diff -r 97f767832c52 -r 5701b7859a31 db.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/db.c	Wed Sep 14 16:49:28 2011 -0700
@@ -0,0 +1,146 @@
+/* vim: set noet nosta sw=4 ts=4 ft=c : */
+/*
+Copyright (c) 2011, Mahlon E. Smith <mahlon@martini.nu>
+All rights reserved.
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above copyright
+      notice, this list of conditions and the following disclaimer in the
+      documentation and/or other materials provided with the distribution.
+
+    * Neither the name of Mahlon E. Smith nor the names of his
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY
+EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE REGENTS AND CONTRIBUTORS BE LIABLE FOR ANY
+DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#include "volta.h"
+#include "db.h"
+
+const unsigned short int DB_VERSION = 1;
+
+
+/*
+ * Connect to the database specified in the 'v' global struct,
+ * and populate v.db with a handle to it.
+ *
+ * If required, automatically handle initializing/upgrading a DB.
+ *
+ */
+int
+db_attach( void )
+{
+	if ( v.db != NULL )          return( SQLITE_OK );    /* already attached */
+	if ( strlen(v.dbname) == 0 ) return( SQLITE_ERROR ); /* name not set */
+
+	debug( 2, LOC, "Attaching to database '%s'\n", v.dbname );
+	if ( sqlite3_open( v.dbname, &v.db ) != SQLITE_OK ) {
+		debug( 1, LOC, "Error when attaching to database: %s\n", sqlite3_errmsg(v.db) );
+		return( sqlite3_errcode(v.db) );
+	}
+
+	/* check DB version */
+	unsigned short int version = db_version();
+	if ( version != DB_VERSION ) {
+		debug( 1, LOC, "Database version mismatch: expected %hu, got %d.\n",
+				DB_VERSION, version );
+
+		/* We're in need of a DB initialization, or just behind.
+		 * Attempt to "stair step" upgrade to the current version. */
+		if ( version < DB_VERSION ) {
+			return( db_upgrade(version) );
+		}
+
+		/* Something else is wack. */
+		else {
+			return( SQLITE_ERROR );
+		}
+	}
+
+	return( SQLITE_OK );
+}
+
+
+/*
+ * Perform automatic stair-step upgrades of DB versions
+ * to get up to the current version expected from code.
+ *
+ */
+int
+db_upgrade( unsigned short int current_version )
+{
+	unsigned short int i = 0;
+	char user_pragma[30];
+	char sql_file[30];
+	char *upgrade_sql = NULL;
+
+	for ( i = current_version + 1; i <= DB_VERSION; i++ ) {
+		if ( i == 1 ) {
+			debug( 1, LOC, "Initializing new database.\n" );
+		}
+		else {
+			debug( 1, LOC, "Upgrading database version from %hu to %hu\n", current_version, i );
+		}
+
+		sprintf( sql_file, "sql/%d.sql", i );
+		upgrade_sql = slurp_file( sql_file );
+		if ( upgrade_sql == NULL ) return( SQLITE_ERROR );
+
+		/* If there is SQL to execute, do so and then reset for more */
+		if ( sqlite3_exec( v.db, upgrade_sql, NULL, NULL, NULL ) != SQLITE_OK ) {
+			debug( 1, LOC, "Error upgrading database: %s\n", sqlite3_errmsg(v.db) );
+			return( sqlite3_errcode(v.db) );
+		}
+		free( upgrade_sql );
+		upgrade_sql = NULL;
+
+		/* update version metadata in DB if update was successful */
+		current_version = i;
+		sprintf( user_pragma, "PRAGMA user_version = %hu;", current_version );
+		if ( sqlite3_exec( v.db, user_pragma, NULL, NULL, NULL ) != SQLITE_OK ) {
+			debug( 1, LOC, "Error upgrading database: %s\n", sqlite3_errmsg(v.db) );
+			return( sqlite3_errcode(v.db) );
+		}
+	}
+
+	return( SQLITE_OK );
+}
+
+
+/*
+ * Fetch and return the database's current version. or -1 on error.
+ * The database should already be attached before calling this function.
+ *
+ */
+short int
+db_version( void )
+{
+	struct sqlite3_stmt *stmt;
+	int version = -1;
+
+	if ( sqlite3_prepare_v2( v.db, "PRAGMA user_version", -1, &stmt, NULL ) != SQLITE_OK ) {
+		debug( 1, LOC, "Error finding DB version: %s\n", sqlite3_errmsg(v.db) );
+		return( -1 );
+	}
+
+	if ( sqlite3_step( stmt ) == SQLITE_ROW )
+		version = sqlite3_column_int( stmt, 0 );
+
+	sqlite3_finalize( stmt );
+	return version;
+}
+