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| author | Michael Kerrisk <mtk.manpages@gmail.com> | 2016-03-11 07:49:11 +0100 |
|---|---|---|
| committer | Michael Kerrisk <mtk.manpages@gmail.com> | 2016-03-11 07:49:11 +0100 |
| commit | 7255c7c0dfbbacdbca03a53f1cd4563e781627af (patch) | |
| tree | a5e6065e511e169514b9ba9985acab168054c430 | |
| parent | 501934a934566c14b077fe68fc521de2cef76917 (diff) | |
| download | man-pages-7255c7c0dfbbacdbca03a53f1cd4563e781627af.tar.gz | |
fcntl.2: Rework description of F_SETOWN
As suggested by Jason, make it clearer that I/O signalling
requires the use of both F_SETOWN and O_ASYNC. While we're at,
make a few other cleanups to the text.
Reported-by: Jason Vas Dias <jason.vas.dias@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
| -rw-r--r-- | man2/fcntl.2 | 31 |
1 files changed, 17 insertions, 14 deletions
diff --git a/man2/fcntl.2 b/man2/fcntl.2 index d8e09247b8..dc487a8974 100644 --- a/man2/fcntl.2 +++ b/man2/fcntl.2 @@ -681,9 +681,9 @@ Set the process ID or process group ID that will receive .B SIGIO and .B SIGURG -signals for events on file descriptor -.IR fd -to the ID given in +signals for events on the file descriptor +.IR fd . +The target process or process group ID is specified in .IR arg . A process ID is specified as a positive value; a process group ID is specified as a negative value. @@ -693,22 +693,23 @@ Most commonly, the calling process specifies itself as the owner is specified as .BR getpid (2)). -.\" From glibc.info: -If you set the -.B O_ASYNC -status flag on a file descriptor by using the +As well as setting the file descriptor owner, +one must also enable generation of signals on the file descriptor. +This is done by using the +.BR fcntl () .B F_SETFL -command of -.BR fcntl (), -a +command to set the +.B O_ASYNC +file status flag on the file descriptor. +Subsequently, a .B SIGIO signal is sent whenever input or output becomes possible -on that file descriptor. +on the file descriptor. +The +.BR fcntl () .B F_SETSIG -can be used to obtain delivery of a signal other than +command can be used to obtain delivery of a signal other than .BR SIGIO . -If this permission check fails, then the signal is -silently discarded. Sending a signal to the owner process (group) specified by .B F_SETOWN @@ -717,6 +718,8 @@ is subject to the same permissions checks as are described for where the sending process is the one that employs .B F_SETOWN (but see BUGS below). +If this permission check fails, then the signal is +silently discarded. If the file descriptor .I fd |