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Document O_CLOEXEC.

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Reviewed by:	jhb
MFC after:	1 week
This commit is contained in:
Konstantin Belousov 2011-03-25 14:01:18 +00:00
parent 246d35ec91
commit bdadacaf66
1 changed files with 16 additions and 4 deletions
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20
lib/libc/sys/open.2
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@ -28,7 +28,7 @@
.\" @(#)open.2 8.2 (Berkeley) 11/16/93 .\" @(#)open.2 8.2 (Berkeley) 11/16/93
.\" $FreeBSD$ .\" $FreeBSD$
.\" .\"
.Dd February 28, 2009 .Dd March 25, 2011
.Dt OPEN 2 .Dt OPEN 2
.Os .Os
.Sh NAME .Sh NAME
@ -118,6 +118,7 @@ O_NOFOLLOW do not follow symlinks
O_NOCTTY don't assign controlling terminal O_NOCTTY don't assign controlling terminal
O_TTY_INIT restore default terminal attributes O_TTY_INIT restore default terminal attributes
O_DIRECTORY error if file is not a directory O_DIRECTORY error if file is not a directory
O_CLOEXEC set FD_CLOEXEC upon open
.Ed .Ed
.Pp .Pp
Opening a file with Opening a file with
@ -231,6 +232,11 @@ from opening files which are even unsafe to open with
.Dv O_RDONLY , .Dv O_RDONLY ,
such as device nodes. such as device nodes.
.Pp .Pp
.Dv O_CLOEXEC
may be used to set
.Dv FD_CLOEXEC
flag for the newly returned file descriptor.
.Pp
If successful, If successful,
.Fn open .Fn open
returns a non-negative integer, termed a file descriptor. returns a non-negative integer, termed a file descriptor.
@ -241,12 +247,18 @@ file is set to the beginning of the file.
When a new file is created it is given the group of the directory When a new file is created it is given the group of the directory
which contains it. which contains it.
.Pp .Pp
The new descriptor is set to remain open across Unless
.Dv
O_CLOEXEC
flag was specified,
the new descriptor is set to remain open across
.Xr execve 2 .Xr execve 2
system calls; see system calls; see
.Xr close 2 .Xr close 2 ,
.Xr fcntl 2
and and
.Xr fcntl 2 . .Dv O_CLOEXEC
description.
.Pp .Pp
The system imposes a limit on the number of file descriptors The system imposes a limit on the number of file descriptors
open simultaneously by one process. open simultaneously by one process.