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/* Test 70 - regression test for m_out vfs race condition.
*
* Regression test for vfs overwriting m_out fields by competing threads.
* lseek() uses one of these fields too so this test performs concurrent
* lseek()s to trigger this situation.
*
* The program consists of 2 processes, each seeking to different ranges in
* a test file. The bug would return the wrong value in one of the messaeg
* fields so the lseek() return value would be wrong sometimes.
*
* The first instance seeks from 0 to SEEKWINDOW, the other instance seeks
* from SEEKWINDOW to SEEKWINDOW+SEEKWINDOW.
*/
#include <time.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include "common.h"
#define SEEKWINDOW 1000
static int
doseeks(int seekbase)
{
char template[30] = "tempfile.XXXXXXXX";
int iteration, fd = mkstemp(template);
int limit = seekbase + SEEKWINDOW;
/* make a temporary file, unlink it so it's always gone
* afterwards, and make it the size we need.
*/
if(fd < 0) { perror("mkstemp"); e(2); return 1; }
if(unlink(template) < 0) { perror("unlink"); e(3); return 1; }
if(ftruncate(fd, limit) < 0) { perror("ftruncate"); e(4); return 1; }
/* try lseek() lots of times with different arguments and make
* sure we get the right return value back, while this happens
* in a concurrent process too.
*/
#define ITERATIONS 5000
for(iteration = 0; iteration < ITERATIONS; iteration++) {
int o;
for(o = seekbase; o < limit; o++) {
int r;
if((r=lseek(fd, o, SEEK_SET)) != o) {
if(r < 0) perror("lseek");
fprintf(stderr, "%d/%d %d != %d\n",
iteration, ITERATIONS, r, o);
e(5);
return 1;
}
}
}
return 0;
}
int
main(void)
{
start(70);
pid_t f;
int result;
if((f=fork()) < 0) { e(1); quit(); }
if(f == 0) { exit(doseeks(0)); }
if(doseeks(SEEKWINDOW)) { e(10); }
if (waitpid(f, &result, 0) == -1) e(11);
if (WEXITSTATUS(result) != 0) e(12);
quit();
return(-1); /* impossible */
}
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