From 549f77eafe1d2e5592e655c8247de7afc07984b3 Mon Sep 17 00:00:00 2001
From: Emery Hemingway <emery@vfemail.net>
Date: Mon, 23 Nov 2015 13:39:29 +0100
Subject: [PATCH] Catch exceptions when creating VFS

Catch exceptions at File_system_factory::create.
Print error message in Dir_file_system.

Fixes #1786
---
 repos/os/include/vfs/dir_file_system.h      | 15 ++++++++++++---
 repos/os/src/lib/vfs/file_system_factory.cc | 21 +++++++++++++--------
 2 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/repos/os/include/vfs/dir_file_system.h b/repos/os/include/vfs/dir_file_system.h
index 7dc0194b72..c9a427c6d3 100644
--- a/repos/os/include/vfs/dir_file_system.h
+++ b/repos/os/include/vfs/dir_file_system.h
@@ -210,6 +210,8 @@ class Vfs::Dir_file_system : public File_system
 		:
 			_first_file_system(0)
 		{
+			using namespace Genode;
+
 			/* remember directory name */
 			if (node.has_type("fstab") || node.has_type("vfs"))
 				_name[0] = 0;
@@ -233,9 +235,16 @@ class Vfs::Dir_file_system : public File_system
 					continue;
 				}
 
-				char type_name[64];
-				sub_node.type_name(type_name, sizeof(type_name));
-				PWRN("unknown fstab node type <%s>", type_name);
+				PERR("failed to create <%s> VFS node", sub_node.type().string());
+				try {
+					String<64> value;
+					for (unsigned i = 0; i < 16; ++i) {
+						Xml_attribute attr = sub_node.attribute(i);
+						attr.value(&value);
+
+						PERR("\t%s=\"%s\"", attr.name().string(), value.string());
+					}
+				} catch (Xml_node::Nonexistent_attribute) { }
 			}
 		}
 
diff --git a/repos/os/src/lib/vfs/file_system_factory.cc b/repos/os/src/lib/vfs/file_system_factory.cc
index 746c065c8a..b07e5ec0c2 100644
--- a/repos/os/src/lib/vfs/file_system_factory.cc
+++ b/repos/os/src/lib/vfs/file_system_factory.cc
@@ -169,16 +169,21 @@ class Default_file_system_factory : public Vfs::Global_file_system_factory
 
 		Vfs::File_system *create(Genode::Xml_node node) override
 		{
-			/* try if type is handled by the currently registered fs types */
-			if (Vfs::File_system *fs = _try_create(node))
-				return fs;
-
-			/* probe for file system implementation available as shared lib */
-			if (_probe_external_factory(node)) {
-				/* try again with the new file system type loaded */
+			try {
+				/* try if type is handled by the currently registered fs types */
 				if (Vfs::File_system *fs = _try_create(node))
 					return fs;
-			}
+				/* if the builtin fails, do not try loading an external */
+			} catch (...) { return 0; }
+
+			try {
+				/* probe for file system implementation available as shared lib */
+				if (_probe_external_factory(node)) {
+					/* try again with the new file system type loaded */
+					if (Vfs::File_system *fs = _try_create(node))
+						return fs;
+				}
+			} catch (...) { }
 
 			return 0;
 		}