view toys/other/mkswap.c @ 656:6df4ccc0acbe

Regularize command headers, update links to standards documents.
author Rob Landley <>
date Sat, 25 Aug 2012 18:08:51 -0500
parents 2986aa63a021
children 786841fdb1e0
line wrap: on
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/* vi: set sw=4 ts=4:
 * mkswap.c - Format swap device.
 * Copyright 2009 Rob Landley <>


config MKSWAP
	bool "mkswap"
	default y
	  usage: mkswap DEVICE

	  Sets up a Linux swap area on a device or file.

#include "toys.h"

void mkswap_main(void)
	int fd = xopen(*toys.optargs, O_RDWR), pagesize = sysconf(_SC_PAGE_SIZE);
	off_t len = fdlength(fd);
	unsigned int pages = (len/pagesize)-1, *swap = (unsigned int *)toybuf;

	// Write header.  Note that older kernel versions checked signature
	// on disk (not in cache) during swapon, so sync after writing.

	swap[0] = 1;
	swap[1] = pages;
	xlseek(fd, 1024, SEEK_SET);
	xwrite(fd, swap, 129*sizeof(unsigned int));
	xlseek(fd, pagesize-10, SEEK_SET);
	xwrite(fd, "SWAPSPACE2", 10);

	if (CFG_TOYBOX_FREE) close(fd);

	printf("Swapspace size: %luk\n", pages*(unsigned long)(pagesize/1024));