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sh-blockdev.c
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/* sh-blockdev.c - Block device functions for g13-syshelp
* Copyright (C) 2015 Werner Koch
*
* This file is part of GnuPG.
*
* GnuPG is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* GnuPG is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <https://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <errno.h>
#include <assert.h>
#include <limits.h>
#include "g13-syshelp.h"
#include <assuan.h>
#include "../common/i18n.h"
#include "../common/exectool.h"
#include "keyblob.h"
#ifndef HAVE_STRTOULL
# error building this tool requires strtoull(3)
#endif
#ifndef ULLONG_MAX
# error ULLONG_MAX missing
#endif
/* Return the size measured in the number of 512 byte sectors for the
block device NAME. */
gpg_error_t
sh_blockdev_getsz (const char *name, unsigned long long *r_nblocks)
{
gpg_error_t err;
const char *argv[3];
char *result;
*r_nblocks = 0;
argv[0] = "--getsz";
argv[1] = name;
argv[2] = NULL;
err = gnupg_exec_tool ("/sbin/blockdev", argv, NULL, &result, NULL);
if (!err)
{
gpg_err_set_errno (0);
*r_nblocks = strtoull (result, NULL, 10);
if (*r_nblocks == ULLONG_MAX && errno)
{
err = gpg_error_from_syserror ();
*r_nblocks = 0;
}
xfree (result);
}
return err;
}
/* Return 0 if the device NAME looks like an empty partition. */
gpg_error_t
sh_is_empty_partition (const char *name)
{
gpg_error_t err;
const char *argv[6];
char *buffer;
estream_t fp;
char *p;
size_t nread;
argv[0] = "-o";
argv[1] = "value";
argv[2] = "-s";
argv[3] = "UUID";
argv[4] = name;
argv[5] = NULL;
err = gnupg_exec_tool ("/sbin/blkid", argv, NULL, &buffer, NULL);
if (err)
return gpg_error (GPG_ERR_FALSE);
if (*buffer)
{
/* There seems to be an UUID - thus we have a file system. */
xfree (buffer);
return gpg_error (GPG_ERR_FALSE);
}
xfree (buffer);
argv[0] = "-o";
argv[1] = "value";
argv[2] = "-s";
argv[3] = "PARTUUID";
argv[4] = name;
argv[5] = NULL;
err = gnupg_exec_tool ("/sbin/blkid", argv, NULL, &buffer, NULL);
if (err)
return gpg_error (GPG_ERR_FALSE);
if (!*buffer)
{
/* If there is no PARTUUID we assume that name has already a
mapped partition. */
xfree (buffer);
return gpg_error (GPG_ERR_FALSE);
}
xfree (buffer);
/* As a safeguard we require that the first 32k of a partition are
all zero before we assume the partition is empty. */
buffer = xtrymalloc (32 * 1024);
if (!buffer)
return gpg_error_from_syserror ();
fp = es_fopen (name, "rb,samethread");
if (!fp)
{
err = gpg_error_from_syserror ();
log_error ("error opening '%s': %s\n", name, gpg_strerror (err));
xfree (buffer);
return gpg_error (GPG_ERR_FALSE);
}
if (es_read (fp, buffer, 32 * 1024, &nread))
err = gpg_error_from_syserror ();
else if (nread != 32 *1024)
err = gpg_error (GPG_ERR_TOO_SHORT);
else
err = 0;
es_fclose (fp);
if (err)
{
log_error ("error reading the first 32 KiB from '%s': %s\n",
name, gpg_strerror (err));
xfree (buffer);
return err;
}
for (p=buffer; nread && !*p; nread--, p++)
;
xfree (buffer);
if (nread)
return gpg_error (GPG_ERR_FALSE); /* No all zeroes. */
return 0;
}

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Storage Handle
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