1 /* vi: set sw=4 ts=4: */
3 * A small little ldd implementation for uClibc
5 * Copyright (C) 2000-2006 Erik Andersen <andersen@uclibc.org>
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
13 * Licensed under GPLv2 or later
18 #if defined(__alpha__)
19 #define MATCH_MACHINE(x) (x == EM_ALPHA)
20 #define ELFCLASSM ELFCLASS64
23 #if defined(__arm__) || defined(__thumb__)
24 #define MATCH_MACHINE(x) (x == EM_ARM)
25 #define ELFCLASSM ELFCLASS32
28 #if defined(__avr32__)
29 #define MATCH_MACHINE(x) (x == EM_AVR32)
30 #define ELFCLASSM ELFCLASS32
34 #define MATCH_MACHINE(x) (x == EM_S390)
35 #define ELFCLASSM ELFCLASS32
39 #define MATCH_MACHINE(x) (x == EM_PARISC)
41 #define ELFCLASSM ELFCLASS64
43 #define ELFCLASSM ELFCLASS32
49 #define MATCH_MACHINE(x) (x == EM_386)
51 #define MATCH_MACHINE(x) (x == EM_386 || x == EM_486)
53 #define ELFCLASSM ELFCLASS32
57 #define MATCH_MACHINE(x) (x == EM_IA_64)
58 #define ELFCLASSM ELFCLASS64
61 #if defined(__mc68000__)
62 #define MATCH_MACHINE(x) (x == EM_68K)
63 #define ELFCLASSM ELFCLASS32
67 #define MATCH_MACHINE(x) (x == EM_MIPS || x == EM_MIPS_RS3_LE)
68 #define ELFCLASSM ELFCLASS32
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
80 #define MATCH_MACHINE(x) (x == EM_SH)
81 #define ELFCLASSM ELFCLASS32
84 #if defined(__v850e__)
85 #define MATCH_MACHINE(x) ((x) == EM_V850 || (x) == EM_CYGNUS_V850)
86 #define ELFCLASSM ELFCLASS32
89 #if defined(__sparc__)
90 #define MATCH_MACHINE(x) ((x) == EM_SPARC || (x) == EM_SPARC32PLUS)
91 #define ELFCLASSM ELFCLASS32
95 #define MATCH_MACHINE(x) (x == EM_CRIS)
96 #define ELFCLASSM ELFCLASS32
99 #if defined(__x86_64__)
100 #define MATCH_MACHINE(x) (x == EM_X86_64)
101 #define ELFCLASSM ELFCLASS64
104 #if defined(__microblaze__)
105 #define MATCH_MACHINE(x) (x == EM_MICROBLAZE_OLD)
106 #define ELFCLASSM ELFCLASS32
109 #ifndef MATCH_MACHINE
111 # include <asm/elf.h>
114 # define MATCH_MACHINE(x) (x == ELF_ARCH)
117 # define ELFCLASSM ELF_CLASS
120 #ifndef MATCH_MACHINE
121 # warning "You really should add a MATCH_MACHINE() macro for your architecture"
124 #if UCLIBC_ENDIAN_HOST == UCLIBC_ENDIAN_LITTLE
125 #define ELFDATAM ELFDATA2LSB
126 #elif UCLIBC_ENDIAN_HOST == UCLIBC_ENDIAN_BIG
127 #define ELFDATAM ELFDATA2MSB
130 #define TRUSTED_LDSO UCLIBC_RUNTIME_PREFIX "lib/" UCLIBC_LDSO
136 struct library *next;
138 static struct library *lib_list = NULL;
139 static char not_found[] = "not found";
140 static char *interp_name = NULL;
141 static char *interp_dir = NULL;
143 static int interpreter_already_found = 0;
145 static __inline__ uint32_t byteswap32_to_host(uint32_t value)
148 return (bswap_32(value));
153 static __inline__ uint64_t byteswap64_to_host(uint64_t value)
156 return (bswap_64(value));
162 #if ELFCLASSM == ELFCLASS32
163 # define byteswap_to_host(x) byteswap32_to_host(x)
165 # define byteswap_to_host(x) byteswap64_to_host(x)
168 static ElfW(Shdr) *elf_find_section_type(uint32_t key, ElfW(Ehdr) *ehdr)
172 shdr = (ElfW(Shdr) *) (ehdr->e_shoff + (char *)ehdr);
173 for (j = ehdr->e_shnum; --j >= 0; ++shdr) {
174 if (key == byteswap32_to_host(shdr->sh_type)) {
181 static ElfW(Phdr) *elf_find_phdr_type(uint32_t type, ElfW(Ehdr) *ehdr)
184 ElfW(Phdr) *phdr = (ElfW(Phdr) *) (ehdr->e_phoff + (char *)ehdr);
185 for (j = ehdr->e_phnum; --j >= 0; ++phdr) {
186 if (type == byteswap32_to_host(phdr->p_type)) {
193 /* Returns value if return_val==1, ptr otherwise */
194 static void *elf_find_dynamic(int64_t const key, ElfW(Dyn) *dynp,
195 ElfW(Ehdr) *ehdr, int return_val)
197 ElfW(Phdr) *pt_text = elf_find_phdr_type(PT_LOAD, ehdr);
198 unsigned tx_reloc = byteswap_to_host(pt_text->p_vaddr) - byteswap_to_host(pt_text->p_offset);
199 for (; DT_NULL != byteswap_to_host(dynp->d_tag); ++dynp) {
200 if (key == byteswap_to_host(dynp->d_tag)) {
202 return (void *)byteswap_to_host(dynp->d_un.d_val);
204 return (void *)(byteswap_to_host(dynp->d_un.d_val) - tx_reloc + (char *)ehdr);
210 static char *elf_find_rpath(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic)
214 for (dyns = dynamic; byteswap_to_host(dyns->d_tag) != DT_NULL; ++dyns) {
215 if (DT_RPATH == byteswap_to_host(dyns->d_tag)) {
217 strtab = (char *)elf_find_dynamic(DT_STRTAB, dynamic, ehdr, 0);
218 return ((char *)strtab + byteswap_to_host(dyns->d_un.d_val));
224 static int check_elf_header(ElfW(Ehdr) *const ehdr)
226 if (!ehdr || *(uint32_t*)ehdr != ELFMAG_U32
227 || ehdr->e_ident[EI_CLASS] != ELFCLASSM
228 || ehdr->e_ident[EI_VERSION] != EV_CURRENT
233 /* Check if the target endianness matches the host's endianness */
235 if (UCLIBC_ENDIAN_HOST == UCLIBC_ENDIAN_LITTLE) {
236 if (ehdr->e_ident[5] == ELFDATA2MSB)
238 } else if (UCLIBC_ENDIAN_HOST == UCLIBC_ENDIAN_BIG) {
239 if (ehdr->e_ident[5] == ELFDATA2LSB)
243 /* Be very lazy, and only byteswap the stuff we use */
245 ehdr->e_type = bswap_16(ehdr->e_type);
246 ehdr->e_phoff = byteswap_to_host(ehdr->e_phoff);
247 ehdr->e_shoff = byteswap_to_host(ehdr->e_shoff);
248 ehdr->e_phnum = bswap_16(ehdr->e_phnum);
249 ehdr->e_shnum = bswap_16(ehdr->e_shnum);
255 #ifdef __LDSO_CACHE_SUPPORT__
256 static caddr_t cache_addr = NULL;
257 static size_t cache_size = 0;
259 static int map_cache(void)
267 if (cache_addr == (caddr_t) - 1)
269 else if (cache_addr != NULL)
272 if (stat(LDSO_CACHE, &st) || (fd = open(LDSO_CACHE, O_RDONLY)) < 0) {
273 fprintf(stderr, "ldd: can't open cache '%s'\n", LDSO_CACHE);
274 cache_addr = (caddr_t) - 1; /* so we won't try again */
278 cache_size = st.st_size;
279 cache_addr = mmap(0, cache_size, PROT_READ, MAP_SHARED, fd, 0);
281 if (cache_addr == MAP_FAILED) {
282 fprintf(stderr, "ldd: can't map cache '%s'\n", LDSO_CACHE);
286 header = (header_t *) cache_addr;
288 if (cache_size < sizeof(header_t)
289 || memcmp(header->magic, LDSO_CACHE_MAGIC, LDSO_CACHE_MAGIC_LEN)
290 || memcmp(header->version, LDSO_CACHE_VER, LDSO_CACHE_VER_LEN)
291 || cache_size < (sizeof(header_t) + header->nlibs * sizeof(libentry_t))
292 || cache_addr[cache_size - 1] != '\0')
294 fprintf(stderr, "ldd: cache '%s' is corrupt\n", LDSO_CACHE);
298 strtabsize = cache_size - sizeof(header_t) - header->nlibs * sizeof(libentry_t);
299 libent = (libentry_t *) & header[1];
301 for (i = 0; i < header->nlibs; i++) {
302 if (libent[i].sooffset >= strtabsize || libent[i].liboffset >= strtabsize) {
303 fprintf(stderr, "ldd: cache '%s' is corrupt\n", LDSO_CACHE);
311 munmap(cache_addr, cache_size);
312 cache_addr = (caddr_t) - 1;
316 static int unmap_cache(void)
318 if (cache_addr == NULL || cache_addr == (caddr_t) - 1)
322 munmap(cache_addr, cache_size);
329 static __inline__ void map_cache(void)
332 static __inline__ void unmap_cache(void)
337 /* This function's behavior must exactly match that
338 * in uClibc/ldso/ldso/dl-elf.c */
339 static void search_for_named_library(char *name, char *result,
340 const char *path_list)
344 struct stat filestat;
346 /* We need a writable copy of this string */
347 path = strdup(path_list);
349 fprintf(stderr, "%s: Out of memory!\n", __func__);
352 /* Eliminate all double //s */
354 while ((path_n = strstr(path_n, "//"))) {
356 memmove(path_n, path_n + 1, i - 1);
357 *(path_n + i - 1) = '\0';
360 /* Replace colons with zeros in path_list and count them */
361 for (i = strlen(path); i > 0; i--) {
362 if (path[i] == ':') {
368 for (i = 0; i < count; i++) {
369 strcpy(result, path_n);
371 strcat(result, name);
372 if (stat(result, &filestat) == 0 && filestat.st_mode & S_IRUSR) {
376 path_n += (strlen(path_n) + 1);
382 static void locate_library_file(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic,
383 int is_suid, struct library *lib)
387 struct stat filestat;
389 /* If this is a fully resolved name, our job is easy */
390 if (stat(lib->name, &filestat) == 0) {
391 lib->path = strdup(lib->name);
395 /* We need some elbow room here. Make some room... */
398 fprintf(stderr, "%s: Out of memory!\n", __func__);
402 /* This function must match the behavior of _dl_load_shared_library
403 * in readelflib1.c or things won't work out as expected... */
405 /* The ABI specifies that RPATH is searched first, so do that now. */
406 path = elf_find_rpath(ehdr, dynamic);
408 search_for_named_library(lib->name, buf, path);
415 /* Next check LD_{ELF_}LIBRARY_PATH if specified and allowed.
416 * Since this app doesn't actually run an executable I will skip
417 * the suid check, and just use LD_{ELF_}LIBRARY_PATH if set */
421 path = getenv("LD_LIBRARY_PATH");
423 search_for_named_library(lib->name, buf, path);
429 #ifdef __LDSO_CACHE_SUPPORT__
430 if (cache_addr != NULL && cache_addr != (caddr_t) - 1) {
432 header_t *header = (header_t *) cache_addr;
433 libentry_t *libent = (libentry_t *) & header[1];
434 char *strs = (char *)&libent[header->nlibs];
436 for (i = 0; i < header->nlibs; i++) {
437 if ((libent[i].flags == LIB_ELF ||
438 libent[i].flags == LIB_ELF_LIBC0 ||
439 libent[i].flags == LIB_ELF_LIBC5) &&
440 strcmp(lib->name, strs + libent[i].sooffset) == 0)
442 lib->path = strdup(strs + libent[i].liboffset);
449 /* Next look for libraries wherever the shared library
450 * loader was installed -- this is usually where we
451 * should find things... */
453 search_for_named_library(lib->name, buf, interp_dir);
460 /* Lastly, search the standard list of paths for the library.
461 This list must exactly match the list in uClibc/ldso/ldso/dl-elf.c */
462 path = UCLIBC_RUNTIME_PREFIX "lib:" UCLIBC_RUNTIME_PREFIX "usr/lib"
463 #ifndef __LDSO_CACHE_SUPPORT__
464 ":" UCLIBC_RUNTIME_PREFIX "usr/X11R6/lib"
467 search_for_named_library(lib->name, buf, path);
472 lib->path = not_found;
476 static int add_library(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic, int is_setuid, char *s)
478 char *tmp, *tmp1, *tmp2;
479 struct library *cur, *newlib = lib_list;
481 if (!s || !strlen(s))
491 /* We add ldso elsewhere */
492 if (interpreter_already_found && (tmp = strrchr(interp_name, '/')) != NULL) {
493 int len = strlen(interp_dir);
494 if (strcmp(s, interp_name + 1 + len) == 0)
498 for (cur = lib_list; cur; cur = cur->next) {
499 /* Check if this library is already in the list */
500 tmp1 = tmp2 = cur->name;
506 if (strcmp(tmp2, s) == 0) {
507 /*printf("find_elf_interpreter is skipping '%s' (already in list)\n", cur->name); */
512 /* Ok, this lib needs to be added to the list */
513 newlib = malloc(sizeof(struct library));
516 newlib->name = malloc(strlen(s) + 1);
517 strcpy(newlib->name, s);
518 newlib->resolved = 0;
522 /* Now try and locate where this library might be living... */
523 locate_library_file(ehdr, dynamic, is_setuid, newlib);
525 /*printf("add_library is adding '%s' to '%s'\n", newlib->name, newlib->path); */
529 for (cur = lib_list; cur->next; cur = cur->next) ; /* nothing */
535 static void find_needed_libraries(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic, int is_setuid)
539 for (dyns = dynamic; byteswap_to_host(dyns->d_tag) != DT_NULL; ++dyns) {
540 if (DT_NEEDED == byteswap_to_host(dyns->d_tag)) {
542 strtab = (char *)elf_find_dynamic(DT_STRTAB, dynamic, ehdr, 0);
543 add_library(ehdr, dynamic, is_setuid, (char *)strtab + byteswap_to_host(dyns->d_un.d_val));
548 static struct library *find_elf_interpreter(ElfW(Ehdr) *ehdr)
552 if (interpreter_already_found == 1)
554 phdr = elf_find_phdr_type(PT_INTERP, ehdr);
556 struct library *cur, *newlib = NULL;
557 char *s = (char *)ehdr + byteswap_to_host(phdr->p_offset);
560 interp_name = strdup(s);
561 interp_dir = strdup(s);
562 tmp = strrchr(interp_dir, '/');
567 interp_dir = interp_name;
575 for (cur = lib_list; cur; cur = cur->next) {
576 /* Check if this library is already in the list */
577 if (strcmp(cur->name, tmp1) == 0) {
578 /*printf("find_elf_interpreter is replacing '%s' (already in list)\n", cur->name); */
581 if (newlib->path != not_found) {
590 newlib = malloc(sizeof(struct library));
593 newlib->name = malloc(strlen(s) + 1);
594 strcpy(newlib->name, s);
595 newlib->path = strdup(newlib->name);
596 newlib->resolved = 1;
600 /*printf("find_elf_interpreter is adding '%s' to '%s'\n", newlib->name, newlib->path); */
604 for (cur = lib_list; cur->next; cur = cur->next) ; /* nothing */
608 interpreter_already_found = 1;
614 /* map the .so, and locate interesting pieces */
616 #warning "There may be two warnings here about vfork() clobbering, ignore them"
618 static int find_dependencies(char *filename)
622 struct library *interp;
624 ElfW(Ehdr) *ehdr = NULL;
625 ElfW(Shdr) *dynsec = NULL;
626 ElfW(Dyn) *dynamic = NULL;
628 if (filename == not_found)
632 fprintf(stderr, "No filename specified.\n");
635 if (!(thefile = fopen(filename, "r"))) {
639 if (fstat(fileno(thefile), &statbuf) < 0) {
645 if ((size_t) statbuf.st_size < sizeof(ElfW(Ehdr)))
648 if (!S_ISREG(statbuf.st_mode))
651 /* mmap the file to make reading stuff from it effortless */
652 ehdr = mmap(0, statbuf.st_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fileno(thefile), 0);
653 if (ehdr == MAP_FAILED) {
655 fprintf(stderr, "mmap(%s) failed: %s\n", filename, strerror(errno));
662 /* Check if this looks like a legit ELF file */
663 if (check_elf_header(ehdr)) {
664 fprintf(stderr, "%s: not an ELF file.\n", filename);
667 /* Check if this is the right kind of ELF file */
668 if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) {
669 fprintf(stderr, "%s: not a dynamic executable\n", filename);
672 if (ehdr->e_type == ET_EXEC || ehdr->e_type == ET_DYN) {
673 if (statbuf.st_mode & S_ISUID)
675 if ((statbuf.st_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP))
679 fprintf(stderr, "%s: is setuid\n", filename);
682 interpreter_already_found = 0;
683 interp = find_elf_interpreter(ehdr);
685 #ifdef __LDSO_LDD_SUPPORT__
687 && (ehdr->e_type == ET_EXEC || ehdr->e_type == ET_DYN)
688 && ehdr->e_ident[EI_CLASS] == ELFCLASSM
689 && ehdr->e_ident[EI_DATA] == ELFDATAM
690 && ehdr->e_ident[EI_VERSION] == EV_CURRENT
691 && MATCH_MACHINE(ehdr->e_machine))
694 if (stat(interp->path, &st) == 0 && S_ISREG(st.st_mode)) {
697 static const char *const environment[] = {
698 "PATH=/usr/bin:/bin:/usr/sbin:/sbin",
700 "LD_TRACE_LOADED_OBJECTS=1",
703 #ifdef __LDSO_STANDALONE_SUPPORT__
704 char * lib_path = getenv("LD_LIBRARY_PATH");
706 /* The 'extended' environment inclusing the LD_LIBRARY_PATH */
707 static char *ext_environment[ARRAY_SIZE(environment) + 1];
708 char **envp = (char **) environment;
712 * If the LD_LIBRARY_PATH is set, it needs to include it
713 * into the environment for the new process to be spawned
715 char ** eenvp = (char **) ext_environment;
717 /* Copy the N-1 environment's entries */
721 /* Make room for LD_LIBRARY_PATH */
722 *eenvp = (char *) malloc(sizeof("LD_LIBRARY_PATH=")
724 strcpy(*eenvp, "LD_LIBRARY_PATH=");
725 strcat(*eenvp, lib_path);
727 /* ext_environment[size] is already NULL */
729 /* Use the extended environment */
730 envp = ext_environment;
732 if ((pid = vfork()) == 0) {
734 * Force to use the standard dynamic linker in stand-alone mode.
735 * It will fails at runtime if support is not actually available
737 execle(TRUSTED_LDSO, TRUSTED_LDSO, filename, NULL, envp);
741 if ((pid = vfork()) == 0) {
742 /* Cool, it looks like we should be able to actually
743 * run this puppy. Do so now... */
744 execle(filename, filename, NULL, environment);
748 /* Wait till it returns */
749 waitpid(pid, &status, 0);
751 #ifdef __LDSO_STANDALONE_SUPPORT__
756 if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
760 /* If the exec failed, we fall through to trying to find
761 * all the needed libraries ourselves by rummaging about
762 * in the ELF headers... */
767 dynsec = elf_find_section_type(SHT_DYNAMIC, ehdr);
769 dynamic = (ElfW(Dyn) *) (byteswap_to_host(dynsec->sh_offset) + (char *)ehdr);
770 find_needed_libraries(ehdr, dynamic, is_suid);
776 int main(int argc, char **argv)
780 char *filename = NULL;
784 fprintf(stderr, "ldd: missing file arguments\n"
785 "Try `ldd --help' for more information.\n");
794 if (strcmp(*argv, "--") == 0) {
799 if (strcmp(*argv, "--help") == 0 || strcmp(*argv, "-h") == 0) {
800 fprintf(stderr, "Usage: ldd [OPTION]... FILE...\n"
801 "\t--help\t\tprint this help and exit\n");
807 fprintf(stderr, "No filename specified.\n");
812 printf("%s:\n", *argv);
817 if (find_dependencies(filename) != 0)
822 /* Keep walking the list till everybody is resolved */
823 for (cur = lib_list; cur; cur = cur->next) {
824 if (cur->resolved == 0 && cur->path) {
826 printf("checking sub-depends for '%s'\n", cur->path);
827 find_dependencies(cur->path);
837 for (cur = lib_list; cur; cur = cur->next) {
839 printf("\t%s => %s (0x00000000)\n", cur->name, cur->path);
841 if (interp_name && interpreter_already_found == 1)
842 printf("\t%s => %s (0x00000000)\n", interp_name, interp_name);
844 printf("\tnot a dynamic executable\n");
846 for (cur = lib_list; cur; cur = cur->next) {
849 if (cur->path && cur->path != not_found) {