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new "Electric Fence" element, that converts each buffer into an allocated region surrounded by two unmapped pages.

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Original commit message from CVS:
new "Electric Fence" element, that converts each buffer into an allocated
region surrounded by two unmapped pages.
This commit is contained in:
David Schleef 2003-06-22 03:58:04 +00:00
parent d1b4db094c
commit 3d3cec6e7e
3 changed files with 494 additions and 0 deletions
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11
gst/debug/Makefile.am Normal file
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plugindir= $(libdir)/gstreamer-@GST_MAJORMINOR@
plugin_LTLIBRARIES = libgstefence.la
noinst_HEADERS = efence.h
libgstefence_la_SOURCES = efence.c
libgstefence_la_CFLAGS = $(GST_CFLAGS)
libgstefence_la_LDFLAGS = $(GST_LIBS)

434
gst/debug/efence.c Normal file
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/*
* GStreamer
* Copyright (C) 1999-2001 Erik Walthinsen <omega@cse.ogi.edu>
* Copyright (C) 2002 David A. Schleef <ds@schleef.org>
*
* 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., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include <gst/gst.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#include "efence.h"
static GstElementDetails plugin_details = {
"Electric Fence",
"Testing/EFence",
"LGPL",
"This element converts a stream of normal GStreamer buffers into a "
"stream of buffers that are allocated in such a way that out-of-bounds "
"access to data in the buffer is more likely to cause segmentation "
"faults. This allocation method is very similar to the debugging tool "
"\"Electric Fence\".",
VERSION,
"David A. Schleef <ds@schleef.org>",
"(C) 2002, 2003"
};
/* Filter signals and args */
enum {
/* FILL ME */
LAST_SIGNAL
};
enum {
ARG_0,
ARG_FENCE_TOP
};
GST_PAD_TEMPLATE_FACTORY (gst_efence_sink_factory,
"sink",
GST_PAD_SINK,
GST_PAD_ALWAYS,
NULL /* no caps */
);
GST_PAD_TEMPLATE_FACTORY (gst_efence_src_factory,
"src",
GST_PAD_SRC,
GST_PAD_ALWAYS,
NULL /* no caps */
);
static void gst_efence_class_init (GstEFenceClass *klass);
static void gst_efence_init (GstEFence *filter);
static void gst_efence_set_property(GObject *object, guint prop_id,
const GValue *value,
GParamSpec *pspec);
static void gst_efence_get_property(GObject *object, guint prop_id,
GValue *value,
GParamSpec *pspec);
static void gst_efence_chain (GstPad *pad, GstBuffer *buf);
static GstElementClass *parent_class = NULL;
typedef struct _GstFencedBuffer GstFencedBuffer;
struct _GstFencedBuffer {
GstBuffer buffer;
void *region;
unsigned int length;
};
void gst_fenced_buffer_default_free (GstBuffer *buffer);
GstBuffer* gst_fenced_buffer_default_copy (GstBuffer *buffer);
void *gst_fenced_buffer_alloc(GstBuffer *buffer, unsigned int length,
gboolean fence_top);
GstBuffer *gst_fenced_buffer_new(void);
static GstPadLinkReturn
gst_efence_link (GstPad *pad, GstCaps *caps)
{
GstEFence *filter;
GstPad *otherpad;
filter = GST_EFENCE (gst_pad_get_parent (pad));
g_return_val_if_fail (filter != NULL, GST_PAD_LINK_REFUSED);
g_return_val_if_fail (GST_IS_EFENCE (filter),
GST_PAD_LINK_REFUSED);
otherpad = (pad == filter->srcpad ? filter->sinkpad : filter->srcpad);
if (GST_CAPS_IS_FIXED (caps))
{
/* caps are not fixed, so try to link on the other side and see if
* that works */
if (!gst_pad_try_set_caps (otherpad, caps))
return GST_PAD_LINK_REFUSED;
/* caps on other side were accepted, so we're ok */
return GST_PAD_LINK_OK;
}
/* not enough information yet, delay negotation */
return GST_PAD_LINK_DELAYED;
}
GType
gst_gst_efence_get_type (void)
{
static GType plugin_type = 0;
if (!plugin_type)
{
static const GTypeInfo plugin_info =
{
sizeof (GstEFenceClass),
NULL,
NULL,
(GClassInitFunc) gst_efence_class_init,
NULL,
NULL,
sizeof (GstEFence),
0,
(GInstanceInitFunc) gst_efence_init,
};
plugin_type = g_type_register_static (GST_TYPE_ELEMENT,
"GstEFence",
&plugin_info, 0);
}
return plugin_type;
}
/* initialize the plugin's class */
static void
gst_efence_class_init (GstEFenceClass *klass)
{
GObjectClass *gobject_class;
GstElementClass *gstelement_class;
gobject_class = (GObjectClass*) klass;
gstelement_class = (GstElementClass*) klass;
parent_class = g_type_class_ref (GST_TYPE_ELEMENT);
g_object_class_install_property (gobject_class, ARG_FENCE_TOP,
g_param_spec_boolean ("fence_top", "Fence Top", "Align buffers with top of fenced region",
TRUE, G_PARAM_READWRITE));
gobject_class->set_property = gst_efence_set_property;
gobject_class->get_property = gst_efence_get_property;
}
/* initialize the new element
* instantiate pads and add them to element
* set functions
* initialize structure
*/
static void
gst_efence_init (GstEFence *filter)
{
filter->sinkpad = gst_pad_new_from_template (gst_efence_sink_factory (),
"sink");
gst_pad_set_link_function (filter->sinkpad, gst_efence_link);
filter->srcpad = gst_pad_new_from_template (gst_efence_src_factory (),
"src");
gst_pad_set_link_function (filter->srcpad, gst_efence_link);
gst_element_add_pad (GST_ELEMENT (filter), filter->sinkpad);
gst_element_add_pad (GST_ELEMENT (filter), filter->srcpad);
gst_pad_set_chain_function (filter->sinkpad, gst_efence_chain);
filter->fence_top = TRUE;
}
/* chain function
* this function does the actual processing
*/
static void
gst_efence_chain (GstPad *pad, GstBuffer *buffer)
{
GstEFence *efence;
GstBuffer *copy;
void *ptr;
GST_DEBUG(0, "gst_efence_chain");
g_return_if_fail (GST_IS_PAD (pad));
g_return_if_fail (buffer != NULL);
efence = GST_EFENCE (GST_OBJECT_PARENT (pad));
g_return_if_fail (GST_IS_EFENCE (efence));
copy = gst_fenced_buffer_new();
ptr = gst_fenced_buffer_alloc(copy, GST_BUFFER_SIZE(buffer),
efence->fence_top);
memcpy(ptr, GST_BUFFER_DATA(buffer), GST_BUFFER_SIZE(buffer));
GST_BUFFER_DATA (copy) = ptr;
GST_BUFFER_SIZE (copy) = GST_BUFFER_SIZE (buffer);
GST_BUFFER_MAXSIZE (copy) = GST_BUFFER_SIZE (buffer);
GST_BUFFER_TIMESTAMP (copy) = GST_BUFFER_TIMESTAMP (buffer);
GST_BUFFER_DURATION (copy) = GST_BUFFER_DURATION (buffer);
GST_BUFFER_OFFSET (copy) = GST_BUFFER_OFFSET (buffer);
GST_BUFFER_BUFFERPOOL (copy) = NULL;
GST_BUFFER_POOL_PRIVATE (copy) = NULL;
gst_buffer_unref(buffer);
gst_pad_push (efence->srcpad, copy);
}
static void
gst_efence_set_property (GObject *object, guint prop_id,
const GValue *value, GParamSpec *pspec)
{
GstEFence *filter;
g_return_if_fail (GST_IS_EFENCE (object));
filter = GST_EFENCE (object);
switch (prop_id)
{
case ARG_FENCE_TOP:
filter->fence_top = g_value_get_boolean (value);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
gst_efence_get_property (GObject *object, guint prop_id,
GValue *value, GParamSpec *pspec)
{
GstEFence *filter;
g_return_if_fail (GST_IS_EFENCE (object));
filter = GST_EFENCE (object);
switch (prop_id) {
case ARG_FENCE_TOP:
g_value_set_boolean (value, filter->fence_top);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
/* entry point to initialize the plug-in
* initialize the plug-in itself
* register the element factories and pad templates
* register the features
*/
static gboolean
plugin_init (GModule *module, GstPlugin *plugin)
{
GstElementFactory *factory;
factory = gst_element_factory_new ("efence", GST_TYPE_EFENCE,
&plugin_details);
g_return_val_if_fail (factory != NULL, FALSE);
gst_element_factory_add_pad_template (factory,
gst_efence_src_factory ());
gst_element_factory_add_pad_template (factory,
gst_efence_sink_factory ());
gst_plugin_add_feature (plugin, GST_PLUGIN_FEATURE (factory));
/* plugin initialisation succeeded */
return TRUE;
}
/* this is the structure that gst-register looks for
* so keep the name plugin_desc, or you cannot get your plug-in registered */
GstPluginDesc plugin_desc = {
GST_VERSION_MAJOR,
GST_VERSION_MINOR,
"efence",
plugin_init
};
GstBuffer *gst_fenced_buffer_new(void)
{
GstBuffer *newbuf;
newbuf = (GstBuffer *) g_new0(GstFencedBuffer,1);
gst_data_init (GST_DATA (newbuf), _gst_buffer_type, 0,
(GstDataFreeFunction) gst_fenced_buffer_default_free,
(GstDataCopyFunction) gst_fenced_buffer_default_copy);
GST_BUFFER_DATA (newbuf) = NULL;
GST_BUFFER_SIZE (newbuf) = 0;
GST_BUFFER_MAXSIZE (newbuf) = GST_BUFFER_MAXSIZE_NONE;
GST_BUFFER_TIMESTAMP (newbuf) = GST_CLOCK_TIME_NONE;
GST_BUFFER_DURATION (newbuf) = GST_CLOCK_TIME_NONE;
GST_BUFFER_OFFSET (newbuf) = GST_BUFFER_OFFSET_NONE;
GST_BUFFER_BUFFERPOOL (newbuf) = NULL;
GST_BUFFER_POOL_PRIVATE (newbuf) = NULL;
GST_DEBUG(0, "new buffer=%p", newbuf);
return newbuf;
}
void gst_fenced_buffer_default_free (GstBuffer *buffer)
{
GstFencedBuffer *fenced_buffer;
GST_DEBUG(0, "free buffer=%p", buffer);
g_return_if_fail (buffer != NULL);
fenced_buffer = (GstFencedBuffer *) buffer;
/* free our data */
if (!GST_BUFFER_FLAG_IS_SET (buffer, GST_BUFFER_DONTFREE) &&
GST_BUFFER_DATA (buffer)) {
GST_DEBUG(0, "free region %p %d", fenced_buffer->region,
fenced_buffer->length);
munmap(fenced_buffer->region, fenced_buffer->length);
}else{
GST_DEBUG(0, "not freeing region %p %d %p", fenced_buffer->region,
GST_BUFFER_FLAGS(buffer), GST_BUFFER_DATA(buffer));
}
/* set to safe values */
GST_BUFFER_DATA (buffer) = NULL;
GST_BUFFER_SIZE (buffer) = 0;
g_free (buffer);
}
GstBuffer* gst_fenced_buffer_default_copy (GstBuffer *buffer)
{
GstBuffer *copy;
void *ptr;
g_return_val_if_fail (buffer != NULL, NULL);
/* create a fresh new buffer */
copy = (GstBuffer *) g_new0(GstFencedBuffer,1);
gst_data_init (GST_DATA (copy), _gst_buffer_type, 0,
(GstDataFreeFunction) gst_fenced_buffer_default_free,
(GstDataCopyFunction) gst_fenced_buffer_default_copy);
/* we simply copy everything from our parent */
ptr = gst_fenced_buffer_alloc(copy, GST_BUFFER_SIZE(buffer), TRUE);
memcpy(ptr, GST_BUFFER_DATA(buffer), GST_BUFFER_SIZE(buffer));
GST_BUFFER_SIZE (copy) = GST_BUFFER_SIZE (buffer);
GST_BUFFER_MAXSIZE (copy) = GST_BUFFER_SIZE (buffer);
GST_BUFFER_TIMESTAMP (copy) = GST_BUFFER_TIMESTAMP (buffer);
GST_BUFFER_DURATION (copy) = GST_BUFFER_DURATION (buffer);
GST_BUFFER_OFFSET (copy) = GST_BUFFER_OFFSET (buffer);
GST_BUFFER_BUFFERPOOL (copy) = NULL;
GST_BUFFER_POOL_PRIVATE (copy) = NULL;
return copy;
}
void *gst_fenced_buffer_alloc(GstBuffer *buffer, unsigned int length,
gboolean fence_top)
{
int alloc_size;
void *region;
GstFencedBuffer *fenced_buffer = (GstFencedBuffer *) buffer;
int page_size;
GST_DEBUG(0, "buffer=%p length=%d fence_top=%d", buffer, length, fence_top);
if(length==0)return NULL;
#ifdef _SC_PAGESIZE
page_size = sysconf(_SC_PAGESIZE);
#else
page_size = getpagesize();
#endif
alloc_size = ((length - 1) & ~(page_size - 1)) + page_size;
alloc_size += 2*page_size;
region = mmap(NULL, alloc_size, PROT_READ|PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if(region == MAP_FAILED){
g_warning("mmap failed");
return NULL;
}
munmap(region, page_size);
munmap(region + alloc_size - page_size, page_size);
fenced_buffer->region = region;
fenced_buffer->length = alloc_size;
GST_DEBUG(0, "new region %p %d", fenced_buffer->region,
fenced_buffer->length);
if(fence_top){
int offset;
/* Align to top of region, but force alignment to 4 bytes */
offset = alloc_size - page_size - length;
offset &= ~0x3;
return region + offset;
}else{
return region + page_size;
}
}

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/*
* efence.h
*/
#ifndef __GST_EFENCE_H__
#define __GST_EFENCE_H__
#include <gst/gst.h>
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
/* #define's don't like whitespacey bits */
#define GST_TYPE_EFENCE \
(gst_gst_efence_get_type())
#define GST_EFENCE(obj) \
(G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_EFENCE,GstEFence))
#define GST_EFENCE_CLASS(klass) \
(G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_EFENCE,GstEFence))
#define GST_IS_EFENCE(obj) \
(G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_EFENCE))
#define GST_IS_EFENCE_CLASS(obj) \
(G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_EFENCE))
typedef struct _GstEFence GstEFence;
typedef struct _GstEFenceClass GstEFenceClass;
struct _GstEFence
{
GstElement element;
GstPad *sinkpad, *srcpad;
gboolean fence_top;
};
struct _GstEFenceClass
{
GstElementClass parent_class;
};
GType gst_gst_efence_get_type (void);
#ifdef __cplusplus
}
#endif /* __cplusplus */
#endif /* __GST_EFENCE_H__ */