i].liboffset);
 468                                 return;
 469                         }
 470                 }
 471         }
 472 #endif
 473
 474         /* Next look for libraries wherever the shared library
 475          * loader was installed -- this is usually where we
 476          * should find things... */
 477         if (interp_dir) {
 478                 search_for_named_library(lib->name, buf, interp_dir);
 479                 if (*buf != '\0') {
 480                         lib->path = buf;
 481                         return;
 482                 }
 483         }
 484
 485         /* Lastly, search the standard list of paths for the library.
 486            This list must exactly match the list in uClibc/ldso/ldso/dl-elf.c */
 487         path = UCLIBC_RUNTIME_PREFIX "lib:" UCLIBC_RUNTIME_PREFIX "usr/lib"
 488 #ifndef __LDSO_CACHE_SUPPORT__
 489             ":" UCLIBC_RUNTIME_PREFIX "usr/X11R6/lib"
 490 #endif
 491             ;
 492         search_for_named_library(lib->name, buf, path);
 493         if (*buf != '\0') {
 494                 lib->path = buf;
 495         } else {
 496                 free(buf);
 497                 lib->path = not_found;
 498         }
 499 }
 500
 501 static int add_library(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic, int is_setuid, char *s)
 502 {
 503         char *tmp, *tmp1, *tmp2;
 504         struct library *cur, *newlib = lib_list;
 505
 506         if (!s || !strlen(s))
 507                 return 1;
 508
 509         tmp = s;
 510         while (*tmp) {
 511                 if (*tmp == '/')
 512                         s = tmp + 1;
 513                 tmp++;
 514         }
 515
 516         /* We add ldso elsewhere */
 517         if (interpreter_already_found && (tmp = strrchr(interp_name, '/')) != NULL) {
 518                 int len = strlen(interp_dir);
 519                 if (strcmp(s, interp_name + 1 + len) == 0)
 520                         return 1;
 521         }
 522
 523         for (cur = lib_list; cur; cur = cur->next) {
 524                 /* Check if this library is already in the list */
 525                 tmp1 = tmp2 = cur->name;
 526                 if (!cur->name)
 527                         continue;
 528                 while (*tmp1) {
 529                         if (*tmp1 == '/')
 530                                 tmp2 = tmp1 + 1;
 531                         tmp1++;
 532                 }
 533                 if (strcmp(tmp2, s) == 0) {
 534                         /*printf("find_elf_interpreter is skipping '%s' (already in list)\n", cur->name); */
 535                         return 0;
 536                 }
 537         }
 538
 539         /* Ok, this lib needs to be added to the list */
 540         newlib = malloc(sizeof(struct library));
 541         if (!newlib)
 542                 return 1;
 543         newlib->name = malloc(strlen(s) + 1);
 544         strcpy(newlib->name, s);
 545         newlib->resolved = 0;
 546         newlib->path = NULL;
 547         newlib->next = NULL;
 548
 549         /* Now try and locate where this library might be living... */
 550         locate_library_file(ehdr, dynamic, is_setuid, newlib);
 551
 552         /*printf("add_library is adding '%s' to '%s'\n", newlib->name, newlib->path); */
 553         if (!lib_list) {
 554                 lib_list = newlib;
 555         } else {
 556                 for (cur = lib_list; cur->next; cur = cur->next) ;      /* nothing */
 557                 cur->next = newlib;
 558         }
 559         return 0;
 560 }
 561
 562 static void find_needed_libraries(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic, int is_setuid)
 563 {
 564         ElfW(Dyn) *dyns;
 565
 566         for (dyns = dynamic; byteswap_to_host(dyns->d_tag) != DT_NULL; ++dyns) {
 567                 if (DT_NEEDED == byteswap_to_host(dyns->d_tag)) {
 568                         char *strtab;
 569                         strtab = (char *)elf_find_dynamic(DT_STRTAB, dynamic, ehdr, 0);
 570                         add_library(ehdr, dynamic, is_setuid, (char *)strtab + byteswap_to_host(dyns->d_un.d_val));
 571                 }
 572         }
 573 }
 574
 575 #ifdef __LDSO_LDD_SUPPORT__
 576 static struct library *find_elf_interpreter(ElfW(Ehdr) *ehdr)
 577 {
 578         ElfW(Phdr) *phdr;
 579
 580         if (interpreter_already_found == 1)
 581                 return NULL;
 582         phdr = elf_find_phdr_type(PT_INTERP, ehdr);
 583         if (phdr) {
 584                 struct library *cur, *newlib = NULL;
 585                 char *s = (char *)ehdr + byteswap_to_host(phdr->p_offset);
 586
 587                 char *tmp, *tmp1;
 588                 interp_name = strdup(s);
 589                 interp_dir = strdup(s);
 590                 tmp = strrchr(interp_dir, '/');
 591                 if (tmp)
 592                         *tmp = '\0';
 593                 else {
 594                         free(interp_dir);
 595                         interp_dir = interp_name;
 596                 }
 597                 tmp1 = tmp = s;
 598                 while (*tmp) {
 599                         if (*tmp == '/')
 600                                 tmp1 = tmp + 1;
 601                         tmp++;
 602                 }
 603                 for (cur = lib_list; cur; cur = cur->next) {
 604                         /* Check if this library is already in the list */
 605                         if (!tmp1 || !cur->name)
 606                                 return NULL;
 607                         if (strcmp(cur->name, tmp1) == 0) {
 608                                 /*printf("find_elf_interpreter is replacing '%s' (already in list)\n", cur->name); */
 609                                 newlib = cur;
 610                                 free(newlib->name);
 611                                 if (newlib->path != not_found) {
 612                                         free(newlib->path);
 613                                 }
 614                                 newlib->name = NULL;
 615                                 newlib->path = NULL;
 616                                 break;
 617                         }
 618                 }
 619                 if (newlib == NULL)
 620                         newlib = malloc(sizeof(struct library));
 621                 if (!newlib)
 622                         return NULL;
 623                 newlib->name = malloc(strlen(s) + 1);
 624                 strcpy(newlib->name, s);
 625                 newlib->path = strdup(newlib->name);
 626                 newlib->resolved = 1;
 627                 newlib->next = NULL;
 628
 629 #if 0
 630                 /*printf("find_elf_interpreter is adding '%s' to '%s'\n", newlib->name, newlib->path); */
 631                 if (!lib_list) {
 632                         lib_list = newlib;
 633                 } else {
 634                         for (cur = lib_list; cur->next; cur = cur->next) ;      /* nothing */
 635                         cur->next = newlib;
 636                 }
 637 #endif
 638                 interpreter_already_found = 1;
 639                 return newlib;
 640         }
 641         return NULL;
 642 }
 643 #endif /* __LDSO_LDD_SUPPORT__ */
 644
 645 /* map the .so, and locate interesting pieces */
 646 /*
 647 #warning "There may be two warnings here about vfork() clobbering, ignore them"
 648 */
 649 static int find_dependencies(char *filename)
 650 {
 651         int is_suid = 0;
 652         FILE *thefile;
 653         struct stat statbuf;
 654         ElfW(Ehdr) *ehdr = NULL;
 655         ElfW(Shdr) *dynsec = NULL;
 656         ElfW(Dyn) *dynamic = NULL;
 657 #ifdef __LDSO_LDD_SUPPORT__
 658         struct library *interp;
 659 #endif
 660
 661         if (filename == not_found)
 662                 return 0;
 663
 664         if (!filename) {
 665                 fprintf(stderr, "No filename specified.\n");
 666                 return -1;
 667         }
 668         if (!(thefile = fopen(filename, "r"))) {
 669                 perror(filename);
 670                 return -1;
 671         }
 672         if (fstat(fileno(thefile), &statbuf) < 0) {
 673                 perror(filename);
 674                 fclose(thefile);
 675                 return -1;
 676         }
 677
 678         if ((size_t) statbuf.st_size < sizeof(ElfW(Ehdr)))
 679                 goto foo;
 680
 681         if (!S_ISREG(statbuf.st_mode))
 682                 goto foo;
 683
 684         /* mmap the file to make reading stuff from it effortless */
 685         ehdr = mmap(0, statbuf.st_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fileno(thefile), 0);
 686         if (ehdr == MAP_FAILED) {
 687                 fclose(thefile);
 688                 fprintf(stderr, "mmap(%s) failed: %s\n", filename, strerror(errno));
 689                 return -1;
 690         }
 691
 692 foo:
 693         fclose(thefile);
 694
 695         /* Check if this looks like a legit ELF file */
 696         if (check_elf_header(ehdr)) {
 697                 fprintf(stderr, "%s: not an ELF file.\n", filename);
 698                 return -1;
 699         }
 700         /* Check if this is the right kind of ELF file */
 701         if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) {
 702                 fprintf(stderr, "%s: not a dynamic executable\n", filename);
 703                 return -1;
 704         }
 705         if (ehdr->e_type == ET_EXEC || ehdr->e_type == ET_DYN) {
 706                 if (statbuf.st_mode & S_ISUID)
 707                         is_suid = 1;
 708                 if ((statbuf.st_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP))
 709                         is_suid = 1;
 710                 /* FIXME */
 711                 if (is_suid)
 712                         fprintf(stderr, "%s: is setuid\n", filename);
 713         }
 714
 715         interpreter_already_found = 0;
 716 #ifdef __LDSO_LDD_SUPPORT__
 717         interp = find_elf_interpreter(ehdr);
 718
 719         if (interp
 720             && (ehdr->e_type == ET_EXEC || ehdr->e_type == ET_DYN)
 721             && ehdr->e_ident[EI_CLASS] == ELFCLASSM
 722             && ehdr->e_ident[EI_DATA] == ELFDATAM
 723             && ehdr->e_ident[EI_VERSION] == EV_CURRENT
 724             && MATCH_MACHINE(ehdr->e_machine))
 725         {
 726                 struct stat st;
 727                 if (stat(interp->path, &st) == 0 && S_ISREG(st.st_mode)) {
 728                         pid_t pid;
 729                         int status;
 730                         static const char *const environment[] = {
 731                                 "PATH=/usr/bin:/bin:/usr/sbin:/sbin",
 732                                 "SHELL=/bin/sh",
 733                                 "LD_TRACE_LOADED_OBJECTS=1",
 734                                 NULL
 735                         };
 736 # ifdef __LDSO_STANDALONE_SUPPORT__
 737                         char * lib_path = getenv("LD_LIBRARY_PATH");
 738
 739                         /* The 'extended' environment inclusing the LD_LIBRARY_PATH */
 740                         static char *ext_environment[ARRAY_SIZE(environment) + 1];
 741                         char **envp = (char **) environment;
 742
 743                         if (lib_path) {
 744                                 /*
 745                                  * If the LD_LIBRARY_PATH is set, it needs to include it
 746                                  * into the environment for the new process to be spawned
 747                                  */
 748                                 char ** eenvp = (char **) ext_environment;
 749
 750                                 /* Copy the N-1 environment's entries */
 751                                 while (*envp)
 752                                         *eenvp++=*envp++;
 753
 754                                 /* Make room for LD_LIBRARY_PATH */
 755                                 *eenvp = (char *) malloc(sizeof("LD_LIBRARY_PATH=")
 756                                                                           + strlen(lib_path));
 757                                 strcpy(*eenvp, "LD_LIBRARY_PATH=");
 758                                 strcat(*eenvp, lib_path);
 759                                 lib_path = *eenvp;
 760                                 /* ext_environment[size] is already NULL */
 761
 762                                 /* Use the extended environment */
 763                                 envp = ext_environment;
 764                         }
 765                         if ((pid = vfork()) == 0) {
 766                                 /*
 767                                  * Force to use the standard dynamic linker in stand-alone mode.
 768                                  * It will fails at runtime if support is not actually available
 769                                  */
 770                                 execle(TRUSTED_LDSO, TRUSTED_LDSO, filename, NULL, envp);
 771                                 _exit(0xdead);
 772                         }
 773 # else
 774                         if ((pid = vfork()) == 0) {
 775                                 /* Cool, it looks like we should be able to actually
 776                                  * run this puppy.  Do so now... */
 777                                 execle(filename, filename, NULL, environment);
 778                                 _exit(0xdead);
 779                         }
 780 # endif
 781                         /* Wait till it returns */
 782                         waitpid(pid, &status, 0);
 783
 784 # ifdef __LDSO_STANDALONE_SUPPORT__
 785                         /* Do not leak */
 786                         free(lib_path);
 787 # endif
 788
 789                         if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
 790                                 return 1;
 791                         }
 792
 793                         /* If the exec failed, we fall through to trying to find
 794                          * all the needed libraries ourselves by rummaging about
 795                          * in the ELF headers... */
 796                 }
 797         }
 798 #endif
 799
 800         dynsec = elf_find_section_type(SHT_DYNAMIC, ehdr);
 801         if (dynsec) {
 802                 dynamic = (ElfW(Dyn) *) (byteswap_to_host(dynsec->sh_offset) + (char *)ehdr);
 803                 find_needed_libraries(ehdr, dynamic, is_suid);
 804         }
 805
 806         return 0;
 807 }
 808
 809 int main(int argc, char **argv)
 810 {
 811         int multi = 0;
 812         int got_em_all = 1;
 813         char *filename = NULL;
 814         struct library *cur;
 815
 816         if (argc < 2) {
 817                 fprintf(stderr, "ldd: missing file arguments\n"
 818                                 "Try `ldd --help' for more information.\n");
 819                 exit(EXIT_FAILURE);
 820         }
 821         if (argc > 2)
 822                 multi++;
 823
 824         while (--argc > 0) {
 825                 ++argv;
 826
 827                 if (strcmp(*argv, "--") == 0) {
 828                         /* Ignore "--" */
 829                         continue;
 830                 }
 831
 832                 if (strcmp(*argv, "--help") == 0 || strcmp(*argv, "-h") == 0) {
 833                         fprintf(stderr, "Usage: ldd [OPTION]... FILE...\n"
 834                                         "\t--help\t\tprint this help and exit\n");
 835                         exit(EXIT_SUCCESS);
 836                 }
 837
 838                 filename = *argv;
 839                 if (!filename) {
 840                         fprintf(stderr, "No filename specified.\n");
 841                         exit(EXIT_FAILURE);
 842                 }
 843
 844                 if (multi) {
 845                         printf("%s:\n", *argv);
 846                 }
 847
 848                 map_cache();
 849
 850                 if (find_dependencies(filename) != 0)
 851                         continue;
 852
 853                 while (got_em_all) {
 854                         got_em_all = 0;
 855                         /* Keep walking the list till everybody is resolved */
 856                         for (cur = lib_list; cur; cur = cur->next) {
 857                                 if (cur->resolved == 0 && cur->path) {
 858                                         got_em_all = 1;
 859                                         printf("checking sub-depends for '%s'\n", cur->path);
 860                                         find_dependencies(cur->path);
 861                                         cur->resolved = 1;
 862                                 }
 863                         }
 864                 }
 865
 866                 unmap_cache();
 867
 868                 /* Print the list */
 869                 got_em_all = 0;
 870                 for (cur = lib_list; cur; cur = cur->next) {
 871                         got_em_all = 1;
 872                         printf("\t%s => %s (0x00000000)\n", cur->name, cur->path);
 873                 }
 874                 if (interp_name && interpreter_already_found == 1)
 875                         printf("\t%s => %s (0x00000000)\n", interp_name, interp_name);
 876                 else
 877                         printf("\tnot a dynamic executable\n");
 878
 879                 for (cur = lib_list; cur; cur = cur->next) {
 880                         free(cur->name);
 881                         cur->name = NULL;
 882                         if (cur->path && cur->path != not_found) {
 883                                 free(cur->path);
 884                                 cur->path = NULL;
 885                         }
 886                 }
 887                 lib_list = NULL;
 888         }
 889
 890         return 0;
 891 }