Backported file open crash fixes for Issue #430 to python2 branch

Also:
- Bumped version on python2 branch to 0.8.8
- Updated CHANGELOG

Author: tleonhardt

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.8.8 (TBD, 2018)
+* Bug Fixes
+    * Prevent crashes that could occur attempting to open a file in non-existent directory or with very long filename
+
 ## 0.8.7 (May 28, 2018)
 * Bug Fixes
     * Make sure pip installs version 0.8.x if you have python 2.7

cmd2.py

@@ -229,7 +229,7 @@ def pyreadline_remove_history_item(pos):
         pass
 
 
-__version__ = '0.8.7'
+__version__ = '0.8.8'
 
 # Pyparsing enablePackrat() can greatly speed up parsing, but problems have been seen in Python 3 in the past
 pyparsing.ParserElement.enablePackrat()
@@ -2470,7 +2470,7 @@ def onecmd_plus_hooks(self, line):
                 if self.timing:
                     self.pfeedback('Elapsed: %s' % str(datetime.datetime.now() - timestart))
             finally:
-                if self.allow_redirection:
+                if self.allow_redirection and self.redirecting:
                     self._restore_output(statement)
         except EmptyStatement:
             pass
@@ -2586,7 +2586,11 @@ def _redirect_output(self, statement):
                 mode = 'w'
                 if statement.parsed.output == 2 * self.redirector:
                     mode = 'a'
-                sys.stdout = self.stdout = open(os.path.expanduser(statement.parsed.outputTo), mode)
+                try:
+                    sys.stdout = self.stdout = open(os.path.expanduser(statement.parsed.outputTo), mode)
+                except (FILE_NOT_FOUND_ERROR, IOError) as ex:
+                    self.perror('Not Redirecting because - {}'.format(ex), traceback_war=False)
+                    self.redirecting = False
             else:
                 sys.stdout = self.stdout = tempfile.TemporaryFile(mode="w+")
                 if statement.parsed.output == '>>':
@@ -3638,34 +3642,7 @@ def do_history(self, args):
             except Exception as e:
                 self.perror('Saving {!r} - {}'.format(args.output_file, e), traceback_war=False)
         elif args.transcript:
-            # Make sure echo is on so commands print to standard out
-            saved_echo = self.echo
-            self.echo = True
-
-            # Redirect stdout to the transcript file
-            saved_self_stdout = self.stdout
-            self.stdout = open(args.transcript, 'w')
-
-            # Run all of the commands in the history with output redirected to transcript and echo on
-            self.runcmds_plus_hooks(history)
-
-            # Restore stdout to its original state
-            self.stdout.close()
-            self.stdout = saved_self_stdout
-
-            # Set echo back to its original state
-            self.echo = saved_echo
-
-            # Post-process the file to escape un-escaped "/" regex escapes
-            with open(args.transcript, 'r') as fin:
-                data = fin.read()
-            post_processed_data = data.replace('/', '\/')
-            with open(args.transcript, 'w') as fout:
-                fout.write(post_processed_data)
-
-            plural = 's' if len(history) > 1 else ''
-            self.pfeedback('{} command{} and outputs saved to transcript file {!r}'.format(len(history), plural,
-                                                                                           args.transcript))
+            self._generate_transcript(history, args.transcript)
         else:
             # Display the history items retrieved
             for hi in history:
@@ -3674,6 +3651,73 @@ def do_history(self, args):
                 else:
                     self.poutput(hi.pr())
 
+    def _generate_transcript(self, history, transcript_file):
+        """Generate a transcript file from a given history of commands."""
+        # Save the current echo state, and turn it off. We inject commands into the
+        # output using a different mechanism
+        import io
+
+        saved_echo = self.echo
+        self.echo = False
+
+        # Redirect stdout to the transcript file
+        saved_self_stdout = self.stdout
+
+        # The problem with supporting regular expressions in transcripts
+        # is that they shouldn't be processed in the command, just the output.
+        # In addition, when we generate a transcript, any slashes in the output
+        # are not really intended to indicate regular expressions, so they should
+        # be escaped.
+        #
+        # We have to jump through some hoops here in order to catch the commands
+        # separately from the output and escape the slashes in the output.
+        transcript = ''
+        for history_item in history:
+            # build the command, complete with prompts. When we replay
+            # the transcript, we look for the prompts to separate
+            # the command from the output
+            first = True
+            command = ''
+            for line in history_item.splitlines():
+                if first:
+                    command += '{}{}\n'.format(self.prompt, line)
+                    first = False
+                else:
+                    command += '{}{}\n'.format(self.continuation_prompt, line)
+            transcript += command
+            # create a new string buffer and set it to stdout to catch the output
+            # of the command
+            membuf = io.StringIO()
+            self.stdout = membuf
+            # then run the command and let the output go into our buffer
+            self.onecmd_plus_hooks(history_item)
+            # rewind the buffer to the beginning
+            membuf.seek(0)
+            # get the output out of the buffer
+            output = membuf.read()
+            # and add the regex-escaped output to the transcript
+            transcript += output.replace('/', '\/')
+
+        # Restore stdout to its original state
+        self.stdout = saved_self_stdout
+        # Set echo back to its original state
+        self.echo = saved_echo
+
+        # finally, we can write the transcript out to the file
+        try:
+            with open(transcript_file, 'w') as fout:
+                fout.write(transcript)
+        except (FILE_NOT_FOUND_ERROR, IOError) as ex:
+            self.perror('Failed to save transcript: {}'.format(ex), traceback_war=False)
+        else:
+            # and let the user know what we did
+            if len(history) > 1:
+                plural = 'commands and their outputs'
+            else:
+                plural = 'command and its output'
+            msg = '{} {} saved to transcript file {!r}'
+            self.pfeedback(msg.format(len(history), plural, transcript_file))
+
     @with_argument_list
     def do_edit(self, arglist):
         """Edit a file in a text editor.

docs/conf.py

@@ -62,7 +62,7 @@
 # The short X.Y version.
 version = '0.8'
 # The full version, including alpha/beta/rc tags.
-release = '0.8.7'
+release = '0.8.8'
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.

setup.py

@@ -8,7 +8,7 @@
 import setuptools
 from setuptools import setup
 
-VERSION = '0.8.7'
+VERSION = '0.8.8'
 DESCRIPTION = "cmd2 - a tool for building interactive command line applications in Python"
 LONG_DESCRIPTION = """cmd2 is a tool for building interactive command line applications in Python. Its goal is to make
 it quick and easy for developers to build feature-rich and user-friendly interactive command line applications.  It

tests/test_cmd2.py

@@ -26,7 +26,7 @@
 
 
 def test_ver():
-    assert cmd2.__version__ == '0.8.7'
+    assert cmd2.__version__ == '0.8.8'
 
 
 def test_empty_statement(base_app):
@@ -553,6 +553,44 @@ def test_output_redirection(base_app):
     finally:
         os.remove(filename)
 
+def test_output_redirection_to_nonexistent_directory(base_app):
+    filename = '~/fakedir/this_does_not_exist.txt'
+
+    # Verify that writing to a file in a non-existent directory doesn't work
+    run_cmd(base_app, 'help > {}'.format(filename))
+    expected = normalize(BASE_HELP)
+    with pytest.raises(cmd2.FILE_NOT_FOUND_ERROR):
+        with open(filename) as f:
+            content = normalize(f.read())
+        assert content == expected
+
+    # Verify that appending to a file also works
+    run_cmd(base_app, 'help history >> {}'.format(filename))
+    expected = normalize(BASE_HELP + '\n' + HELP_HISTORY)
+    with pytest.raises(cmd2.FILE_NOT_FOUND_ERROR):
+        with open(filename) as f:
+            content = normalize(f.read())
+        assert content == expected
+
+def test_output_redirection_to_too_long_filename(base_app):
+    filename = '~/sdkfhksdjfhkjdshfkjsdhfkjsdhfkjdshfkjdshfkjshdfkhdsfkjhewfuihewiufhweiufhiweufhiuewhiuewhfiuwehfiuewhfiuewhfiuewhfiuewhiuewhfiuewhfiuewfhiuwehewiufhewiuhfiweuhfiuwehfiuewfhiuwehiuewfhiuewhiewuhfiuewhfiuwefhewiuhewiufhewiufhewiufhewiufhewiufhewiufhewiufhewiuhewiufhewiufhewiuheiufhiuewheiwufhewiufheiufheiufhieuwhfewiuhfeiufhiuewfhiuewheiwuhfiuewhfiuewhfeiuwfhewiufhiuewhiuewhfeiuwhfiuwehfuiwehfiuehiuewhfieuwfhieufhiuewhfeiuwfhiuefhueiwhfw'
+
+    # Verify that writing to a file in a non-existent directory doesn't work
+    run_cmd(base_app, 'help > {}'.format(filename))
+    expected = normalize(BASE_HELP)
+    with pytest.raises(IOError):
+        with open(filename) as f:
+            content = normalize(f.read())
+        assert content == expected
+
+    # Verify that appending to a file also works
+    run_cmd(base_app, 'help history >> {}'.format(filename))
+    expected = normalize(BASE_HELP + '\n' + HELP_HISTORY)
+    with pytest.raises(IOError):
+        with open(filename) as f:
+            content = normalize(f.read())
+        assert content == expected
+
 
 def test_feedback_to_output_true(base_app):
     base_app.feedback_to_output = True

tests/test_transcript.py

@@ -14,6 +14,7 @@
 import pytest
 import six
 
+import cmd2
 from cmd2 import (Cmd, options, Cmd2TestCase, set_use_arg_list,
                   set_posix_shlex, set_strip_quotes)
 from conftest import run_cmd, StdOut, normalize
@@ -305,6 +306,32 @@ def test_transcript(request, capsys, filename, feedback_to_output):
         assert out == ''
 
 
+def test_history_transcript_bad_filename(request, capsys):
+    app = CmdLineApp()
+    app.stdout = StdOut()
+    run_cmd(app, 'orate this is\na /multiline/\ncommand;\n')
+    run_cmd(app, 'speak /tmp/file.txt is not a regex')
+
+    expected = r"""(Cmd) orate this is
+> a /multiline/
+> command;
+this is a \/multiline\/ command
+(Cmd) speak /tmp/file.txt is not a regex
+\/tmp\/file.txt is not a regex
+"""
+
+    # make a tmp file
+    history_fname = '~/fakedir/this_does_not_exist.txt'
+
+    # tell the history command to create a transcript
+    run_cmd(app, 'history -t "{}"'.format(history_fname))
+
+    # read in the transcript created by the history command
+    with pytest.raises(cmd2.FILE_NOT_FOUND_ERROR):
+        with open(history_fname) as f:
+            transcript = f.read()
+        assert transcript == expected
+
 @pytest.mark.parametrize('expected, transformed', [
     # strings with zero or one slash or with escaped slashes means no regular
     # expression present, so the result should just be what re.escape returns.