Added multiple security tests to pgp keyring against disk full and exceeded quota.

- copy files to tmp before appending new keys, then rename back to original.
- always check for disk full before syncing keyrings
- use tmp file to sync keyring
- new RsDirUtil::fileExists() method
- check system for disk space in pgp directory
- added RsPGPDirectory() method to RsInit


git-svn-id: http://svn.code.sf.net/p/retroshare/code/trunk@6541 b45a01b8-16f6-495d-af2f-9b41ad6348cc

libretroshare/src/rsserver/rsinit.cc

@@ -609,7 +609,8 @@ int RsInit::InitRetroShare(int argcIgnored, char **argvIgnored, bool strictCheck
 
 	get_configinit(RsInitConfig::basedir, RsInitConfig::preferedId);
 
-	std::string pgp_dir = RsInitConfig::basedir + "/pgp" ;
+	std::string pgp_dir = RsPGPDirectory() ;
+
 	if(!RsDirUtil::checkCreateDirectory(pgp_dir))
 		throw std::runtime_error("Cannot create pgp directory " + pgp_dir) ;
 
@@ -719,7 +720,8 @@ bool RsInit::importIdentity(const std::string& fname,std::string& id,std::string
 
 bool RsInit::copyGnuPGKeyrings()
 {
-	std::string pgp_dir = RsInitConfig::basedir + "/pgp" ;
+	std::string pgp_dir = RsPGPDirectory() ;
+
 	if(!RsDirUtil::checkCreateDirectory(pgp_dir))
 		throw std::runtime_error("Cannot create pgp directory " + pgp_dir) ;
 
@@ -1720,6 +1722,10 @@ std::string RsInit::RsConfigDirectory()
 {
 	return RsInitConfig::basedir;
 }
+std::string RsInit::RsPGPDirectory()
+{
+	return RsInitConfig::basedir + "/pgp" ;
+}
 
 std::string RsInit::RsProfileConfigDirectory()
 {