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Add RTLD_NOLOAD support and some related changes.

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* Aligned RTLD_ values with glibc for lp64
 * dlopen supports RTLD_NOLOAD flag
 * soinfo_unload calls find_library(.., RTLD_NOLOAD)
   instead of naive find_loaded_library_by_name()
 * dlopen changed to add child to caller soinfo instead
   of somain.

Bug: https://code.google.com/p/android/issues/detail?id=64069
Change-Id: I1a65f2c34f3e0edc6d2c41a2e408b58195feb640
This commit is contained in:
Dmitriy Ivanov
2014-05-19 15:06:58 -07:00
parent 0b9a72ce11
commit b648a8a57e
7 changed files with 120 additions and 32 deletions
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22
linker/dlfcn.cpp
View File

@@ -65,10 +65,10 @@ void android_update_LD_LIBRARY_PATH(const char* ld_library_path) {
do_android_update_LD_LIBRARY_PATH(ld_library_path);
}
void* android_dlopen_ext(const char* filename, int flags, const android_dlextinfo* extinfo)
{
static void* dlopen_ext(const char* filename, int flags, const android_dlextinfo* extinfo, const void* caller_addr) {
ScopedPthreadMutexLocker locker(&g_dl_mutex);
soinfo* result = do_dlopen(filename, flags, extinfo);
soinfo* caller_soinfo = find_containing_library(caller_addr);
soinfo* result = do_dlopen(filename, flags, caller_soinfo, extinfo);
if (result == NULL) {
__bionic_format_dlerror("dlopen failed", linker_get_error_buffer());
return NULL;
@@ -76,8 +76,14 @@ void* android_dlopen_ext(const char* filename, int flags, const android_dlextinf
return result;
}
void* android_dlopen_ext(const char* filename, int flags, const android_dlextinfo* extinfo) {
void* caller_addr = __builtin_return_address(0);
return dlopen_ext(filename, flags, extinfo, caller_addr);
}
void* dlopen(const char* filename, int flags) {
return android_dlopen_ext(filename, flags, NULL);
void* caller_addr = __builtin_return_address(0);
return dlopen_ext(filename, flags, NULL, caller_addr);
}
void* dlsym(void* handle, const char* symbol) {
@@ -97,8 +103,8 @@ void* dlsym(void* handle, const char* symbol) {
if (handle == RTLD_DEFAULT) {
sym = dlsym_linear_lookup(symbol, &found, NULL);
} else if (handle == RTLD_NEXT) {
void* ret_addr = __builtin_return_address(0);
soinfo* si = find_containing_library(ret_addr);
void* caller_addr = __builtin_return_address(0);
soinfo* si = find_containing_library(caller_addr);
sym = NULL;
if (si && si->next) {
@@ -151,7 +157,9 @@ int dladdr(const void* addr, Dl_info* info) {
int dlclose(void* handle) {
ScopedPthreadMutexLocker locker(&g_dl_mutex);
return do_dlclose(reinterpret_cast<soinfo*>(handle));
do_dlclose(reinterpret_cast<soinfo*>(handle));
// dlclose has no defined errors.
return 0;
}
// name_offset: starting index of the name in libdl_info.strtab

65
linker/linker.cpp
View File

@@ -682,7 +682,7 @@ static int open_library(const char* name) {
return fd;
}
static soinfo* load_library(const char* name, const android_dlextinfo* extinfo) {
static soinfo* load_library(const char* name, int dlflags, const android_dlextinfo* extinfo) {
// Open the file.
int fd = open_library(name);
if (fd == -1) {
@@ -710,6 +710,10 @@ static soinfo* load_library(const char* name, const android_dlextinfo* extinfo)
}
}
if ((dlflags & RTLD_NOLOAD) != 0) {
return NULL;
}
// Read the ELF header and load the segments.
if (!elf_reader.Load(extinfo)) {
return NULL;
@@ -748,33 +752,37 @@ static soinfo *find_loaded_library_by_name(const char* name) {
return NULL;
}
static soinfo* find_library_internal(const char* name, const android_dlextinfo* extinfo) {
static soinfo* find_library_internal(const char* name, int dlflags, const android_dlextinfo* extinfo) {
if (name == NULL) {
return somain;
}
soinfo* si = find_loaded_library_by_name(name);
if (si != NULL) {
if (si->flags & FLAG_LINKED) {
return si;
}
DL_ERR("OOPS: recursive link to \"%s\"", si->name);
// Library might still be loaded, the accurate detection
// of this fact is done by load_library
if (si == NULL) {
TRACE("[ '%s' has not been found by name. Trying harder...]", name);
si = load_library(name, dlflags, extinfo);
}
if (si != NULL && (si->flags & FLAG_LINKED) == 0) {
DL_ERR("recursive link to \"%s\"", si->name);
return NULL;
}
TRACE("[ '%s' has not been loaded yet. Locating...]", name);
return load_library(name, extinfo);
return si;
}
static soinfo* find_library(const char* name, const android_dlextinfo* extinfo) {
soinfo* si = find_library_internal(name, extinfo);
static soinfo* find_library(const char* name, int dlflags, const android_dlextinfo* extinfo) {
soinfo* si = find_library_internal(name, dlflags, extinfo);
if (si != NULL) {
si->ref_count++;
}
return si;
}
static int soinfo_unload(soinfo* si) {
static void soinfo_unload(soinfo* si) {
if (si->ref_count == 1) {
TRACE("unloading '%s'", si->name);
si->CallDestructors();
@@ -789,7 +797,14 @@ static int soinfo_unload(soinfo* si) {
if (d->d_tag == DT_NEEDED) {
const char* library_name = si->strtab + d->d_un.d_val;
TRACE("%s needs to unload %s", si->name, library_name);
soinfo_unload(find_loaded_library_by_name(library_name));
soinfo* needed = find_library(library_name, RTLD_NOLOAD, NULL);
if (needed != NULL) {
soinfo_unload(needed);
} else {
// Not found: for example if symlink was deleted between dlopen and dlclose
// Since we cannot really handle errors at this point - print and continue.
PRINT("warning: couldn't find %s needed by %s on unload.", library_name, si->name);
}
}
}
}
@@ -801,7 +816,6 @@ static int soinfo_unload(soinfo* si) {
si->ref_count--;
TRACE("not unloading '%s', decrementing ref_count to %zd", si->name, si->ref_count);
}
return 0;
}
void do_android_get_LD_LIBRARY_PATH(char* buffer, size_t buffer_size) {
@@ -814,8 +828,8 @@ void do_android_update_LD_LIBRARY_PATH(const char* ld_library_path) {
}
}
soinfo* do_dlopen(const char* name, int flags, const android_dlextinfo* extinfo) {
if ((flags & ~(RTLD_NOW|RTLD_LAZY|RTLD_LOCAL|RTLD_GLOBAL)) != 0) {
soinfo* do_dlopen(const char* name, int flags, soinfo* caller, const android_dlextinfo* extinfo) {
if ((flags & ~(RTLD_NOW|RTLD_LAZY|RTLD_LOCAL|RTLD_GLOBAL|RTLD_NOLOAD)) != 0) {
DL_ERR("invalid flags to dlopen: %x", flags);
return NULL;
}
@@ -824,20 +838,21 @@ soinfo* do_dlopen(const char* name, int flags, const android_dlextinfo* extinfo)
return NULL;
}
protect_data(PROT_READ | PROT_WRITE);
soinfo* si = find_library(name, extinfo);
soinfo* si = find_library(name, flags, extinfo);
if (si != NULL) {
si->CallConstructors();
somain->add_child(si);
if (caller != NULL) {
caller->add_child(si);
}
}
protect_data(PROT_READ);
return si;
}
int do_dlclose(soinfo* si) {
void do_dlclose(soinfo* si) {
protect_data(PROT_READ | PROT_WRITE);
int result = soinfo_unload(si);
soinfo_unload(si);
protect_data(PROT_READ);
return result;
}
#if defined(USE_RELA)
@@ -1435,6 +1450,10 @@ void soinfo::CallDestructors() {
// DT_FINI should be called after DT_FINI_ARRAY if both are present.
CallFunction("DT_FINI", fini_func);
// This is needed on second call to dlopen
// after library has been unloaded with RTLD_NODELETE
constructors_called = false;
}
void soinfo::add_child(soinfo* child) {
@@ -1811,7 +1830,7 @@ static bool soinfo_link_image(soinfo* si, const android_dlextinfo* extinfo) {
memset(g_ld_preloads, 0, sizeof(g_ld_preloads));
size_t preload_count = 0;
for (size_t i = 0; g_ld_preload_names[i] != NULL; i++) {
soinfo* lsi = find_library(g_ld_preload_names[i], NULL);
soinfo* lsi = find_library(g_ld_preload_names[i], 0, NULL);
if (lsi != NULL) {
g_ld_preloads[preload_count++] = lsi;
} else {
@@ -1829,7 +1848,7 @@ static bool soinfo_link_image(soinfo* si, const android_dlextinfo* extinfo) {
if (d->d_tag == DT_NEEDED) {
const char* library_name = si->strtab + d->d_un.d_val;
DEBUG("%s needs %s", si->name, library_name);
soinfo* lsi = find_library(library_name, NULL);
soinfo* lsi = find_library(library_name, 0, NULL);
if (lsi == NULL) {
strlcpy(tmp_err_buf, linker_get_error_buffer(), sizeof(tmp_err_buf));
DL_ERR("could not load library \"%s\" needed by \"%s\"; caused by %s",

4
linker/linker.h
View File

@@ -231,8 +231,8 @@ extern soinfo* get_libdl_info();
void do_android_get_LD_LIBRARY_PATH(char*, size_t);
void do_android_update_LD_LIBRARY_PATH(const char* ld_library_path);
soinfo* do_dlopen(const char* name, int flags, const android_dlextinfo* extinfo);
int do_dlclose(soinfo* si);
soinfo* do_dlopen(const char* name, int flags, soinfo* caller, const android_dlextinfo* extinfo);
void do_dlclose(soinfo* si);
ElfW(Sym)* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* start);
soinfo* find_containing_library(const void* addr);