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Add android_dlopen_ext() interface to linker.

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Add a function "android_dlopen_ext()", defined in <android/dlext.h>.
This is an extended version of dlopen() which takes a struct for passing
additional parameters for Android-specific functionality. This will be
used to support RELRO section sharing between separate processes.

Bug: 13005501
Change-Id: I9c99b2f2a02ee329dedaeba09ef3a1113b17b2d6
This commit is contained in:
Torne (Richard Coles)
2014-02-06 14:34:21 +00:00
parent 26c2bb84dd
commit 012cb4583a
5 changed files with 70 additions and 16 deletions
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29
linker/dlfcn.cpp
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@@ -20,6 +20,7 @@
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <android/dlext.h>
#include <bionic/pthread_internal.h>
#include "private/bionic_tls.h"
@@ -64,9 +65,10 @@ void android_update_LD_LIBRARY_PATH(const char* ld_library_path) {
do_android_update_LD_LIBRARY_PATH(ld_library_path);
}
void* dlopen(const char* filename, int flags) {
void* android_dlopen_ext(const char* filename, int flags, const android_dlextinfo* extinfo)
{
ScopedPthreadMutexLocker locker(&gDlMutex);
soinfo* result = do_dlopen(filename, flags);
soinfo* result = do_dlopen(filename, flags, extinfo);
if (result == NULL) {
__bionic_format_dlerror("dlopen failed", linker_get_error_buffer());
return NULL;
@@ -74,6 +76,10 @@ void* dlopen(const char* filename, int flags) {
return result;
}
void* dlopen(const char* filename, int flags) {
return android_dlopen_ext(filename, flags, NULL);
}
void* dlsym(void* handle, const char* symbol) {
ScopedPthreadMutexLocker locker(&gDlMutex);
@@ -168,15 +174,15 @@ int dlclose(void* handle) {
}
#if defined(__arm__)
// 0000000 00011111 111112 22222222 2333333 3333444444444455555555556666666 6667777777777888888888899999 9999900000000001 1
// 0123456 78901234 567890 12345678 9012345 6789012345678901234567890123456 7890123456789012345678901234 5678901234567890 1
// 0000000 00011111 111112 22222222 2333333 3333444444444455555555556666666 6667777777777888888888899999 9999900000000001 1111111112222222222 333333333344444444445
// 0123456 78901234 567890 12345678 9012345 6789012345678901234567890123456 7890123456789012345678901234 5678901234567890 1234567890123456789 012345678901234567890
# define ANDROID_LIBDL_STRTAB \
"dlopen\0dlclose\0dlsym\0dlerror\0dladdr\0android_update_LD_LIBRARY_PATH\0android_get_LD_LIBRARY_PATH\0dl_iterate_phdr\0dl_unwind_find_exidx\0"
"dlopen\0dlclose\0dlsym\0dlerror\0dladdr\0android_update_LD_LIBRARY_PATH\0android_get_LD_LIBRARY_PATH\0dl_iterate_phdr\0android_dlopen_ext\0dl_unwind_find_exidx\0"
#elif defined(__aarch64__) || defined(__i386__) || defined(__mips__) || defined(__x86_64__)
// 0000000 00011111 111112 22222222 2333333 3333444444444455555555556666666 6667777777777888888888899999 9999900000000001 1
// 0123456 78901234 567890 12345678 9012345 6789012345678901234567890123456 7890123456789012345678901234 5678901234567890 1
// 0000000 00011111 111112 22222222 2333333 3333444444444455555555556666666 6667777777777888888888899999 9999900000000001 1111111112222222222
// 0123456 78901234 567890 12345678 9012345 6789012345678901234567890123456 7890123456789012345678901234 5678901234567890 1234567890123456789
# define ANDROID_LIBDL_STRTAB \
"dlopen\0dlclose\0dlsym\0dlerror\0dladdr\0android_update_LD_LIBRARY_PATH\0android_get_LD_LIBRARY_PATH\0dl_iterate_phdr\0"
"dlopen\0dlclose\0dlsym\0dlerror\0dladdr\0android_update_LD_LIBRARY_PATH\0android_get_LD_LIBRARY_PATH\0dl_iterate_phdr\0android_dlopen_ext\0"
#else
# error Unsupported architecture. Only arm, arm64, mips, mips64, x86 and x86_64 are presently supported.
#endif
@@ -195,8 +201,9 @@ static ElfW(Sym) gLibDlSymtab[] = {
ELFW(SYM_INITIALIZER)( 36, &android_update_LD_LIBRARY_PATH, 1),
ELFW(SYM_INITIALIZER)( 67, &android_get_LD_LIBRARY_PATH, 1),
ELFW(SYM_INITIALIZER)( 95, &dl_iterate_phdr, 1),
ELFW(SYM_INITIALIZER)(111, &android_dlopen_ext, 1),
#if defined(__arm__)
ELFW(SYM_INITIALIZER)(111, &dl_unwind_find_exidx, 1),
ELFW(SYM_INITIALIZER)(130, &dl_unwind_find_exidx, 1),
#endif
};
@@ -213,9 +220,9 @@ static ElfW(Sym) gLibDlSymtab[] = {
// Note that adding any new symbols here requires stubbing them out in libdl.
static unsigned gLibDlBuckets[1] = { 1 };
#if defined(__arm__)
static unsigned gLibDlChains[] = { 0, 2, 3, 4, 5, 6, 7, 8, 9, 0 };
static unsigned gLibDlChains[] = { 0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 0 };
#else
static unsigned gLibDlChains[] = { 0, 2, 3, 4, 5, 6, 7, 8, 0 };
static unsigned gLibDlChains[] = { 0, 2, 3, 4, 5, 6, 7, 8, 9, 0 };
#endif
// This is used by the dynamic linker. Every process gets these symbols for free.