Initial revision

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);
+}