hack to permit GetEnvironmentVariable usage without requiring getenv() conversion

	Windows has a major flaw when it comes to the use of getenv/putenv.
	getenv/putenv do not modify the actual environment of the process.
	Instead, they modify a copy of the environment block at the time the
	C Runtime Library was initialized for the current module.  In other 
	words, the C Runtime Library environment block for the executable
	is not the same as the C Runtime Library environment block for the
	krb5_32.dll library, etc.

	This results in problems when a process wants to set the default
	ccache name outside the krb5_context.  The krb5_context default ccname
	disappears when the context is destroyed.  gss_acquire_cred() suffers
	from the creation and destruction of krb5_contexts and therefore the
	krb5_context default ccname cannot be used to set a default ccname.
	Instead, the process environment must be used.

	In order to modify the process environment, SetEnvironmentVariable()
	must be used.  However, this does not result in the C Runtime Library
	environment blocks being updated.  putenv() does not see the definition
	of "KRB5CCNAME".  

	This patch modifies get_os_ccname() for Windows to check 
	GetEnvironmentVariable() before checking the registry.  This hack will
	work as long as there is no "KRB5CCNAME" variable in the C Runtime 
	Library environment block.  

	The long term solution is to replace all calls to getenv and putenv
	with GetEnvironmentVariable/SetEnvironmentVariable for Windows.

ticket: new
tags: pullup

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@19154 dc483132-0cff-0310-8789-dd5450dbe970

1 files changed, 9 insertions, 0 deletions

diff --git a/src/lib/krb5/os/ccdefname.c b/src/lib/krb5/os/ccdefname.c
index 4a9d184cd..e5059a5e6 100644
--- a/src/lib/krb5/os/ccdefname.c
+++ b/src/lib/krb5/os/ccdefname.c
@@ -148,6 +148,15 @@ static krb5_error_code get_from_os(char *name_buf, int name_size)
 	char *prefix = krb5_cc_dfl_ops->prefix;
         int size;
         char *p;
+        DWORD gle;
+
+	SetLastError(0);
+	GetEnvironmentVariable(KRB5_ENV_CCNAME, name_buf, name_size);
+	gle = GetLastError();
+	if (gle == 0)
+		return 0;
+	else if (gle != ERROR_ENVVAR_NOT_FOUND)
+		return ENOMEM;
 
 	if (get_from_registry(HKEY_CURRENT_USER,
                               name_buf, name_size) != 0)