1 files changed, 85 insertions, 0 deletions
diff --git a/somebar/src/shm_buffer.cpp b/somebar/src/shm_buffer.cpp
new file mode 100644
index 0000000..59baf6f
--- /dev/null
+++ b/somebar/src/shm_buffer.cpp
@@ -0,0 +1,85 @@
+// somebar - dwl bar
+// See LICENSE file for copyright and license details.
+
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include "shm_buffer.hpp"
+#include "common.hpp"
+
+static int createAnonShm();
+constexpr int n = 2;
+
+ShmBuffer::ShmBuffer(int w, int h, wl_shm_format format)
+	: width(w)
+	, height(h)
+	, stride(w*4)
+{
+	auto oneSize = stride*size_t(h);
+	auto totalSize = oneSize * n;
+	auto fd = createAnonShm();
+	if (fd < 0) {
+		diesys("memfd_create");
+	}
+	if (ftruncate(fd, totalSize) < 0) {
+		diesys("ftruncate");
+	}
+	auto pool = wl_shm_create_pool(shm, fd, totalSize);
+	auto ptr = reinterpret_cast<uint8_t*>(mmap(nullptr, totalSize, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0));
+	if (!ptr) {
+		diesys("mmap");
+	}
+	_mapping = MemoryMapping {ptr, totalSize};
+	close(fd);
+	for (auto i=0; i<n; i++) {
+		auto offset = oneSize*i;
+		_buffers[i] = {
+			ptr+offset,
+			wl_unique_ptr<wl_buffer> { wl_shm_pool_create_buffer(pool, offset, width, height, stride, format) },
+		};
+	}
+	wl_shm_pool_destroy(pool);
+}
+
+uint8_t* ShmBuffer::data()
+{
+	return _buffers[_current].data;
+}
+
+wl_buffer* ShmBuffer::buffer()
+{
+	return _buffers[_current].buffer.get();
+}
+
+void ShmBuffer::flip()
+{
+	_current = 1-_current;
+}
+
+#if defined(__linux__)
+int createAnonShm() {
+	return memfd_create("wl_shm", MFD_CLOEXEC);
+}
+#elif defined(__FreeBSD__)
+int createAnonShm() {
+	auto fd = shm_open(SHM_ANON, O_CREAT | O_RDWR, 0600);
+	setCloexec(fd);
+	return fd;
+}
+#elif defined(__OpenBSD__)
+int createAnonShm() {
+	char name[] = "/wl_shm-XXXXXX";
+	auto fd = shm_mkstemp(name);
+	if (fd >= 0) {
+		auto res = shm_unlink(name);
+		if (res < 0) {
+			return res;
+		}
+	}
+	setCloexec(fd);
+	return fd;
+}
+#else
+#error "your system has no sane method of creating an anonymous shared memory object. no, calling shm_open in a loop is not sane."
+#endif