应用程序段错误堆栈打印

应用程序段错误堆栈打印，嵌入到应用程序，打印同时记录到syslog，方便查看段错误原因
gcc -g -rdynamic -O0 strlen_test.c -o strlen_test

#include <stdio.h>
#include <string.h>
#include <unistd.h>

#include <signal.h>
#include <execinfo.h>
#include <syslog.h>
#include <stdlib.h>

#define SIZE 1024
static void *trap_buffer[SIZE];
static void fault_trap(int n, siginfo_t* msiginfo, void* myact)
{
    int i, num;
    char **calls;

    printf("Fault address:%p\n", msiginfo->si_addr);
    syslog(LOG_USER | LOG_ERR, "DROPSTAT:SIGSEGV-%p \n", msiginfo->si_addr);
    num = backtrace(trap_buffer, SIZE);
    calls = backtrace_symbols(trap_buffer, num);
    for (i = 0; i < num; i++) {
            printf("%s\n", calls[i]);
            syslog(LOG_USER | LOG_ERR, "DROPSTAT:SIGSEGV-%s \n", calls[i]);
    }
    exit(1);
}
static void setup_trap()
{
    struct sigaction act;

    sigemptyset(&act.sa_mask);
    act.sa_flags=SA_SIGINFO;
    act.sa_sigaction=fault_trap;
    sigaction(SIGSEGV,&act,NULL);
}


int main()
{
    //char *p = 100 ;
    char *p = NULL ;
    unsigned long len = 0 ;

    sleep(30);

    setup_trap();

    //len = strlen(p) ; //报错
    *p = 5;

    return 0;
}

===============



/ # ./strlen_test
Fault address:(nil)
./strlen_test() [0x400981]
/lib/libc.so.6() [0x3902833350]
./strlen_test(main+0x30) [0x400a7f]
/lib/libc.so.6(__libc_start_main+0xf1) [0x3902820531]
./strlen_test(_start+0x2a) [0x40085a]
/ #

sh-4.4# cat var/log/syslog | tail
2019-09-23T19:55:34.574950+00:00 (none) strlen_test: DROPSTAT:SIGSEGV-(nil)
2019-09-23T19:55:34.575243+00:00 (none) strlen_test: DROPSTAT:SIGSEGV-./strlen_test() [0x400981]
2019-09-23T19:55:34.575279+00:00 (none) strlen_test: DROPSTAT:SIGSEGV-/lib/libc.so.6() [0x3902833350]
2019-09-23T19:55:34.575306+00:00 (none) strlen_test: DROPSTAT:SIGSEGV-./strlen_test(main+0x30) [0x400a7f]
2019-09-23T19:55:34.575334+00:00 (none) strlen_test: DROPSTAT:SIGSEGV-/lib/libc.so.6(__libc_start_main+0xf1) [0x3902820531]
2019-09-23T19:55:34.575359+00:00 (none) strlen_test: DROPSTAT:SIGSEGV-./strlen_test(_start+0x2a) [0x40085a]

其他：
参数解释
If SA_SIGINFO is specified in sa_flags, then sa_sigaction (instead of sa_handler) specifies the signal-handling function for signum.  This
       function  receives  the signal number as its first argument, a pointer to a siginfo_t as its second argument and a pointer to a ucontext_t
       (cast to void *) as its third argument.  (Commonly, the handler function doesn't make any use of the third  argument.   See  getcontext(3)
       for further information about ucontext_t.)