347 lines
8.2 KiB
C
347 lines
8.2 KiB
C
/*
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* fallocate - utility to use the fallocate system call
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*
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* Copyright (C) 2008-2009 Red Hat, Inc. All rights reserved.
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* Written by Eric Sandeen <sandeen@redhat.com>
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* Karel Zak <kzak@redhat.com>
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*
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* cvtnum routine taken from xfsprogs,
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* Copyright (c) 2003-2005 Silicon Graphics, Inc.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it would be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <sys/mman.h>
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#include <ctype.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <getopt.h>
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#include <limits.h>
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#include <string.h>
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#ifndef HAVE_FALLOCATE
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# include <sys/syscall.h>
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#endif
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#if defined(HAVE_LINUX_FALLOC_H) && \
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(!defined(FALLOC_FL_KEEP_SIZE) || !defined(FALLOC_FL_PUNCH_HOLE))
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# include <linux/falloc.h> /* non-libc fallback for FALLOC_FL_* flags */
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#endif
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#ifndef FALLOC_FL_KEEP_SIZE
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# define FALLOC_FL_KEEP_SIZE 1
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#endif
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#ifndef FALLOC_FL_PUNCH_HOLE
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# define FALLOC_FL_PUNCH_HOLE 2
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#endif
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#include "nls.h"
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#include "strutils.h"
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#include "c.h"
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#include "closestream.h"
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#include "xalloc.h"
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static int verbose;
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static char *filename;
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static void __attribute__((__noreturn__)) usage(FILE *out)
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{
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fputs(USAGE_HEADER, out);
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fprintf(out,
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_(" %s [options] <filename>\n"), program_invocation_short_name);
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fputs(USAGE_OPTIONS, out);
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fputs(_(" -d, --dig-holes detect and dig holes\n"), out);
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fputs(_(" -l, --length <num> length of the (de)allocation, in bytes\n"), out);
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fputs(_(" -n, --keep-size don't modify the length of the file\n"), out);
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fputs(_(" -o, --offset <num> offset of the (de)allocation, in bytes\n"), out);
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fputs(_(" -p, --punch-hole punch holes in the file\n"), out);
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fputs(_(" -v, --verbose verbose mode\n"), out);
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fputs(USAGE_SEPARATOR, out);
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fputs(USAGE_HELP, out);
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fputs(USAGE_VERSION, out);
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fprintf(out, USAGE_MAN_TAIL("fallocate(1)"));
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exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
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}
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static loff_t cvtnum(char *s)
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{
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uintmax_t x;
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if (strtosize(s, &x))
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return -1LL;
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return x;
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}
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static void xfallocate(int fd, int mode, off_t offset, off_t length)
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{
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int error;
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#ifdef HAVE_FALLOCATE
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error = fallocate(fd, mode, offset, length);
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#else
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error = syscall(SYS_fallocate, fd, mode, offset, length);
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#endif
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/*
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* EOPNOTSUPP: The FALLOC_FL_KEEP_SIZE is unsupported
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* ENOSYS: The filesystem does not support sys_fallocate
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*/
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if (error < 0) {
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if ((mode & FALLOC_FL_KEEP_SIZE) && errno == EOPNOTSUPP)
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errx(EXIT_FAILURE, _("keep size mode (-n option) unsupported"));
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err(EXIT_FAILURE, _("fallocate failed"));
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}
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}
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static int skip_hole(int fd, off_t *off)
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{
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off_t newoff;
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errno = 0;
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newoff = lseek(fd, *off, SEEK_DATA);
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/* ENXIO means that there is no more data -- probably sparse hole at
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* the end of the file */
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if (newoff < 0 && errno == ENXIO)
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return 1;
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if (newoff > *off) {
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*off = newoff;
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return 0; /* success */
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}
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return -1; /* no hole */
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}
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/* The real buffer size has to be bufsize + sizeof(uintptr_t) */
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static int is_nul(void *buf, size_t bufsize)
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{
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typedef uintptr_t word;
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void const *vp;
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char const *cbuf = buf, *cp;
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word const *wp = buf;
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/* set sentinel */
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memset((char *) buf + bufsize, '\1', sizeof(word));
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/* Find first nonzero *word*, or the word with the sentinel. */
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while (*wp++ == 0)
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continue;
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/* Find the first nonzero *byte*, or the sentinel. */
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vp = wp - 1;
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cp = vp;
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while (*cp++ == 0)
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continue;
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return cbuf + bufsize < cp;
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}
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static void dig_holes(int fd, off_t off, off_t len)
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{
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off_t end = len ? off + len : 0;
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off_t hole_start = 0, hole_sz = 0;
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off_t cache_start = 0;
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uintmax_t ct = 0;
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size_t bufsz, cachesz;
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char *buf;
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struct stat st;
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if (fstat(fd, &st) != 0)
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err(EXIT_FAILURE, _("stat failed %s"), filename);
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bufsz = st.st_blksize;
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/*
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* We don't want to call POSIX_FADV_DONTNEED to discard cached
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* data in PAGE_SIZE steps. IMHO it's overkill (too many syscalls).
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*
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* Let's assume that 1MiB (on system with 4K page size) is just
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* a good compromise.
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* -- kzak Feb-2014
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*/
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cachesz = getpagesize() * 256;
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if (lseek(fd, off, SEEK_SET) < 0)
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err(EXIT_FAILURE, _("seek on %s failed"), filename);
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/* buffer + extra space for is_nul() sentinel */
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buf = xmalloc(bufsz + sizeof(uintptr_t));
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cache_start = off;
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#if defined(POSIX_FADV_SEQUENTIAL) && defined(HAVE_POSIX_FADVISE)
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posix_fadvise(fd, off, 0, POSIX_FADV_SEQUENTIAL);
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#endif
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while (end == 0 || off < end) {
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ssize_t rsz;
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rsz = pread(fd, buf, bufsz, off);
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if (rsz < 0 && errno)
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err(EXIT_FAILURE, _("%s: read failed"), filename);
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if (end && rsz > 0 && off > end - rsz)
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rsz = end - off;
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if (rsz <= 0)
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break;
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if (is_nul(buf, rsz)) {
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if (!hole_sz) { /* new hole detected */
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int rc = skip_hole(fd, &off);
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if (rc == 0)
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continue; /* hole skipped */
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else if (rc == 1)
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break; /* end of file */
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hole_start = off;
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}
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hole_sz += rsz;
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} else if (hole_sz) {
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xfallocate(fd, FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE,
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hole_start, hole_sz);
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ct += hole_sz;
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hole_sz = hole_start = 0;
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}
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#if defined(POSIX_FADV_DONTNEED) && defined(HAVE_POSIX_FADVISE)
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/* discard cached data */
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if (off - cache_start > (off_t) cachesz) {
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size_t clen = off - cache_start;
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clen = (clen / cachesz) * cachesz;
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posix_fadvise(fd, cache_start, clen, POSIX_FADV_DONTNEED);
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cache_start = cache_start + clen;
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}
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#endif
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off += rsz;
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}
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if (hole_sz) {
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xfallocate(fd, FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE,
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hole_start, hole_sz);
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ct += hole_sz;
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}
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free(buf);
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if (verbose) {
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char *str = size_to_human_string(SIZE_SUFFIX_3LETTER | SIZE_SUFFIX_SPACE, ct);
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fprintf(stdout, _("%s: %s (%ju bytes) converted to sparse holes.\n"),
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filename, str, ct);
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free(str);
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}
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}
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int main(int argc, char **argv)
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{
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int c;
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int fd;
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int mode = 0;
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int dig = 0;
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loff_t length = -2LL;
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loff_t offset = 0;
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static const struct option longopts[] = {
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{ "help", 0, 0, 'h' },
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{ "version", 0, 0, 'V' },
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{ "keep-size", 0, 0, 'n' },
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{ "punch-hole", 0, 0, 'p' },
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{ "dig-holes", 0, 0, 'd' },
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{ "offset", 1, 0, 'o' },
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{ "length", 1, 0, 'l' },
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{ "verbose", 0, 0, 'v' },
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{ NULL, 0, 0, 0 }
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};
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setlocale(LC_ALL, "");
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bindtextdomain(PACKAGE, LOCALEDIR);
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textdomain(PACKAGE);
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atexit(close_stdout);
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while ((c = getopt_long(argc, argv, "hvVnpdl:o:", longopts, NULL)) != -1) {
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switch(c) {
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case 'h':
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usage(stdout);
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break;
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case 'V':
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printf(UTIL_LINUX_VERSION);
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return EXIT_SUCCESS;
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case 'p':
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mode |= FALLOC_FL_PUNCH_HOLE;
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/* fall through */
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case 'n':
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mode |= FALLOC_FL_KEEP_SIZE;
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break;
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case 'd':
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dig = 1;
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break;
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case 'l':
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length = cvtnum(optarg);
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break;
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case 'o':
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offset = cvtnum(optarg);
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break;
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case 'v':
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verbose++;
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break;
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default:
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usage(stderr);
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break;
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}
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}
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if (dig) {
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if (mode != 0)
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errx(EXIT_FAILURE, _("Can't use -p or -n with --dig-holes"));
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if (length == -2LL)
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length = 0;
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if (length < 0)
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errx(EXIT_FAILURE, _("invalid length value specified"));
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} else {
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if (length == -2LL)
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errx(EXIT_FAILURE, _("no length argument specified"));
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if (length <= 0)
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errx(EXIT_FAILURE, _("invalid length value specified"));
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}
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if (offset < 0)
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errx(EXIT_FAILURE, _("invalid offset value specified"));
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if (optind == argc)
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errx(EXIT_FAILURE, _("no filename specified."));
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filename = argv[optind++];
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if (optind != argc) {
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warnx(_("unexpected number of arguments"));
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usage(stderr);
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}
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fd = open(filename, O_RDWR|O_CREAT, 0644);
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if (fd < 0)
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err(EXIT_FAILURE, _("cannot open %s"), filename);
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if (dig)
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dig_holes(fd, offset, length);
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else
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xfallocate(fd, mode, offset, length);
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if (close_fd(fd) != 0)
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err(EXIT_FAILURE, _("write failed: %s"), filename);
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return EXIT_SUCCESS;
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}
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