Add low-level plugin API.

src/common/Makefile.am

@@ -35,6 +35,7 @@ libcommon_la_SOURCES = 	\
 	pack.c		\
 	hostlist.c	\
 	parse_spec.c	\
+	plugin.c	\
 	read_config.c	\
 	slurm_errno.c	\
 	slurm_protocol_api.c	\
@@ -63,6 +64,7 @@ noinst_HEADERS = 	\
 	pack.h		\
 	hostlist.h	\
 	parse_spec.h	\
+	plugin.h	\
 	read_config.h	\
 	slurm_auth.h    \
 	slurm_protocol_api.h	\

src/common/plugin.c

+/*****************************************************************************\
+ * plugin.h - plugin architecture implementation.
+ *****************************************************************************
+ *  Copyright (C) 2002 The Regents of the University of California.
+ *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ *  Written by AUTHOR <AUTHOR@llnl.gov>.
+ *  UCRL-CODE-2002-040.
+ *  
+ *  This file is part of SLURM, a resource management program.
+ *  For details, see <http://www.llnl.gov/linux/slurm/>.
+ *  
+ *  SLURM is free software; you can redistribute it and/or modify it under
+ *  the terms of the GNU General Public License as published by the Free
+ *  Software Foundation; either version 2 of the License, or (at your option)
+ *  any later version.
+ *  
+ *  SLURM is distributed in the hope that it will be useful, but WITHOUT ANY
+ *  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ *  FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+ *  details.
+ *  
+ *  You should have received a copy of the GNU General Public License along
+ *  with SLURM; if not, write to the Free Software Foundation, Inc.,
+ *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
+\*****************************************************************************/
+
+#include <sys/types.h>
+#include <stdio.h>
+#include <assert.h>
+#include <dlfcn.h>
+
+#include "src/common/plugin.h"
+
+
+plugin_handle_t
+plugin_load_from_file( const char *fq_path )
+{
+	plugin_handle_t plug;
+
+	/* Try to open the shared object. */
+	plug = dlopen( fq_path, RTLD_LAZY );
+	if ( plug == NULL ) {
+		return NULL;
+	}
+
+	/* Now see if our required symbols are defined. */
+	if ( ( dlsym( plug, PLUGIN_NAME ) == NULL ) ||
+	     ( dlsym( plug, PLUGIN_TYPE ) == NULL ) ||
+	     ( dlsym( plug, PLUGIN_VERSION ) == NULL ) ) {
+		return NULL;
+	}
+
+	return plug;
+}
+
+
+void
+plugin_unload( plugin_handle_t plug )
+{
+	assert( plug );
+	(void) dlclose( plug );
+}
+
+
+void *
+plugin_get_sym( plugin_handle_t plug, const char *name )
+{
+	return dlsym( plug, name );
+}
+
+const char *
+plugin_get_name( plugin_handle_t plug )
+{
+	return (const char *) dlsym( plug, PLUGIN_NAME );
+}
+
+const char *
+plugin_get_type( plugin_handle_t plug )
+{
+	return (const char *) dlsym( plug, PLUGIN_TYPE );
+}
+
+uint32_t
+plugin_get_version( plugin_handle_t plug )
+{
+	uint32_t *ptr = (uint32_t *) dlsym( plug, PLUGIN_VERSION );
+	return ptr ? *ptr : 0;
+}
+
+int
+plugin_get_syms( plugin_handle_t plug,
+				 int n_syms,
+				 const char *names[],
+				 void *ptrs[] )
+{
+	int i, count;
+
+	count = 0;
+	for ( i = 0; i < n_syms; ++i ) {
+		ptrs[ i ] = dlsym( plug, names[ i ] );
+		if ( ptrs[ i ] ) ++count;
+	}
+
+	return count;
+}
+

src/common/plugin.h

+/*****************************************************************************\
+ * plugin.h - plugin abstraction and operations.
+ *****************************************************************************
+ *  Copyright (C) 2002 The Regents of the University of California.
+ *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ *  Written by AUTHOR <AUTHOR@llnl.gov>.
+ *  UCRL-CODE-2002-040.
+ *  
+ *  This file is part of SLURM, a resource management program.
+ *  For details, see <http://www.llnl.gov/linux/slurm/>.
+ *  
+ *  SLURM is free software; you can redistribute it and/or modify it under
+ *  the terms of the GNU General Public License as published by the Free
+ *  Software Foundation; either version 2 of the License, or (at your option)
+ *  any later version.
+ *  
+ *  SLURM is distributed in the hope that it will be useful, but WITHOUT ANY
+ *  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ *  FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+ *  details.
+ *  
+ *  You should have received a copy of the GNU General Public License along
+ *  with SLURM; if not, write to the Free Software Foundation, Inc.,
+ *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
+\*****************************************************************************/
+
+#ifndef __GENERIC_PLUGIN_H__
+#define __GENERIC_PLUGIN_H__
+
+#if HAVE_CONFIG_H
+#  include "config.h"
+#  if HAVE_INTTYPES_H
+#    include <inttypes.h>
+#  else
+#    if HAVE_STDINT_H
+#      include <stdint.h>
+#    endif
+#  endif /* HAVE_INTTYPES_H */
+#else /* ! HAVE_CONFIG_H_ */
+#  include <inttypes.h>
+#endif /* HAVE_CONFIG_H */
+
+#include "src/common/slurm_errno.h"
+
+/*
+ * These symbols are required to be defined in any plugin managed by
+ * this code.  Use these macros instead of string literals in order to
+ * avoid typographical errors.
+ *
+ * Their meanings are described in the sample plugin.
+ */
+#define PLUGIN_NAME		"plugin_name"
+#define PLUGIN_TYPE		"plugin_type"
+#define PLUGIN_VERSION		"plugin_version"
+
+/*
+ * Opaque type for plugin handle.  Most plugin operations will want
+ * of these.
+ *
+ * Currently there is no user-space memory associated with the plugin
+ * handle other than the pointer with which it is implemented.  While
+ * allowing a handle to pass out of scope without explicit destruction
+ * will not leak user memory, it may leave the plugin loaded in memory.
+ */
+typedef void *plugin_handle_t;
+
+#define PLUGIN_INVALID_HANDLE ((void*)0)
+
+/*
+ * Simplest way to get a plugin -- load it from a file.
+ *
+ * fq_path - the fully-qualified pathname (i.e., from root) to
+ * the plugin to load.
+ *
+ * Returns a handle if successful, or NULL if not.
+ *
+ * The plugin's initialization code will be executed prior
+ * to this function's return.
+ */
+plugin_handle_t plugin_load_from_file( const char *fq_path );
+
+/*
+ * Unload a plugin from memory.
+ */
+void plugin_unload( plugin_handle_t plug );
+
+/*
+ * Get the address of a named symbol in the plugin.
+ *
+ * Returns the address of the symbol or NULL if not found.
+ */
+void *plugin_get_sym( plugin_handle_t plug, const char *name );
+
+/*
+ * Access functions to get the name, type, and version of a plugin
+ * from the plugin itself.
+ */
+const char *plugin_get_name( plugin_handle_t plug );
+const char *plugin_get_type( plugin_handle_t plug );
+uint32_t plugin_get_version( plugin_handle_t plug );
+
+/*
+ * Get the addresses of several symbols from the plugin at once.
+ *
+ * n_syms - the number of symbols in names[].
+ * names[] - an argv-like array of symbol names to resolve.
+ * ptrs[] - an array of pointers into which the addresses of the respective
+ * 	symbols should be placed.  ptrs[i] will receive the address of
+ *	names[i].
+ *
+ * Returns the number of symbols successfully resolved.  Pointers whose
+ * associated symbol name was not found will be set to NULL.
+ */
+int plugin_get_syms( plugin_handle_t plug,
+		     int n_syms,
+		     const char *names[],
+		     void *ptrs[] );
+
+#endif /*__GENERIC_PLUGIN_H__*/