Add pipe2() system call.

The pipe2() function is similar to pipe() but allows setting FD_CLOEXEC and
O_NONBLOCK (on both sides) as part of the function.

If p points to two writable ints, pipe2(p, 0) is equivalent to pipe(p).

If the pointer is not valid, behaviour differs: pipe2() writes into the
array from the kernel like socketpair() does, while pipe() writes into the
array from an architecture-specific assembler wrapper.

Reviewed by:	kan, kib

include/unistd.h

@@ -533,6 +533,7 @@ char	*mktemp(char *);
 #endif
 int	 nfssvc(int, void *);
 int	 nlm_syscall(int, int, int, char **);
+int	 pipe2(int *, int);
 int	 profil(char *, size_t, vm_offset_t, int);
 int	 rcmd(char **, int, const char *, const char *, const char *, int *);
 int	 rcmd_af(char **, int, const char *,

lib/libc/sys/Makefile.inc

@@ -352,6 +352,7 @@ MLINKS+=pathconf.2 lpathconf.2
 MLINKS+=pdfork.2 pdgetpid.2\
 	pdfork.2 pdkill.2 \
 	pdfork.2 pdwait4.2
+MLINKS+=pipe.2 pipe2.2
 MLINKS+=read.2 pread.2 \
 	read.2 preadv.2 \
 	read.2 readv.2

lib/libc/sys/Symbol.map

@@ -393,6 +393,7 @@ FBSD_1.3 {
 	ffclock_getcounter;
 	ffclock_getestimate;
 	ffclock_setestimate;
+	pipe2;
 	posix_fadvise;
 	wait6;
 };

lib/libc/sys/pipe.2

@@ -28,7 +28,7 @@
 .\"     @(#)pipe.2	8.1 (Berkeley) 6/4/93
 .\" $FreeBSD$
 .\"
-.Dd January 30, 2006
+.Dd March 31, 2013
 .Dt PIPE 2
 .Os
 .Sh NAME
@@ -40,6 +40,8 @@
 .In unistd.h
 .Ft int
 .Fn pipe "int fildes[2]"
+.Ft int
+.Fn pipe2 "int fildes[2]" "int flags"
 .Sh DESCRIPTION
 The
 .Fn pipe
@@ -50,6 +52,29 @@ which is an object allowing
 bidirectional data flow,
 and allocates a pair of file descriptors.
 .Pp
+The
+.Fn pipe2
+system call allows control over the attributes of the file descriptors
+via the
+.Fa flags
+argument.
+Values for
+.Fa flags
+are constructed by a bitwise-inclusive OR of flags from the following
+list, defined in
+.In fcntl.h :
+.Bl -tag -width ".Dv O_NONBLOCK"
+.It Dv O_CLOEXEC
+Set the close-on-exec flag for the new file descriptors.
+.It Dv O_NONBLOCK
+Set the non-blocking flag for the ends of the pipe.
+.El
+.Pp
+If the
+.Fa flags
+argument is 0, the behavior is identical to a call to
+.Fn pipe .
+.Pp
 By convention, the first descriptor is normally used as the
 .Em read end
 of the pipe,
@@ -88,7 +113,9 @@ pipe in one direction.
 .Sh ERRORS
 The
 .Fn pipe
-system call will fail if:
+and
+.Fn pipe2
+system calls will fail if:
 .Bl -tag -width Er
 .It Bq Er EMFILE
 Too many descriptors are active.
@@ -97,6 +124,16 @@ The system file table is full.
 .It Bq Er ENOMEM
 Not enough kernel memory to establish a pipe.
 .El
+.Pp
+The
+.Fn pipe2
+system call will also fail if:
+.Bl -tag -width Er
+.It Bq Er EINVAL
+The
+.Fa flags
+argument is invalid.
+.El
 .Sh SEE ALSO
 .Xr sh 1 ,
 .Xr fork 2 ,
@@ -111,3 +148,8 @@ function appeared in
 .Pp
 Bidirectional pipes were first used on
 .At V.4 .
+.Pp
+The
+.Fn pipe2
+function appeared in
+.Fx 10.0 .

sys/compat/freebsd32/syscalls.master

@@ -1026,3 +1026,4 @@
 				    struct sockaddr * __restrict name, \
 				    __socklen_t * __restrict anamelen, \
 				    int flags); }
+542	AUE_PIPE	NOPROTO	{ int pipe2(int *fildes, int flags); }

sys/kern/capabilities.conf

@@ -490,6 +490,7 @@ pdkill
 ## Allow pipe(2).
 ##
 pipe
+pipe2
 
 ##
 ## Allow poll(2), which will be scoped by capability rights.

sys/kern/sys_pipe.c

@@ -477,6 +477,24 @@ sys_pipe(struct thread *td, struct pipe_args *uap)
 	return (0);
 }
 
+int
+sys_pipe2(struct thread *td, struct pipe2_args *uap)
+{
+	int error, fildes[2];
+
+	if (uap->flags & ~(O_CLOEXEC | O_NONBLOCK))
+		return (EINVAL);
+	error = kern_pipe2(td, fildes, uap->flags);
+	if (error)
+		return (error);
+	error = copyout(fildes, uap->fildes, 2 * sizeof(int));
+	if (error) {
+		(void)kern_close(td, fildes[0]);
+		(void)kern_close(td, fildes[1]);
+	}
+	return (error);
+}
+
 /*
  * Allocate kva for pipe circular buffer, the space is pageable
  * This routine will 'realloc' the size of a pipe safely, if it fails

sys/kern/syscalls.master

@@ -976,5 +976,6 @@
 				    struct sockaddr * __restrict name, \
 				    __socklen_t * __restrict anamelen, \
 				    int flags); }
+542	AUE_PIPE	STD	{ int pipe2(int *fildes, int flags); }
 ; Please copy any additions and changes to the following compatability tables:
 ; sys/compat/freebsd32/syscalls.master