From ae16d3efa83d43db583f04bdf7f98be4e3d763a4 Mon Sep 17 00:00:00 2001
From: Bogdan Marinescu <bogdan.marinescu@gmail.com>
Date: Thu, 5 Sep 2013 14:09:27 +0300
Subject: [PATCH] Fix NULL pointer indirection in FilePath

If the FileBase::lookup operation in the constructor of FilePath returns
NULL, subsequent operations (such as isFile()/isFileSystem()) will call
methods on a NULL 'fb' pointer. This commit fixes this issue by adding
explicit NULL checks and a new method in FilePath (exists()).
---
 libraries/mbed/api/FilePath.h      |  1 +
 libraries/mbed/common/FilePath.cpp | 11 ++++++++---
 libraries/mbed/common/retarget.cpp |  4 +++-
 3 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/libraries/mbed/api/FilePath.h b/libraries/mbed/api/FilePath.h
index 2e335bfeb6..3de1205048 100644
--- a/libraries/mbed/api/FilePath.h
+++ b/libraries/mbed/api/FilePath.h
@@ -34,6 +34,7 @@ public:
 
     bool    isFile(void);
     FileLike* file(void);
+    bool    exists(void);
 
 private:
     const char* file_name;
diff --git a/libraries/mbed/common/FilePath.cpp b/libraries/mbed/common/FilePath.cpp
index 7dbf710656..09147a2699 100644
--- a/libraries/mbed/common/FilePath.cpp
+++ b/libraries/mbed/common/FilePath.cpp
@@ -36,9 +36,6 @@ FilePath::FilePath(const char* file_path) : file_name(NULL), fb(NULL) {
         file_name++;
     }
 
-    FileBase::lookup(file_system, len);
-
-
     fb = FileBase::lookup(file_system, len);
 }
 
@@ -47,6 +44,8 @@ const char* FilePath::fileName(void) {
 }
 
 bool FilePath::isFileSystem(void) {
+    if (NULL == fb)
+        return false;
     return (fb->getPathType() == FileSystemPathType);
 }
 
@@ -58,6 +57,8 @@ FileSystemLike* FilePath::fileSystem(void) {
 }
 
 bool FilePath::isFile(void) {
+    if (NULL == fb)
+        return false;
     return (fb->getPathType() == FilePathType);
 }
 
@@ -68,4 +69,8 @@ FileLike* FilePath::file(void) {
     return NULL;
 }
 
+bool FilePath::exists(void) {
+    return fb != NULL;
+}
+
 } // namespace mbed
diff --git a/libraries/mbed/common/retarget.cpp b/libraries/mbed/common/retarget.cpp
index 987e5e4242..90a5dbe0e9 100644
--- a/libraries/mbed/common/retarget.cpp
+++ b/libraries/mbed/common/retarget.cpp
@@ -163,7 +163,9 @@ extern "C" FILEHANDLE PREFIX(_open)(const char* name, int openmode) {
     } else {
         FilePath path(name);
 
-        if (path.isFile()) {
+        if (!path.exists())
+            return -1;
+        else if (path.isFile()) {
             res = path.file();
         } else {
             FileSystemLike *fs = path.fileSystem();