Revert "runtime: handle SIGPIPE in c-archive and c-shared programs"

This reverts commit d24b57a6.

Reason for revert: Further complications arised (issue 18100). We'll try again in Go 1.9.

Change-Id: I5ca93d2643a4be877dd9c2d8df3359718440f02f
Reviewed-on: https://go-review.googlesource.com/33770
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
Run-TryBot: Minux Ma <minux@golang.org>

misc/cgo/testcarchive/carchive_test.go

@@ -265,25 +265,6 @@ func TestSignalForwarding(t *testing.T) {
 		t.Logf("%s", out)
 		t.Errorf("got %v; expected SIGSEGV", ee)
 	}
-
-	// Test SIGPIPE forwarding
-	cmd = exec.Command(bin[0], append(bin[1:], "3")...)
-
-	out, err = cmd.CombinedOutput()
-
-	if err == nil {
-		t.Logf("%s", out)
-		t.Error("test program succeeded unexpectedly")
-	} else if ee, ok := err.(*exec.ExitError); !ok {
-		t.Logf("%s", out)
-		t.Errorf("error (%v) has type %T; expected exec.ExitError", err, err)
-	} else if ws, ok := ee.Sys().(syscall.WaitStatus); !ok {
-		t.Logf("%s", out)
-		t.Errorf("error.Sys (%v) has type %T; expected syscall.WaitStatus", ee.Sys(), ee.Sys())
-	} else if !ws.Signaled() || ws.Signal() != syscall.SIGPIPE {
-		t.Logf("%s", out)
-		t.Errorf("got %v; expected SIGPIPE", ee)
-	}
 }
 
 func TestSignalForwardingExternal(t *testing.T) {

misc/cgo/testcarchive/main2.c

@@ -17,7 +17,6 @@
 #include <unistd.h>
 #include <sched.h>
 #include <time.h>
-#include <errno.h>
 
 #include "libgo2.h"
 
@@ -27,7 +26,6 @@ static void die(const char* msg) {
 }
 
 static volatile sig_atomic_t sigioSeen;
-static volatile sig_atomic_t sigpipeSeen;
 
 // Use up some stack space.
 static void recur(int i, char *p) {
@@ -39,11 +37,6 @@ static void recur(int i, char *p) {
 	}
 }
 
-// Signal handler that uses up more stack space than a goroutine will have.
-static void pipeHandler(int signo, siginfo_t* info, void* ctxt) {
-	sigpipeSeen = 1;
-}
-
 // Signal handler that uses up more stack space than a goroutine will have.
 static void ioHandler(int signo, siginfo_t* info, void* ctxt) {
 	char a[1024];
@@ -113,10 +106,6 @@ static void init() {
 		die("sigaction");
 	}
 
-	sa.sa_sigaction = pipeHandler;
-	if (sigaction(SIGPIPE, &sa, NULL) < 0) {
-		die("sigaction");
-	}
 }
 
 int main(int argc, char** argv) {
@@ -178,30 +167,7 @@ int main(int argc, char** argv) {
 		nanosleep(&ts, NULL);
 		i++;
 		if (i > 5000) {
-			fprintf(stderr, "looping too long waiting for SIGIO\n");
-			exit(EXIT_FAILURE);
-		}
-	}
-
-	if (verbose) {
-		printf("provoking SIGPIPE\n");
-	}
-
-	GoRaiseSIGPIPE();
-
-	if (verbose) {
-		printf("waiting for sigpipeSeen\n");
-	}
-
-	// Wait until the signal has been delivered.
-	i = 0;
-	while (!sigpipeSeen) {
-		ts.tv_sec = 0;
-		ts.tv_nsec = 1000000;
-		nanosleep(&ts, NULL);
-		i++;
-		if (i > 1000) {
-			fprintf(stderr, "looping too long waiting for SIGPIPE\n");
+			fprintf(stderr, "looping too long waiting for signal\n");
 			exit(EXIT_FAILURE);
 		}
 	}

misc/cgo/testcarchive/main3.c

@@ -34,13 +34,6 @@ int main(int argc, char** argv) {
 	verbose = argc > 2;
 	setvbuf(stdout, NULL, _IONBF, 0);
 
-	if (verbose) {
-		printf("raising SIGPIPE\n");
-	}
-
-	// Test that the Go runtime handles SIGPIPE.
-	ProvokeSIGPIPE();
-
 	if (verbose) {
 		printf("calling sigaction\n");
 	}

misc/cgo/testcarchive/main5.c

@@ -68,24 +68,6 @@ int main(int argc, char** argv) {
 
 			break;
 		}
-		case 3: {
-			if (verbose) {
-				printf("attempting SIGPIPE\n");
-			}
-
-			int fd[2];
-			if (pipe(fd) != 0) {
-				printf("pipe(2) failed\n");
-				return 0;
-			}
-			// Close the reading end.
-			close(fd[0]);
-			// Expect that write(2) fails (EPIPE)
-			if (write(fd[1], "some data", 9) != -1) {
-				printf("write(2) unexpectedly succeeded\n");
-				return 0;
-			}
-		}
 		default:
 			printf("Unknown test: %d\n", test);
 			return 0;

misc/cgo/testcarchive/src/libgo2/libgo2.go

@@ -4,30 +4,6 @@
 
 package main
 
-/*
-#include <signal.h>
-#include <unistd.h>
-#include <stdlib.h>
-#include <stdio.h>
-
-// Raise SIGPIPE.
-static void CRaiseSIGPIPE() {
-	int fds[2];
-
-	if (pipe(fds) == -1) {
-		perror("pipe");
-		exit(EXIT_FAILURE);
-	}
-	// Close the reader end
-	close(fds[0]);
-	// Write to the writer end to provoke a SIGPIPE
-	if (write(fds[1], "some data", 9) != -1) {
-		fprintf(stderr, "write to a closed pipe succeeded\n");
-		exit(EXIT_FAILURE);
-	}
-	close(fds[1]);
-}
-*/
 import "C"
 
 import (
@@ -70,11 +46,5 @@ func TestSEGV() {
 func Noop() {
 }
 
-// Raise SIGPIPE.
-//export GoRaiseSIGPIPE
-func GoRaiseSIGPIPE() {
-	C.CRaiseSIGPIPE()
-}
-
 func main() {
 }

misc/cgo/testcarchive/src/libgo3/libgo3.go

@@ -40,17 +40,5 @@ func SawSIGIO() C.int {
 	}
 }
 
-// ProvokeSIGPIPE provokes a kernel-initiated SIGPIPE
-//export ProvokeSIGPIPE
-func ProvokeSIGPIPE() {
-	r, w, err := os.Pipe()
-	if err != nil {
-		panic(err)
-	}
-	r.Close()
-	defer w.Close()
-	w.Write([]byte("some data"))
-}
-
 func main() {
 }

src/os/signal/doc.go

@@ -181,11 +181,10 @@ If the Go runtime sees an existing signal handler for the SIGCANCEL or
 SIGSETXID signals (which are used only on GNU/Linux), it will turn on
 the SA_ONSTACK flag and otherwise keep the signal handler.
 
-For the synchronous signals and SIGPIPE, the Go runtime will install a
-signal handler. It will save any existing signal handler. If a
-synchronous signal arrives while executing non-Go code, the Go runtime
-will invoke the existing signal handler instead of the Go signal
-handler.
+For the synchronous signals, the Go runtime will install a signal
+handler. It will save any existing signal handler. If a synchronous
+signal arrives while executing non-Go code, the Go runtime will invoke
+the existing signal handler instead of the Go signal handler.
 
 Go code built with -buildmode=c-archive or -buildmode=c-shared will
 not install any other signal handlers by default. If there is an

src/runtime/signal_unix.go

@@ -111,8 +111,8 @@ func sigInstallGoHandler(sig uint32) bool {
 	}
 
 	// When built using c-archive or c-shared, only install signal
-	// handlers for synchronous signals and SIGPIPE.
-	if (isarchive || islibrary) && t.flags&_SigPanic == 0 && sig != _SIGPIPE {
+	// handlers for synchronous signals.
+	if (isarchive || islibrary) && t.flags&_SigPanic == 0 {
 		return false
 	}
 
@@ -497,15 +497,9 @@ func sigfwdgo(sig uint32, info *siginfo, ctx unsafe.Pointer) bool {
 		return true
 	}
 
+	// Only forward synchronous signals.
 	c := &sigctxt{info, ctx}
-	// Only forward signals from the kernel.
-	// On Linux and Darwin there is no way to distinguish a SIGPIPE raised by a write
-	// to a closed socket or pipe from a SIGPIPE raised by kill or pthread_kill
-	// so we'll treat every SIGPIPE as kernel-generated.
-	userSig := c.sigcode() == _SI_USER &&
-		(sig != _SIGPIPE || GOOS != "linux" && GOOS != "android" && GOOS != "darwin")
-	// Only forward synchronous signals and SIGPIPE.
-	if userSig || flags&_SigPanic == 0 && sig != _SIGPIPE {
+	if c.sigcode() == _SI_USER || flags&_SigPanic == 0 {
 		return false
 	}
 	// Determine if the signal occurred inside Go code. We test that: