1  // Copyright 2015 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  #include <signal.h>
       6  #include <stdint.h>
       7  #include <stdio.h>
       8  #include <stdlib.h>
       9  #include <string.h>
      10  
      11  struct sigaction sa;
      12  struct sigaction osa;
      13  
      14  static void (*oldHandler)(int, siginfo_t*, void*);
      15  
      16  static void handler(int signo, siginfo_t* info, void* ctxt) {
      17  	if (oldHandler) {
      18  		oldHandler(signo, info, ctxt);
      19  	}
      20  }
      21  
      22  int install_handler() {
      23  	// Install our own signal handler.
      24  	memset(&sa, 0, sizeof sa);
      25  	sa.sa_sigaction = handler;
      26  	sigemptyset(&sa.sa_mask);
      27  	sa.sa_flags = SA_ONSTACK | SA_SIGINFO;
      28  	memset(&osa, 0, sizeof osa);
      29  	sigemptyset(&osa.sa_mask);
      30  	if (sigaction(SIGSEGV, &sa, &osa) < 0) {
      31  		perror("sigaction");
      32  		return 2;
      33  	}
      34  	if (osa.sa_handler == SIG_DFL) {
      35  		fprintf(stderr, "Go runtime did not install signal handler\n");
      36  		return 2;
      37  	}
      38  	// gccgo does not set SA_ONSTACK for SIGSEGV.
      39  	if (getenv("GCCGO") == NULL && (osa.sa_flags&SA_ONSTACK) == 0) {
      40  		fprintf(stderr, "Go runtime did not install signal handler\n");
      41  		return 2;
      42  	}
      43  	oldHandler = osa.sa_sigaction;
      44  
      45  	return 0;
      46  }
      47  
      48  int check_handler() {
      49  	if (sigaction(SIGSEGV, NULL, &sa) < 0) {
      50  		perror("sigaction check");
      51  		return 2;
      52  	}
      53  	if (sa.sa_sigaction != handler) {
      54  		fprintf(stderr, "ERROR: wrong signal handler: %p != %p\n", sa.sa_sigaction, handler);
      55  		return 2;
      56  	}
      57  	return 0;
      58  }
      59