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cosmopolitan/tool/build/elf2pe.c
Justine Tunney ec480f5aa0
Make improvements 
- Every unit test now passes on Apple Silicon. The final piece of this
  puzzle was porting our POSIX threads cancelation support, since that
  works differently on ARM64 XNU vs. AMD64. Our semaphore support on
  Apple Silicon is also superior now compared to AMD64, thanks to the
  grand central dispatch library which lets *NSYNC locks go faster.

- The Cosmopolitan runtime is now more stable, particularly on Windows.
  To do this, thread local storage is mandatory at all runtime levels,
  and the innermost packages of the C library is no longer being built
  using ASAN. TLS is being bootstrapped with a 128-byte TIB during the
  process startup phase, and then later on the runtime re-allocates it
  either statically or dynamically to support code using _Thread_local.
  fork() and execve() now do a better job cooperating with threads. We
  can now check how much stack memory is left in the process or thread
  when functions like kprintf() / execve() etc. call alloca(), so that
  ENOMEM can be raised, reduce a buffer size, or just print a warning.

- POSIX signal emulation is now implemented the same way kernels do it
  with pthread_kill() and raise(). Any thread can interrupt any other
  thread, regardless of what it's doing. If it's blocked on read/write
  then the killer thread will cancel its i/o operation so that EINTR can
  be returned in the mark thread immediately. If it's doing a tight CPU
  bound operation, then that's also interrupted by the signal delivery.
  Signal delivery works now by suspending a thread and pushing context
  data structures onto its stack, and redirecting its execution to a
  trampoline function, which calls SetThreadContext(GetCurrentThread())
  when it's done.

- We're now doing a better job managing locks and handles. On NetBSD we
  now close semaphore file descriptors in forked children. Semaphores on
  Windows can now be canceled immediately, which means mutexes/condition
  variables will now go faster. Apple Silicon semaphores can be canceled
  too. We're now using Apple's pthread_yield() funciton. Apple _nocancel
  syscalls are now used on XNU when appropriate to ensure pthread_cancel
  requests aren't lost. The MbedTLS library has been updated to support
  POSIX thread cancelations. See tool/build/runitd.c for an example of
  how it can be used for production multi-threaded tls servers. Handles
  on Windows now leak less often across processes. All i/o operations on
  Windows are now overlapped, which means file pointers can no longer be
  inherited across dup() and fork() for the time being.

- We now spawn a thread on Windows to deliver SIGCHLD and wakeup wait4()
  which means, for example, that posix_spawn() now goes 3x faster. POSIX
  spawn is also now more correct. Like Musl, it's now able to report the
  failure code of execve() via a pipe although our approach favors using
  shared memory to do that on systems that have a true vfork() function.

- We now spawn a thread to deliver SIGALRM to threads when setitimer()
  is used. This enables the most precise wakeups the OS makes possible.

- The Cosmopolitan runtime now uses less memory. On NetBSD for example,
  it turned out the kernel would actually commit the PT_GNU_STACK size
  which caused RSS to be 6mb for every process. Now it's down to ~4kb.
  On Apple Silicon, we reduce the mandatory upstream thread size to the
  smallest possible size to reduce the memory overhead of Cosmo threads.
  The examples directory has a program called greenbean which can spawn
  a web server on Linux with 10,000 worker threads and have the memory
  usage of the process be ~77mb. The 1024 byte overhead of POSIX-style
  thread-local storage is now optional; it won't be allocated until the
  pthread_setspecific/getspecific functions are called. On Windows, the
  threads that get spawned which are internal to the libc implementation
  use reserve rather than commit memory, which shaves a few hundred kb.

- sigaltstack() is now supported on Windows, however it's currently not
  able to be used to handle stack overflows, since crash signals are
  still generated by WIN32. However the crash handler will still switch
  to the alt stack, which is helpful in environments with tiny threads.

- Test binaries are now smaller. Many of the mandatory dependencies of
  the test runner have been removed. This ensures many programs can do a
  better job only linking the the thing they're testing. This caused the
  test binaries for LIBC_FMT for example, to decrease from 200kb to 50kb

- long double is no longer used in the implementation details of libc,
  except in the APIs that define it. The old code that used long double
  for time (instead of struct timespec) has now been thoroughly removed.

- ShowCrashReports() is now much tinier in MODE=tiny. Instead of doing
  backtraces itself, it'll just print a command you can run on the shell
  using our new `cosmoaddr2line` program to view the backtrace.

- Crash report signal handling now works in a much better way. Instead
  of terminating the process, it now relies on SA_RESETHAND so that the
  default SIG_IGN behavior can terminate the process if necessary.

- Our pledge() functionality has now been fully ported to AARCH64 Linux.
2023-09-18 21:04:47 -07:00

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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2023 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/calls/calls.h"
#include "libc/elf/def.h"
#include "libc/elf/elf.h"
#include "libc/elf/scalar.h"
#include "libc/elf/struct/rela.h"
#include "libc/elf/struct/shdr.h"
#include "libc/fmt/conv.h"
#include "libc/fmt/itoa.h"
#include "libc/intrin/bits.h"
#include "libc/intrin/describeflags.internal.h"
#include "libc/intrin/dll.h"
#include "libc/limits.h"
#include "libc/macros.internal.h"
#include "libc/mem/mem.h"
#include "libc/nt/pedef.internal.h"
#include "libc/nt/struct/imagedatadirectory.internal.h"
#include "libc/nt/struct/imagedosheader.internal.h"
#include "libc/nt/struct/imagefileheader.internal.h"
#include "libc/nt/struct/imageimportdescriptor.internal.h"
#include "libc/nt/struct/imageoptionalheader.internal.h"
#include "libc/nt/struct/imagesectionheader.internal.h"
#include "libc/runtime/runtime.h"
#include "libc/stdckdint.h"
#include "libc/stdio/stdio.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/map.h"
#include "libc/sysv/consts/o.h"
#include "libc/sysv/consts/prot.h"
#include "third_party/getopt/getopt.internal.h"
// see tool/hello/hello-pe.c for an example program this can link
// make -j8 m=tiny o/tiny/tool/hello/hello-pe.com
#pragma GCC diagnostic ignored "-Wstringop-overflow"
#define VERSION \
"elf2pe v0.1\n" \
"copyright 2023 justine tunney\n" \
"https://github.com/jart/cosmopolitan\n"
#define MANUAL \
" -o OUTPUT INPUT\n" \
"\n" \
"DESCRIPTION\n" \
"\n" \
" Converts ELF executables to PE\n" \
"\n" \
"FLAGS\n" \
"\n" \
" -h show usage\n" \
" -o OUTPUT set output path\n" \
" -D PATH embed dos/bios stub\n" \
" -S SIZE size of stack commit\n" \
" -R SIZE size of stack reserve\n" \
"\n"
#define MAX_ALIGN 65536
#define ALIGN_VIRT(p, a) ROUNDUP(p, (long)(a))
#define ALIGN_FILE(p, a) (char *)ROUNDUP((uintptr_t)(p), (long)(a))
#define FUNC_CONTAINER(e) DLL_CONTAINER(struct Func, elem, e)
#define LIBRARY_CONTAINER(e) DLL_CONTAINER(struct Library, elem, e)
#define SECTION_CONTAINER(e) DLL_CONTAINER(struct Section, elem, e)
#define SEGMENT_CONTAINER(e) DLL_CONTAINER(struct Segment, elem, e)
struct ImagePointer {
char *fp;
int64_t vp;
};
struct Func {
const char *name;
struct Dll elem;
uint64_t *ilt;
Elf64_Sym *symbol;
};
struct Library {
const char *name;
struct Dll *funcs;
struct Dll elem;
struct NtImageImportDescriptor *idt;
uint64_t *ilt;
size_t iltbytes;
};
struct Section {
int prot;
int index;
char *name;
Elf64_Shdr *shdr;
Elf64_Rela *relas;
Elf64_Xword relacount;
struct Dll elem;
};
struct Segment {
int prot;
char *ptr_new;
bool hasnobits;
bool hasprogbits;
Elf64_Xword align;
Elf64_Off offset_min;
Elf64_Off offset_max;
Elf64_Addr vaddr_min;
Elf64_Addr vaddr_max;
Elf64_Addr vaddr_new_min;
Elf64_Addr vaddr_new_max;
struct Dll *sections;
struct Dll elem;
struct NtImageSectionHeader *pesection;
};
struct Elf {
union {
char *map;
Elf64_Ehdr *ehdr;
};
size_t size;
const char *path;
char *strtab;
char *secstrs;
Elf64_Sym *symtab;
Elf64_Shdr *symhdr;
Elf64_Xword align;
Elf64_Xword symcount;
struct Dll *imports;
struct Dll *segments;
Elf64_Half text_count;
Elf64_Half rdata_count;
Elf64_Half data_count;
Elf64_Half bss_count;
};
static const char *prog;
static const char *outpath;
static const char *stubpath;
static long FLAG_SizeOfStackCommit = 64 * 1024;
static long FLAG_SizeOfStackReserve = 8 * 1024 * 1024;
static wontreturn void Die(const char *thing, const char *reason) {
tinyprint(2, thing, ": ", reason, "\n", NULL);
exit(1);
}
static wontreturn void DieSys(const char *thing) {
perror(thing);
exit(1);
}
static wontreturn void ShowUsage(int rc, int fd) {
tinyprint(fd, VERSION, "\nUSAGE\n\n ", prog, MANUAL, NULL);
exit(rc);
}
static wontreturn void DieOom(void) {
Die("makepe", "out of memory");
}
static void *Calloc(size_t n) {
void *p;
if (!(p = calloc(1, n))) DieOom();
return p;
}
static void *Realloc(void *p, size_t n) {
if (!(p = realloc(p, n))) DieOom();
return p;
}
static struct Func *NewFunc(void) {
struct Func *s;
s = Calloc(sizeof(struct Func));
dll_init(&s->elem);
return s;
}
static struct Library *NewLibrary(void) {
struct Library *s;
s = Calloc(sizeof(struct Library));
dll_init(&s->elem);
return s;
}
static struct Section *NewSection(void) {
struct Section *s;
s = Calloc(sizeof(struct Section));
dll_init(&s->elem);
return s;
}
static struct Segment *NewSegment(void) {
struct Segment *s;
s = Calloc(sizeof(struct Segment));
dll_init(&s->elem);
return s;
}
static Elf64_Addr RelocateVaddrWithinSegment(struct Elf *elf,
Elf64_Addr vaddr_old,
struct Segment *segment) {
unassert(segment->vaddr_min <= vaddr_old && vaddr_old < segment->vaddr_max);
Elf64_Addr vaddr_new =
vaddr_old + (segment->vaddr_new_min - segment->vaddr_min);
unassert(segment->vaddr_new_min <= vaddr_new &&
vaddr_new < segment->vaddr_new_max);
return vaddr_new;
}
static Elf64_Addr RelocateVaddr(struct Elf *elf, Elf64_Addr vaddr) {
for (struct Dll *e = dll_first(elf->segments); e;
e = dll_next(elf->segments, e)) {
struct Segment *segment = SEGMENT_CONTAINER(e);
if (segment->vaddr_min <= vaddr && vaddr < segment->vaddr_max) {
return RelocateVaddrWithinSegment(elf, vaddr, segment);
}
}
return -1;
}
static Elf64_Phdr *GetTlsPhdr(struct Elf *elf) {
Elf64_Phdr *phdr;
for (int i = 0; i < elf->ehdr->e_phnum; ++i) {
if ((phdr = GetElfProgramHeaderAddress(elf->ehdr, elf->size, i)) &&
phdr->p_type == PT_TLS) {
return phdr;
}
}
Die(elf->path, "ELF has TLS relocations but no PT_TLS program header");
}
static Elf64_Addr RelocateTlsVaddr(struct Elf *elf, Elf64_Addr vaddr) {
Elf64_Addr res;
if ((res = RelocateVaddr(elf, vaddr)) != -1) {
return res;
} else {
Die(elf->path, "ELF PT_TLS program header doesn't overlap with any of "
"the loaded segments we're copying");
}
}
static Elf64_Addr GetTpAddr(struct Elf *elf) {
unassert(elf->ehdr->e_machine == EM_NEXGEN32E ||
elf->ehdr->e_machine == EM_S390);
Elf64_Phdr *p = GetTlsPhdr(elf);
return RelocateTlsVaddr(
elf, (p->p_vaddr + p->p_memsz + (p->p_align - 1)) & -p->p_align);
}
static Elf64_Addr GetDtpAddr(struct Elf *elf) {
unassert(elf->ehdr->e_machine != EM_PPC64 &&
elf->ehdr->e_machine != EM_RISCV);
Elf64_Phdr *p = GetTlsPhdr(elf);
return RelocateTlsVaddr(elf, p->p_vaddr);
}
static void RelocateRela(struct Elf *elf, struct Segment *segment,
struct Section *section, Elf64_Rela *rela) {
Elf64_Addr place_vaddr =
RelocateVaddrWithinSegment(elf, rela->r_offset, segment);
Elf64_Addr symbol_vaddr = elf->symtab[ELF64_R_SYM(rela->r_info)].st_value;
char *place_ptr = segment->ptr_new + (place_vaddr - segment->vaddr_new_min);
switch (ELF64_R_TYPE(rela->r_info)) {
case R_X86_64_NONE: // do nothing
case R_X86_64_COPY: // do nothing
case R_X86_64_SIZE32: // isn't impacted
case R_X86_64_SIZE64: // isn't impacted
break;
case R_X86_64_64: { // S + A
uint64_t abs64;
if (ckd_add(&abs64, symbol_vaddr, rela->r_addend)) {
fprintf(stderr,
"%s: ELF R_X86_64_64 relocation %lx + %ld overflowed "
"at %lx in section %s\n",
elf->path, symbol_vaddr, rela->r_addend, place_vaddr,
section->name);
exit(1);
}
memcpy(place_ptr, &abs64, sizeof(abs64));
break;
}
case R_X86_64_32: { // S + A
uint32_t abs32;
if (ckd_add(&abs32, symbol_vaddr, rela->r_addend)) {
fprintf(stderr,
"%s: ELF R_X86_64_32 relocation %lx + %ld overflowed "
"at %lx in section %s\n",
elf->path, symbol_vaddr, rela->r_addend, place_vaddr,
section->name);
exit(1);
}
memcpy(place_ptr, &abs32, sizeof(abs32));
break;
}
case R_X86_64_32S: { // S + A
int32_t abs32s;
if (ckd_add(&abs32s, symbol_vaddr, rela->r_addend)) {
fprintf(stderr,
"%s: ELF R_X86_64_32S relocation %lx + %ld overflowed "
"at %lx in section %s\n",
elf->path, symbol_vaddr, rela->r_addend, place_vaddr,
section->name);
exit(1);
}
memcpy(place_ptr, &abs32s, sizeof(abs32s));
break;
}
case R_X86_64_16: { // S + A
uint16_t abs16;
if (ckd_add(&abs16, symbol_vaddr, rela->r_addend)) {
fprintf(stderr,
"%s: ELF R_X86_64_16 relocation %lx + %ld overflowed "
"at %lx in section %s\n",
elf->path, symbol_vaddr, rela->r_addend, place_vaddr,
section->name);
exit(1);
}
memcpy(place_ptr, &abs16, sizeof(abs16));
break;
}
case R_X86_64_8: { // S + A
uint8_t abs8;
if (ckd_add(&abs8, symbol_vaddr, rela->r_addend)) {
fprintf(stderr,
"%s: ELF R_X86_64_8 relocation %lx + %ld overflowed "
"at %lx in section %s\n",
elf->path, symbol_vaddr, rela->r_addend, place_vaddr,
section->name);
exit(1);
}
memcpy(place_ptr, &abs8, sizeof(abs8));
break;
}
case R_X86_64_PC64: { // S + A - P
int64_t pc64;
Elf64_Sxword tmp;
if (ckd_add(&tmp, symbol_vaddr, rela->r_addend) ||
ckd_sub(&pc64, tmp, place_vaddr)) {
fprintf(stderr,
"%s: ELF R_X86_64_PC64 relocation %lx + %ld - %lx overflowed "
"at %lx in section %s\n",
elf->path, symbol_vaddr, rela->r_addend, place_vaddr,
place_vaddr, section->name);
exit(1);
}
memcpy(place_ptr, &pc64, sizeof(pc64));
break;
}
case R_X86_64_PC32: // S + A - P
case R_X86_64_PLT32: {
int32_t pc32;
Elf64_Sxword tmp;
if (ckd_add(&tmp, symbol_vaddr, rela->r_addend) ||
ckd_sub(&pc32, tmp, place_vaddr)) {
fprintf(stderr,
"%s: ELF R_X86_64_PC32 relocation %lx + %ld - %lx overflowed "
"at %lx in section %s\n",
elf->path, symbol_vaddr, rela->r_addend, place_vaddr,
place_vaddr, section->name);
exit(1);
}
memcpy(place_ptr, &pc32, sizeof(pc32));
break;
}
case R_X86_64_PC16: { // S + A - P
int16_t pc16;
Elf64_Sxword tmp;
if (ckd_add(&tmp, symbol_vaddr, rela->r_addend) ||
ckd_sub(&pc16, tmp, place_vaddr)) {
fprintf(stderr,
"%s: ELF R_X86_64_PC16 relocation %lx + %ld - %lx overflowed "
"at %lx in section %s\n",
elf->path, symbol_vaddr, rela->r_addend, place_vaddr,
place_vaddr, section->name);
exit(1);
}
memcpy(place_ptr, &pc16, sizeof(pc16));
break;
}
case R_X86_64_PC8: { // S + A - P
int8_t pc8;
Elf64_Sxword tmp;
if (ckd_add(&tmp, symbol_vaddr, rela->r_addend) ||
ckd_sub(&pc8, tmp, place_vaddr)) {
fprintf(stderr,
"%s: ELF R_X86_64_PC8 relocation %lx + %ld - %lx overflowed "
"at %lx in section %s\n",
elf->path, symbol_vaddr, rela->r_addend, place_vaddr,
place_vaddr, section->name);
exit(1);
}
memcpy(place_ptr, &pc8, sizeof(pc8));
break;
}
case R_X86_64_DTPOFF32: { // S + A - T
int32_t pc32;
Elf64_Addr dtp;
Elf64_Sxword tmp;
dtp = GetDtpAddr(elf);
if (ckd_add(&tmp, symbol_vaddr, rela->r_addend) ||
ckd_sub(&pc32, tmp, dtp)) {
fprintf(
stderr,
"%s: ELF R_X86_64_DTPOFF32 relocation %lx + %ld - %lx overflowed "
"at %lx in section %s\n",
elf->path, symbol_vaddr, rela->r_addend, dtp, place_vaddr,
section->name);
exit(1);
}
memcpy(place_ptr, &pc32, sizeof(pc32));
break;
}
case R_X86_64_DTPOFF64: { // S + A - T
int64_t pc64;
Elf64_Addr dtp;
Elf64_Sxword tmp;
dtp = GetDtpAddr(elf);
if (ckd_add(&tmp, symbol_vaddr, rela->r_addend) ||
ckd_sub(&pc64, tmp, dtp)) {
fprintf(
stderr,
"%s: ELF R_X86_64_DTPOFF64 relocation %lx + %ld - %lx overflowed "
"at %lx in section %s\n",
elf->path, symbol_vaddr, rela->r_addend, dtp, place_vaddr,
section->name);
exit(1);
}
memcpy(place_ptr, &pc64, sizeof(pc64));
break;
}
case R_X86_64_TPOFF32: { // S + A - T
int32_t pc32;
Elf64_Addr tp;
Elf64_Sxword tmp;
tp = GetTpAddr(elf);
if (ckd_add(&tmp, symbol_vaddr, rela->r_addend) ||
ckd_sub(&pc32, tmp, tp)) {
fprintf(
stderr,
"%s: ELF R_X86_64_TPOFF32 relocation %lx + %ld - %lx overflowed "
"at %lx in section %s\n",
elf->path, symbol_vaddr, rela->r_addend, tp, place_vaddr,
section->name);
exit(1);
}
memcpy(place_ptr, &pc32, sizeof(pc32));
break;
}
case R_X86_64_TPOFF64: { // S + A - T
int64_t pc64;
Elf64_Addr tp;
Elf64_Sxword tmp;
tp = GetTpAddr(elf);
if (ckd_add(&tmp, symbol_vaddr, rela->r_addend) ||
ckd_sub(&pc64, tmp, tp)) {
fprintf(
stderr,
"%s: ELF R_X86_64_TPOFF64 relocation %lx + %ld - %lx overflowed "
"at %lx in section %s\n",
elf->path, symbol_vaddr, rela->r_addend, tp, place_vaddr,
section->name);
exit(1);
}
memcpy(place_ptr, &pc64, sizeof(pc64));
break;
}
default:
fprintf(stderr, "%s: don't understand ELF relocation type %d\n",
elf->path, ELF64_R_TYPE(rela->r_info));
}
}
static void RelocateSection(struct Elf *elf, struct Segment *segment,
struct Section *section) {
for (Elf64_Xword i = 0; i < section->relacount; ++i) {
RelocateRela(elf, segment, section, section->relas + i);
}
}
static void RelocateSegment(struct Elf *elf, struct Segment *segment) {
unassert(segment->ptr_new);
unassert(segment->hasprogbits);
for (struct Dll *e = dll_first(segment->sections); e;
e = dll_next(segment->sections, e)) {
struct Section *section = SECTION_CONTAINER(e);
RelocateSection(elf, segment, section);
}
}
static void RelocateElf(struct Elf *elf) {
for (Elf64_Xword i = 0; i < elf->symcount; ++i) {
if (elf->symtab[i].st_shndx != SHN_ABS &&
elf->symtab[i].st_shndx != SHN_UNDEF &&
ELF64_ST_TYPE(elf->symtab[i].st_info) != STT_TLS) {
elf->symtab[i].st_value = RelocateVaddr(elf, elf->symtab[i].st_value);
}
}
for (struct Dll *e = dll_first(elf->segments); e;
e = dll_next(elf->segments, e)) {
struct Segment *segment = SEGMENT_CONTAINER(e);
if (segment->hasprogbits) {
RelocateSegment(elf, segment);
}
}
}
static struct Elf64_Sym *FindGlobal(struct Elf *elf, const char *name) {
Elf64_Xword i;
for (i = elf->symhdr->sh_info; i < elf->symcount; ++i) {
if (elf->symtab[i].st_name &&
!strcmp(elf->strtab + elf->symtab[i].st_name, name)) {
return elf->symtab + i;
}
}
return 0;
}
static int GetRelaSectionIndex(struct Elf *elf, int i) {
int j;
Elf64_Shdr *shdr;
for (j = 0; j < elf->ehdr->e_shnum; ++j) {
if ((shdr = GetElfSectionHeaderAddress(elf->ehdr, elf->size, j)) &&
shdr->sh_type == SHT_RELA && shdr->sh_info == i) {
return j;
}
}
return -1;
}
static struct Section *LoadSection(struct Elf *elf, int index,
Elf64_Shdr *shdr) {
int rela_index;
Elf64_Shdr *rela_shdr;
struct Section *section;
section = NewSection();
section->index = index;
section->shdr = shdr;
section->prot = PROT_READ;
section->name = elf->secstrs + shdr->sh_name;
if (shdr->sh_flags & SHF_WRITE) {
section->prot |= PROT_WRITE;
}
if (shdr->sh_flags & SHF_EXECINSTR) {
section->prot |= PROT_EXEC;
}
if ((rela_index = GetRelaSectionIndex(elf, index)) != -1 &&
(rela_shdr =
GetElfSectionHeaderAddress(elf->ehdr, elf->size, rela_index)) &&
(section->relas =
GetElfSectionAddress(elf->ehdr, elf->size, rela_shdr))) {
section->relacount = rela_shdr->sh_size / sizeof(Elf64_Rela);
}
return section;
}
static void LoadSectionsIntoSegments(struct Elf *elf) {
int i;
Elf64_Shdr *shdr;
bool hasdataseg = false;
struct Segment *segment = 0;
for (i = 0; i < elf->ehdr->e_shnum; ++i) {
if ((shdr = GetElfSectionHeaderAddress(elf->ehdr, elf->size, i)) &&
(shdr->sh_type == SHT_PROGBITS || shdr->sh_type == SHT_NOBITS) &&
!((shdr->sh_flags & SHF_TLS) && shdr->sh_type == SHT_NOBITS) &&
(shdr->sh_flags & SHF_ALLOC)) {
struct Section *section;
section = LoadSection(elf, i, shdr);
if (segment && (segment->prot != section->prot ||
(segment->hasnobits && shdr->sh_type == SHT_PROGBITS))) {
dll_make_last(&elf->segments, &segment->elem);
segment = 0;
}
if (!segment) {
segment = NewSegment();
segment->prot = section->prot;
segment->vaddr_min = section->shdr->sh_addr;
if (shdr->sh_type == SHT_PROGBITS)
segment->offset_min = section->shdr->sh_offset;
hasdataseg |= segment->prot == (PROT_READ | PROT_WRITE);
}
segment->hasnobits |= shdr->sh_type == SHT_NOBITS;
segment->hasprogbits |= shdr->sh_type == SHT_PROGBITS;
segment->vaddr_max = section->shdr->sh_addr + section->shdr->sh_size;
if (shdr->sh_type == SHT_PROGBITS)
segment->offset_max = section->shdr->sh_offset + section->shdr->sh_size;
segment->align = MAX(segment->align, section->shdr->sh_addralign);
elf->align = MAX(elf->align, segment->align);
dll_make_last(&segment->sections, &section->elem);
}
}
if (segment) {
dll_make_last(&elf->segments, &segment->elem);
}
if (elf->imports && !hasdataseg) {
// if the program we're linking is really tiny and it doesn't have
// either a .data or .bss section but it does import function from
// libraries, then create a synthetic .data segment for the pe iat
segment = NewSegment();
segment->align = 8;
segment->hasprogbits = true;
segment->prot = PROT_READ | PROT_WRITE;
dll_make_last(&elf->segments, &segment->elem);
}
}
static bool ParseDllImportSymbol(const char *symbol_name,
const char **out_dll_name,
const char **out_func_name) {
size_t n;
char *dll_name;
const char *dolla;
if (!startswith(symbol_name, "dll$")) return false;
symbol_name += 4;
dolla = strchr(symbol_name, '$');
if (!dolla) return false;
n = dolla - symbol_name;
dll_name = memcpy(Calloc(n + 1), symbol_name, n);
*out_dll_name = dll_name;
*out_func_name = dolla + 1;
return true;
}
static struct Library *FindImport(struct Elf *elf, const char *name) {
struct Dll *e;
for (e = dll_first(elf->imports); e; e = dll_next(elf->imports, e)) {
struct Library *library = LIBRARY_CONTAINER(e);
if (!strcmp(name, library->name)) {
return library;
}
}
return 0;
}
static void LoadDllImports(struct Elf *elf) {
Elf64_Xword i;
struct Func *func;
const char *dll_name;
const char *func_name;
struct Library *library;
for (i = 0; i < elf->symcount; ++i) {
Elf64_Sym *symbol = elf->symtab + i;
if (symbol->st_name && ParseDllImportSymbol(elf->strtab + symbol->st_name,
&dll_name, &func_name)) {
if (symbol->st_value || symbol->st_shndx != SHN_UNDEF)
Die(elf->path, "ELF executable declared a dll: import symbol without "
"annotating it weak extern");
if (!(library = FindImport(elf, dll_name))) {
library = NewLibrary();
library->name = dll_name;
dll_make_last(&elf->imports, &library->elem);
}
func = NewFunc();
func->name = func_name;
func->symbol = symbol;
dll_make_last(&library->funcs, &func->elem);
}
}
}
static struct Elf *OpenElf(const char *path) {
int fd;
struct Elf *elf;
elf = Calloc(sizeof(*elf));
elf->path = path;
if ((fd = open(path, O_RDONLY)) == -1) DieSys(path);
if ((elf->size = lseek(fd, 0, SEEK_END)) == -1) DieSys(path);
elf->map = mmap(0, elf->size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
if (elf->map == MAP_FAILED) DieSys(path);
if (!IsElf64Binary(elf->ehdr, elf->size)) Die(path, "not an elf64 binary");
elf->symhdr =
GetElfSymbolTable(elf->ehdr, elf->size, SHT_SYMTAB, &elf->symcount);
elf->symtab = GetElfSectionAddress(elf->ehdr, elf->size, elf->symhdr);
if (!elf->symtab) Die(path, "elf doesn't have symbol table");
elf->strtab = GetElfStringTable(elf->ehdr, elf->size, ".strtab");
if (!elf->strtab) Die(path, "elf doesn't have string table");
elf->secstrs = GetElfSectionNameStringTable(elf->ehdr, elf->size);
if (!elf->strtab) Die(path, "elf doesn't have section string table");
LoadDllImports(elf);
LoadSectionsIntoSegments(elf);
close(fd);
return elf;
}
static void PrintElf(struct Elf *elf) {
struct Dll *e, *g;
printf("\n");
printf("%s\n", elf->path);
printf("sections\n");
for (e = dll_first(elf->segments); e; e = dll_next(elf->segments, e)) {
struct Segment *segment = SEGMENT_CONTAINER(e);
for (g = dll_first(segment->sections); g;
g = dll_next(segment->sections, g)) {
struct Section *section = SECTION_CONTAINER(g);
printf("\t%s\n", section->name);
}
printf("\t\talign = %ld\n", segment->align);
printf("\t\tvaddr_old = %lx\n", segment->vaddr_min);
printf("\t\tvaddr_new = %lx\n", segment->vaddr_new_min);
printf("\t\tprot = %s\n", DescribeProtFlags(segment->prot));
}
printf("imports\n");
for (e = dll_first(elf->imports); e; e = dll_next(elf->imports, e)) {
struct Library *library = LIBRARY_CONTAINER(e);
printf("\t%s\n", library->name);
for (g = dll_first(library->funcs); g; g = dll_next(library->funcs, g)) {
struct Func *func = FUNC_CONTAINER(g);
printf("\t\t%s\n", func->name);
}
}
}
static void PickPeSectionName(char *p, struct Elf *elf,
struct Segment *segment) {
int n;
switch (segment->prot) {
case PROT_EXEC:
case PROT_EXEC | PROT_READ:
case PROT_EXEC | PROT_READ | PROT_WRITE:
p = stpcpy(p, ".text");
n = ++elf->text_count;
break;
case PROT_READ:
p = stpcpy(p, ".rdata");
n = ++elf->rdata_count;
break;
case PROT_READ | PROT_WRITE:
if (segment->hasprogbits) {
p = stpcpy(p, ".data");
n = ++elf->data_count;
} else {
p = stpcpy(p, ".bss");
n = ++elf->bss_count;
}
break;
default:
notpossible;
}
if (n > 1) {
FormatInt32(p, n);
}
}
static uint32_t GetPeSectionCharacteristics(struct Segment *s) {
uint32_t x = 0;
if (s->prot & PROT_EXEC) {
x |= kNtPeSectionCntCode | kNtPeSectionMemExecute;
} else if (s->hasprogbits) {
x |= kNtPeSectionCntInitializedData;
}
if (s->prot & PROT_READ) {
x |= kNtPeSectionMemRead;
}
if (s->prot & PROT_WRITE) {
x |= kNtPeSectionMemWrite;
}
if (s->hasnobits) {
x |= kNtPeSectionCntUninitializedData;
}
return x;
}
// converts static elf executable to portable executable
//
// the trick to generating a portable executable is to maintain the file
// pointer and virtual address pointers separately, as the image is made
//
// during this process, we're going to be inserting and removing padding
// to both the file layout and virtual address space, that weren't there
// originally in the elf image that ld linked. in order for this to work
// the executable needs to be linked in `ld -q` mode, since it'll retain
// the .rela sections we'll need later to fixup the binary.
static struct ImagePointer GeneratePe(struct Elf *elf, char *fp, int64_t vp) {
Elf64_Sym *entry;
if (!(entry = FindGlobal(elf, "__win32_start")) &&
!(entry = FindGlobal(elf, "WinMain")))
Die(elf->path, "ELF didn't define global `__win32_start` PE entrypoint or "
"alternatively a `WinMain` function");
if (elf->align > MAX_ALIGN)
Die(elf->path, "ELF specified an alignment greater than 64k which isn't "
"supported by the PE format");
vp = ALIGN_VIRT(vp, 65536);
struct NtImageDosHeader *mzhdr;
mzhdr = (struct NtImageDosHeader *)fp;
fp += sizeof(struct NtImageDosHeader);
memcpy(mzhdr, "MZ", 2);
// embed the ms-dos stub and/or bios bootloader
if (stubpath) {
int fd = open(stubpath, O_RDONLY);
if (fd == -1) DieSys(stubpath);
for (;;) {
ssize_t got = read(fd, fp, 512);
if (got == -1) DieSys(stubpath);
if (!got) break;
fp += got;
}
if (close(fd)) DieSys(stubpath);
}
// output portable executable magic
fp = ALIGN_FILE(fp, 8);
mzhdr->e_lfanew = fp - (char *)mzhdr;
fp = WRITE32LE(fp, 'P' | 'E' << 8);
// output coff header
struct NtImageFileHeader *filehdr;
filehdr = (struct NtImageFileHeader *)fp;
fp += sizeof(struct NtImageFileHeader);
filehdr->Machine = kNtImageFileMachineNexgen32e;
filehdr->TimeDateStamp = 1690072024;
filehdr->Characteristics =
kNtPeFileExecutableImage | kNtImageFileLargeAddressAware |
kNtPeFileRelocsStripped | kNtPeFileLineNumsStripped |
kNtPeFileLocalSymsStripped;
// output "optional" header
struct NtImageOptionalHeader *opthdr;
opthdr = (struct NtImageOptionalHeader *)fp;
fp += sizeof(struct NtImageOptionalHeader);
opthdr->Magic = kNtPe64bit;
opthdr->MajorLinkerVersion = 14;
opthdr->MinorLinkerVersion = 35;
opthdr->ImageBase = vp;
opthdr->FileAlignment = 512;
opthdr->SectionAlignment = MAX(4096, elf->align);
opthdr->MajorOperatingSystemVersion = 6;
opthdr->MajorSubsystemVersion = 6;
opthdr->Subsystem = kNtImageSubsystemWindowsCui;
opthdr->DllCharacteristics = kNtImageDllcharacteristicsNxCompat |
kNtImageDllcharacteristicsHighEntropyVa;
opthdr->SizeOfStackReserve =
MAX(FLAG_SizeOfStackReserve, FLAG_SizeOfStackCommit);
opthdr->SizeOfStackCommit = FLAG_SizeOfStackCommit;
// output data directory entries
if (elf->imports) {
opthdr->NumberOfRvaAndSizes = 2;
fp += opthdr->NumberOfRvaAndSizes * sizeof(struct NtImageDataDirectory);
}
// finish optional header
filehdr->SizeOfOptionalHeader = fp - (char *)opthdr;
// output section headers
struct NtImageSectionHeader *sections;
sections = (struct NtImageSectionHeader *)fp;
struct NtImageSectionHeader *idata_section;
idata_section = (struct NtImageSectionHeader *)fp;
if (elf->imports) {
fp += sizeof(struct NtImageSectionHeader);
++filehdr->NumberOfSections;
}
for (struct Dll *e = dll_first(elf->segments); e;
e = dll_next(elf->segments, e)) {
struct Segment *segment = SEGMENT_CONTAINER(e);
segment->pesection = (struct NtImageSectionHeader *)fp;
fp += sizeof(struct NtImageSectionHeader);
++filehdr->NumberOfSections;
}
// finish headers
fp = ALIGN_FILE(fp, opthdr->FileAlignment);
opthdr->SizeOfHeaders = fp - (char *)mzhdr;
vp += opthdr->SizeOfHeaders;
// output .idata section
if (elf->imports) {
vp = ALIGN_VIRT(vp, opthdr->SectionAlignment);
char *fbegin = fp;
int64_t vbegin = vp;
idata_section->VirtualAddress = vp - opthdr->ImageBase;
idata_section->PointerToRawData = fbegin - (char *)mzhdr;
//////////////////////////////////////////////////////////////////////
strcpy(idata_section->Name, ".idata");
idata_section->Characteristics =
kNtPeSectionMemRead | kNtPeSectionCntInitializedData;
// output import descriptor for each dll
for (struct Dll *e = dll_first(elf->imports); e;
e = dll_next(elf->imports, e)) {
struct Library *library = LIBRARY_CONTAINER(e);
library->idt = (struct NtImageImportDescriptor *)fp;
fp += sizeof(struct NtImageImportDescriptor);
vp += sizeof(struct NtImageImportDescriptor);
}
fp += sizeof(struct NtImageImportDescriptor);
vp += sizeof(struct NtImageImportDescriptor);
opthdr->DataDirectory[kNtImageDirectoryEntryImport].VirtualAddress =
idata_section->VirtualAddress;
opthdr->DataDirectory[kNtImageDirectoryEntryImport].Size = vp - vbegin;
// output import lookup table for each dll
for (struct Dll *e = dll_first(elf->imports); e;
e = dll_next(elf->imports, e)) {
struct Library *library = LIBRARY_CONTAINER(e);
library->idt->ImportLookupTable = vp - opthdr->ImageBase;
library->ilt = (uint64_t *)fp;
for (struct Dll *g = dll_first(library->funcs); g;
g = dll_next(library->funcs, g)) {
struct Func *func = FUNC_CONTAINER(g);
func->ilt = (uint64_t *)fp;
fp += sizeof(uint64_t);
vp += sizeof(uint64_t);
}
fp += sizeof(uint64_t);
vp += sizeof(uint64_t);
library->iltbytes = fp - (char *)library->ilt;
}
// output the hint name table
for (struct Dll *e = dll_first(elf->imports); e;
e = dll_next(elf->imports, e)) {
struct Library *library = LIBRARY_CONTAINER(e);
for (struct Dll *g = dll_first(library->funcs); g;
g = dll_next(library->funcs, g)) {
struct Func *func = FUNC_CONTAINER(g);
*func->ilt = vp - opthdr->ImageBase;
fp += sizeof(uint16_t); // hint
vp += sizeof(uint16_t);
size_t n = strlen(func->name);
fp = mempcpy(fp, func->name, n + 1);
vp += n + 1;
fp = ALIGN_FILE(fp, 2);
vp = ALIGN_VIRT(vp, 2);
}
}
// output the dll names
for (struct Dll *e = dll_first(elf->imports); e;
e = dll_next(elf->imports, e)) {
struct Library *library = LIBRARY_CONTAINER(e);
size_t n = strlen(library->name);
library->idt->DllNameRva = vp - opthdr->ImageBase;
fp = mempcpy(fp, library->name, n + 1);
vp += n + 1;
}
//////////////////////////////////////////////////////////////////////
idata_section->Misc.VirtualSize = vp - vbegin;
fp = ALIGN_FILE(fp, opthdr->FileAlignment);
idata_section->SizeOfRawData = fp - fbegin;
}
// output elf segment sections
for (struct Dll *e = dll_first(elf->segments); e;
e = dll_next(elf->segments, e)) {
struct Segment *segment = SEGMENT_CONTAINER(e);
vp = ALIGN_VIRT(vp, opthdr->SectionAlignment);
char *fbegin = fp;
int64_t vbegin = vp;
segment->pesection->VirtualAddress = vp - opthdr->ImageBase;
segment->pesection->PointerToRawData = fbegin - (char *)mzhdr;
//////////////////////////////////////////////////////////////////////
if (segment->prot == (PROT_READ | PROT_WRITE)) {
// sneak InputAddressTable into .data or .bss section
for (struct Dll *e = dll_first(elf->imports); e;
e = dll_next(elf->imports, e)) {
struct Library *library = LIBRARY_CONTAINER(e);
library->idt->ImportAddressTable = vp - opthdr->ImageBase;
fp = mempcpy(fp, library->ilt, library->iltbytes);
segment->hasprogbits = true;
for (struct Dll *g = dll_first(library->funcs); g;
g = dll_next(library->funcs, g)) {
struct Func *func = FUNC_CONTAINER(g);
func->symbol->st_value = vp;
vp += 8;
}
vp += 8;
}
fp = ALIGN_FILE(fp, segment->align);
vp = ALIGN_VIRT(vp, segment->align);
}
PickPeSectionName(segment->pesection->Name, elf, segment);
segment->vaddr_new_min = vp;
if (segment->vaddr_min <= entry->st_value &&
entry->st_value < segment->vaddr_max) {
opthdr->AddressOfEntryPoint =
vp + (entry->st_value - segment->vaddr_min) - opthdr->ImageBase;
}
if (segment->hasprogbits) {
segment->ptr_new = fp;
fp = mempcpy(fp, elf->map + segment->offset_min,
segment->offset_max - segment->offset_min);
}
vp += segment->vaddr_max - segment->vaddr_min;
segment->vaddr_new_max = vp;
segment->pesection->Characteristics = GetPeSectionCharacteristics(segment);
//////////////////////////////////////////////////////////////////////
segment->pesection->Misc.VirtualSize = vp - vbegin;
fp = ALIGN_FILE(fp, opthdr->FileAlignment);
segment->pesection->SizeOfRawData = fp - fbegin;
}
// compute relocations
RelocateElf(elf);
// compute informative sizes
// the windows executive ignores these fields, but they can't hurt.
for (int i = 0; i < filehdr->NumberOfSections; ++i) {
if (sections[i].Characteristics & kNtPeSectionCntCode) {
opthdr->SizeOfCode += sections[i].SizeOfRawData;
if (!opthdr->BaseOfCode) {
opthdr->BaseOfCode = sections[i].VirtualAddress;
}
}
if (sections[i].Characteristics & kNtPeSectionCntInitializedData) {
opthdr->SizeOfInitializedData += sections[i].SizeOfRawData;
}
if ((sections[i].Characteristics & kNtPeSectionCntUninitializedData) &&
sections[i].Misc.VirtualSize > sections[i].SizeOfRawData) {
opthdr->SizeOfUninitializedData +=
sections[i].Misc.VirtualSize - sections[i].SizeOfRawData;
}
}
// finish image
vp = ALIGN_VIRT(vp, opthdr->SectionAlignment);
opthdr->SizeOfImage = vp - opthdr->ImageBase;
return (struct ImagePointer){fp, vp};
}
static void GetOpts(int argc, char *argv[]) {
int opt;
while ((opt = getopt(argc, argv, "ho:D:R:S:")) != -1) {
switch (opt) {
case 'o':
outpath = optarg;
break;
case 'D':
stubpath = optarg;
break;
case 'S':
FLAG_SizeOfStackCommit = sizetol(optarg, 1024);
break;
case 'R':
FLAG_SizeOfStackReserve = sizetol(optarg, 1024);
break;
case 'h':
ShowUsage(0, 1);
default:
ShowUsage(1, 2);
}
}
if (!outpath) {
Die(prog, "need output path");
}
if (optind == argc) {
Die(prog, "missing input argument");
}
}
static void Pwrite(int fd, const void *data, size_t size, uint64_t offset) {
ssize_t rc;
const char *p, *e;
for (p = data, e = p + size; p < e; p += (size_t)rc, offset += (size_t)rc) {
if ((rc = pwrite(fd, p, e - p, offset)) == -1) {
DieSys(outpath);
}
}
}
int main(int argc, char *argv[]) {
#ifndef NDEBUG
ShowCrashReports();
#endif
// get program name
prog = argv[0];
if (!prog) prog = "elf2pe";
// process flags
GetOpts(argc, argv);
// translate executable
struct Elf *elf = OpenElf(argv[optind]);
char *buf = memalign(MAX_ALIGN, 134217728);
struct ImagePointer ip = GeneratePe(elf, buf, 0x00400000);
if (creat(outpath, 0755) == -1) DieSys(elf->path);
Pwrite(3, buf, ip.fp - buf, 0);
if (close(3)) DieSys(elf->path);
// PrintElf(elf);
}
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