85 lines
2 KiB
C
85 lines
2 KiB
C
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/* Test 70 - regression test for m_out vfs race condition.
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*
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* Regression test for vfs overwriting m_out fields by competing threads.
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* lseek() uses one of these fields too so this test performs concurrent
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* lseek()s to trigger this situation.
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*
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* The program consists of 2 processes, each seeking to different ranges in
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* a test file. The bug would return the wrong value in one of the messaeg
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* fields so the lseek() return value would be wrong sometimes.
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*
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* The first instance seeks from 0 to SEEKWINDOW, the other instance seeks
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* from SEEKWINDOW to SEEKWINDOW+SEEKWINDOW.
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*/
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#include <time.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <stdio.h>
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#include "common.h"
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#define SEEKWINDOW 1000
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static int
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doseeks(int seekbase)
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{
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char template[30] = "tempfile.XXXXXXXX";
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int iteration, fd = mkstemp(template);
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int limit = seekbase + SEEKWINDOW;
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/* make a temporary file, unlink it so it's always gone
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* afterwards, and make it the size we need.
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*/
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if(fd < 0) { perror("mkstemp"); e(2); return 1; }
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if(unlink(template) < 0) { perror("unlink"); e(3); return 1; }
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if(ftruncate(fd, limit) < 0) { perror("ftruncate"); e(4); return 1; }
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/* try lseek() lots of times with different arguments and make
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* sure we get the right return value back, while this happens
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* in a concurrent process too.
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*/
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#define ITERATIONS 50000
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for(iteration = 0; iteration < ITERATIONS; iteration++) {
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int o;
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for(o = seekbase; o < limit; o++) {
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int r;
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if((r=lseek(fd, o, SEEK_SET)) != o) {
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if(r < 0) perror("lseek");
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fprintf(stderr, "%d/%d %d != %d\n",
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iteration, ITERATIONS, r, o);
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e(5);
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return 1;
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}
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}
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}
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return 0;
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}
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int
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main()
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{
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start(70);
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pid_t f;
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int result;
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if((f=fork()) < 0) { e(1); quit(); }
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if(f == 0) { exit(doseeks(0)); }
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if(doseeks(SEEKWINDOW)) { e(10); }
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if (waitpid(f, &result, 0) == -1) e(11);
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if (WEXITSTATUS(result) != 0) e(12);
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quit();
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return(-1); /* impossible */
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}
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