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-rw-r--r--usr/kinit/initrd.c204
1 files changed, 204 insertions, 0 deletions
diff --git a/usr/kinit/initrd.c b/usr/kinit/initrd.c
new file mode 100644
index 0000000..5833f2f
--- /dev/null
+++ b/usr/kinit/initrd.c
@@ -0,0 +1,204 @@
+/*
+ * Handle initrd, thus putting the backwards into backwards compatible
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <sys/stat.h>
+#include <sys/mount.h>
+#include <sys/ioctl.h>
+#include <sys/wait.h>
+#include "do_mounts.h"
+#include "kinit.h"
+#include "xpio.h"
+
+#define BUF_SIZE 65536 /* Should be a power of 2 */
+
+/*
+ * Copy the initrd to /dev/ram0, copy from the end to the beginning
+ * to avoid taking 2x the memory.
+ */
+static int rd_copy_uncompressed(int ffd, int dfd)
+{
+ char buffer[BUF_SIZE];
+ off_t bytes;
+ struct stat st;
+
+ dprintf("kinit: uncompressed initrd\n");
+
+ if (ffd < 0 || fstat(ffd, &st) || !S_ISREG(st.st_mode) ||
+ (bytes = st.st_size) == 0)
+ return -1;
+
+ while (bytes) {
+ ssize_t blocksize = ((bytes - 1) & (BUF_SIZE - 1)) + 1;
+ off_t offset = bytes - blocksize;
+
+ dprintf("kinit: copying %zd bytes at offset %llu\n",
+ blocksize, offset);
+
+ if (xpread(ffd, buffer, blocksize, offset) != blocksize ||
+ xpwrite(dfd, buffer, blocksize, offset) != blocksize)
+ return -1;
+
+ ftruncate(ffd, offset); /* Free up memory */
+ bytes = offset;
+ }
+ return 0;
+}
+
+static int rd_copy_image(const char *path)
+{
+ int ffd = open(path, O_RDONLY);
+ int rv = -1;
+ unsigned char gzip_magic[2];
+
+ if (ffd < 0)
+ goto barf;
+
+ if (xpread(ffd, gzip_magic, 2, 0) == 2 &&
+ gzip_magic[0] == 037 && gzip_magic[1] == 0213) {
+ FILE *wfd = fopen("/dev/ram0", "w");
+ if (!wfd)
+ goto barf;
+ rv = load_ramdisk_compressed(path, wfd, 0);
+ fclose(wfd);
+ } else {
+ int dfd = open("/dev/ram0", O_WRONLY);
+ if (dfd < 0)
+ goto barf;
+ rv = rd_copy_uncompressed(ffd, dfd);
+ close(dfd);
+ }
+
+barf:
+ if (ffd >= 0)
+ close(ffd);
+ return rv;
+}
+
+/*
+ * Run /linuxrc, for emulation of old-style initrd
+ */
+static int run_linuxrc(int argc, char *argv[], dev_t root_dev)
+{
+ int root_fd, old_fd;
+ pid_t pid;
+ long realroot = Root_RAM0;
+ const char *ramdisk_name = "/dev/ram0";
+ FILE *fp;
+
+ dprintf("kinit: mounting initrd\n");
+ mkdir("/root", 0700);
+ if (!mount_block(ramdisk_name, "/root", NULL, MS_VERBOSE, NULL))
+ return -errno;
+
+ /* Write the current "real root device" out to procfs */
+ dprintf("kinit: real_root_dev = %#x\n", root_dev);
+ fp = fopen("/proc/sys/kernel/real-root-dev", "w");
+ fprintf(fp, "%u", root_dev);
+ fclose(fp);
+
+ mkdir("/old", 0700);
+ root_fd = open("/", O_RDONLY|O_DIRECTORY|O_CLOEXEC, 0);
+ old_fd = open("/old", O_RDONLY|O_DIRECTORY|O_CLOEXEC, 0);
+
+ if (root_fd < 0 || old_fd < 0)
+ return -errno;
+
+ if (chdir("/root") ||
+ mount(".", "/", NULL, MS_MOVE, NULL) || chroot("."))
+ return -errno;
+
+ pid = vfork();
+ if (pid == 0) {
+ setsid();
+ /* Looks like linuxrc doesn't get the init environment
+ or parameters. Weird, but so is the whole linuxrc bit. */
+ execl("/linuxrc", "linuxrc", NULL);
+ _exit(255);
+ } else if (pid > 0) {
+ dprintf("kinit: Waiting for linuxrc to complete...\n");
+ while (waitpid(pid, NULL, 0) != pid)
+ ;
+ dprintf("kinit: linuxrc done\n");
+ } else {
+ return -errno;
+ }
+
+ if (fchdir(old_fd) ||
+ mount("/", ".", NULL, MS_MOVE, NULL) ||
+ fchdir(root_fd) || chroot("."))
+ return -errno;
+
+ close(root_fd);
+ close(old_fd);
+
+ getintfile("/proc/sys/kernel/real-root-dev", &realroot);
+
+ /* If realroot is Root_RAM0, then the initrd did any necessary work */
+ if (realroot == Root_RAM0) {
+ if (mount("/old", "/root", NULL, MS_MOVE, NULL))
+ return -errno;
+ } else {
+ mount_root(argc, argv, (dev_t) realroot, NULL);
+
+ /* If /root/initrd exists, move the initrd there, otherwise discard */
+ if (!mount("/old", "/root/initrd", NULL, MS_MOVE, NULL)) {
+ /* We're good */
+ } else {
+ int olddev = open(ramdisk_name, O_RDWR);
+ umount2("/old", MNT_DETACH);
+ if (olddev < 0 ||
+ ioctl(olddev, BLKFLSBUF, 0) ||
+ close(olddev)) {
+ fprintf(stderr,
+ "%s: Cannot flush initrd contents\n",
+ progname);
+ }
+ }
+ }
+
+ rmdir("/old");
+ return 0;
+}
+
+int initrd_load(int argc, char *argv[], dev_t root_dev)
+{
+ if (access("/initrd.image", R_OK))
+ return 0; /* No initrd */
+
+ dprintf("kinit: initrd found\n");
+
+ create_dev("/dev/ram0", Root_RAM0);
+
+ if (rd_copy_image("/initrd.image") || unlink("/initrd.image")) {
+ fprintf(stderr, "%s: initrd installation failed (too big?)\n",
+ progname);
+ return 0; /* Failed to copy initrd */
+ }
+
+ dprintf("kinit: initrd copied\n");
+
+ if (root_dev == Root_MULTI) {
+ dprintf("kinit: skipping linuxrc: incompatible with multiple roots\n");
+ /* Mounting initrd as ordinary root */
+ return 0;
+ }
+
+ if (root_dev != Root_RAM0) {
+ int err;
+ dprintf("kinit: running linuxrc\n");
+ err = run_linuxrc(argc, argv, root_dev);
+ if (err)
+ fprintf(stderr, "%s: running linuxrc: %s\n", progname,
+ strerror(-err));
+ return 1; /* initrd is root, or run_linuxrc took care of it */
+ } else {
+ dprintf("kinit: permament (or pivoting) initrd, not running linuxrc\n");
+ return 0; /* Mounting initrd as ordinary root */
+ }
+}