r=warren, 15457. Added file extension attribute to URL implementations

mailnews/base/util/nsMsgMailNewsUrl.cpp

@@ -332,6 +332,11 @@ NS_IMETHODIMP nsMsgMailNewsUrl::GetFileName(char * *aFileName)
 	return m_baseURL->GetFileName(aFileName);
 }
 
+NS_IMETHODIMP nsMsgMailNewsUrl::GetFileExtension(char * *aFileExtension)
+{
+    return NS_ERROR_NOT_IMPLEMENTED;
+}
+
 NS_IMETHODIMP nsMsgMailNewsUrl::SetFileName(const char * aFileName)
 {
 	return m_baseURL->SetFileName(aFileName);

netwerk/base/public/nsIURL.idl

@@ -52,6 +52,12 @@ interface nsIURL : nsIURI
      */
     attribute string FileName;
 
+    /**
+     * Returns the file extension portion of a filename in a url.
+     * If a file extension does not exist, the empty string is returned.
+     */
+    readonly attribute string FileExtension;
+
 	/**
 	 * Returns the parameters specified after the ; in the URL. 
 	 *

netwerk/base/src/nsStdURL.h

@@ -129,6 +129,26 @@ nsStdURL::GetFileName(char* *o_FileName)
     return DupString(o_FileName, mFileName);
 }
 
+inline NS_METHOD
+nsStdURL::GetFileExtension(char* *o_FileExtension)
+{
+    if (!o_FileExtension)
+        return NS_ERROR_NULL_POINTER;
+
+    char *dot = mFileName;
+    if (dot) {
+        while (*dot && (*dot != '.')) dot++; // goto the dot.
+        if (*dot) {
+            nsCAutoString ext(dot+1);
+            *o_FileExtension = ext.ToNewCString();
+            if (!*o_FileExtension) return NS_ERROR_OUT_OF_MEMORY;
+        } else {
+            *o_FileExtension = nsnull;
+        }
+    }
+    return NS_OK;
+}
+
 inline NS_METHOD
 nsStdURL::GetRef(char* *o_Ref)
 {