a strange segment fault about ltp-posix test

yanglei_fage · #1 (**permalink**) 06-24-2009

Hi all

In the ltp-posix test,there is a case in open_posix_testsuite\conformance\interfaces\timer_gettime\speculative/6-1.c

Quote:

#include <time.h>
#include <stdio.h>
#include <errno.h>
//#include "posixtest.h"
#define BOGUSTID 9999
int main(int argc, char *argv[])
{
timer_t tid;
struct itimerspec its;
tid = (timer_t) BOGUSTID;

if (timer_gettime(tid, &its) == -1) {
if (EINVAL == errno) {
printf("fcn returned -1 and errno==EINVAL\n");
//return PTS_PASS;
} else {
printf("fcn returned -1 but errno!=EINVAL\n");
printf("Test FAILED\n");
//return PTS_FAIL;
}
}
printf("fcn did not return -1\n");
//return PTS_PASS;
}

I run the above code,it will has a segment fault, if I modify it to below,it works well

Quote:

#include <time.h>
#include <stdio.h>
#include <errno.h>
//#include "posixtest.h"
#define BOGUSTID 9999
int main(int argc, char *argv[])
{
timer_t tid;
struct itimerspec its;
int tval=BOGUSTID;
printf("%d\n",tval);
tid = (timer_t) &tval;
printf("%d\n",tid);
if (timer_gettime(tid, &its) == -1) {
if (EINVAL == errno) {
printf("fcn returned -1 and errno==EINVAL\n");
//return PTS_PASS;
} else {
printf("fcn returned -1 but errno!=EINVAL\n");
printf("Test FAILED\n");
//return PTS_FAIL;
}
}
printf("fcn did not return -1\n");
// return PTS_PASS;
}

Anybody can tell me why?

fpmurphy · #2 (**permalink**) 06-24-2009

Reducing the problem to its essence makes it easier to understand

Code:

#include <time.h>
#define BOGUSTID 9999

timer_t tid;
  
#if WANT_SEG_FAULT
   tid = (timer_t) BOGUSTID
#else
   int tval=BOGUSTID;
   tid = (timer_t) &tval;
#endif

The correct header is being included but an assumption is being made that tid is capable of storing a value as shown above. Generally this assumption is wrong as timer_t is specified to be an opaque type in POSIX.1. On most versions of GNU/Linux, timer_t is actually defined by

Code:

#define timer_t   void *

In your example you are trying to stuff 9999 into a void * - which is not on.

BTW, your workaround is defective also. tid is not being set to 9999 but to the address of tval.

More UNIX and Linux Forum Topics You Might Find Helpful
Thread	Thread Starter	Forum	Replies	Last Post
code segment	trob	UNIX for Dummies Questions & Answers	1	04-23-2009 08:33 PM
test command looks strange...	jjinno	Shell Programming and Scripting	2	11-02-2007 07:31 PM
extract segment	mpang_	Shell Programming and Scripting	1	01-12-2007 01:33 AM
Strange error message with regex test...	fgilain	Shell Programming and Scripting	4	05-31-2006 09:52 PM
Segment Fault	zhshqzyc	High Level Programming	9	04-07-2006 11:47 AM

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes	Rate This Thread
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode	Rate This Thread: