具有潜在泄漏的 Objective-C Zlib 方法

Question

我刚刚分析了我的代码，发现分析错误。

Potential leak of memory pointed to by 'decompressedBytes'

我从来没有遇到过这样的错误，我已经四处寻找，但不知道如何解决这个“潜在的泄漏”。

这就是我的代码的样子

- (NSData*) dataByDecompressingData:(NSData*)data{
    Byte* bytes = (Byte*)[data bytes];
    NSInteger len = [data length];
    NSMutableData *decompressedData = [[NSMutableData alloc] initWithCapacity:COMPRESSION_BLOCK];
    Byte* decompressedBytes = (Byte*) malloc(COMPRESSION_BLOCK);
    
    z_stream stream;
    int err;
    stream.zalloc = (alloc_func)0;
    stream.zfree = (free_func)0;
    stream.opaque = (voidpf)0;
    
    stream.next_in = bytes;
    err = inflateInit(&stream);
    CHECK_ERR(err, @"inflateInit");
    
    while (true) {
        stream.avail_in = len - stream.total_in;
        stream.next_out = decompressedBytes;
        stream.avail_out = COMPRESSION_BLOCK;
        err = inflate(&stream, Z_NO_FLUSH);
        [decompressedData appendBytes:decompressedBytes length:(stream.total_out-[decompressedData length])];
        if(err == Z_STREAM_END)
            break;
        CHECK_ERR(err, @"inflate");
    }
    
    err = inflateEnd(&stream);
    CHECK_ERR(err, @"inflateEnd");
    
    free(decompressedBytes);
    return decompressedData;
}

Answer 1

如果您的 CHECK_ERR 恰好是 if (err) return nil 之类的东西，则警告意味着您的函数已提前返回，并且可能并不总是释放您 malloced 的内存

如果可能，您应该避免使用malloc。

试试这个

NSMutableData *decompressedBytesData = [[NSMutableData alloc] initWithCapacity:COMPRESSION_BLOCK]; // autorelease if not ARC
Byte* decompressedBytes = (Byte*)[decompressedBytesData mutableBytes];

// you don't need free(decompressedBytes);