playing with cgo and CFPreferencesCopyAppValue. Currently supports reading Strings, NSData, and Booleans.

cfpref.go

package main // import "gitlab.com/clburlison/cfprefs"

import (
	"fmt"
	"unsafe"
)

/*
#cgo LDFLAGS: -framework CoreFoundation
#include <CoreFoundation/CoreFoundation.h>
*/
import "C"

// Convert a Go string to a CFString
// Make sure to release the CFString when finished
func stringToCFString(s string) C.CFStringRef {
	return C.CFStringCreateWithCString(C.kCFAllocatorDefault, C.CString(s), C.kCFStringEncodingUTF8)
}

// Convert a CFString to a Go string
func cfstringToString(s C.CFStringRef) string {
	return C.GoString(C.CFStringGetCStringPtr(s, C.kCFStringEncodingUTF8))
}

// Convert a CFBoolean to a Go bool
func cfbooleanToBoolean(s C.CFBooleanRef) bool {
	// fmt.Println(reflect.TypeOf(C.CFBooleanGetValue(s)))
	if C.CFBooleanGetValue(s) == 1 {
		return true
	}
	return false
}

// Convert a CFData to a Go byte
func cfdataToData(s C.CFDataRef) []uint8 {
	d := C.GoBytes(unsafe.Pointer(C.CFDataGetBytePtr(s)), C.int(C.CFDataGetLength(s)))
	return d
}

// CFPreferencesCopyAppValue - Return a value from a preference
func CFPreferencesCopyAppValue(key string, domain string) interface{} {
	k := stringToCFString(key)
	defer release(C.CFTypeRef(k))
	d := stringToCFString(domain)
	defer release(C.CFTypeRef(d))
	if ret := C.CFPreferencesCopyAppValue(k, d); ret != 0 && C.CFGetTypeID(ret) == C.CFStringGetTypeID() {
		defer release(ret)
		return cfstringToString(C.CFStringRef(ret))
	}
	if ret := C.CFPreferencesCopyAppValue(k, d); ret != 0 && C.CFGetTypeID(ret) == C.CFBooleanGetTypeID() {
		defer release(ret)
		return cfbooleanToBoolean(C.CFBooleanRef(ret))
	}
	if ret := C.CFPreferencesCopyAppValue(k, d); ret != 0 && C.CFGetTypeID(ret) == C.CFDataGetTypeID() {
		defer release(ret)
		return cfdataToData(C.CFDataRef(ret))
	}
	return ""
}

func release(ref C.CFTypeRef) {
	if ref != 0 {
		C.CFRelease(ref)
	}
}

func main() {
	fmt.Printf("%s\n", CFPreferencesCopyAppValue("aData", "com.clburlison.test"))
	fmt.Printf("%v\n", CFPreferencesCopyAppValue("aString", "com.clburlison.test"))
	fmt.Printf("%v\n", CFPreferencesCopyAppValue("aBool", "com.clburlison.test"))

	fmt.Println(C.CFArrayGetTypeID())      // 19
	fmt.Println(C.CFBooleanGetTypeID())    // 21
	fmt.Println(C.CFBundleGetTypeID())     // 31
	fmt.Println(C.CFDataGetTypeID())       // 20
	fmt.Println(C.CFDateGetTypeID())       // 42
	fmt.Println(C.CFDictionaryGetTypeID()) // 18
	fmt.Println(C.CFNullGetTypeID())       // 16
	fmt.Println(C.CFNumberGetTypeID())     // 22
	fmt.Println(C.CFSetGetTypeID())        // 17
	fmt.Println(C.CFStringGetTypeID())     // 7
}

create_prefs.py

#!/usr/bin/python
# Yes I am being lazy and shelling out to defaults :shrug:
import binascii
import subprocess
from Foundation import CFPreferencesCopyAppValue


#filename = "somefile_here"
#with open(filename, 'rb') as f:
#    content = f.read()
content = "asdlfkjasldfihaisygdfkhjawekuyrg1uyg23bkja89c7gd6aikuwherbuy1f46879y8ohjahvsdftya8gisuhdkfbvwuatef87aiuhsdfbyaus687d9f8hubhagsvdufyguihabhsdgvfy78uhabsgvdhfuyiuohjkbgvc123guybhjkijgo897s6tyvg"
hexdata = binascii.hexlify(content)

cmd = [
    "defaults",
    "write",
    "com.clburlison.test",
    "aData",
    "-data",
    hexdata
]
subprocess.check_output(cmd)

cmd = [
    "defaults",
    "write",
    "com.clburlison.test",
    "aString",
    "-string",
    "Hello World"
]
subprocess.check_output(cmd)

cmd = [
    "defaults",
    "write",
    "com.clburlison.test",
    "aBool",
    "-bool",
    "FALSE"
]
subprocess.check_output(cmd)


aData = CFPreferencesCopyAppValue("cert", "com.clburlison.test")
print(aData)

aString = CFPreferencesCopyAppValue("aString", "com.clburlison.test")
print(aString)

aBool = CFPreferencesCopyAppValue("aBool", "com.clburlison.test")
print(aBool)