UNIX Network Programming Volume 2 43rd Page pipeline: Open unexpectedly blocked?

When creating a FIFO pipeline, open will block?
Or is there a problem with my code?

2. #include <stdio.h>
4. #include <unistd.h>
6. #include <fcntl.h>
8. #include <errno.h>
10. #include <sys/types.h>
12. #Include <sys/stat.h>
16. #define FIFO1 "/tmp/fifo.1"
18. #define FIFO2 "/tmp/fifo.2"
22. #define File_mode (S_IRUSR | S_IWUSR | S_irgrp | S_iroth)
26. int main ()
28. {
30. int RfD, WFD;
32. if ((Mkfifo (FIFO1, File_mode) < 0) && errno! = eexist)
34. {//error
36. Exit (0);
38. }
40. if ((Mkfifo (FIFO2, File_mode) < 0) && errno! = eexist)
42. {//error
44. Exit (0);
46. }
48. fprintf (stderr, "before open\n");
50. RFD = open (FIFO1, o_rdonly, 0);
52. WFD = open (FIFO2, o_wronly, 0);
54. fprintf (stderr, "after open\n");
56. There is a problem here and after Open has not been printed.
58. }

Man 3 Open. The interpretation of General 3 is more detailed than the explanation of 2.

1. O_nonblock
2. When opening a FIFO with O_rdonly or o_wronly set:
4. * If O_nonblock is set, a open () for reading-only shall return without delay. An open () for writing-only shall return an error if no process currently have the file open for reading.
6. * If O_nonblock is clear, an open () for reading-only shall block the calling thread until a thread opens the file for Writing. An open () for writing-only shall block, the calling thread until a thread opens the file for reading.

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UNIX Network Programming Volume 2 43rd Page pipeline: Open unexpectedly blocked?