Add support for writing unwinders in Python.

gdb/ChangeLog:

	* Makefile.in (SUBDIR_PYTHON_OBJS): Add py-unwind.o.
	(SUBDIR_PYTHON_SRCS): Add py-unwind.c.
	(py-unwind.o): New recipe.
	* NEWS: mention Python frame unwinding.
	* data-directory/Makefile.in (PYTHON_FILE_LIST): Add
	gdb/unwinder.py and gdb/command/unwinder.py
	* python/lib/gdb/__init__.py (packages): Add frame_unwinders
	list.
	(execute_unwinders): New function.
	* python/lib/gdb/command/unwinders.py: New file.
	* python/lib/gdb/unwinder.py: New file.
	* python/py-objfile.c (objfile_object): Add frame_unwinders field.
	(objfpy_dealloc): Decrement frame_unwinders reference count.
	(objfpy_initialize): Create frame_unwinders list.
	(objfpy_get_frame_unwinders): New function.
	(objfpy_set_frame_unwinders): Ditto.
	(objfile_getset): Add frame_unwinders attribute to Objfile.
	* python/py-progspace.c (pspace_object): Add frame_unwinders field.
	(pspy_dealloc): Decrement frame_unwinders reference count.
	(pspy_initialize): Create frame_unwinders list.
	(pspy_get_frame_unwinders): New function.
	(pspy_set_frame_unwinders): Ditto.
	(pspy_getset): Add frame_unwinders attribute to gdb.Progspace.
	* python/py-unwind.c: New file.
	* python/python-internal.h (pspy_get_name_unwinders): New prototype.
	(objpy_get_frame_unwinders): New prototype.
	(gdbpy_initialize_unwind): New prototype.
	* python/python.c (gdbpy_apply_type_printers): Call
	gdbpy_initialize_unwind.

gdb/doc/ChangeLog:

	* doc/python.texi (Writing a Frame Unwinder in Python): Add
	section.

gdb/testsuite/ChangeLog:

	* gdb.python/py-unwind-maint.c: New file.
	* gdb.python/py-unwind-maint.exp: New test.
	* gdb.python/py-unwind-maint.py: New file.
	* gdb.python/py-unwind.c: New file.
	* gdb.python/py-unwind.exp: New test.
	* gdb.python/py-unwind.py: New test.

3 files changed, 329 insertions, 1 deletions

diff --git a/gdb/python/lib/gdb/__init__.py b/gdb/python/lib/gdb/__init__.py
index 92b06f2..81789e5 100644
--- a/gdb/python/lib/gdb/__init__.py
+++ b/gdb/python/lib/gdb/__init__.py
@@ -28,7 +28,7 @@ class _GdbFile (object):
     # These two are needed in Python 3
     encoding = "UTF-8"
     errors = "strict"
-    
+
     def close(self):
         # Do nothing.
         return None
@@ -71,6 +71,42 @@ type_printers = []
 xmethods = []
 # Initial frame filters.
 frame_filters = {}
+# Initial frame unwinders.
+frame_unwinders = []
+
+def execute_unwinders(pending_frame):
+    """Internal function called from GDB to execute all unwinders.
+
+    Runs each currently enabled unwinder until it finds the one that
+    can unwind given frame.
+
+    Arguments:
+        pending_frame: gdb.PendingFrame instance.
+    Returns:
+        gdb.UnwindInfo instance or None.
+    """
+    for objfile in _gdb.objfiles():
+        for unwinder in objfile.frame_unwinders:
+            if unwinder.enabled:
+                unwind_info = unwinder(pending_frame)
+                if unwind_info is not None:
+                    return unwind_info
+
+    current_progspace = _gdb.current_progspace()
+    for unwinder in current_progspace.frame_unwinders:
+        if unwinder.enabled:
+            unwind_info = unwinder(pending_frame)
+            if unwind_info is not None:
+                return unwind_info
+
+    for unwinder in frame_unwinders:
+        if unwinder.enabled:
+            unwind_info = unwinder(pending_frame)
+            if unwind_info is not None:
+                return unwind_info
+
+    return None
+
 
 # Convenience variable to GDB's python directory
 PYTHONDIR = os.path.dirname(os.path.dirname(__file__))
diff --git a/gdb/python/lib/gdb/command/unwinders.py b/gdb/python/lib/gdb/command/unwinders.py
new file mode 100644
index 0000000..8530b35
--- /dev/null
+++ b/gdb/python/lib/gdb/command/unwinders.py
@@ -0,0 +1,198 @@
+# Unwinder commands.
+# Copyright 2015 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import gdb
+import re
+
+
+def validate_regexp(exp, idstring):
+    try:
+        return re.compile(exp)
+    except SyntaxError:
+        raise SyntaxError("Invalid %s regexp: %s." % (idstring, exp))
+
+
+def parse_unwinder_command_args(arg):
+    """Internal utility to parse unwinder command argv.
+
+    Arguments:
+        arg: The arguments to the command. The format is:
+             [locus-regexp [name-regexp]]
+
+    Returns:
+        A 2-tuple of compiled regular expressions.
+
+    Raises:
+        SyntaxError: an error processing ARG
+    """
+
+    argv = gdb.string_to_argv(arg)
+    argc = len(argv)
+    if argc > 2:
+        raise SyntaxError("Too many arguments.")
+    locus_regexp = ""
+    name_regexp = ""
+    if argc >= 1:
+        locus_regexp = argv[0]
+        if argc >= 2:
+            name_regexp = argv[1]
+    return (validate_regexp(locus_regexp, "locus"),
+            validate_regexp(name_regexp, "unwinder"))
+
+
+class InfoUnwinder(gdb.Command):
+    """GDB command to list unwinders.
+
+    Usage: info unwinder [locus-regexp [name-regexp]]
+
+    LOCUS-REGEXP is a regular expression matching the location of the
+    unwinder.  If it is omitted, all registered unwinders from all
+    loci are listed.  A locus can be 'global', 'progspace' to list
+    the unwinders from the current progspace, or a regular expression
+    matching filenames of objfiles.
+
+    NAME-REGEXP is a regular expression to filter unwinder names.  If
+    this omitted for a specified locus, then all registered unwinders
+    in the locus are listed.
+    """
+
+    def __init__(self):
+        super(InfoUnwinder, self).__init__("info unwinder",
+                                            gdb.COMMAND_STACK)
+
+    def list_unwinders(self, title, unwinders, name_re):
+        """Lists the unwinders whose name matches regexp.
+
+        Arguments:
+            title: The line to print before the list.
+            unwinders: The list of the unwinders.
+            name_re: unwinder name filter.
+        """
+        if not unwinders:
+            return
+        print title
+        for unwinder in unwinders:
+            if name_re.match(unwinder.name):
+                print("  %s%s" % (unwinder.name,
+                                  "" if unwinder.enabled else " [disabled]"))
+
+    def invoke(self, arg, from_tty):
+        locus_re, name_re = parse_unwinder_command_args(arg)
+        if locus_re.match("global"):
+            self.list_unwinders("Global:", gdb.frame_unwinders,
+                                name_re)
+        if locus_re.match("progspace"):
+            cp = gdb.current_progspace()
+            self.list_unwinders("Progspace %s:" % cp.filename,
+                                cp.frame_unwinders, name_re)
+        for objfile in gdb.objfiles():
+            if locus_re.match(objfile.filename):
+                self.list_unwinders("Objfile %s:" % objfile.filename,
+                                    objfile.frame_unwinders, name_re)
+
+
+def do_enable_unwinder1(unwinders, name_re, flag):
+    """Enable/disable unwinders whose names match given regex.
+
+    Arguments:
+        unwinders: The list of unwinders.
+        name_re: Unwinder name filter.
+        flag: Enable/disable.
+
+    Returns:
+        The number of unwinders affected.
+    """
+    total = 0
+    for unwinder in unwinders:
+        if name_re.match(unwinder.name):
+            unwinder.enabled = flag
+            total += 1
+    return total
+
+
+def do_enable_unwinder(arg, flag):
+    """Enable/disable unwinder(s)."""
+    (locus_re, name_re) = parse_unwinder_command_args(arg)
+    total = 0
+    if locus_re.match("global"):
+        total += do_enable_unwinder1(gdb.frame_unwinders, name_re, flag)
+    if locus_re.match("progspace"):
+        total += do_enable_unwinder1(gdb.current_progspace().frame_unwinders,
+                                     name_re, flag)
+    for objfile in gdb.objfiles():
+        if locus_re.match(objfile.filename):
+            total += do_enable_unwinder1(objfile.frame_unwinders, name_re,
+                                         flag)
+    print("%d unwinder%s %s" % (total, "" if total == 1 else "s",
+                                "enabled" if flag else "disabled"))
+
+
+class EnableUnwinder(gdb.Command):
+    """GDB command to enable unwinders.
+
+    Usage: enable unwinder [locus-regexp [name-regexp]]
+
+    LOCUS-REGEXP is a regular expression specifying the unwinders to
+    enable.  It can 'global', 'progspace', or the name of an objfile
+    within that progspace.
+
+    NAME_REGEXP is a regular expression to filter unwinder names.  If
+    this omitted for a specified locus, then all registered unwinders
+    in the locus are affected.
+
+    """
+
+    def __init__(self):
+        super(EnableUnwinder, self).__init__("enable unwinder",
+                                             gdb.COMMAND_STACK)
+
+    def invoke(self, arg, from_tty):
+        """GDB calls this to perform the command."""
+        do_enable_unwinder(arg, True)
+
+
+class DisableUnwinder(gdb.Command):
+    """GDB command to disable the specified unwinder.
+
+    Usage: disable unwinder [locus-regexp [name-regexp]]
+
+    LOCUS-REGEXP is a regular expression specifying the unwinders to
+    disable.  It can 'global', 'progspace', or the name of an objfile
+    within that progspace.
+
+    NAME_REGEXP is a regular expression to filter unwinder names.  If
+    this omitted for a specified locus, then all registered unwinders
+    in the locus are affected.
+
+    """
+
+    def __init__(self):
+        super(DisableUnwinder, self).__init__("disable unwinder",
+                                              gdb.COMMAND_STACK)
+
+    def invoke(self, arg, from_tty):
+        """GDB calls this to perform the command."""
+        do_enable_unwinder(arg, False)
+
+
+def register_unwinder_commands():
+    """Installs the unwinder commands."""
+    InfoUnwinder()
+    EnableUnwinder()
+    DisableUnwinder()
+
+
+register_unwinder_commands()
diff --git a/gdb/python/lib/gdb/unwinder.py b/gdb/python/lib/gdb/unwinder.py
new file mode 100644
index 0000000..3554e9c
--- /dev/null
+++ b/gdb/python/lib/gdb/unwinder.py
@@ -0,0 +1,94 @@
+# Copyright (C) 2015 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+"""Unwinder class and register_unwinder function."""
+
+import gdb
+
+
+class Unwinder(object):
+    """Base class (or a template) for frame unwinders written in Python.
+
+    An unwinder has a single method __call__ and the attributes
+    described below.
+
+    Attributes:
+        name: The name of the unwinder.
+        enabled: A boolean indicating whether the unwinder is enabled.
+    """
+
+    def __init__(self, name):
+        """Constructor.
+
+        Args:
+            name: An identifying name for the unwinder.
+        """
+        self.name = name
+        self.enabled = True
+
+    def __call__(self, pending_frame):
+        """GDB calls this method to unwind a frame.
+
+        Arguments:
+            pending_frame: gdb.PendingFrame instance.
+
+        Returns:
+            gdb.UnwindInfo instance.
+        """
+        raise NotImplementedError("Unwinder __call__.")
+
+
+def register_unwinder(locus, unwinder, replace=False):
+    """Register unwinder in given locus.
+
+    The unwinder is prepended to the locus's unwinders list. Unwinder
+    name should be unique.
+
+    Arguments:
+        locus: Either an objfile, progspace, or None (in which case
+               the unwinder is registered globally).
+        unwinder: An object of a gdb.Unwinder subclass
+        replace: If True, replaces existing unwinder with the same name.
+                 Otherwise, raises exception if unwinder with the same
+                 name already exists.
+
+    Returns:
+        Nothing.
+
+    Raises:
+        RuntimeError: Unwinder name is not unique
+        TypeError: Bad locus type
+    """
+    if locus is None:
+        if gdb.parameter("verbose"):
+            gdb.write("Registering global %s unwinder ...\n" % unwinder.name)
+        locus = gdb
+    elif isinstance(locus, gdb.Objfile) or isinstance(locus, gdb.Progspace):
+        if gdb.parameter("verbose"):
+            gdb.write("Registering %s unwinder for %s ...\n" %
+                      (unwinder.name, locus.filename))
+    else:
+        raise TypeError("locus should be gdb.Objfile or gdb.Progspace or None")
+
+    i = 0
+    for needle in locus.frame_unwinders:
+        if needle.name == unwinder.name:
+            if replace:
+                del locus.frame_unwinders[i]
+            else:
+                raise RuntimeError("Unwinder %s already exists." %
+                                   unwinder.name)
+        i += 1
+    locus.frame_unwinders.insert(0, unwinder)