4 files changed, 37 insertions, 20 deletions
diff --git a/src/gui/updatewindow.cpp b/src/gui/updatewindow.cpp
index 132f8bcfc..f4281cff1 100644
--- a/src/gui/updatewindow.cpp
+++ b/src/gui/updatewindow.cpp
@@ -635,7 +635,8 @@ void UpdaterWindow::logic()
                     std::ifstream temp(
                             (mUpdatesDir + "/" + mCurrentFile).c_str());
 
-                    if (!temp.is_open())
+                    if (!temp.is_open() || !validateFile(mUpdatesDir + "/"
+                        + mCurrentFile, mCurrentChecksum))
                     {
                         temp.close();
                         download();
@@ -671,3 +672,14 @@ void UpdaterWindow::logic()
             break;
     }
 }
+
+bool UpdaterWindow::validateFile(std::string filePath, long hash)
+{
+    FILE *file = fopen(filePath.c_str(), "rb");
+    if (!file)
+        return false;
+
+    unsigned long adler = Net::Download::fadler32(file);
+    fclose(file);
+    return adler == hash;
+}
diff --git a/src/gui/updatewindow.h b/src/gui/updatewindow.h
index 1246c9b35..13b72f3a8 100644
--- a/src/gui/updatewindow.h
+++ b/src/gui/updatewindow.h
@@ -136,6 +136,8 @@ private:
     static size_t memoryWrite(void *ptr, size_t size, size_t nmemb,
                               void *stream);
 
+    bool validateFile(std::string filePath, long hash);
+
     enum UpdateDownloadStatus
     {
         UPDATE_ERROR = 0,
diff --git a/src/net/download.cpp b/src/net/download.cpp
index 95dfcd298..40d7c872a 100644
--- a/src/net/download.cpp
+++ b/src/net/download.cpp
@@ -37,25 +37,6 @@
 const char *DOWNLOAD_ERROR_MESSAGE_THREAD
     = "Could not create download thread!";
 
-/**
- * Calculates the Alder-32 checksum for the given file.
- */
-static unsigned long fadler32(FILE *file)
-{
-    // Obtain file size
-    fseek(file, 0, SEEK_END);
-    long fileSize = ftell(file);
-    rewind(file);
-
-    // Calculate Adler-32 checksum
-    char *buffer = static_cast<char*>(malloc(fileSize));
-    const size_t read = fread(buffer, 1, fileSize, file);
-    unsigned long adler = adler32(0L, Z_NULL, 0);
-    adler = adler32(static_cast<uInt>(adler), (Bytef*)buffer, read);
-    free(buffer);
-
-    return adler;
-}
 
 enum
 {
@@ -97,6 +78,26 @@ Download::~Download()
     free(mError);
 }
 
+/**
+ * Calculates the Alder-32 checksum for the given file.
+ */
+unsigned long Download::fadler32(FILE *file)
+{
+    // Obtain file size
+    fseek(file, 0, SEEK_END);
+    long fileSize = ftell(file);
+    rewind(file);
+
+    // Calculate Adler-32 checksum
+    char *buffer = static_cast<char*>(malloc(fileSize));
+    const size_t read = fread(buffer, 1, fileSize, file);
+    unsigned long adler = adler32(0L, Z_NULL, 0);
+    adler = adler32(static_cast<uInt>(adler), (Bytef*)buffer, read);
+    free(buffer);
+
+    return adler;
+}
+
 void Download::addHeader(const std::string &header)
 {
     mHeaders = curl_slist_append(mHeaders, header.c_str());
diff --git a/src/net/download.h b/src/net/download.h
index bb931bb15..71bb41cee 100644
--- a/src/net/download.h
+++ b/src/net/download.h
@@ -95,6 +95,8 @@ class Download
         void setIgnoreError(bool n)
         { mIgnoreError = n; }
 
+        static unsigned long fadler32(FILE *file);
+
     private:
         static int downloadThread(void *ptr);
         static int downloadProgress(void *clientp, double dltotal,