iOS解压Windows生成的gzip文件时触发UNZ_BADZIPFILE(-103)错误求助

问题 #

我们用C# Windows控制台应用，通过System.IO.Compression.GZipStream压缩SQLite文件，生成的.gzip文件上传到服务器后供iOS端下载。现在遇到的问题是：iOS应用用SSZipArchive库解压时触发UNZ_BADZIPFILE(-103)错误，但在Mac上手动下载该文件后，用SSZipArchive能正常解压。想问是否需要做编码处理，让iOS识别Windows生成的gzip文件？

C# 压缩代码 #

FileInfo fileToBeGZipped = new FileInfo(filePath);
FileInfo gzipFileName = new FileInfo(string.Concat(fileToBeGZipped.FullName, ".gzip"));

using (FileStream fileToBeZippedAsStream = fileToBeGZipped.OpenRead())
{
    using (FileStream gzipTargetAsStream = gzipFileName.Create())
    {
        using (GZipStream gzipStream = new GZipStream(gzipTargetAsStream, CompressionMode.Compress))
        {
            try
            {
                fileToBeZippedAsStream.CopyTo(gzipStream);                                
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
        }
    }
}

iOS 解压代码 #

if (![SSZipArchive unzipFileAtPath:[downloadedStoreURL path] toDestination:[destinationURL path] delegate:nil]) {
    CLHLog(@"Couldn't unzip downloaded database");
    return NO;
}

错误信息 #

Error listing contents of archive: Error Domain=UZKErrorDomain Code=-103 "Bad zip file" UserInfo={NSLocalizedFailureReason=Bad zip file, NSLocalizedRecoverySuggestion=Error opening zip file /var/mobile/Containers/Data/Application/1DD4F888-0171-42D0-AC69-E0D497AC3943/Library/InspectionForms_compresed.sqlite.gzip, NSURL=file:///var/mobile/Containers/Data/Application/1DD4F888-0171-42D0-AC69-E0D497AC3943/Library/InspectionForms_compresed.sqlite.gzip, NSLocalizedDescription=Bad zip file}

解决方案 #

这个问题不需要额外编码处理，核心矛盾是格式适配问题：

1. SSZipArchive的定位是处理ZIP格式，而非GZIP
   GZip和Zip是两种完全不同的压缩标准：

   • 你的C#代码生成的是单文件GZIP压缩包，属于流式压缩格式
   • SSZipArchive主打多文件ZIP归档解压，Mac端环境对GZIP的兼容逻辑更宽松，iOS端的底层实现则对非ZIP格式的识别存在限制，因此报错。

2. 直接解决方案：iOS端换用GZIP专用解压逻辑
   放弃用SSZipArchive处理GZIP文件，改用iOS原生zlib库实现解压，比如封装NSData的扩展方法：

   #import <zlib.h>
   
   @interface NSData (GZIP)
   - (NSData *)gzipInflate;
   @end
   
   @implementation NSData (GZIP)
   - (NSData *)gzipInflate {
       if ([self length] == 0) return self;
   
       unsigned full_length = [self length];
       unsigned half_length = [self length] / 2;
   
       NSMutableData *decompressed = [NSMutableData dataWithLength: full_length + half_length];
       BOOL done = NO;
       int status;
   
       z_stream strm;
       strm.next_in = (Bytef *)[self bytes];
       strm.avail_in = [self length];
       strm.total_out = 0;
       strm.zalloc = Z_NULL;
       strm.zfree = Z_NULL;
   
       if (inflateInit2(&strm, (15+32)) != Z_OK) return nil;
       while (!done) {
           if (strm.total_out >= [decompressed length])
               [decompressed increaseLengthBy: half_length];
   
           strm.next_out = [decompressed mutableBytes] + strm.total_out;
           strm.avail_out = [decompressed length] - strm.total_out;
   
           status = inflate (&strm, Z_NO_FLUSH);
           if (status == Z_STREAM_END) done = YES;
           else if (status != Z_OK) break;
       }
       if (inflateEnd (&strm) != Z_OK) return nil;
   
       if (done) {
           [decompressed setLength: strm.total_out];
           return decompressed;
       } else return nil;
   }
   @end
   

   调用示例：

   NSData *gzipData = [NSData dataWithContentsOfURL:downloadedStoreURL];
   NSData *uncompressedData = [gzipData gzipInflate];
   if (uncompressedData) {
       [uncompressedData writeToURL:destinationURL atomically:YES];
   } else {
       CLHLog(@"Couldn't unzip downloaded database");
       return NO;
   }
   

3. 备选方案：C#端生成ZIP格式文件
   如果坚持要用SSZipArchive，可修改C#代码生成标准ZIP包：

   using (FileStream zipToOpen = new FileInfo("output.zip").Create())
   {
       using (ZipArchive archive = new ZipArchive(zipToOpen, ZipArchiveMode.Create))
       {
           ZipArchiveEntry entry = archive.CreateEntry("InspectionForms_compresed.sqlite");
           using (FileStream fileStream = new FileInfo(filePath).OpenRead())
           using (Stream entryStream = entry.Open())
           {
               fileStream.CopyTo(entryStream);
           }
       }
   }
   

   这样iOS端用现有SSZipArchive代码即可正常解压。

内容的提问来源于stack exchange，提问作者ramdev