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|
/* vi: set sw=4 ts=4: */
/*
* A small little ldd implementation for uClibc
*
* Copyright (C) 2000-2006 Erik Andersen <andersen@uclibc.org>
*
* Several functions in this file (specifically, elf_find_section_type(),
* elf_find_phdr_type(), and elf_find_dynamic(), were stolen from elflib.c from
* elfvector (http://www.BitWagon.com/elfvector.html) by John F. Reiser
* <jreiser@BitWagon.com>, which is copyright 2000 BitWagon Software LLC
* (GPL2).
*
* Licensed under GPLv2 or later
*/
#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <stdint.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include "bswap.h"
#include "link.h"
#include "dl-defs.h"
/* makefile will include elf.h for us */
#ifdef DMALLOC
#include <dmalloc.h>
#endif
#if defined(__alpha__)
#define MATCH_MACHINE(x) (x == EM_ALPHA)
#define ELFCLASSM ELFCLASS64
#endif
#if defined(__arm__) || defined(__thumb__)
#define MATCH_MACHINE(x) (x == EM_ARM)
#define ELFCLASSM ELFCLASS32
#endif
#if defined(__avr32__)
#define MATCH_MACHINE(x) (x == EM_AVR32)
#define ELFCLASSM ELFCLASS32
#endif
#if defined(__s390__)
#define MATCH_MACHINE(x) (x == EM_S390)
#define ELFCLASSM ELFCLASS32
#endif
#if defined(__hppa__)
#define MATCH_MACHINE(x) (x == EM_PARISC)
#if defined(__LP64__)
#define ELFCLASSM ELFCLASS64
#else
#define ELFCLASSM ELFCLASS32
#endif
#endif
#if defined(__i386__)
#ifndef EM_486
#define MATCH_MACHINE(x) (x == EM_386)
#else
#define MATCH_MACHINE(x) (x == EM_386 || x == EM_486)
#endif
#define ELFCLASSM ELFCLASS32
#endif
#if defined(__ia64__)
#define MATCH_MACHINE(x) (x == EM_IA_64)
#define ELFCLASSM ELFCLASS64
#endif
#if defined(__mc68000__)
#define MATCH_MACHINE(x) (x == EM_68K)
#define ELFCLASSM ELFCLASS32
#endif
#if defined(__mips__)
#define MATCH_MACHINE(x) (x == EM_MIPS || x == EM_MIPS_RS3_LE)
#define ELFCLASSM ELFCLASS32
#endif
#if defined(__powerpc64__)
#define MATCH_MACHINE(x) (x == EM_PPC64)
#define ELFCLASSM ELFCLASS64
#elif defined(__powerpc__)
#define MATCH_MACHINE(x) (x == EM_PPC)
#define ELFCLASSM ELFCLASS32
#endif
#if defined(__sh__)
#define MATCH_MACHINE(x) (x == EM_SH)
#define ELFCLASSM ELFCLASS32
#endif
#if defined(__v850e__)
#define MATCH_MACHINE(x) ((x) == EM_V850 || (x) == EM_CYGNUS_V850)
#define ELFCLASSM ELFCLASS32
#endif
#if defined(__sparc__)
#define MATCH_MACHINE(x) ((x) == EM_SPARC || (x) == EM_SPARC32PLUS)
#define ELFCLASSM ELFCLASS32
#endif
#if defined(__cris__)
#define MATCH_MACHINE(x) (x == EM_CRIS)
#define ELFCLASSM ELFCLASS32
#endif
#if defined(__x86_64__)
#define MATCH_MACHINE(x) (x == EM_X86_64)
#define ELFCLASSM ELFCLASS64
#endif
#ifndef MATCH_MACHINE
# ifdef __linux__
# include <asm/elf.h>
# endif
# ifdef ELF_ARCH
# define MATCH_MACHINE(x) (x == ELF_ARCH)
# endif
# ifdef ELF_CLASS
# define ELFCLASSM ELF_CLASS
# endif
#endif
#ifndef MATCH_MACHINE
# warning "You really should add a MATCH_MACHINE() macro for your architecture"
#endif
#if __BYTE_ORDER == __LITTLE_ENDIAN
#define ELFDATAM ELFDATA2LSB
#elif __BYTE_ORDER == __BIG_ENDIAN
#define ELFDATAM ELFDATA2MSB
#endif
#ifndef UCLIBC_RUNTIME_PREFIX
# define UCLIBC_RUNTIME_PREFIX "/"
#endif
struct library {
char *name;
int resolved;
char *path;
struct library *next;
};
static struct library *lib_list = NULL;
static char not_found[] = "not found";
static char *interp_name = NULL;
static char *interp_dir = NULL;
static int byteswap;
static int interpreter_already_found = 0;
static __inline__ uint32_t byteswap32_to_host(uint32_t value)
{
if (byteswap == 1) {
return (bswap_32(value));
} else {
return (value);
}
}
static __inline__ uint64_t byteswap64_to_host(uint64_t value)
{
if (byteswap == 1) {
return (bswap_64(value));
} else {
return (value);
}
}
#if ELFCLASSM == ELFCLASS32
# define byteswap_to_host(x) byteswap32_to_host(x)
#else
# define byteswap_to_host(x) byteswap64_to_host(x)
#endif
static ElfW(Shdr) *elf_find_section_type(uint32_t key, ElfW(Ehdr) *ehdr)
{
int j;
ElfW(Shdr) *shdr;
shdr = (ElfW(Shdr) *) (ehdr->e_shoff + (char *)ehdr);
for (j = ehdr->e_shnum; --j >= 0; ++shdr) {
if (key == byteswap32_to_host(shdr->sh_type)) {
return shdr;
}
}
return NULL;
}
static ElfW(Phdr) *elf_find_phdr_type(uint32_t type, ElfW(Ehdr) *ehdr)
{
int j;
ElfW(Phdr) *phdr = (ElfW(Phdr) *) (ehdr->e_phoff + (char *)ehdr);
for (j = ehdr->e_phnum; --j >= 0; ++phdr) {
if (type == byteswap32_to_host(phdr->p_type)) {
return phdr;
}
}
return NULL;
}
/* Returns value if return_val==1, ptr otherwise */
static void *elf_find_dynamic(int64_t const key, ElfW(Dyn) *dynp,
ElfW(Ehdr) *ehdr, int return_val)
{
ElfW(Phdr) *pt_text = elf_find_phdr_type(PT_LOAD, ehdr);
unsigned tx_reloc = byteswap_to_host(pt_text->p_vaddr) - byteswap_to_host(pt_text->p_offset);
for (; DT_NULL != byteswap_to_host(dynp->d_tag); ++dynp) {
if (key == byteswap_to_host(dynp->d_tag)) {
if (return_val == 1)
return (void *)byteswap_to_host(dynp->d_un.d_val);
else
return (void *)(byteswap_to_host(dynp->d_un.d_val) - tx_reloc + (char *)ehdr);
}
}
return NULL;
}
static char *elf_find_rpath(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic)
{
ElfW(Dyn) *dyns;
for (dyns = dynamic; byteswap_to_host(dyns->d_tag) != DT_NULL; ++dyns) {
if (DT_RPATH == byteswap_to_host(dyns->d_tag)) {
char *strtab;
strtab = (char *)elf_find_dynamic(DT_STRTAB, dynamic, ehdr, 0);
return ((char *)strtab + byteswap_to_host(dyns->d_un.d_val));
}
}
return NULL;
}
int check_elf_header(ElfW(Ehdr) *const ehdr)
{
if (!ehdr || *(uint32_t*)ehdr != ELFMAG_U32
|| ehdr->e_ident[EI_CLASS] != ELFCLASSM
|| ehdr->e_ident[EI_VERSION] != EV_CURRENT
) {
return 1;
}
/* Check if the target endianness matches the host's endianness */
byteswap = 0;
#if __BYTE_ORDER == __LITTLE_ENDIAN
if (ehdr->e_ident[5] == ELFDATA2MSB)
byteswap = 1;
#elif __BYTE_ORDER == __BIG_ENDIAN
if (ehdr->e_ident[5] == ELFDATA2LSB)
byteswap = 1;
#else
#error Unknown host byte order!
#endif
/* Be very lazy, and only byteswap the stuff we use */
if (byteswap) {
ehdr->e_type = bswap_16(ehdr->e_type);
ehdr->e_phoff = byteswap_to_host(ehdr->e_phoff);
ehdr->e_shoff = byteswap_to_host(ehdr->e_shoff);
ehdr->e_phnum = bswap_16(ehdr->e_phnum);
ehdr->e_shnum = bswap_16(ehdr->e_shnum);
}
return 0;
}
#ifdef __LDSO_CACHE_SUPPORT__
static caddr_t cache_addr = NULL;
static size_t cache_size = 0;
int map_cache(void)
{
int fd;
struct stat st;
header_t *header;
libentry_t *libent;
int i, strtabsize;
if (cache_addr == (caddr_t) - 1)
return -1;
else if (cache_addr != NULL)
return 0;
if (stat(LDSO_CACHE, &st) || (fd = open(LDSO_CACHE, O_RDONLY, 0)) < 0) {
fprintf(stderr, "ldd: can't open cache '%s'\n", LDSO_CACHE);
cache_addr = (caddr_t) - 1; /* so we won't try again */
return -1;
}
cache_size = st.st_size;
cache_addr = mmap(0, cache_size, PROT_READ, MAP_SHARED, fd, 0);
close(fd);
if (cache_addr == MAP_FAILED) {
fprintf(stderr, "ldd: can't map cache '%s'\n", LDSO_CACHE);
return -1;
}
header = (header_t *) cache_addr;
if (cache_size < sizeof(header_t)
|| memcmp(header->magic, LDSO_CACHE_MAGIC, LDSO_CACHE_MAGIC_LEN)
|| memcmp(header->version, LDSO_CACHE_VER, LDSO_CACHE_VER_LEN)
|| cache_size < (sizeof(header_t) + header->nlibs * sizeof(libentry_t))
|| cache_addr[cache_size - 1] != '\0')
{
fprintf(stderr, "ldd: cache '%s' is corrupt\n", LDSO_CACHE);
goto fail;
}
strtabsize = cache_size - sizeof(header_t) - header->nlibs * sizeof(libentry_t);
libent = (libentry_t *) & header[1];
for (i = 0; i < header->nlibs; i++) {
if (libent[i].sooffset >= strtabsize || libent[i].liboffset >= strtabsize) {
fprintf(stderr, "ldd: cache '%s' is corrupt\n", LDSO_CACHE);
goto fail;
}
}
return 0;
fail:
munmap(cache_addr, cache_size);
cache_addr = (caddr_t) - 1;
return -1;
}
int unmap_cache(void)
{
if (cache_addr == NULL || cache_addr == (caddr_t) - 1)
return -1;
#if 1
munmap(cache_addr, cache_size);
cache_addr = NULL;
#endif
return 0;
}
#else
static __inline__ void map_cache(void)
{
}
static __inline__ void unmap_cache(void)
{
}
#endif
/* This function's behavior must exactly match that
* in uClibc/ldso/ldso/dl-elf.c */
static void search_for_named_library(char *name, char *result,
const char *path_list)
{
int i, count = 1;
char *path, *path_n;
struct stat filestat;
/* We need a writable copy of this string */
path = strdup(path_list);
if (!path) {
fprintf(stderr, "Out of memory!\n");
exit(EXIT_FAILURE);
}
/* Eliminate all double //s */
path_n = path;
while ((path_n = strstr(path_n, "//"))) {
i = strlen(path_n);
memmove(path_n, path_n + 1, i - 1);
*(path_n + i - 1) = '\0';
}
/* Replace colons with zeros in path_list and count them */
for (i = strlen(path); i > 0; i--) {
if (path[i] == ':') {
path[i] = 0;
count++;
}
}
path_n = path;
for (i = 0; i < count; i++) {
strcpy(result, path_n);
strcat(result, "/");
strcat(result, name);
if (stat(result, &filestat) == 0 && filestat.st_mode & S_IRUSR) {
free(path);
return;
}
path_n += (strlen(path_n) + 1);
}
free(path);
*result = '\0';
}
void locate_library_file(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic, int is_suid,
struct library *lib)
{
char *buf;
char *path;
struct stat filestat;
/* If this is a fully resolved name, our job is easy */
if (stat(lib->name, &filestat) == 0) {
lib->path = strdup(lib->name);
return;
}
/* We need some elbow room here. Make some room... */
buf = malloc(1024);
if (!buf) {
fprintf(stderr, "Out of memory!\n");
exit(EXIT_FAILURE);
}
/* This function must match the behavior of _dl_load_shared_library
* in readelflib1.c or things won't work out as expected... */
/* The ABI specifies that RPATH is searched first, so do that now. */
path = elf_find_rpath(ehdr, dynamic);
if (path) {
search_for_named_library(lib->name, buf, path);
if (*buf != '\0') {
lib->path = buf;
return;
}
}
/* Next check LD_{ELF_}LIBRARY_PATH if specified and allowed.
* Since this app doesn't actually run an executable I will skip
* the suid check, and just use LD_{ELF_}LIBRARY_PATH if set */
if (is_suid == 1)
path = NULL;
else
path = getenv("LD_LIBRARY_PATH");
if (path) {
search_for_named_library(lib->name, buf, path);
if (*buf != '\0') {
lib->path = buf;
return;
}
}
#ifdef __LDSO_CACHE_SUPPORT__
if (cache_addr != NULL && cache_addr != (caddr_t) - 1) {
int i;
header_t *header = (header_t *) cache_addr;
libentry_t *libent = (libentry_t *) & header[1];
char *strs = (char *)&libent[header->nlibs];
for (i = 0; i < header->nlibs; i++) {
if ((libent[i].flags == LIB_ELF ||
libent[i].flags == LIB_ELF_LIBC0 ||
libent[i].flags == LIB_ELF_LIBC5) &&
strcmp(lib->name, strs + libent[i].sooffset) == 0)
{
lib->path = strdup(strs + libent[i].liboffset);
return;
}
}
}
#endif
/* Next look for libraries wherever the shared library
* loader was installed -- this is usually where we
* should find things... */
if (interp_dir) {
search_for_named_library(lib->name, buf, interp_dir);
if (*buf != '\0') {
lib->path = buf;
return;
}
}
/* Lastly, search the standard list of paths for the library.
This list must exactly match the list in uClibc/ldso/ldso/dl-elf.c */
path = UCLIBC_RUNTIME_PREFIX "lib:" UCLIBC_RUNTIME_PREFIX "usr/lib"
#ifndef __LDSO_CACHE_SUPPORT__
":" UCLIBC_RUNTIME_PREFIX "usr/X11R6/lib"
#endif
;
search_for_named_library(lib->name, buf, path);
if (*buf != '\0') {
lib->path = buf;
} else {
free(buf);
lib->path = not_found;
}
}
static int add_library(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic, int is_setuid, char *s)
{
char *tmp, *tmp1, *tmp2;
struct library *cur, *newlib = lib_list;
if (!s || !strlen(s))
return 1;
tmp = s;
while (*tmp) {
if (*tmp == '/')
s = tmp + 1;
tmp++;
}
/* We add ldso elsewhere */
if (interpreter_already_found && (tmp = strrchr(interp_name, '/')) != NULL) {
int len = strlen(interp_dir);
if (strcmp(s, interp_name + 1 + len) == 0)
return 1;
}
for (cur = lib_list; cur; cur = cur->next) {
/* Check if this library is already in the list */
tmp1 = tmp2 = cur->name;
while (*tmp1) {
if (*tmp1 == '/')
tmp2 = tmp1 + 1;
tmp1++;
}
if (strcmp(tmp2, s) == 0) {
/*printf("find_elf_interpreter is skipping '%s' (already in list)\n", cur->name); */
return 0;
}
}
/* Ok, this lib needs to be added to the list */
newlib = malloc(sizeof(struct library));
if (!newlib)
return 1;
newlib->name = malloc(strlen(s) + 1);
strcpy(newlib->name, s);
newlib->resolved = 0;
newlib->path = NULL;
newlib->next = NULL;
/* Now try and locate where this library might be living... */
locate_library_file(ehdr, dynamic, is_setuid, newlib);
/*printf("add_library is adding '%s' to '%s'\n", newlib->name, newlib->path); */
if (!lib_list) {
lib_list = newlib;
} else {
for (cur = lib_list; cur->next; cur = cur->next) ; /* nothing */
cur->next = newlib;
}
return 0;
}
static void find_needed_libraries(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic, int is_setuid)
{
ElfW(Dyn) *dyns;
for (dyns = dynamic; byteswap_to_host(dyns->d_tag) != DT_NULL; ++dyns) {
if (DT_NEEDED == byteswap_to_host(dyns->d_tag)) {
char *strtab;
strtab = (char *)elf_find_dynamic(DT_STRTAB, dynamic, ehdr, 0);
add_library(ehdr, dynamic, is_setuid, (char *)strtab + byteswap_to_host(dyns->d_un.d_val));
}
}
}
static struct library *find_elf_interpreter(ElfW(Ehdr) *ehdr)
{
ElfW(Phdr) *phdr;
if (interpreter_already_found == 1)
return NULL;
phdr = elf_find_phdr_type(PT_INTERP, ehdr);
if (phdr) {
struct library *cur, *newlib = NULL;
char *s = (char *)ehdr + byteswap_to_host(phdr->p_offset);
char *tmp, *tmp1;
interp_name = strdup(s);
interp_dir = strdup(s);
tmp = strrchr(interp_dir, '/');
if (*tmp)
*tmp = '\0';
else {
free(interp_dir);
interp_dir = interp_name;
}
tmp1 = tmp = s;
while (*tmp) {
if (*tmp == '/')
tmp1 = tmp + 1;
tmp++;
}
for (cur = lib_list; cur; cur = cur->next) {
/* Check if this library is already in the list */
if (strcmp(cur->name, tmp1) == 0) {
/*printf("find_elf_interpreter is replacing '%s' (already in list)\n", cur->name); */
newlib = cur;
free(newlib->name);
if (newlib->path != not_found) {
free(newlib->path);
}
newlib->name = NULL;
newlib->path = NULL;
return NULL;
}
}
if (newlib == NULL)
newlib = malloc(sizeof(struct library));
if (!newlib)
return NULL;
newlib->name = malloc(strlen(s) + 1);
strcpy(newlib->name, s);
newlib->path = strdup(newlib->name);
newlib->resolved = 1;
newlib->next = NULL;
#if 0
/*printf("find_elf_interpreter is adding '%s' to '%s'\n", newlib->name, newlib->path); */
if (!lib_list) {
lib_list = newlib;
} else {
for (cur = lib_list; cur->next; cur = cur->next) ; /* nothing */
cur->next = newlib;
}
#endif
interpreter_already_found = 1;
return newlib;
}
return NULL;
}
/* map the .so, and locate interesting pieces */
/*
#warning "There may be two warnings here about vfork() clobbering, ignore them"
*/
int find_dependancies(char *filename)
{
int is_suid = 0;
FILE *thefile;
struct library *interp;
struct stat statbuf;
ElfW(Ehdr) *ehdr = NULL;
ElfW(Shdr) *dynsec = NULL;
ElfW(Dyn) *dynamic = NULL;
if (filename == not_found)
return 0;
if (!filename) {
fprintf(stderr, "No filename specified.\n");
return -1;
}
if (!(thefile = fopen(filename, "r"))) {
perror(filename);
return -1;
}
if (fstat(fileno(thefile), &statbuf) < 0) {
perror(filename);
fclose(thefile);
return -1;
}
if ((size_t) statbuf.st_size < sizeof(ElfW(Ehdr)))
goto foo;
if (!S_ISREG(statbuf.st_mode))
goto foo;
/* mmap the file to make reading stuff from it effortless */
ehdr = mmap(0, statbuf.st_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fileno(thefile), 0);
if (ehdr == MAP_FAILED) {
fclose(thefile);
fprintf(stderr, "Out of memory!\n");
return -1;
}
foo:
fclose(thefile);
/* Check if this looks like a legit ELF file */
if (check_elf_header(ehdr)) {
fprintf(stderr, "%s: not an ELF file.\n", filename);
return -1;
}
/* Check if this is the right kind of ELF file */
if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) {
fprintf(stderr, "%s: not a dynamic executable\n", filename);
return -1;
}
if (ehdr->e_type == ET_EXEC || ehdr->e_type == ET_DYN) {
if (statbuf.st_mode & S_ISUID)
is_suid = 1;
if ((statbuf.st_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP))
is_suid = 1;
/* FIXME */
if (is_suid)
fprintf(stderr, "%s: is setuid\n", filename);
}
interpreter_already_found = 0;
interp = find_elf_interpreter(ehdr);
#ifdef __LDSO_LDD_SUPPORT__
if (interp
&& (ehdr->e_type == ET_EXEC || ehdr->e_type == ET_DYN)
&& ehdr->e_ident[EI_CLASS] == ELFCLASSM
&& ehdr->e_ident[EI_DATA] == ELFDATAM
&& ehdr->e_ident[EI_VERSION] == EV_CURRENT
&& MATCH_MACHINE(ehdr->e_machine))
{
struct stat statbuf;
if (stat(interp->path, &statbuf) == 0 && S_ISREG(statbuf.st_mode)) {
pid_t pid;
int status;
static const char *const environment[] = {
"PATH=/usr/bin:/bin:/usr/sbin:/sbin",
"SHELL=/bin/sh",
"LD_TRACE_LOADED_OBJECTS=1",
NULL
};
if ((pid = vfork()) == 0) {
/* Cool, it looks like we should be able to actually
* run this puppy. Do so now... */
execle(filename, filename, NULL, environment);
_exit(0xdead);
}
/* Wait till it returns */
waitpid(pid, &status, 0);
if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
return 1;
}
/* If the exec failed, we fall through to trying to find
* all the needed libraries ourselves by rummaging about
* in the ELF headers... */
}
}
#endif
dynsec = elf_find_section_type(SHT_DYNAMIC, ehdr);
if (dynsec) {
dynamic = (ElfW(Dyn) *) (byteswap_to_host(dynsec->sh_offset) + (char *)ehdr);
find_needed_libraries(ehdr, dynamic, is_suid);
}
return 0;
}
int main(int argc, char **argv)
{
int multi = 0;
int got_em_all = 1;
char *filename = NULL;
struct library *cur;
if (argc < 2) {
fprintf(stderr, "ldd: missing file arguments\n"
"Try `ldd --help' for more information.\n");
exit(EXIT_FAILURE);
}
if (argc > 2)
multi++;
while (--argc > 0) {
++argv;
if (strcmp(*argv, "--") == 0) {
/* Ignore "--" */
continue;
}
if (strcmp(*argv, "--help") == 0 || strcmp(*argv, "-h") == 0) {
fprintf(stderr, "Usage: ldd [OPTION]... FILE...\n"
"\t--help\t\tprint this help and exit\n");
exit(EXIT_SUCCESS);
}
filename = *argv;
if (!filename) {
fprintf(stderr, "No filename specified.\n");
exit(EXIT_FAILURE);
}
if (multi) {
printf("%s:\n", *argv);
}
map_cache();
if (find_dependancies(filename) != 0)
continue;
while (got_em_all) {
got_em_all = 0;
/* Keep walking the list till everybody is resolved */
for (cur = lib_list; cur; cur = cur->next) {
if (cur->resolved == 0 && cur->path) {
got_em_all = 1;
printf("checking sub-depends for '%s'\n", cur->path);
find_dependancies(cur->path);
cur->resolved = 1;
}
}
}
unmap_cache();
/* Print the list */
got_em_all = 0;
for (cur = lib_list; cur; cur = cur->next) {
got_em_all = 1;
printf("\t%s => %s (0x00000000)\n", cur->name, cur->path);
}
if (interp_name && interpreter_already_found == 1)
printf("\t%s => %s (0x00000000)\n", interp_name, interp_name);
else
printf("\tnot a dynamic executable\n");
for (cur = lib_list; cur; cur = cur->next) {
free(cur->name);
cur->name = NULL;
if (cur->path && cur->path != not_found) {
free(cur->path);
cur->path = NULL;
}
}
lib_list = NULL;
}
return 0;
}
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