gdb: implement 'gst-dot' and 'gst-print' commands

This adds two custom gdb commands:

'gst-dot' creates dot files that a very close to what
GST_DEBUG_BIN_TO_DOT_FILE() produces. Object properties and buffer content
(e.g. codec-data in caps) are not available.

'gst-print' produces high-level information about GStreamer objects. This
is currently limited to pads for GstElements and events for the pads. The
output can look like this:

(gdb) gst-print pad.object.parent
GstMatroskaDemux (matroskademux0) {
    SinkPad (sink, pull) {
    }
    SrcPad (video_0, push) {
      events:
        stream-start:
          stream-id: 0463ccb080d00b8689bf569a435c4ff84f9ff753545318ae2328ea0763fd0bec/001:1274058367
        caps: video/x-theora
          width: 1920
          height: 800
          pixel-aspect-ratio: 1/1
          framerate: 24/1
          streamheader: < 0x5555557c7d30 [GstBuffer], 0x5555557c7e40 [GstBuffer], 0x7fffe00141d0 [GstBuffer] >
        segment: time
          rate: 1
        tag: global
          container-format: Matroska
    }
    SrcPad (audio_0, push) {
      events:
        stream-start:
          stream-id: 0463ccb080d00b8689bf569a435c4ff84f9ff753545318ae2328ea0763fd0bec/002:1551204875
        caps: audio/mpeg
          mpegversion: 4
          framed: true
          stream-format: raw
          codec_data: 0x7fffe0014500 [GstBuffer]
          level: 2
          base-profile: lc
          profile: lc
          channels: 2
          rate: 44100
        segment: time
          rate: 1
        tag: global
          container-format: Matroska
        tag: stream
          audio-codec: MPEG-4 AAC audio
          language-code: en
    }
}

libs/gst/helpers/gst_gdb.py

@@ -1,8 +1,29 @@
+# GStreamer
+# Copyright (C) 2018 Pengutronix, Michael Olbrich <m.olbrich@pengutronix.de>
+#
+# gst_gdb.py: gdb extension for GStreamer
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Library General Public
+# License as published by the Free Software Foundation; either
+# version 2 of the License, or (at your option) any later version.
+#
+# This library 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
+# Library General Public License for more details.
+#
+# You should have received a copy of the GNU Library General Public
+# License along with this library; if not, write to the
+# Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+# Boston, MA 02110-1301, USA.
+
 import gdb
 import sys
 import re
 
-from glib_gobject_helper import g_type_to_name, g_type_name_from_instance
+from glib_gobject_helper import g_type_to_name, g_type_name_from_instance, \
+    g_type_to_typenode, g_quark_to_string
 
 if sys.version_info[0] >= 3:
     long = int
@@ -113,6 +134,829 @@ def gst_pretty_printer_lookup(val):
     return None
 
 
+def save_memory_access(fallback):
+    def _save_memory_access(func):
+        def wrapper(*args, **kwargs):
+            try:
+                return func(*args, **kwargs)
+            except gdb.MemoryError:
+                return fallback
+        return wrapper
+    return _save_memory_access
+
+
+def save_memory_access_print(message):
+    def _save_memory_access_print(func):
+        def wrapper(*args, **kwargs):
+            try:
+                func(*args, **kwargs)
+            except gdb.MemoryError:
+                _gdb_write(args[1], message)
+        return wrapper
+    return _save_memory_access_print
+
+
+def _g_type_from_instance(instance):
+    if long(instance) != 0:
+        try:
+            inst = instance.cast(gdb.lookup_type("GTypeInstance").pointer())
+            klass = inst["g_class"]
+            gtype = klass["g_type"]
+            return gtype
+        except RuntimeError:
+            pass
+    return None
+
+
+def g_inherits_type(val, typename):
+    if is_gst_type(val, "GstObject"):
+        gtype = _g_type_from_instance(val)
+        if gtype is None:
+            return False
+        typenode = g_type_to_typenode(gtype)
+    elif is_gst_type(val, "GstMiniObject"):
+        mini = val.cast(gdb.lookup_type("GstMiniObject").pointer())
+        try:
+            typenode = mini["type"].cast(gdb.lookup_type("TypeNode").pointer())
+        except gdb.MemoryError:
+            return False
+    else:
+        return False
+
+    for i in range(typenode["n_supers"]):
+        if g_type_to_name(typenode["supers"][i]) == typename:
+            return True
+    return False
+
+
+def gst_is_bin(val):
+    return g_inherits_type(val, "GstBin")
+
+
+def _g_array_iter(array, element_type):
+    if array == 0:
+        return
+    try:
+        item = array["data"].cast(element_type.pointer())
+        for i in range(int(array["len"])):
+            yield item[i]
+    except gdb.MemoryError:
+        pass
+
+
+def _g_value_get_value(val):
+    typenode = g_type_to_typenode(val["g_type"])
+    if not typenode:
+        return None
+    tname = g_quark_to_string(typenode["qname"])
+    fname = g_type_to_name(typenode["supers"][int(typenode["n_supers"])])
+    if fname in ("gchar", "guchar", "gboolean", "gint", "guint", "glong",
+                 "gulong", "gint64", "guint64", "gfloat", "gdouble",
+                 "gpointer", "GFlags"):
+        try:
+            t = gdb.lookup_type(tname).pointer()
+        except RuntimeError:
+            t = gdb.lookup_type(fname).pointer()
+    elif fname == "gchararray":
+        t = gdb.lookup_type("char").pointer().pointer()
+    elif fname == "GstBitmask":
+        t = gdb.lookup_type("guint64").pointer()
+    elif fname == "GstFlagSet":
+        t = gdb.lookup_type("guint").pointer().pointer()
+        return val["data"].cast(t)
+    elif fname == "GstFraction":
+        t = gdb.lookup_type("gint").pointer().pointer()
+        return val["data"].cast(t)
+    elif fname == "GstFractionRange":
+        t = gdb.lookup_type("GValue").pointer().pointer()
+    elif fname == "GstValueList":
+        t = gdb.lookup_type("GArray").pointer().pointer()
+    elif fname in ("GBoxed", "GObject"):
+        try:
+            t = gdb.lookup_type(tname).pointer().pointer()
+        except RuntimeError:
+            t = gdb.lookup_type(tname).pointer().pointer()
+    else:
+        return val["data"]
+
+    return val["data"].cast(t).dereference()
+
+
+def _gdb_write(indent, text):
+    gdb.write("%s%s\n" % ("  " * indent, text))
+
+
+class GdbCapsFeatures:
+    def __init__(self, val):
+        self.val = val
+
+    def size(self):
+        if long(self.val) == 0:
+            return 0
+        return int(self.val["array"]["len"])
+
+    def items(self):
+        if long(self.val) == 0:
+            return
+        for q in _g_array_iter(self.val["array"], gdb.lookup_type("GQuark")):
+            yield q
+
+    def __eq__(self, other):
+        if self.size() != other.size():
+            return False
+        a1 = list(self.items())
+        a2 = list(other.items())
+        for item in a1:
+            if item not in a2:
+                return False
+        return True
+
+    def __str__(self):
+        if long(self.val) == 0:
+            return ""
+        count = self.size()
+        if int(self.val["is_any"]) == 1 and count == 0:
+            return "(ANY)"
+        if count == 0:
+            return ""
+        s = ""
+        for f in self.items():
+            ss = g_quark_to_string(f)
+            if ss != "memory:SystemMemory" or count > 1:
+                s += ", " if s else ""
+                s += ss
+        return s
+
+
+class GdbGstCaps:
+    def __init__(self, val):
+        self.val = val.cast(gdb.lookup_type("GstCapsImpl").pointer())
+
+    def size(self):
+        return int(self.val["array"]["len"])
+
+    def items(self):
+        gdb_type = gdb.lookup_type("GstCapsArrayElement")
+        for f in _g_array_iter(self.val["array"], gdb_type):
+            yield(GdbCapsFeatures(f["features"]),
+                  GdbGstStructure(f["structure"]))
+
+    def __eq__(self, other):
+        if self.size() != other.size():
+            return False
+        a1 = list(self.items())
+        a2 = list(other.items())
+        for i in range(self.size()):
+            if a1[i] != a2[i]:
+                return False
+        return True
+
+    def dot(self):
+        if self.size() == 0:
+            return "ANY"
+        s = ""
+        for (features, structure) in self.items():
+            s += structure.name()
+            tmp = str(features)
+            if tmp:
+                s += "(" + tmp + ")"
+            s += "\\l"
+            if structure.size() > 0:
+                s += "\\l".join(structure.value_strings("  %18s: %s")) + "\\l"
+        return s
+
+    @save_memory_access_print("<inaccessible memory>")
+    def print(self, indent, prefix=""):
+        items = list(self.items())
+        if len(items) != 1:
+            _gdb_write(indent, prefix)
+            prefix = ""
+        for (features, structure) in items:
+            s = "%s %s" % (prefix, structure.name())
+            tmp = str(features)
+            if tmp:
+                s += "(" + tmp + ")"
+            _gdb_write(indent, s)
+            for val in structure.value_strings("%s: %s", False):
+                _gdb_write(indent+1, val)
+        return s
+
+
+class GdbGValue:
+    def __init__(self, val):
+        self.val = val
+
+    def fundamental_typename(self):
+        typenode = g_type_to_typenode(self.val["g_type"])
+        if not typenode:
+            return None
+        return g_type_to_name(typenode["supers"][int(typenode["n_supers"])])
+
+    def value(self):
+        return _g_value_get_value(self.val)
+
+    def __str__(self):
+        try:
+            value = self.value()
+            tname = self.fundamental_typename()
+            gvalue_type = gdb.lookup_type("GValue")
+            if tname == "GstFraction":
+                v = "%d/%d" % (value[0], value[1])
+            elif tname == "GstBitmask":
+                v = "0x%016x" % long(value)
+            elif tname == "gboolean":
+                v = "false" if int(value) == 0 else "true"
+            elif tname == "GstFlagSet":
+                v = "%x:%x" % (value[0], value[1])
+            elif tname == "GstIntRange":
+                rmin = int(value[0]["v_uint64"]) >> 32
+                rmax = int(value[0]["v_uint64"]) & 0xffffffff
+                step = int(value[1]["v_int"])
+                if step == 1:
+                    v = "[ %d, %d ]" % (rmin, rmax)
+                else:
+                    v = "[ %d, %d, %d ]" % (rmin*step, rmax*step, step)
+            elif tname == "GstFractionRange":
+                v = "[ %s, %s ]" % (GdbGValue(value[0]), GdbGValue(value[1]))
+            elif tname in ("GstValueList", "GstValueArray"):
+                if gvalue_type.fields()[1].type == value.type:
+                    gdb_type = gdb.lookup_type("GArray").pointer()
+                    value = value[0]["v_pointer"].cast(gdb_type)
+                v = "<"
+                for l in _g_array_iter(value, gvalue_type):
+                    v += " " if v == "<" else ", "
+                    v += str(GdbGValue(l))
+                v += " >"
+            else:
+                try:
+                    v = value.string()
+                except RuntimeError:
+                    # it is not a string-like type
+                    if gvalue_type.fields()[1].type == value.type:
+                        # don't print the raw GValue union
+                        v = "<unkown type: %s>" % tname
+                    else:
+                        v = str(value)
+        except gdb.MemoryError:
+            v = "<inaccessible memory at 0x%x>" % int(self.val)
+        return v
+
+    def __eq__(self, other):
+        return self.val == other.val
+
+
+class GdbGstStructure:
+    def __init__(self, val):
+        self.val = val.cast(gdb.lookup_type("GstStructureImpl").pointer())
+
+    @save_memory_access("<inaccessible memory>")
+    def name(self):
+        return g_quark_to_string(self.val["s"]["name"])
+
+    @save_memory_access(0)
+    def size(self):
+        return int(self.val["fields"]["len"])
+
+    def values(self):
+        for f in _g_array_iter(self.val["fields"],
+                               gdb.lookup_type("GstStructureField")):
+            key = g_quark_to_string(f["name"])
+            value = GdbGValue(f["value"])
+            yield(key, value)
+
+    def value(self, key):
+        for (k, value) in self.values():
+            if k == key:
+                return value
+        raise KeyError(key)
+
+    def __eq__(self, other):
+        if self.size() != other.size():
+            return False
+        a1 = list(self.values())
+        a2 = list(other.values())
+        for (key, value) in a1:
+            if (key, value) not in a2:
+                return False
+        return True
+
+    def value_strings(self, pattern, elide=True):
+        s = []
+        for (key, value) in self.values():
+            v = str(value)
+            if elide and len(v) > 25:
+                if v[0] in "[(<\"":
+                    v = v[:20] + "... " + v[-1:]
+                else:
+                    v = v[:22] + "..."
+            s.append(pattern % (key, v))
+        return s
+
+    @save_memory_access_print("<inaccessible memory>")
+    def print(self, indent, prefix=None):
+        if prefix is not None:
+            _gdb_write(indent, "%s: %s" % (prefix, self.name()))
+        else:
+            _gdb_write(indent, "%s:" % (prefix, self.name()))
+        for (key, value) in self.values():
+            _gdb_write(indent+1, "%s: %s" % (key, str(value)))
+
+
+class GdbGstEvent:
+    def __init__(self, val):
+        self.val = val.cast(gdb.lookup_type("GstEventImpl").pointer())
+
+    @save_memory_access("<inaccessible memory>")
+    def typestr(self):
+        t = self.val["event"]["type"]
+        (event_quarks, _) = gdb.lookup_symbol("event_quarks")
+        event_quarks = event_quarks.value()
+        i = 0
+        while event_quarks[i]["name"] != 0:
+            if t == event_quarks[i]["type"]:
+                return event_quarks[i]["name"].string()
+            i += 1
+        return None
+
+    def structure(self):
+        return GdbGstStructure(self.val["structure"])
+
+    @save_memory_access_print("<inaccessible memory>")
+    def print(self, indent):
+        typestr = self.typestr()
+        if typestr == "caps":
+            caps = GdbGstCaps(self.structure().value("caps").value())
+            caps.print(indent, "caps:")
+        elif typestr == "stream-start":
+            stream_id = self.structure().value("stream-id").value()
+            _gdb_write(indent, "stream-start:")
+            _gdb_write(indent + 1, "stream-id: %s" % stream_id.string())
+        elif typestr == "segment":
+            segment = self.structure().value("segment").value()
+            fmt = str(segment["format"]).split("_")[-1].lower()
+            _gdb_write(indent, "segment: %s" % fmt)
+            rate = float(segment["rate"])
+            applied_rate = float(segment["applied_rate"])
+            if applied_rate != 1.0:
+                applied = "(applied rate: %g)" % applied_rate
+            else:
+                applied = ""
+            _gdb_write(indent+1, "rate: %g%s" % (rate, applied))
+        elif typestr == "tag":
+            struct = self.structure()
+            # skip 'GstTagList-'
+            name = struct.name()[11:]
+            t = gdb.lookup_type("GstTagListImpl").pointer()
+            s = struct.value("taglist").value().cast(t)["structure"]
+            structure = GdbGstStructure(s)
+            _gdb_write(indent, "tag: %s" % name)
+            for (key, value) in structure.values():
+                _gdb_write(indent+1, "%s: %s" % (key, str(value)))
+        else:
+            self.structure().print(indent, typestr)
+
+
+class GdbGstObject:
+    def __init__(self, klass, val):
+        self.val = val.cast(klass)
+
+    @save_memory_access("<inaccessible memory>")
+    def name(self):
+        obj = self.val.cast(gdb.lookup_type("GstObject").pointer())
+        return obj["name"].string()
+
+    def dot_name(self):
+        ptr = self.val.cast(gdb.lookup_type("void").pointer())
+        return re.sub('[^a-zA-Z0-9<>]', '_', "%s_%s" % (self.name(), str(ptr)))
+
+    def parent(self):
+        obj = self.val.cast(gdb.lookup_type("GstObject").pointer())
+        return obj["parent"]
+
+    def parent_element(self):
+        p = self.parent()
+        if p != 0 and g_inherits_type(p, "GstElement"):
+            element = p.cast(gdb.lookup_type("GstElement").pointer())
+            return GdbGstElement(element)
+        return None
+
+
+class GdbGstPad(GdbGstObject):
+    def __init__(self, val):
+        gdb_type = gdb.lookup_type("GstPad").pointer()
+        super(GdbGstPad, self).__init__(gdb_type, val)
+
+    def __eq__(self, other):
+        return self.val == other.val
+
+    def is_linked(self):
+        return long(self.val["peer"]) != 0
+
+    def peer(self):
+        return GdbGstPad(self.val["peer"])
+
+    def direction(self):
+        return str(self.val["direction"])
+
+    def events(self):
+        if long(self.val["priv"]) == 0:
+            return
+        array = self.val["priv"]["events"]
+        for ev in _g_array_iter(array, gdb.lookup_type("PadEvent")):
+            yield GdbGstEvent(ev["event"])
+
+    def caps(self):
+        for ev in self.events():
+            if ev.typestr() != "caps":
+                continue
+            return GdbGstCaps(ev.structure().value("caps").value())
+        return None
+
+    def template_caps(self):
+        tmp = self.val["padtemplate"]
+        return GdbGstCaps(tmp["caps"]) if int(tmp) != 0 else None
+
+    def mode(self):
+        m = str(self.val["mode"]).split("_")[-1].lower()
+        if m in ("push", "pull"):
+            return m
+        return None
+
+    def pad_type(self):
+        s = str(self.val["direction"]).split("_")[-1].capitalize()
+        if g_inherits_type(self.val, "GstGhostPad"):
+            s += "Ghost"
+        return s + "Pad"
+
+    @save_memory_access_print("Pad(<inaccessible memory>)")
+    def print(self, indent):
+        m = ", " + self.mode() if self.mode() else ""
+        _gdb_write(indent, "%s(%s%s) {" % (self.pad_type(), self.name(), m))
+        first = True
+        for ev in self.events():
+            if first:
+                _gdb_write(indent+1, "events:")
+                first = False
+            ev.print(indent+2)
+        _gdb_write(indent, "}")
+
+    def _dot(self, color, pname, indent):
+        spc = "  " * indent
+        activation_mode = "-><"
+        style = "filled,solid"
+        template = self.val["padtemplate"]
+        if template != 0:
+            presence = template["presence"]
+            if str(presence) == "GST_PAD_SOMETIMES":
+                style = "filled,dotted"
+            if str(presence) == "GST_PAD_REQUEST":
+                style = "filled,dashed"
+        task_mode = ""
+        task = self.val["task"]
+        if long(task) != 0:
+            task_state = int(task["state"])
+            if task_state == 0:  # started
+                task_mode = "[T]"
+            if task_state == 2:  # paused
+                task_mode = "[t]"
+        f = int(self.val["object"]["flags"])
+        flags = "B" if f & 16 else "b"  # GST_PAD_FLAG_BLOCKED
+        flags += "F" if f & 32 else "f"  # GST_PAD_FLAG_FLUSHING
+        flags += "B" if f & 16 else "b"  # GST_PAD_FLAG_BLOCKING
+
+        s = "%s  %s_%s [color=black, fillcolor=\"%s\", " \
+            "label=\"%s%s\\n[%c][%s]%s\", height=\"0.2\", style=\"%s\"];\n" % \
+            (spc, pname, self.dot_name(), color, self.name(), "",
+             activation_mode[int(self.val["mode"])], flags, task_mode, style)
+        return s
+
+    def dot(self, indent):
+        spc = "  " * indent
+        direction = self.direction()
+        element = self.parent_element()
+        ename = element.dot_name() if element else ""
+        s = ""
+        if g_inherits_type(self.val, "GstGhostPad"):
+            if direction == "GST_PAD_SRC":
+                color = "#ffdddd"
+            elif direction == "GST_PAD_SINK":
+                color = "#ddddff"
+            else:
+                color = "#ffffff"
+
+            t = gdb.lookup_type("GstProxyPad").pointer()
+            other = GdbGstPad(self.val.cast(t)["priv"]["internal"])
+            if other:
+                s += other._dot(color, "", indent)
+                pname = self.dot_name()
+                other_element = other.parent_element()
+                other_ename = other_element.dot_name() if other_element else ""
+                other_pname = other.dot_name()
+                if direction == "GST_PAD_SRC":
+                    s += "%s%s_%s -> %s_%s [style=dashed, minlen=0]\n" % \
+                       (spc, other_ename, other_pname, ename, pname)
+                else:
+                    s += "%s%s_%s -> %s_%s [style=dashed, minlen=0]\n" % \
+                       (spc, ename, pname, other_ename, other_pname)
+        else:
+            if direction == "GST_PAD_SRC":
+                color = "#ffaaaa"
+            elif direction == "GST_PAD_SINK":
+                color = "#aaaaff"
+            else:
+                color = "#cccccc"
+
+        s += self._dot(color, ename, indent)
+        return s
+
+    def link_dot(self, indent, element):
+        spc = "  " * indent
+
+        peer = self.peer()
+        peer_element = peer.parent_element()
+
+        caps = self.caps()
+        if not caps:
+            caps = self.template_caps()
+        peer_caps = peer.caps()
+        if not peer_caps:
+            peer_caps = peer.template_caps()
+
+        pname = self.dot_name()
+        ename = element.dot_name() if element else ""
+        peer_pname = peer.dot_name()
+        peer_ename = peer_element.dot_name() if peer_element else ""
+
+        if caps and peer_caps and caps == peer_caps:
+            s = "%s%s_%s -> %s_%s [label=\"%s\"]\n" % \
+               (spc, ename, pname, peer_ename, peer_pname, caps.dot())
+        elif caps and peer_caps and caps != peer_caps:
+            s = "%s%s_%s -> %s_%s [labeldistance=\"10\", labelangle=\"0\", " \
+                % (spc, ename, pname, peer_ename, peer_pname)
+            s += "label=\"" + " "*50 + "\", "
+            if self.direction() == "GST_PAD_SRC":
+                media_src = caps.dot()
+                media_dst = peer_caps.dot()
+            else:
+                media_src = peer_caps.dot()
+                media_dst = caps.dot()
+            s += "taillabel=\"%s\", headlabel=\"%s\"]\n" % \
+                 (media_src, media_dst)
+        else:
+            s = "%s%s_%s -> %s_%s\n" % \
+                (spc, ename, pname, peer_ename, peer_pname)
+        return s
+
+
+class GdbGstElement(GdbGstObject):
+    def __init__(self, val):
+        gdb_type = gdb.lookup_type("GstElement").pointer()
+        super(GdbGstElement, self).__init__(gdb_type, val)
+        self.is_bin = gst_is_bin(self.val)
+
+    def __eq__(self, other):
+        return self.val == other.val
+
+    def children(self):
+        if not self.is_bin:
+            return
+        b = self.val.cast(gdb.lookup_type("GstBin").pointer())
+        link = b["children"]
+        while link != 0:
+            yield GdbGstElement(link["data"])
+            link = link["next"]
+
+    def has_pads(self, pad_group="pads"):
+        return self.val[pad_group] != 0
+
+    def pads(self, pad_group="pads"):
+        link = self.val[pad_group]
+        while link != 0:
+            yield GdbGstPad(link["data"])
+            link = link["next"]
+
+    def _state_dot(self):
+        icons = "~0-=>"
+        current = int(self.val["current_state"])
+        pending = int(self.val["pending_state"])
+        if pending == 0:
+            # GST_ELEMENT_FLAG_LOCKED_STATE == 16
+            locked = (int(self.val["object"]["flags"]) & 16) != 0
+            return "\\n[%c]%s" % (icons[current], "(locked)" if locked else "")
+        return "\\n[%c] -> [%c]" % (icons[current], icons[pending])
+
+    @save_memory_access_print("Element(<inaccessible memory>)")
+    def print(self, indent):
+        _gdb_write(indent, "%s(%s) {" %
+                   (g_type_name_from_instance(self.val), self.name()))
+        for p in self.pads():
+            p.print(indent+2)
+        _gdb_write(indent, "}")
+
+    def _dot(self, indent=0):
+        spc = "  " * indent
+
+        s = "%ssubgraph cluster_%s {\n" % (spc, self.dot_name())
+        s += "%s  fontname=\"Bitstream Vera Sans\";\n" % spc
+        s += "%s  fontsize=\"8\";\n" % spc
+        s += "%s  style=\"filled,rounded\";\n" % spc
+        s += "%s  color=black;\n" % spc
+        s += "%s  label=\"%s\\n%s%s%s\";\n" % \
+             (spc, g_type_name_from_instance(self.val), self.name(),
+              self._state_dot(), "")
+
+        sink_name = None
+        if self.has_pads("sinkpads"):
+            (ss, sink_name) = self._dot_pads(indent+1, "sinkpads",
+                                             self.dot_name() + "_sink")
+            s += ss
+        src_name = None
+        if self.has_pads("srcpads"):
+            (ss, src_name) = self._dot_pads(indent+1, "srcpads",
+                                            self.dot_name() + "_src")
+            s += ss
+        if sink_name and src_name:
+            name = self.dot_name()
+            s += "%s  %s_%s -> %s_%s [style=\"invis\"];\n" % \
+                 (spc, name, sink_name, name, src_name)
+
+        if gst_is_bin(self.val):
+            s += "%s  fillcolor=\"#ffffff\";\n" % spc
+            s += self.dot(indent+1)
+        else:
+            if src_name and not sink_name:
+                s += "%s  fillcolor=\"#ffaaaa\";\n" % spc
+            elif not src_name and sink_name:
+                s += "%s  fillcolor=\"#aaaaff\";\n" % spc
+            elif src_name and sink_name:
+                s += "%s  fillcolor=\"#aaffaa\";\n" % spc
+            else:
+                s += "%s  fillcolor=\"#ffffff\";\n" % spc
+        s += "%s}\n\n" % spc
+
+        for p in self.pads():
+            if not p.is_linked():
+                continue
+            if p.direction() == "GST_PAD_SRC":
+                s += p.link_dot(indent, self)
+            else:
+                pp = p.peer()
+                if not g_inherits_type(pp.val, "GstGhostPad") and \
+                   g_inherits_type(pp.val, "GstProxyPad"):
+                    s += pp.link_dot(indent, None)
+        return s
+
+    def _dot_pads(self, indent, pad_group, cluster_name):
+        spc = "  " * indent
+        s = "%ssubgraph cluster_%s {\n" % (spc, cluster_name)
+        s += "%s  label=\"\";\n" % spc
+        s += "%s  style=\"invis\";\n" % spc
+        name = None
+        for p in self.pads(pad_group):
+            s += p.dot(indent)
+            if not name:
+                name = p.dot_name()
+        s += "%s}\n\n" % spc
+        return(s, name)
+
+    def dot(self, indent):
+        s = ""
+        for child in self.children():
+            try:
+                s += child._dot(indent)
+            except gdb.MemoryError:
+                gdb.write("warning: inaccessible memory in element 0x%x\n" %
+                          long(child.val))
+        return s
+
+    def pipeline_dot(self):
+        t = g_type_name_from_instance(self.val)
+
+        s = "digraph pipeline {\n"
+        s += "  rankdir=LR;\n"
+        s += "  fontname=\"sans\";\n"
+        s += "  fontsize=\"10\";\n"
+        s += "  labelloc=t;\n"
+        s += "  nodesep=.1;\n"
+        s += "  ranksep=.2;\n"
+        s += "  label=\"<%s>\\n%s%s%s\";\n" % (t, self.name(), "", "")
+        s += "  node [style=\"filled,rounded\", shape=box, fontsize=\"9\", " \
+             "fontname=\"sans\", margin=\"0.0,0.0\"];\n"
+        s += "  edge [labelfontsize=\"6\", fontsize=\"9\", " \
+             "fontname=\"monospace\"];\n"
+        s += "  \n"
+        s += "  legend [\n"
+        s += "    pos=\"0,0!\",\n"
+        s += "    margin=\"0.05,0.05\",\n"
+        s += "    style=\"filled\",\n"
+        s += "    label=\"Legend\\lElement-States: [~] void-pending, " \
+             "[0] null, [-] ready, [=] paused, [>] playing\\l" \
+             "Pad-Activation: [-] none, [>] push, [<] pull\\l" \
+             "Pad-Flags: [b]locked, [f]lushing, [b]locking, [E]OS; " \
+             "upper-case is set\\lPad-Task: [T] has started task, " \
+             "[t] has paused task\\l\",\n"
+        s += "  ];"
+        s += "\n"
+
+        s += self.dot(1)
+
+        s += "}\n"
+
+        return s
+
+
+class GstDot(gdb.Command):
+    """\
+Create a pipeline dot file as close as possible to the output of
+GST_DEBUG_BIN_TO_DOT_FILE. This command will find the top-level parent
+for the given gstreamer object and create the dot for that element.
+
+Usage: gst-dot <gst-object> <file-name>"""
+    def __init__(self):
+        super(GstDot, self).__init__("gst-dot", gdb.COMMAND_DATA)
+
+    def invoke(self, arg, from_tty):
+        self.dont_repeat()
+        args = gdb.string_to_argv(arg)
+        if len(args) != 2:
+            raise Exception("Usage: gst-dot <gst-object> <file>")
+
+        value = gdb.parse_and_eval(args[0])
+        if not value:
+            raise Exception("'%s' is not a valid object" % args[0])
+
+        if value.type.code != gdb.TYPE_CODE_PTR:
+            value = value.address
+
+        if not is_gst_type(value, "GstObject"):
+            raise Exception("'%s' is not a GstObject" % args[0])
+
+        value = value.cast(gdb.lookup_type("GstObject").pointer())
+        try:
+            while value["parent"] != 0:
+                tmp = value["parent"]
+                # sanity checks to handle memory corruption
+                if g_inherits_type(value, "GstElement") and \
+                   GdbGstElement(value) not in GdbGstElement(tmp).children():
+                    break
+                if g_inherits_type(value, "GstPad") and \
+                   GdbGstPad(value) not in GdbGstElement(tmp).pads():
+                    break
+                value = tmp
+        except gdb.MemoryError:
+            pass
+
+        if not g_inherits_type(value, "GstElement"):
+            raise Exception("Toplevel parent is not a GstElement")
+        value = value.cast(gdb.lookup_type("GstElement").pointer())
+
+        dot = GdbGstElement(value).pipeline_dot()
+        file = open(args[1], "w")
+        file.write(dot)
+        file.close()
+
+    def complete(self, text, word):
+        cmd = gdb.string_to_argv(text)
+        if len(cmd) == 0 or(len(cmd) == 1 and len(word) > 0):
+            return gdb.COMPLETE_SYMBOL
+        return gdb.COMPLETE_FILENAME
+
+
+class GstPrint(gdb.Command):
+    """\
+Print high-level information for GStreamer objects
+
+Usage gst-print <gstreamer-object>"""
+    def __init__(self):
+        super(GstPrint, self).__init__("gst-print", gdb.COMMAND_DATA,
+                                       gdb.COMPLETE_SYMBOL)
+
+    def invoke(self, arg, from_tty):
+        value = gdb.parse_and_eval(arg)
+        if not value:
+            raise Exception("'%s' is not a valid object" % args[0])
+
+        if value.type.code != gdb.TYPE_CODE_PTR:
+            value = value.address
+
+        if g_inherits_type(value, "GstElement"):
+            obj = GdbGstElement(value)
+        elif g_inherits_type(value, "GstPad"):
+            obj = GdbGstPad(value)
+        elif g_inherits_type(value, "GstCaps"):
+            obj = GdbGstCaps(value)
+        elif g_inherits_type(value, "GstEvent"):
+            obj = GdbGstCaps(value)
+        else:
+            raise Exception("'%s' has an unkown type" % arg)
+
+        obj.print(0)
+
+
+GstDot()
+GstPrint()
+
+
 def register(obj):
     if obj is None:
         obj = gdb