From d9f9b3df1063b1a7c547484cec8dafc54da8c216 Mon Sep 17 00:00:00 2001
From: Max Kellermann <max@musicpd.org>
Date: Wed, 1 Jul 2020 15:03:24 +0200
Subject: [PATCH] input/file: detect premature end of file

A bug report (https://github.com/MusicPlayerDaemon/MPD/issues/912)
suggests that on Linux, reading on `cifs` files may rarely return 0 (=
end of file) before the end of the file has really been reached.  But
that's just a theory which I need to validate, so this runtime check
shall catch this condition before the assertion in
DecoderBridge::Read() crashes MPD.  Let's see.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/912
---
 NEWS                                  | 1 +
 src/input/plugins/FileInputPlugin.cxx | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/NEWS b/NEWS
index bd4caf30b..c43b3b4f8 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,7 @@ ver 0.21.25 (not yet released)
 * protocol:
   - fix crash when using "rangeid" while playing
 * input
+  - file: detect premature end of file
   - smbclient: don't send credentials to MPD clients
 
 ver 0.21.24 (2020/06/10)
diff --git a/src/input/plugins/FileInputPlugin.cxx b/src/input/plugins/FileInputPlugin.cxx
index 989d3de74..0a6f31438 100644
--- a/src/input/plugins/FileInputPlugin.cxx
+++ b/src/input/plugins/FileInputPlugin.cxx
@@ -26,6 +26,8 @@
 #include "system/FileDescriptor.hxx"
 #include "util/RuntimeError.hxx"
 
+#include <cinttypes> // for PRIu64 (PRIoffset)
+
 #include <sys/stat.h>
 #include <fcntl.h>
 
@@ -94,6 +96,11 @@ FileInputStream::Read(void *ptr, size_t read_size)
 		nbytes = reader.Read(ptr, read_size);
 	}
 
+	if (nbytes == 0 && !IsEOF())
+		throw FormatRuntimeError("Unexpected end of file %s"
+					 " at %" PRIoffset " of %" PRIoffset,
+					 GetURI(), GetOffset(), GetSize());
+
 	offset += nbytes;
 	return nbytes;
 }