generic-library/bionic
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Support DT_RUNPATH in the linker.

Browse Source 
Only $ORIGIN substitution is supported, but not linux-specific $LIB
or $PLATFORM.

Change-Id: I5814a016c7c91afba080230a547a863686e7c2b9
This commit is contained in:
Evgenii Stepanov
2015-06-10 13:38:39 -07:00
parent f3463db7eb
commit 6865082ca6
7 changed files with 182 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

96
linker/linker.cpp
View File

@@ -97,6 +97,14 @@ __LIBC_HIDDEN__ int g_ld_debug_verbosity;
__LIBC_HIDDEN__ abort_msg_t* g_abort_message = nullptr; // For debuggerd.
static std::string dirname(const char *path) {
const char* last_slash = strrchr(path, '/');
if (last_slash == path) return "/";
else if (last_slash == nullptr) return ".";
else
return std::string(path, last_slash - path);
}
#if STATS
struct linker_stats_t {
int count[kRelocMax];
@@ -308,6 +316,38 @@ static void parse_LD_LIBRARY_PATH(const char* path) {
parse_path(path, ":", &g_ld_library_paths);
}
void soinfo::set_dt_runpath(const char* path) {
if (!has_min_version(2)) return;
parse_path(path, ":", &dt_runpath_);
std::string origin = dirname(get_realpath());
// FIXME: add $LIB and $PLATFORM.
std::pair<std::string, std::string> substs[] = {{"ORIGIN", origin}};
for (std::string& s : dt_runpath_) {
size_t pos = 0;
while (pos < s.size()) {
pos = s.find("$", pos);
if (pos == std::string::npos) break;
for (const auto& subst : substs) {
const std::string& token = subst.first;
const std::string& replacement = subst.second;
if (s.substr(pos + 1, token.size()) == token) {
s.replace(pos, token.size() + 1, replacement);
// -1 to compensate for the ++pos below.
pos += replacement.size() - 1;
break;
} else if (s.substr(pos + 1, token.size() + 2) == "{" + token + "}") {
s.replace(pos, token.size() + 3, replacement);
pos += replacement.size() - 1;
break;
}
}
// Skip $ in case it did not match any of the known substitutions.
++pos;
}
}
}
static void parse_LD_PRELOAD(const char* path) {
// We have historically supported ':' as well as ' ' in LD_PRELOAD.
parse_path(path, " :", &g_ld_preload_names);
@@ -1161,8 +1201,9 @@ static int open_library_on_default_path(const char* name, off64_t* file_offset)
return -1;
}
static int open_library_on_ld_library_path(const char* name, off64_t* file_offset) {
for (const auto& path_str : g_ld_library_paths) {
static int open_library_on_paths(const char* name, off64_t* file_offset,
const std::vector<std::string>& paths) {
for (const auto& path_str : paths) {
char buf[512];
const char* const path = path_str.c_str();
if (!format_path(buf, sizeof(buf), path, name)) {
@@ -1189,7 +1230,7 @@ static int open_library_on_ld_library_path(const char* name, off64_t* file_offse
return -1;
}
static int open_library(const char* name, off64_t* file_offset) {
static int open_library(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.
@@ -1209,7 +1250,10 @@ static int open_library(const char* name, off64_t* file_offset) {
}
// Otherwise we try LD_LIBRARY_PATH first, and fall back to the built-in well known paths.
int fd = open_library_on_ld_library_path(name, file_offset);
int fd = open_library_on_paths(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());
}
if (fd == -1) {
fd = open_library_on_default_path(name, file_offset);
}
@@ -1319,8 +1363,8 @@ static soinfo* load_library(int fd, off64_t file_offset,
return si;
}
static soinfo* load_library(LoadTaskList& load_tasks,
const char* name, int rtld_flags,
static soinfo* load_library(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) {
off64_t file_offset = 0;
@@ -1332,7 +1376,7 @@ static soinfo* load_library(LoadTaskList& load_tasks,
// Open the file.
off64_t file_offset;
int fd = open_library(name, &file_offset);
int fd = open_library(name, needed_by, &file_offset);
if (fd == -1) {
DL_ERR("library \"%s\" not found", name);
return nullptr;
@@ -1358,14 +1402,15 @@ static soinfo *find_loaded_library_by_soname(const char* name) {
}
static soinfo* find_library_internal(LoadTaskList& load_tasks, const char* name,
int rtld_flags, const android_dlextinfo* extinfo) {
soinfo* needed_by, int rtld_flags,
const android_dlextinfo* extinfo) {
soinfo* si = find_loaded_library_by_soname(name);
// Library might still be loaded, the accurate detection
// of this fact is done by load_library.
if (si == nullptr) {
TRACE("[ '%s' has not been found by soname. Trying harder...]", name);
si = load_library(load_tasks, name, rtld_flags, extinfo);
si = load_library(load_tasks, name, needed_by, rtld_flags, extinfo);
}
return si;
@@ -1434,13 +1479,13 @@ static bool find_libraries(soinfo* start_with, const char* const library_names[]
// 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* si = find_library_internal(load_tasks, task->get_name(), rtld_flags, extinfo);
soinfo* needed_by = task->get_needed_by();
soinfo* si = find_library_internal(load_tasks, task->get_name(), needed_by,
rtld_flags, extinfo);
if (si == nullptr) {
return false;
}
soinfo* needed_by = task->get_needed_by();
if (needed_by != nullptr) {
needed_by->add_child(si);
}
@@ -2337,6 +2382,16 @@ soinfo::soinfo_list_t& soinfo::get_parents() {
return g_empty_list;
}
static std::vector<std::string> g_empty_runpath;
const std::vector<std::string>& soinfo::get_dt_runpath() const {
if (has_min_version(2)) {
return dt_runpath_;
}
return g_empty_runpath;
}
ElfW(Addr) soinfo::resolve_symbol_address(const ElfW(Sym)* s) const {
if (ELF_ST_TYPE(s->st_info) == STT_GNU_IFUNC) {
return call_ifunc_resolver(s->st_value + load_bias);
@@ -2833,6 +2888,10 @@ bool soinfo::prelink_image() {
verneed_cnt_ = d->d_un.d_val;
break;
case DT_RUNPATH:
// this is parsed after we have strtab initialized (see below).
break;
default:
if (!relocating_linker) {
DL_WARN("%s: unused DT entry: type %p arg %p", get_realpath(),
@@ -2866,12 +2925,17 @@ bool soinfo::prelink_image() {
// second pass - parse entries relying on strtab
for (ElfW(Dyn)* d = dynamic; d->d_tag != DT_NULL; ++d) {
if (d->d_tag == DT_SONAME) {
soname_ = get_string(d->d_un.d_val);
switch (d->d_tag) {
case DT_SONAME:
soname_ = get_string(d->d_un.d_val);
#if defined(__work_around_b_19059885__)
strlcpy(old_name_, soname_, sizeof(old_name_));
strlcpy(old_name_, soname_, sizeof(old_name_));
#endif
break;
break;
case DT_RUNPATH:
// FIXME: $LIB, $PLATFORM unsupported.
set_dt_runpath(get_string(d->d_un.d_val));
break;
}
}