libgo/misc/cgo/test/issue9400_linux.go

   1 // Copyright 2014 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // Test that SIGSETXID runs on signal stack, since it's likely to
   6 // overflow if it runs on the Go stack.
   7
   8 package cgotest
   9
  10 /*
  11 #include <sys/types.h>
  12 #include <unistd.h>
  13 */
  14 import "C"
  15
  16 import (
  17         "runtime"
  18         "sync/atomic"
  19         "testing"
  20
  21         "./issue9400"
  22 )
  23
  24 func test9400(t *testing.T) {
  25         // We synchronize through a shared variable, so we need two procs
  26         defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(2))
  27
  28         // Start signaller
  29         atomic.StoreInt32(&issue9400.Baton, 0)
  30         go func() {
  31                 // Wait for RewindAndSetgid
  32                 for atomic.LoadInt32(&issue9400.Baton) == 0 {
  33                         runtime.Gosched()
  34                 }
  35                 // Broadcast SIGSETXID
  36                 runtime.LockOSThread()
  37                 C.setgid(0)
  38                 // Indicate that signalling is done
  39                 atomic.StoreInt32(&issue9400.Baton, 0)
  40         }()
  41
  42         // Grow the stack and put down a test pattern
  43         const pattern = 0x123456789abcdef
  44         var big [1024]uint64 // len must match assmebly
  45         for i := range big {
  46                 big[i] = pattern
  47         }
  48
  49         // Temporarily rewind the stack and trigger SIGSETXID
  50         issue9400.RewindAndSetgid()
  51
  52         // Check test pattern
  53         for i := range big {
  54                 if big[i] != pattern {
  55                         t.Fatalf("entry %d of test pattern is wrong; %#x != %#x", i, big[i], uint64(pattern))
  56                 }
  57         }
  58 }