80 lines
1.5 KiB
C
80 lines
1.5 KiB
C
#include <stdio.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <sys/select.h>
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#include <string.h>
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#include <errno.h>
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#define BIG_PIPE_SIZE 64*1024 /* From sys/pipe.h */
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/*
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* Test for the non-blocking big pipe bug (write(2) returning
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* EAGAIN while select(2) returns the descriptor as ready for write).
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*
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* $FreeBSD$
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*/
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void write_frame(int fd, char *buf, unsigned long buflen)
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{
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fd_set wfd;
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int i;
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while (buflen) {
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FD_ZERO(&wfd);
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FD_SET(fd, &wfd);
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i = select(fd+1, NULL, &wfd, NULL, NULL);
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if (i < 0) {
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perror("select");
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exit(1);
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}
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if (i != 1) {
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fprintf(stderr, "select returned unexpected value %d\n", i);
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exit(1);
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}
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i = write(fd, buf, buflen);
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if (i < 0) {
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if (errno != EAGAIN)
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perror("write");
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exit(1);
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}
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buf += i;
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buflen -= i;
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}
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}
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int main()
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{
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char buf[BIG_PIPE_SIZE]; /* any value over PIPE_SIZE should do */
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int i, flags, fd[2];
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if (pipe(fd) < 0) { perror("pipe"); exit(1); }
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flags = fcntl(fd[1], F_GETFL);
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if (flags == -1 || fcntl(fd[1], F_SETFL, flags|O_NONBLOCK) == -1) {
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perror("fcntl");
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exit(1);
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}
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switch (fork()) {
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case -1:
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perror("fork");
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exit(1);
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case 0:
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close(fd[1]);
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for (;;) {
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i = read(fd[0], buf, 256); /* any small size should do */
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if (i == 0) break;
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if (i < 0) { perror("read"); exit(1); }
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}
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exit(0);
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default:
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break;
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}
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close(fd[0]);
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memset(buf, 0, sizeof buf);
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for (i = 0; i < 1000; i++) write_frame(fd[1], buf, sizeof buf);
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exit(0);
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}
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