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Diffstat (limited to 'historic/mkswap.c')
| -rw-r--r-- | historic/mkswap.c | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/historic/mkswap.c b/historic/mkswap.c new file mode 100644 index 000000000..bb4e2249e --- /dev/null +++ b/historic/mkswap.c @@ -0,0 +1,212 @@ +/* + * 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. + * + * Usuage: 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 <linux/mm.h> + +#ifndef __GNUC__ +#error "needs gcc for the bitop-__asm__'s" +#endif + +#ifndef __linux__ +#define volatile +#endif + +#define TEST_BUFFER_PAGES 8 + +static char * program_name = "mkswap"; +static char * device_name = NULL; +static int DEV = -1; +static long PAGES = 0; +static int check = 0; +static int badpages = 0; + +static char signature_page[PAGE_SIZE]; + +#define bitop(name,op) \ +static inline int name(char * addr,unsigned int nr) \ +{ \ +int __res; \ +__asm__ __volatile__("bt" op " %1,%2; adcl $0,%0" \ +:"=g" (__res) \ +:"r" (nr),"m" (*(addr)),"0" (0)); \ +return __res; \ +} + +bitop(bit,"") +bitop(setbit,"s") +bitop(clrbit,"r") + +/* + * 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 usage() fatal_error("Usage: %s [-c] /dev/name [blocks]\n") +#define die(str) fatal_error("%s: " str "\n") + +void check_blocks(void) +{ + unsigned int current_page; + int do_seek = 1; + static char buffer[PAGE_SIZE]; + + current_page = 0; + while (current_page < PAGES) { + if (!check) { + setbit(signature_page,current_page++); + continue; + } + 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))) { + clrbit(signature_page,current_page++); + badpages++; + continue; + } + setbit(signature_page,current_page++); + } + 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 main(int argc, char ** argv) +{ + char * tmp; + struct stat statbuf; + int goodpages; + + memset(signature_page,0,PAGE_SIZE); + if (argc && *argv) + program_name = *argv; + while (argc-- > 1) { + argv++; + if (argv[0][0] != '-') + if (device_name) { + PAGES = strtol(argv[0],&tmp,0)>>2; + if (*tmp) + usage(); + } else + device_name = argv[0]; + else while (*++argv[0]) + switch (argv[0][0]) { + case 'c': check=1; break; + default: usage(); + } + } + if (device_name && !PAGES) { + PAGES = get_size(device_name) / PAGE_SIZE; + } + if (!device_name || PAGES<10) + usage(); + if (PAGES > 32688) /* 130752 blocks */ + PAGES=32688; +#if 0 + if (PAGES > 32768) + PAGES=32768; +#endif + DEV = open(device_name,O_RDWR); + if (DEV < 0 || fstat(DEV, &statbuf) < 0) { + perror(device_name); + exit(1); + } + if (!S_ISBLK(statbuf.st_mode)) + check=0; + else if (statbuf.st_rdev == 0x0300 || statbuf.st_rdev == 0x0340) + die("Will not try to make swapdevice on '%s'"); + check_blocks(); + if (!clrbit(signature_page,0)) + die("fatal: first page unreadable"); + goodpages = PAGES - badpages - 1; + if (!goodpages) + die("Unable to set up swap-space: unreadable"); + printf("Setting up swapspace, size = %d bytes\n",goodpages*PAGE_SIZE); + strncpy(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"); + return 0; +} |