minix3/tests/t40d.c

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2020-02-21 00:59:27 +05:30
/* t40d.c
*
* Test FIFOs and pipes
*
* Select works on regular files, (pseudo) terminal devices, streams-based
* files, FIFOs, pipes, and sockets. This test verifies selecting for FIFOs
* (named pipes) and pipes (anonymous pipes). This test will not verify most
* error file descriptors, as the setting of this fdset in the face of an error
* condition is implementation-specific (except for regular files (alway set)
* and sockets (protocol-specific or OOB data received), but those file types
* are not being tested in this specific test).
*
* This test is part of a bigger select test. It expects as argument which sub-
* test it is.
*
* [1] If a socket has a pending error, it shall be considered to have an
* exceptional condition pending. Otherwise, what constitutes an exceptional
* condition is file type-specific. For a file descriptor for use with a
* socket, it is protocol-specific except as noted below. For other file types
* it is implementation-defined. If the operation is meaningless for a
* particular file type, pselect() or select() shall indicate that the
* descriptor is ready for read or write operations, and shall indicate that
* the descriptor has no exceptional condition pending.
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/select.h>
#include <errno.h>
#include <sys/wait.h>
#include <string.h>
#include <time.h>
#include <assert.h>
#define NAMEDPIPE1 "selecttestd-1"
#define NAMEDPIPE2 "selecttestd-2"
#define SENDSTRING "minixrocks"
#define DO_HANDLEDATA 1
#define DO_PAUSE 3
#define DO_TIMEOUT 7
#define MAX_ERROR 5
#include "common.h"
char errbuf[1000];
int fd_ap[2]; /* Anonymous pipe; read from fd_ap[0], write to fd_ap[1] */
int fd_np1; /* Named pipe */
int fd_np2; /* Named pipe */
static void do_child(void) {
struct timeval tv;
/* Open named pipe for writing. This will block until a reader arrives. */
if((fd_np1 = open(NAMEDPIPE1, O_WRONLY)) == -1) {
printf("Error opening %s for writing, signalling parent to quit\n",
NAMEDPIPE1);
perror(NULL);
printf("Please make sure that %s is not in use while running this test\n",
NAMEDPIPE1);
exit(-1);
}
/* Going to sleep for three seconds to allow the parent proc to get ready */
tv.tv_sec = DO_HANDLEDATA;
tv.tv_usec = 0;
select(0, NULL, NULL, NULL, &tv);
/* Try to write. Doesn't matter how many bytes we actually send. */
(void) write(fd_np1, SENDSTRING, strlen(SENDSTRING));
/* Wait for another second to allow the parent to process incoming data */
tv.tv_sec = DO_HANDLEDATA;
tv.tv_usec = 0;
(void) select(0,NULL, NULL, NULL, &tv);
close(fd_np1);
/* Wait for another second to allow the parent to process incoming data */
tv.tv_sec = DO_HANDLEDATA;
tv.tv_usec = 0;
(void) select(0,NULL, NULL, NULL, &tv);
/* Open named pipe for reading. This will block until a writer arrives. */
if((fd_np2 = open(NAMEDPIPE2, O_RDONLY)) == -1) {
printf("Error opening %s for reading, signalling parent to quit\n",
NAMEDPIPE2);
perror(NULL);
printf("Please make sure that %s is not in use while running this test\n",
NAMEDPIPE2);
exit(-1);
}
/* Wait for another second to allow the parent to run some tests. */
tv.tv_sec = DO_HANDLEDATA;
tv.tv_usec = 0;
(void) select(0, NULL, NULL, NULL, &tv);
close(fd_np2);
/* Anonymous pipe */
/* Let the parent do initial read and write tests from and to the pipe. */
tv.tv_sec = DO_PAUSE;
tv.tv_usec = 0;
(void) select(0, NULL, NULL, NULL, &tv);
/* Unblock blocking read select by writing data */
if(write(fd_ap[1], SENDSTRING, strlen(SENDSTRING)) < 0) {
perror("Could not write to anonymous pipe");
exit(-1);
}
exit(0);
}
#if 0
static int count_fds(int nfds, fd_set *fds) {
/* Return number of bits set in fds */
int i, result = 0;
assert(fds != NULL && nfds > 0);
for(i = 0; i < nfds; i++) {
if(FD_ISSET(i, fds)) result++;
}
return result;
}
#endif
static int empty_fds(int nfds, fd_set *fds) {
/* Returns nonzero if the first bits up to nfds in fds are not set */
int i;
assert(fds != NULL && nfds > 0);
for(i = 0; i < nfds; i++) if(FD_ISSET(i, fds)) return 0;
return 1;
}
static int compare_fds(int nfds, fd_set *lh, fd_set *rh) {
/* Returns nonzero if lh equals rh up to nfds bits */
int i;
assert(lh != NULL && rh != NULL && nfds > 0);
for(i = 0; i < nfds; i++) {
if((FD_ISSET(i, lh) && !FD_ISSET(i, rh)) ||
(!FD_ISSET(i, lh) && FD_ISSET(i, rh))) {
return 0;
}
}
return 1;
}
#if 0
static void dump_fds(int nfds, fd_set *fds) {
/* Print a graphical representation of bits in fds */
int i;
if(fds != NULL && nfds > 0) {
for(i = 0; i < nfds; i++) printf("%d ", (FD_ISSET(i, fds) ? 1 : 0));
printf("\n");
}
}
#endif
static void do_parent(int child) {
fd_set fds_read, fds_write, fds_error;
fd_set fds_compare_read, fds_compare_write;
struct timeval tv;
time_t start, end;
int retval;
char buf[20];
/* Open named pipe for reading. This will block until a writer arrives. */
if((fd_np1 = open(NAMEDPIPE1, O_RDONLY)) == -1) {
printf("Error opening %s for reading\n", NAMEDPIPE1);
perror(NULL);
printf("Please make sure that %s is not in use while running this test.\n",
NAMEDPIPE1);
waitpid(child, &retval, 0);
exit(-1);
}
/* Clear bit masks */
FD_ZERO(&fds_read); FD_ZERO(&fds_write);
/* Set read and write bits */
FD_SET(fd_np1, &fds_read);
FD_SET(fd_np1, &fds_write);
tv.tv_sec = DO_TIMEOUT;
tv.tv_usec = 0;
/* Test if we can read or write from/to fd_np1. As fd_np1 is opened read only
* we cannot actually write, so the select should return immediately [1] and
* the offending bit set in the fd set. We read from a pipe that is opened
* with O_NONBLOCKING cleared, so it is guaranteed we can read.
* However, at this moment the writer is sleeping, so the pipe is empty and
* read is supposed to block. Therefore, only 1 file descriptor should be
* ready. A timeout value is still set in case an error occurs in a faulty
* implementation. */
retval = select(fd_np1+1, &fds_read, &fds_write, NULL, &tv);
/* Did we receive an error? */
if(retval <= 0) {
snprintf(errbuf, sizeof(errbuf),
"one fd should be set%s", (retval == 0 ? " (TIMEOUT)" : ""));
em(1, errbuf);
}
if(!empty_fds(fd_np1+1,&fds_read)) em(2, "no read bits should be set");
/* Make sure the write bit is set (and just 1 bit) */
FD_ZERO(&fds_compare_write); FD_SET(fd_np1, &fds_compare_write);
if(!compare_fds(fd_np1+1, &fds_compare_write, &fds_write))
em(3, "write should be set");
/* Clear sets and set up new bit masks */
FD_ZERO(&fds_read); FD_ZERO(&fds_write);
FD_SET(fd_np1, &fds_read);
tv.tv_sec = DO_TIMEOUT; /* To make sure we get to see some error messages
instead of blocking forever when the
implementation is faulty. A timeout causes retval
to be 0. */
tv.tv_usec = 0;
/* The sleeping writer is about to wake up and write data to the pipe. */
retval = select(fd_np1+1, &fds_read, &fds_write, NULL, &tv);
/* Correct amount of ready file descriptors? Just 1 read */
if(retval != 1) {
snprintf(errbuf, sizeof(errbuf),
"one fd should be set%s", (retval == 0 ? " (TIMEOUT)" : ""));
em(4, errbuf);
}
if(!FD_ISSET(fd_np1, &fds_read)) em(5, "read should be set");
/* Note that we left the write set empty. This should be equivalent to
* setting this parameter to NULL. */
if(!empty_fds(fd_np1+1, &fds_write)) em(6, "write should NOT be set");
/* In case something went wrong above, we might end up with a child process
* blocking on a write call we close the file descriptor now. Synchronize on
* a read. */
if(read(fd_np1, buf, sizeof(SENDSTRING)) < 0) perror("Read error");
/* Close file descriptor. We're going to reverse the test */
close(fd_np1);
/* Wait for a second to allow the child to close the pipe as well */
tv.tv_sec = DO_HANDLEDATA;
tv.tv_usec = 0;
retval = select(0,NULL, NULL, NULL, &tv);
/* Open named pipe for writing. This call blocks until a reader arrives. */
if((fd_np2 = open(NAMEDPIPE2, O_WRONLY)) == -1) {
printf("Error opening %s for writing\n",
NAMEDPIPE2);
perror(NULL);
printf("Please make sure that %s is not in use while running this test\n",
NAMEDPIPE2);
exit(-1);
}
/* At this moment the child process has opened the named pipe for reading and
* we have opened it for writing. We're now going to reverse some of the
* tests we've done earlier. */
/* Clear sets and set up bit masks */
FD_ZERO(&fds_read); FD_ZERO(&fds_write); FD_ZERO(&fds_error);
FD_SET(fd_np2, &fds_read);
FD_SET(fd_np2, &fds_write);
tv.tv_sec = DO_TIMEOUT;
tv.tv_usec = 0;
/* Select for reading from an fd opened O_WRONLY. This should return
* immediately as it is not a meaningful operation [1] and is therefore not
* blocking. The select should return two file descriptors are ready (the
* failing read and valid write). */
retval = select(fd_np2+1, &fds_read, &fds_write, &fds_error, &tv);
/* Did we receive an error? */
if(retval <= 0) {
snprintf(errbuf, sizeof(errbuf),
"two fds should be set%s", (retval == 0 ? " (TIMEOUT)" : ""));
em(7, errbuf);
}
/* Make sure read bit is set (and just 1 bit) */
FD_ZERO(&fds_compare_read); FD_SET(fd_np2, &fds_compare_read);
if(!compare_fds(fd_np2+1, &fds_compare_read, &fds_read))
em(8, "read should be set");
/* Write bit should be set (and just 1 bit) */
FD_ZERO(&fds_compare_write); FD_SET(fd_np2, &fds_compare_write);
if(!compare_fds(fd_np2+1, &fds_compare_write, &fds_write))
em(9, "write should be set");
if(!empty_fds(fd_np2+1, &fds_error))
em(10, "Error should NOT be set");
FD_ZERO(&fds_read); FD_ZERO(&fds_write);
FD_SET(fd_np2, &fds_write);
tv.tv_sec = DO_TIMEOUT;
tv.tv_usec = 0;
retval = select(fd_np2+1, &fds_read, &fds_write, NULL, &tv);
/* Correct amount of ready file descriptors? Just 1 write */
if(retval != 1) {
snprintf(errbuf, sizeof(errbuf),
"one fd should be set%s", (retval == 0 ? " (TIMEOUT)" : ""));
em(11, errbuf);
}
if(!empty_fds(fd_np2+1, &fds_read)) em(12, "read should NOT be set");
/* Anonymous pipe */
/* Check if we can write to the pipe */
FD_ZERO(&fds_read); FD_ZERO(&fds_write);
FD_SET(fd_ap[1], &fds_write);
tv.tv_sec = DO_TIMEOUT;
tv.tv_usec = 0;
retval = select(fd_ap[1]+1, NULL, &fds_write, NULL, &tv);
/* Correct amount of ready file descriptors? Just 1 write */
if(retval != 1) {
snprintf(errbuf, sizeof(errbuf),
"one fd should be set%s", (retval == 0 ? " (TIMEOUT)" : ""));
em(13, errbuf);
}
/* Make sure write bit is set (and just 1 bit) */
FD_ZERO(&fds_compare_write); FD_SET(fd_ap[1], &fds_compare_write);
if(!compare_fds(fd_ap[1]+1, &fds_compare_write, &fds_write))
em(14, "write should be set");
/* Intentionally test reading from pipe and letting it time out. */
FD_SET(fd_ap[0], &fds_read);
tv.tv_sec = 1;
tv.tv_usec = 0;
start = time(NULL);
retval = select(fd_ap[0]+1, &fds_read, NULL, NULL, &tv);
end = time(NULL);
/* Did we time out? */
if(retval != 0) em(15, "we should have timed out");
/* Did it take us approximately 1 second? */
if((int) (end - start) != 1) {
snprintf(errbuf, sizeof(errbuf),
"time out is not 1 second (instead, it is %ld)",
(long int) (end - start));
em(16, errbuf);
}
/* Do another read, but this time we expect incoming data from child. */
FD_ZERO(&fds_read);
FD_SET(fd_ap[0], &fds_read);
tv.tv_sec = DO_TIMEOUT;
tv.tv_usec = 0;
retval = select(fd_ap[0]+1, &fds_read, NULL, NULL, &tv);
/* Correct amount of ready file descriptors? Just 1 read. */
if(retval != 1) em(17, "one fd should be set");
/* Is the read bit set? And just 1 bit. */
FD_ZERO(&fds_compare_read); FD_SET(fd_ap[0], &fds_compare_read);
if(!compare_fds(fd_ap[0]+1, &fds_compare_read, &fds_read))
em(18, "read should be set.");
/* By convention fd_ap[0] is meant to be used for reading from the pipe and
* fd_ap[1] is meant for writing, where fd_ap is a an anonymous pipe.
* However, it is unspecified what happens when fd_ap[0] is used for writing
* and fd_ap[1] for reading. (It is unsupported on Minix.) As such, it is not
* necessary to make test cases for wrong pipe file descriptors using select.
*/
waitpid(child, &retval, 0);
unlink(NAMEDPIPE2);
unlink(NAMEDPIPE1);
exit(errct);
}
int main(int argc, char **argv) {
int forkres;
/* 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);
}
/* Create named pipe2. It is unlinked by do_parent. */
if(mkfifo(NAMEDPIPE1, 0600) < 0) {
printf("Could not create named pipe %s", NAMEDPIPE1);
perror(NULL);
exit(-1);
}
if(mkfifo(NAMEDPIPE2, 0600) < 0) {
printf("Could not create named pipe %s", NAMEDPIPE2);
perror(NULL);
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*/
}