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/*
* Copyright © Canonical Ltd.
*
* This program is free software: you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 or 3 as
* published by the Free Software Foundation.
*
* 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/>.
*/
#include "wayland_shm.h"
#include "wayland_app.h"
#include <mir/fd.h>
#include <mir/fatal.h>
#include <boost/throw_exception.hpp>
#include <fcntl.h>
#include <unistd.h>
#include <sys/mman.h>
#include <system_error>
namespace geom = mir::geometry;
namespace
{
static wl_shm_pool* make_shm_pool(wl_shm* shm, int size, void **data)
{
static auto (*open_shm_file)() -> mir::Fd = []
{
static char const* shm_dir;
open_shm_file = []{ return mir::Fd{open(shm_dir, O_TMPFILE | O_RDWR | O_EXCL, S_IRWXU)}; };
// Wayland based toolkits typically use $XDG_RUNTIME_DIR to open shm pools
// so we try that before "/dev/shm". But confined snaps can't access "/dev/shm"
// so we try "/tmp" if both of the above fail.
for (auto dir : {const_cast<const char*>(getenv("XDG_RUNTIME_DIR")), "/dev/shm", "/tmp" })
{
if (dir)
{
shm_dir = dir;
auto fd = open_shm_file();
if (fd >= 0)
return fd;
}
}
// Workaround for filesystems that don't support O_TMPFILE (E.g. phones based on 3.4 or 3.10
open_shm_file = []
{
char template_filename[] = "/dev/shm/mir-buffer-XXXXXX";
mir::Fd fd{mkostemp(template_filename, O_CLOEXEC)};
if (fd != -1)
{
if (unlink(template_filename) < 0)
{
return mir::Fd{};
}
}
return fd;
};
return open_shm_file();
};
auto fd = open_shm_file();
if (fd < 0) {
BOOST_THROW_EXCEPTION((std::system_error{errno, std::system_category(), "Failed to open shm buffer"}));
}
if (auto error = posix_fallocate(fd, 0, size))
{
BOOST_THROW_EXCEPTION((std::system_error{error, std::system_category(), "Failed to allocate shm buffer"}));
}
if ((*data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0)) == MAP_FAILED)
{
BOOST_THROW_EXCEPTION((std::system_error{errno, std::system_category(), "Failed to mmap buffer"}));
}
return wl_shm_create_pool(shm, fd, size);
}
}
struct WaylandShmPool
{
public:
WaylandShmPool(wl_shm_pool* shm_pool, void* data, size_t size)
: shm_pool{shm_pool},
data{data},
size{size}
{
}
~WaylandShmPool()
{
munmap(data, size);
wl_shm_pool_destroy(shm_pool);
}
wl_shm_pool* const shm_pool;
void* const data;
size_t const size;
};
wl_buffer_listener const WaylandShmBuffer::buffer_listener {handle_release};
WaylandShmBuffer::WaylandShmBuffer(
std::shared_ptr<WaylandShmPool> pool,
void* data,
geom::Size size,
geom::Stride stride,
wl_buffer* buffer)
: pool{pool},
data_{data},
size_{size},
stride_{stride},
buffer{buffer}
{
wl_buffer_add_listener(buffer, &buffer_listener, this);
}
WaylandShmBuffer::~WaylandShmBuffer()
{
wl_buffer_destroy(buffer);
}
auto WaylandShmBuffer::use() -> wl_buffer*
{
if (self_ptr)
{
mir::fatal_error("WaylandShmBuffer used multiple times");
}
self_ptr = shared_from_this();
return buffer;
}
void WaylandShmBuffer::handle_release(void *data, wl_buffer*)
{
auto const self = static_cast<WaylandShmBuffer*>(data);
self->self_ptr.reset();
}
WaylandShm::WaylandShm(wl_shm* shm)
: shm{shm}
{
}
auto WaylandShm::get_buffer(geom::Size size, geom::Stride stride) -> std::shared_ptr<WaylandShmBuffer>
{
// If the old buffers have a different size, clear them all
if (!buffers.empty() && (buffers[0]->size() != size || buffers[0]->stride() != stride))
{
buffers.clear();
}
std::shared_ptr<WaylandShmBuffer> free_buffer;
// We can now assume all buffers in the list are the correct size, and look for a free one
for (auto const& buffer : buffers)
{
if (!buffer->is_in_use())
{
free_buffer = buffer;
break;
}
}
// If we don't find one, we create a new buffer with a single-use pool
if (!free_buffer)
{
void* data;
size_t const data_size = size.height.as_int() * stride.as_int();
auto const pool_resource = make_shm_pool(shm, data_size, &data);
auto const pool = std::make_shared<WaylandShmPool>(pool_resource, data, data_size);
auto const buffer = wl_shm_pool_create_buffer(
pool_resource,
0,
size.width.as_int(),
size.height.as_int(),
stride.as_int(),
WL_SHM_FORMAT_ARGB8888);
free_buffer = std::make_shared<WaylandShmBuffer>(pool, data, size, stride, std::move(buffer));
buffers.push_back(free_buffer);
}
return free_buffer;
}
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