/* 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 <inttypes.h>
#include <string.h>

#if defined (HAVE_GNUTLS) && defined (HAVE_GNUTLS_BASE64_DECODE2)
#include <gnutls/gnutls.h>
#endif

#define NBDKIT_API_VERSION 2
#include <nbdkit-plugin.h>

#include "allocator.h"
#include "cleanup.h"
#include "vector.h"

#include "data.h"
#include "format.h"

/* Data (raw|base64|data) parameter. */
static enum { NOT_SEEN, RAW, BASE64, DATA } data_seen = NOT_SEEN;
static const char *data_param;

/* size= parameter on the command line.  After configuration, it is
 * set to the final size.
 */
static int64_t size = -1;

/* Allocator. */
static struct allocator *a;
const char *allocator_type = "sparse";

/* Debug directory operations (-D data.dir=1). */
NBDKIT_DLL_PUBLIC int data_debug_dir;

/* Collect extra parameters for data $VARs. */
struct param { const char *key; const char *value; };
DEFINE_VECTOR_TYPE (param_list, struct param);
static param_list params;

/* On unload, free the sparse array. */
static void
data_unload (void)
{
  if (a)
    a->f->free (a);
}

/* Parse the base64 parameter. */
static int
read_base64 (const char *value, uint64_t *size_ret)
{
#if defined (HAVE_GNUTLS) && defined (HAVE_GNUTLS_BASE64_DECODE2)
  gnutls_datum_t in, out;
  int err;

  in.data = (unsigned char *) value;
  in.size = strlen (value);
  err = gnutls_base64_decode2 (&in, &out);
  if (err != GNUTLS_E_SUCCESS) {
    nbdkit_error ("base64: %s", gnutls_strerror (err));
    return -1;
  }

  if (a->f->write (a, out.data, out.size, 0) == -1)
    return -1;
  free (out.data);
  *size_ret = out.size;
  return 0;
#else
  nbdkit_error ("base64 is not supported in this build of the plugin");
  return -1;
#endif
}

static int
data_config (const char *key, const char *value)
{
  int64_t r;

  if (strcmp (key, "size") == 0) {
    r = nbdkit_parse_size (value);
    if (r == -1)
      return -1;
    size = r;
  }
  else if (strcmp (key, "allocator") == 0) {
    allocator_type = value;
  }
  else if (strcmp (key, "raw") == 0) {
    if (data_seen != NOT_SEEN) {
    seen_error:
      nbdkit_error ("raw|base64|data parameter must be specified exactly once");
      return -1;
    }
    data_seen = RAW;
    data_param = value;
  }
  else if (strcmp (key, "base64") == 0) {
    if (data_seen != NOT_SEEN) goto seen_error;
    data_seen = BASE64;
    data_param = value;
  }
  else if (strcmp (key, "data") == 0) {
    if (data_seen != NOT_SEEN) goto seen_error;
    data_seen = DATA;
    data_param = value;
  }
  else {
    if (param_list_append (&params,
                           (struct param){ .key = key, .value = value })
        == -1) {
      nbdkit_error ("realloc: %m");
      return -1;
    }
  }

  return 0;
}

const char *
get_extra_param (const char *name)
{
  size_t i;

  for (i = 0; i < params.len; ++i) {
    if (strcmp (params.ptr[i].key, name) == 0)
      return params.ptr[i].value;
  }

  /* XXX Allow $size to work by returning @$size. */
  return NULL;
}

/* Check the raw|base64|data was specified. */
static int
data_config_complete (void)
{
  if (data_seen == NOT_SEEN) {
    nbdkit_error ("raw|base64|data parameter was not specified");
    return -1;
  }

  if (data_seen != DATA && params.len != 0) {
    nbdkit_error ("extra parameters passed and not using data='...'");
    return -1;
  }

  return 0;
}

#define data_config_help \
  "allocator=sparse|...    Backend allocation strategy\n" \
  "base64=...              Specify base64 disk data on the command line\n" \
  "[data=]...              Specify disk data using special format\n" \
  "raw=...                 Specify raw disk data\n" \
  "size=<SIZE>             Size of the backing disk"

/* Parse raw|base64|data parameter and set the final size. */
static int
data_get_ready (void)
{
  uint64_t data_size = 0; /* Size of data specified on the command line. */

  a = create_allocator (allocator_type, data_debug_dir);
  if (a == NULL)
    return -1;

  switch (data_seen) {
  case RAW:
    data_size = strlen (data_param);
    if (a->f->write (a, data_param, data_size, 0) == -1)
      return -1;
    break;

  case BASE64:
    if (read_base64 (data_param, &data_size) == -1)
      return -1;
    break;

  case DATA:
    if (read_data_format (data_param, a, &data_size) == -1)
      return -1;
    break;

  case NOT_SEEN:
  default:
    abort ();
  }

  nbdkit_debug ("implicit data size: %" PRIi64, data_size);

  /* If size == -1 it means the size= parameter was not given so we
   * must use the data size.
   */
  if (size == -1)
    size = data_size;
  nbdkit_debug ("final size: %" PRIi64, size);

  if (a->f->set_size_hint (a, size) == -1)
    return -1;

  return 0;
}

/* Provide a way to detect if the base64 feature is supported. */
static void
data_dump_plugin (void)
{
#if defined (HAVE_GNUTLS) && defined (HAVE_GNUTLS_BASE64_DECODE2)
  printf ("data_base64=yes\n");
#endif
#ifdef HAVE_MLOCK
  printf ("mlock=yes\n");
#else
  printf ("mlock=no\n");
#endif
#ifdef HAVE_LIBZSTD
  printf ("zstd=yes\n");
#else
  printf ("zstd=no\n");
#endif
}

#define THREAD_MODEL NBDKIT_THREAD_MODEL_PARALLEL

/* Create the per-connection handle. */
static void *
data_open (int readonly)
{
  return NBDKIT_HANDLE_NOT_NEEDED;
}

/* Get the disk size. */
static int64_t
data_get_size (void *handle)
{
  return size;
}

static int
data_block_size (void *handle,
                 uint32_t *minimum, uint32_t *preferred, uint32_t *maximum)
{
  *minimum = 1;
  *preferred = a->f->preferred;
  *maximum = 0xffffffff;
  return 0;
}

/* Flush is a no-op, so advertise native FUA support */
static int
data_can_fua (void *handle)
{
  return NBDKIT_FUA_NATIVE;
}

/* Serves the same data over multiple connections. */
static int
data_can_multi_conn (void *handle)
{
  return 1;
}

/* Cache. */
static int
data_can_cache (void *handle)
{
  /* Everything is already in memory, returning this without
   * implementing .cache lets nbdkit do the correct no-op.
   */
  return NBDKIT_CACHE_NATIVE;
}

/* Fast zero. */
static int
data_can_fast_zero (void *handle)
{
  return 1;
}

/* Read data. */
static int
data_pread (void *handle, void *buf, uint32_t count, uint64_t offset,
            uint32_t flags)
{
  assert (!flags);
  return a->f->read (a, buf, count, offset);
}

/* Write data. */
static int
data_pwrite (void *handle, const void *buf, uint32_t count, uint64_t offset,
             uint32_t flags)
{
  /* Flushing, and thus FUA flag, is a no-op */
  assert ((flags & ~NBDKIT_FLAG_FUA) == 0);
  return a->f->write (a, buf, count, offset);
}

/* Zero. */
static int
data_zero (void *handle, uint32_t count, uint64_t offset, uint32_t flags)
{
  /* Flushing, and thus FUA flag, is a no-op. Assume that
   * a->f->zero generally beats writes, so FAST_ZERO is a no-op. */
  assert ((flags & ~(NBDKIT_FLAG_FUA | NBDKIT_FLAG_MAY_TRIM |
                     NBDKIT_FLAG_FAST_ZERO)) == 0);
  return a->f->zero (a, count, offset);
}

/* Trim (same as zero). */
static int
data_trim (void *handle, uint32_t count, uint64_t offset, uint32_t flags)
{
  /* Flushing, and thus FUA flag, is a no-op */
  assert ((flags & ~NBDKIT_FLAG_FUA) == 0);
  return a->f->zero (a, count, offset);
}

/* Nothing is persistent, so flush is trivially supported */
static int
data_flush (void *handle, uint32_t flags)
{
  return 0;
}

/* Extents. */
static int
data_extents (void *handle, uint32_t count, uint64_t offset,
              uint32_t flags, struct nbdkit_extents *extents)
{
  return a->f->extents (a, count, offset, extents);
}

static struct nbdkit_plugin plugin = {
  .name              = "data",
  .version           = PACKAGE_VERSION,
  .unload            = data_unload,
  .config            = data_config,
  .config_complete   = data_config_complete,
  .config_help       = data_config_help,
  .magic_config_key  = "data",
  .dump_plugin       = data_dump_plugin,
  .get_ready         = data_get_ready,
  .open              = data_open,
  .get_size          = data_get_size,
  .block_size        = data_block_size,
  .can_multi_conn    = data_can_multi_conn,
  .can_fua           = data_can_fua,
  .can_cache         = data_can_cache,
  .can_fast_zero     = data_can_fast_zero,
  .pread             = data_pread,
  .pwrite            = data_pwrite,
  .zero              = data_zero,
  .trim              = data_trim,
  .flush             = data_flush,
  .extents           = data_extents,
  /* In this plugin, errno is preserved properly along error return
   * paths from failed system calls.
   */
  .errno_is_preserved = 1,
};

NBDKIT_REGISTER_PLUGIN (plugin)