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/*
* Copyright (C) 2008 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef _LINKER_H_
#define _LINKER_H_
#include <elf.h>
#include <inttypes.h>
#include <link.h>
#include <unistd.h>
#include <android/dlext.h>
#include <sys/stat.h>
#include "private/libc_logging.h"
#include "linked_list.h"
#define DL_ERR(fmt, x...) \
do { \
__libc_format_buffer(linker_get_error_buffer(), linker_get_error_buffer_size(), fmt, ##x); \
/* If LD_DEBUG is set high enough, log every dlerror(3) message. */ \
DEBUG("%s\n", linker_get_error_buffer()); \
} while (false)
#define DL_WARN(fmt, x...) \
do { \
__libc_format_log(ANDROID_LOG_WARN, "linker", fmt, ##x); \
__libc_format_fd(2, "WARNING: linker: "); \
__libc_format_fd(2, fmt, ##x); \
__libc_format_fd(2, "\n"); \
} while (false)
#if defined(__LP64__)
#define ELFW(what) ELF64_ ## what
#else
#define ELFW(what) ELF32_ ## what
#endif
// mips64 interprets Elf64_Rel structures' r_info field differently.
// bionic (like other C libraries) has macros that assume regular ELF files,
// but the dynamic linker needs to be able to load mips64 ELF files.
#if defined(__mips__) && defined(__LP64__)
#undef ELF64_R_SYM
#undef ELF64_R_TYPE
#undef ELF64_R_INFO
#define ELF64_R_SYM(info) (((info) >> 0) & 0xffffffff)
#define ELF64_R_SSYM(info) (((info) >> 32) & 0xff)
#define ELF64_R_TYPE3(info) (((info) >> 40) & 0xff)
#define ELF64_R_TYPE2(info) (((info) >> 48) & 0xff)
#define ELF64_R_TYPE(info) (((info) >> 56) & 0xff)
#endif
// Returns the address of the page containing address 'x'.
#define PAGE_START(x) ((x) & PAGE_MASK)
// Returns the offset of address 'x' in its page.
#define PAGE_OFFSET(x) ((x) & ~PAGE_MASK)
// Returns the address of the next page after address 'x', unless 'x' is
// itself at the start of a page.
#define PAGE_END(x) PAGE_START((x) + (PAGE_SIZE-1))
#define FLAG_LINKED 0x00000001
#define FLAG_EXE 0x00000004 // The main executable
#define FLAG_LINKER 0x00000010 // The linker itself
#define FLAG_NEW_SOINFO 0x40000000 // new soinfo format
#define SOINFO_VERSION 0
#define SOINFO_NAME_LEN 128
typedef void (*linker_function_t)();
// Android uses RELA for aarch64 and x86_64. mips64 still uses REL.
#if defined(__aarch64__) || defined(__x86_64__)
#define USE_RELA 1
#endif
struct soinfo;
class SoinfoListAllocator {
public:
static LinkedListEntry<soinfo>* alloc();
static void free(LinkedListEntry<soinfo>* entry);
private:
// unconstructable
DISALLOW_IMPLICIT_CONSTRUCTORS(SoinfoListAllocator);
};
struct soinfo {
public:
typedef LinkedList<soinfo, SoinfoListAllocator> soinfo_list_t;
public:
char name[SOINFO_NAME_LEN];
const ElfW(Phdr)* phdr;
size_t phnum;
ElfW(Addr) entry;
ElfW(Addr) base;
size_t size;
#ifndef __LP64__
uint32_t unused1; // DO NOT USE, maintained for compatibility.
#endif
ElfW(Dyn)* dynamic;
#ifndef __LP64__
uint32_t unused2; // DO NOT USE, maintained for compatibility
uint32_t unused3; // DO NOT USE, maintained for compatibility
#endif
soinfo* next;
unsigned flags;
const char* strtab;
ElfW(Sym)* symtab;
size_t nbucket;
size_t nchain;
unsigned* bucket;
unsigned* chain;
#if defined(__mips__) || !defined(__LP64__)
// This is only used by mips and mips64, but needs to be here for
// all 32-bit architectures to preserve binary compatibility.
ElfW(Addr)** plt_got;
#endif
#if defined(USE_RELA)
ElfW(Rela)* plt_rela;
size_t plt_rela_count;
ElfW(Rela)* rela;
size_t rela_count;
#else
ElfW(Rel)* plt_rel;
size_t plt_rel_count;
ElfW(Rel)* rel;
size_t rel_count;
#endif
linker_function_t* preinit_array;
size_t preinit_array_count;
linker_function_t* init_array;
size_t init_array_count;
linker_function_t* fini_array;
size_t fini_array_count;
linker_function_t init_func;
linker_function_t fini_func;
#if defined(__arm__)
// ARM EABI section used for stack unwinding.
unsigned* ARM_exidx;
size_t ARM_exidx_count;
#elif defined(__mips__)
unsigned mips_symtabno;
unsigned mips_local_gotno;
unsigned mips_gotsym;
#endif
size_t ref_count;
link_map link_map_head;
bool constructors_called;
// When you read a virtual address from the ELF file, add this
// value to get the corresponding address in the process' address space.
ElfW(Addr) load_bias;
#if !defined(__LP64__)
bool has_text_relocations;
#endif
// TODO: remove this flag, dynamic linker
// should not use it in any way.
bool has_DT_SYMBOLIC;
soinfo(const char* name, const struct stat* file_stat);
void CallConstructors();
void CallDestructors();
void CallPreInitConstructors();
bool PrelinkImage();
bool LinkImage(const android_dlextinfo* extinfo);
void add_child(soinfo* child);
void remove_all_links();
void set_st_dev(dev_t st_dev);
void set_st_ino(ino_t st_ino);
ino_t get_st_ino();
dev_t get_st_dev();
soinfo_list_t& get_children();
soinfo_list_t& get_parents();
ElfW(Addr) resolve_symbol_address(ElfW(Sym)* s);
bool inline has_min_version(uint32_t min_version) {
return (flags & FLAG_NEW_SOINFO) != 0 && version >= min_version;
}
private:
void CallArray(const char* array_name, linker_function_t* functions, size_t count, bool reverse);
void CallFunction(const char* function_name, linker_function_t function);
#if defined(USE_RELA)
int Relocate(ElfW(Rela)* rela, unsigned count);
#else
int Relocate(ElfW(Rel)* rel, unsigned count);
#endif
private:
// This part of the structure is only available
// when FLAG_NEW_SOINFO is set in this->flags.
uint32_t version;
// version >= 0
dev_t st_dev;
ino_t st_ino;
// dependency graph
soinfo_list_t children;
soinfo_list_t parents;
// version >= 1
};
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);
void do_dlclose(soinfo* si);
ElfW(Sym)* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* start);
soinfo* find_containing_library(const void* addr);
ElfW(Sym)* dladdr_find_symbol(soinfo* si, const void* addr);
ElfW(Sym)* dlsym_handle_lookup(soinfo* si, soinfo** found, const char* name);
void debuggerd_init();
extern "C" abort_msg_t* g_abort_message;
extern "C" void notify_gdb_of_libraries();
char* linker_get_error_buffer();
size_t linker_get_error_buffer_size();
#endif