/* This is the source for linuxrc. * * It mounts the dos, win or winnt partition and associates the image file * \linux\linuxdsk.img with the loop device loop0. * If \linux\linuxswp.img exists it is associated with loop1. * * It is reported to run at least on linux kernel 2.4.28 and 2.6.9. * * You create the initrd like above, but you only have this on it. * * drwxr-xr-x 2 root root 4096 2005-01-22 18:00 dev/ * crw--w--w- 1 root tty 5, 1 2005-01-22 18:00 dev/console * brw-rw---- 1 root disk 3, 1 2005-01-22 18:00 dev/hda1 * brw-rw---- 1 root disk 7, 0 2005-01-22 18:00 dev/loop0 * brw-rw---- 1 root disk 7, 1 2005-01-22 18:00 dev/loop1 * -rwx------ 1 root root 23544 2005-01-22 18:00 linuxrc * drwxr-xr-x 2 root root 4096 2005-01-22 18:00 mnt/ * lrwxrwxrwx 1 root root 8 2005-01-22 18:00 win -> dev/hda1 * * In the above example I have a win9x partition with \linux\linuxdsk.img * on /dev/hda1, so I make a link called win to it 'ln -sf dev/hda1 win'. * * If it were a dos partition it would be 'ln -sf dev/hda1 dos'. * If it were a ntfs partition it would be 'ln -sf dev/hda1 winnt'. * * CAVE: Unlike in the 1.x versions the LINK (dos,win,winnt) HAS TO BE IN / * * * DEVFS: * ====== * * If You are using devfs the directory structure should be the following: * * drwxr-xr-x 2 root root 4096 2005-01-22 18:00 dev/ * -rwx------ 1 root root 23480 2005-01-22 18:00 linuxrc * drwxr-xr-x 2 root root 4096 2005-01-22 18:00 mnt/ * lrwxrwxrwx 1 root root 21 2005-01-22 18:00 win -> dev/discs/disc0/part1 * * * I took the original file from The Loopback Root Filesystem HOWTO * * by Andrew M. Bishop, amb@gedanken.demon.co.uk * v1.1.2, 23 Mar 2000 * * v1.1.11, 7 Sep 2002 * Kent Robotti * * v1.2.0, 31 Oct 2004 * Bodo Giannone * * v2.0.0, 22 Jan 2005 * Bodo Giannone * * * You can compile it this way. * gcc -Os -mcpu=i386 -D_FILE_OFFSET_BITS=64 -static -s -o linuxrc linuxrc.c * * It does compile also with uClibc (a very small libc) * with the command line from above. * http://www.uclibc.org * * You could use a smaller static libc, called dietlibc. * http://www.fefe.de/dietlibc/ * * dietlibc# make * dietlibc/bin-i386# ./diet gcc -Os -m386 -D_FILE_OFFSET_BITS=64 \ * -static -s -o linuxrc linuxrc.c */ #include #include #include #include #include #include #undef dev_t #define dev_t __kernel_dev_t #include #undef dev_t void die(char *s) { write(2,s,strlen(s)); } int set_loop(const char *device, const char *file, int offset, int loopro) { struct loop_info loopinfo; int fd, ffd, mode, i; char *pass; mode = loopro ? O_RDONLY : O_RDWR; if ((ffd = open (file, mode)) < 0 && !loopro && (errno != EROFS || (ffd = open (file, mode = O_RDONLY)) < 0)) { perror (file); return 0; } if ((fd = open (device, mode)) < 0) { perror (device); return 0; } loopro = (mode == O_RDONLY); memset(&loopinfo, 0, sizeof(loopinfo)); strncpy(loopinfo.lo_name, file, LO_NAME_SIZE); loopinfo.lo_name[LO_NAME_SIZE-1] = 0; loopinfo.lo_offset = offset; loopinfo.lo_encrypt_key_size = 0; if (ioctl(fd, LOOP_SET_FD, ffd) < 0) { perror("ioctl: LOOP_SET_FD"); exit(1); } if (ioctl(fd, LOOP_SET_STATUS, &loopinfo) < 0) { (void) ioctl(fd, LOOP_CLR_FD, 0); perror("ioctl: LOOP_SET_STATUS"); exit(1); } close(fd); close(ffd); return 1; } int check_loop(void) { int i,notmounted; FILE *distfile; char *loop0; char *loop1; while (1) { distfile=fopen("/mnt/linux/linuxdsk.img","r"); if (distfile==NULL) { die("\n\tERROR!\tCould not find \\linux\\linuxdsk.img on the system!\n"); die("\n\t\tPress Ctrl-Alt-Del to reboot!\n"); umount("/mnt"); pause(); exit(1); } break; } fclose(distfile); umask(0); loop0="/dev/loop0"; /* Does /dev/loop0 exist? If not, check /dev/loop/0 and if not again, create it! */ distfile=fopen("/dev/loop0","r"); if (distfile==NULL) { distfile=fopen("/dev/loop/0","r"); if (distfile==NULL) { mknod("/dev/loop0",0660|S_IFBLK,7 * 256 + 0); distfile=fopen("/dev/loop0","r"); if (distfile==NULL) { die("\n\tERROR!\tNeither /dev/loop0 nor /dev/loop/0\n"); die("\t\texists and creating failed!\n"); die("\n\t\tPress Ctrl-Alt-Del to reboot!\n"); pause(); exit(1); } } else loop0="/dev/loop/0"; } fclose(distfile); if(!(set_loop(loop0,"/mnt/linux/linuxdsk.img",0,0))) { die("\n\tERROR!\tCan't associate \\linux\\linuxdsk.img\n"); die("\t\twith the loop device loop0!\n"); die("\n\t\tPress Ctrl-Alt-Del to reboot!\n"); umount("/mnt"); pause(); exit(1); } distfile=fopen("/mnt/linux/linuxswp.img","r"); if (distfile==NULL) { die("\nINITRD: No swapfile present!\n"); } else { fclose(distfile); loop1="/dev/loop1"; /* Does /dev/loop1 exist? If not, check /dev/loop/0 and if not again, create it! */ distfile=fopen("/dev/loop1","r"); if (distfile==NULL) { distfile=fopen("/dev/loop/1","r"); if (distfile==NULL) { mknod("/dev/loop1",0660|S_IFBLK,7 * 256 + 1); distfile=fopen("/dev/loop1","r"); if (distfile==NULL) { loop1=NULL; die("\n\tERROR!\tNeither /dev/loop1 nor /dev/loop/1\n"); die("\t\texists and creating failed!\n"); die("\t\tNo swap device on loop1!\n\n"); } else fclose(distfile); } else { loop1="/dev/loop/1"; fclose(distfile); } } else fclose(distfile); if (!(loop1==NULL)) if(!(set_loop(loop1,"/mnt/linux/linuxswp.img",0,0))) { die("\n\tERROR!\tCan't associate \\linux\\linuxswp.img\n"); die("\t\twith the loop device loop1!\n"); die("\t\tNo swap device on loop1!\n\n"); } } exit(0); } int loopdos(void) { int i,notmounted; while (1) { notmounted=mount("/dos","/mnt","msdos",MS_MGC_VAL | MS_NOEXEC,"quiet",0); if (!notmounted) break; else die("\n\tERROR!\tCould not mount the dos partition!\n"); die("\n\t\tPress Ctrl-Alt-Del to reboot!\n"); pause(); exit(1); } die("INITRD: Mounted dos partition under /initrd/mnt directory...\n"); check_loop(); } int loopwin(void) { int i,notmounted; while (1) { notmounted=mount("/win","/mnt","vfat",MS_MGC_VAL | MS_NOEXEC,"quiet",0); if (!notmounted) break; else die("\n\tERROR!\tCould not mount the win partition!\n"); die("\n\t\tPress Ctrl-Alt-Del to reboot!\n"); pause(); exit(1); } die("INITRD: Mounted win partition under /initrd/mnt directory...\n"); check_loop(); } int loopwinnt(void) { int i,notmounted; while (1) { // notmounted=mount("/dev/winnt","/mnt","ntfs",MS_MGC_VAL | MS_NOEXEC,"quiet",0); notmounted=mount("/winnt","/mnt","ntfs",MS_MGC_VAL | MS_NOEXEC,0); if (!notmounted) break; else die("\n\tERROR!\tCould not mount the winnt partition!\n"); die("\n\t\tPress Ctrl-Alt-Del to reboot!\n"); pause(); exit(1); } die("INITRD: Mounted winnt partition under /initrd/mnt directory...\n"); check_loop(); } int main(void) { int i,notmounted; FILE *distfile; distfile=fopen("/dos","r"); if (!(distfile==NULL)) { fclose(distfile); loopdos(); } else { distfile=fopen("/win","r"); if (!(distfile==NULL)) { fclose(distfile); loopwin(); } else { distfile=fopen("/winnt","r"); if (!(distfile==NULL)) { fclose(distfile); loopwinnt(); } else { die("\n\tERROR!\tCould not find a device /dos, /win,\n"); die("\t\tor /winnt to mount!\n"); // die("\n\tERROR!\tCould not find a device /dos, /win, or /winnt to mount!\n"); die("\n\t\tPress Ctrl-Alt-Del to reboot!\n"); pause(); exit(1); } } } } /* End of linuxrc.c */