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Diffstat (limited to 'util-linux/mkswap.c')
| -rw-r--r-- | util-linux/mkswap.c | 253 |
1 files changed, 253 insertions, 0 deletions
diff --git a/util-linux/mkswap.c b/util-linux/mkswap.c new file mode 100644 index 000000000..f797d1395 --- /dev/null +++ b/util-linux/mkswap.c @@ -0,0 +1,253 @@ +#include "internal.h" +/* + * 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] device [size-in-blocks] + * + * -c for readablility checking (use it unless you are SURE!) + * + * The device may be a block device or a 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. + */ + +#include <stdio.h> +#include <unistd.h> +#include <string.h> +#include <fcntl.h> +#include <stdlib.h> +#include <sys/stat.h> +#include <sys/ioctl.h> + +#include <asm/page.h> +#include <linux/fs.h> + +#ifndef __linux__ +# define volatile +#endif + +#define TEST_BUFFER_PAGES 8 + +const char mkswap_usage[] = "mkswap [-c] partition [block-count]\n" +"\n" +"\tPrepare a disk partition to be used as a swap partition.\n" +"\tThe default block count is the size of the entire partition.\n" +"\n" +"\t-c:\tCheck for read-ability.\n" +"\tblock-count\tUse only this many blocks.\n"; + +static const char * program_name = "mkswap"; +static const char * device_name = NULL; +static int DEV = -1; +static long PAGES = 0; +static int do_check = 0; +static int badpages = 0; + + +static long bit_test_and_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; + return (r & m) != 0; +} + +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; +} + +/* + * Volatile to let gcc know that this doesn't return. When trying + * to compile this under minix, volatile gives a warning, as + * exit() isn't defined as volatile under minix. + */ +volatile void fatal_error(const char * fmt_string) +{ + fprintf(stderr,fmt_string,program_name,device_name); + exit(1); +} + +#define die(str) fatal_error("%s: " str "\n") + +static void check_blocks(int * signature_page) +{ + unsigned int current_page; + int do_seek = 1; + char buffer[PAGE_SIZE]; + + current_page = 0; + while (current_page < PAGES) { + if (!do_check) { + bit_test_and_set(signature_page,current_page++); + continue; + } else { + printf("\r%d", current_page); + } + if (do_seek && lseek(DEV,current_page*PAGE_SIZE,SEEK_SET) != + current_page*PAGE_SIZE) + die("seek failed in check_blocks"); + if ( (do_seek = (PAGE_SIZE != read(DEV, buffer, PAGE_SIZE))) ) { + bit_test_and_clear(signature_page,current_page++); + badpages++; + continue; + } + bit_test_and_set(signature_page,current_page++); + } + if (do_check) + printf("\n"); + if (badpages) + 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 count_blocks (int fd) +{ + int high, low; + + low = 0; + for (high = 1; 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; + } + valid_offset (fd, 0); + return (low + 1); +} + +static int get_size(const char *file) +{ + int fd; + int size; + + fd = open(file, O_RDWR); + if (fd < 0) { + perror(file); + exit(1); + } + if (ioctl(fd, BLKGETSIZE, &size) >= 0) { + close(fd); + return (size * 512); + } + + size = count_blocks(fd); + close(fd); + return size; +} + +int +mkswap(char *device_name, int pages, int check) + { + struct stat statbuf; + int goodpages; + int signature_page[PAGE_SIZE/sizeof(int)]; + + PAGES = pages; + do_check = check; + + memset(signature_page,0,PAGE_SIZE); + + if (device_name && !PAGES) { + PAGES = get_size(device_name) / PAGE_SIZE; + } + if (!device_name || PAGES<10) { + fprintf(stderr, + "%s: error: swap area needs to be at least %ldkB\n", + program_name, 10 * PAGE_SIZE / 1024); + /* usage(mkswap_usage); */ + exit(1); + } + if (PAGES > 8 * (PAGE_SIZE - 10)) { + PAGES = 8 * (PAGE_SIZE - 10); + fprintf(stderr, "%s: warning: truncating swap area to %ldkB\n", + program_name, PAGES * PAGE_SIZE / 1024); + } + DEV = open(device_name,O_RDWR); + if (DEV < 0 || fstat(DEV, &statbuf) < 0) { + perror(device_name); + exit(1); + } + if (!S_ISBLK(statbuf.st_mode)) + do_check=0; + else if (statbuf.st_rdev == 0x0300 || statbuf.st_rdev == 0x0340) + die("Will not try to make swapdevice on '%s'"); + check_blocks(signature_page); + if (!bit_test_and_clear(signature_page,0)) + die("fatal: first page unreadable"); + goodpages = PAGES - badpages - 1; + if (goodpages <= 0) + die("Unable to set up swap-space: unreadable"); + printf("Setting up swapspace, size = %ld bytes\n",goodpages*PAGE_SIZE); + strncpy((char*)signature_page+PAGE_SIZE-10,"SWAP-SPACE",10); + if (lseek(DEV, 0, SEEK_SET)) + die("unable to rewind swap-device"); + if (PAGE_SIZE != write(DEV, signature_page, PAGE_SIZE)) + die("unable to write signature page"); + + close(DEV); + return 0; +} + +int mkswap_main(struct FileInfo * unnecessary, int argc, char ** argv) +{ + char * tmp; + long int pages=0; + int check=0; + + if (argc && *argv) + program_name = *argv; + while (argc > 1) { + argv++; + argc--; + if (argv[0][0] != '-') + if (device_name) { + pages = strtol(argv[0],&tmp,0)>>(PAGE_SHIFT-10); + if (*tmp) { + usage(mkswap_usage); + exit(1); + } + } else + device_name = argv[0]; + else while (*++argv[0]) + switch (argv[0][0]) { + case 'c': check=1; break; + default: usage(mkswap_usage); + exit(1); + } + } + return mkswap(device_name, pages, check); +} |