Issue #19308: fix the gdb plugin on gdbs linked with Python 3

Lib/test/test_gdb.py

@@ -59,7 +59,7 @@ def run_gdb(*args, **env_vars):
     return out.decode('utf-8', 'replace'), err.decode('utf-8', 'replace')
 
 # Verify that "gdb" was built with the embedded python support enabled:
-gdbpy_version, _ = run_gdb("--eval-command=python import sys; print sys.version_info")
+gdbpy_version, _ = run_gdb("--eval-command=python import sys; print(sys.version_info)")
 if not gdbpy_version:
     raise unittest.SkipTest("gdb not built with embedded python support")
 

Tools/gdb/libpython.py

@@ -40,11 +40,21 @@ the type names are known to the debugger
 
 The module also extends gdb with some python-specific commands.
 '''
-from __future__ import with_statement
+
+# NOTE: some gdbs are linked with Python 3, so this file should be dual-syntax
+# compatible (2.6+ and 3.0+).  See #19308.
+
+from __future__ import print_function, with_statement
 import gdb
+import os
 import locale
 import sys
 
+if sys.version_info[0] >= 3:
+    unichr = chr
+    xrange = range
+    long = int
+
 # Look up the gdb.Type for some standard types:
 _type_char_ptr = gdb.lookup_type('char').pointer() # char*
 _type_unsigned_char_ptr = gdb.lookup_type('unsigned char').pointer() # unsigned char*
@@ -58,16 +68,16 @@ _is_pep393 = None
 SIZEOF_VOID_P = _type_void_ptr.sizeof
 
 
-Py_TPFLAGS_HEAPTYPE = (1L << 9)
+Py_TPFLAGS_HEAPTYPE = (1 << 9)
 
-Py_TPFLAGS_LONG_SUBCLASS     = (1L << 24)
-Py_TPFLAGS_LIST_SUBCLASS     = (1L << 25)
-Py_TPFLAGS_TUPLE_SUBCLASS    = (1L << 26)
-Py_TPFLAGS_BYTES_SUBCLASS    = (1L << 27)
-Py_TPFLAGS_UNICODE_SUBCLASS  = (1L << 28)
-Py_TPFLAGS_DICT_SUBCLASS     = (1L << 29)
-Py_TPFLAGS_BASE_EXC_SUBCLASS = (1L << 30)
-Py_TPFLAGS_TYPE_SUBCLASS     = (1L << 31)
+Py_TPFLAGS_LONG_SUBCLASS     = (1 << 24)
+Py_TPFLAGS_LIST_SUBCLASS     = (1 << 25)
+Py_TPFLAGS_TUPLE_SUBCLASS    = (1 << 26)
+Py_TPFLAGS_BYTES_SUBCLASS    = (1 << 27)
+Py_TPFLAGS_UNICODE_SUBCLASS  = (1 << 28)
+Py_TPFLAGS_DICT_SUBCLASS     = (1 << 29)
+Py_TPFLAGS_BASE_EXC_SUBCLASS = (1 << 30)
+Py_TPFLAGS_TYPE_SUBCLASS     = (1 << 31)
 
 
 MAX_OUTPUT_LEN=1024
@@ -90,32 +100,39 @@ def safety_limit(val):
 def safe_range(val):
     # As per range, but don't trust the value too much: cap it to a safety
     # threshold in case the data was corrupted
-    return xrange(safety_limit(val))
-
-def write_unicode(file, text):
-    # Write a byte or unicode string to file. Unicode strings are encoded to
-    # ENCODING encoding with 'backslashreplace' error handler to avoid
-    # UnicodeEncodeError.
-    if isinstance(text, unicode):
-        text = text.encode(ENCODING, 'backslashreplace')
-    file.write(text)
-
-def os_fsencode(filename):
-    if not isinstance(filename, unicode):
-        return filename
-    encoding = sys.getfilesystemencoding()
-    if encoding == 'mbcs':
-        # mbcs doesn't support surrogateescape
-        return filename.encode(encoding)
-    encoded = []
-    for char in filename:
-        # surrogateescape error handler
-        if 0xDC80 <= ord(char) <= 0xDCFF:
-            byte = chr(ord(char) - 0xDC00)
-        else:
-            byte = char.encode(encoding)
-        encoded.append(byte)
-    return ''.join(encoded)
+    return xrange(safety_limit(int(val)))
+
+if sys.version_info[0] >= 3:
+    def write_unicode(file, text):
+        file.write(text)
+else:
+    def write_unicode(file, text):
+        # Write a byte or unicode string to file. Unicode strings are encoded to
+        # ENCODING encoding with 'backslashreplace' error handler to avoid
+        # UnicodeEncodeError.
+        if isinstance(text, unicode):
+            text = text.encode(ENCODING, 'backslashreplace')
+        file.write(text)
+
+try:
+    os_fsencode = os.fsencode
+except ImportError:
+    def os_fsencode(filename):
+        if not isinstance(filename, unicode):
+            return filename
+        encoding = sys.getfilesystemencoding()
+        if encoding == 'mbcs':
+            # mbcs doesn't support surrogateescape
+            return filename.encode(encoding)
+        encoded = []
+        for char in filename:
+            # surrogateescape error handler
+            if 0xDC80 <= ord(char) <= 0xDCFF:
+                byte = chr(ord(char) - 0xDC00)
+            else:
+                byte = char.encode(encoding)
+            encoded.append(byte)
+        return ''.join(encoded)
 
 class StringTruncated(RuntimeError):
     pass
@@ -322,8 +339,8 @@ class PyObjectPtr(object):
             # class
             return cls
 
-        #print 'tp_flags = 0x%08x' % tp_flags
-        #print 'tp_name = %r' % tp_name
+        #print('tp_flags = 0x%08x' % tp_flags)
+        #print('tp_name = %r' % tp_name)
 
         name_map = {'bool': PyBoolObjectPtr,
                     'classobj': PyClassObjectPtr,
@@ -733,14 +750,14 @@ class PyLongObjectPtr(PyObjectPtr):
         '''
         ob_size = long(self.field('ob_size'))
         if ob_size == 0:
-            return 0L
+            return 0
 
         ob_digit = self.field('ob_digit')
 
         if gdb.lookup_type('digit').sizeof == 2:
-            SHIFT = 15L
+            SHIFT = 15
         else:
-            SHIFT = 30L
+            SHIFT = 30
 
         digits = [long(ob_digit[i]) * 2**(SHIFT*i)
                   for i in safe_range(abs(ob_size))]
@@ -1595,12 +1612,12 @@ class PyList(gdb.Command):
         # py-list requires an actual PyEval_EvalFrameEx frame:
         frame = Frame.get_selected_bytecode_frame()
         if not frame:
-            print 'Unable to locate gdb frame for python bytecode interpreter'
+            print('Unable to locate gdb frame for python bytecode interpreter')
             return
 
         pyop = frame.get_pyop()
         if not pyop or pyop.is_optimized_out():
-            print 'Unable to read information on python frame'
+            print('Unable to read information on python frame')
             return
 
         filename = pyop.filename()
@@ -1656,9 +1673,9 @@ def move_in_stack(move_up):
         frame = iter_frame
 
     if move_up:
-        print 'Unable to find an older python frame'
+        print('Unable to find an older python frame')
     else:
-        print 'Unable to find a newer python frame'
+        print('Unable to find a newer python frame')
 
 class PyUp(gdb.Command):
     'Select and print the python stack frame that called this one (if any)'
@@ -1740,23 +1757,23 @@ class PyPrint(gdb.Command):
 
         frame = Frame.get_selected_python_frame()
         if not frame:
-            print 'Unable to locate python frame'
+            print('Unable to locate python frame')
             return
 
         pyop_frame = frame.get_pyop()
         if not pyop_frame:
-            print 'Unable to read information on python frame'
+            print('Unable to read information on python frame')
             return
 
         pyop_var, scope = pyop_frame.get_var_by_name(name)
 
         if pyop_var:
-            print ('%s %r = %s'
+            print('%s %r = %s'
                    % (scope,
                       name,
                       pyop_var.get_truncated_repr(MAX_OUTPUT_LEN)))
         else:
-            print '%r not found' % name
+            print('%r not found' % name)
 
 PyPrint()
 
@@ -1774,16 +1791,16 @@ class PyLocals(gdb.Command):
 
         frame = Frame.get_selected_python_frame()
         if not frame:
-            print 'Unable to locate python frame'
+            print('Unable to locate python frame')
             return
 
         pyop_frame = frame.get_pyop()
         if not pyop_frame:
-            print 'Unable to read information on python frame'
+            print('Unable to read information on python frame')
             return
 
         for pyop_name, pyop_value in pyop_frame.iter_locals():
-            print ('%s = %s'
+            print('%s = %s'
                    % (pyop_name.proxyval(set()),
                       pyop_value.get_truncated_repr(MAX_OUTPUT_LEN)))