1 files changed, 145 insertions, 0 deletions
diff --git a/pool-buffer.c b/pool-buffer.c
new file mode 100644
index 0000000..aca95a1
--- /dev/null
+++ b/pool-buffer.c
@@ -0,0 +1,145 @@
+#define _POSIX_C_SOURCE 200809L
+#include <assert.h>
+#include <cairo.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <pango/pangocairo.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <time.h>
+#include <unistd.h>
+#include <wayland-client.h>
+#include "pool-buffer.h"
+
+static void randname(char *buf) {
+	struct timespec ts;
+	clock_gettime(CLOCK_REALTIME, &ts);
+	long r = ts.tv_nsec;
+	for (int i = 0; i < 6; ++i) {
+		buf[i] = 'A'+(r&15)+(r&16)*2;
+		r >>= 5;
+	}
+}
+
+static int anonymous_shm_open(void) {
+	char name[] = "/wmenu-XXXXXX";
+	int retries = 100;
+
+	do {
+		randname(name + strlen(name) - 6);
+
+		--retries;
+		// shm_open guarantees that O_CLOEXEC is set
+		int fd = shm_open(name, O_RDWR | O_CREAT | O_EXCL, 0600);
+		if (fd >= 0) {
+			shm_unlink(name);
+			return fd;
+		}
+	} while (retries > 0 && errno == EEXIST);
+
+	return -1;
+}
+
+static int create_shm_file(off_t size) {
+	int fd = anonymous_shm_open();
+	if (fd < 0) {
+		return fd;
+	}
+
+	if (ftruncate(fd, size) < 0) {
+		close(fd);
+		return -1;
+	}
+
+	return fd;
+}
+
+static void buffer_release(void *data, struct wl_buffer *wl_buffer) {
+	struct pool_buffer *buffer = data;
+	buffer->busy = false;
+}
+
+static const struct wl_buffer_listener buffer_listener = {
+	.release = buffer_release
+};
+
+static struct pool_buffer *create_buffer(struct wl_shm *shm,
+		struct pool_buffer *buf, int32_t width, int32_t height,
+		int32_t scale, uint32_t format) {
+	uint32_t stride = width * scale * 4;
+	size_t size = stride * height * scale;
+
+	int fd = create_shm_file(size);
+	assert(fd != -1);
+	void *data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+	struct wl_shm_pool *pool = wl_shm_create_pool(shm, fd, size);
+	buf->buffer = wl_shm_pool_create_buffer(pool, 0,
+			width * scale, height * scale, stride, format);
+	wl_shm_pool_destroy(pool);
+	close(fd);
+
+	buf->size = size;
+	buf->width = width;
+	buf->height = height;
+	buf->scale = scale;
+	buf->data = data;
+	buf->surface = cairo_image_surface_create_for_data(data,
+			CAIRO_FORMAT_ARGB32, width * scale, height * scale, stride);
+	cairo_surface_set_device_scale(buf->surface, scale, scale);
+	buf->cairo = cairo_create(buf->surface);
+	buf->pango = pango_cairo_create_context(buf->cairo);
+
+	wl_buffer_add_listener(buf->buffer, &buffer_listener, buf);
+	return buf;
+}
+
+void destroy_buffer(struct pool_buffer *buffer) {
+	if (buffer->buffer) {
+		wl_buffer_destroy(buffer->buffer);
+	}
+	if (buffer->cairo) {
+		cairo_destroy(buffer->cairo);
+	}
+	if (buffer->surface) {
+		cairo_surface_destroy(buffer->surface);
+	}
+	if (buffer->pango) {
+		g_object_unref(buffer->pango);
+	}
+	if (buffer->data) {
+		munmap(buffer->data, buffer->size);
+	}
+	memset(buffer, 0, sizeof(struct pool_buffer));
+}
+
+struct pool_buffer *get_next_buffer(struct wl_shm *shm,
+		struct pool_buffer pool[static 2], int32_t width, int32_t height, int32_t scale) {
+	struct pool_buffer *buffer = NULL;
+
+	for (size_t i = 0; i < 2; ++i) {
+		if (pool[i].busy) {
+			continue;
+		}
+		buffer = &pool[i];
+	}
+
+	if (!buffer) {
+		return NULL;
+	}
+
+	if (buffer->width != width || buffer->height != height
+			|| buffer->scale != scale) {
+		destroy_buffer(buffer);
+	}
+
+	if (!buffer->buffer) {
+		if (!create_buffer(shm, buffer, width, height, scale,
+					WL_SHM_FORMAT_ARGB8888)) {
+			return NULL;
+		}
+	}
+	buffer->busy = true;
+	return buffer;
+}