SF bug 797650: Infinite loop in textwrap.py

When the indents were set to longer than the width and long word breaking
was enabled, an infinite loop would result because the inner loop did not
assure that at least one character was stripped off on every pass.

2 files changed, 11 insertions, 1 deletions

diff --git a/Lib/test/test_textwrap.py b/Lib/test/test_textwrap.py
index 904c790..a011168 100644
--- a/Lib/test/test_textwrap.py
+++ b/Lib/test/test_textwrap.py
@@ -305,6 +305,16 @@ How *do* you spell that odd word, anyways?
                         ['Did you say "supercalifragilisticexpialidocious?"',
                          'How *do* you spell that odd word, anyways?'])
 
+        # SF bug 797650.  Prevent an infinite loop by making sure that at
+        # least one character gets split off on every pass.
+        self.check_wrap('-'*10+'hello', 10,
+                        ['----------',
+                         '               h',
+                         '               e',
+                         '               l',
+                         '               l',
+                         '               o'],
+                        subsequent_indent = ' '*15)
 
     def test_nobreak_long(self):
         # Test with break_long_words disabled
diff --git a/Lib/textwrap.py b/Lib/textwrap.py
index a4a5498..f371fbb 100644
--- a/Lib/textwrap.py
+++ b/Lib/textwrap.py
@@ -168,7 +168,7 @@ class TextWrapper:
         Handle a chunk of text (most likely a word, not whitespace) that
         is too long to fit in any line.
         """
-        space_left = width - cur_len
+        space_left = max(width - cur_len, 1)
 
         # If we're allowed to break long words, then do so: put as much
         # of the next chunk onto the current line as will fit.