From 122ee0a0017b69dd7dc3e5296a1bf5c9985a1190 Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Wed, 13 May 2009 19:46:16 +0000
Subject: [PATCH] Added ReaderWriter::fileExists() method to help enable
 querrying of existing of files on servers using the curl plugin

---
 include/osgDB/Options      | 2 +-
 include/osgDB/ReaderWriter | 4 ++++
 src/osgDB/ReaderWriter.cpp | 9 +++++++++
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/include/osgDB/Options b/include/osgDB/Options
index febb7db72..38aa72acb 100644
--- a/include/osgDB/Options
+++ b/include/osgDB/Options
@@ -142,7 +142,7 @@ class OSGDB_EXPORT Options : public osg::Object
         void setPluginStringData(const std::string& s, const std::string& v) const { _pluginStringData[s] = v; }
 
         /** Get a string from the PluginStrData */
-        std::string getPluginStringData(const std::string& s) { return _pluginStringData[s]; }
+        std::string& getPluginStringData(const std::string& s) { return _pluginStringData[s]; }
 
         /** Get a value from the PluginData */
         const std::string getPluginStringData(const std::string& s) const
diff --git a/include/osgDB/ReaderWriter b/include/osgDB/ReaderWriter
index ee2d7fb1c..8eaa757eb 100644
--- a/include/osgDB/ReaderWriter
+++ b/include/osgDB/ReaderWriter
@@ -200,6 +200,10 @@ class OSGDB_EXPORT ReaderWriter : public osg::Object
 
         typedef osgDB::Options Options;
 
+        /** determine if a file exists, normally the default implementation will be approrpiate for local file access
+         *  but with plugins like the libcurl based on it will return true if the file is accessible a server.*/
+        virtual bool fileExists(const std::string& filename, const Options* options) const;
+
         /** open an archive for reading, writing, or to create an empty archive for writing to.*/ 
         virtual ReadResult openArchive(const std::string& /*fileName*/,ArchiveStatus, unsigned int =4096, const Options* =NULL) const { return ReadResult(ReadResult::NOT_IMPLEMENTED); }
 
diff --git a/src/osgDB/ReaderWriter.cpp b/src/osgDB/ReaderWriter.cpp
index 8fc2d029f..8cf48cf17 100644
--- a/src/osgDB/ReaderWriter.cpp
+++ b/src/osgDB/ReaderWriter.cpp
@@ -117,3 +117,12 @@ ReaderWriter::FeatureList ReaderWriter::featureAsString(ReaderWriter::Features f
     }
     return result;
 }
+
+bool ReaderWriter::fileExists(const std::string& filename, const Options* /*options*/) const
+{
+#ifdef OSG_USE_UTF8_FILENAME
+    return _waccess( OSGDB_STRING_TO_FILENAME(filename).c_str(), F_OK ) == 0;
+#else
+    return access( filename.c_str(), F_OK ) == 0;
+#endif
+}