Move dlsym and dladdr implementation to linker.cpp
Bug: http://b/25716705 Bug: http://b/22865643 Change-Id: If22fc1eda219f676b5fcc06490f7901d21d1749c
This commit is contained in:
Dimitry Ivanov
parent
9d8632e1a7
commit
4a2c5aa30c
@ -16,12 +16,10 @@
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#include "linker.h"
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#include <dlfcn.h>
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#include <pthread.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <android/dlext.h>
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#include <android/api-level.h>
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#include <bionic/pthread_internal.h>
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@ -70,8 +68,7 @@ void android_update_LD_LIBRARY_PATH(const char* ld_library_path) {
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static void* dlopen_ext(const char* filename, int flags,
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const android_dlextinfo* extinfo, void* caller_addr) {
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ScopedPthreadMutexLocker locker(&g_dl_mutex);
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soinfo* caller = find_containing_library(caller_addr);
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soinfo* result = do_dlopen(filename, flags, extinfo, caller);
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soinfo* result = do_dlopen(filename, flags, extinfo, caller_addr);
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if (result == nullptr) {
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__bionic_format_dlerror("dlopen failed", linker_get_error_buffer());
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return nullptr;
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@ -92,71 +89,20 @@ void* dlopen(const char* filename, int flags) {
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extern android_namespace_t* g_anonymous_namespace;
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void* dlsym(void* handle, const char* symbol) {
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ScopedPthreadMutexLocker locker(&g_dl_mutex);
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// TODO(dimitry): move (most of) the code below to linker.cpp
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#if !defined(__LP64__)
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if (handle == nullptr) {
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__bionic_format_dlerror("dlsym library handle is null", nullptr);
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return nullptr;
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}
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#endif
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if (symbol == nullptr) {
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__bionic_format_dlerror("dlsym symbol name is null", nullptr);
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return nullptr;
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}
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soinfo* found = nullptr;
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const ElfW(Sym)* sym = nullptr;
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void* caller_addr = __builtin_return_address(0);
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soinfo* caller = find_containing_library(caller_addr);
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android_namespace_t* ns = caller != nullptr ? caller->get_namespace() : g_anonymous_namespace;
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if (handle == RTLD_DEFAULT || handle == RTLD_NEXT) {
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sym = dlsym_linear_lookup(ns, symbol, &found, caller, handle);
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} else {
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sym = dlsym_handle_lookup(reinterpret_cast<soinfo*>(handle), &found, symbol);
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}
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if (sym != nullptr) {
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unsigned bind = ELF_ST_BIND(sym->st_info);
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if ((bind == STB_GLOBAL || bind == STB_WEAK) && sym->st_shndx != 0) {
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return reinterpret_cast<void*>(found->resolve_symbol_address(sym));
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}
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__bionic_format_dlerror("symbol found but not global", symbol);
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return nullptr;
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} else {
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__bionic_format_dlerror("undefined symbol", symbol);
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ScopedPthreadMutexLocker locker(&g_dl_mutex);
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void* result;
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if (!do_dlsym(handle, symbol, nullptr, caller_addr, &result)) {
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__bionic_format_dlerror(linker_get_error_buffer(), nullptr);
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return nullptr;
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}
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return result;
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}
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int dladdr(const void* addr, Dl_info* info) {
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ScopedPthreadMutexLocker locker(&g_dl_mutex);
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// Determine if this address can be found in any library currently mapped.
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soinfo* si = find_containing_library(addr);
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if (si == nullptr) {
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return 0;
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}
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memset(info, 0, sizeof(Dl_info));
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info->dli_fname = si->get_realpath();
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// Address at which the shared object is loaded.
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info->dli_fbase = reinterpret_cast<void*>(si->base);
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// Determine if any symbol in the library contains the specified address.
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ElfW(Sym)* sym = si->find_symbol_by_address(addr);
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if (sym != nullptr) {
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info->dli_sname = si->get_string(sym->st_name);
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info->dli_saddr = reinterpret_cast<void*>(si->resolve_symbol_address(sym));
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}
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return 1;
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return do_dladdr(addr, info);
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}
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int dlclose(void* handle) {
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@ -27,7 +27,6 @@
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*/
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#include <android/api-level.h>
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#include <dlfcn.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <inttypes.h>
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@ -891,20 +890,23 @@ soinfo::soinfo(android_namespace_t* ns, const char* realpath,
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this->namespace_ = ns;
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}
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static uint32_t calculate_elf_hash(const char* name) {
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const uint8_t* name_bytes = reinterpret_cast<const uint8_t*>(name);
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uint32_t h = 0, g;
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while (*name_bytes) {
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h = (h << 4) + *name_bytes++;
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g = h & 0xf0000000;
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h ^= g;
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h ^= g >> 24;
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}
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return h;
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}
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uint32_t SymbolName::elf_hash() {
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if (!has_elf_hash_) {
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const uint8_t* name = reinterpret_cast<const uint8_t*>(name_);
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uint32_t h = 0, g;
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while (*name) {
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h = (h << 4) + *name++;
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g = h & 0xf0000000;
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h ^= g;
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h ^= g >> 24;
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}
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elf_hash_ = h;
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elf_hash_ = calculate_elf_hash(name_);
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has_elf_hash_ = true;
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}
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@ -1243,7 +1245,8 @@ static bool walk_dependencies_tree(soinfo* root_soinfos[], size_t root_soinfos_s
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static const ElfW(Sym)* dlsym_handle_lookup(soinfo* root, soinfo* skip_until,
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soinfo** found, SymbolName& symbol_name) {
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soinfo** found, SymbolName& symbol_name,
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const version_info* vi) {
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const ElfW(Sym)* result = nullptr;
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bool skip_lookup = skip_until != nullptr;
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@ -1253,7 +1256,7 @@ static const ElfW(Sym)* dlsym_handle_lookup(soinfo* root, soinfo* skip_until,
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return true;
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}
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if (!current_soinfo->find_symbol_by_name(symbol_name, nullptr, &result)) {
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if (!current_soinfo->find_symbol_by_name(symbol_name, vi, &result)) {
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result = nullptr;
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return false;
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}
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@ -1269,9 +1272,17 @@ static const ElfW(Sym)* dlsym_handle_lookup(soinfo* root, soinfo* skip_until,
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return result;
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}
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static const ElfW(Sym)* dlsym_linear_lookup(android_namespace_t* ns,
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const char* name,
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const version_info* vi,
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soinfo** found,
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soinfo* caller,
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void* handle);
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// This is used by dlsym(3). It performs symbol lookup only within the
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// specified soinfo object and its dependencies in breadth first order.
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const ElfW(Sym)* dlsym_handle_lookup(soinfo* si, soinfo** found, const char* name) {
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static const ElfW(Sym)* dlsym_handle_lookup(soinfo* si, soinfo** found,
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const char* name, const version_info* vi) {
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// According to man dlopen(3) and posix docs in the case when si is handle
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// of the main executable we need to search not only in the executable and its
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// dependencies but also in all libraries loaded with RTLD_GLOBAL.
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@ -1280,11 +1291,11 @@ const ElfW(Sym)* dlsym_handle_lookup(soinfo* si, soinfo** found, const char* nam
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// libraries and they are loaded in breath-first (correct) order we can just execute
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// dlsym(RTLD_DEFAULT, ...); instead of doing two stage lookup.
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if (si == somain) {
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return dlsym_linear_lookup(&g_default_namespace, name, found, nullptr, RTLD_DEFAULT);
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return dlsym_linear_lookup(&g_default_namespace, name, vi, found, nullptr, RTLD_DEFAULT);
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}
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SymbolName symbol_name(name);
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return dlsym_handle_lookup(si, nullptr, found, symbol_name);
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return dlsym_handle_lookup(si, nullptr, found, symbol_name, vi);
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}
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/* This is used by dlsym(3) to performs a global symbol lookup. If the
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@ -1292,11 +1303,12 @@ const ElfW(Sym)* dlsym_handle_lookup(soinfo* si, soinfo** found, const char* nam
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beginning of the global solist. Otherwise the search starts at the
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specified soinfo (for RTLD_NEXT).
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*/
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const ElfW(Sym)* dlsym_linear_lookup(android_namespace_t* ns,
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const char* name,
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soinfo** found,
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soinfo* caller,
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void* handle) {
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static const ElfW(Sym)* dlsym_linear_lookup(android_namespace_t* ns,
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const char* name,
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const version_info* vi,
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soinfo** found,
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soinfo* caller,
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void* handle) {
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SymbolName symbol_name(name);
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soinfo::soinfo_list_t& soinfo_list = ns->soinfo_list();
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@ -1322,7 +1334,7 @@ const ElfW(Sym)* dlsym_linear_lookup(android_namespace_t* ns,
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continue;
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}
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if (!si->find_symbol_by_name(symbol_name, nullptr, &s)) {
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if (!si->find_symbol_by_name(symbol_name, vi, &s)) {
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return nullptr;
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}
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@ -1338,7 +1350,7 @@ const ElfW(Sym)* dlsym_linear_lookup(android_namespace_t* ns,
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if (s == nullptr && caller != nullptr &&
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(caller->get_rtld_flags() & RTLD_GLOBAL) == 0) {
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return dlsym_handle_lookup(caller->get_local_group_root(),
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(handle == RTLD_NEXT) ? caller : nullptr, found, symbol_name);
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(handle == RTLD_NEXT) ? caller : nullptr, found, symbol_name, vi);
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}
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if (s != nullptr) {
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@ -2176,6 +2188,14 @@ static void soinfo_unload(soinfo* root) {
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}
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}
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static std::string symbol_display_name(const char* sym_name, const char* sym_ver) {
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if (sym_ver == nullptr) {
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return sym_name;
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}
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return std::string(sym_name) + "@" + sym_ver;
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}
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void do_android_get_LD_LIBRARY_PATH(char* buffer, size_t buffer_size) {
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// Use basic string manipulation calls to avoid snprintf.
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// snprintf indirectly calls pthread_getspecific to get the size of a buffer.
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@ -2203,7 +2223,10 @@ void do_android_update_LD_LIBRARY_PATH(const char* ld_library_path) {
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parse_LD_LIBRARY_PATH(ld_library_path);
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}
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soinfo* do_dlopen(const char* name, int flags, const android_dlextinfo* extinfo, soinfo *caller) {
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soinfo* do_dlopen(const char* name, int flags, const android_dlextinfo* extinfo,
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void* caller_addr) {
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soinfo* const caller = find_containing_library(caller_addr);
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if ((flags & ~(RTLD_NOW|RTLD_LAZY|RTLD_LOCAL|RTLD_GLOBAL|RTLD_NODELETE|RTLD_NOLOAD)) != 0) {
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DL_ERR("invalid flags to dlopen: %x", flags);
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return nullptr;
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@ -2249,6 +2272,79 @@ soinfo* do_dlopen(const char* name, int flags, const android_dlextinfo* extinfo,
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return si;
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}
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int do_dladdr(const void* addr, Dl_info* info) {
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// Determine if this address can be found in any library currently mapped.
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soinfo* si = find_containing_library(addr);
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if (si == nullptr) {
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return 0;
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}
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memset(info, 0, sizeof(Dl_info));
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info->dli_fname = si->get_realpath();
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// Address at which the shared object is loaded.
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info->dli_fbase = reinterpret_cast<void*>(si->base);
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// Determine if any symbol in the library contains the specified address.
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ElfW(Sym)* sym = si->find_symbol_by_address(addr);
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if (sym != nullptr) {
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info->dli_sname = si->get_string(sym->st_name);
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info->dli_saddr = reinterpret_cast<void*>(si->resolve_symbol_address(sym));
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}
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return 1;
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}
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bool do_dlsym(void* handle, const char* sym_name, const char* sym_ver,
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void* caller_addr, void** symbol) {
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#if !defined(__LP64__)
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if (handle == nullptr) {
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DL_ERR("dlsym failed: library handle is null");
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return false;
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}
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#endif
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if (sym_name == nullptr) {
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DL_ERR("dlsym failed: symbol name is null");
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return false;
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}
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soinfo* found = nullptr;
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const ElfW(Sym)* sym = nullptr;
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soinfo* caller = find_containing_library(caller_addr);
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android_namespace_t* ns = caller != nullptr ? caller->get_namespace() : g_anonymous_namespace;
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version_info vi_instance;
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version_info* vi = nullptr;
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if (sym_ver != nullptr) {
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vi_instance.name = sym_name;
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vi_instance.elf_hash = calculate_elf_hash(sym_name);
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vi = &vi_instance;
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}
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if (handle == RTLD_DEFAULT || handle == RTLD_NEXT) {
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sym = dlsym_linear_lookup(ns, sym_name, vi, &found, caller, handle);
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} else {
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sym = dlsym_handle_lookup(reinterpret_cast<soinfo*>(handle), &found, sym_name, vi);
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}
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if (sym != nullptr) {
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uint32_t bind = ELF_ST_BIND(sym->st_info);
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if ((bind == STB_GLOBAL || bind == STB_WEAK) && sym->st_shndx != 0) {
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*symbol = reinterpret_cast<void*>(found->resolve_symbol_address(sym));
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return true;
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}
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DL_ERR("symbol \"%s\" found but not global", symbol_display_name(sym_name, sym_ver).c_str());
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return false;
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}
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DL_ERR("undefined symbol: %s", symbol_display_name(sym_name, sym_ver).c_str());
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return false;
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}
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void do_dlclose(soinfo* si) {
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ProtectedDataGuard guard;
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soinfo_unload(si);
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@ -29,6 +29,7 @@
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#ifndef _LINKER_H_
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#define _LINKER_H_
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#include <dlfcn.h>
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#include <android/dlext.h>
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#include <elf.h>
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#include <inttypes.h>
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@ -135,7 +136,7 @@ class SymbolName {
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};
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struct version_info {
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version_info() : elf_hash(0), name(nullptr), target_si(nullptr) {}
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constexpr version_info() : elf_hash(0), name(nullptr), target_si(nullptr) {}
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uint32_t elf_hash;
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const char* name;
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@ -422,17 +423,15 @@ soinfo* get_libdl_info();
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void do_android_get_LD_LIBRARY_PATH(char*, size_t);
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void do_android_update_LD_LIBRARY_PATH(const char* ld_library_path);
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soinfo* do_dlopen(const char* name, int flags, const android_dlextinfo* extinfo, soinfo *caller);
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soinfo* do_dlopen(const char* name, int flags, const android_dlextinfo* extinfo, void* caller_addr);
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void do_dlclose(soinfo* si);
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int do_dl_iterate_phdr(int (*cb)(dl_phdr_info* info, size_t size, void* data), void* data);
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const ElfW(Sym)* dlsym_linear_lookup(android_namespace_t* ns, const char* name, soinfo** found,
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soinfo* caller, void* handle);
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bool do_dlsym(void* handle, const char* sym_name, const char* sym_ver,
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void* caller_addr, void** symbol);
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soinfo* find_containing_library(const void* addr);
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const ElfW(Sym)* dlsym_handle_lookup(soinfo* si, soinfo** found, const char* name);
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int do_dladdr(const void* addr, Dl_info* info);
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void debuggerd_init();
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extern "C" abort_msg_t* g_abort_message;
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@ -760,7 +760,7 @@ TEST(dlfcn, dlsym_failures) {
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// so it can be distinguished from the NULL handle.
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sym = dlsym(nullptr, "test");
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ASSERT_TRUE(sym == nullptr);
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ASSERT_SUBSTR("dlsym library handle is null", dlerror());
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ASSERT_STREQ("dlsym failed: library handle is null", dlerror());
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#endif
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// NULL symbol name.
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@ -768,7 +768,7 @@ TEST(dlfcn, dlsym_failures) {
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// glibc marks this parameter non-null and SEGVs if you cheat.
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sym = dlsym(self, nullptr);
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ASSERT_TRUE(sym == nullptr);
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ASSERT_SUBSTR("", dlerror());
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ASSERT_STREQ("dlsym failed: symbol name is null", dlerror());
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#endif
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// Symbol that doesn't exist.
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