diff options
| -rw-r--r-- | lib/libc/sys/fcntl.2 | 55 |
1 files changed, 40 insertions, 15 deletions
diff --git a/lib/libc/sys/fcntl.2 b/lib/libc/sys/fcntl.2 index 23c6606731a..7900869ca68 100644 --- a/lib/libc/sys/fcntl.2 +++ b/lib/libc/sys/fcntl.2 @@ -1,4 +1,4 @@ -.\" $OpenBSD: fcntl.2,v 1.12 1999/05/23 14:10:51 aaron Exp $ +.\" $OpenBSD: fcntl.2,v 1.13 1999/05/25 22:38:01 aaron Exp $ .\" $NetBSD: fcntl.2,v 1.6 1995/02/27 12:32:29 cgd Exp $ .\" .\" Copyright (c) 1983, 1993 @@ -43,15 +43,27 @@ .Sh SYNOPSIS .Fd #include <fcntl.h> .Ft int -.Fn fcntl "int fd" "int cmd" "int arg" +.Fn fcntl "int fd" "int cmd" "..." .Sh DESCRIPTION +The .Fn fcntl -provides for control over descriptors. +provides control over the properties of a file that is already open. The argument .Fa fd is a descriptor to be operated on by .Fa cmd -as follows: +as described below. +The third parameter is called +.Fa arg +and is technically a pointer to +.Fa void , +but is interpreted as an +.Fa int +by some commands, a pointer to a +.Fa struct flock +by others (see below), and ignored by the rest. +.Pp +The commands are: .Bl -tag -width F_GETOWNX .It Dv F_DUPFD Return a new descriptor as follows: @@ -59,7 +71,9 @@ Return a new descriptor as follows: .Bl -bullet -compact -offset 4n .It Lowest numbered available descriptor greater than or equal to -.Fa arg . +.Fa arg +(interpreted as an +.Fa int ) . .It Same object references as the original descriptor. .It @@ -89,16 +103,21 @@ is ignored). .It Dv F_SETFD Set the close-on-exec flag associated with .Fa fd -to the low order bit of +to the low-order bit of .Fa arg -(0 or 1 as above). +(interpreted as an +.Fa int ) . +The flag should be specified as 0 (do not close-on-exec) or +1 (do close-on-exec). .It Dv F_GETFL Get descriptor status flags, as described below .Fa ( arg is ignored). .It Dv F_SETFL Set descriptor status flags to -.Fa arg . +.Fa arg +(interpreted as an +.Fa int ) . .It Dv F_GETOWN Get the process ID or process group currently receiving @@ -118,9 +137,11 @@ and signals; process groups are specified by supplying .Fa arg +(interpreted as an +.Fa int ) as negative, otherwise .Fa arg -is interpreted as a process ID. +is taken as a process ID. .El .Pp The flags for the @@ -130,7 +151,9 @@ and flags are as follows: .Bl -tag -width O_NONBLOCKX .It Dv O_NONBLOCK -Non-blocking I/O; if no data is available to a +Non-blocking +.Tn I/O ; +if no data is available to a .Xr read 2 call, or if a .Xr write 2 @@ -147,7 +170,9 @@ flag of Enable the .Dv SIGIO signal to be sent to the process group -when I/O is possible, e.g., +when +.Tn I/O +is possible, e.g., upon availability of data to be read. .El .Pp @@ -174,7 +199,7 @@ taken as a pointer to a .Fa "struct flock" (see above). The information retrieved overwrites the information passed to -.Nm fcntl +.Fn fcntl in the .Fa flock structure. @@ -197,7 +222,7 @@ or exclusive (or write) locks, as well as remove either type of lock .Dv (F_UNLCK) . If a shared or exclusive lock cannot be set, -.Nm fcntl +.Fn fcntl returns immediately with .Er EAGAIN . .It Dv F_SETLKW @@ -206,9 +231,9 @@ This command is the same as except that if a shared or exclusive lock is blocked by other locks, the process waits until the request can be satisfied. If a signal that is to be caught is received while -.Nm fcntl +.Fn fcntl is waiting for a region, the -.Nm fcntl +.Fn fcntl will be interrupted if the signal handler has not specified the .Dv SA_RESTART (see |