[LNT] Python 3 support: fix writing report to tmp file

[thopre]

Summary

The import_from_string() method in lnt.util.ImportData writes a copy of
the report being imported into a temporary file. That fails under Python
3 because by default tempfile.mkstemp open in binary mode and the data
written is text.

This commit sets the text parameter of mkstemp to True to ensure the
file is opened in text mode. It also write to the file via a file object
since os.write expects binary data.

[PrzemekWirkus]

lnt/util/ImportData.py

341–343

This can be simplified to:

with os.fdopen(fd, "w") as fp:

fp.write(data)

?

[thopre]

Committed as 709b097e686ee0182e343fdb89242a319c9a8303

[PrzemekWirkus]

lnt/util/ImportData.py

341–343

Got that code block wrong last time:

with os.fdopen(fd, "w") as fp:
    fp.write(data)

[thopre]

lnt/util/ImportData.py

341–343

Sorry, only saw that after committing the change. I've created https://reviews.llvm.org/D71058 for it

lnt/util/ImportData.py

def import_from_string(config, db_name, db, session, ts_name, data,
     except OSError:
         pass
 
     # Save the file under a name prefixed with the date, to make it easier
     # to use these files in cases we might need them for debugging or data
     # recovery.
     prefix = utcnow.strftime("data-%Y-%m-%d_%H-%M-%S")
     fd, path = tempfile.mkstemp(prefix=prefix, suffix='.json',
-                                dir=str(tmpdir))
-    os.write(fd, data)
-    os.close(fd)
+                                dir=str(tmpdir), text=True)
+    fp = os.fdopen(fd, "w")
+    fp.write(data)
+    fp.close()
 
     # Import the data.
     #
     # FIXME: Gracefully handle formats failures and DOS attempts. We
     # should at least reject overly large inputs.
 
     result = lnt.util.ImportData.import_and_report(
         config, db_name, db, session, path, '<auto>', ts_name,
         select_machine=select_machine, merge_run=merge_run)
     return result