istream-chain.c revision 1a3254b83ba00315cfc47d3c6e99e837914594cf
/* Copyright (c) 2003-2013 Dovecot authors, see the included COPYING file */
#include "lib.h"
#include "llist.h"
#include "istream-private.h"
#include "istream-chain.h"
struct chain_istream;
struct istream_chain_link {
struct istream_chain_link *prev, *next;
struct istream *stream;
bool eof;
};
struct istream_chain {
struct istream_chain_link *head, *tail;
struct chain_istream *stream;
};
struct chain_istream {
struct istream_private istream;
size_t prev_stream_left, prev_skip;
struct istream_chain chain;
};
static void ATTR_NULL(2)
i_stream_chain_append_internal(struct istream_chain *chain,
struct istream *stream)
{
struct istream_chain_link *link;
if (stream == NULL && chain->tail != NULL && chain->tail->stream == NULL)
return;
link = i_new(struct istream_chain_link, 1);
link->stream = stream;
link->eof = stream == NULL;
if (stream != NULL)
i_stream_ref(stream);
if (chain->head == NULL && stream != NULL) {
if (chain->stream->istream.max_buffer_size == 0) {
chain->stream->istream.max_buffer_size =
stream->real_stream->max_buffer_size;
} else {
i_stream_set_max_buffer_size(stream,
chain->stream->istream.max_buffer_size);
}
}
DLLIST2_APPEND(&chain->head, &chain->tail, link);
}
void i_stream_chain_append(struct istream_chain *chain, struct istream *stream)
{
i_stream_chain_append_internal(chain, stream);
}
void i_stream_chain_append_eof(struct istream_chain *chain)
{
i_stream_chain_append_internal(chain, NULL);
}
static void
i_stream_chain_set_max_buffer_size(struct iostream_private *stream,
size_t max_size)
{
struct chain_istream *cstream = (struct chain_istream *)stream;
struct istream_chain_link *link = cstream->chain.head;
cstream->istream.max_buffer_size = max_size;
while (link != NULL) {
if (link->stream != NULL)
i_stream_set_max_buffer_size(link->stream, max_size);
link = link->next;
}
}
static void i_stream_chain_destroy(struct iostream_private *stream)
{
struct chain_istream *cstream = (struct chain_istream *)stream;
struct istream_chain_link *link = cstream->chain.head;
while (link != NULL) {
struct istream_chain_link *next = link->next;
if (link->stream != NULL)
i_stream_unref(&link->stream);
i_free(link);
link = next;
}
i_free(cstream->istream.w_buffer);
}
static void i_stream_chain_read_next(struct chain_istream *cstream)
{
struct istream_chain_link *link = cstream->chain.head;
struct istream *prev_input;
const unsigned char *data;
size_t data_size, size, cur_data_pos;
i_assert(link != NULL && link->stream != NULL);
i_assert(link->stream->eof);
prev_input = link->stream;
data = i_stream_get_data(prev_input, &data_size);
DLLIST2_REMOVE(&cstream->chain.head, &cstream->chain.tail, link);
i_free(link);
/* a) we have more streams, b) we have EOF, c) we need to wait
for more streams */
link = cstream->chain.head;
if (link != NULL && link->stream != NULL)
i_stream_seek(link->stream, 0);
if (cstream->prev_stream_left > 0) {
/* we've already buffered some of the prev_input. continue
appending the rest to it. */
cur_data_pos = cstream->istream.pos -
(cstream->istream.skip + cstream->prev_stream_left);
i_assert(cur_data_pos <= data_size);
data += cur_data_pos;
data_size -= cur_data_pos;
} else {
cstream->istream.pos = 0;
cstream->istream.skip = 0;
cstream->prev_stream_left = 0;
}
/* we already verified that the data size is less than the
maximum buffer size */
if (data_size > 0) {
if (!i_stream_try_alloc(&cstream->istream, data_size, &size))
i_unreached();
i_assert(size >= data_size);
}
memcpy(cstream->istream.w_buffer + cstream->istream.pos,
data, data_size);
cstream->istream.pos += data_size;
cstream->prev_stream_left += data_size;
i_stream_skip(prev_input, i_stream_get_data_size(prev_input));
i_stream_unref(&prev_input);
}
static ssize_t i_stream_chain_read(struct istream_private *stream)
{
struct chain_istream *cstream = (struct chain_istream *)stream;
struct istream_chain_link *link = cstream->chain.head;
const unsigned char *data;
size_t size, data_size, cur_data_pos, new_pos, bytes_skipped;
size_t new_bytes_count;
ssize_t ret;
if (link != NULL && link->eof) {
stream->istream.eof = TRUE;
return -1;
}
i_assert(stream->skip >= cstream->prev_skip);
bytes_skipped = stream->skip - cstream->prev_skip;
if (cstream->prev_stream_left == 0) {
/* no need to worry about buffers, skip everything */
} else if (bytes_skipped < cstream->prev_stream_left) {
/* we're still skipping inside buffer */
cstream->prev_stream_left -= bytes_skipped;
bytes_skipped = 0;
} else {
/* done with the buffer */
bytes_skipped -= cstream->prev_stream_left;
cstream->prev_stream_left = 0;
}
stream->pos -= bytes_skipped;
stream->skip -= bytes_skipped;
stream->buffer += bytes_skipped;
cstream->prev_skip = stream->skip;
if (link == NULL) {
i_assert(bytes_skipped == 0);
return 0;
}
i_stream_skip(link->stream, bytes_skipped);
i_assert(stream->pos >= stream->skip + cstream->prev_stream_left);
cur_data_pos = stream->pos - (stream->skip + cstream->prev_stream_left);
data = i_stream_get_data(link->stream, &data_size);
if (data_size > cur_data_pos)
ret = 0;
else {
/* need to read more */
i_assert(cur_data_pos == data_size);
ret = i_stream_read(link->stream);
if (ret == -2 || ret == 0)
return ret;
if (ret == -1) {
if (link->stream->stream_errno != 0) {
stream->istream.stream_errno =
link->stream->stream_errno;
return -1;
}
/* EOF of this stream, go to next stream */
i_stream_chain_read_next(cstream);
cstream->prev_skip = stream->skip;
return i_stream_chain_read(stream);
}
/* we read something */
data = i_stream_get_data(link->stream, &data_size);
}
if (cstream->prev_stream_left == 0) {
/* we can point directly to the current stream's buffers */
stream->buffer = data;
stream->pos -= stream->skip;
stream->skip = 0;
new_pos = data_size;
} else if (data_size == cur_data_pos) {
/* nothing new read */
i_assert(ret == 0 || ret == -1);
stream->buffer = stream->w_buffer;
new_pos = stream->pos;
} else {
/* we still have some of the previous stream left. merge the
new data with it. */
i_assert(data_size > cur_data_pos);
new_bytes_count = data_size - cur_data_pos;
if (!i_stream_try_alloc(stream, new_bytes_count, &size)) {
stream->buffer = stream->w_buffer;
return -2;
}
stream->buffer = stream->w_buffer;
if (new_bytes_count > size)
new_bytes_count = size;
memcpy(stream->w_buffer + stream->pos,
data + cur_data_pos, new_bytes_count);
new_pos = stream->pos + new_bytes_count;
}
ret = new_pos > stream->pos ? (ssize_t)(new_pos - stream->pos) :
(ret == 0 ? 0 : -1);
stream->pos = new_pos;
cstream->prev_skip = stream->skip;
return ret;
}
struct istream *i_stream_create_chain(struct istream_chain **chain_r)
{
struct chain_istream *cstream;
cstream = i_new(struct chain_istream, 1);
cstream->chain.stream = cstream;
cstream->istream.max_buffer_size = 256;
cstream->istream.iostream.destroy = i_stream_chain_destroy;
cstream->istream.iostream.set_max_buffer_size =
i_stream_chain_set_max_buffer_size;
cstream->istream.read = i_stream_chain_read;
cstream->istream.istream.readable_fd = FALSE;
cstream->istream.istream.blocking = FALSE;
cstream->istream.istream.seekable = FALSE;
*chain_r = &cstream->chain;
return i_stream_create(&cstream->istream, NULL, -1);
}