/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 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 "ape/sections.internal.h"
#include "libc/assert.h"
#include "libc/atomic.h"
#include "libc/calls/internal.h"
#include "libc/calls/sig.internal.h"
#include "libc/calls/state.internal.h"
#include "libc/calls/syscall_support-nt.internal.h"
#include "libc/errno.h"
#include "libc/fmt/itoa.h"
#include "libc/intrin/atomic.h"
#include "libc/intrin/directmap.h"
#include "libc/intrin/kprintf.h"
#include "libc/intrin/maps.h"
#include "libc/intrin/strace.h"
#include "libc/intrin/tree.h"
#include "libc/intrin/weaken.h"
#include "libc/macros.h"
#include "libc/nt/createfile.h"
#include "libc/nt/enum/accessmask.h"
#include "libc/nt/enum/creationdisposition.h"
#include "libc/nt/enum/filemapflags.h"
#include "libc/nt/enum/pageflags.h"
#include "libc/nt/enum/startf.h"
#include "libc/nt/errors.h"
#include "libc/nt/ipc.h"
#include "libc/nt/memory.h"
#include "libc/nt/process.h"
#include "libc/nt/runtime.h"
#include "libc/nt/signals.h"
#include "libc/nt/struct/ntexceptionpointers.h"
#include "libc/nt/thread.h"
#include "libc/nt/thunk/msabi.h"
#include "libc/proc/ntspawn.h"
#include "libc/proc/proc.internal.h"
#include "libc/runtime/internal.h"
#include "libc/runtime/memtrack.internal.h"
#include "libc/runtime/runtime.h"
#include "libc/runtime/stack.h"
#include "libc/runtime/symbols.internal.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/at.h"
#include "libc/sysv/consts/limits.h"
#include "libc/sysv/consts/map.h"
#include "libc/sysv/consts/prot.h"
#include "libc/sysv/consts/sig.h"
#include "libc/sysv/errfuns.h"
#include "libc/thread/itimer.internal.h"
#include "libc/thread/posixthread.internal.h"
#include "libc/thread/tls.h"
#include "libc/thread/tls2.internal.h"
#ifdef __x86_64__
extern long __klog_handle;
void WipeKeystrokes(void);
__msabi extern typeof(GetCurrentProcessId) *const __imp_GetCurrentProcessId;
static textwindows wontreturn void AbortFork(const char *func, void *addr) {
#if SYSDEBUG
kprintf("fork() %!s(%lx) failed with win32 error %u\n", func, addr,
GetLastError());
#endif
TerminateThisProcess(SIGSTKFLT);
}
static textwindows char16_t *ParseInt(char16_t *p, int64_t *x) {
*x = 0;
while (*p == ' ')
p++;
while ('0' <= *p && *p <= '9') {
*x *= 10;
*x += *p++ - '0';
}
return p;
}
static inline textwindows ssize_t ForkIo(int64_t h, char *p, size_t n,
bool32 (*f)(int64_t, void *, uint32_t,
uint32_t *,
struct NtOverlapped *)) {
size_t i;
uint32_t x;
for (i = 0; i < n; i += x) {
if (!f(h, p + i, n - i, &x, 0))
return __winerr();
if (!x)
break;
}
return i;
}
static dontinline textwindows ssize_t ForkIo2(
int64_t h, void *buf, size_t n,
bool32 (*fn)(int64_t, void *, uint32_t, uint32_t *, struct NtOverlapped *),
const char *sf, bool ischild) {
ssize_t rc = ForkIo(h, buf, n, fn);
if (ischild) {
// prevent crashes
__tls_enabled = false;
__pid = __imp_GetCurrentProcessId();
__klog_handle = 0;
__maps.maps = 0;
}
NTTRACE("%s(%ld, %p, %'zu) → %'zd% m", sf, h, buf, n, rc);
return rc;
}
static dontinline textwindows bool WriteAll(int64_t h, void *buf, size_t n) {
bool ok;
ok = ForkIo2(h, buf, n, (void *)WriteFile, "WriteFile", false) != -1;
if (!ok) {
STRACE("fork() failed in parent due to WriteAll(%ld, %p, %'zu) → %u", h,
buf, n, GetLastError());
__print_maps(0);
}
return ok;
}
static textwindows dontinline void ReadOrDie(int64_t h, void *buf, size_t n) {
ssize_t got;
if ((got = ForkIo2(h, buf, n, ReadFile, "ReadFile", true)) == -1)
AbortFork("ReadFile1", buf);
if (got != n)
AbortFork("ReadFile2", buf);
}
static textwindows int64_t MapOrDie(uint32_t prot, uint64_t size) {
int64_t h;
for (;;) {
if ((h = CreateFileMapping(-1, 0, prot, size >> 32, size, 0)))
return h;
if (GetLastError() == kNtErrorAccessDenied) {
switch (prot) {
case kNtPageExecuteWritecopy:
prot = kNtPageWritecopy;
continue;
case kNtPageExecuteReadwrite:
prot = kNtPageReadwrite;
continue;
case kNtPageExecuteRead:
prot = kNtPageReadonly;
continue;
default:
break;
}
}
AbortFork("MapOrDie", (void *)size);
}
}
static textwindows void ViewOrDie(int64_t h, uint32_t access, size_t pos,
size_t size, void *base) {
TryAgain:
if (!MapViewOfFileEx(h, access, pos >> 32, pos, size, base)) {
if ((access & kNtFileMapExecute) &&
GetLastError() == kNtErrorAccessDenied) {
access &= ~kNtFileMapExecute;
goto TryAgain;
}
AbortFork("ViewOrDie", base);
}
}
static __msabi textwindows int OnForkCrash(struct NtExceptionPointers *ep) {
kprintf("error: fork() child crashed!%n"
"\tExceptionCode = %#x%n"
"\tRip = %x%n",
ep->ExceptionRecord->ExceptionCode,
ep->ContextRecord ? ep->ContextRecord->Rip : -1);
TerminateThisProcess(SIGSTKFLT);
}
static textwindows void *Malloc(size_t size) {
return HeapAlloc(GetProcessHeap(), 0, size);
}
textwindows void WinMainForked(void) {
jmp_buf jb;
int64_t reader;
int64_t savetsc;
uint32_t varlen;
char16_t fvar[21 + 1 + 21 + 1];
struct Fds *fds = __veil("r", &g_fds);
// check to see if the process was actually forked
// this variable should have the pipe handle numba
varlen = GetEnvironmentVariable(u"_FORK", fvar, ARRAYLEN(fvar));
if (!varlen || varlen >= ARRAYLEN(fvar))
return;
/* STRACE("WinMainForked()"); */
SetEnvironmentVariable(u"_FORK", NULL);
#if SYSDEBUG
int64_t oncrash = AddVectoredExceptionHandler(1, (void *)OnForkCrash);
#endif
ParseInt(fvar, &reader);
// read the cpu state from the parent process & plus
ReadOrDie(reader, jb, sizeof(jb));
// read memory mappings from parent process
struct Tree *maps = 0;
for (;;) {
struct Map *map = Malloc(sizeof(struct Map));
ReadOrDie(reader, map, sizeof(struct Map));
if (map->addr == MAP_FAILED)
break;
tree_insert(&maps, &map->tree, __maps_compare);
}
// map memory into process
int granularity = __gransize;
for (struct Tree *e = tree_first(maps); e; e = tree_next(e)) {
struct Map *map = MAP_TREE_CONTAINER(e);
if ((uintptr_t)map->addr & (granularity - 1))
continue;
// get true length in case mprotect() chopped up actual win32 map
size_t size = map->size;
for (struct Tree *e2 = tree_next(e); e2; e2 = tree_next(e2)) {
struct Map *map2 = MAP_TREE_CONTAINER(e2);
if (map2->hand == -1 && map->addr + size == map2->addr) {
size += map2->size;
} else {
break;
}
}
// obtain the most permissive access possible
unsigned prot, access;
if (map->readonlyfile) {
prot = kNtPageExecuteRead;
access = kNtFileMapRead | kNtFileMapExecute;
} else {
prot = kNtPageExecuteReadwrite;
access = kNtFileMapWrite | kNtFileMapExecute;
}
if ((map->flags & MAP_TYPE) != MAP_SHARED) {
// we don't need to close the map handle because sys_mmap_nt
// doesn't mark it inheritable across fork() for MAP_PRIVATE
map->hand = MapOrDie(prot, size);
ViewOrDie(map->hand, access, 0, size, map->addr);
ReadOrDie(reader, map->addr, size);
} else {
// we can however safely inherit MAP_SHARED with zero copy
ViewOrDie(map->hand, access, map->off, size, map->addr);
}
}
// read the .data and .bss program image sections
savetsc = kStartTsc;
ReadOrDie(reader, __data_start, __data_end - __data_start);
ReadOrDie(reader, __bss_start, __bss_end - __bss_start);
kStartTsc = savetsc;
__tls_enabled = false;
// fixup memory manager
__maps.maps = 0;
__maps.freed = 0;
__maps.count = 0;
__maps.pages = 0;
for (struct Tree *e = tree_first(maps); e; e = tree_next(e)) {
struct Map *map = MAP_TREE_CONTAINER(e);
__maps.count += 1;
__maps.pages += (map->size + __pagesize - 1) / __pagesize;
unsigned old_protect;
if (!VirtualProtect(map->addr, map->size, __prot2nt(map->prot, map->iscow),
&old_protect))
AbortFork("VirtualProtect", map->addr);
}
__maps.maps = maps;
__maps_init();
// mitosis complete
if (!CloseHandle(reader))
AbortFork("CloseHandle", (void *)reader);
// rewrap the stdin named pipe hack
// since the handles closed on fork
fds->p[0].handle = GetStdHandle(kNtStdInputHandle);
fds->p[1].handle = GetStdHandle(kNtStdOutputHandle);
fds->p[2].handle = GetStdHandle(kNtStdErrorHandle);
// restore the crash reporting stuff
#if SYSDEBUG
RemoveVectoredExceptionHandler(oncrash);
#endif
if (_weaken(__sig_init))
_weaken(__sig_init)();
// jump back into function below
longjmp(jb, 1);
}
textwindows int sys_fork_nt(uint32_t dwCreationFlags) {
char ok;
jmp_buf jb;
char **args;
int rc = -1;
struct Proc *proc;
struct CosmoTib *tib;
char16_t pipename[64];
int64_t reader, writer;
struct NtStartupInfo startinfo;
struct NtProcessInformation procinfo;
char *p, forkvar[6 + 21 + 1 + 21 + 1];
tib = __get_tls();
if (!(proc = __proc_new()))
return -1;
ftrace_enabled(-1);
strace_enabled(-1);
if (!setjmp(jb)) {
reader = CreateNamedPipe(__create_pipe_name(pipename), kNtPipeAccessInbound,
kNtPipeTypeByte | kNtPipeReadmodeByte, 1, PIPE_BUF,
PIPE_BUF, 0, &kNtIsInheritable);
writer = CreateFile(pipename, kNtGenericWrite, 0, 0, kNtOpenExisting, 0, 0);
if (reader != -1 && writer != -1) {
p = stpcpy(forkvar, "_FORK=");
p = FormatUint64(p, reader);
bzero(&startinfo, sizeof(startinfo));
startinfo.cb = sizeof(struct NtStartupInfo);
startinfo.dwFlags = kNtStartfUsestdhandles;
startinfo.hStdInput = g_fds.p[0].handle;
startinfo.hStdOutput = g_fds.p[1].handle;
startinfo.hStdError = g_fds.p[2].handle;
args = __argv;
#if SYSDEBUG
int i;
// If --strace was passed to this program, then propagate it the
// forked process since the flag was removed by __intercept_flag
if (strace_enabled(0) > 0) {
int n;
for (n = 0; args[n];)
++n;
#pragma GCC push_options
#pragma GCC diagnostic ignored "-Walloca-larger-than="
int nbytes = (n + 2) * sizeof(char *);
char **args2 = alloca(nbytes);
CheckLargeStackAllocation(args2, nbytes);
#pragma GCC pop_options
for (i = 0; i < n; ++i)
args2[i] = args[i];
args2[i++] = "--strace";
args2[i] = 0;
args = args2;
}
#endif
NTTRACE("STARTING SPAWN");
int spawnrc = ntspawn(&(struct NtSpawnArgs){
AT_FDCWD, GetProgramExecutableName(), args, environ,
(char *[]){forkvar, 0}, dwCreationFlags, 0, 0, 0, 0, &startinfo,
&procinfo});
if (spawnrc != -1) {
CloseHandle(procinfo.hThread);
ok = WriteAll(writer, jb, sizeof(jb));
// this list will be populated with the maps we're transferring
for (struct Map *map = __maps_first(); ok && map;
map = __maps_next(map)) {
if (map->flags & MAP_NOFORK)
continue;
if (MAX((char *)__executable_start, map->addr) <
MIN((char *)_end, map->addr + map->size))
continue; // executable image is loaded by windows
ok = WriteAll(writer, map, sizeof(*map));
}
// send a terminating Map struct to child
if (ok) {
struct Map map;
map.addr = MAP_FAILED;
ok = WriteAll(writer, &map, sizeof(map));
}
// now write content of each map to child
int granularity = __gransize;
for (struct Map *map = __maps_first(); ok && map;
map = __maps_next(map)) {
if (map->flags & MAP_NOFORK)
continue;
// we only need to worry about the base mapping
if ((uintptr_t)map->addr & (granularity - 1))
continue;
if (MAX((char *)__executable_start, map->addr) <
MIN((char *)_end, map->addr + map->size))
continue; // executable image is loaded by windows
// shared mappings don't need to be copied
if ((map->flags & MAP_TYPE) == MAP_SHARED)
continue;
// get true length in case mprotect() chopped up actual win32 map
size_t size = map->size;
for (struct Map *map2 = __maps_next(map); map2;
map2 = __maps_next(map2)) {
if (map2->hand == -1 && map->addr + size == map2->addr) {
size += map2->size;
} else {
break;
}
}
for (struct Map *map2 = map; ok && map2; map2 = __maps_next(map2)) {
if (!(map2->prot & PROT_READ))
if (map->addr >= map2->addr && map->addr < map->addr + size)
ok = VirtualProtect(
map2->addr, map2->size,
__prot2nt(map2->prot | PROT_READ, map2->iscow),
&map2->visited);
}
if (ok)
ok = WriteAll(writer, map->addr, size);
for (struct Map *map2 = map; ok && map2; map2 = __maps_next(map2)) {
if (!(map2->prot & PROT_READ))
if (map->addr >= map2->addr && map->addr < map->addr + size)
ok = VirtualProtect(map2->addr, map2->size, map2->visited,
&map2->visited);
}
}
if (ok)
ok = WriteAll(writer, __data_start, __data_end - __data_start);
if (ok)
ok = WriteAll(writer, __bss_start, __bss_end - __bss_start);
if (ok) {
if (!CloseHandle(writer))
ok = false;
writer = -1;
}
if (ok) {
proc->wasforked = true;
proc->handle = procinfo.hProcess;
rc = proc->pid = procinfo.dwProcessId;
__proc_add(proc);
} else {
TerminateProcess(procinfo.hProcess, SIGKILL);
CloseHandle(procinfo.hProcess);
rc = -1;
}
}
}
if (reader != -1)
CloseHandle(reader);
if (writer != -1)
CloseHandle(writer);
if (rc == -1 && errno != ENOMEM)
eagain(); // posix fork() only specifies two errors
} else {
rc = 0;
// re-apply code morphing for thread-local storage
__tls_index = TlsAlloc();
__set_tls_win32(tib);
__morph_tls();
__tls_enabled = true;
// the child's pending signals is initially empty
atomic_store_explicit(&__sig.pending, 0, memory_order_relaxed);
atomic_store_explicit(&tib->tib_sigpending, 0, memory_order_relaxed);
// re-apply code morphing for function tracing
if (ftrace_stackdigs) {
_weaken(__hook)(_weaken(ftrace_hook), _weaken(GetSymbolTable)());
}
// reset core runtime services
__proc_wipe();
WipeKeystrokes();
if (_weaken(__itimer_wipe))
_weaken(__itimer_wipe)();
// notify pthread join
atomic_store_explicit(&_pthread_static.ptid, GetCurrentThreadId(),
memory_order_release);
}
if (rc == -1)
dll_make_first(&__proc.free, &proc->elem);
ftrace_enabled(+1);
strace_enabled(+1);
return rc;
}
#endif /* __x86_64__ */