Differential D17547 Diff 49635 head/lib/libc/sys/open.2

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head/lib/libc/sys/open.2

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	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT			.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY			.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF			.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	.\" SUCH DAMAGE.			.\" SUCH DAMAGE.
	.\"			.\"
	.\" @(#)open.2 8.2 (Berkeley) 11/16/93			.\" @(#)open.2 8.2 (Berkeley) 11/16/93
	.\" $FreeBSD$			.\" $FreeBSD$
	.\"			.\"
	.Dd December 1, 2017			.Dd October 20, 2018
	.Dt OPEN 2			.Dt OPEN 2
	.Os			.Os
	.Sh NAME			.Sh NAME
	.Nm open , openat			.Nm open , openat
	.Nd open or create a file for reading, writing or executing			.Nd open or create a file for reading, writing or executing
	.Sh LIBRARY			.Sh LIBRARY
	.Lb libc			.Lb libc
	.Sh SYNOPSIS			.Sh SYNOPSIS
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	O_FSYNC synchronous writes			O_FSYNC synchronous writes
	O_SYNC synchronous writes			O_SYNC synchronous writes
	O_NOFOLLOW do not follow symlinks			O_NOFOLLOW do not follow symlinks
	O_NOCTTY ignored			O_NOCTTY ignored
	O_TTY_INIT ignored			O_TTY_INIT ignored
	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			O_CLOEXEC set FD_CLOEXEC upon open
	O_VERIFY verify the contents of the file			O_VERIFY verify the contents of the file
				O_BENEATH require path to be strictly relative to starting directory
	.Ed			.Ed
	.Pp			.Pp
	Opening a file with			Opening a file with
	.Dv O_APPEND			.Dv O_APPEND
	set causes each write on the file			set causes each write on the file
	to be appended to the end.			to be appended to the end.
	If			If
	.Dv O_TRUNC			.Dv O_TRUNC
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	may be used to indicate to the kernel that the contents of the file should			may be used to indicate to the kernel that the contents of the file should
	be verified before allowing the open to proceed.			be verified before allowing the open to proceed.
	The details of what			The details of what
	.Dq verified			.Dq verified
	means is implementation specific.			means is implementation specific.
	The run-time linker (rtld) uses this flag to ensure shared objects have			The run-time linker (rtld) uses this flag to ensure shared objects have
	been verified before operating on them.			been verified before operating on them.
	.Pp			.Pp
				.Dv O_BENEATH
				returns
				.Er ENOTCAPABLE
				if the specified path, after resolving all symlinks and ".." references
				in it, does not reside in the directory hierarchy of children beneath
				the starting directory, or is an absolute path.
				Starting directory is the process current directory if relative
				.Fa path
				is used for
				.Fn open ,
				and the directory referenced by the
				.Fa fd
				argument when specifying relative
				.Fa path
				for
				.Fn openat .
				.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.
	It returns \-1 on failure.			It returns \-1 on failure.
	The file pointer used to mark the current position within the			The file pointer used to mark the current position within the
	file is set to the beginning of the file.			file is set to the beginning of the file.
	.Pp			.Pp
	If a sleeping open of a device node from			If a sleeping open of a device node from
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	.It Bq Er ECAPMODE			.It Bq Er ECAPMODE
	.Dv AT_FDCWD			.Dv AT_FDCWD
	is specified and the process is in capability mode.			is specified and the process is in capability mode.
	.It Bq Er ECAPMODE			.It Bq Er ECAPMODE
	.Fn open			.Fn open
	was called and the process is in capability mode.			was called and the process is in capability mode.
	.It Bq Er ENOTCAPABLE			.It Bq Er ENOTCAPABLE
	.Fa path			.Fa path
	is an absolute path or contained a ".." component leading to a			is an absolute path,
				or contained a ".." component leading to a
	directory outside of the directory hierarchy specified by			directory outside of the directory hierarchy specified by
	.Fa fd .			.Fa fd ,
				and the process is in capability mode or the
				.Dv O_BENEATH
				flag was provided.
	.El			.El
	.Sh SEE ALSO			.Sh SEE ALSO
	.Xr chmod 2 ,			.Xr chmod 2 ,
	.Xr close 2 ,			.Xr close 2 ,
	.Xr dup 2 ,			.Xr dup 2 ,
	.Xr fexecve 2 ,			.Xr fexecve 2 ,
	.Xr fhopen 2 ,			.Xr fhopen 2 ,
	.Xr getdtablesize 2 ,			.Xr getdtablesize 2 ,
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