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#include <sys/wait.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <mqueue.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
int main(int argc, char* argv[]) {
struct mq_attr mqattrs = {
.mq_maxmsg = 10,
.mq_msgsize = 128,
};
mqd_t mq = mq_open("/spqueue", O_RDWR | O_CREAT, 0700, &mqattrs);
char buf[128];
pid_t fp = fork();
if (fp == 0) { // child
int amount;
while ((amount = read(0, buf, 128))) {
if (amount < 128) buf[amount] = '\0';
mq_send(mq, buf, 128, 0);
}
}
else {
int fd = open(argv[1], O_WRONLY | O_TRUNC | O_CREAT, 0755);
while (!waitpid(fp, NULL, WNOHANG)) {
mq_receive(mq, buf, 128, NULL);
write(fd, buf, strlen(buf));
}
mq_getattr(mq, &mqattrs);
while (mqattrs.mq_curmsgs-- > 0) {
mq_receive(mq, buf, 128, NULL);
write(fd, buf, strlen(buf));
}
close(fd);
}
mq_close(mq);
if (fp != 0)
mq_unlink("/spqueue");
return 0;
}
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