1 files changed, 88 insertions, 0 deletions
diff --git a/bin/gfb.c b/bin/gfb.c
new file mode 100644
index 00000000..e64efee5
--- /dev/null
+++ b/bin/gfb.c
@@ -0,0 +1,88 @@
+/* Copyright (c) 2018, June McEnroe <programble@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <err.h>
+#include <fcntl.h>
+#include <linux/fb.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sysexits.h>
+#include <termios.h>
+#include <unistd.h>
+
+extern int init(int argc, char *argv[]);
+extern void draw(uint32_t *buf, size_t xres, size_t yres);
+extern void input(char in);
+
+static uint32_t *buf;
+static struct fb_var_screeninfo info;
+
+static uint32_t saveBg;
+static void restoreBg(void) {
+    for (size_t i = 0; i < info.xres * info.yres; ++i) {
+        buf[i] = saveBg;
+    }
+}
+
+static struct termios saveTerm;
+static void restoreTerm(void) {
+    tcsetattr(STDERR_FILENO, TCSADRAIN, &saveTerm);
+}
+
+int main(int argc, char *argv[]) {
+    int error;
+
+    error = init(argc, argv);
+    if (error) return error;
+
+    const char *path = getenv("FRAMEBUFFER");
+    if (!path) path = "/dev/fb0";
+
+    int fb = open(path, O_RDWR);
+    if (fb < 0) err(EX_OSFILE, "%s", path);
+
+    error = ioctl(fb, FBIOGET_VSCREENINFO, &info);
+    if (error) err(EX_IOERR, "%s", path);
+
+    size_t size = 4 * info.xres * info.yres;
+    buf = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fb, 0);
+    if (buf == MAP_FAILED) err(EX_IOERR, "%s", path);
+
+    saveBg = buf[0];
+    atexit(restoreBg);
+
+    error = tcgetattr(STDERR_FILENO, &saveTerm);
+    if (error) err(EX_IOERR, "tcgetattr");
+    atexit(restoreTerm);
+
+    struct termios term = saveTerm;
+    term.c_lflag &= ~(ICANON | ECHO);
+    error = tcsetattr(STDERR_FILENO, TCSADRAIN, &term);
+    if (error) err(EX_IOERR, "tcsetattr");
+
+    for (;;) {
+        draw(buf, info.xres, info.yres);
+
+        char in;
+        ssize_t len = read(STDERR_FILENO, &in, 1);
+        if (len < 0) err(EX_IOERR, "read");
+        if (!len) return EX_DATAERR;
+
+        input(in);
+    }
+}