1 #include <sys/select.h>
2 #include <err.h>
3 #include <errno.h>
4 #include <fcntl.h>
5 #include <stdio.h>
6 #include <stdlib.h>
7 #include <string.h>
8 #include <unistd.h>
9
10 #define BIG_PIPE_SIZE 64*1024 /* From sys/pipe.h */
11
12 /*
13 * Test for the non-blocking big pipe bug (write(2) returning
14 * EAGAIN while select(2) returns the descriptor as ready for write).
15 *
16 * $FreeBSD$
17 */
18
19 static void
write_frame(int fd,char * buf,unsigned long buflen)20 write_frame(int fd, char *buf, unsigned long buflen)
21 {
22 fd_set wfd;
23 int i;
24
25 while (buflen) {
26 FD_ZERO(&wfd);
27 FD_SET(fd, &wfd);
28 i = select(fd+1, NULL, &wfd, NULL, NULL);
29 if (i < 0)
30 err(1, "select failed");
31 if (i != 1) {
32 errx(1, "select returned unexpected value %d\n", i);
33 exit(1);
34 }
35 i = write(fd, buf, buflen);
36 if (i < 0) {
37 if (errno != EAGAIN)
38 warn("write failed");
39 exit(1);
40 }
41 buf += i;
42 buflen -= i;
43 }
44 }
45
46 int
main(void)47 main(void)
48 {
49 /* any value over PIPE_SIZE should do */
50 char buf[BIG_PIPE_SIZE];
51 int i, flags, fd[2];
52
53 if (pipe(fd) < 0)
54 errx(1, "pipe failed");
55
56 flags = fcntl(fd[1], F_GETFL);
57 if (flags == -1 || fcntl(fd[1], F_SETFL, flags|O_NONBLOCK) == -1) {
58 printf("fcntl failed: %s\n", strerror(errno));
59 exit(1);
60 }
61
62 switch (fork()) {
63 case -1:
64 err(1, "fork failed: %s\n", strerror(errno));
65 break;
66 case 0:
67 close(fd[1]);
68 for (;;) {
69 /* Any small size should do */
70 i = read(fd[0], buf, 256);
71 if (i == 0)
72 break;
73 if (i < 0)
74 err(1, "read");
75 }
76 exit(0);
77 default:
78 break;
79 }
80
81 close(fd[0]);
82 memset(buf, 0, sizeof buf);
83 for (i = 0; i < 1000; i++)
84 write_frame(fd[1], buf, sizeof buf);
85
86 printf("ok\n");
87 exit(0);
88 }
89