How to programmatically retrieve UUID of root disk partition in OS X?

Question

I can retrieve an OS X disk partition UUID by this code:

void PrintUUID() 
{
    DADiskRef disk;
    CFDictionaryRef descDict;
    DASessionRef session = DASessionCreate(NULL);
    if (session) {
        disk = DADiskCreateFromBSDName(NULL, session, "/dev/disk0s2");
        if (disk) {
            descDict = DADiskCopyDescription(disk);
            if (descDict) {
                CFTypeRef value = (CFTypeRef)CFDictionaryGetValue(descDict,
                    CFSTR("DAVolumeUUID"));
                CFStringRef strValue = CFStringCreateWithFormat(NULL, NULL,
                    CFSTR("%@"), value);
                print(strVal); <------------- here is the output
                CFRelease(strValue);
                CFRelease(descDict);
            }
            CFRelease(disk);
        }
    }
}

Above code retrieve UUID of disk0, I want to retrieve UUID of root disk (mount point = /), if I use "/" instead "/dev/disk0s2" then DADiskCopyDescription returns NULL. Also I know I can do it in Terminal by this command:

diskutil info /

Briefly how can I retrieve BSD Name of root disk? (to use it in DADiskCreateFromBSDName)

Anybody has an idea? Thanks.

Answer 1

Use DADiskCreateFromVolumePath instead of DADiskCreateFromBSDName:

char *mountPoint = "/";
CFURLRef url = CFURLCreateFromFileSystemRepresentation(NULL, (const UInt8 *)mountPoint, strlen(mountPoint), TRUE);
disk = DADiskCreateFromVolumePath(NULL, session, url);
CFRelease(url);

Swift code:

let mountPoint = "/"
let url = URL(fileURLWithPath: mountPoint)
if let session = DASessionCreate(nil),
    let disk = DADiskCreateFromVolumePath(nil, session, url as CFURL),
    let desc = DADiskCopyDescription(disk) as? [String: CFTypeRef] {
    if let uuid = desc["DAVolumeUUID"], CFGetTypeID(uuid) == CFUUIDGetTypeID() {
        if let uuidString = CFUUIDCreateString(nil, (uuid as! CFUUID)) {
            print(uuidString)
        }
    }
}