Add fwrite() and uncompressed_size validation

Author: Shinichiro Oba

Zip/Zip.swift

@@ -180,12 +180,17 @@ public class Zip {
                 unzCloseCurrentFile(zip)
                 ret = unzGoToNextFile(zip)
             }
+
+            var writeBytes: UInt64 = 0
             var filePointer: UnsafeMutablePointer<FILE>?
             filePointer = fopen(fullPath, "wb")
             while filePointer != nil {
                 let readBytes = unzReadCurrentFile(zip, &buffer, bufferSize)
                 if readBytes > 0 {
-                    fwrite(buffer, Int(readBytes), 1, filePointer)
+                    guard fwrite(buffer, Int(readBytes), 1, filePointer) == 1 else {
+                        throw ZipError.unzipFail
+                    }
+                    writeBytes += UInt64(readBytes)
                 }
                 else {
                     break
@@ -197,6 +202,9 @@ public class Zip {
             if crc_ret == UNZ_CRCERROR {
                 throw ZipError.unzipFail
             }
+            guard writeBytes == fileInfo.uncompressed_size else {
+                throw ZipError.unzipFail
+            }
 
             //Set file permissions from current fileInfo
             if fileInfo.external_fa != 0 {