rl: Beef up init

2 files changed, 64 insertions, 13 deletions

diff --git a/rushmore-linux/rl.sh b/rushmore-linux/rl.sh
index 2f7ecae..39614bc 100755
--- a/rushmore-linux/rl.sh
+++ b/rushmore-linux/rl.sh
@@ -23,5 +23,4 @@ echo "Building initramfs"
 (cd "$ROOTFS_DIR" && find . -print0 | cpio --null -ov --format=newc) > "$BUILD_DIR/initramfs.cpio"
 
 echo "Running QEMU (do CTRL+A then X to quit)"
-sleep 1
 qemu-system-x86_64 -kernel linux/arch/x86/boot/bzImage -initrd "$BUILD_DIR/initramfs.cpio" -append "console=ttyS0" -nographic
\ No newline at end of file
diff --git a/rushmore-linux/rlinit/rlinit.c b/rushmore-linux/rlinit/rlinit.c
index 21cf2af..4ab06db 100644
--- a/rushmore-linux/rlinit/rlinit.c
+++ b/rushmore-linux/rlinit/rlinit.c
@@ -1,24 +1,76 @@
+#include <errno.h>
+#include <fcntl.h>
 #include <unistd.h>
 #include <sys/mount.h>
+#include <sys/uio.h>
 #include <sys/wait.h>
 
+static void write_str(int fd, const char* str)
+{
+    write(fd, str, __builtin_strlen(str));
+}
+
+static void error(const char* message)
+{
+    // Attempt to spew to kernel log
+    int kmfd = open("/dev/kmsg", O_WRONLY | O_CLOEXEC);
+    if (kmfd >= 0) {
+        write_str(kmfd, message);
+        close(kmfd);
+    }
+
+    _exit(1); // Kernel panic
+}
+#define ERROR(message) error("[rlinit] " message)
+
+static bool mount_required(const char* src, const char* tgt, const char* fs)
+{
+    // EBUSY means already mounted, which is ok
+    return mount(src, tgt, fs, 0, 0) >= 0 || errno == EBUSY;
+}
+
 int main(void)
 {
-    mount("proc", "/proc", "proc", 0, 0);
-    mount("sysfs", "/sys", "sysfs", 0, 0);
-    mount("devtmpfs", "/dev", "devtmpfs", 0, 0);
+#if 0
+    // First, spew a message to tty to signal we at least made it this far
+    {
+        const char* hello = "rlinit: Initialization started\n";
+        write(1, hello, __builtin_strlen(hello));
+    }
+#endif
 
-    write(1, "rlinit: starting rlwsd\n", 23);
+    // Mount /dev first, as /dev/kmsg is useful for debugging errors
+    // @@ include errno in error messages
+    if (!mount_required("devtmpfs", "/dev", "devtmpfs")) {
+        ERROR("Failed to mount /dev\n");
+    }
+    if (!mount_required("proc", "/proc", "proc")) {
+        ERROR("Failed to mount /proc\n");
+    }
+    if (!mount_required("sysfs", "/sys", "sysfs")) {
+        ERROR("Failed to mount /sys\n");
+    }
 
-    pid_t pid = fork();
-    if (pid == 0) {
-        char *argv[] = { (char*)"/rlwsd", 0 };
-        execv(argv[0], argv);
-        _exit(127);
+    // Write to kernel log
+    {
+        int kmfd = open("/dev/kmsg", O_WRONLY | O_CLOEXEC);
+        if (kmfd >= 0) {
+            const char* hello = "<6>Rushmore Linux - Nothing is beyond our reach.\n";
+            write(kmfd, hello, __builtin_strlen(hello));
+            close(kmfd);
+        }
     }
 
-    int st = 0;
-    waitpid(pid, &st, 0);
-    write(1, "rlinit: rlwsd exited\n", 21);
+    // pid_t pid = fork();
+    // if (pid == 0) {
+    //     char *argv[] = { (char*)"/rlwsd", 0 };
+    //     execv(argv[0], argv);
+    //     _exit(127);
+    // }
+
+    // int st = 0;
+    // waitpid(pid, &st, 0);
+    // write(1, "rlinit: rlwsd exited\n", 21);
+
     for (;;) pause();
 }