dovecot-2.1: istream-concat: Backported fixes from v2.2.

[dovecot at dovecot.org]

details:   http://hg.dovecot.org/dovecot-2.1/rev/b93e49f114e7
changeset: 15009:b93e49f114e7
user:      Timo Sirainen <tss at iki.fi>
date:      Mon Feb 03 11:37:48 2014 -0500
description:
istream-concat: Backported fixes from v2.2.
This should fix corruption with LMTP proxying when the same mail was being
sent to multiple backends.

diffstat:

 src/lib/istream-concat.c |  41 ++++++++++++++++++++++++++---------------
 1 files changed, 26 insertions(+), 15 deletions(-)

diffs (96 lines):

diff -r 0eccb40ee3c4 -r b93e49f114e7 src/lib/istream-concat.c
--- a/src/lib/istream-concat.c	Thu Jan 30 22:03:40 2014 +0100
+++ b/src/lib/istream-concat.c	Mon Feb 03 11:37:48 2014 -0500
@@ -87,7 +87,8 @@
 {
 	struct concat_istream *cstream = (struct concat_istream *)stream;
 	const unsigned char *data;
-	size_t size, pos, cur_pos, bytes_skipped, new_bytes_count;
+	size_t size, data_size, cur_data_pos, new_pos, bytes_skipped;
+	size_t new_bytes_count;
 	ssize_t ret;
 	bool last_stream;
 
@@ -101,7 +102,6 @@
 
 	if (cstream->prev_stream_left == 0) {
 		/* no need to worry about buffers, skip everything */
-		i_assert(cstream->prev_skip == 0);
 	} else if (bytes_skipped < cstream->prev_stream_left) {
 		/* we're still skipping inside buffer */
 		cstream->prev_stream_left -= bytes_skipped;
@@ -111,17 +111,21 @@
 		bytes_skipped -= cstream->prev_stream_left;
 		cstream->prev_stream_left = 0;
 	}
-	i_stream_skip(cstream->cur_input, bytes_skipped);
 	stream->pos -= bytes_skipped;
 	stream->skip -= bytes_skipped;
+	stream->buffer += bytes_skipped;
+	cstream->prev_skip = stream->skip;
+	i_stream_skip(cstream->cur_input, bytes_skipped);
 
-	cur_pos = stream->pos - stream->skip - cstream->prev_stream_left;
-	data = i_stream_get_data(cstream->cur_input, &pos);
-	if (pos > cur_pos)
+	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(cstream->cur_input, &data_size);
+	if (data_size > cur_data_pos)
 		ret = 0;
 	else {
 		/* need to read more */
-		i_assert(cur_pos == pos);
+		i_assert(cur_data_pos == data_size);
 		ret = i_stream_read(cstream->cur_input);
 		if (ret == -2 || ret == 0)
 			return ret;
@@ -145,18 +149,25 @@
 
 		stream->istream.eof = cstream->cur_input->eof && last_stream;
 		i_assert(ret != -1 || stream->istream.eof);
-		data = i_stream_get_data(cstream->cur_input, &pos);
+		data = i_stream_get_data(cstream->cur_input, &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;
-	} else if (pos == cur_pos) {
+		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;
-		pos = stream->pos;
+		new_pos = stream->pos;
 	} else {
-		new_bytes_count = pos - cur_pos;
+		/* 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_get_buffer_space(stream, new_bytes_count, &size)) {
 			stream->buffer = stream->w_buffer;
 			return -2;
@@ -166,13 +177,13 @@
 		if (new_bytes_count > size)
 			new_bytes_count = size;
 		memcpy(stream->w_buffer + stream->pos,
-		       data + cur_pos, new_bytes_count);
-		pos = stream->pos + new_bytes_count;
+		       data + cur_data_pos, new_bytes_count);
+		new_pos = stream->pos + new_bytes_count;
 	}
 
-	ret = pos > stream->pos ? (ssize_t)(pos - stream->pos) :
+	ret = new_pos > stream->pos ? (ssize_t)(new_pos - stream->pos) :
 		(ret == 0 ? 0 : -1);
-	stream->pos = pos;
+	stream->pos = new_pos;
 	cstream->prev_skip = stream->skip;
 	return ret;
 }