[analyzer] exploded-graph-rewriter: Fix python3 string encoding issues

[steakhal]

Summary

This encapsulates 3 changes:

• DotDumpVisitor now aggregates strings instead of bytes for both python2 and python3. This difference caused crashes when it tried to write out the content as strings, similarly described at D71746.
• graphviz.pipe() expects the input in *bytes* instead of unicode strings. And it results in bytes. Due to string concatenations and similar operations, I'm using unicode string as the default and converting to bytes on demand.
• write_temp_file() now appends the egraph- prefix and more importantly, it will create the temp file in the current working directory instead of in the temp. This change makes Firefox be able to open the file even if the security.sandbox.content.level is set to the (default) most restricting 4. See https://support.mozilla.org/si/questions/1259285

An artifact of the bad byte handling was previously in the HTML
produced by the script that it displayed the b' string at the top left
corner. Now it won't anymore :)

I've tested that the following command works on Ubuntu 22.04:

exploded-graph-rewriter my-egraph.dot

Both python2 and python3 works as expected.

---

PS: I'm not adding tests, as the current test infra does not support
testing HTML outputs for this script.
Check the clang/test/Analysis/exploded-graph-rewriter/lit.local.cfg.
We always pass the --dump-dot-only flag to the script.
Along with that, the default invocation will not only create this HTML
report but also try to open it. In addition to this, I'm not sure if the
buildbots have graphviz installed and also if this package is installed
on pip.
Unless we change some of these, we cannot test this change.
Given that D71746 had no tests, I'm not too worried about this either.

[NoQ]

Thanks for figuring all of this out! Looks great!

That's right, we can't and probably shouldn't test graphviz.

clang/utils/analyzer/exploded-graph-rewriter.py

862

I think the reminder is still relevant. These files can be like 100mb in size, and now that they aren't in /tmp they aren't autocleaned.

clang/utils/analyzer/exploded-graph-rewriter.py

 
 import argparse
 import collections
 import difflib
 import json
 import logging
 import os
 import re
-import sys
 
 
 #===-----------------------------------------------------------------------===#
 # These data structures represent a deserialized ExplodedGraph.
 #===-----------------------------------------------------------------------===#
 
 
 # A helper function for finding the difference between two dictionaries.
class DotDumpVisitor:
     def _dump_raw(self, s):
         if self._dump_dot_only:
             print(s, end='')
         else:
             self._output.append(s)
 
     def output(self):
         assert not self._dump_dot_only
-        if sys.version_info[0] > 2 and sys.version_info[1] >= 5:
-            return ''.join(self._output).encode()
-        else:
-            return ''.join(self._output)
 
     def _dump(self, s):
         s = s.replace('&', '&') \
              .replace('{', '\\{') \
              .replace('}', '\\}') \
              .replace('\\<', '&lt;') \
              .replace('\\>', '&gt;') \
              .replace('|', '\\|')
class DotDumpVisitor:
 
     def visit_end_of_graph(self):
         self._dump_raw('}\n')
 
         if not self._dump_dot_only:
             import sys
             import tempfile
 
-            def write_temp_file(suffix, data):
-                fd, filename = tempfile.mkstemp(suffix=suffix)
+            def write_temp_file(suffix, prefix, data):
+                fd, filename = tempfile.mkstemp(suffix, prefix, '.', True)
                 print('Writing "%s"...' % filename)
                 with os.fdopen(fd, 'w') as fp:
                     fp.write(data)
                 print('Done! Please remember to remove the file.')
                 return filename
 
             try:
                 import graphviz
             except ImportError:
                 # The fallback behavior if graphviz is not installed!
                 print('Python graphviz not found. Please invoke')
                 print('  $ pip install graphviz')
                 print('in order to enable automatic conversion to HTML.')
                 print()
                 print('You may also convert DOT to SVG manually via')
                 print('  $ dot -Tsvg input.dot -o output.svg')
                 print()
-                write_temp_file('.dot', self.output())
+                write_temp_file('.dot', 'egraph-', self.output())
                 return
 
-            svg = graphviz.pipe('dot', 'svg', self.output())
+            svg = graphviz.pipe('dot', 'svg', self.output().encode()).decode()
 
             filename = write_temp_file(
-                '.html', '<html><body bgcolor="%s">%s</body></html>' % (
+                '.html', 'egraph-', '<html><body bgcolor="%s">%s</body></html>' % (
                              '#1a1a1a' if self._dark_mode else 'white', svg))
             if sys.platform == 'win32':
                 os.startfile(filename)
             elif sys.platform == 'darwin':
                 os.system('open "%s"' % filename)
             else:
                 os.system('xdg-open "%s"' % filename)