rl: Run rlwsd

1 files changed, 50 insertions, 6 deletions

diff --git a/rushmore-linux/rlwsd/rlwsd.c b/rushmore-linux/rlwsd/rlwsd.c
index 94ebd87..0c96881 100644
--- a/rushmore-linux/rlwsd/rlwsd.c
+++ b/rushmore-linux/rlwsd/rlwsd.c
@@ -1,11 +1,55 @@
+#include <errno.h>
+#include <fcntl.h>
+// #include <linux/fb.h>
+#include <stdarg.h>
+#include <string.h>
+#include <stdio.h>
+#include <sys/uio.h>
 #include <unistd.h>
 
+static const char* tmp_fmt(const char* fmt, ...)
+{
+    static char msg[1024] = { 0 };
+    va_list va; va_start(va, fmt);
+    vsnprintf(msg, sizeof(msg), fmt, va);
+    va_end(va);
+    return msg;
+}
+
+static void spew(const char* message)
+{
+    // Kernel log is available after init
+    int kmfd = open("/dev/kmsg", O_WRONLY | O_CLOEXEC);
+
+    struct iovec msgvec[] = {
+#define STRVEC(str) { .iov_base = (void*)(str), .iov_len = __builtin_strlen(str) }
+        STRVEC("rlwsd: "),
+        STRVEC(message),
+        STRVEC("\n")
+#undef STRVEC
+    };
+    writev(kmfd, msgvec, sizeof(msgvec) / sizeof(*msgvec));
+
+    close(kmfd);
+}
+
+static void panic(const char* message)
+{
+    spew(message);
+    _exit(1); // Triggers a kernel panic since we're PID 1
+}
+
 int main(void)
 {
-	const char* msg = "[rlwsd] HELLO!\n";
-	write(1, msg, __builtin_strlen(msg));
-	for (;;)
-	{
-		pause();
-	}
+    int fd = open("/dev/fb0", O_RDWR | O_CLOEXEC);
+    if (fd < 0) {
+        panic(tmp_fmt("Failed to open /dev/fb0: %s", strerror(errno)));
+    }
+
+    const char* msg = "[rlwsd] HELLO!\n";
+    write(1, msg, __builtin_strlen(msg));
+    for (;;)
+    {
+        pause();
+    }
 }