p8-13.c

SUN Solaris8平台下进程间通信

#include <stdio.h>
#include <signal.h>
#define M 1000
int n = 0;
void set_ss_stack(stack_t *, stack_t *);
void check_ss_flags(char *);
int make_stack_overflow(void);
void sig_segv(int);
void sig_usr1(int);
void error_exit(char *);
void main(void)
{
    struct sigaction act;
    stack_t sigstk,ostk;
     /* 安装信号句柄并在替代信号栈上运行它们 */
    act.sa_flags = 0;
    act.sa_flags |= SA_ONSTACK;         
    sigemptyset(&act.sa_mask);
    act.sa_handler = sig_segv;
    if (sigaction(SIGSEGV,&act,NULL) <0 )
        perror("SIGSEGV error");
    act.sa_handler = sig_usr1;
    if (sigaction(SIGUSR1,&act,NULL) < 0)
        perror("SIGUSR1 error");
    set_ss_stack(&sigstk, &ostk);   /* 设置替代信号栈 */
    check_ss_flags("before kill in main");  /* 查看替代信号栈 */
    kill(getpid(), SIGUSR1);    /* 给自己发送SIGUSR1信号 */  
    check_ss_flags("after kill in main");         
    make_stack_overflow();  /* 造成栈空间溢出 */ 
    return;
}
/* 设置替代信号栈 */
void set_ss_stack(stack_t *stk, stack_t *ostk)
{
     if ((stk->ss_sp = (char *)malloc(SIGSTKSZ)) == NULL) /* 为替代信号栈分配空间 */
        perror("   malloc error");
    stk->ss_size = SIGSTKSZ; 
    stk->ss_flags = 0;
    if (sigaltstack(stk, ostk) < 0)
        perror("   sigaltstack fail");
    return;
}
/* 查看替代信号栈状态 */
void check_ss_flags(char *str)  
{
    stack_t ostk;
    printf("%s\n",str);
    if (sigaltstack(NULL, &ostk) < 0)
        perror(" sigaltstack exam fail.");
    if (ostk.ss_flags&SS_ONSTACK)
        printf("   flags=SS_ONSTACK \n");
    else if(ostk.ss_flags&SS_DISABLE)
        printf("   flags=SS_DISABLE \n");
    else 
        printf("   flags=%d\n",ostk.ss_flags);
    return;
}
int make_stack_overflow(void)
{
    int a[100000];
    a[100000-1] = make_stack_overflow();    /* 递归调用直至栈溢出 */
    return n++;
}
void sig_segv(int signo)            /* SIGSEGV信号句柄 */
{
    int b[M];
    stack_t sigstk,ostk;
    check_ss_flags("in sig_segv:");
    b[M-1] = signo;
    printf("We catched SIGSEGV signal! \n");
    exit(0);
}
void sig_usr1(int signo)            /* SIGUSR1信号句柄 */
{
    stack_t sigstk,ostk;
    check_ss_flags("in sig_usr1:");
    set_ss_stack(&sigstk, &ostk);      /* 设置替代信号栈,这一次将失败 */
    return;
}