Avoid linking win32 signals impl

This shaves ~4kb off o/tiny/examples/hello2.com by avoiding linking the
WIN32 signals polyfill unless sigaction() is being used.

See #965

libc/calls/park.c

@@ -19,6 +19,7 @@
 #include "libc/calls/internal.h"
 #include "libc/calls/sig.internal.h"
 #include "libc/intrin/atomic.h"
+#include "libc/intrin/weaken.h"
 #include "libc/nt/synchronization.h"
 #include "libc/sysv/consts/sicode.h"
 #include "libc/sysv/errfuns.h"
@@ -30,9 +31,11 @@
 // 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 sig;
+  int sig, handler_was_called;
   if (_check_cancel() == -1) return -1;
-  if ((sig = __sig_get(waitmask))) goto HandleSignal;
+  if (_weaken(__sig_get) && (sig = _weaken(__sig_get)(waitmask))) {
+    goto HandleSignal;
+  }
   int expect = 0;
   atomic_int futex = 0;
   struct PosixThread *pt = _pthread_self();
@@ -40,9 +43,9 @@ static textwindows int _park_thread(uint32_t msdelay, sigset_t 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))) {
+  if (ok && _weaken(__sig_get) && (sig = _weaken(__sig_get)(waitmask))) {
   HandleSignal:
-    int handler_was_called = __sig_relay(sig, SI_KERNEL, waitmask);
+    handler_was_called = _weaken(__sig_relay)(sig, SI_KERNEL, waitmask);
     if (_check_cancel() == -1) return -1;
     if (!restartable || (handler_was_called & SIG_HANDLED_NO_RESTART)) {
       return eintr();

libc/calls/read-nt.c

@@ -31,6 +31,7 @@
 #include "libc/intrin/dll.h"
 #include "libc/intrin/nomultics.internal.h"
 #include "libc/intrin/strace.internal.h"
+#include "libc/intrin/weaken.h"
 #include "libc/macros.internal.h"
 #include "libc/nt/console.h"
 #include "libc/nt/createfile.h"
@@ -721,7 +722,9 @@ static textwindows int WaitForConsole(struct Fd *f, sigset_t waitmask) {
   }
   if (_check_cancel() == -1) return -1;
   if (f->flags & _O_NONBLOCK) return eagain();
-  if ((sig = __sig_get(waitmask))) goto DeliverSignal;
+  if (_weaken(__sig_get) && (sig = _weaken(__sig_get)(waitmask))) {
+    goto DeliverSignal;
+  }
   struct PosixThread *pt = _pthread_self();
   pt->pt_blkmask = waitmask;
   pt->pt_semaphore = sem = CreateSemaphore(0, 0, 1, 0);
@@ -732,11 +735,13 @@ static textwindows int WaitForConsole(struct Fd *f, sigset_t waitmask) {
   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();
-DeliverSignal:
-  int handler_was_called = __sig_relay(sig, SI_KERNEL, waitmask);
-  if (_check_cancel() == -1) return -1;
-  if (!(handler_was_called & SIG_HANDLED_NO_RESTART)) return -2;
+  if (_weaken(__sig_get)) {
+    if (!(sig = _weaken(__sig_get)(waitmask))) return eintr();
+  DeliverSignal:
+    int handler_was_called = _weaken(__sig_relay)(sig, SI_KERNEL, waitmask);
+    if (_check_cancel() == -1) return -1;
+    if (!(handler_was_called & SIG_HANDLED_NO_RESTART)) return -2;
+  }
   return eintr();
 }
 

libc/calls/readwrite-nt.c

@@ -22,6 +22,7 @@
 #include "libc/calls/struct/fd.internal.h"
 #include "libc/calls/struct/sigset.h"
 #include "libc/calls/syscall_support-nt.internal.h"
+#include "libc/intrin/weaken.h"
 #include "libc/nt/enum/filetype.h"
 #include "libc/nt/errors.h"
 #include "libc/nt/events.h"
@@ -82,7 +83,9 @@ RestartOperation:
   bool eagained = false;
   // check for signals and cancelation
   if (_check_cancel() == -1) return -1;  // ECANCELED
-  if ((sig = __sig_get(waitmask))) goto HandleInterrupt;
+  if (_weaken(__sig_get) && (sig = _weaken(__sig_get)(waitmask))) {
+    goto HandleInterrupt;
+  }
 
   // signals have already been fully blocked by caller
   // perform i/o operation with atomic signal/cancel checking
@@ -130,9 +133,9 @@ RestartOperation:
       return eagain();
     }
     // otherwise it must be due to a kill() via __sig_cancel()
-    if ((sig = __sig_get(waitmask))) {
+    if (_weaken(__sig_relay) && (sig = _weaken(__sig_get)(waitmask))) {
     HandleInterrupt:
-      int handler_was_called = __sig_relay(sig, SI_KERNEL, waitmask);
+      int handler_was_called = _weaken(__sig_relay)(sig, SI_KERNEL, waitmask);
       if (_check_cancel() == -1) return -1;  // possible if we SIGTHR'd
       // read() is @restartable unless non-SA_RESTART hands were called
       if (!(handler_was_called & SIG_HANDLED_NO_RESTART)) {

libc/calls/sig.c

@@ -218,10 +218,12 @@ textwindows int __sig_raise(volatile int sig, int sic) {
 }
 
 textwindows int __sig_relay(int sig, int sic, sigset_t waitmask) {
+  sigset_t m;
   int handler_was_called;
-  sigset_t m = __sig_begin(waitmask);
+  m = atomic_exchange_explicit(&__get_tls()->tib_sigmask, waitmask,
+                               memory_order_acquire);
   handler_was_called = __sig_raise(sig, SI_KERNEL);
-  __sig_finish(m);
+  atomic_store_explicit(&__get_tls()->tib_sigmask, m, memory_order_release);
   return handler_was_called;
 }
 

libc/calls/struct/sigset.internal.h

@@ -15,9 +15,7 @@ COSMOPOLITAN_C_START_
   while (0)
 
 sigset_t __sig_block(void);
-void __sig_finish(sigset_t);
 void __sig_unblock(sigset_t);
-sigset_t __sig_begin(sigset_t);
 int __sys_sigprocmask(int, const uint64_t *, uint64_t *, uint64_t);
 int sys_sigprocmask(int, const sigset_t *, sigset_t *);
 int sys_sigsuspend(const uint64_t *, uint64_t);

libc/intrin/sig.c

@@ -47,12 +47,3 @@ void __sig_unblock(sigset_t m) {
     sys_sigprocmask(SIG_SETMASK, &m, 0);
   }
 }
-
-textwindows sigset_t __sig_begin(sigset_t waitmask) {
-  return atomic_exchange_explicit(&__get_tls()->tib_sigmask, waitmask,
-                                  memory_order_acquire);
-}
-
-textwindows void __sig_finish(sigset_t m) {
-  atomic_store_explicit(&__get_tls()->tib_sigmask, m, memory_order_release);
-}

libc/proc/wait4-nt.c

@@ -22,6 +22,7 @@
 #include "libc/calls/struct/sigset.internal.h"
 #include "libc/intrin/dll.h"
 #include "libc/intrin/strace.internal.h"
+#include "libc/intrin/weaken.h"
 #include "libc/nt/enum/wait.h"
 #include "libc/nt/events.h"
 #include "libc/nt/runtime.h"
@@ -76,8 +77,8 @@ static textwindows int __proc_wait(int pid, int *wstatus, int options,
     if (_check_cancel() == -1) {
       return -1;
     }
-    if ((sig = __sig_get(waitmask))) {
-      handler_was_called = __sig_relay(sig, SI_KERNEL, waitmask);
+    if (_weaken(__sig_get) && (sig = _weaken(__sig_get)(waitmask))) {
+      handler_was_called = _weaken(__sig_relay)(sig, SI_KERNEL, waitmask);
       if (_check_cancel() == -1) {
         return -1;  // ECANCELED because SIGTHR was just handled
       }

libc/sock/winsockblock.c

@@ -20,6 +20,7 @@
 #include "libc/calls/sig.internal.h"
 #include "libc/calls/struct/sigset.h"
 #include "libc/errno.h"
+#include "libc/intrin/weaken.h"
 #include "libc/nt/enum/wait.h"
 #include "libc/nt/errors.h"
 #include "libc/nt/struct/overlapped.h"
@@ -42,7 +43,9 @@ RestartOperation:
   int rc, sig, reason = 0;
   uint32_t status, exchanged;
   if (_check_cancel() == -1) return -1;  // ECANCELED
-  if ((sig = __sig_get(waitmask))) goto HandleInterrupt;
+  if (_weaken(__sig_get) && (sig = _weaken(__sig_get)(waitmask))) {
+    goto HandleInterrupt;
+  }
 
   struct NtOverlapped overlap = {.hEvent = WSACreateEvent()};
   rc = StartSocketOp(handle, &overlap, &flags, arg);
@@ -87,9 +90,9 @@ RestartOperation:
       errno = reason;
       return -1;
     }
-    if ((sig = __sig_get(waitmask))) {
+    if (_weaken(__sig_get) && (sig = _weaken(__sig_get)(waitmask))) {
     HandleInterrupt:
-      int handler_was_called = __sig_relay(sig, SI_KERNEL, waitmask);
+      int handler_was_called = _weaken(__sig_relay)(sig, SI_KERNEL, waitmask);
       if (_check_cancel() == -1) return -1;
       if (handler_was_called != 1) goto RestartOperation;
     }