MacMonitor/Sources/Hardware/AppleSMC/MMAppleSMCClient.m

#import "MMAppleSMCClient.h"
#import <IOKit/IOKitLib.h>
#import <os/lock.h>

@interface MMAppleSMCClient () {
    os_unfair_lock _lock;
    io_connect_t _connection;
    NSMutableDictionary<NSString *, NSValue *> *_keyInfoCache;
    BOOL _opened;
    NSInteger _totalKeyCount;
}
@end

@implementation MMAppleSMCClient

+ (instancetype)sharedClient {
    static MMAppleSMCClient *instance = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        instance = [[self alloc] init];
    });
    return instance;
}

- (instancetype)init {
    self = [super init];
    if (self) {
        _lock = OS_UNFAIR_LOCK_INIT;
        _keyInfoCache = [NSMutableDictionary dictionary];
        [self openWithError:nil];
    }
    return self;
}

- (void)dealloc {
    [self close];
}

- (BOOL)isAvailable {
    os_unfair_lock_lock(&_lock);
    BOOL avail = (_connection != IO_OBJECT_NULL && _opened);
    os_unfair_lock_unlock(&_lock);
    return avail;
}

- (NSInteger)totalKeyCount {
    os_unfair_lock_lock(&_lock);
    NSInteger count = _totalKeyCount;
    os_unfair_lock_unlock(&_lock);
    return count;
}

- (BOOL)openWithError:(NSError **)error {
    os_unfair_lock_lock(&_lock);
    if (_opened && _connection != IO_OBJECT_NULL) {
        os_unfair_lock_unlock(&_lock);
        return YES;
    }
    
    CFMutableDictionaryRef matching = IOServiceMatching("AppleSMCClient");
    if (!matching) {
        os_unfair_lock_unlock(&_lock);
        if (error) {
            *error = [NSError errorWithDomain:@"com.i3omb.MacMonitor.SMC"
                                         code:-1
                                     userInfo:@{NSLocalizedDescriptionKey: @"Failed to create AppleSMCClient matching dictionary"}];
        }
        return NO;
    }
    
    io_service_t service = IOServiceGetMatchingService(kIOMainPortDefault, matching);
    if (service == IO_OBJECT_NULL) {
        os_unfair_lock_unlock(&_lock);
        if (error) {
            *error = [NSError errorWithDomain:@"com.i3omb.MacMonitor.SMC"
                                         code:-2
                                     userInfo:@{NSLocalizedDescriptionKey: @"AppleSMCClient service not found (running on non-Mac or unsupported VM)"}];
        }
        return NO;
    }
    
    kern_return_t kr = IOServiceOpen(service, mach_task_self(), 0, &_connection);
    IOObjectRelease(service);
    
    if (kr != KERN_SUCCESS || _connection == IO_OBJECT_NULL) {
        _connection = IO_OBJECT_NULL;
        _opened = NO;
        os_unfair_lock_unlock(&_lock);
        if (error) {
            *error = [NSError errorWithDomain:@"com.i3omb.MacMonitor.SMC"
                                         code:kr
                                     userInfo:@{NSLocalizedDescriptionKey: [NSString stringWithFormat:@"IOServiceOpen failed with code: 0x%x", kr]}];
        }
        return NO;
    }
    
    _opened = YES;
    os_unfair_lock_unlock(&_lock);
    
    // Probe total keys count
    NSNumber *keysCount = [self readNumericValueForKey:@"#KEY" error:nil];
    if (keysCount) {
        os_unfair_lock_lock(&_lock);
        _totalKeyCount = [keysCount integerValue];
        os_unfair_lock_unlock(&_lock);
    }
    
    return YES;
}

- (void)close {
    os_unfair_lock_lock(&_lock);
    if (_connection != IO_OBJECT_NULL) {
        IOServiceClose(_connection);
        _connection = IO_OBJECT_NULL;
    }
    _opened = NO;
    [_keyInfoCache removeAllObjects];
    os_unfair_lock_unlock(&_lock);
}

- (BOOL)callSMCWithInput:(const SMCKeyData_t *)input output:(SMCKeyData_t *)output {
    if (_connection == IO_OBJECT_NULL) return NO;
    
    size_t inputSize = sizeof(SMCKeyData_t);
    size_t outputSize = sizeof(SMCKeyData_t);
    
    kern_return_t kr = IOConnectCallStructMethod(
        _connection,
        kSMCHandleYPCEvent,
        input,
        inputSize,
        output,
        &outputSize
    );
    
    return (kr == KERN_SUCCESS && output->result == 0);
}

- (BOOL)fetchKeyInfo:(NSString *)key info:(SMCKeyInfoData *)outInfo {
    if (key.length != 4) return NO;
    
    os_unfair_lock_lock(&_lock);
    NSValue *cached = _keyInfoCache[key];
    if (cached) {
        [cached getValue:outInfo size:sizeof(SMCKeyInfoData)];
        os_unfair_lock_unlock(&_lock);
        return YES;
    }
    
    SMCKeyData_t input = {0};
    SMCKeyData_t output = {0};
    
    input.key = MMSMCToFourCharCode([key UTF8String]);
    input.data8 = kSMCGetKeyInfo;
    
    BOOL success = [self callSMCWithInput:&input output:&output];
    if (success) {
        *outInfo = output.keyInfo;
        _keyInfoCache[key] = [NSValue value:outInfo withObjCType:@encode(SMCKeyInfoData)];
    }
    
    os_unfair_lock_unlock(&_lock);
    return success;
}

- (nullable NSData *)readBytesForKey:(NSString *)key error:(NSError **)error {
    if (![self isAvailable]) {
        if (![self openWithError:error]) return nil;
    }
    
    SMCKeyInfoData info = {0};
    if (![self fetchKeyInfo:key info:&info]) {
        if (error) {
            *error = [NSError errorWithDomain:@"com.i3omb.MacMonitor.SMC"
                                         code:-3
                                     userInfo:@{NSLocalizedDescriptionKey: [NSString stringWithFormat:@"Failed to retrieve key info for '%@'", key]}];
        }
        return nil;
    }
    
    if (info.dataSize > 32) {
        if (error) {
            *error = [NSError errorWithDomain:@"com.i3omb.MacMonitor.SMC"
                                         code:-4
                                     userInfo:@{NSLocalizedDescriptionKey: [NSString stringWithFormat:@"Data size %lu exceeds 32 bytes for key '%@'", (unsigned long)info.dataSize, key]}];
        }
        return nil;
    }
    
    os_unfair_lock_lock(&_lock);
    SMCKeyData_t input = {0};
    SMCKeyData_t output = {0};
    
    input.key = MMSMCToFourCharCode([key UTF8String]);
    input.keyInfo.dataSize = info.dataSize;
    input.data8 = kSMCReadKey;
    
    BOOL success = [self callSMCWithInput:&input output:&output];
    os_unfair_lock_unlock(&_lock);
    
    if (!success) {
        if (error) {
            *error = [NSError errorWithDomain:@"com.i3omb.MacMonitor.SMC"
                                         code:-5
                                     userInfo:@{NSLocalizedDescriptionKey: [NSString stringWithFormat:@"SMC read command failed for key '%@'", key]}];
        }
        return nil;
    }
    
    return [NSData dataWithBytes:output.bytes length:info.dataSize];
}

- (nullable NSString *)readDataTypeForKey:(NSString *)key error:(NSError **)error {
    SMCKeyInfoData info = {0};
    if (![self fetchKeyInfo:key info:&info]) {
        if (error) {
            *error = [NSError errorWithDomain:@"com.i3omb.MacMonitor.SMC"
                                         code:-3
                                     userInfo:@{NSLocalizedDescriptionKey: [NSString stringWithFormat:@"Failed to retrieve key info for '%@'", key]}];
        }
        return nil;
    }
    char typeStr[5] = {0};
    MMSMCFromFourCharCode(info.dataType, typeStr);
    return [NSString stringWithUTF8String:typeStr];
}

- (nullable NSNumber *)readNumericValueForKey:(NSString *)key error:(NSError **)error {
    SMCKeyInfoData info = {0};
    if (![self fetchKeyInfo:key info:&info]) {
        return nil;
    }
    
    NSData *data = [self readBytesForKey:key error:error];
    if (!data) return nil;
    
    char typeStr[5] = {0};
    MMSMCFromFourCharCode(info.dataType, typeStr);
    NSString *dataType = [NSString stringWithUTF8String:typeStr];
    
    return [MMSMCParser decodeValueWithDataType:dataType bytes:data.bytes size:data.length];
}

@end