minix/test/t40f.c

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/* t40f.c
*
* Test timing
*
* Select works on regular files, (pseudo) terminal devices, streams-based
* files, FIFOs, pipes, and sockets. This test verifies selecting with a time
* out set.
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/select.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <time.h>
#include <errno.h>
#include <string.h>
#include <signal.h>
#include "common.h"
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#define DO_HANDLEDATA 1
#define DO_PAUSE 3
#define DO_TIMEOUT 7
#define DO_DELTA 0.5
#define MAX_ERROR 5
#define DELTA(x,y) (x.tv_sec - y.tv_sec) * system_hz \
+ (x.tv_usec - y.tv_usec) * system_hz / 1000000
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int got_signal = 0;
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int fd_ap[2];
int system_hz;
static void catch_signal(int sig_no) {
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got_signal = 1;
}
static float compute_diff(struct timeval start, struct timeval end, float compare) {
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/* Compute time difference. It is assumed that the value of start <= end. */
clock_t delta;
int seconds, hundreths;
float diff;
delta = DELTA(end, start); /* delta is in ticks */
seconds = (int) (delta / system_hz);
hundreths = (int) (delta * 100 / system_hz) - (seconds * 100);
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diff = seconds + (hundreths / 100.0);
diff -= compare;
if(diff < 0) diff *= -1; /* Make diff a positive value */
return diff;
}
static void do_child(void) {
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struct timeval tv;
/* Let the parent do initial read and write tests from and to the pipe. */
tv.tv_sec = DO_PAUSE + DO_PAUSE + DO_PAUSE + 1;
tv.tv_usec = 0;
(void) select(0, NULL, NULL, NULL, &tv);
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/* At this point the parent has a pending select with a DO_TIMEOUT timeout.
We're going to interrupt by sending a signal */
if(kill(getppid(), SIGUSR1) < 0) perror("Failed to send signal");
exit(0);
}
static void do_parent(int child) {
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fd_set fds_read;
struct timeval tv, start_time, end_time;
int retval;
/* Install signal handler for SIGUSR1 */
signal(SIGUSR1, catch_signal);
/* Parent and child share an anonymous pipe. Select for read and wait for the
timeout to occur. We wait for DO_PAUSE seconds. Let's see if that's
approximately right.*/
FD_ZERO(&fds_read);
FD_SET(fd_ap[0], &fds_read);
tv.tv_sec = DO_PAUSE;
tv.tv_usec = 0;
(void) gettimeofday(&start_time, NULL); /* Record starting time */
retval = select(fd_ap[0]+1, &fds_read, NULL, NULL, &tv);
(void) gettimeofday(&end_time, NULL); /* Record ending time */
/* Did we time out? */
if(retval != 0) em(1, "Should have timed out");
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/* Approximately right? The standard does not specify how precise the timeout
should be. Instead, the granularity is implementation-defined. In this
test we assume that the difference should be no more than half a second.*/
if(compute_diff(start_time, end_time, DO_PAUSE) > DO_DELTA)
em(2, "Time difference too large");
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/* Let's wait for another DO_PAUSE seconds, expressed as microseconds */
FD_ZERO(&fds_read);
FD_SET(fd_ap[0], &fds_read);
tv.tv_sec = 0;
tv.tv_usec = DO_PAUSE * 1000000L;
(void) gettimeofday(&start_time, NULL); /* Record starting time */
retval = select(fd_ap[0]+1, &fds_read, NULL, NULL, &tv);
(void) gettimeofday(&end_time, NULL); /* Record ending time */
if(retval != 0) em(3, "Should have timed out");
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if(compute_diff(start_time, end_time, DO_PAUSE) > DO_DELTA)
em(4, "Time difference too large");
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/* Let's wait for another DO_PAUSE seconds, expressed in seconds and micro
seconds. */
FD_ZERO(&fds_read);
FD_SET(fd_ap[0], &fds_read);
tv.tv_sec = DO_PAUSE - 1;
tv.tv_usec = (DO_PAUSE - tv.tv_sec) * 1000000L;
(void) gettimeofday(&start_time, NULL); /* Record starting time */
retval = select(fd_ap[0]+1, &fds_read, NULL, NULL, &tv);
(void) gettimeofday(&end_time, NULL); /* Record ending time */
if(retval != 0) em(5, "Should have timed out");
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if(compute_diff(start_time, end_time, DO_PAUSE) > DO_DELTA)
em(6, "Time difference too large");
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/* Finally, we test if our timeout is interrupted by a signal */
FD_ZERO(&fds_read);
FD_SET(fd_ap[0], &fds_read);
tv.tv_sec = DO_TIMEOUT;
tv.tv_usec = 0;
(void) gettimeofday(&start_time, NULL); /* Record starting time */
retval = select(fd_ap[0]+1, &fds_read, NULL, NULL, &tv);
(void) gettimeofday(&end_time, NULL); /* Record ending time */
if(retval != -1) em(7, "Should have been interrupted");
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if(compute_diff(start_time, end_time, DO_TIMEOUT) < DO_DELTA)
em(8, "Failed to get interrupted by a signal");
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if(!got_signal) em(9, "Failed to get interrupted by a signal");
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waitpid(child, &retval, 0);
exit(errct);
}
int main(int argc, char **argv) {
int forkres;
/* Retrieve actual system frequency. */
system_hz = sysconf(_SC_CLK_TCK);
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/* Get subtest number */
if(argc != 2) {
printf("Usage: %s subtest_no\n", argv[0]);
exit(-2);
} else if(sscanf(argv[1], "%d", &subtest) != 1) {
printf("Usage: %s subtest_no\n", argv[0]);
exit(-2);
}
/* Set up anonymous pipe */
if(pipe(fd_ap) < 0) {
perror("Could not create anonymous pipe");
exit(-1);
}
forkres = fork();
if(forkres == 0) do_child();
else if(forkres > 0) do_parent(forkres);
else { /* Fork failed */
perror("Unable to fork");
exit(-1);
}
exit(-2); /* We're not supposed to get here. Both do_* routines should exit*/
}