diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/libc/sys/close.2 | 38 |
1 files changed, 21 insertions, 17 deletions
diff --git a/lib/libc/sys/close.2 b/lib/libc/sys/close.2 index c6811b34015..d136f39cd7b 100644 --- a/lib/libc/sys/close.2 +++ b/lib/libc/sys/close.2 @@ -1,4 +1,4 @@ -.\" $OpenBSD: close.2,v 1.11 2004/01/14 09:30:19 tedu Exp $ +.\" $OpenBSD: close.2,v 1.12 2005/08/10 01:25:51 jaredy Exp $ .\" $NetBSD: close.2,v 1.5 1995/02/27 12:32:14 cgd Exp $ .\" .\" Copyright (c) 1980, 1991, 1993, 1994 @@ -47,15 +47,16 @@ call deletes a descriptor from the per-process object reference table. If this is the last reference to the underlying object, the object will be deactivated. -For example, on the last close of a file +For example, on the last close of a file, the current .Em seek pointer associated with the file is lost; on the last close of a -.Xr socket 2 +.Xr socket 2 , associated naming information and queued data are discarded; -on the last close of a file holding an advisory lock -the lock is released. +and on the last close of a file holding an advisory lock, +the lock is released (see further +.Xr flock 2 ) . However, the semantics of System V and .St -p1003.1-88 dictate that all @@ -63,13 +64,11 @@ dictate that all advisory record locks associated with a file for a given process are removed when .Em any -file descriptor for that file is closed by that process (see -further -.Xr flock 2 ) . +file descriptor for that file is closed by that process. .Pp When a process exits, all associated file descriptors are freed, but since there is -a limit on active descriptors per processes, the +a limit on active descriptors per process, the .Fn close function call is useful when a large quantity of file descriptors are being handled. @@ -78,7 +77,7 @@ When a process forks (see .Xr fork 2 ) , all descriptors for the new child process reference the same objects as they did in the parent before the fork. -If a new process is then to be run using +If a new process image is to then be run using .Xr execve 2 , the process would normally inherit these descriptors. Most of the descriptors can be rearranged with @@ -87,15 +86,20 @@ or deleted with .Fn close before the .Xr execve 2 -is attempted, but if some of these descriptors will still -be needed if the execve fails, it is necessary to arrange for them -to be closed if the execve succeeds. +is attempted, but since some of these descriptors may still +be needed should the +.Xr execve 2 +fail, it is necessary to arrange for them +to be closed when the +.Xr execve 2 +succeeds. For this reason, the call -.Dq Li fcntl(d, F_SETFD, 1) +.Fn fcntl d F_SETFD FD_CLOEXEC is provided, which arranges that a descriptor will be closed after a successful -execve; the call -.Dq Li fcntl(d, F_SETFD, 0) +.Xr execve 2 ; +the call +.Fn fcntl d F_SETFD 0 restores the default, which is to not close the descriptor. .Sh RETURN VALUES @@ -108,7 +112,7 @@ is set to indicate the error. will fail if: .Bl -tag -width Er .It Bq Er EBADF -.Fa D +.Fa d is not an active descriptor. .It Bq Er EINTR An interrupt was received. |