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 ARRAY_SIZE(v) (sizeof(v) / sizeof(*v))
131 #define TRUSTED_LDSO UCLIBC_RUNTIME_PREFIX "lib/" UCLIBC_LDSO
137 struct library *next;
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;
144 static int interpreter_already_found = 0;
146 static __inline__ uint32_t byteswap32_to_host(uint32_t value)
149 return (bswap_32(value));
154 static __inline__ uint64_t byteswap64_to_host(uint64_t value)
157 return (bswap_64(value));
163 #if ELFCLASSM == ELFCLASS32
164 # define byteswap_to_host(x) byteswap32_to_host(x)
166 # define byteswap_to_host(x) byteswap64_to_host(x)
169 static ElfW(Shdr) *elf_find_section_type(uint32_t key, ElfW(Ehdr) *ehdr)
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)) {
182 static ElfW(Phdr) *elf_find_phdr_type(uint32_t type, ElfW(Ehdr) *ehdr)
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)) {
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)
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)) {
203 return (void *)byteswap_to_host(dynp->d_un.d_val);
205 return (void *)(byteswap_to_host(dynp->d_un.d_val) - tx_reloc + (char *)ehdr);
211 static char *elf_find_rpath(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic)
215 for (dyns = dynamic; byteswap_to_host(dyns->d_tag) != DT_NULL; ++dyns) {
216 if (DT_RPATH == byteswap_to_host(dyns->d_tag)) {
218 strtab = (char *)elf_find_dynamic(DT_STRTAB, dynamic, ehdr, 0);
219 return ((char *)strtab + byteswap_to_host(dyns->d_un.d_val));
225 static int check_elf_header(ElfW(Ehdr) *const ehdr)
227 if (!ehdr || *(uint32_t*)ehdr != ELFMAG_U32
228 || ehdr->e_ident[EI_CLASS] != ELFCLASSM
229 || ehdr->e_ident[EI_VERSION] != EV_CURRENT
234 /* Check if the target endianness matches the host's endianness */
236 if (UCLIBC_ENDIAN_HOST == UCLIBC_ENDIAN_LITTLE) {
237 if (ehdr->e_ident[5] == ELFDATA2MSB)
239 } else if (UCLIBC_ENDIAN_HOST == UCLIBC_ENDIAN_BIG) {
240 if (ehdr->e_ident[5] == ELFDATA2LSB)
244 /* Be very lazy, and only byteswap the stuff we use */
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);
256 #ifdef __LDSO_CACHE_SUPPORT__
257 static caddr_t cache_addr = NULL;
258 static size_t cache_size = 0;
260 static int map_cache(void)
268 if (cache_addr == (caddr_t) - 1)
270 else if (cache_addr != NULL)
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 */
279 cache_size = st.st_size;
280 cache_addr = mmap(0, cache_size, PROT_READ, MAP_SHARED, fd, 0);
282 if (cache_addr == MAP_FAILED) {
283 fprintf(stderr, "ldd: can't map cache '%s'\n", LDSO_CACHE);
287 header = (header_t *) cache_addr;
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')
295 fprintf(stderr, "ldd: cache '%s' is corrupt\n", LDSO_CACHE);
299 strtabsize = cache_size - sizeof(header_t) - header->nlibs * sizeof(libentry_t);
300 libent = (libentry_t *) & header[1];
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);
312 munmap(cache_addr, cache_size);
313 cache_addr = (caddr_t) - 1;
317 static int unmap_cache(void)
319 if (cache_addr == NULL || cache_addr == (caddr_t) - 1)
323 munmap(cache_addr, cache_size);
330 static __inline__ void map_cache(void)
333 static __inline__ void unmap_cache(void)
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)
345 struct stat filestat;
347 /* We need a writable copy of this string */
348 path = strdup(path_list);
350 fprintf(stderr, "%s: Out of memory!\n", __func__);
353 /* Eliminate all double //s */
355 while ((path_n = strstr(path_n, "//"))) {
357 memmove(path_n, path_n + 1, i - 1);
358 *(path_n + i - 1) = '\0';
361 /* Replace colons with zeros in path_list and count them */
362 for (i = strlen(path); i > 0; i--) {
363 if (path[i] == ':') {
369 for (i = 0; i < count; i++) {
370 strcpy(result, path_n);
372 strcat(result, name);
373 if (stat(result, &filestat) == 0 && filestat.st_mode & S_IRUSR) {
377 path_n += (strlen(path_n) + 1);
383 static void locate_library_file(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic,
384 int is_suid, struct library *lib)
388 struct stat filestat;
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);
396 /* We need some elbow room here. Make some room... */
399 fprintf(stderr, "%s: Out of memory!\n", __func__);
403 /* This function must match the behavior of _dl_load_shared_library
404 * in readelflib1.c or things won't work out as expected... */
406 /* The ABI specifies that RPATH is searched first, so do that now. */
407 path = elf_find_rpath(ehdr, dynamic);
409 search_for_named_library(lib->name, buf, path);
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 */
422 path = getenv("LD_LIBRARY_PATH");
424 search_for_named_library(lib->name, buf, path);
430 #ifdef __LDSO_CACHE_SUPPORT__
431 if (cache_addr != NULL && cache_addr != (caddr_t) - 1) {
433 header_t *header = (header_t *) cache_addr;
434 libentry_t *libent = (libentry_t *) & header[1];
435 char *strs = (char *)&libent[header->nlibs];
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)
443 lib->path = strdup(strs + libent[i].liboffset);
450 /* Next look for libraries wherever the shared library
451 * loader was installed -- this is usually where we
452 * should find things... */
454 search_for_named_library(lib->name, buf, interp_dir);
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"
468 search_for_named_library(lib->name, buf, path);
473 lib->path = not_found;
477 static int add_library(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic, int is_setuid, char *s)
479 char *tmp, *tmp1, *tmp2;
480 struct library *cur, *newlib = lib_list;
482 if (!s || !strlen(s))
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)
499 for (cur = lib_list; cur; cur = cur->next) {
500 /* Check if this library is already in the list */
501 tmp1 = tmp2 = cur->name;
507 if (strcmp(tmp2, s) == 0) {
508 /*printf("find_elf_interpreter is skipping '%s' (already in list)\n", cur->name); */
513 /* Ok, this lib needs to be added to the list */
514 newlib = malloc(sizeof(struct library));
517 newlib->name = malloc(strlen(s) + 1);
518 strcpy(newlib->name, s);
519 newlib->resolved = 0;
523 /* Now try and locate where this library might be living... */
524 locate_library_file(ehdr, dynamic, is_setuid, newlib);
526 /*printf("add_library is adding '%s' to '%s'\n", newlib->name, newlib->path); */
530 for (cur = lib_list; cur->next; cur = cur->next) ; /* nothing */
536 static void find_needed_libraries(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic, int is_setuid)
540 for (dyns = dynamic; byteswap_to_host(dyns->d_tag) != DT_NULL; ++dyns) {
541 if (DT_NEEDED == byteswap_to_host(dyns->d_tag)) {
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));
549 static struct library *find_elf_interpreter(ElfW(Ehdr) *ehdr)
553 if (interpreter_already_found == 1)
555 phdr = elf_find_phdr_type(PT_INTERP, ehdr);
557 struct library *cur, *newlib = NULL;
558 char *s = (char *)ehdr + byteswap_to_host(phdr->p_offset);
561 interp_name = strdup(s);
562 interp_dir = strdup(s);
563 tmp = strrchr(interp_dir, '/');
568 interp_dir = interp_name;
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); */
582 if (newlib->path != not_found) {
591 newlib = malloc(sizeof(struct library));
594 newlib->name = malloc(strlen(s) + 1);
595 strcpy(newlib->name, s);
596 newlib->path = strdup(newlib->name);
597 newlib->resolved = 1;
601 /*printf("find_elf_interpreter is adding '%s' to '%s'\n", newlib->name, newlib->path); */
605 for (cur = lib_list; cur->next; cur = cur->next) ; /* nothing */
609 interpreter_already_found = 1;
615 /* map the .so, and locate interesting pieces */
617 #warning "There may be two warnings here about vfork() clobbering, ignore them"
619 static int find_dependencies(char *filename)
623 struct library *interp;
625 ElfW(Ehdr) *ehdr = NULL;
626 ElfW(Shdr) *dynsec = NULL;
627 ElfW(Dyn) *dynamic = NULL;
629 if (filename == not_found)
633 fprintf(stderr, "No filename specified.\n");
636 if (!(thefile = fopen(filename, "r"))) {
640 if (fstat(fileno(thefile), &statbuf) < 0) {
646 if ((size_t) statbuf.st_size < sizeof(ElfW(Ehdr)))
649 if (!S_ISREG(statbuf.st_mode))
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) {
656 fprintf(stderr, "mmap(%s) failed: %s\n", filename, strerror(errno));
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);
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);
673 if (ehdr->e_type == ET_EXEC || ehdr->e_type == ET_DYN) {
674 if (statbuf.st_mode & S_ISUID)
676 if ((statbuf.st_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP))
680 fprintf(stderr, "%s: is setuid\n", filename);
683 interpreter_already_found = 0;
684 interp = find_elf_interpreter(ehdr);
686 #ifdef __LDSO_LDD_SUPPORT__
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))
695 if (stat(interp->path, &st) == 0 && S_ISREG(st.st_mode)) {
698 static const char *const environment[] = {
699 "PATH=/usr/bin:/bin:/usr/sbin:/sbin",
701 "LD_TRACE_LOADED_OBJECTS=1",
704 char * lib_path = getenv("LD_LIBRARY_PATH");
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;
713 * If the LD_LIBRARY_PATH is set, it needs to include it
714 * into the environment for the new process to be spawned
716 char ** eenvp = (char **) ext_environment;
718 /* Copy the N-1 environment's entries */
722 /* Make room for LD_LIBRARY_PATH */
723 *eenvp = (char *) malloc(sizeof("LD_LIBRARY_PATH=")
725 strcpy(*eenvp, "LD_LIBRARY_PATH=");
726 strcat(*eenvp, lib_path);
728 /* ext_environment[size] is already NULL */
730 /* Use the extended environment */
731 envp = ext_environment;
733 if ((pid = vfork()) == 0) {
735 * Force to use the standard dynamic linker in stand-alone mode.
736 * It will fails at runtime if support is not actually available
738 execle(TRUSTED_LDSO, TRUSTED_LDSO, filename, NULL, envp);
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);
749 /* Wait till it returns */
750 waitpid(pid, &status, 0);
752 #ifdef __LDSO_STANDALONE_SUPPORT__
757 if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
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... */
768 dynsec = elf_find_section_type(SHT_DYNAMIC, ehdr);
770 dynamic = (ElfW(Dyn) *) (byteswap_to_host(dynsec->sh_offset) + (char *)ehdr);
771 find_needed_libraries(ehdr, dynamic, is_suid);
777 int main(int argc, char **argv)
781 char *filename = NULL;
785 fprintf(stderr, "ldd: missing file arguments\n"
786 "Try `ldd --help' for more information.\n");
795 if (strcmp(*argv, "--") == 0) {
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");
808 fprintf(stderr, "No filename specified.\n");
813 printf("%s:\n", *argv);
818 if (find_dependencies(filename) != 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) {
827 printf("checking sub-depends for '%s'\n", cur->path);
828 find_dependencies(cur->path);
838 for (cur = lib_list; cur; cur = cur->next) {
840 printf("\t%s => %s (0x00000000)\n", cur->name, cur->path);
842 if (interp_name && interpreter_already_found == 1)
843 printf("\t%s => %s (0x00000000)\n", interp_name, interp_name);
845 printf("\tnot a dynamic executable\n");
847 for (cur = lib_list; cur; cur = cur->next) {
850 if (cur->path && cur->path != not_found) {