Missing shmtest.c

Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 134 insertions, 0 deletions

diff --git a/shmtest.c b/shmtest.c
new file mode 100644
index 0000000..0ec8a3c
--- /dev/null
+++ b/shmtest.c
@@ -0,0 +1,134 @@
+/*
+ * Copyright © 2013 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * 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, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include <stdio.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <sys/mman.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <signal.h>
+#include <fcntl.h>
+
+int
+make_shm(int size)
+{
+	char	template[] = "/run/shm/shmfd-XXXXXX";
+	int	fd = mkstemp(template);
+
+	if (fd < 0)
+		return fd;
+	unlink(template);
+	ftruncate(fd, size);
+	return fd;
+}
+
+void *
+map_shm(int fd, int size)
+{
+	void	*addr;
+	addr = mmap (NULL, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
+	if (addr == MAP_FAILED) {
+		close (fd);
+		exit(1);
+	}
+	return addr;
+}
+
+void
+paint(uint32_t *base, int width, int height, int forward)
+{
+	int	x, y;
+	uint8_t	r, g, b;
+
+	for (y = 0; y < height; y++) {
+		for (x = 0; x < width; x++) {
+			r = x * 256 / width;
+			g = 255 - r;
+			if (forward)
+				b = y * 256 / height;
+			else
+				b = (255 - y) * 256 / height;
+			base[y * width + x] = (r << 16) | (g << 8) | b;
+		}
+	}
+}
+
+#define	WIDTH	128
+#define HEIGHT	128
+
+int	parent_fd;
+void	*parent_addr;
+int	parent_size;
+void	*fault_addr;
+
+void bus_handler(int sig, siginfo_t *info, void *param)
+{
+	int	zero_fd;
+	void	*ret;
+
+	fault_addr = info->si_addr;
+	write(2, "bus error\n", 10);
+	munmap(parent_addr, parent_size);
+	close(parent_fd);
+	zero_fd = open("/dev/zero", 2);
+
+	ret = mmap(parent_addr, parent_size, PROT_READ|PROT_WRITE, MAP_PRIVATE, zero_fd, 0);
+	if (ret != parent_addr) {
+		write(2, "bus remap failed\n", 18);
+		exit(1);
+	}
+	close(zero_fd);
+}
+
+int
+main (int argc, char **argv)
+{
+	int			fd;
+	void			*addr;
+	uint32_t		size = WIDTH * HEIGHT * 4;
+	struct sigaction	act;
+
+	fd = make_shm(size);	/* some memory */
+
+	switch (fork()) {
+	case -1:
+		perror("fork failed");
+		exit(1);
+	case 0:
+		addr = map_shm(fd, size);
+		sleep(1);
+		ftruncate(fd, 0);
+		break;
+	default:
+		parent_fd = fd;
+		act.sa_sigaction = bus_handler;
+		act.sa_flags = SA_SIGINFO;
+		sigaction(SIGBUS, &act, NULL);
+		addr = map_shm(fd, size);
+		parent_addr = addr;
+		parent_size = size;
+		sleep(2);
+		paint(addr, WIDTH, HEIGHT, 0);
+		printf ("painted\n");
+		printf ("map addr: %p\n", addr);
+		printf ("fault addr: %p\n", fault_addr);
+	}
+	exit(0);
+}