Optimize dlopen from a zip file

This change makes dynamic linker reuse ZipArchiveHandles in
ld_library_path on dlopen to optimize the lookup of dt_needed
libraries.

Bug: http://b/21960534
Change-Id: I65f897910d46dd2ffabdcb0b7842db2f127eee30
This commit is contained in:
Dmitriy Ivanov
2015-09-28 16:38:31 -07:00
parent 8b279eadd3
commit b48275045d
4 changed files with 118 additions and 39 deletions

View File

@@ -41,6 +41,7 @@
#include <new>
#include <string>
#include <unordered_map>
#include <vector>
// Private C library headers.
@@ -1121,7 +1122,50 @@ ElfW(Sym)* soinfo::elf_addr_lookup(const void* addr) {
return nullptr;
}
static int open_library_in_zipfile(const char* const path,
class ZipArchiveCache {
public:
ZipArchiveCache() {}
~ZipArchiveCache();
bool get_or_open(const char* zip_path, ZipArchiveHandle* handle);
private:
DISALLOW_COPY_AND_ASSIGN(ZipArchiveCache);
std::unordered_map<std::string, ZipArchiveHandle> cache_;
};
bool ZipArchiveCache::get_or_open(const char* zip_path, ZipArchiveHandle* handle) {
std::string key(zip_path);
auto it = cache_.find(key);
if (it != cache_.end()) {
*handle = it->second;
return true;
}
int fd = TEMP_FAILURE_RETRY(open(zip_path, O_RDONLY | O_CLOEXEC));
if (fd == -1) {
return false;
}
if (OpenArchiveFd(fd, "", handle) != 0) {
// invalid zip-file (?)
close(fd);
return false;
}
cache_[key] = *handle;
return true;
}
ZipArchiveCache::~ZipArchiveCache() {
for (auto it : cache_) {
CloseArchive(it.second);
}
}
static int open_library_in_zipfile(ZipArchiveCache* zip_archive_cache,
const char* const path,
off64_t* file_offset) {
TRACE("Trying zip file open from path '%s'", path);
@@ -1150,16 +1194,12 @@ static int open_library_in_zipfile(const char* const path,
}
ZipArchiveHandle handle;
if (OpenArchiveFd(fd, "", &handle, false) != 0) {
if (!zip_archive_cache->get_or_open(zip_path, &handle)) {
// invalid zip-file (?)
close(fd);
return -1;
}
auto archive_guard = make_scope_guard([&]() {
CloseArchive(handle);
});
ZipEntry entry;
if (FindEntry(handle, ZipString(file_path), &entry) != 0) {
@@ -1205,7 +1245,8 @@ static int open_library_on_default_path(const char* name, off64_t* file_offset)
return -1;
}
static int open_library_on_paths(const char* name, off64_t* file_offset,
static int open_library_on_paths(ZipArchiveCache* zip_archive_cache,
const char* name, off64_t* file_offset,
const std::vector<std::string>& paths) {
for (const auto& path_str : paths) {
char buf[512];
@@ -1216,7 +1257,7 @@ static int open_library_on_paths(const char* name, off64_t* file_offset,
int fd = -1;
if (strstr(buf, kZipFileSeparator) != nullptr) {
fd = open_library_in_zipfile(buf, file_offset);
fd = open_library_in_zipfile(zip_archive_cache, buf, file_offset);
}
if (fd == -1) {
@@ -1234,13 +1275,15 @@ static int open_library_on_paths(const char* name, off64_t* file_offset,
return -1;
}
static int open_library(const char* name, soinfo *needed_by, off64_t* file_offset) {
static int open_library(ZipArchiveCache* zip_archive_cache,
const char* name, soinfo *needed_by,
off64_t* file_offset) {
TRACE("[ opening %s ]", name);
// If the name contains a slash, we should attempt to open it directly and not search the paths.
if (strchr(name, '/') != nullptr) {
if (strstr(name, kZipFileSeparator) != nullptr) {
int fd = open_library_in_zipfile(name, file_offset);
int fd = open_library_in_zipfile(zip_archive_cache, name, file_offset);
if (fd != -1) {
return fd;
}
@@ -1254,13 +1297,15 @@ static int open_library(const char* name, soinfo *needed_by, off64_t* file_offse
}
// Otherwise we try LD_LIBRARY_PATH first, and fall back to the built-in well known paths.
int fd = open_library_on_paths(name, file_offset, g_ld_library_paths);
int fd = open_library_on_paths(zip_archive_cache, name, file_offset, g_ld_library_paths);
if (fd == -1 && needed_by) {
fd = open_library_on_paths(name, file_offset, needed_by->get_dt_runpath());
fd = open_library_on_paths(zip_archive_cache, name, file_offset, needed_by->get_dt_runpath());
}
if (fd == -1) {
fd = open_library_on_default_path(name, file_offset);
}
return fd;
}
@@ -1367,7 +1412,8 @@ static soinfo* load_library(int fd, off64_t file_offset,
return si;
}
static soinfo* load_library(LoadTaskList& load_tasks, const char* name,
static soinfo* load_library(ZipArchiveCache* zip_archive_cache,
LoadTaskList& load_tasks, const char* name,
soinfo* needed_by, int rtld_flags,
const android_dlextinfo* extinfo) {
if (extinfo != nullptr && (extinfo->flags & ANDROID_DLEXT_USE_LIBRARY_FD) != 0) {
@@ -1380,7 +1426,7 @@ static soinfo* load_library(LoadTaskList& load_tasks, const char* name,
// Open the file.
off64_t file_offset;
int fd = open_library(name, needed_by, &file_offset);
int fd = open_library(zip_archive_cache, name, needed_by, &file_offset);
if (fd == -1) {
DL_ERR("library \"%s\" not found", name);
return nullptr;
@@ -1427,7 +1473,8 @@ static bool find_loaded_library_by_soname(const char* name, soinfo** candidate)
return false;
}
static soinfo* find_library_internal(LoadTaskList& load_tasks, const char* name,
static soinfo* find_library_internal(ZipArchiveCache* zip_archive_cache,
LoadTaskList& load_tasks, const char* name,
soinfo* needed_by, int rtld_flags,
const android_dlextinfo* extinfo) {
soinfo* candidate;
@@ -1441,7 +1488,7 @@ static soinfo* find_library_internal(LoadTaskList& load_tasks, const char* name,
TRACE("[ '%s' find_loaded_library_by_soname returned false (*candidate=%s@%p). Trying harder...]",
name, candidate == nullptr ? "n/a" : candidate->get_realpath(), candidate);
soinfo* si = load_library(load_tasks, name, needed_by, rtld_flags, extinfo);
soinfo* si = load_library(zip_archive_cache, load_tasks, name, needed_by, rtld_flags, extinfo);
// In case we were unable to load the library but there
// is a candidate loaded under the same soname but different
@@ -1521,15 +1568,18 @@ static bool find_libraries(soinfo* start_with,
}
});
ZipArchiveCache zip_archive_cache;
// Step 1: load and pre-link all DT_NEEDED libraries in breadth first order.
for (LoadTask::unique_ptr task(load_tasks.pop_front());
task.get() != nullptr; task.reset(load_tasks.pop_front())) {
soinfo* needed_by = task->get_needed_by();
bool is_dt_needed = needed_by != nullptr && (needed_by != start_with || add_as_children);
soinfo* si = find_library_internal(load_tasks, task->get_name(), needed_by,
rtld_flags,
soinfo* si = find_library_internal(&zip_archive_cache, load_tasks,
task->get_name(), needed_by, rtld_flags,
is_dt_needed ? nullptr : extinfo);
if (si == nullptr) {
return false;
}