runtime: don't forward SIGPIPE on macOS

macOS and iOS deliver SIGPIPE signals to the main thread and not
the thread that raised it by writing to a closed socket or pipe.

SIGPIPE signals can be suppressed for sockets with the SO_NOSIGPIPE
option, but there is no similar option for pipes. We have no other
choice but to never forward SIGPIPE on macOS.

Fixes #33384

Change-Id: Ice3de75b121f00006ee11c26d560e619536460be
Reviewed-on: https://go-review.googlesource.com/c/go/+/188297
Run-TryBot: Elias Naur <mail@eliasnaur.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

diff --git a/misc/cgo/testcarchive/testdata/main3.c b/misc/cgo/testcarchive/testdata/main3.c
index 60a16cf5fc464ffb13aaf3076694be4a83d7f826..4d11d9ce4c33267cf23f7e63294c1d0bacfc5128 100644 (file)
--- a/misc/cgo/testcarchive/testdata/main3.c
+++ b/misc/cgo/testcarchive/testdata/main3.c
@@ -12,6 +12,7 @@
 #include <time.h>
 #include <sched.h>
 #include <unistd.h>
+#include <pthread.h>
 
 #include "libgo3.h"
 
@@ -51,11 +52,18 @@ static void init() {
        }
 }
 
+static void *provokeSIGPIPE(void *arg) {
+       ProvokeSIGPIPE();
+       return NULL;
+}
+
 int main(int argc, char** argv) {
        int verbose;
        struct sigaction sa;
        int i;
        struct timespec ts;
+       int res;
+       pthread_t tid;
 
        verbose = argc > 2;
        setvbuf(stdout, NULL, _IONBF, 0);
@@ -68,6 +76,19 @@ int main(int argc, char** argv) {
        // a non-default SIGPIPE handler before the runtime initializes.
        ProvokeSIGPIPE();
 
+       // Test that SIGPIPE on a non-main thread is also handled by Go.
+       res = pthread_create(&tid, NULL, provokeSIGPIPE, NULL);
+       if (res != 0) {
+               fprintf(stderr, "pthread_create: %s\n", strerror(res));
+               exit(EXIT_FAILURE);
+       }
+
+       res = pthread_join(tid, NULL);
+       if (res != 0) {
+               fprintf(stderr, "pthread_join: %s\n", strerror(res));
+               exit(EXIT_FAILURE);
+       }
+
        if (verbose) {
                printf("calling sigaction\n");
        }

diff --git a/src/runtime/signal_unix.go b/src/runtime/signal_unix.go
index ad51dc1800fef0746f705994a64dd4082ad61d9b..436c18c1261f5443f829b22a17bbb83cce9386c5 100644 (file)
--- a/src/runtime/signal_unix.go
+++ b/src/runtime/signal_unix.go
@@ -636,6 +636,13 @@ func sigfwdgo(sig uint32, info *siginfo, ctx unsafe.Pointer) bool {
                return true
        }
 
+       // This function and its caller sigtrampgo assumes SIGPIPE is delivered on the
+       // originating thread. This property does not hold on macOS (golang.org/issue/33384),
+       // so we have no choice but to ignore SIGPIPE.
+       if GOOS == "darwin" && sig == _SIGPIPE {
+               return true
+       }
+
        // If there is no handler to forward to, no need to forward.
        if fwdFn == _SIG_DFL {
                return false