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/* Copyright (c) 2020 Dovecot authors, see the included COPYING file */
#include "lib.h"
#include "istream-private.h"
#include "compression.h"
struct decompress_istream {
struct istream_private istream;
struct istream *compressed_input;
struct istream *decompressed_input;
enum istream_decompress_flags flags;
};
static void copy_compressed_input_error(struct decompress_istream *zstream)
{
struct istream_private *stream = &zstream->istream;
stream->istream.stream_errno = zstream->compressed_input->stream_errno;
stream->istream.eof = zstream->compressed_input->eof;
if (zstream->compressed_input->stream_errno != 0) {
io_stream_set_error(&stream->iostream, "%s",
i_stream_get_error(&zstream->compressed_input->real_stream->istream));
}
}
static void copy_decompressed_input_error(struct decompress_istream *zstream)
{
struct istream_private *stream = &zstream->istream;
stream->istream.stream_errno = zstream->decompressed_input->stream_errno;
stream->istream.eof = zstream->decompressed_input->eof;
if (zstream->decompressed_input->stream_errno != 0) {
io_stream_set_error(&stream->iostream, "%s",
i_stream_get_error(&zstream->decompressed_input->real_stream->istream));
}
}
static void
i_stream_decompress_close(struct iostream_private *_stream, bool close_parent)
{
struct istream_private *stream =
container_of(_stream, struct istream_private, iostream);
struct decompress_istream *zstream =
container_of(stream, struct decompress_istream, istream);
if (zstream->decompressed_input != NULL)
i_stream_close(zstream->decompressed_input);
if (close_parent)
i_stream_close(zstream->compressed_input);
}
static void
i_stream_decompress_destroy(struct iostream_private *_stream)
{
struct istream_private *stream =
container_of(_stream, struct istream_private, iostream);
struct decompress_istream *zstream =
container_of(stream, struct decompress_istream, istream);
i_stream_unref(&zstream->decompressed_input);
i_stream_unref(&zstream->compressed_input);
}
static int
i_stream_decompress_not_compressed(struct decompress_istream *zstream)
{
if ((zstream->flags & ISTREAM_DECOMPRESS_FLAG_TRY) == 0) {
zstream->istream.istream.stream_errno = EINVAL;
io_stream_set_error(&zstream->istream.iostream,
"Stream isn't compressed");
return -1;
} else {
zstream->decompressed_input = zstream->compressed_input;
i_stream_ref(zstream->decompressed_input);
return 1;
}
}
static int i_stream_decompress_detect(struct decompress_istream *zstream)
{
const struct compression_handler *handler;
ssize_t ret;
ret = i_stream_read(zstream->compressed_input);
handler = compression_detect_handler(zstream->compressed_input);
if (handler == NULL) {
switch (ret) {
case -1:
if (zstream->compressed_input->stream_errno != 0) {
copy_compressed_input_error(zstream);
return -1;
}
/* fall through */
case -2:
/* we've read a full buffer or we reached EOF -
the stream isn't compressed */
return i_stream_decompress_not_compressed(zstream);
case 0:
return 0;
default:
if (!zstream->istream.istream.blocking)
return 0;
return i_stream_decompress_detect(zstream);
}
}
if (handler->create_istream == NULL) {
zstream->istream.istream.stream_errno = EINVAL;
io_stream_set_error(&zstream->istream.iostream,
"Compression handler %s not supported", handler->name);
return -1;
}
zstream->decompressed_input =
handler->create_istream(zstream->compressed_input);
return 1;
}
static ssize_t i_stream_decompress_read(struct istream_private *stream)
{
struct decompress_istream *zstream =
container_of(stream, struct decompress_istream, istream);
ssize_t ret;
size_t pos;
if (zstream->decompressed_input == NULL) {
if ((ret = i_stream_decompress_detect(zstream)) <= 0)
return ret;
}
i_stream_seek(zstream->decompressed_input, stream->istream.v_offset);
stream->pos -= stream->skip;
stream->skip = 0;
stream->buffer = i_stream_get_data(zstream->decompressed_input, &pos);
if (pos > stream->pos)
ret = 0;
else do {
ret = i_stream_read_memarea(zstream->decompressed_input);
copy_decompressed_input_error(zstream);
stream->buffer = i_stream_get_data(zstream->decompressed_input,
&pos);
} while (pos <= stream->pos && ret > 0);
if (ret == -2)
return -2;
if (pos <= stream->pos)
ret = ret == 0 ? 0 : -1;
else
ret = (ssize_t)(pos - stream->pos);
stream->pos = pos;
i_assert(ret != -1 || stream->istream.eof ||
stream->istream.stream_errno != 0);
return ret;
}
static void i_stream_decompress_reset(struct istream_private *stream)
{
stream->skip = stream->pos = 0;
stream->istream.v_offset = 0;
stream->istream.eof = FALSE;
}
static void
i_stream_decompress_seek(struct istream_private *stream,
uoff_t v_offset, bool mark)
{
struct decompress_istream *zstream =
container_of(stream, struct decompress_istream, istream);
if (zstream->decompressed_input == NULL) {
if (!i_stream_nonseekable_try_seek(stream, v_offset))
i_panic("seeking backwards before detecting compression format");
} else {
i_stream_decompress_reset(stream);
stream->istream.v_offset = v_offset;
if (mark)
i_stream_seek_mark(zstream->decompressed_input, v_offset);
else
i_stream_seek(zstream->decompressed_input, v_offset);
copy_decompressed_input_error(zstream);
}
}
static void i_stream_decompress_sync(struct istream_private *stream)
{
struct decompress_istream *zstream =
container_of(stream, struct decompress_istream, istream);
i_stream_decompress_reset(stream);
if (zstream->decompressed_input != NULL)
i_stream_sync(zstream->decompressed_input);
}
static int i_stream_decompress_stat(struct istream_private *stream, bool exact)
{
struct decompress_istream *zstream =
container_of(stream, struct decompress_istream, istream);
const struct stat *st;
if (!exact) {
if (i_stream_stat(zstream->compressed_input, exact, &st) < 0) {
copy_compressed_input_error(zstream);
return -1;
}
stream->statbuf = *st;
return 0;
}
if (zstream->decompressed_input == NULL) {
(void)i_stream_read(&stream->istream);
if (zstream->decompressed_input == NULL) {
if (stream->istream.stream_errno == 0) {
zstream->istream.istream.stream_errno = EINVAL;
io_stream_set_error(&zstream->istream.iostream,
"Stream compression couldn't be detected during stat");
}
return -1;
}
}
if (i_stream_stat(zstream->decompressed_input, exact, &st) < 0) {
copy_decompressed_input_error(zstream);
return -1;
}
i_stream_decompress_reset(stream);
stream->statbuf = *st;
return 0;
}
struct istream *
i_stream_create_decompress(struct istream *input,
enum istream_decompress_flags flags)
{
struct decompress_istream *zstream;
zstream = i_new(struct decompress_istream, 1);
zstream->compressed_input = input;
zstream->flags = flags;
i_stream_ref(input);
zstream->istream.iostream.close = i_stream_decompress_close;
zstream->istream.iostream.destroy = i_stream_decompress_destroy;
zstream->istream.max_buffer_size = input->real_stream->max_buffer_size;
zstream->istream.read = i_stream_decompress_read;
zstream->istream.seek = i_stream_decompress_seek;
zstream->istream.sync = i_stream_decompress_sync;
zstream->istream.stat = i_stream_decompress_stat;
zstream->istream.istream.readable_fd = FALSE;
zstream->istream.istream.blocking = input->blocking;
zstream->istream.istream.seekable = input->seekable;
struct istream *ret = i_stream_create(&zstream->istream, NULL,
i_stream_get_fd(input), 0);
/* input isn't used as our parent istream, so need to copy the stream
name to preserve it. */
i_stream_set_name(ret, i_stream_get_name(input));
return ret;
}
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