From github.com/gsscoder/goproc as in commit 13a38b6100

process_darwin.go

// Copyright 2015 Giacomo Stelluti Scala. All rights reserved. See doc/License.md in the project root for license information.

package process

/*
#include <stdlib.h>
#include "libproc.h"
*/
import "C"
import "unsafe"
import "strings"
import "strconv"

//import "fmt"

type go_proc_taskinfo struct { // same as sys/proc_info.h/proc_taskinfo
	pti_virtual_size      C.uint64_t // virtual memory size (bytes)
	pti_resident_size     C.uint64_t // resident memory size (bytes)
	pti_total_user        C.uint64_t // total time
	pti_total_system      C.uint64_t
	pti_threads_user      C.uint64_t // existing threads only
	pti_threads_system    C.uint64_t
	pti_policy            C.int32_t // default policy for new threads
	pti_faults            C.int32_t // number of page faults
	pti_pageins           C.int32_t // number of actual pageins
	pti_cow_faults        C.int32_t // number of copy-on-write faults
	pti_messages_sent     C.int32_t // number of messages sent
	pti_messages_received C.int32_t // number of messages received
	pti_syscalls_mach     C.int32_t // number of mach system calls
	pti_syscalls_unix     C.int32_t // number of unix system calls
	pti_csw               C.int32_t // number of context switches
	pti_threadnum         C.int32_t // number of threads in the task
	pti_numrunning        C.int32_t // number of running threads
	pti_priority          C.int32_t // task priority
}

func nameOf(pid int) string {
	name := C.CString(strings.Repeat("\x00", 1024))
	namePtr := unsafe.Pointer(name)
	defer C.free(namePtr)
	nameLen := C.proc_name(C.int(pid), namePtr, C.uint32_t(1024))
	var result string

	if nameLen > 0 {
		result = C.GoString(name)
	} else {
		result = ""
	}

	return result
}

func count() int {
	procs := int(C.proc_listallpids(nil, C.int(0)))
	if procs <= 0 {
		return 0
	} else {
		return procs
	}
}

func listPids() []int {
	cnt := count()
	if cnt <= 0 {
		return make([]int, 0)
	}
	pids := C.malloc(C.size_t(cnt * int(unsafe.Sizeof(C.int(0)))))
	if pids == nil {
		return make([]int, 0)
	}
	defer C.free(unsafe.Pointer(pids))
	pidsCnt := C.proc_listallpids(pids, C.int(cnt*int(unsafe.Sizeof(C.int(0)))))
	if pidsCnt <= 0 {
		return make([]int, 0)
	}
	casted := (*[1 << 20]C.int)(unsafe.Pointer(pids))
	pidsCopy := make([]int, cnt)
	for i := 0; i < cnt; i++ {
		pidsCopy[i] = int(casted[i])
	}
	return trimPidArray(pidsCopy)
}

func propertiesOf(pid int, keys []int) PropertyMap {
	result := make(PropertyMap)

	info := C.malloc(C.size_t(C.PROC_PIDTASKINFO_SIZE))
	defer C.free(info)
	actualSize := C.proc_pidinfo(C.int(pid), C.PROC_PIDTASKINFO, 0, info, C.int(C.PROC_PIDTASKINFO_SIZE)) //C.int(unsafe.Sizeof(info)))
	// checking size as described in http://goo.gl/Lta0IO
	if actualSize < C.int(unsafe.Sizeof(info)) {
		//panic(fmt.Sprintf("actualsize=%d\n, sizeof(info)=%d", int(actualSize), int(C.int(unsafe.Sizeof(info))))) //DEBUG
		return result
	}
	casted := (*go_proc_taskinfo)(info)

	for _, key := range keys {
		switch key {
		case PropertyVMSize:
			result[PropertyVMSize] = strconv.FormatInt(int64(casted.pti_virtual_size), 10)
		}
	}

	return result
}

func trimPidArray(pids []int) []int {
	index := len(pids)
	for i, e := range pids {
		if e <= 0 {
			index = i
			break
		}
	}
	return pids[0:index]
}