Make posix_spawn faster on Windows

libc/calls/calls.mk

@@ -205,6 +205,8 @@ o/$(MODE)/libc/calls/swapcontext.o: libc/calls/swapcontext.S
 	@$(COMPILE) -AOBJECTIFY.S $(OBJECTIFY.S) $(OUTPUT_OPTION) -c $<
 o/$(MODE)/libc/calls/tailcontext.o: libc/calls/tailcontext.S
 	@$(COMPILE) -AOBJECTIFY.S $(OBJECTIFY.S) $(OUTPUT_OPTION) -c $<
+o/$(MODE)/libc/calls/switchstacks.o: libc/calls/switchstacks.S
+	@$(COMPILE) -AOBJECTIFY.S $(OBJECTIFY.S) $(OUTPUT_OPTION) -c $<
 
 LIBC_CALLS_LIBS = $(foreach x,$(LIBC_CALLS_ARTIFACTS),$($(x)))
 LIBC_CALLS_SRCS = $(foreach x,$(LIBC_CALLS_ARTIFACTS),$($(x)_SRCS))

libc/calls/copy_file_range.c

@@ -16,6 +16,7 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/atomic.h"
 #include "libc/calls/blockcancel.internal.h"
 #include "libc/calls/calls.h"
 #include "libc/calls/cp.internal.h"
@@ -33,7 +34,7 @@
 #include "libc/sysv/errfuns.h"
 
 static struct CopyFileRange {
-  _Atomic(uint32_t) once;
+  atomic_uint once;
   bool ok;
 } g_copy_file_range;
 

libc/calls/execve-nt.greg.c

@@ -22,8 +22,10 @@
 #include "libc/calls/ntspawn.h"
 #include "libc/calls/syscall-nt.internal.h"
 #include "libc/fmt/itoa.h"
+#include "libc/intrin/kprintf.h"
 #include "libc/intrin/strace.internal.h"
 #include "libc/intrin/weaken.h"
+#include "libc/macros.internal.h"
 #include "libc/mem/alloca.h"
 #include "libc/nt/accounting.h"
 #include "libc/nt/console.h"
@@ -34,16 +36,22 @@
 #include "libc/nt/struct/processinformation.h"
 #include "libc/nt/struct/startupinfo.h"
 #include "libc/nt/synchronization.h"
+#include "libc/nt/thread.h"
 #include "libc/nt/thunk/msabi.h"
 #include "libc/runtime/memtrack.internal.h"
 #include "libc/runtime/runtime.h"
+#include "libc/runtime/stack.h"
 #include "libc/sock/sock.h"
 #include "libc/str/str.h"
 #include "libc/sysv/consts/at.h"
 #include "libc/sysv/consts/map.h"
 #include "libc/sysv/consts/o.h"
 #include "libc/sysv/consts/ok.h"
+#include "libc/sysv/consts/sig.h"
 #include "libc/sysv/errfuns.h"
+#include "libc/thread/thread.h"
+
+#define keywords textwindows dontasan dontubsan dontinstrument
 
 extern long __klog_handle;
 
@@ -51,18 +59,58 @@ __msabi extern typeof(CloseHandle) *const __imp_CloseHandle;
 __msabi extern typeof(WaitForSingleObject) *const __imp_WaitForSingleObject;
 __msabi extern typeof(GetExitCodeProcess) *const __imp_GetExitCodeProcess;
 __msabi extern typeof(UnmapViewOfFile) *const __imp_UnmapViewOfFile;
+__msabi extern typeof(TerminateThread) *const __imp_TerminateThread;
 
-static dontinstrument __msabi bool32
-BlockExecveConsoleEvent(uint32_t dwCtrlType) {
-  // block SIGINT and SIGQUIT in execve() parent process
-  return true;
+wontreturn void __switch_stacks(intptr_t, long, long, long,
+                                void (*)(intptr_t, intptr_t, long, long),
+                                intptr_t);
+
+__msabi static keywords bool32 sys_execve_nt_event(uint32_t dwCtrlType) {
+  return true;  // block sigint and sigquit in execve() parent process
 }
 
-textwindows int sys_execve_nt(const char *program, char *const argv[],
-                              char *const envp[]) {
+static keywords void PurgeHandle(intptr_t h) {
+  if (h && h != -1) {
+    __imp_CloseHandle(h);
+  }
+}
+
+static keywords void PurgeThread(intptr_t h) {
+  if (h && h != -1) {
+    __imp_TerminateThread(h, SIGKILL);
+    __imp_CloseHandle(h);
+  }
+}
+
+// this function runs on the original tiny stack that windows gave us.
+// we need to keep the original process alive simply to pass an int32.
+// so we unmap all memory to avoid getting a double whammy after fork.
+static keywords void sys_execve_nt_relay(intptr_t h, long b, long c, long d) {
+  uint32_t i, dwExitCode;
+  __imp_SetConsoleCtrlHandler((void *)sys_execve_nt_event, 1);
+  PurgeThread(g_fds.stdin.thread);
+  PurgeHandle(g_fds.stdin.reader);
+  PurgeHandle(g_fds.stdin.writer);
+  PurgeHandle(g_fds.p[0].handle);
+  PurgeHandle(g_fds.p[1].handle);
+  PurgeHandle(g_fds.p[2].handle);
+  for (i = 0; i < _mmi.i; ++i) {
+    __imp_UnmapViewOfFile((void *)((uintptr_t)_mmi.p[i].x << 16));
+    PurgeHandle(_mmi.p[i].h);
+  }
+  do {
+    __imp_WaitForSingleObject(h, -1);
+    dwExitCode = kNtStillActive;
+    __imp_GetExitCodeProcess(h, &dwExitCode);
+  } while (dwExitCode == kNtStillActive);
+  __imp_ExitProcess(dwExitCode);
+  __builtin_unreachable();
+}
+
+keywords int sys_execve_nt(const char *program, char *const argv[],
+                           char *const envp[]) {
   int rc;
   size_t i;
-  uint32_t dwExitCode;
   char progbuf[PATH_MAX];
   struct NtStartupInfo startinfo;
   struct NtProcessInformation procinfo;
@@ -89,16 +137,26 @@ textwindows int sys_execve_nt(const char *program, char *const argv[],
   //////////////////////////////////////////////////////////////////////////////
   // execve operation is unrecoverable from this point
 
+  if (_weaken(pthread_kill_siblings_np)) {
+    _weaken(pthread_kill_siblings_np)();
+  }
+
   // close non-stdio and cloexec handles
   for (i = 0; i < g_fds.n; ++i) {
     if (g_fds.p[i].kind == kFdEmpty) {
       g_fds.p[i].handle = -1;
     } else if (i > 2 || (g_fds.p[i].flags & O_CLOEXEC)) {
-      __imp_CloseHandle(g_fds.p[i].handle);
+      PurgeHandle(g_fds.p[i].handle);
       g_fds.p[i].handle = -1;
     }
   }
 
+  if (_weaken(__klog_handle) &&        //
+      *_weaken(__klog_handle) != 0 &&  //
+      *_weaken(__klog_handle) != -1) {
+    PurgeHandle(*_weaken(__klog_handle));
+  }
+
   int bits;
   char buf[32], *v = 0;
   if (_weaken(socket)) {
@@ -117,12 +175,6 @@ textwindows int sys_execve_nt(const char *program, char *const argv[],
   startinfo.hStdOutput = g_fds.p[1].handle;
   startinfo.hStdError = g_fds.p[2].handle;
 
-  if (_weaken(__klog_handle) &&        //
-      *_weaken(__klog_handle) != 0 &&  //
-      *_weaken(__klog_handle) != -1) {
-    __imp_CloseHandle(*_weaken(__klog_handle));
-  }
-
   // spawn the process
   rc = ntspawn(program, argv, envp, v, 0, 0, true, 0, 0, &startinfo, &procinfo);
   if (rc == -1) {
@@ -131,19 +183,8 @@ textwindows int sys_execve_nt(const char *program, char *const argv[],
   }
 
   //////////////////////////////////////////////////////////////////////////////
-  // zombie shell process remains, to wait for child and propagate its exit
-  // code
+  // zombify this process which lingers on to relay the status code
 
-  __imp_CloseHandle(g_fds.p[0].handle);
-  __imp_CloseHandle(g_fds.p[1].handle);
-  __imp_CloseHandle(procinfo.hThread);
-  __imp_SetConsoleCtrlHandler((void *)BlockExecveConsoleEvent, 1);
-  do {
-    __imp_WaitForSingleObject(procinfo.hProcess, -1);
-    dwExitCode = kNtStillActive;
-    __imp_GetExitCodeProcess(procinfo.hProcess, &dwExitCode);
-  } while (dwExitCode == kNtStillActive);
-  __imp_CloseHandle(procinfo.hProcess);
-  __imp_ExitProcess(dwExitCode);
-  notpossible;
+  PurgeHandle(procinfo.hThread);
+  __switch_stacks(procinfo.hProcess, 0, 0, 0, sys_execve_nt_relay, __oldstack);
 }

libc/calls/raise.c

@@ -21,6 +21,8 @@
 #include "libc/calls/syscall-sysv.internal.h"
 #include "libc/dce.h"
 #include "libc/intrin/strace.internal.h"
+#include "libc/intrin/weaken.h"
+#include "libc/nt/runtime.h"
 #include "libc/runtime/internal.h"
 #include "libc/sysv/consts/sicode.h"
 #include "libc/sysv/consts/sig.h"
@@ -62,10 +64,20 @@ int raise(int sig) {
     RaiseSigFpe();
     rc = 0;
 #endif
-  } else if (!IsWindows() && !IsMetal()) {
+  } else if (IsLinux() || IsXnu() || IsFreebsd() || IsOpenbsd() || IsNetbsd()) {
     rc = sys_tkill(gettid(), sig, 0);
+  } else if (IsWindows() || IsMetal()) {
+    if (IsWindows() && sig == SIGKILL) {
+      // TODO(jart): Isn't this implemented by __sig_raise()?
+      if (_weaken(__restore_console_win32)) {
+        _weaken(__restore_console_win32)();
+      }
+      ExitProcess(sig);
+    } else {
+      rc = __sig_raise(sig, SI_TKILL);
+    }
   } else {
-    rc = __sig_raise(sig, SI_TKILL);
+    __builtin_unreachable();
   }
   STRACE("...raise(%G) → %d% m", sig, rc);
   return rc;

libc/calls/struct/fd.internal.h

@@ -41,6 +41,7 @@ struct StdinRelay {
   int64_t handle; /* should == g_fds.p[0].handle */
   int64_t reader; /* ReadFile() use this instead */
   int64_t writer; /* only used by WinStdinThread */
+  int64_t thread; /* handle for the stdio thread */
 };
 
 struct Fds {

libc/calls/switchstacks.S

@@ -1,7 +1,7 @@
-/*-*- 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│
+/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8     -*-│
+│vi: set et ft=asm ts=8 tw=8 fenc=utf-8                                     :vi│
 ╞══════════════════════════════════════════════════════════════════════════════╡
-│ Copyright 2022 Justine Alexandra Roberts Tunney                              │
+│ 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         │
@@ -16,38 +16,19 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
-#include "libc/calls/calls.h"
-#include "libc/calls/sig.internal.h"
-#include "libc/calls/syscall-sysv.internal.h"
-#include "libc/calls/syscall_support-sysv.internal.h"
-#include "libc/dce.h"
-#include "libc/intrin/strace.internal.h"
-#include "libc/sysv/consts/sicode.h"
+#include "libc/macros.internal.h"
 
-// OpenBSD has an optional `tib` parameter for extra safety
-int __tkill(int tid, int sig, void *tib) {
-  int rc;
-  if (!IsWindows() && !IsMetal()) {
-    rc = sys_tkill(tid, sig, tib);
-  } else {
-    rc = __sig_add(tid, sig, SI_TKILL);
-  }
-  STRACE("tkill(%d, %G) → %d% m", tid, sig, rc);
-  return rc;
-}
-
-/**
- * Kills thread.
- *
- * @param tid is thread id
- * @param sig does nothing on xnu
- * @return 0 on success, or -1 w/ errno
- * @raise EAGAIN if `RLIMIT_SIGPENDING` was exceeded
- * @raise EINVAL if `tid` or `sig` were invalid
- * @raise ESRCH if no such `tid` existed
- * @raise EPERM if permission was denied
- * @asyncsignalsafe
- */
-int tkill(int tid, int sig) {
-  return __tkill(tid, sig, 0);
-}
+__switch_stacks:
+#ifdef __x86_64__
+	mov	%r9,%rsp
+	and	$-16,%rsp
+	xor	%rbp,%rbp
+	call	*%r8
+#elif defined(__aarch64__)
+	and	sp,x5,#-16
+	mov	x29,0
+	blr	x4
+#else
+#error "unsupported architecture"
+#endif
+	.endfn	__switch_stacks,globl

libc/calls/winstdin1.c

@@ -135,8 +135,8 @@ dontasan dontubsan dontinstrument textwindows void WinMainStdin(void) {
     NTTRACE("<stdin> CreateThread failed");
     return;
   }
-  __imp_CloseHandle(hThread);
-  g_fds.stdin.handle = hStdin;
+  g_fds.stdin.thread = hStdin;
+  g_fds.stdin.handle = hThread;
   g_fds.stdin.reader = hReader;
   g_fds.stdin.writer = hWriter;
   g_fds.stdin.inisem = hSemaphore;