unix: add PidfdOpen and PidfdGetfd

Add wrappers for the pidfd_open and pidfd_getfd sycalls, available since 5.3.

PIDFD_NONBLOCK is defined manually since mkerrors.sh doesn't handle including
linux/pidfd.h well.

See https://man7.org/linux/man-pages/man2/pidfd_open.2.html

Change-Id: I68dfb52f6a7a44b7f3324a8379860a1bb765e71b
Reviewed-on: https://go-review.googlesource.com/c/sys/+/347332
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>

unix/linux/types.go

@@ -3829,3 +3829,9 @@ type LandlockPathBeneathAttr C.struct_landlock_path_beneath_attr
 const (
 	LANDLOCK_RULE_PATH_BENEATH = C.LANDLOCK_RULE_PATH_BENEATH
 )
+
+// pidfd flags.
+
+const (
+	PIDFD_NONBLOCK = C.O_NONBLOCK
+)

unix/syscall_linux.go

@@ -2288,6 +2288,9 @@ type RemoteIovec struct {
 //sys	ProcessVMReadv(pid int, localIov []Iovec, remoteIov []RemoteIovec, flags uint) (n int, err error) = SYS_PROCESS_VM_READV
 //sys	ProcessVMWritev(pid int, localIov []Iovec, remoteIov []RemoteIovec, flags uint) (n int, err error) = SYS_PROCESS_VM_WRITEV
 
+//sys	PidfdOpen(pid int, flags int) (fd int, err error) = SYS_PIDFD_OPEN
+//sys	PidfdGetfd(pidfd int, targetfd int, flags int) (fd int, err error) = SYS_PIDFD_GETFD
+
 /*
  * Unimplemented
  */

unix/zsyscall_linux.go

@@ -1945,6 +1945,28 @@ func ProcessVMWritev(pid int, localIov []Iovec, remoteIov []RemoteIovec, flags u
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func PidfdOpen(pid int, flags int) (fd int, err error) {
+	r0, _, e1 := Syscall(SYS_PIDFD_OPEN, uintptr(pid), uintptr(flags), 0)
+	fd = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func PidfdGetfd(pidfd int, targetfd int, flags int) (fd int, err error) {
+	r0, _, e1 := Syscall(SYS_PIDFD_GETFD, uintptr(pidfd), uintptr(targetfd), uintptr(flags))
+	fd = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func pipe2(p *[2]_C_int, flags int) (err error) {
 	_, _, e1 := RawSyscall(SYS_PIPE2, uintptr(unsafe.Pointer(p)), uintptr(flags), 0)
 	if e1 != 0 {

unix/ztypes_linux_386.go

@@ -635,3 +635,7 @@ const (
 	PPS_GETCAP    = 0x800470a3
 	PPS_FETCH     = 0xc00470a4
 )
+
+const (
+	PIDFD_NONBLOCK = 0x800
+)

unix/ztypes_linux_amd64.go

@@ -653,3 +653,7 @@ const (
 	PPS_GETCAP    = 0x800870a3
 	PPS_FETCH     = 0xc00870a4
 )
+
+const (
+	PIDFD_NONBLOCK = 0x800
+)

unix/ztypes_linux_arm.go

@@ -630,3 +630,7 @@ const (
 	PPS_GETCAP    = 0x800470a3
 	PPS_FETCH     = 0xc00470a4
 )
+
+const (
+	PIDFD_NONBLOCK = 0x800
+)

unix/ztypes_linux_arm64.go

@@ -632,3 +632,7 @@ const (
 	PPS_GETCAP    = 0x800870a3
 	PPS_FETCH     = 0xc00870a4
 )
+
+const (
+	PIDFD_NONBLOCK = 0x800
+)

unix/ztypes_linux_mips.go

@@ -636,3 +636,7 @@ const (
 	PPS_GETCAP    = 0x400470a3
 	PPS_FETCH     = 0xc00470a4
 )
+
+const (
+	PIDFD_NONBLOCK = 0x80
+)

unix/ztypes_linux_mips64.go

@@ -635,3 +635,7 @@ const (
 	PPS_GETCAP    = 0x400870a3
 	PPS_FETCH     = 0xc00870a4
 )
+
+const (
+	PIDFD_NONBLOCK = 0x80
+)

unix/ztypes_linux_mips64le.go

@@ -635,3 +635,7 @@ const (
 	PPS_GETCAP    = 0x400870a3
 	PPS_FETCH     = 0xc00870a4
 )
+
+const (
+	PIDFD_NONBLOCK = 0x80
+)

unix/ztypes_linux_mipsle.go

@@ -636,3 +636,7 @@ const (
 	PPS_GETCAP    = 0x400470a3
 	PPS_FETCH     = 0xc00470a4
 )
+
+const (
+	PIDFD_NONBLOCK = 0x80
+)

unix/ztypes_linux_ppc.go

@@ -642,3 +642,7 @@ const (
 	PPS_GETCAP    = 0x400470a3
 	PPS_FETCH     = 0xc00470a4
 )
+
+const (
+	PIDFD_NONBLOCK = 0x800
+)

unix/ztypes_linux_ppc64.go

@@ -642,3 +642,7 @@ const (
 	PPS_GETCAP    = 0x400870a3
 	PPS_FETCH     = 0xc00870a4
 )
+
+const (
+	PIDFD_NONBLOCK = 0x800
+)

unix/ztypes_linux_ppc64le.go

@@ -642,3 +642,7 @@ const (
 	PPS_GETCAP    = 0x400870a3
 	PPS_FETCH     = 0xc00870a4
 )
+
+const (
+	PIDFD_NONBLOCK = 0x800
+)

unix/ztypes_linux_riscv64.go

@@ -660,3 +660,7 @@ const (
 	PPS_GETCAP    = 0x800870a3
 	PPS_FETCH     = 0xc00870a4
 )
+
+const (
+	PIDFD_NONBLOCK = 0x800
+)

unix/ztypes_linux_s390x.go

@@ -656,3 +656,7 @@ const (
 	PPS_GETCAP    = 0x800870a3
 	PPS_FETCH     = 0xc00870a4
 )
+
+const (
+	PIDFD_NONBLOCK = 0x800
+)

unix/ztypes_linux_sparc64.go

@@ -637,3 +637,7 @@ const (
 	PPS_GETCAP    = 0x400870a3
 	PPS_FETCH     = 0xc00870a4
 )
+
+const (
+	PIDFD_NONBLOCK = 0x4000
+)