unix: add bindings for kinfo_proc on Darwin

On Linux, we can extract a list of all the processes on the system by
calling readdir() against /proc. On BSD-like systems, this information
needs to be extracted from sysctl in the form of kinfo_proc structures.

This change adds bindings for this structure and adds a method for
reading an array of these structures from sysctl.

unix/mkpost.go

@@ -50,6 +50,21 @@ func main() {
 		b = sttimespec.ReplaceAll(b, []byte("Timespec"))
 	}
 
+	if goos == "darwin" {
+		// KinfoProc contains various pointers to objects stored
+		// in kernel space. Replace these by uintptr to prevent
+		// accidental dereferencing.
+		kinfoProcPointerRegex := regexp.MustCompile(`\*_Ctype_struct_(pgrp|proc|session|sigacts|ucred|user|vnode)`)
+		b = kinfoProcPointerRegex.ReplaceAll(b, []byte("uintptr"))
+
+		// ExternProc contains a p_un member that in kernel
+		// space stores a pair of pointers and in user space
+		// stores the process creation time. We only care about
+		// the process creation time.
+		externProcStarttimeRegex := regexp.MustCompile(`P_un\s*\[\d+\]byte`)
+		b = externProcStarttimeRegex.ReplaceAll(b, []byte("P_starttime Timeval"))
+	}
+
 	// Intentionally export __val fields in Fsid and Sigset_t
 	valRegex := regexp.MustCompile(`type (Fsid|Sigset_t) struct {(\s+)X__(bits|val)(\s+\S+\s+)}`)
 	b = valRegex.ReplaceAll(b, []byte("type $1 struct {${2}Val$4}"))

unix/syscall_darwin.go

@@ -13,6 +13,7 @@
 package unix
 
 import (
+	"fmt"
 	"runtime"
 	"syscall"
 	"unsafe"
@@ -398,6 +399,38 @@ func GetsockoptXucred(fd, level, opt int) (*Xucred, error) {
 	return x, err
 }
 
+func SysctlKinfoProcSlice(name string) ([]KinfoProc, error) {
+	mib, err := sysctlmib(name)
+	if err != nil {
+		return nil, err
+	}
+
+	// Find size.
+	n := uintptr(0)
+	if err := sysctl(mib, nil, &n, nil, 0); err != nil {
+		return nil, err
+	}
+	if n == 0 {
+		return nil, nil
+	}
+	if n%SizeofKinfoProc != 0 {
+		return nil, fmt.Errorf("sysctl() returned a size of %d, which is not a multiple of %d", n, SizeofKinfoProc)
+	}
+
+	// Read into buffer of that size.
+	buf := make([]KinfoProc, n/SizeofKinfoProc)
+	if err := sysctl(mib, (*byte)(unsafe.Pointer(&buf[0])), &n, nil, 0); err != nil {
+		return nil, err
+	}
+	if n%SizeofKinfoProc != 0 {
+		return nil, fmt.Errorf("sysctl() returned a size of %d, which is not a multiple of %d", n, SizeofKinfoProc)
+	}
+
+	// The actual call may return less than the original reported required
+	// size so ensure we deal with that.
+	return buf[:n/SizeofKinfoProc], nil
+}
+
 //sys	sendfile(infd int, outfd int, offset int64, len *int64, hdtr unsafe.Pointer, flags int) (err error)
 
 /*

unix/types_darwin.go

@@ -37,6 +37,7 @@ package unix
 #include <sys/signal.h>
 #include <sys/socket.h>
 #include <sys/stat.h>
+#include <sys/sysctl.h>
 #include <sys/time.h>
 #include <sys/types.h>
 #include <sys/ucred.h>
@@ -304,3 +305,21 @@ type Clockinfo C.struct_clockinfo
 // ctl_info
 
 type CtlInfo C.struct_ctl_info
+
+// KinfoProc
+
+const SizeofKinfoProc = C.sizeof_struct_kinfo_proc
+
+type Eproc C.struct_eproc
+
+type ExternProc C.struct_extern_proc
+
+type Itimerval C.struct_itimerval
+
+type KinfoProc C.struct_kinfo_proc
+
+type Vmspace C.struct_vmspace
+
+type Pcred C.struct__pcred
+
+type Ucred C.struct__ucred

unix/ztypes_darwin_amd64.go

@@ -535,3 +535,107 @@ type CtlInfo struct {
 	Id   uint32
 	Name [96]byte
 }
+
+const SizeofKinfoProc = 0x288
+
+type Eproc struct {
+	Paddr   uintptr
+	Sess    uintptr
+	Pcred   Pcred
+	Ucred   Ucred
+	Vm      Vmspace
+	Ppid    int32
+	Pgid    int32
+	Jobc    int16
+	Tdev    int32
+	Tpgid   int32
+	Tsess   uintptr
+	Wmesg   [8]int8
+	Xsize   int32
+	Xrssize int16
+	Xccount int16
+	Xswrss  int16
+	Flag    int32
+	Login   [12]int8
+	Spare   [4]int32
+	_       [4]byte
+}
+
+type ExternProc struct {
+	P_starttime Timeval
+	P_vmspace   *Vmspace
+	P_sigacts   uintptr
+	P_flag      int32
+	P_stat      int8
+	P_pid       int32
+	P_oppid     int32
+	P_dupfd     int32
+	User_stack  *int8
+	Exit_thread *byte
+	P_debugger  int32
+	Sigwait     int32
+	P_estcpu    uint32
+	P_cpticks   int32
+	P_pctcpu    uint32
+	P_wchan     *byte
+	P_wmesg     *int8
+	P_swtime    uint32
+	P_slptime   uint32
+	P_realtimer Itimerval
+	P_rtime     Timeval
+	P_uticks    uint64
+	P_sticks    uint64
+	P_iticks    uint64
+	P_traceflag int32
+	P_tracep    uintptr
+	P_siglist   int32
+	P_textvp    uintptr
+	P_holdcnt   int32
+	P_sigmask   uint32
+	P_sigignore uint32
+	P_sigcatch  uint32
+	P_priority  uint8
+	P_usrpri    uint8
+	P_nice      int8
+	P_comm      [17]int8
+	P_pgrp      uintptr
+	P_addr      uintptr
+	P_xstat     uint16
+	P_acflag    uint16
+	P_ru        *Rusage
+}
+
+type Itimerval struct {
+	Interval Timeval
+	Value    Timeval
+}
+
+type KinfoProc struct {
+	Proc  ExternProc
+	Eproc Eproc
+}
+
+type Vmspace struct {
+	Dummy  int32
+	Dummy2 *int8
+	Dummy3 [5]int32
+	Dummy4 [3]*int8
+}
+
+type Pcred struct {
+	Pc_lock  [72]int8
+	Pc_ucred uintptr
+	P_ruid   uint32
+	P_svuid  uint32
+	P_rgid   uint32
+	P_svgid  uint32
+	P_refcnt int32
+	_        [4]byte
+}
+
+type Ucred struct {
+	Ref     int32
+	Uid     uint32
+	Ngroups int16
+	Groups  [16]uint32
+}

unix/ztypes_darwin_arm64.go

@@ -535,3 +535,107 @@ type CtlInfo struct {
 	Id   uint32
 	Name [96]byte
 }
+
+const SizeofKinfoProc = 0x288
+
+type Eproc struct {
+	Paddr   uintptr
+	Sess    uintptr
+	Pcred   Pcred
+	Ucred   Ucred
+	Vm      Vmspace
+	Ppid    int32
+	Pgid    int32
+	Jobc    int16
+	Tdev    int32
+	Tpgid   int32
+	Tsess   uintptr
+	Wmesg   [8]int8
+	Xsize   int32
+	Xrssize int16
+	Xccount int16
+	Xswrss  int16
+	Flag    int32
+	Login   [12]int8
+	Spare   [4]int32
+	_       [4]byte
+}
+
+type ExternProc struct {
+	P_starttime Timeval
+	P_vmspace   *Vmspace
+	P_sigacts   uintptr
+	P_flag      int32
+	P_stat      int8
+	P_pid       int32
+	P_oppid     int32
+	P_dupfd     int32
+	User_stack  *int8
+	Exit_thread *byte
+	P_debugger  int32
+	Sigwait     int32
+	P_estcpu    uint32
+	P_cpticks   int32
+	P_pctcpu    uint32
+	P_wchan     *byte
+	P_wmesg     *int8
+	P_swtime    uint32
+	P_slptime   uint32
+	P_realtimer Itimerval
+	P_rtime     Timeval
+	P_uticks    uint64
+	P_sticks    uint64
+	P_iticks    uint64
+	P_traceflag int32
+	P_tracep    uintptr
+	P_siglist   int32
+	P_textvp    uintptr
+	P_holdcnt   int32
+	P_sigmask   uint32
+	P_sigignore uint32
+	P_sigcatch  uint32
+	P_priority  uint8
+	P_usrpri    uint8
+	P_nice      int8
+	P_comm      [17]int8
+	P_pgrp      uintptr
+	P_addr      uintptr
+	P_xstat     uint16
+	P_acflag    uint16
+	P_ru        *Rusage
+}
+
+type Itimerval struct {
+	Interval Timeval
+	Value    Timeval
+}
+
+type KinfoProc struct {
+	Proc  ExternProc
+	Eproc Eproc
+}
+
+type Vmspace struct {
+	Dummy  int32
+	Dummy2 *int8
+	Dummy3 [5]int32
+	Dummy4 [3]*int8
+}
+
+type Pcred struct {
+	Pc_lock  [72]int8
+	Pc_ucred uintptr
+	P_ruid   uint32
+	P_svuid  uint32
+	P_rgid   uint32
+	P_svgid  uint32
+	P_refcnt int32
+	_        [4]byte
+}
+
+type Ucred struct {
+	Ref     int32
+	Uid     uint32
+	Ngroups int16
+	Groups  [16]uint32
+}