/*

Copyright 2020 Google LLC

Use of this source code is governed by a BSD-style

license that can be found in the LICENSE file or at

https://developers.google.com/open-source/licenses/bsd

*/

#include "system.h"

#include "basics.h"

#include "blocksource.h"

#include "reftable-blocksource.h"

#include "reftable-error.h"

static void strbuf_return_block(void *b UNUSED, struct reftable_block *dest)

{

  if (dest->len)

    memset(dest->data, 0xff, dest->len);

  reftable_free(dest->data);

}

static void strbuf_close(void *b UNUSED)

{

}

static int strbuf_read_block(void *v, struct reftable_block *dest, uint64_t off,

           uint32_t size)

{

  struct strbuf *b = v;

  assert(off + size <= b->len);

  REFTABLE_CALLOC_ARRAY(dest->data, size);

  memcpy(dest->data, b->buf + off, size);

  dest->len = size;

  return size;

}

static uint64_t strbuf_size(void *b)

{

  return ((struct strbuf *)b)->len;

}

static struct reftable_block_source_vtable strbuf_vtable = {

  .size = &strbuf_size,

  .read_block = &strbuf_read_block,

  .return_block = &strbuf_return_block,

  .close = &strbuf_close,

};

void block_source_from_strbuf(struct reftable_block_source *bs,

            struct strbuf *buf)

{

  assert(!bs->ops);

  bs->ops = &strbuf_vtable;

  bs->arg = buf;

}

struct file_block_source {

  uint64_t size;

  unsigned char *data;

};

static uint64_t file_size(void *b)

{

  return ((struct file_block_source *)b)->size;

}

static void file_return_block(void *b UNUSED, struct reftable_block *dest UNUSED)

{

}

static void file_close(void *v)

{

  struct file_block_source *b = v;

  munmap(b->data, b->size);

  reftable_free(b);

}

static int file_read_block(void *v, struct reftable_block *dest, uint64_t off,

         uint32_t size)

{

  struct file_block_source *b = v;

  assert(off + size <= b->size);

  dest->data = b->data + off;

  dest->len = size;

  return size;

}

static struct reftable_block_source_vtable file_vtable = {

  .size = &file_size,

  .read_block = &file_read_block,

  .return_block = &file_return_block,

  .close = &file_close,

};

int reftable_block_source_from_file(struct reftable_block_source *bs,

            const char *name)

{

  struct file_block_source *p;

  struct stat st;

  int fd;

  fd = open(name, O_RDONLY);

  if (fd < 0) {

    if (errno == ENOENT)

      return REFTABLE_NOT_EXIST_ERROR;

    return -1;

  }

  if (fstat(fd, &st) < 0) {

    close(fd);

    return REFTABLE_IO_ERROR;

  }

  REFTABLE_CALLOC_ARRAY(p, 1);

  p->size = st.st_size;

  p->data = xmmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);

  close(fd);

  assert(!bs->ops);

  bs->ops = &file_vtable;

  bs->arg = p;

  return 0;

}