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/* nbdkit
* Copyright Red Hat
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* * Neither the name of Red Hat nor the names of its contributors may be
* used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <stdbool.h>
#include <assert.h>
#include <errno.h>
#include <nbdkit-filter.h>
#include "minmax.h"
/* IGNORE is defined as a macro in Windows headers files ... */
#ifdef IGNORE
#undef IGNORE
#endif
static enum ZeroMode {
NONE,
EMULATE,
NOTRIM,
PLUGIN,
} zeromode;
static enum FastZeroMode {
DEFAULT,
SLOW,
IGNORE,
NOFAST,
} fastzeromode;
static int
nozero_config (nbdkit_next_config *next, nbdkit_backend *nxdata,
const char *key, const char *value)
{
if (strcmp (key, "zeromode") == 0) {
if (strcmp (value, "emulate") == 0)
zeromode = EMULATE;
else if (strcmp (value, "notrim") == 0)
zeromode = NOTRIM;
else if (strcmp (value, "plugin") == 0)
zeromode = PLUGIN;
else if (strcmp (value, "none") != 0) {
nbdkit_error ("unknown zeromode '%s'", value);
return -1;
}
return 0;
}
if (strcmp (key, "fastzeromode") == 0) {
if (strcmp (value, "none") == 0)
fastzeromode = NOFAST;
else if (strcmp (value, "ignore") == 0)
fastzeromode = IGNORE;
else if (strcmp (value, "slow") == 0)
fastzeromode = SLOW;
else if (strcmp (value, "default") != 0) {
nbdkit_error ("unknown fastzeromode '%s'", value);
return -1;
}
return 0;
}
return next (nxdata, key, value);
}
#define nozero_config_help \
"zeromode=<MODE> One of 'none' (default), 'emulate', 'notrim',\n" \
" 'plugin'.\n" \
"fastzeromode=<MODE> One of 'default', 'none', 'slow', 'ignore'.\n"
/* Check that desired mode is supported by plugin. */
static int
nozero_prepare (nbdkit_next *next, void *handle,
int readonly)
{
int r;
/* If we are opened readonly, this filter has no impact */
if (readonly)
return 0;
if (zeromode == NOTRIM || zeromode == PLUGIN) {
r = next->can_zero (next);
if (r == -1)
return -1;
if (!r) {
nbdkit_error ("zeromode '%s' requires plugin zero support",
zeromode == NOTRIM ? "notrim" : "plugin");
return -1;
}
}
return 0;
}
/* Advertise desired WRITE_ZEROES mode. */
static int
nozero_can_zero (nbdkit_next *next, void *handle)
{
switch (zeromode) {
case NONE:
return NBDKIT_ZERO_NONE;
case EMULATE:
return NBDKIT_ZERO_EMULATE;
default:
return next->can_zero (next);
}
}
/* Advertise desired FAST_ZERO mode. */
static int
nozero_can_fast_zero (nbdkit_next *next,
void *handle)
{
if (zeromode == NONE)
return 0;
if (zeromode != EMULATE && fastzeromode == DEFAULT)
return next->can_fast_zero (next);
return fastzeromode != NOFAST;
}
static int
nozero_zero (nbdkit_next *next,
void *handle, uint32_t count, uint64_t offs, uint32_t flags,
int *err)
{
assert (zeromode != NONE && zeromode != EMULATE);
if (flags & NBDKIT_FLAG_FAST_ZERO) {
assert (fastzeromode != NOFAST);
if (fastzeromode == SLOW) {
*err = ENOTSUP;
return -1;
}
if (fastzeromode == IGNORE)
flags &= ~NBDKIT_FLAG_FAST_ZERO;
}
if (zeromode == NOTRIM)
flags &= ~NBDKIT_FLAG_MAY_TRIM;
return next->zero (next, count, offs, flags, err);
}
static struct nbdkit_filter filter = {
.name = "nozero",
.longname = "nbdkit nozero filter",
.config = nozero_config,
.config_help = nozero_config_help,
.prepare = nozero_prepare,
.can_zero = nozero_can_zero,
.can_fast_zero = nozero_can_fast_zero,
.zero = nozero_zero,
};
NBDKIT_REGISTER_FILTER (filter)
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