From: Timo Sirainen <timo.sirainen@open-xchange.com>
Date: Wed, 9 Sep 2020 09:03:31 +0000 (+0300)
Subject: lib: ostream-buffer: Return 0 as the used size, not the destination buffer size
X-Git-Tag: 2.3.13~233
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=48083d9e7fdbe257b0be33043ecf0ca87489eef9;p=thirdparty%2Fdovecot%2Fcore.git

lib: ostream-buffer: Return 0 as the used size, not the destination buffer size

This allows using ostream-buffer in places that previously would think that
the ostream buffer needed to be flushed because its buffer size was too
large.

This also changes o_stream_get_buffer_avail_size() to always return the
ostream max buffer size.
---

diff --git a/src/lib/ostream-buffer.c b/src/lib/ostream-buffer.c
index 1a0a16f95e..0beb20ae8f 100644
--- a/src/lib/ostream-buffer.c
+++ b/src/lib/ostream-buffer.c
@@ -54,11 +54,13 @@ o_stream_buffer_sendv(struct ostream_private *stream,
 }
 
 static size_t
-o_stream_buffer_get_buffer_used_size(const struct ostream_private *stream)
+o_stream_buffer_get_buffer_used_size(const struct ostream_private *stream ATTR_UNUSED)
 {
-	struct buffer_ostream *bstream = (struct buffer_ostream *)stream;
-
-	return bstream->buf->used;
+	/* Don't treat the destination buffer as the ostream buffer size.
+	   Otherwise ostream-buffer can't be used in a normal way in some
+	   places that stop sending more data to it if the buffer size grows
+	   beyond IO_BLOCK_SIZE. */
+	return 0;
 }
 
 struct ostream *o_stream_create_buffer(buffer_t *buf)
diff --git a/src/lib/test-ostream-buffer.c b/src/lib/test-ostream-buffer.c
index 42c792f63d..4df8d6a0d8 100644
--- a/src/lib/test-ostream-buffer.c
+++ b/src/lib/test-ostream-buffer.c
@@ -66,32 +66,34 @@ static void test_ostream_buffer_size(void)
 
 	test_begin("ostream buffer size/available");
 	output = o_stream_create_buffer(str);
-	test_assert(o_stream_get_buffer_used_size(output) == 0);
+	test_assert(str_len(str) == 0);
 	test_assert(o_stream_get_buffer_avail_size(output) == (size_t)-1);
 
 	/* test shrinking sink's max buffer size */
 	o_stream_set_max_buffer_size(output, 10);
-	test_assert(o_stream_get_buffer_used_size(output) == 0);
+	test_assert(str_len(str) == 0);
 	test_assert(o_stream_get_buffer_avail_size(output) == 10);
 
 	/* partial send */
 	const char *partial_input = "01234567890123456789";
 	ssize_t ret = o_stream_send_str(output, partial_input);
 	test_assert(ret == 10);
-	test_assert(o_stream_get_buffer_used_size(output) == 10);
-	test_assert(o_stream_get_buffer_avail_size(output) == 0);
+	test_assert(str_len(str) == 10);
+	test_assert(o_stream_get_buffer_avail_size(output) == 10);
 	
 	/* increase max buffer size so that it can hold the whole message */
 	o_stream_set_max_buffer_size(output, 100);
-	test_assert(o_stream_get_buffer_used_size(output) == 10);
-	test_assert(o_stream_get_buffer_avail_size(output) == 90);
+	test_assert(str_len(str) == 10);
+	test_assert(o_stream_get_buffer_avail_size(output) == 100);
 
 	/* send the rest */
 	ret += o_stream_send_str(output, partial_input + ret);
 	test_assert(ret == (ssize_t)strlen(partial_input));
 	test_assert(output->offset == str_len(str));
-	test_assert(o_stream_get_buffer_used_size(output) == 20);
-	test_assert(o_stream_get_buffer_avail_size(output) == 80);
+	test_assert(str_len(str) == 20);
+
+	/* used size is always 0 */
+	test_assert(o_stream_get_buffer_used_size(output) == 0);
 
 	/* check buffered data */
 	test_assert(strcmp(str_c(str), partial_input) == 0);