Fixed bug when handling same input and output file

HISTORY.rst

@@ -1,6 +1,10 @@
 History
 ===============
 
+0.4.2 (Sep 2018)
+~~~~~~~~~~~~~~~~~~
+* Fixed bug when handling same input and output file 
+
 0.4.1 (Sep 2018)
 ~~~~~~~~~~~~~~~~~~
 * Preventing users from specifying the same input and output file 

pyAesCrypt/crypto.py

@@ -43,7 +43,7 @@
 from os import stat, remove, path
 
 # pyAesCrypt version
-version = "0.4.1"
+version = "0.4.2"
 
 # encryption/decryption buffer size - 64K
 bufferSize = 64 * 1024
@@ -81,12 +81,15 @@ def stretch(passw, iv1):
 def encryptFile(infile, outfile, passw, bufferSize):
     try:
         with open(infile, "rb") as fIn:
+            # check that output file does not exist
+            # or that, if exists, is not the same as the input file
+            # (i.e.: overwrite if it seems safe)
+            if path.isfile(outfile):
+                if path.samefile(infile, outfile):
+                    raise ValueError("Input and output files "
+                                     "are the same.")
             try:
                 with open(outfile, "wb") as fOut:
-                    # check if input and output files are the same
-                    if path.samefile(infile, outfile):
-                        raise ValueError("Input and output files "
-                                         "are the same.")
                     # encrypt file stream
                     encryptStream(fIn, fOut, passw, bufferSize)
 
@@ -244,12 +247,15 @@ def encryptStream(fIn, fOut, passw, bufferSize):
 def decryptFile(infile, outfile, passw, bufferSize):
     try:
         with open(infile, "rb") as fIn:
+            # check that output file does not exist
+            # or that, if exists, is not the same as the input file
+            # (i.e.: overwrite if it seems safe)
+            if path.isfile(outfile):
+                if path.samefile(infile, outfile):
+                    raise ValueError("Input and output files "
+                                     "are the same.")
             try:
                 with open(outfile, "wb") as fOut:
-                    # check if input and output files are the same
-                    if path.samefile(infile, outfile):
-                        raise ValueError("Input and output files "
-                                         "are the same.")
                     # get input file size
                     inputFileSize = stat(infile).st_size
                     try:

pyAesCrypt/test_crypto.py

@@ -201,7 +201,10 @@ def test_bs_quick(self):
 class TestExceptions(unittest.TestCase):
 
     # test file path
-    tfile = prefix+'test.txt'
+    tfile = prefix + 'test.txt'
+
+    # path of the copy of the test file
+    tfilebak = tfile + '.bak'
 
     # fixture for preparing the environment
     def setUp(self):
@@ -216,6 +219,8 @@ def setUp(self):
         # generate a test file
         with open(self.tfile, 'wb') as fout:
             fout.write(os.urandom(4))
+        # copy of the test file
+        shutil.copyfile(self.tfile, self.tfilebak)
 
     def tearDown(self):
         # remove whole directory tree
@@ -327,13 +332,17 @@ def test_samefile_enc(self):
                                pyAesCrypt.encryptFile,
                                self.tfile, self.tfile,
                                'pass', bufferSize)
+        # check that the original file was not modified
+        self.assertTrue(filecmp.cmp(self.tfile, self.tfilebak))
     # test same input and output file - decryption
     def test_samefile_dec(self):
         self.assertRaisesRegex(ValueError, ("Input and output files "
                                             "are the same."),
                                pyAesCrypt.decryptFile,
                                self.tfile, self.tfile,
                                'pass', bufferSize)
+        # check that the original file was not modified
+        self.assertTrue(filecmp.cmp(self.tfile, self.tfilebak))
 
 if __name__ == '__main__':
     unittest.main()

setup.py

@@ -5,7 +5,7 @@
     README = readme.read()
 
 setup(name='pyAesCrypt',
-    version='0.4.1',
+    version='0.4.2',
     packages = find_packages(),
     include_package_data=True,
     description='Encrypt and decrypt files and streams in AES Crypt format (version 2)',