ladybird/Kernel/API/Graphics.h
Liav A 977aa81310 Kernel+Userland: Add ioctl to set process ownership of DisplayConnector
Now that the infrastructure of the Graphics subsystem is quite stable,
it is time to try to fix a long-standing problem, which is the lack of
locking on display connector devices. Reading and writing from multiple
processes to a framebuffer controlled by the display connector is not a
huge problem - it could be solved with POSIX locking.

The real problem is some program that will try to do ioctl operations on
a display connector without the WindowServer being aware of that which
can lead to very bad situations, for example - assuming a framebuffer is
encoded at a known resolution and certain display timings, but another
process changed the ModeSetting of the display connector, leading to
inconsistency on the properties of the current ModeSetting.

To solve this, there's a new "master" ioctl to take "ownership" and
another one to release that ownership of a display connector device. To
ensure we will not hold a Process object forever just because it has an
ownership over a display connector, we hold it with a weak reference,
and if the process is gone, someone else can take an ownership.
2022-07-23 10:42:08 +01:00

118 lines
3.9 KiB
C

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Platform.h>
#include <AK/ScopeGuard.h>
#include <AK/String.h>
#include <fcntl.h>
#include <stddef.h>
#include <stdio.h>
#include <sys/cdefs.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/sysmacros.h>
#include <unistd.h>
__BEGIN_DECLS
ALWAYS_INLINE int graphics_connector_get_properties(int fd, GraphicsConnectorProperties* info)
{
return ioctl(fd, GRAPHICS_IOCTL_GET_PROPERTIES, info);
}
ALWAYS_INLINE int graphics_connector_get_head_edid(int fd, GraphicsHeadEDID* info)
{
// FIXME: Optimize this function to get a minor number instead of a file descriptor.
struct stat display_connector_stat;
if (auto rc = fstat(fd, &display_connector_stat); rc < 0) {
return rc;
}
auto minor_number = minor(display_connector_stat.st_rdev);
auto edid_fd = open(String::formatted("/sys/devices/graphics/connectors/{}/edid", minor_number).characters(), O_RDONLY);
if (edid_fd < 0) {
return edid_fd;
}
ScopeGuard close_on_return([&]() {
close(edid_fd);
});
if (auto rc = read(edid_fd, info->bytes, info->bytes_size); rc < 0) {
return rc;
}
return 0;
}
ALWAYS_INLINE int graphics_connector_set_responsible(int fd)
{
return ioctl(fd, GRAPHICS_IOCTL_SET_RESPONSIBLE, nullptr);
}
ALWAYS_INLINE int graphics_connector_unset_responsible(int fd)
{
return ioctl(fd, GRAPHICS_IOCTL_UNSET_RESPONSIBLE, nullptr);
}
ALWAYS_INLINE int fb_get_head_vertical_offset_buffer(int fd, GraphicsHeadVerticalOffset* vertical_offset)
{
return ioctl(fd, GRAPHICS_IOCTL_GET_HEAD_VERTICAL_OFFSET_BUFFER, vertical_offset);
}
ALWAYS_INLINE int fb_set_head_vertical_offset_buffer(int fd, GraphicsHeadVerticalOffset* vertical_offset)
{
return ioctl(fd, GRAPHICS_IOCTL_SET_HEAD_VERTICAL_OFFSET_BUFFER, vertical_offset);
}
ALWAYS_INLINE int graphics_connector_set_head_mode_setting(int fd, GraphicsHeadModeSetting* mode_setting)
{
return ioctl(fd, GRAPHICS_IOCTL_SET_HEAD_MODE_SETTING, mode_setting);
}
ALWAYS_INLINE int graphics_connector_set_safe_head_mode_setting(int fd)
{
return ioctl(fd, GRAPHICS_IOCTL_SET_SAFE_HEAD_MODE_SETTING, nullptr);
}
ALWAYS_INLINE int graphics_connector_get_head_mode_setting(int fd, GraphicsHeadModeSetting* mode_setting)
{
GraphicsHeadModeSetting head_mode_setting;
if (auto rc = ioctl(fd, GRAPHICS_IOCTL_GET_HEAD_MODE_SETTING, &head_mode_setting); rc < 0)
return rc;
mode_setting->horizontal_stride = head_mode_setting.horizontal_stride;
mode_setting->pixel_clock_in_khz = head_mode_setting.pixel_clock_in_khz;
mode_setting->horizontal_active = head_mode_setting.horizontal_active;
mode_setting->horizontal_front_porch_pixels = head_mode_setting.horizontal_front_porch_pixels;
mode_setting->horizontal_sync_time_pixels = head_mode_setting.horizontal_sync_time_pixels;
mode_setting->horizontal_blank_pixels = head_mode_setting.horizontal_blank_pixels;
mode_setting->vertical_active = head_mode_setting.vertical_active;
mode_setting->vertical_front_porch_lines = head_mode_setting.vertical_front_porch_lines;
mode_setting->vertical_sync_time_lines = head_mode_setting.vertical_sync_time_lines;
mode_setting->vertical_blank_lines = head_mode_setting.vertical_blank_lines;
mode_setting->horizontal_offset = head_mode_setting.horizontal_offset;
mode_setting->vertical_offset = head_mode_setting.vertical_offset;
return 0;
}
ALWAYS_INLINE int fb_flush_buffers(int fd, int index, FBRect const* rects, unsigned count)
{
FBFlushRects fb_flush_rects;
fb_flush_rects.buffer_index = index;
fb_flush_rects.count = count;
fb_flush_rects.rects = rects;
return ioctl(fd, GRAPHICS_IOCTL_FLUSH_HEAD_BUFFERS, &fb_flush_rects);
}
ALWAYS_INLINE int fb_flush_head(int fd)
{
return ioctl(fd, GRAPHICS_IOCTL_FLUSH_HEAD, nullptr);
}
__END_DECLS