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/*
* $OpenBSD: sigret.c,v 1.5 2003/07/31 21:48:04 deraadt Exp $
*
* Public Domain
*
* Playing games with sigreturn. Check if calling sigreturn from a
* signal handler screws anything up.
*
* Run with:
* -a: use an alternate signal stack
*
* -b: call sigreturn from outside of a signal handler
* An error is OK
*
* -c: clobber the sigcontext before calling sigreturn
* the program should die
*
* -f: don't use sigreturn -- fall through the signal handler
* -c, and -i options ignored when used
*
* -i: call sigreturn from a function called by the signal handler
*
*/
#include <sys/time.h>
#include <err.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
/*
* sigalarm occurs 50 times/second. Stop running after 10 seconds
* (100 interrupts).
*/
#define MAX_INTERRUPTS 500
int failed;
int altstack;
int badcall;
int clobbercall;
int fallthru;
int indirect;
volatile int count;
struct sigcontext gscp;
int gscp_loaded;
static void
usage(const char * err, ...)
{
extern const char * __progname;
if (err) {
va_list ap;
va_start(ap, err);
vwarnx(err, ap);
va_end(ap);
}
fprintf(stderr, "usage: %s [-abcfi]\n", __progname);
exit(1);
}
static void
indirect_return(struct sigcontext * scp)
{
sigreturn(scp);
}
static void
sig_handler(int sig, siginfo_t *blah, void *x)
{
struct sigcontext * scp = x;
count++;
if (!fallthru) {
if (clobbercall)
memset(scp, 0, sizeof *scp);
if (indirect)
indirect_return(scp);
else if (badcall) {
gscp = *scp;
gscp_loaded = 1;
} else
sigreturn(scp);
}
}
static void
test2(char *fmt)
{
char *ofmt = fmt;
if (gscp_loaded) {
gscp_loaded = 0;
sigreturn(&gscp);
}
for (; *fmt; fmt++)
switch (*fmt) {
case 'i':
case 'c':
case 'l':
case 'p':
break;
default:
failed = 1;
fprintf(stderr,
"unexpected character 0x%02x `%c' in %s: count %d\n",
*fmt, *fmt, ofmt, count);
}
}
int
main(int argc, char * argv[])
{
extern char *optarg;
extern int optind;
int opt;
struct sigaction act;
struct sigaltstack ss;
while ((opt = getopt(argc, argv, "abcfi")) != -1) {
switch (opt) {
case 'a':
/* use sigaltstack */
altstack = 1;
break;
case 'b':
/* call outside of sig_handler */
badcall = 1;
break;
case 'c':
/* force error by munging sigcontext */
clobbercall = 1;
break;
case 'f':
/* don't use sigreturn */
fallthru = 1;
break;
case 'i':
/* call sigreturn indirectly */
indirect = 1;
break;
}
}
/* make sure there is no other cruft left on the command line */
if (optind != argc)
usage("unknown argument -- %s", argv[ optind ]);
if (altstack) {
if ((ss.ss_sp = malloc(SIGSTKSZ)) == NULL)
errx(1, "ss_sp malloc");
ss.ss_size = SIGSTKSZ;
ss.ss_flags = 0;
if (sigaltstack(&ss,0) == -1)
err(1, "sigaltstack");
}
sigfillset(&act.sa_mask);
act.sa_sigaction = sig_handler;
act.sa_flags = SA_RESTART;
if (altstack)
act.sa_flags |= SA_ONSTACK;
sigaction(SIGALRM, &act, NULL);
ualarm(10000, 10000);
while (count < MAX_INTERRUPTS)
test2("iclp");
return failed;
}
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