sigaltstack() allows a process to define a new alternate signal stack and/or retrieve the state of an existing alternate signal stack.

It can be used when free memory is empty but segment fault is generated

Author: Wang Jiazi

Linux/Signal/signalstack/test.c

@@ -0,0 +1,60 @@
+#define _GNU_SOURCE
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <signal.h>
+ 
+static void sigseg_handler(int sig)
+{
+    int x;
+    printf ("\nCaught signal %d (%s)\n", sig, strsignal(sig));
+    printf ("Top of handler stack near %10p\n", (void *)&x);
+    fflush(NULL);
+ 
+    _exit(123);    //在段错误后不能从此处返回
+}
+ 
+static void overflow_stack(int call_num)
+{
+    char a[1024*1024];        //撑大栈帧
+ 
+    printf ("Call %4d - top of stack near %10p\n", call_num, &a[0]);
+     
+    overflow_stack(call_num + 1);
+}
+ 
+int main(int argc, char *argv[])
+{
+    stack_t sigstack;
+    struct sigaction sa;
+    int j;
+     
+    printf ("Top of standard stack is near %10p\n", (void *)&j);
+ 
+
+#ifdef ALT_STACK
+    //分配可变栈并通知内核
+    sigstack.ss_sp = malloc(SIGSTKSZ);
+    if (sigstack.ss_sp == NULL) {
+       perror ("malloc");
+       exit (EXIT_FAILURE);
+    }
+    sigstack.ss_size = SIGSTKSZ;
+    sigstack.ss_flags = 0;
+    if (sigaltstack(&sigstack, NULL) == -1) {
+       perror ("sigaltstack");
+       exit (EXIT_FAILURE);
+    }
+    printf ("Alternate stack is at    %10p-%p\n", sigstack.ss_sp, (char *)sbrk(0) - 1);
+#endif 
+    sa.sa_handler = sigseg_handler;    //建立SIGSEGV  的处理函数
+    sigemptyset(&sa.sa_mask);
+    sa.sa_flags = SA_ONSTACK;    //处理函数使用可变栈
+    if (sigaction(SIGSEGV, &sa, NULL) == -1) {
+       perror("sigaction");
+       exit(125);
+    }
+ 
+    overflow_stack(1);
+}