Init

1 files changed, 184 insertions, 0 deletions

diff --git a/src/buffer.c b/src/buffer.c
new file mode 100644
index 0000000..83f48ad
--- /dev/null
+++ b/src/buffer.c
@@ -0,0 +1,184 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <time.h>
+#include <sys/mman.h>
+#include <cairo/cairo.h>
+
+#include"buffer.h"
+#include"misc.h"
+
+static void randomize_string (char *str, size_t len)
+{
+	struct timespec ts;
+	clock_gettime(CLOCK_REALTIME, &ts);
+	long r = ts.tv_nsec;
+
+	for (size_t i = 0; i < len; i++, str++)
+	{
+		/* Use two byte from the current nano-second to pseudo-randomly
+		 * increase the ASCII character 'A' into another character,
+		 * which will then subsitute the character at *str.
+		 */
+		*str = (char)('A' + (r&15) + (r&16));
+		r >>= 5;
+	}
+}
+
+/* Tries to create a shared memory object and returns its file descriptor if
+ * successful.
+ */
+static bool get_shm_fd (int *fd, size_t size)
+{
+	char name[] = "/wlclock-RANDOM";
+	char *rp    = name + 9; /* Pointer to random part. */
+	size_t rl   = 6;        /* Length of random part. */
+
+	/* Try a few times to get a unique name. */
+	for (int tries = 100; tries > 0; tries--)
+	{
+		/* Make the name pseudo-random to not conflict with other
+		 * running instances of Wlclock.
+		 */
+		randomize_string(rp, rl);
+
+		/* Try to create a shared memory object. Returns -1 if the
+		 * memory object already exists.
+		 */
+		errno = 0;
+		*fd   = shm_open(name, O_RDWR | O_CREAT | O_EXCL, 0600);
+
+		/* If a shared memory object was created, set its size and
+		 * return its file descriptor.
+		 */
+		if ( *fd >= 0 )
+		{
+			shm_unlink(name);
+			if ( ftruncate(*fd, (off_t)size) < 0 )
+			{
+				close(*fd);
+				return false;
+			}
+			return true;
+		}
+
+		/* The EEXIST error means that the name is not unique and we
+		 * must try again.
+		 */
+		if ( errno != EEXIST )
+		{
+			clocklog(NULL, 0, "ERROR: shm_open: %s\n", strerror(errno));
+			return false;
+		}
+	}
+
+	return false;
+}
+
+static void buffer_handle_release (void *data, struct wl_buffer *wl_buffer)
+{
+	struct Wlclock_buffer *buffer = (struct Wlclock_buffer *)data;
+	buffer->busy                  = false;
+}
+
+static const struct wl_buffer_listener buffer_listener = {
+	.release = buffer_handle_release,
+};
+
+static bool create_buffer (struct wl_shm *shm, struct Wlclock_buffer *buffer,
+		uint32_t _w, uint32_t _h)
+{
+	int32_t w = (int32_t)_w, h = (int32_t)_h;
+
+	const enum wl_shm_format wl_fmt    = WL_SHM_FORMAT_ARGB8888;
+	const cairo_format_t     cairo_fmt = CAIRO_FORMAT_ARGB32;
+
+	int32_t stride = cairo_format_stride_for_width(cairo_fmt, w);
+	size_t   size  = (size_t)(stride * h);
+
+	buffer->w    = _w;
+	buffer->h    = _h;
+	buffer->size = size;
+
+	if ( size == 0 )
+	{
+		buffer->memory_object = NULL;
+		buffer->surface       = NULL;
+		buffer->cairo         = NULL;
+		return true;
+	}
+
+	int fd;
+	if (! get_shm_fd(&fd, size))
+		return false;
+
+	errno = 0;
+	if ( MAP_FAILED == (buffer->memory_object = mmap(NULL, size,
+					PROT_READ | PROT_WRITE, MAP_SHARED,
+					fd, 0)) )
+	{
+		close(fd);
+		clocklog(NULL, 0, "ERROR: mmap: %s\n", strerror(errno));
+		return false;
+	}
+
+	struct wl_shm_pool *pool = wl_shm_create_pool(shm, fd, (int32_t)size);
+	buffer->buffer = wl_shm_pool_create_buffer(pool, 0, w, h, stride,
+			wl_fmt);
+	wl_buffer_add_listener(buffer->buffer, &buffer_listener, buffer);
+	wl_shm_pool_destroy(pool);
+
+	close(fd);
+
+	buffer->surface = cairo_image_surface_create_for_data(
+		buffer->memory_object, cairo_fmt, w, h, stride);
+	buffer->cairo = cairo_create(buffer->surface);
+
+	return true;
+}
+
+void finish_buffer (struct Wlclock_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->memory_object)
+		munmap(buffer->memory_object, buffer->size);
+	memset(buffer, 0, sizeof(struct Wlclock_buffer));
+}
+
+bool next_buffer (struct Wlclock_buffer **buffer, struct wl_shm *shm,
+		struct Wlclock_buffer buffers[static 2], uint32_t w, uint32_t h)
+{
+	/* Check if buffers are busy and use first non-busy one, if it exists.
+	 * If all buffers are busy, exit.
+	 */
+	if (! buffers[0].busy)
+		*buffer = &buffers[0];
+	else if (! buffers[1].busy)
+		*buffer = &buffers[1];
+	else
+	{
+		clocklog(NULL, 0, "ERROR: All buffers are busy.\n");
+		*buffer = NULL;
+		return false;
+	}
+
+	/* If the buffers dimensions do not match, or if there is no wl_buffer
+	 * or if the buffer does not exist, close it and create a new one.
+	 */
+	if ( (*buffer)->w != w || (*buffer)->h != h || ! (*buffer)->buffer )
+	{
+		finish_buffer(*buffer);
+		if (! create_buffer(shm, *buffer, w, h))
+			return false;
+	}
+
+	return true;
+}