Make win32 i/o signals atomic and longjmp() safe

Author: jart

Makefile

@@ -374,6 +374,7 @@ COSMOPOLITAN_OBJECTS =			\
 	THIRD_PARTY_NSYNC_MEM		\
 	LIBC_MEM			\
 	THIRD_PARTY_DLMALLOC		\
+	LIBC_DLOPEN			\
 	LIBC_RUNTIME			\
 	THIRD_PARTY_NSYNC		\
 	LIBC_ELF			\

libc/calls/interrupts-nt.c renamed to libc/calls/checkcancel.c

@@ -17,10 +17,8 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/internal.h"
-#include "libc/calls/sig.internal.h"
 #include "libc/intrin/atomic.h"
 #include "libc/intrin/weaken.h"
-#include "libc/sysv/errfuns.h"
 #include "libc/thread/posixthread.internal.h"
 #ifdef __x86_64__
 
@@ -34,14 +32,4 @@ textwindows int _check_cancel(void) {
   return 0;
 }
 
-textwindows int _check_signal(bool restartable) {
-  int status;
-  if (_check_cancel() == -1) return -1;
-  if (!_weaken(__sig_check)) return 0;
-  if (!(status = _weaken(__sig_check)())) return 0;
-  if (_check_cancel() == -1) return -1;
-  if (status == 2 && restartable) return 0;
-  return eintr();
-}
-
 #endif /* __x86_64__ */

libc/calls/checksignal.c

@@ -0,0 +1,35 @@
+/*-*- 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/calls/internal.h"
+#include "libc/calls/sig.internal.h"
+#include "libc/intrin/weaken.h"
+#include "libc/sysv/errfuns.h"
+#ifdef __x86_64__
+
+textwindows int _check_signal(bool restartable) {
+  int status;
+  if (_check_cancel() == -1) return -1;
+  if (!_weaken(__sig_check)) return 0;
+  if (!(status = _weaken(__sig_check)())) return 0;
+  if (_check_cancel() == -1) return -1;
+  if (status == 2 && restartable) return 0;
+  return eintr();
+}
+
+#endif /* __x86_64__ */

libc/calls/park.c

@@ -16,50 +16,40 @@
 │ 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/calls/internal.h"
-#include "libc/calls/struct/sigset.internal.h"
-#include "libc/calls/syscall_support-nt.internal.h"
-#include "libc/errno.h"
+#include "libc/calls/sig.internal.h"
 #include "libc/intrin/atomic.h"
-#include "libc/nt/enum/wait.h"
-#include "libc/nt/runtime.h"
 #include "libc/nt/synchronization.h"
+#include "libc/sysv/consts/sicode.h"
 #include "libc/sysv/errfuns.h"
 #include "libc/thread/posixthread.internal.h"
-#include "libc/thread/thread.h"
-#include "libc/thread/tls.h"
 #ifdef __x86_64__
 
+// returns 0 on timeout or spurious wakeup
+// raises EINTR if a signal delivery interrupted wait operation
+// raises ECANCELED if this POSIX thread was canceled in masked mode
 static textwindows int _park_thread(uint32_t msdelay, sigset_t waitmask,
                                     bool restartable) {
-  int rc;
-  int64_t sem;
-  sigset_t om;
-  uint32_t wi;
-  struct PosixThread *pt;
-  pt = _pthread_self();
-  pt->pt_flags &= ~PT_RESTARTABLE;
-  if (restartable) pt->pt_flags |= PT_RESTARTABLE;
-  pt->pt_semaphore = sem = CreateSemaphore(0, 0, 1, 0);
-  pthread_cleanup_push((void *)CloseHandle, (void *)sem);
-  atomic_store_explicit(&pt->pt_blocker, PT_BLOCKER_SEM, memory_order_release);
-  om = __sig_beginwait(waitmask);
-  if ((rc = _check_signal(restartable)) != -1) {
-    if ((wi = WaitForSingleObject(sem, msdelay)) != -1u) {
-      if (restartable && !(pt->pt_flags & PT_RESTARTABLE)) rc = eintr();
-      rc |= _check_signal(restartable);
-    } else {
-      rc = __winerr();
-    }
+  int sig;
+  if (_check_cancel() == -1) return -1;
+  if ((sig = __sig_get(waitmask))) {
+    int handler_was_called = __sig_relay(sig, SI_KERNEL, waitmask);
+    if (_check_cancel() == -1) return -1;
+    if (!restartable || handler_was_called == 1) return eintr();
   }
-  __sig_finishwait(om);
-  atomic_store_explicit(&pt->pt_blocker, PT_BLOCKER_CPU, memory_order_release);
-  pt->pt_flags &= ~PT_RESTARTABLE;
-  pthread_cleanup_pop(true);
-  pt->pt_semaphore = 0;
-  return rc;
+  int expect = 0;
+  atomic_int futex = 0;
+  struct PosixThread *pt = _pthread_self();
+  pt->pt_blkmask = waitmask;
+  atomic_store_explicit(&pt->pt_blocker, &futex, memory_order_release);
+  bool32 ok = WaitOnAddress(&futex, &expect, sizeof(int), msdelay);
+  atomic_store_explicit(&pt->pt_blocker, 0, memory_order_release);
+  if (ok && (sig = __sig_get(waitmask))) {
+    int handler_was_called = __sig_relay(sig, SI_KERNEL, waitmask);
+    if (_check_cancel() == -1) return -1;
+    if (!restartable || handler_was_called == 1) return eintr();
+  }
+  return 0;
 }
 
 textwindows int _park_norestart(uint32_t msdelay, sigset_t waitmask) {

libc/calls/read-nt.c

@@ -44,13 +44,15 @@
 #include "libc/nt/enum/creationdisposition.h"
 #include "libc/nt/enum/filesharemode.h"
 #include "libc/nt/enum/vk.h"
+#include "libc/nt/enum/wait.h"
 #include "libc/nt/errors.h"
 #include "libc/nt/runtime.h"
 #include "libc/nt/struct/inputrecord.h"
 #include "libc/nt/synchronization.h"
 #include "libc/str/str.h"
 #include "libc/str/utf16.h"
 #include "libc/sysv/consts/o.h"
+#include "libc/sysv/consts/sicode.h"
 #include "libc/sysv/consts/sig.h"
 #include "libc/sysv/errfuns.h"
 #include "libc/thread/posixthread.internal.h"
@@ -718,10 +720,10 @@ static textwindows bool DigestConsoleInput(char *data, size_t size, int *rc) {
 }
 
 static textwindows int WaitForConsole(struct Fd *f, sigset_t waitmask) {
-  int rc;
-  sigset_t m;
+  int sig;
   int64_t sem;
-  uint32_t ms = -1u;
+  uint32_t wi, ms = -1;
+  int handler_was_called;
   struct PosixThread *pt;
   if (!__ttyconf.vmin) {
     if (!__ttyconf.vtime) {
@@ -733,39 +735,42 @@ static textwindows int WaitForConsole(struct Fd *f, sigset_t waitmask) {
   if (f->flags & _O_NONBLOCK) {
     return eagain();  // standard unix non-blocking
   }
+  if (_check_cancel() == -1) return -1;
+  if ((sig = __sig_get(waitmask))) {
+    handler_was_called = __sig_relay(sig, SI_KERNEL, waitmask);
+    if (_check_cancel() == -1) return -1;
+    if (handler_was_called != 1) return -2;
+    return eintr();
+  }
   pt = _pthread_self();
-  pt->pt_flags |= PT_RESTARTABLE;
   pt->pt_semaphore = sem = CreateSemaphore(0, 0, 1, 0);
   pthread_cleanup_push((void *)CloseHandle, (void *)sem);
+  pt->pt_blkmask = waitmask;
   atomic_store_explicit(&pt->pt_blocker, PT_BLOCKER_SEM, memory_order_release);
-  m = __sig_beginwait(waitmask);
-  if ((rc = _check_signal(true)) != -1) {
-    int64_t hands[2] = {sem, __keystroke.cin};
-    if (WaitForMultipleObjects(2, hands, 0, ms) != -1u) {
-      if (!(pt->pt_flags & PT_RESTARTABLE)) rc = eintr();
-      rc |= _check_signal(true);
-    } else {
-      rc = __winerr();
-    }
-  }
-  __sig_finishwait(m);
-  atomic_store_explicit(&pt->pt_blocker, PT_BLOCKER_CPU, memory_order_release);
-  pt->pt_flags &= ~PT_RESTARTABLE;
+  wi = WaitForMultipleObjects(2, (int64_t[2]){__keystroke.cin, sem}, 0, ms);
+  atomic_store_explicit(&pt->pt_blocker, 0, memory_order_release);
   pthread_cleanup_pop(true);
-  return rc;
+  if (wi == kNtWaitTimeout) return 0;  // vtime elapsed
+  if (wi == 0) return -2;              // console data
+  if (wi != 1) return __winerr();      // wait failed
+  if (!(sig = __sig_get(waitmask))) return eintr();
+  handler_was_called = __sig_relay(sig, SI_KERNEL, waitmask);
+  if (_check_cancel() == -1) return -1;
+  if (handler_was_called != 1) return -2;
+  return eintr();
 }
 
 static textwindows ssize_t ReadFromConsole(struct Fd *f, void *data,
                                            size_t size, sigset_t waitmask) {
   int rc;
-  bool done = false;
   InitConsole();
   do {
     LockKeystrokes();
     IngestConsoleInput();
-    done = DigestConsoleInput(data, size, &rc);
+    bool done = DigestConsoleInput(data, size, &rc);
     UnlockKeystrokes();
-  } while (!done && !(rc = WaitForConsole(f, waitmask)));
+    if (done) return rc;
+  } while ((rc = WaitForConsole(f, waitmask)) == -2);
   return rc;
 }
 
@@ -823,7 +828,6 @@ static textwindows ssize_t sys_read_nt2(int fd, const struct iovec *iov,
       total += rc;
       if (opt_offset != -1) opt_offset += rc;
       if (rc < iov[i].iov_len) break;
-      waitmask = -1;  // disable eintr/ecanceled for remaining iovecs
     }
     return total;
   } else {