From 7edd4c1885f4ecc31b80f157f7aa96ccd40d1075 Mon Sep 17 00:00:00 2001 From: Ian Lance Taylor Date: Mon, 2 Jul 2018 16:28:43 +0000 Subject: re PR go/86331 (the gccgo's "go" tool looks like failing to invoke any sub go command) PR go/86331 os: check return value as well as error from waitid https://gcc.gnu.org/PR86331 indicates that if a signal handler runs it is possible for syscall.Syscall6 to return a non-zero errno value even if no error occurs. That is a problem in general, but this fix will let us work around the general problem for the specific case of calling waitid. Reviewed-on: https://go-review.googlesource.com/121595 From-SVN: r262313 --- libgo/go/os/wait_waitid.go | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'libgo/go/os') diff --git a/libgo/go/os/wait_waitid.go b/libgo/go/os/wait_waitid.go index 5a62b27..a6284aa 100644 --- a/libgo/go/os/wait_waitid.go +++ b/libgo/go/os/wait_waitid.go @@ -28,9 +28,12 @@ func (p *Process) blockUntilWaitable() (bool, error) { // We don't care about the values it returns. var siginfo [16]uint64 psig := &siginfo[0] - _, _, e := syscall.Syscall6(syscall.SYS_WAITID, _P_PID, uintptr(p.Pid), uintptr(unsafe.Pointer(psig)), syscall.WEXITED|syscall.WNOWAIT, 0, 0) + r, _, e := syscall.Syscall6(syscall.SYS_WAITID, _P_PID, uintptr(p.Pid), uintptr(unsafe.Pointer(psig)), syscall.WEXITED|syscall.WNOWAIT, 0, 0) runtime.KeepAlive(p) - if e != 0 { + // Check r as well as e because syscall.Syscall6 currently + // just returns errno, and the SIGCHLD signal handler may + // change errno. See https://gcc.gnu.org/PR86331. + if r != 0 && e != 0 { // waitid has been available since Linux 2.6.9, but // reportedly is not available in Ubuntu on Windows. // See issue 16610. -- cgit v1.1