ladybird/Userland/DynamicLoader/main.cpp
Linus Groh 6e19ab2bbc AK+Everywhere: Rename String to DeprecatedString
We have a new, improved string type coming up in AK (OOM aware, no null
state), and while it's going to use UTF-8, the name UTF8String is a
mouthful - so let's free up the String name by renaming the existing
class.
Making the old one have an annoying name will hopefully also help with
quick adoption :^)
2022-12-06 08:54:33 +01:00

116 lines
3.3 KiB
C++

/*
* Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibC/sys/internals.h>
#include <LibC/unistd.h>
#include <LibELF/AuxiliaryVector.h>
#include <LibELF/DynamicLinker.h>
#include <LibELF/Relocation.h>
char* __static_environ[] = { nullptr }; // We don't get the environment without some libc workarounds..
static void init_libc()
{
environ = __static_environ;
__environ_is_malloced = false;
__stdio_is_initialized = false;
// Initialise the copy of libc included statically in Loader.so,
// initialisation of the dynamic libc.so is done by the DynamicLinker
__libc_init();
}
static void perform_self_relocations(auxv_t* auxvp)
{
// We need to relocate ourselves.
// (these relocations seem to be generated because of our vtables)
FlatPtr base_address = 0;
bool found_base_address = false;
for (; auxvp->a_type != AT_NULL; ++auxvp) {
if (auxvp->a_type == ELF::AuxiliaryValue::BaseAddress) {
base_address = auxvp->a_un.a_val;
found_base_address = true;
}
}
VERIFY(found_base_address);
if (!ELF::perform_relative_relocations(base_address))
exit(1);
}
static void display_help()
{
char const message[] =
R"(You have invoked `Loader.so'. This is the helper program for programs that
use shared libraries. Special directives embedded in executables tell the
kernel to load this program.
This helper program loads the shared libraries needed by the program,
prepares the program to run, and runs it. You do not need to invoke
this helper program directly.
)";
fprintf(stderr, "%s", message);
}
extern "C" {
// The compiler expects a previous declaration
void _start(int, char**, char**) __attribute__((used));
void _entry(int, char**, char**) __attribute__((used));
NAKED void _start(int, char**, char**)
{
#ifdef AK_ARCH_AARCH64
asm(
"bl _entry\n");
#else
asm(
"push $0\n"
"jmp _entry@plt\n");
#endif
}
void _entry(int argc, char** argv, char** envp)
{
char** env;
for (env = envp; *env; ++env) {
}
auxv_t* auxvp = (auxv_t*)++env;
perform_self_relocations(auxvp);
init_libc();
int main_program_fd = -1;
DeprecatedString main_program_path;
bool is_secure = false;
for (; auxvp->a_type != AT_NULL; ++auxvp) {
if (auxvp->a_type == ELF::AuxiliaryValue::ExecFileDescriptor) {
main_program_fd = auxvp->a_un.a_val;
}
if (auxvp->a_type == ELF::AuxiliaryValue::ExecFilename) {
main_program_path = (char const*)auxvp->a_un.a_ptr;
}
if (auxvp->a_type == ELF::AuxiliaryValue::Secure) {
is_secure = auxvp->a_un.a_val == 1;
}
}
if (main_program_path == "/usr/lib/Loader.so"sv) {
// We've been invoked directly as an executable rather than as the
// ELF interpreter for some other binary. In the future we may want
// to support launching a program directly from the dynamic loader
// like ld.so on Linux.
display_help();
_exit(1);
}
VERIFY(main_program_fd >= 0);
VERIFY(!main_program_path.is_empty());
ELF::DynamicLinker::linker_main(move(main_program_path), main_program_fd, is_secure, argc, argv, envp);
VERIFY_NOT_REACHED();
}
}