New mkswap. Small and simple. Might even work. :)
This commit is contained in:
Rob Landley
parent
534374755d
commit
d893b120ba
@ -1,397 +1,46 @@
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/* vi: set sw=4 ts=4: */
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/*
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* mkswap.c - set up a linux swap device
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/* mkswap.c - format swap device (Linux v1 only)
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*
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* (C) 1991 Linus Torvalds. This file may be redistributed as per
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* the Linux copyright.
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* Copyright 2006 Rob Landley <rob@landley.net>
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*
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* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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*/
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/*
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* 20.12.91 - time began. Got VM working yesterday by doing this by hand.
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*
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* Usage: mkswap [-c] [-vN] [-f] device [size-in-blocks]
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*
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* -c for readability checking. (Use it unless you are SURE!)
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* -vN for swap areas version N. (Only N=0,1 known today.)
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* -f for forcing swap creation even if it would smash partition table.
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*
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* The device may be a block device or an image of one, but this isn't
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* enforced (but it's not much fun on a character device :-).
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*
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* Patches from jaggy@purplet.demon.co.uk (Mike Jagdis) to make the
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* size-in-blocks parameter optional added Wed Feb 8 10:33:43 1995.
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*
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* Version 1 swap area code (for kernel 2.1.117), aeb, 981010.
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*
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* Sparc fixes, jj@ultra.linux.cz (Jakub Jelinek), 981201 - mangled by aeb.
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* V1_MAX_PAGES fixes, jj, 990325.
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*
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* 1999-02-22 Arkadiusz Mi¶kiewicz <misiek@misiek.eu.org>
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* - added Native Language Support
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*
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* from util-linux -- adapted for busybox by
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* Erik Andersen <andersen@codepoet.org>. I ripped out Native Language
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* Support, made some stuff smaller, and fitted for life in busybox.
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*
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*/
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#include <busybox.h>
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#include "busybox.h"
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#include <unistd.h>
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#include <string.h>
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#include <fcntl.h>
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#include <sys/ioctl.h> /* for _IO */
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#include <sys/utsname.h>
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#include <asm/page.h> /* for PAGE_SIZE and PAGE_SHIFT */
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/* we also get PAGE_SIZE via getpagesize() */
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static char *device_name = NULL;
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static int DEV = -1;
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static long PAGES = 0;
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static int check = 0;
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static int badpages = 0;
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#if ENABLE_FEATURE_MKSWAP_V0
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static int version = -1;
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#else
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#define version 1
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/* and make sure that we optimize away anything which would deal with checking
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* the kernel revision as we have v1 support only anyway.
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*/
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#undef KERNEL_VERSION
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#define KERNEL_VERSION(p,q,r) 1
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#define get_linux_version_code() 1
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#endif
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/*
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* The definition of the union swap_header uses the constant PAGE_SIZE.
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* Unfortunately, on some architectures this depends on the hardware model,
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* and can only be found at run time -- we use getpagesize().
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*/
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static int pagesize;
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static unsigned int *signature_page;
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static struct swap_header_v1 {
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char bootbits[1024]; /* Space for disklabel etc. */
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unsigned int swap_version;
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unsigned int last_page;
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unsigned int nr_badpages;
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unsigned int padding[125];
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unsigned int badpages[1];
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} *p;
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static inline void init_signature_page(void)
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int mkswap_main(int argc, char *argv[])
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{
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int fd, pagesize;
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off_t len;
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unsigned int hdr[129];
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// No options supported.
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if (argc!=2) bb_show_usage();
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// Figure out how big the device is and announce our intentions.
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fd = bb_xopen(argv[1],O_RDWR);
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len = fdlength(fd);
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pagesize = getpagesize();
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printf("Setting up swapspace version 1, size = %ld bytes\n", (long)(len-pagesize));
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#ifdef PAGE_SIZE
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if (pagesize != PAGE_SIZE)
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bb_error_msg("Assuming pages of size %d", pagesize);
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#endif
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signature_page = (unsigned int *) xmalloc(pagesize);
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memset(signature_page, 0, pagesize);
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p = (struct swap_header_v1 *) signature_page;
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}
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// Make a header.
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static inline void write_signature(char *sig)
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{
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char *sp = (char *) signature_page;
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memset(hdr, 0, 129 * sizeof(unsigned int));
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hdr[0] = 1;
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hdr[1] = (len / pagesize) - 1;
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strncpy(sp + pagesize - 10, sig, 10);
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}
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// Write the header. Sync to disk because some kernel versions check
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// signature on disk (not in cache) during swapon.
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#define V0_MAX_PAGES (8 * (pagesize - 10))
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/* Before 2.2.0pre9 */
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#define V1_OLD_MAX_PAGES ((0x7fffffff / pagesize) - 1)
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/* Since 2.2.0pre9:
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error if nr of pages >= SWP_OFFSET(SWP_ENTRY(0,~0UL))
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with variations on
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#define SWP_ENTRY(type,offset) (((type) << 1) | ((offset) << 8))
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#define SWP_OFFSET(entry) ((entry) >> 8)
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on the various architectures. Below the result - yuk.
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xlseek(fd, 1024, SEEK_SET);
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xwrite(fd, hdr, 129 * sizeof(unsigned int));
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xlseek(fd, pagesize-10, SEEK_SET);
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xwrite(fd, "SWAPSPACE2", 10);
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fsync(fd);
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Machine pagesize SWP_ENTRY SWP_OFFSET bound+1 oldbound+2
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i386 2^12 o<<8 e>>8 1<<24 1<<19
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mips 2^12 o<<15 e>>15 1<<17 1<<19
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alpha 2^13 o<<40 e>>40 1<<24 1<<18
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m68k 2^12 o<<12 e>>12 1<<20 1<<19
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sparc 2^{12,13} (o&0x3ffff)<<9 (e>>9)&0x3ffff 1<<18 1<<{19,18}
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sparc64 2^13 o<<13 e>>13 1<<51 1<<18
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ppc 2^12 o<<8 e>>8 1<<24 1<<19
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armo 2^{13,14,15} o<<8 e>>8 1<<24 1<<{18,17,16}
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armv 2^12 o<<9 e>>9 1<<23 1<<19
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if (ENABLE_FEATURE_CLEAN_UP) close(fd);
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assuming that longs have 64 bits on alpha and sparc64 and 32 bits elsewhere.
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The bad part is that we need to know this since the kernel will
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refuse a swap space if it is too large.
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*/
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/* patch from jj - why does this differ from the above? */
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#if defined(__alpha__)
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#define V1_MAX_PAGES ((1 << 24) - 1)
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#elif defined(__mips__)
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#define V1_MAX_PAGES ((1 << 17) - 1)
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#elif defined(__sparc_v9__)
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#define V1_MAX_PAGES ((3 << 29) - 1)
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#elif defined(__sparc__)
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#define V1_MAX_PAGES (pagesize == 8192 ? ((3 << 29) - 1) : ((1 << 18) - 1))
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#else
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#define V1_MAX_PAGES V1_OLD_MAX_PAGES
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#endif
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/* man page now says:
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The maximum useful size of a swap area now depends on the architecture.
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It is roughly 2GB on i386, PPC, m68k, ARM, 1GB on sparc, 512MB on mips,
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128GB on alpha and 3TB on sparc64.
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*/
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#define MAX_BADPAGES ((pagesize-1024-128*sizeof(int)-10)/sizeof(int))
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static inline void bit_set(unsigned int *addr, unsigned int nr)
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{
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unsigned int r, m;
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addr += nr / (8 * sizeof(int));
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r = *addr;
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m = 1 << (nr & (8 * sizeof(int) - 1));
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*addr = r | m;
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}
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static int bit_test_and_clear(unsigned int *addr, unsigned int nr)
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{
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unsigned int r, m;
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addr += nr / (8 * sizeof(int));
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r = *addr;
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m = 1 << (nr & (8 * sizeof(int) - 1));
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*addr = r & ~m;
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return (r & m) != 0;
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}
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static void page_ok(int page)
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{
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if (ENABLE_FEATURE_MKSWAP_V0) {
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bit_set(signature_page, page);
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}
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}
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static void check_blocks(void)
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{
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unsigned int current_page;
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int do_seek = 1;
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char *buffer;
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buffer = xmalloc(pagesize);
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current_page = 0;
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while (current_page < PAGES) {
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if (!check && version == 0) {
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page_ok(current_page++);
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continue;
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}
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if (do_seek && lseek(DEV, current_page * pagesize, SEEK_SET) !=
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current_page * pagesize)
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bb_error_msg_and_die("seek failed in check_blocks");
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if ((do_seek = (pagesize != read(DEV, buffer, pagesize)))) {
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current_page++;
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if (version == 0)
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bit_test_and_clear(signature_page, current_page);
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else {
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if (badpages == MAX_BADPAGES)
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bb_error_msg_and_die("too many bad pages");
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p->badpages[badpages] = current_page;
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}
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badpages++;
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continue;
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}
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page_ok(current_page++);
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}
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if (ENABLE_FEATURE_CLEAN_UP)
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free(buffer);
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if (badpages > 0)
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printf("%d bad page%s\n", badpages, (badpages==1)?"":"s");
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}
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static long valid_offset(int fd, int offset)
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{
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char ch;
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if (lseek(fd, offset, 0) < 0)
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return 0;
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if (read(fd, &ch, 1) < 1)
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return 0;
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return 1;
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}
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static int find_size(int fd)
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{
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unsigned int high, low;
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low = 0;
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for (high = 1; high > 0 && valid_offset(fd, high); high *= 2)
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low = high;
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while (low < high - 1) {
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const int mid = (low + high) / 2;
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if (valid_offset(fd, mid))
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low = mid;
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else
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high = mid;
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}
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return (low + 1);
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}
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/* return size in pages, to avoid integer overflow */
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static inline long get_size(const char *file)
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{
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int fd;
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long size;
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fd = bb_xopen3(file, O_RDONLY, 0);
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if (ioctl(fd, BLKGETSIZE, &size) >= 0) {
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size /= pagesize / 512;
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} else {
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size = find_size(fd) / pagesize;
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}
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close(fd);
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return size;
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}
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int mkswap_main(int argc, char **argv)
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{
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char *tmp;
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struct stat statbuf;
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int sz;
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int maxpages;
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int goodpages;
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#ifdef __sparc__
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int force = 0;
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#endif
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init_signature_page(); /* get pagesize */
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bb_opt_complementally = "?"; /* call bb_show_usage internally */
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sz = bb_getopt_ulflags(argc, argv, "+cfv:", &tmp);
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if (sz & 1)
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check = 1;
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#ifdef __sparc__
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if (sz & 2)
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force = 1;
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#endif
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#if ENABLE_FEATURE_MKSWAP_V0
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if (sz & 4) {
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version = bb_xgetlarg(tmp, 10, 0, 1);
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} else {
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if (get_linux_version_code() < KERNEL_VERSION(2, 1, 117))
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version = 0;
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else
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version = 1;
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}
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#endif
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argv += optind;
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argc -= optind;
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goodpages = pagesize / 1024; /* cache division */
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while (argc--) {
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if (device_name) {
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PAGES = bb_xgetlarg(argv[0], 0, 10, sz * goodpages) / goodpages;
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argc = 0; /* ignore any surplus args.. */
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} else {
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device_name = argv[0];
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sz = get_size(device_name);
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argv++;
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}
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}
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if (!device_name) {
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bb_error_msg_and_die("error: Nowhere to set up swap on?");
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}
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if (!PAGES) {
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PAGES = sz;
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}
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if (!version)
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maxpages = V0_MAX_PAGES;
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else if (get_linux_version_code() >= KERNEL_VERSION(2,2,1))
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maxpages = V1_MAX_PAGES;
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else {
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maxpages = V1_OLD_MAX_PAGES;
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if (maxpages > V1_MAX_PAGES)
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maxpages = V1_MAX_PAGES;
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}
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if (PAGES > maxpages) {
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PAGES = maxpages;
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bb_error_msg("warning: truncating swap area to %ldkB",
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PAGES * goodpages);
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}
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DEV = bb_xopen3(device_name, O_RDWR, 0);
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if (fstat(DEV, &statbuf) < 0)
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bb_perror_msg_and_die("%s", device_name);
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if (!S_ISBLK(statbuf.st_mode))
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check = 0;
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else if (statbuf.st_rdev == 0x0300 || statbuf.st_rdev == 0x0340)
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bb_error_msg_and_die("Will not try to make swapdevice on '%s'", device_name);
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#ifdef __sparc__
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if (!force && version == 0) {
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/* Don't overwrite partition table unless forced */
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unsigned char *buffer = (unsigned char *) signature_page;
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unsigned short *q, sum;
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if (read(DEV, buffer, 512) != 512)
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bb_error_msg_and_die("fatal: first page unreadable");
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if (buffer[508] == 0xDA && buffer[509] == 0xBE) {
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q = (unsigned short *) (buffer + 510);
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for (sum = 0; q >= (unsigned short *) buffer;)
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sum ^= *q--;
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if (!sum) {
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bb_error_msg("Device '%s' contains a valid Sun disklabel.\n"
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"This probably means creating v0 swap would destroy your partition table\n"
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"No swap created. If you really want to create swap v0 on that device, use\n"
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"the -f option to force it.", device_name);
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return EXIT_FAILURE;
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}
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}
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}
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#endif
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if (version == 0 || check)
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check_blocks();
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if (version == 0 && !bit_test_and_clear(signature_page, 0))
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bb_error_msg_and_die("fatal: first page unreadable");
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if (version == 1) {
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p->swap_version = version;
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p->last_page = PAGES - 1;
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p->nr_badpages = badpages;
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}
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goodpages = PAGES - badpages - 1;
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if (goodpages <= 0)
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bb_error_msg_and_die("Unable to set up swap-space: unreadable");
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printf("Setting up swapspace version %d, size = %ld bytes\n",
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version, (long) (goodpages * pagesize));
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write_signature((version == 0) ? "SWAP-SPACE" : "SWAPSPACE2");
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sz = ((version == 0) ? 0 : 1024); /* offset */
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if (lseek(DEV, sz, SEEK_SET) != sz)
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bb_error_msg_and_die("unable to rewind swap-device");
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goodpages = pagesize - sz; /* cache substraction */
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if (write(DEV, (char *) signature_page + sz, goodpages)
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!= goodpages)
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bb_error_msg_and_die("unable to write signature page");
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/*
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* A subsequent swapon() will fail if the signature
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* is not actually on disk. (This is a kernel bug.)
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*/
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if (fsync(DEV))
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bb_error_msg_and_die("fsync failed");
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if (ENABLE_FEATURE_CLEAN_UP) {
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close(DEV);
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free(signature_page);
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}
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return EXIT_SUCCESS;
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}
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