From 619fb92a081c4182a836f58153801daa396d5c6b Mon Sep 17 00:00:00 2001
From: Timo Sirainen <timo.sirainen@dovecot.fi>
Date: Fri, 8 Jun 2018 23:17:04 +0300
Subject: [PATCH] lib: istream-try - Don't assert-crash with empty parent
 istream

Fixes:
Panic: file istream.c: line 327 (i_stream_read_memarea): assertion failed: (stream->eof)
---
 src/lib/istream-try.c      |  5 +++++
 src/lib/test-istream-try.c | 26 +++++++++++++++++++++++++-
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/src/lib/istream-try.c b/src/lib/istream-try.c
index b033b776e3..df94a48669 100644
--- a/src/lib/istream-try.c
+++ b/src/lib/istream-try.c
@@ -76,6 +76,11 @@ static int i_stream_try_detect(struct try_istream *tstream)
 		}
 		if (ret == 0)
 			return 0;
+		if (try_input->stream_errno == 0) {
+			/* empty file */
+			tstream->istream.istream.eof = TRUE;
+			return -1;
+		}
 		if (try_input->stream_errno != EINVAL) {
 			tstream->istream.istream.stream_errno =
 				try_input->stream_errno;
diff --git a/src/lib/test-istream-try.c b/src/lib/test-istream-try.c
index 39a4185e73..91ac37ddd1 100644
--- a/src/lib/test-istream-try.c
+++ b/src/lib/test-istream-try.c
@@ -4,7 +4,7 @@
 #include "istream.h"
 #include "istream-try.h"
 
-void test_istream_try(void)
+static void test_istream_try_normal(void)
 {
 	bool finished = FALSE;
 
@@ -128,3 +128,27 @@ void test_istream_try(void)
 	i_assert(finished);
 	test_end();
 }
+
+static void test_istream_try_empty(void)
+{
+	test_begin("istream try empty stream");
+	struct istream *test_inputs[] = {
+		test_istream_create(""),
+		test_istream_create(""),
+		NULL
+	};
+	struct istream *try_input = istream_try_create(test_inputs);
+	test_assert(i_stream_read(try_input) == -1);
+	test_assert(try_input->eof);
+	test_assert(try_input->stream_errno == 0);
+	i_stream_unref(&test_inputs[0]);
+	i_stream_unref(&test_inputs[1]);
+	i_stream_unref(&try_input);
+	test_end();
+}
+
+void test_istream_try(void)
+{
+	test_istream_try_normal();
+	test_istream_try_empty();
+}
-- 
2.47.3