(split) LDP: Update original to LDP v3.63

[linuxjm/LDP_man-pages.git] / original / man2 / pipe.2

diff --git a/original/man2/pipe.2 b/original/man2/pipe.2
index a237e6f..a5ed2ea 100644 (file)
--- a/original/man2/pipe.2
+++ b/original/man2/pipe.2
@@ -33,7 +33,7 @@
 .\"     to EXAMPLE text.
 .\" 2008-10-10, mtk: add description of pipe2()
 .\"
-.TH PIPE 2 2012-02-14 "Linux" "Linux Programmer's Manual"
+.TH PIPE 2 2014-02-11 "Linux" "Linux Programmer's Manual"
 .SH NAME
 pipe, pipe2 \- create pipe
 .SH SYNOPSIS
@@ -73,14 +73,6 @@ is the same as
 The following values can be bitwise ORed in
 .IR flags
 to obtain different behavior:
-.TP 12
-.B O_NONBLOCK
-Set the
-.BR O_NONBLOCK
-file status flag on the two new open file descriptions.
-Using this flag saves extra calls to
-.BR fcntl (2)
-to achieve the same result.
 .TP
 .B O_CLOEXEC
 Set the close-on-exec
@@ -89,6 +81,51 @@ flag on the two new file descriptors.
 See the description of the same flag in
 .BR open (2)
 for reasons why this may be useful.
+.TP
+.BR O_DIRECT " (since Linux 3.4)"
+.\" commit 9883035ae7edef3ec62ad215611cb8e17d6a1a5d
+Create a pipe that performs I/O in "packet" mode.
+Each
+.BR write (2)
+to the pipe is dealt with as a separate packet, and
+.BR read (2)s
+from the pipe will read one packet at a time.
+Note the following points:
+.RS
+.IP * 3
+Writes of greater than
+.BR PIPE_BUF
+bytes (see
+.BR pipe (7))
+will be split into multiple packets.
+.IP *
+If a
+.BR read (2)
+specifies a buffer size that is smaller than the next packet,
+then the requested number of bytes are read,
+and the excess bytes in the packet are discarded.
+Specifying a buffer size of
+.BR PIPE_BUF
+will be sufficient to read the largest possible packets
+(see the previous point).
+.IP *
+Zero-length packets are not supported.
+(A
+.BR read (2)
+that specifies a buffer size of zero is a no-op, and returns 0.)
+.RE
+.IP
+Older kernels that do not support this flag will indicate this via an
+.B EINVAL
+error.
+.TP
+.B O_NONBLOCK
+Set the
+.BR O_NONBLOCK
+file status flag on the two new open file descriptions.
+Using this flag saves extra calls to
+.BR fcntl (2)
+to achieve the same result.
 .SH RETURN VALUE
 On success, zero is returned.
 On error, \-1 is returned, and
@@ -137,8 +174,9 @@ The parent then writes the string contained in the program's
 command-line argument to the pipe,
 and the child reads this string a byte at a time from the pipe
 and echoes it on standard output.
+.SS Program source
 .nf
-
+#include <sys/types.h>
 #include <sys/wait.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -153,8 +191,8 @@ main(int argc, char *argv[])
     char buf;
 
     if (argc != 2) {
-       fprintf(stderr, "Usage: %s <string>\\n", argv[0]);
-       exit(EXIT_FAILURE);
+        fprintf(stderr, "Usage: %s <string>\\n", argv[0]);
+        exit(EXIT_FAILURE);
     }
 
     if (pipe(pipefd) == \-1) {