Issue #7384: If the system readline library is linked against ncurses,

the curses module must be linked against ncurses as well. Otherwise it
is not safe to load both the readline and curses modules in an application.

Thanks Thomas Dickey for answering questions about ncurses/ncursesw
and readline!

3 files changed, 41 insertions, 24 deletions

diff --git a/Lib/test/test_curses.py b/Lib/test/test_curses.py
index 69271de847..18d73fc79e 100644
--- a/Lib/test/test_curses.py
+++ b/Lib/test/test_curses.py
@@ -21,11 +21,6 @@ requires('curses')
 curses = import_module('curses')
 curses.panel = import_module('curses.panel')
 
-# skip all these tests on FreeBSD: test_curses currently hangs the
-# FreeBSD buildbots, preventing other tests from running.  See issue
-# #7384.
-if 'freebsd' in sys.platform:
-    raise unittest.SkipTest('The curses module is broken on FreeBSD.  See http://bugs.python.org/issue7384.')
 
 # XXX: if newterm was supported we could use it instead of initscr and not exit
 term = os.environ.get('TERM')
diff --git a/Misc/NEWS b/Misc/NEWS
index 9debe2cdc2..25b265b6c6 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -89,6 +89,10 @@ Library
 Extension Modules
 -----------------
 
+- Issue #7384: If the system readline library is linked against ncurses,
+  the curses module must be linked against ncurses as well. Otherwise it
+  is not safe to load both the readline and curses modules in an application.
+
 - Issue #2810: Fix cases where the Windows registry API returns
   ERROR_MORE_DATA, requiring a re-try in order to get the complete result.
 
diff --git a/setup.py b/setup.py
index 7294a1614c..cb65f46e34 100644
--- a/setup.py
+++ b/setup.py
@@ -588,6 +588,32 @@ class PyBuildExt(build_ext):
 
         # readline
         do_readline = self.compiler.find_library_file(lib_dirs, 'readline')
+        readline_termcap_library = ""
+        curses_library = ""
+        # Determine if readline is already linked against curses or tinfo.
+        if do_readline and platform != 'darwin': # OS X does not have ldd.
+            fp = os.popen("ldd %s" % do_readline)
+            for ln in fp:
+                if 'curses' in ln:
+                    readline_termcap_library = re.sub(
+                        r'.*lib(n?cursesw?)\.so.*', r'\1', ln
+                    ).rstrip()
+                    break
+                if 'tinfo' in ln: # termcap interface split out from ncurses
+                    readline_termcap_library = 'tinfo'
+                    break
+            fp.close()
+        # Issue 7384: If readline is already linked against curses,
+        # use the same library for the readline and curses modules.
+        if 'curses' in readline_termcap_library:
+            curses_library = readline_termcap_library
+        elif self.compiler_obj.find_library_file(lib_dirs, 'ncursesw'):
+            curses_library = 'ncursesw'
+        elif self.compiler_obj.find_library_file(lib_dirs, 'ncurses'):
+            curses_library = 'ncurses'
+        elif self.compiler_obj.find_library_file(lib_dirs, 'curses'):
+            curses_library = 'curses'
+
         if platform == 'darwin':
             os_release = int(os.uname()[2].split('.')[0])
             dep_target = sysconfig.get_config_var('MACOSX_DEPLOYMENT_TARGET')
@@ -611,14 +637,10 @@ class PyBuildExt(build_ext):
                 readline_extra_link_args = ()
 
             readline_libs = ['readline']
-            if self.compiler.find_library_file(lib_dirs,
-                                                   'ncursesw'):
-                readline_libs.append('ncursesw')
-            elif self.compiler.find_library_file(lib_dirs,
-                                                     'ncurses'):
-                readline_libs.append('ncurses')
-            elif self.compiler.find_library_file(lib_dirs, 'curses'):
-                readline_libs.append('curses')
+            if readline_termcap_library:
+                pass # Issue 7384: Already linked against curses or tinfo.
+            elif curses_library:
+                readline_libs.append(curses_library)
             elif self.compiler.find_library_file(lib_dirs +
                                                      ['/usr/lib/termcap'],
                                                      'termcap'):
@@ -1187,19 +1209,15 @@ class PyBuildExt(build_ext):
         # Curses support, requiring the System V version of curses, often
         # provided by the ncurses library.
         panel_library = 'panel'
-        if (self.compiler.find_library_file(lib_dirs, 'ncursesw')):
-            curses_libs = ['ncursesw']
-            # Bug 1464056: If _curses.so links with ncursesw,
-            # _curses_panel.so must link with panelw.
-            panel_library = 'panelw'
-            exts.append( Extension('_curses', ['_cursesmodule.c'],
-                                   libraries = curses_libs) )
-        elif (self.compiler.find_library_file(lib_dirs, 'ncurses')):
-            curses_libs = ['ncurses']
+        if curses_library.startswith('ncurses'):
+            if curses_library == 'ncursesw':
+                # Bug 1464056: If _curses.so links with ncursesw,
+                # _curses_panel.so must link with panelw.
+                panel_library = 'panelw'
+            curses_libs = [curses_library]
             exts.append( Extension('_curses', ['_cursesmodule.c'],
                                    libraries = curses_libs) )
-        elif (self.compiler.find_library_file(lib_dirs, 'curses')
-              and platform != 'darwin'):
+        elif curses_library == 'curses' and platform != 'darwin':
                 # OSX has an old Berkeley curses, not good enough for
                 # the _curses module.
             if (self.compiler.find_library_file(lib_dirs, 'terminfo')):