signal handling issue.

[Alex Davis]

There appears to be a change between linux 2.4 and 2.6
in how signals are handled. As a test, I wrote the program
below:

#include <stdio.h>
#include <signal.h>
#include <setjmp.h>

static jmp_buf env;

static void handler(int s) {
        printf("caught signal %d\n", s);
        longjmp(env, 1);
}

int main() {
        int * p = 0;

        printf("write\n");
        signal(SIGSEGV, handler);
        if ( ! setjmp(env) )
        {
                *p = 0;
        }

        printf("read\n");
        signal(SIGSEGV, handler);
        if ( ! setjmp(env) )
        {
                int a = *p;
        }
        return 0;
}

When run on 2.4.26, the program prints:

write
caught signal 11
read
caught signal 11


Which (I think) is expected, but when run on 2.6.5,
the program prints:

write
caught signal 11
read
Segmentation fault

It's as if the second call to signal is being ignored.
Is this a bug or a feature?

-Alex



=====
I code, therefore I am


	
		
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