我正在尝试使用RNCryptor在iOS上加密和解密大文件(600 + MB)。在the github上，我找到了有关如何在流上异步使用该库的示例代码。此代码类似于Rob Napier对a question about this same subject的回答。
但是，尽管我认为我正确实现了代码，但该应用程序最多使用1.5 GB的内存(在iPad 6.1模拟器中)。我以为代码应该防止应用程序在内存中保留多个数据块？那么怎么了？
在我的 Controller 中，我创建一个“CryptController”，并通过加密/解密请求进行消息传递。
// Controller.m
NSString *password = @"pw123";
self.cryptor = [[CryptController alloc] initWithPassword:password];
//start encrypting file
[self.cryptor streamEncryptRequest:self.fileName andExtension:@"pdf" withURL:[self samplesURL]];
//wait for encryption to finish
NSDate *timeout = [NSDate dateWithTimeIntervalSinceNow:1];
do {
[[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode
beforeDate:timeout];
} while (![self.cryptor isFinished]);
在CryptController中，我有:
- (void)streamEncryptionDidFinish {
if (self.cryptor.error) {
NSLog(@"An error occurred. You cannot trust decryptedData at this point");
}
else {
NSLog(@"%@ is complete. Use it as you like", [self.tempURL lastPathComponent]);
}
self.cryptor = nil;
self.isFinished = YES;
}
- (void) streamEncryptRequest:(NSString *)fileName andExtension:(NSString *)ext withURL:(NSURL *)directory {
//Make sure that this number is larger than the header + 1 block.
int blockSize = 32 * 1024;
NSString *encryptedFileName = [NSString stringWithFormat:@"streamEnc_%@", fileName];
self.tempURL = [[NSFileManager defaultManager] URLForDirectory:NSDocumentDirectory inDomain:NSUserDomainMask appropriateForURL:nil create:NO error:nil];
self.tempURL = [self.tempURL URLByAppendingPathComponent:encryptedFileName isDirectory:NO];
self.tempURL = [self.tempURL URLByAppendingPathExtension:@"crypt"];
NSInputStream *decryptedStream = [NSInputStream inputStreamWithURL:[[directory URLByAppendingPathComponent:fileName isDirectory:NO] URLByAppendingPathExtension:ext]];
NSOutputStream *cryptedStream = [NSOutputStream outputStreamWithURL:self.tempURL append:NO];
[cryptedStream open];
[decryptedStream open];
__block NSMutableData *data = [NSMutableData dataWithLength:blockSize];
__block RNEncryptor *encryptor = nil;
dispatch_block_t readStreamBlock = ^{
[data setLength:blockSize];
NSInteger bytesRead = [decryptedStream read:[data mutableBytes] maxLength:blockSize];
if (bytesRead < 0) {
//Throw an error
}
else if (bytesRead == 0) {
[encryptor finish];
}
else {
[data setLength:bytesRead];
[encryptor addData:data];
//NSLog(@"Sent %ld bytes to encryptor", (unsigned long)bytesRead);
}
};
encryptor = [[RNEncryptor alloc] initWithSettings:kRNCryptorAES256Settings
password:self.password
handler:^(RNCryptor *cryptor, NSData *data) {
//NSLog(@"Encryptor received %ld bytes", (unsigned long)data.length);
[cryptedStream write:data.bytes maxLength:data.length];
if (cryptor.isFinished) {
[decryptedStream close];
//call my delegate that i'm finished with decrypting
[self streamEncryptionDidFinish];
}
else {
readStreamBlock();
}
}];
// Read the first block to kick things off
self.isFinished = NO;
readStreamBlock();
}
当我使用分配工具进行概要分析时，我看到持续增长的分配类别是
malloc 32.50 KB，malloc 4.00 KB，NSConcreteData和NSSubrangeData。特别是malloc 32.50 KB越来越大，超过1 GB。负责的调用者是[NSConcreteData initWithBytes:length:copy:freeWhenDone:bytesAreVM:]对于NSConcreteData，负责的调用者是-[NSData(NSData) copyWithZone:]。当我使用泄漏仪器进行分析时，没有发现泄漏。
我是Objective-C的新手，据我了解，新的ARC应该可以处理内存的分配和释放。搜寻与内存相关的任何内容时，我发现的所有信息都假设您不使用ARC(或者在撰写本文时不存在)。我肯定使用的是ARC，因为在尝试手动释放内存时出现编译错误，所以我说。
如果有人可以帮助我，将不胜感激!如果需要更多信息，我们将很乐意提供:)
另外，我是StackOverflow的新手，所以如果我忽略了我应该做的任何事情，请通知我!
最佳答案
我终于尝试了给定的解决方案here，它使用信号量而不是依赖于回调来等待流。这很完美:)根据分配工具，内存使用量徘徊在1.1 MB左右。由于信号量语法，它可能看起来不那么整洁，但是至少它可以满足我的要求。
当然仍然欢迎其他建议:)
- (void)encryptWithSemaphore:(NSURL *)url {
dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
__block int total = 0;
int blockSize = 32 * 1024;
NSString *encryptedFile = [[url lastPathComponent] stringByDeletingPathExtension];
NSURL *docsURL = [[NSFileManager defaultManager] URLForDirectory:NSDocumentDirectory inDomain:NSUserDomainMask appropriateForURL:nil create:NO error:nil];
self.tempURL = [[docsURL URLByAppendingPathComponent:encryptedFile isDirectory:NO] URLByAppendingPathExtension:@"crypt"];
NSInputStream *inputStream = [NSInputStream inputStreamWithURL:url];
__block NSOutputStream *outputStream = [NSOutputStream outputStreamWithURL:self.tempURL append:NO];
__block NSError *encryptionError = nil;
[inputStream open];
[outputStream open];
RNEncryptor *encryptor = [[RNEncryptor alloc] initWithSettings:kRNCryptorAES256Settings
password:self.password
handler:^(RNCryptor *cryptor, NSData *data) {
@autoreleasepool {
[outputStream write:data.bytes maxLength:data.length];
dispatch_semaphore_signal(semaphore);
data = nil;
if (cryptor.isFinished) {
[outputStream close];
encryptionError = cryptor.error;
// call my delegate that I'm finished with decrypting
}
}
}];
while (inputStream.hasBytesAvailable) {
@autoreleasepool {
uint8_t buf[blockSize];
NSUInteger bytesRead = [inputStream read:buf maxLength:blockSize];
if (bytesRead > 0) {
NSData *data = [NSData dataWithBytes:buf length:bytesRead];
total = total + bytesRead;
[encryptor addData:data];
dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
}
}
}
[inputStream close];
[encryptor finish];
}
关于ios - 在iOS上使用RNCryptor加密/解密大文件时出现内存问题，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/15335803/