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/*
 * This application tests the behavior when a signal is delivered on a
 * bad application stack or when a signal handler returns from a bad
 * application stack.  In both cases, Pin (or the kernel) tries to
 * read or write a signal context frame from inaccessible memory, and
 * this causes an error.
 *
 * This application tests several variants if this situation.  See the
 * comments in the makefile, which describe each variant that is tested.
 */

// features.h does not exist on FreeBSD
#ifdef TARGET_LINUX
// features initializes the system's state, including the state of __USE_GNU
#include <features.h>
#endif

// If __USE_GNU is defined, we don't need to do anything.
// If we defined it ourselves, we need to undefine it later.
#ifndef __USE_GNU
    #define __USE_GNU
    #define APP_UNDEF_USE_GNU
#endif

#if defined(TARGET_MAC)
#include <sys/ucontext.h>
#elif defined(TARGET_ANDROID)
#include "android_ucontext.h"
#else
#include <ucontext.h>
#endif

// If we defined __USE_GNU ourselves, we need to undefine it here.
#ifdef APP_UNDEF_USE_GNU
    #undef __USE_GNU
    #undef APP_UNDEF_USE_GNU
#endif


#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <errno.h>
#include <string.h>


static void Usage();
static void Handle(int, siginfo_t *, void *);
extern void DoILLOnBadStack();
extern int DoSigreturnOnBadStack();

int DoSigill = 0;
int DoAltStack = 0;


int main(int argc, char **argv)
{
    struct sigaction act;
    stack_t ss;


    if (argc != 3)
    {
        Usage();
        return 1;
    }
    if (strcmp(argv[1], "sigill") == 0)
    {
        DoSigill = 1;
    }
    else if (strcmp(argv[1], "sigreturn") == 0)
    {
        DoSigill = 0;
    }
    else
    {
        Usage();
        return 1;
    }
    if (strcmp(argv[2], "altstack") == 0)
    {
        DoAltStack = 1;
    }
    else if (strcmp(argv[2], "noaltstack") == 0)
    {
        DoAltStack = 0;
    }
    else
    {
        Usage();
        return 1;
    }

    if (DoAltStack)
    {
        ss.ss_sp = malloc(SIGSTKSZ);
        ss.ss_flags = 0;
        ss.ss_size = SIGSTKSZ;
        if (sigaltstack(&ss, 0) != 0)
        {
            printf("Failed to set alternate stack\n");
            return 1;
        }
    }

    act.sa_sigaction = Handle;
    act.sa_flags = (DoAltStack) ? (SA_ONSTACK | SA_SIGINFO) : (SA_SIGINFO);
    sigemptyset(&act.sa_mask);
    if (sigaction(SIGSEGV, &act, 0) != 0)
    {
        printf("Unable to set SEGV handler\n");
        return 1;
    }

    if (DoSigill)
    {
        act.sa_sigaction = Handle;
#if defined(TARGET_MAC)
        act.sa_flags = (DoAltStack) ? (SA_ONSTACK | SA_SIGINFO) : (SA_SIGINFO);
#else
        act.sa_flags = SA_SIGINFO;
#endif
        sigemptyset(&act.sa_mask);
        if (sigaction(SIGILL, &act, 0) != 0)
        {
            printf("Unable to set ILL handler\n");
            return 1;
        }

        DoILLOnBadStack();
    }
    else
    {
        int err = DoSigreturnOnBadStack();
        switch (err)
        {
        case EFAULT:
            printf("Sigreturn returned EFAULT\n");
            break;
        default:
            printf("Sigreturn returned <error %d>\n", err);
            break;
        }
    }

    printf("Returning normally\n");
    return 0;
}


static void Usage()
{
    printf("Usage: bad-stack {sigill | sigreturn} {altstack | noaltstack}\n");
}


static void Handle(int sig, siginfo_t *info, void *v)
{
    ucontext_t *ctxt = v;

    switch (sig)
    {
    case SIGSEGV:
        printf("Got signal SEGV\n");
        break;
    case SIGILL:
        printf("Got signal ILL\n");
        break;
    default:
        printf("Got signal <%d>\n", sig);
        break;
    }

    if (DoSigill)
    {
        /*
         * Skip over the UD2 instruction.
         */
#if defined(TARGET_LINUX) && defined(TARGET_IA32)
        ctxt->uc_mcontext.gregs[REG_EIP] += 2;
#elif defined(TARGET_LINUX) && defined(TARGET_IA32E)
        ctxt->uc_mcontext.gregs[REG_RIP] += 2;
#elif defined(TARGET_BSD) && defined(TARGET_IA32)
        ctxt->uc_mcontext.mc_eip += 2;
#elif defined(TARGET_BSD) && defined(TARGET_IA32E)
        ctxt->uc_mcontext.mc_rip += 2;
#elif defined(TARGET_MAC) && defined(TARGET_IA32)
        ctxt->uc_mcontext->__ss.__eip += 2;
#elif defined(TARGET_MAC) && defined(TARGET_IA32E)
        ctxt->uc_mcontext->__ss.__rip += 2;
#else
#error "Undefined code"
#endif
    }
    else
    {
        exit(0);
    }
}
