Hi,
I have tried to implement the "initramfs buffer spec -- third draft" by hpa
and Al Viro.
It isn't complete yet, because off the following unresolved topics:
1. For the moment it only supports files,dirs and symlinks.
2. It still needs the "RAM disk" and "initrd" support compiled in the Kernel.
3. I haven't tried to support hardlinks.
4. Since i use the ramdisk for decompression the cpio image must be a
multiple of BLOCK_SIZE bytes.
5. The cpio crc field is ignored.
I have done this only for testing if the "initramfs buffer spec -- third
draft" suffers all requirements. And to give a starting point for
implementing this. The patch works for linux 2.5.9 - 2.5.13.
The only problem i found is that after a "TRAILER!!!" cpio (per default)
align on a 512 bytes boundary, not 4 bytes.
I also have an idea about the "mounting the real root over the ramfs root"
thing, is it/could it be possible to mark an filesystem as "unmount on
closing the last used file", similary to how autofs does it ?
This could also be usefull for removal media.
(don't blame me if this is stupid, i'm only a human).
cu, Christian Koenig. (and sorry for my poor English)
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diff -ubNr linux-2.5.9.orig/drivers/block/Config.in linux-2.5.9.new/drivers/block/Config.in
--- linux-2.5.9.orig/drivers/block/Config.in Tue Apr 23 00:28:23 2002
+++ linux-2.5.9.new/drivers/block/Config.in Sun Apr 28 14:47:37 2002
@@ -46,5 +46,6 @@
int ' Default RAM disk size' CONFIG_BLK_DEV_RAM_SIZE 4096
fi
dep_bool ' Initial RAM disk (initrd) support' CONFIG_BLK_DEV_INITRD $CONFIG_BLK_DEV_RAM
+dep_bool ' Initial RAM fs (initramfs) support' CONFIG_BLK_DEV_INITRAMFS $CONFIG_BLK_DEV_INITRD
endmenu
diff -ubNr linux-2.5.9.orig/include/linux/initramfs.h linux-2.5.9.new/include/linux/initramfs.h
--- linux-2.5.9.orig/include/linux/initramfs.h Thu Jan 1 01:00:00 1970
+++ linux-2.5.9.new/include/linux/initramfs.h Thu Apr 25 02:38:36 2002
@@ -0,0 +1,25 @@
+#ifndef _LINUX_INITRAMFS_H
+#define _LINUX_INITRAMFS_H
+
+struct cpio_header {
+ char c_magic[6]; //The string "070701" or "070702"
+ char c_ino[8]; //File inode number
+ char c_mode[8]; //File mode and permissions
+ char c_uid[8]; //File uid
+ char c_gid[8]; //File gid
+ char c_nlink[8]; //Number of links
+ char c_mtime[8]; //Modification time
+ char c_filesize[8]; //Size of data field
+ char c_maj[8]; //Major part of file device number
+ char c_min[8]; //Minor part of file device number
+ char c_rmaj[8]; //Major part of device node reference
+ char c_rmin[8]; //Minor part of device node reference
+ char c_namesize[8]; //Length of filename, including final \0
+ char c_chksum[8]; //Checksum of data field if c_magic is 070702;
+};
+
+#define CPIO_MAGIC "070701"
+#define CPIO_MAGIC_CRC "070702"
+#define CPIO_TRAILER "TRAILER!!!"
+
+#endif
diff -ubNr linux-2.5.9.orig/init/do_mounts.c linux-2.5.9.new/init/do_mounts.c
--- linux-2.5.9.orig/init/do_mounts.c Tue Apr 23 00:28:49 2002
+++ linux-2.5.9.new/init/do_mounts.c Sat May 4 19:12:57 2002
@@ -17,6 +17,7 @@
#include <linux/minix_fs.h>
#include <linux/ext2_fs.h>
#include <linux/romfs_fs.h>
+#include <linux/initramfs.h>
#define BUILD_CRAMDISK
@@ -34,6 +35,9 @@
asmlinkage long sys_ioctl(int fd, int cmd, unsigned long arg);
#ifdef CONFIG_BLK_DEV_INITRD
+#ifdef CONFIG_BLK_DEV_INITRAMFS
+static off_t initramfs_size = 0;
+#endif
unsigned int real_root_dev; /* do_proc_dointvec cannot handle kdev_t */
static int __initdata mount_initrd = 1;
@@ -414,6 +418,178 @@
static int __init crd_load(int in_fd, int out_fd);
+#ifdef CONFIG_BLK_DEV_INITRAMFS
+
+static unsigned int __init ascii2int(const char *ascii)
+{
+ unsigned int res = 0;
+ int i;
+ for(i=0;i<8;i++) {
+ if(ascii[i] >= '0' && ascii[i] <= '9')
+ res += (ascii[i] - '0') << (4 * (7-i));
+ else if(ascii[i] >= 'a' && ascii[i] <= 'f')
+ res += (ascii[i] - 'a' + 10) << (4 * (7-i));
+ else if(ascii[i] >= 'A' && ascii[i] <= 'F')
+ res += (ascii[i] - 'A' + 10) << (4 * (7-i));
+ else {
+ printk("INITRAMFS: ASCII field in CPIO header contains illegar char!\n");
+ return res;
+ }
+ }
+ return res;
+}
+
+static unsigned int __init align_cpio(unsigned long pos)
+{
+ if (pos & 3)
+ return (pos & ~3) + 4;
+ return pos;
+}
+
+static int __init initramfs_magic(struct cpio_header *header)
+{
+ if (!strncmp(header->c_magic,CPIO_MAGIC,strlen(CPIO_MAGIC)))
+ return 1;
+ if (!strncmp(header->c_magic,CPIO_MAGIC,strlen(CPIO_MAGIC_CRC))) {
+ return 1;
+ }
+ return 0;
+}
+
+static int __init do_initramfs(void *name)
+{
+ int file_count = 0;
+ int in_fd;
+ off_t cur = 0;
+ char *buf;
+
+ in_fd = open(name, O_RDONLY, 0);
+ if (in_fd < 0) {
+ return 0;
+ }
+
+ buf = kmalloc(BLOCK_SIZE, GFP_KERNEL);
+ if (!buf)
+ goto out;
+
+ sys_chdir("/root");
+ sys_chroot(".");
+
+ while(cur < initramfs_size) {
+ struct cpio_header header;
+ char *filename;
+ int out_fd;
+ long filesize;
+ long bytes_read;
+
+ cur = align_cpio(cur);
+ lseek(in_fd, cur, 0);
+ if(read(in_fd, (void *)&header, sizeof (struct cpio_header)) <= 0) {
+ printk(KERN_NOTICE "INITRAMFS: EOF reached aborting extraction!\n");
+ goto out;
+ }
+ cur += sizeof (struct cpio_header);
+
+ if (!initramfs_magic(&header)) {
+ printk(KERN_NOTICE "INITRAMFS: No valid CPIO header found aborting extraction!\n");
+ goto out;
+ }
+
+ filename = kmalloc(ascii2int(header.c_namesize), GFP_KERNEL);
+ filesize = ascii2int(header.c_filesize);
+
+ lseek(in_fd, cur, 0);
+ if(read(in_fd, filename, ascii2int(header.c_namesize)) <= 0) {
+ printk(KERN_NOTICE "INITRAMFS: EOF reached aborting extraction!\n");
+ goto out;
+ }
+ cur += ascii2int(header.c_namesize);
+
+
+ printk("INITRAMFS: FileName: %s Size:%ld\n",filename,filesize);
+ cur = align_cpio(cur);
+ lseek(in_fd, cur, 0);
+ cur += filesize;
+
+ switch (ascii2int(header.c_mode) & S_IFMT) {
+ case S_IFREG: {
+ out_fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, ascii2int(header.c_mode));
+ if (out_fd < 0) {
+ printk("INITRAMFS: Error opening out file %d\n",out_fd);
+ kfree(filename);
+ goto out;
+ }
+ while(filesize) {
+ bytes_read = read(in_fd, buf, (filesize < BLOCK_SIZE) ? filesize : BLOCK_SIZE);
+ if(bytes_read < 0) {
+ printk(KERN_NOTICE "INITRAMFS: EOF reached aborting extraction!\n");
+ kfree(filename);
+ goto out;
+ }
+ write(out_fd, buf, bytes_read);
+ filesize -= bytes_read;
+ }
+ close(out_fd);
+ break;
+ }
+ case S_IFDIR: {
+ sys_mkdir(filename, ascii2int(header.c_mode) & ~S_IFMT);
+ break;
+ }
+ case S_IFLNK: {
+ bytes_read = read(in_fd, buf, (filesize < BLOCK_SIZE) ? filesize : BLOCK_SIZE);
+ buf[bytes_read] = 0;
+ sys_symlink(buf,filename);
+ break;
+ }
+ case 0: {
+ if(strcmp(filename,CPIO_TRAILER) == 0)
+ while((read(in_fd, buf, 1) == 1) && (*buf == 0) && (cur < initramfs_size))
+ cur++;
+ }
+ }
+ kfree(filename);
+ file_count++;
+ }
+ kfree(buf);
+out:
+ close(in_fd);
+ return file_count;
+}
+
+static int __init initramfs_load_image(char *name)
+{
+ int pid,i,fd;
+ unsigned char *buf;
+
+ buf = kmalloc(BLOCK_SIZE, GFP_KERNEL);
+ if (buf == 0)
+ return 0;
+
+ fd = open(name, O_RDONLY, 0);
+ if (fd < 0) {
+ kfree(buf);
+ return 0;
+ }
+ read(fd, buf, BLOCK_SIZE);
+ close(fd);
+
+ if (!initramfs_magic((struct cpio_header *)buf))
+ return 0;
+
+ printk("INITRAMFS: CPIO Image found starting extraction....\n");
+ sys_mount("ramfs", "/root", "ramfs", 0, NULL);
+
+ pid = kernel_thread(do_initramfs, name, SIGCHLD);
+ if (pid > 0) {
+ while (pid != wait(&i))
+ yield();
+ }
+ return i;
+}
+
+#endif
+
/*
* This routine tries to find a RAM disk image to load, and returns the
* number of blocks to read for a non-compressed image, 0 if the image
@@ -472,6 +648,17 @@
goto done;
}
+#ifdef CONFIG_BLK_DEV_INITRAMFS
+ /* check for cpio header */
+ if (initramfs_magic((struct cpio_header *)buf)) {
+ printk(KERN_NOTICE
+ "RAMDISK: cpio header found at block %d\n",
+ start_block);
+ nblocks = (initrd_end - initrd_start)>>BLOCK_SIZE_BITS;
+ goto done;
+ }
+#endif
+
/*
* Read block 1 to test for minix and ext2 superblock
*/
@@ -615,6 +802,9 @@
kfree(buf);
successful_load:
+#ifdef CONFIG_BLK_DEV_INITRAMFS
+ initramfs_size = lseek(out_fd, 0, 1);
+#endif
res = 1;
done:
close(in_fd);
@@ -754,6 +944,7 @@
int i, pid;
create_dev("/dev/root.old", ram0, NULL);
+ if(!initramfs_load_image("/dev/root.old"))
mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
sys_mkdir("/old", 0700);
sys_chdir("/old");
--------------Boundary-00=_7FRL7BBIOOPOA1OPA5R3--
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