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/*
* 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;
}
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