o update slurm_auth_init() to be MT-safe

src/common/slurm_auth.c

@@ -3,7 +3,7 @@
  *****************************************************************************
  *  Copyright (C) 2002 The Regents of the University of California.
  *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
- *  Written by Kevin Tew <tew1@llnl.gov> et. al.
+ *  Written by Jay Windley <jwindley@lnxi.com>
  *  UCRL-CODE-2002-040.
  *  
  *  This file is part of SLURM, a resource management program.
@@ -47,12 +47,12 @@
 typedef struct slurm_auth_ops {
 	void *	(*alloc)	( void );
 	void	(*free)		( void *cred );
-	int		(*activate)	( void *cred, int secs );
-	int		(*verify)	( void *cred );
+	int	(*activate)	( void *cred, int secs );
+	int	(*verify)	( void *cred );
 	uid_t	(*get_uid)	( void *cred );
 	gid_t	(*get_gid)	( void *cred );
 	void	(*pack)		( void *cred, Buf buf );
-	int		(*unpack)	( void *cred, Buf buf );
+	int	(*unpack)	( void *cred, Buf buf );
 	void	(*print)	( void *cred, FILE *fp );
 } slurm_auth_ops_t;
 
@@ -63,7 +63,7 @@ typedef struct slurm_auth_ops {
  * operations implemented pertinent to that context.
  *
  * auth_type - the string (presumably from configuration files)
- * describing the desired form of authentication, such as "auth/munged"
+ * describing the desired form of authentication, such as "auth/munge"
  * or "auth/kerberos" or "auth/none".
  *
  * plugin_list - the plugin rack managing the loading and unloading of
@@ -86,11 +86,13 @@ struct slurm_auth_context {
  * A global authentication context.  "Global" in the sense that there's
  * only one, with static bindings.  We don't export it.
  */
-static slurm_auth_context_t g_context = NULL;
+static slurm_auth_context_t g_context    = NULL;
+static pthread_mutex_t      context_lock = PTHREAD_MUTEX_INITIALIZER;
 
 static slurm_ctl_conf_t conf;
 static pthread_mutex_t config_lock = PTHREAD_MUTEX_INITIALIZER;
 
+
 static char *
 get_plugin_dir( void )
 {
@@ -228,23 +230,30 @@ slurm_auth_context_destroy( slurm_auth_context_t c )
 int
 slurm_auth_init( void )
 {
-	if ( g_context ) {
-		return SLURM_SUCCESS;
-	}
+	int retval = SLURM_SUCCESS;
+
+	slurm_mutex_lock( &context_lock );
 
+	if ( g_context ) 
+		goto done;
 	
 	g_context = slurm_auth_context_create( get_auth_type() );
 	if ( g_context == NULL ) {
 		verbose( "cannot create a context for %s", get_auth_type() );
-		return SLURM_ERROR;
+		retval = SLURM_ERROR;
+		goto done;
 	}
 	
 	if ( slurm_auth_get_ops( g_context ) == NULL ) {
 		verbose( "cannot resolve plugin operations" );
-		return SLURM_ERROR;
+		retval = SLURM_ERROR;
 	} else {
-		return SLURM_SUCCESS;
+		retval = SLURM_SUCCESS;
 	}
+
+    done:
+	slurm_mutex_unlock( &context_lock );
+	return retval;
 }
 
 /*
@@ -361,12 +370,8 @@ c_slurm_auth_print( slurm_auth_context_t c, void *cred, FILE *fp )
 void *
 g_slurm_auth_alloc( void )
 {
-	if ( ! g_context ) {
-		if ( slurm_auth_init() != SLURM_SUCCESS ) {
-			error( "can't allocate credential - authentication init failed" );
-			return NULL;
-		}
-	}
+	if ( slurm_auth_init() < 0 )
+		return NULL;
 
 	return (*(g_context->ops.alloc))();
 }
@@ -374,12 +379,8 @@ g_slurm_auth_alloc( void )
 void
 g_slurm_auth_free( void *cred )
 {
-	if ( ! g_context ) {
-		if ( slurm_auth_init() != SLURM_SUCCESS ) {
-			error( "can't free credential - authentication init failed" );
-			return;
-		}
-	}
+	if ( slurm_auth_init() < 0 )
+		return;
 
 	(*(g_context->ops.free))( cred );
 }
@@ -387,12 +388,8 @@ g_slurm_auth_free( void *cred )
 int
 g_slurm_auth_activate( void *cred, int secs )
 {
-	if ( ! g_context ) {
-		if ( slurm_auth_init() != SLURM_SUCCESS ) {
-			error( "can't activate credential - authentication init failed" );
-			return SLURM_ERROR;
-		}
-	}
+	if ( slurm_auth_init() < 0 )
+		return SLURM_ERROR;
 
 	return (*(g_context->ops.activate))( cred, secs );
 }
@@ -400,12 +397,8 @@ g_slurm_auth_activate( void *cred, int secs )
 int
 g_slurm_auth_verify( void *cred )
 {
-	if ( ! g_context ) {
-		if ( slurm_auth_init() != SLURM_SUCCESS ) {
-			error( "can't verify credential - authentication init failed" );
-			return SLURM_ERROR;
-		}
-	}
+	if ( slurm_auth_init() < 0 )
+		return SLURM_ERROR;
 	
 	return (*(g_context->ops.verify))( cred );
 }
@@ -413,12 +406,8 @@ g_slurm_auth_verify( void *cred )
 uid_t
 g_slurm_auth_get_uid( void *cred )
 {
-	if ( ! g_context ) {
-		if ( slurm_auth_init() != SLURM_SUCCESS ) {
-			error( "can't get UID - authentication init failed" );
-			return SLURM_AUTH_NOBODY;
-		}
-	}
+	if ( slurm_auth_init() < 0 )
+		return SLURM_AUTH_NOBODY;
 	
 	return (*(g_context->ops.get_uid))( cred );
 }
@@ -426,12 +415,8 @@ g_slurm_auth_get_uid( void *cred )
 gid_t
 g_slurm_auth_get_gid( void *cred )
 {
-	if ( ! g_context ) {
-		if ( slurm_auth_init() != SLURM_SUCCESS ) {
-			error( "can't get GID - authentication init failed" );
-			return SLURM_AUTH_NOBODY;
-		}
-	}
+	if ( slurm_auth_init() < 0 )
+		return SLURM_AUTH_NOBODY;
 	
 	return (*(g_context->ops.get_gid))( cred );
 }
@@ -439,12 +424,8 @@ g_slurm_auth_get_gid( void *cred )
 void
 g_slurm_auth_pack( void *cred, Buf buf )
 {
-	if ( ! g_context ) {
-		if ( slurm_auth_init() != SLURM_SUCCESS ) {
-			error( "can't pack credential - authentication init failed" );
-			return;
-		}
-	}
+	if ( slurm_auth_init() < 0 )
+		return;
 	
 	(*(g_context->ops.pack))( cred, buf );
 }
@@ -452,12 +433,8 @@ g_slurm_auth_pack( void *cred, Buf buf )
 int
 g_slurm_auth_unpack( void *cred, Buf buf )
 {
-	if ( ! g_context ) {
-		if ( slurm_auth_init() != SLURM_SUCCESS ) {
-			error( "can't unpack credential - authentication init failed" );
-			return SLURM_ERROR;
-		}
-	}
+	if ( slurm_auth_init() < 0 )
+		return SLURM_ERROR;
 	
 	return (*(g_context->ops.unpack))( cred, buf );
 }
@@ -465,12 +442,8 @@ g_slurm_auth_unpack( void *cred, Buf buf )
 void
 g_slurm_auth_print( void *cred, FILE *fp )
 {
-	if ( ! g_context ) {
-		if ( slurm_auth_init() != SLURM_SUCCESS ) {
-			error( "can't print credential - authentication init failed" );
-			return;
-		}
-	}
+	if ( slurm_auth_init() < 0 )
+		return;
 	
 	(*(g_context->ops.print))( cred, fp );
 }