/* vi: set sw=4 ts=4: */ /* * mkswap.c - set up a linux swap device * * (C) 1991 Linus Torvalds. This file may be redistributed as per * the Linux copyright. */ /* * 20.12.91 - time began. Got VM working yesterday by doing this by hand. * * Usage: mkswap [-c] [-vN] [-f] device [size-in-blocks] * * -c for readability checking. (Use it unless you are SURE!) * -vN for swap areas version N. (Only N=0,1 known today.) * -f for forcing swap creation even if it would smash partition table. * * The device may be a block device or an image of one, but this isn't * enforced (but it's not much fun on a character device :-). * * Patches from jaggy@purplet.demon.co.uk (Mike Jagdis) to make the * size-in-blocks parameter optional added Wed Feb 8 10:33:43 1995. * * Version 1 swap area code (for kernel 2.1.117), aeb, 981010. * * Sparc fixes, jj@ultra.linux.cz (Jakub Jelinek), 981201 - mangled by aeb. * V1_MAX_PAGES fixes, jj, 990325. * * 1999-02-22 Arkadiusz Mi¶kiewicz * - added Native Language Support * * from util-linux -- adapted for busybox by * Erik Andersen . I ripped out Native Language * Support, made some stuff smaller, and fitted for life in busybox. * */ #include "busybox.h" #include #include #include #include /* for _IO */ #include #include /* for PAGE_SIZE and PAGE_SHIFT */ /* we also get PAGE_SIZE via getpagesize() */ static char *device_name = NULL; static int DEV = -1; static long PAGES = 0; static int check = 0; static int badpages = 0; #if ENABLE_FEATURE_MKSWAP_V0 static int version = -1; #else #define version 1 /* and make sure that we optimize away anything which would deal with checking * the kernel revision as we have v1 support only anyway. */ #undef KERNEL_VERSION #define KERNEL_VERSION(p,q,r) 1 #define get_linux_version_code() 1 #endif /* * The definition of the union swap_header uses the constant PAGE_SIZE. * Unfortunately, on some architectures this depends on the hardware model, * and can only be found at run time -- we use getpagesize(). */ static int pagesize; static unsigned int *signature_page; static struct swap_header_v1 { char bootbits[1024]; /* Space for disklabel etc. */ unsigned int swap_version; unsigned int last_page; unsigned int nr_badpages; unsigned int padding[125]; unsigned int badpages[1]; } *p; static inline void init_signature_page(void) { pagesize = getpagesize(); #ifdef PAGE_SIZE if (pagesize != PAGE_SIZE) bb_error_msg("Assuming pages of size %d", pagesize); #endif signature_page = (unsigned int *) xmalloc(pagesize); memset(signature_page, 0, pagesize); p = (struct swap_header_v1 *) signature_page; } static inline void write_signature(char *sig) { char *sp = (char *) signature_page; strncpy(sp + pagesize - 10, sig, 10); } #define V0_MAX_PAGES (8 * (pagesize - 10)) /* Before 2.2.0pre9 */ #define V1_OLD_MAX_PAGES ((0x7fffffff / pagesize) - 1) /* Since 2.2.0pre9: error if nr of pages >= SWP_OFFSET(SWP_ENTRY(0,~0UL)) with variations on #define SWP_ENTRY(type,offset) (((type) << 1) | ((offset) << 8)) #define SWP_OFFSET(entry) ((entry) >> 8) on the various architectures. Below the result - yuk. Machine pagesize SWP_ENTRY SWP_OFFSET bound+1 oldbound+2 i386 2^12 o<<8 e>>8 1<<24 1<<19 mips 2^12 o<<15 e>>15 1<<17 1<<19 alpha 2^13 o<<40 e>>40 1<<24 1<<18 m68k 2^12 o<<12 e>>12 1<<20 1<<19 sparc 2^{12,13} (o&0x3ffff)<<9 (e>>9)&0x3ffff 1<<18 1<<{19,18} sparc64 2^13 o<<13 e>>13 1<<51 1<<18 ppc 2^12 o<<8 e>>8 1<<24 1<<19 armo 2^{13,14,15} o<<8 e>>8 1<<24 1<<{18,17,16} armv 2^12 o<<9 e>>9 1<<23 1<<19 assuming that longs have 64 bits on alpha and sparc64 and 32 bits elsewhere. The bad part is that we need to know this since the kernel will refuse a swap space if it is too large. */ /* patch from jj - why does this differ from the above? */ #if defined(__alpha__) #define V1_MAX_PAGES ((1 << 24) - 1) #elif defined(__mips__) #define V1_MAX_PAGES ((1 << 17) - 1) #elif defined(__sparc_v9__) #define V1_MAX_PAGES ((3 << 29) - 1) #elif defined(__sparc__) #define V1_MAX_PAGES (pagesize == 8192 ? ((3 << 29) - 1) : ((1 << 18) - 1)) #else #define V1_MAX_PAGES V1_OLD_MAX_PAGES #endif /* man page now says: The maximum useful size of a swap area now depends on the architecture. It is roughly 2GB on i386, PPC, m68k, ARM, 1GB on sparc, 512MB on mips, 128GB on alpha and 3TB on sparc64. */ #define MAX_BADPAGES ((pagesize-1024-128*sizeof(int)-10)/sizeof(int)) static inline void bit_set(unsigned int *addr, unsigned int nr) { unsigned int r, m; addr += nr / (8 * sizeof(int)); r = *addr; m = 1 << (nr & (8 * sizeof(int) - 1)); *addr = r | m; } static int bit_test_and_clear(unsigned int *addr, unsigned int nr) { unsigned int r, m; addr += nr / (8 * sizeof(int)); r = *addr; m = 1 << (nr & (8 * sizeof(int) - 1)); *addr = r & ~m; return (r & m) != 0; } static void page_ok(int page) { if (ENABLE_FEATURE_MKSWAP_V0) { bit_set(signature_page, page); } } static void check_blocks(void) { unsigned int current_page; int do_seek = 1; char *buffer; buffer = xmalloc(pagesize); current_page = 0; while (current_page < PAGES) { if (!check && version == 0) { page_ok(current_page++); continue; } if (do_seek && lseek(DEV, current_page * pagesize, SEEK_SET) != current_page * pagesize) bb_error_msg_and_die("seek failed in check_blocks"); if ((do_seek = (pagesize != read(DEV, buffer, pagesize)))) { current_page++; if (version == 0) bit_test_and_clear(signature_page, current_page); else { if (badpages == MAX_BADPAGES) bb_error_msg_and_die("too many bad pages"); p->badpages[badpages] = current_page; } badpages++; continue; } page_ok(current_page++); } if (ENABLE_FEATURE_CLEAN_UP) free(buffer); if (badpages > 0) printf("%d bad page%s\n", badpages, (badpages==1)?"":"s"); } static long valid_offset(int fd, int offset) { char ch; if (lseek(fd, offset, 0) < 0) return 0; if (read(fd, &ch, 1) < 1) return 0; return 1; } static int find_size(int fd) { unsigned int high, low; low = 0; for (high = 1; high > 0 && valid_offset(fd, high); high *= 2) low = high; while (low < high - 1) { const int mid = (low + high) / 2; if (valid_offset(fd, mid)) low = mid; else high = mid; } return (low + 1); } /* return size in pages, to avoid integer overflow */ static inline long get_size(const char *file) { int fd; long size; fd = bb_xopen3(file, O_RDONLY, 0); if (ioctl(fd, BLKGETSIZE, &size) >= 0) { size /= pagesize / 512; } else { size = find_size(fd) / pagesize; } close(fd); return size; } int mkswap_main(int argc, char **argv) { char *tmp; struct stat statbuf; int sz; int maxpages; int goodpages; #ifdef __sparc__ int force = 0; #endif init_signature_page(); /* get pagesize */ bb_opt_complementally = "?"; /* call bb_show_usage internally */ sz = bb_getopt_ulflags(argc, argv, "+cfv:", &tmp); if (sz & 1) check = 1; #ifdef __sparc__ if (sz & 2) force = 1; #endif #if ENABLE_FEATURE_MKSWAP_V0 if (sz & 4) { version = bb_xgetlarg(tmp, 10, 0, 1); } else { if (get_linux_version_code() < KERNEL_VERSION(2, 1, 117)) version = 0; else version = 1; } #endif argv += optind; argc -= optind; goodpages = pagesize / 1024; /* cache division */ while (argc--) { if (device_name) { PAGES = bb_xgetlarg(argv[0], 0, 10, sz * goodpages) / goodpages; argc = 0; /* ignore any surplus args.. */ } else { device_name = argv[0]; sz = get_size(device_name); argv++; } } if (!device_name) { bb_error_msg_and_die("error: Nowhere to set up swap on?"); } if (!PAGES) { PAGES = sz; } #if 0 maxpages = ((version == 0) ? V0_MAX_PAGES : V1_MAX_PAGES); #else if (!version) maxpages = V0_MAX_PAGES; else if (get_linux_version_code() >= KERNEL_VERSION(2,2,1)) maxpages = V1_MAX_PAGES; else { maxpages = V1_OLD_MAX_PAGES; if (maxpages > V1_MAX_PAGES) maxpages = V1_MAX_PAGES; } #endif if (PAGES > maxpages) { PAGES = maxpages; bb_error_msg("warning: truncating swap area to %ldkB", PAGES * goodpages); } DEV = bb_xopen3(device_name, O_RDWR, 0); if (fstat(DEV, &statbuf) < 0) bb_perror_msg_and_die("%s", device_name); if (!S_ISBLK(statbuf.st_mode)) check = 0; else if (statbuf.st_rdev == 0x0300 || statbuf.st_rdev == 0x0340) bb_error_msg_and_die("Will not try to make swapdevice on '%s'", device_name); #ifdef __sparc__ if (!force && version == 0) { /* Don't overwrite partition table unless forced */ unsigned char *buffer = (unsigned char *) signature_page; unsigned short *q, sum; if (read(DEV, buffer, 512) != 512) bb_error_msg_and_die("fatal: first page unreadable"); if (buffer[508] == 0xDA && buffer[509] == 0xBE) { q = (unsigned short *) (buffer + 510); for (sum = 0; q >= (unsigned short *) buffer;) sum ^= *q--; if (!sum) { bb_error_msg("Device '%s' contains a valid Sun disklabel.\n" "This probably means creating v0 swap would destroy your partition table\n" "No swap created. If you really want to create swap v0 on that device, use\n" "the -f option to force it.", device_name); return EXIT_FAILURE; } } } #endif if (version == 0 || check) check_blocks(); if (version == 0 && !bit_test_and_clear(signature_page, 0)) bb_error_msg_and_die("fatal: first page unreadable"); if (version == 1) { p->swap_version = version; p->last_page = PAGES - 1; p->nr_badpages = badpages; } goodpages = PAGES - badpages - 1; if (goodpages <= 0) bb_error_msg_and_die("Unable to set up swap-space: unreadable"); printf("Setting up swapspace version %d, size = %ld bytes\n", version, (long) (goodpages * pagesize)); write_signature((version == 0) ? "SWAP-SPACE" : "SWAPSPACE2"); sz = ((version == 0) ? 0 : 1024); /* offset */ if (lseek(DEV, sz, SEEK_SET) != sz) bb_error_msg_and_die("unable to rewind swap-device"); goodpages = pagesize - sz; /* cache substraction */ if (write(DEV, (char *) signature_page + sz, goodpages) != goodpages) bb_error_msg_and_die("unable to write signature page"); /* * A subsequent swapon() will fail if the signature * is not actually on disk. (This is a kernel bug.) */ if (fsync(DEV)) bb_error_msg_and_die("fsync failed"); if (ENABLE_FEATURE_CLEAN_UP) { close(DEV); free(signature_page); } return EXIT_SUCCESS; }