/* Copyright (c) Dovecot authors, see top-level COPYING file */

#include "lib.h"

#include "istream.h"

#include "ostream-private.h"

#include "ostream-cmp.h"

struct cmp_ostream {

  struct ostream_private ostream;

  struct istream *input;

  bool equals;

};

static void o_stream_cmp_close(struct iostream_private *stream,

             bool close_parent)

{

  struct cmp_ostream *cstream = (struct cmp_ostream *)stream;

  if (cstream->input == NULL)

    return;

  i_stream_unref(&cstream->input);

  if (close_parent)

    o_stream_close(cstream->ostream.parent);

}

bool stream_cmp_block(struct istream *input,

          const unsigned char *data, size_t size)

{

  const unsigned char *indata;

  size_t insize, max;

  while (size > 0) {

    (void)i_stream_read_bytes(input, &indata, &insize, size);

    max = I_MIN(insize, size);

    if (insize == 0 || memcmp(data, indata, max) != 0)

      return FALSE;

    data += max;

    size -= max;

    i_stream_skip(input, max);

  }

  return TRUE;

}

static ssize_t

o_stream_cmp_sendv(struct ostream_private *stream,

       const struct const_iovec *iov, unsigned int iov_count)

{

  struct cmp_ostream *cstream = (struct cmp_ostream *)stream;

  unsigned int i;

  ssize_t ret;

  if (cstream->equals) {

    for (i = 0; i < iov_count; i++) {

      if (!stream_cmp_block(cstream->input, iov[i].iov_base,

                iov[i].iov_len)) {

        cstream->equals = FALSE;

        break;

      }

    }

  }

  if ((ret = o_stream_sendv(stream->parent, iov, iov_count)) < 0) {

    o_stream_copy_error_from_parent(stream);

    return -1;

  }

  stream->ostream.offset += ret;

  return ret;

}

struct ostream *

o_stream_create_cmp(struct ostream *output, struct istream *input)

{

  struct cmp_ostream *cstream;

  cstream = i_new(struct cmp_ostream, 1);

  cstream->ostream.sendv = o_stream_cmp_sendv;

  cstream->ostream.iostream.close = o_stream_cmp_close;

  cstream->input = input;

  cstream->equals = TRUE;

  i_stream_ref(input);

  return o_stream_create(&cstream->ostream, output,

             o_stream_get_fd(output));

}

bool o_stream_cmp_equals(struct ostream *_output)

{

  struct cmp_ostream *cstream =

    (struct cmp_ostream *)_output->real_stream;

  return cstream->equals;

}