[Python-checkins] cpython (2.7): Fix python-gdb.py: get C types on demand

Wed Apr 20 12:24:46 EDT 2016

https://hg.python.org/cpython/rev/e4561aad29e6
changeset: 101082:e4561aad29e6
branch: 2.7
parent: 101077:ac236f1e8fd4
user: Victor Stinner <victor.stinner at gmail.com>
date: Wed Apr 20 18:23:13 2016 +0200
summary:
 Fix python-gdb.py: get C types on demand
Issue #26799: Fix python-gdb.py: don't get C types once when the Python code is
loaded, but get C types on demand. The C types can change if python-gdb.py is
loaded before the Python executable. Patch written by Thomas Ilsche.
files:
 Misc/ACKS | 1 +
 Misc/NEWS | 8 ++++++++
 Tools/gdb/libpython.py | 26 +++++++++++++++++---------
 3 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/Misc/ACKS b/Misc/ACKS
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -618,6 +618,7 @@
 Mihai Ibanescu
 Ali Ikinci
 Aaron Iles
+Thomas Ilsche
 Lars Immisch
 Bobby Impollonia
 Meador Inge
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -255,6 +255,14 @@
 
 - Issue #25136: Support Apple Xcode 7's new textual SDK stub libraries.
 
+Tools/Demos
+-----------
+
+- Issue #26799: Fix python-gdb.py: don't get C types once when the Python code
+ is loaded, but get C types on demand. The C types can change if
+ python-gdb.py is loaded before the Python executable. Patch written by Thomas
+ Ilsche.
+
 C API
 -----
 
diff --git a/Tools/gdb/libpython.py b/Tools/gdb/libpython.py
--- a/Tools/gdb/libpython.py
+++ b/Tools/gdb/libpython.py
@@ -55,11 +55,19 @@
 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*
-_type_void_ptr = gdb.lookup_type('void').pointer() # void*
+# Those need to be refreshed as types (pointer sizes) may change when
+# gdb loads different executables
 
-SIZEOF_VOID_P = _type_void_ptr.sizeof
+def _type_char_ptr():
+ return gdb.lookup_type('char').pointer() # char*
+
+
+def _type_unsigned_char_ptr():
+ return gdb.lookup_type('unsigned char').pointer() # unsigned char*
+
+
+def _sizeof_void_p():
+ return gdb.lookup_type('void').pointer().sizeof
 
 
 Py_TPFLAGS_HEAPTYPE = (1 << 9)
@@ -439,8 +447,8 @@
 
 return ( ( typeobj.field('tp_basicsize') +
 nitems * typeobj.field('tp_itemsize') +
- (SIZEOF_VOID_P - 1)
- ) & ~(SIZEOF_VOID_P - 1)
+ (_sizeof_void_p() - 1)
+ ) & ~(_sizeof_void_p() - 1)
 ).cast(_PyObject_VAR_SIZE._type_size_t)
 _PyObject_VAR_SIZE._type_size_t = None
 
@@ -464,9 +472,9 @@
 size = _PyObject_VAR_SIZE(typeobj, tsize)
 dictoffset += size
 assert dictoffset > 0
- assert dictoffset % SIZEOF_VOID_P == 0
+ assert dictoffset % _sizeof_void_p() == 0
 
- dictptr = self._gdbval.cast(_type_char_ptr) + dictoffset
+ dictptr = self._gdbval.cast(_type_char_ptr()) + dictoffset
 PyObjectPtrPtr = PyObjectPtr.get_gdb_type().pointer()
 dictptr = dictptr.cast(PyObjectPtrPtr)
 return PyObjectPtr.from_pyobject_ptr(dictptr.dereference())
@@ -1014,7 +1022,7 @@
 def __str__(self):
 field_ob_size = self.field('ob_size')
 field_ob_sval = self.field('ob_sval')
- char_ptr = field_ob_sval.address.cast(_type_unsigned_char_ptr)
+ char_ptr = field_ob_sval.address.cast(_type_unsigned_char_ptr())
 # When gdb is linked with a Python 3 interpreter, this is really
 # a latin-1 mojibake decoding of the original string...
 return ''.join([chr(char_ptr[i]) for i in safe_range(field_ob_size)])
-- 
Repository URL: https://hg.python.org/cpython
