postgres/contrib/pg_audit/pg_audit.c

/*------------------------------------------------------------------------------
 * pg_audit.c
 *
 * An audit logging extension for PostgreSQL. Provides detailed logging classes,
 * object level logging, and fully-qualified object names for all DML and DDL
 * statements where possible (See pgaudit.sgml for details).
 *
 * Copyright (c) 2014-2015, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *		  contrib/pg_audit/pg_audit.c
 *------------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/htup_details.h"
#include "access/sysattr.h"
#include "access/xact.h"
#include "catalog/catalog.h"
#include "catalog/objectaccess.h"
#include "catalog/pg_class.h"
#include "catalog/namespace.h"
#include "commands/dbcommands.h"
#include "catalog/pg_proc.h"
#include "commands/event_trigger.h"
#include "executor/executor.h"
#include "executor/spi.h"
#include "miscadmin.h"
#include "libpq/auth.h"
#include "nodes/nodes.h"
#include "tcop/utility.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/guc.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/rel.h"
#include "utils/syscache.h"
#include "utils/timestamp.h"

PG_MODULE_MAGIC;

void		_PG_init(void);

PG_FUNCTION_INFO_V1(pg_audit_ddl_command_end);
PG_FUNCTION_INFO_V1(pg_audit_sql_drop);

/*
 * Log Classes
 *
 * pgAudit categorizes actions into classes (eg: DDL, FUNCTION calls, READ
 * queries, WRITE queries).  A GUC is provided for the administrator to
 * configure which class (or classes) of actions to include in the
 * audit log.  We track the currently active set of classes using
 * auditLogBitmap.
 */

/* Bits within auditLogBitmap, defines the classes we understand */
#define LOG_DDL			(1 << 0)	/* CREATE/DROP/ALTER objects */
#define LOG_FUNCTION	(1 << 1)	/* Functions and DO blocks */
#define LOG_MISC		(1 << 2)	/* Statements not covered */
#define LOG_READ		(1 << 3)	/* SELECTs */
#define LOG_ROLE		(1 << 4)	/* GRANT/REVOKE, CREATE/ALTER/DROP ROLE */
#define LOG_WRITE		(1 << 5)	/* INSERT, UPDATE, DELETE, TRUNCATE */

#define LOG_NONE		0		/* nothing */
#define LOG_ALL			(0xFFFFFFFF)	/* All */

/* GUC variable for pg_audit.log, which defines the classes to log. */
char	   *auditLog = NULL;

/* Bitmap of classes selected */
static int	auditLogBitmap = LOG_NONE;

/*
 * String constants for log classes - used when processing tokens in the
 * pg_audit.log GUC.
 */
#define CLASS_DDL			"DDL"
#define CLASS_FUNCTION		"FUNCTION"
#define CLASS_MISC			"MISC"
#define CLASS_READ			"READ"
#define CLASS_ROLE			"ROLE"
#define CLASS_WRITE			"WRITE"

#define CLASS_NONE			"NONE"
#define CLASS_ALL			"ALL"

/*
 * GUC variable for pg_audit.log_catalog
 *
 * Administrators can choose to NOT log queries when all relations used in
 * the query are in pg_catalog.  Interactive sessions (eg: psql) can cause
 * a lot of noise in the logs which might be uninteresting.
 */
bool		auditLogCatalog = true;

/*
 * GUC variable for pg_audit.log_level
 *
 * Administrators can choose which log level the audit log is to be logged
 * at.  The default level is LOG, which goes into the server log but does
 * not go to the client.  Set to NOTICE in the regression tests.
 */
char	   *auditLogLevelString = NULL;
int			auditLogLevel = LOG;

/*
 * GUC variable for pg_audit.log_parameter
 *
 * Administrators can choose if parameters passed into a statement are
 * included in the audit log.
 */
bool		auditLogParameter = false;

/*
 * GUC variable for pg_audit.log_relation
 *
 * Administrators can choose, in SESSION logging, to log each relation involved
 * in READ/WRITE class queries.  By default, SESSION logs include the query but
 * do not have a log entry for each relation.
 */
bool		auditLogRelation = false;

/*
 * GUC variable for pg_audit.log_statement_once
 *
 * Administrators can choose to have the statement run logged only once instead
 * of on every line.  By default, the statement is repeated on every line of
 * the audit log to facilitate searching, but this can cause the log to be
 * unnecessairly bloated in some environments.
 */
bool		auditLogStatementOnce = false;

/*
 * GUC variable for pg_audit.role
 *
 * Administrators can choose which role to base OBJECT auditing off of.
 * Object-level auditing uses the privileges which are granted to this role to
 * determine if a statement should be logged.
 */
char	   *auditRole = NULL;

/*
 * String constants for the audit log fields.
 */

/*
 * Audit type, which is responsbile for the log message
 */
#define AUDIT_TYPE_OBJECT	"OBJECT"
#define AUDIT_TYPE_SESSION	"SESSION"

/*
 * Command, used for SELECT/DML and function calls.
 *
 * We hook into the executor, but we do not have access to the parsetree there.
 * Therefore we can't simply call CreateCommandTag() to get the command and have
 * to build it ourselves based on what information we do have.
 *
 * These should be updated if new commands are added to what the exectuor
 * currently handles.  Note that most of the interesting commands do not go
 * through the executor but rather ProcessUtility, where we have the parsetree.
 */
#define COMMAND_SELECT				"SELECT"
#define COMMAND_INSERT				"INSERT"
#define COMMAND_UPDATE				"UPDATE"
#define COMMAND_DELETE				"DELETE"
#define COMMAND_EXECUTE				"EXECUTE"
#define COMMAND_UNKNOWN				"UNKNOWN"

/*
 * Object type, used for SELECT/DML statements and function calls.
 *
 * For relation objects, this is essentially relkind (though we do not have
 * access to a function which will just return a string given a relkind;
 * getRelationTypeDescription() comes close but is not public currently).
 *
 * We also handle functions, so it isn't quite as simple as just relkind.
 *
 * This should be kept consistent with what is returned from
 * pg_event_trigger_ddl_commands(), as that's what we use for DDL.
 */
#define OBJECT_TYPE_TABLE			"TABLE"
#define OBJECT_TYPE_INDEX			"INDEX"
#define OBJECT_TYPE_SEQUENCE		"SEQUENCE"
#define OBJECT_TYPE_TOASTVALUE		"TOAST TABLE"
#define OBJECT_TYPE_VIEW			"VIEW"
#define OBJECT_TYPE_MATVIEW			"MATERIALIZED VIEW"
#define OBJECT_TYPE_COMPOSITE_TYPE	"COMPOSITE TYPE"
#define OBJECT_TYPE_FOREIGN_TABLE	"FOREIGN TABLE"
#define OBJECT_TYPE_FUNCTION		"FUNCTION"

#define OBJECT_TYPE_UNKNOWN			"UNKNOWN"

/*
 * String constants for testing role commands.  Rename and drop role statements
 * are assigned the nodeTag T_RenameStmt and T_DropStmt respectively.  This is
 * not very useful for classification, so we resort to comparing strings
 * against the result of CreateCommandTag(parsetree).
 */
#define COMMAND_ALTER_ROLE			"ALTER ROLE"
#define COMMAND_DROP_ROLE			"DROP ROLE"

/*
 * An AuditEvent represents an operation that potentially affects a single
 * object.  If a statement affects multiple objects then multiple AuditEvents
 * are created to represent them.
 */
typedef struct
{
	int64		statementId;	/* Simple counter */
	int64		substatementId; /* Simple counter */

	LogStmtLevel logStmtLevel;	/* From GetCommandLogLevel when possible,
								 * generated when not. */
	NodeTag		commandTag;		/* same here */
	const char *command;		/* same here */
	const char *objectType;		/* From event trigger when possible, generated
								 * when not. */
	char	   *objectName;		/* Fully qualified object identification */
	const char *commandText;	/* sourceText / queryString */
	ParamListInfo paramList;	/* QueryDesc/ProcessUtility parameters */

	bool		granted;		/* Audit role has object permissions? */
	bool		logged;			/* Track if we have logged this event, used
								 * post-ProcessUtility to make sure we log */
	bool		statementLogged;	/* Track if we have logged the statement */
} AuditEvent;

/*
 * A simple FIFO queue to keep track of the current stack of audit events.
 */
typedef struct AuditEventStackItem
{
	struct AuditEventStackItem *next;

	AuditEvent	auditEvent;

	int64		stackId;

	MemoryContext contextAudit;
	MemoryContextCallback contextCallback;
} AuditEventStackItem;

AuditEventStackItem *auditEventStack = NULL;

/*
 * pgAudit runs queries of its own when using the event trigger system.
 *
 * Track when we are running a query and don't log it.
 */
static bool internalStatement = false;

/*
 * Track running total for statements and substatements and whether or not
 * anything has been logged since the current statement began.
 */
static int64 statementTotal = 0;
static int64 substatementTotal = 0;
static int64 stackTotal = 0;

static bool statementLogged = false;

/*
 * Stack functions
 *
 * Audit events can go down to multiple levels so a stack is maintained to keep
 * track of them.
 */

/*
 * Respond to callbacks registered with MemoryContextRegisterResetCallback().
 * Removes the event(s) off the stack that have become obsolete once the
 * MemoryContext has been freed.  The callback should always be freeing the top
 * of the stack, but the code is tolerant of out-of-order callbacks.
 */
static void
stack_free(void *stackFree)
{
	AuditEventStackItem *nextItem = auditEventStack;

	/* Only process if the stack contains items */
	while (nextItem != NULL)
	{
		/* Check if this item matches the item to be freed */
		if (nextItem == (AuditEventStackItem *) stackFree)
		{
			/* Move top of stack to the item after the freed item */
			auditEventStack = nextItem->next;

			/* If the stack is not empty */
			if (auditEventStack == NULL)
			{
				/*
				 * Reset internal statement to false.  Normally this will be
				 * reset but in case of an error it might be left set.
				 */
				internalStatement = false;

				/*
				 * Reset sub statement total so the next statement will start
				 * from 1.
				 */
				substatementTotal = 0;

				/*
				 * Reset statement logged so that next statement will be
				 * logged.
				 */
				statementLogged = false;
			}

			return;
		}

		nextItem = nextItem->next;
	}
}

/*
 * Push a new audit event onto the stack and create a new memory context to
 * store it.
 */
static AuditEventStackItem *
stack_push()
{
	MemoryContext contextAudit;
	MemoryContext contextOld;
	AuditEventStackItem *stackItem;

	/*
	 * Create a new memory context to contain the stack item.  This will be
	 * free'd on stack_pop, or by our callback when the parent context is
	 * destroyed.
	 */
	contextAudit = AllocSetContextCreate(CurrentMemoryContext,
										 "pg_audit stack context",
										 ALLOCSET_DEFAULT_MINSIZE,
										 ALLOCSET_DEFAULT_INITSIZE,
										 ALLOCSET_DEFAULT_MAXSIZE);

	/* Save the old context to switch back to at the end */
	contextOld = MemoryContextSwitchTo(contextAudit);

	/* Create our new stack item in our context */
	stackItem = palloc0(sizeof(AuditEventStackItem));
	stackItem->contextAudit = contextAudit;
	stackItem->stackId = ++stackTotal;

	/*
	 * Setup a callback in case an error happens.  stack_free() will truncate
	 * the stack at this item.
	 */
	stackItem->contextCallback.func = stack_free;
	stackItem->contextCallback.arg = (void *) stackItem;
	MemoryContextRegisterResetCallback(contextAudit,
									   &stackItem->contextCallback);

	/* Push new item onto the stack */
	if (auditEventStack != NULL)
		stackItem->next = auditEventStack;
	else
		stackItem->next = NULL;

	auditEventStack = stackItem;

	MemoryContextSwitchTo(contextOld);

	return stackItem;
}

/*
 * Pop an audit event from the stack by deleting the memory context that
 * contains it.  The callback to stack_free() does the actual pop.
 */
static void
stack_pop(int64 stackId)
{
	/* Make sure what we want to delete is at the top of the stack */
	if (auditEventStack != NULL && auditEventStack->stackId == stackId)
		MemoryContextDelete(auditEventStack->contextAudit);
	else
		elog(ERROR, "pg_audit stack item " INT64_FORMAT " not found on top - cannot pop",
			 stackId);
}

/*
 * Check that an item is on the stack.  If not, an error will be raised since
 * this is a bad state to be in and it might mean audit records are being lost.
 */
static void
stack_valid(int64 stackId)
{
	AuditEventStackItem *nextItem = auditEventStack;

	/* Look through the stack for the stack entry */
	while (nextItem != NULL && nextItem->stackId != stackId)
		nextItem = nextItem->next;

	/* If we didn't find it, something went wrong. */
	if (nextItem == NULL)
		elog(ERROR, "pg_audit stack item " INT64_FORMAT " not found - top of stack is " INT64_FORMAT "",
			 stackId,
			 auditEventStack == NULL ? (int64) -1 : auditEventStack->stackId);
}

/*
 * Appends a properly quoted CSV field to StringInfo.
 */
static void
append_valid_csv(StringInfoData *buffer, const char *appendStr)
{
	const char *pChar;

	/*
	 * If the append string is null then do nothing.  NULL fields are not
	 * quoted in CSV.
	 */
	if (appendStr == NULL)
		return;

	/* Only format for CSV if appendStr contains: ", comma, \n, \r */
	if (strstr(appendStr, ",") || strstr(appendStr, "\"") ||
		strstr(appendStr, "\n") || strstr(appendStr, "\r"))
	{
		appendStringInfoCharMacro(buffer, '"');

		for (pChar = appendStr; *pChar; pChar++)
		{
			if (*pChar == '"')	/* double single quotes */
				appendStringInfoCharMacro(buffer, *pChar);

			appendStringInfoCharMacro(buffer, *pChar);
		}

		appendStringInfoCharMacro(buffer, '"');
	}
	/* Else just append */
	else
		appendStringInfoString(buffer, appendStr);
}

/*
 * Takes an AuditEvent, classifies it, then logs it if appropriate.
 *
 * Logging is decided based on if the statement is in one of the classes being
 * logged or if an object used has been marked for auditing.
 *
 * Objects are marked for auditing by the auditor role being granted access
 * to the object.  The kind of access (INSERT, UPDATE, etc) is also considered
 * and logging is only performed when the kind of access matches the granted
 * right on the object.
 *
 * This will need to be updated if new kinds of GRANTs are added.
 */
static void
log_audit_event(AuditEventStackItem *stackItem)
{
	/* By default, put everything in the MISC class. */
	int			class = LOG_MISC;
	const char *className = CLASS_MISC;
	MemoryContext contextOld;
	StringInfoData auditStr;


	/* Classify the statement using log stmt level and the command tag */
	switch (stackItem->auditEvent.logStmtLevel)
	{
			/* All mods go in WRITE class, except EXECUTE */
		case LOGSTMT_MOD:
			className = CLASS_WRITE;
			class = LOG_WRITE;

			switch (stackItem->auditEvent.commandTag)
			{
					/* Currently, only EXECUTE is different */
				case T_ExecuteStmt:
					className = CLASS_MISC;
					class = LOG_MISC;
					break;
				default:
					break;
			}
			break;

			/* These are DDL, unless they are ROLE */
		case LOGSTMT_DDL:
			className = CLASS_DDL;
			class = LOG_DDL;

			/* Identify role statements */
			switch (stackItem->auditEvent.commandTag)
			{
					/* We know these are all role statements */
				case T_GrantStmt:
				case T_GrantRoleStmt:
				case T_CreateRoleStmt:
				case T_DropRoleStmt:
				case T_AlterRoleStmt:
				case T_AlterRoleSetStmt:
					className = CLASS_ROLE;
					class = LOG_ROLE;
					break;

					/*
					 * Rename and Drop are general and therefore we have to do
					 * an additional check against the command string to see
					 * if they are role or regular DDL.
					 */
				case T_RenameStmt:
				case T_DropStmt:
					if (pg_strcasecmp(stackItem->auditEvent.command,
									  COMMAND_ALTER_ROLE) == 0 ||
						pg_strcasecmp(stackItem->auditEvent.command,
									  COMMAND_DROP_ROLE) == 0)
					{
						className = CLASS_ROLE;
						class = LOG_ROLE;
					}
					break;

				default:
					break;
			}
			break;

			/* Classify the rest */
		case LOGSTMT_ALL:
			switch (stackItem->auditEvent.commandTag)
			{
					/* READ statements */
				case T_CopyStmt:
				case T_SelectStmt:
				case T_PrepareStmt:
				case T_PlannedStmt:
					className = CLASS_READ;
					class = LOG_READ;
					break;

					/* FUNCTION statements */
				case T_DoStmt:
					className = CLASS_FUNCTION;
					class = LOG_FUNCTION;
					break;

				default:
					break;
			}
			break;

		case LOGSTMT_NONE:
			break;
	}

	/*----------
	 * Only log the statement if:
	 *
	 * 1. If object was selected for audit logging (granted), or
	 * 2. The statement belongs to a class that is being logged
	 *
	 * If neither of these is true, return.
	 *----------
	 */
	if (!stackItem->auditEvent.granted && !(auditLogBitmap & class))
		return;

	/*
	 * Use audit memory context in case something is not free'd while
	 * appending strings and parameters.
	 */
	contextOld = MemoryContextSwitchTo(stackItem->contextAudit);

	/* Set statement and substatement IDs */
	if (stackItem->auditEvent.statementId == 0)
	{
		/* If nothing has been logged yet then create a new statement Id */
		if (!statementLogged)
		{
			statementTotal++;
			statementLogged = true;
		}

		stackItem->auditEvent.statementId = statementTotal;
		stackItem->auditEvent.substatementId = ++substatementTotal;
	}

	/*
	 * Create the audit substring
	 *
	 * The type-of-audit-log and statement/substatement ID are handled below,
	 * this string is everything else.
	 */
	initStringInfo(&auditStr);
	append_valid_csv(&auditStr, stackItem->auditEvent.command);

	appendStringInfoCharMacro(&auditStr, ',');
	append_valid_csv(&auditStr, stackItem->auditEvent.objectType);

	appendStringInfoCharMacro(&auditStr, ',');
	append_valid_csv(&auditStr, stackItem->auditEvent.objectName);

	/*
	 * If auditLogStatmentOnce is true, then only log the statement and
	 * parameters if they have not already been logged for this substatement.
	 */
	appendStringInfoCharMacro(&auditStr, ',');
	if (!stackItem->auditEvent.statementLogged || !auditLogStatementOnce)
	{
		append_valid_csv(&auditStr, stackItem->auditEvent.commandText);

		appendStringInfoCharMacro(&auditStr, ',');

		/* Handle parameter logging, if enabled. */
		if (auditLogParameter)
		{
			int			paramIdx;
			int			numParams;
			StringInfoData paramStrResult;
			ParamListInfo paramList = stackItem->auditEvent.paramList;

			numParams = paramList == NULL ? 0 : paramList->numParams;

			/* Create the param substring */
			initStringInfo(&paramStrResult);

			/* Iterate through all params */
			for (paramIdx = 0; paramList != NULL && paramIdx < numParams;
				 paramIdx++)
			{
				ParamExternData *prm = &paramList->params[paramIdx];
				Oid			typeOutput;
				bool		typeIsVarLena;
				char	   *paramStr;

				/* Add a comma for each param */
				if (paramIdx != 0)
					appendStringInfoCharMacro(&paramStrResult, ',');

				/* Skip if null or if oid is invalid */
				if (prm->isnull || !OidIsValid(prm->ptype))
					continue;

				/* Output the string */
				getTypeOutputInfo(prm->ptype, &typeOutput, &typeIsVarLena);
				paramStr = OidOutputFunctionCall(typeOutput, prm->value);

				append_valid_csv(&paramStrResult, paramStr);
				pfree(paramStr);
			}

			if (numParams == 0)
				appendStringInfoString(&auditStr, "<none>");
			else
				append_valid_csv(&auditStr, paramStrResult.data);
		}
		else
			appendStringInfoString(&auditStr, "<not logged>");

		stackItem->auditEvent.statementLogged = true;
	}
	else
		/* we were asked to not log it */
		appendStringInfoString(&auditStr,
							   "<previously logged>,<previously logged>");

	/*
	 * Log the audit entry.  Note: use of INT64_FORMAT here is bad for
	 * translatability, but we currently haven't got translation support in
	 * pg_audit anyway.
	 */
	ereport(auditLogLevel,
			(errmsg("AUDIT: %s," INT64_FORMAT "," INT64_FORMAT ",%s,%s",
					stackItem->auditEvent.granted ?
					AUDIT_TYPE_OBJECT : AUDIT_TYPE_SESSION,
					stackItem->auditEvent.statementId,
					stackItem->auditEvent.substatementId,
					className,
					auditStr.data)));

	stackItem->auditEvent.logged = true;

	MemoryContextSwitchTo(contextOld);
}

/*
 * Check if the role or any inherited role has any permission in the mask.  The
 * public role is excluded from this check and superuser permissions are not
 * considered.
 */
static bool
audit_on_acl(Datum aclDatum,
			 Oid auditOid,
			 AclMode mask)
{
	bool		result = false;
	Acl		   *acl;
	AclItem    *aclItemData;
	int			aclIndex;
	int			aclTotal;

	/* Detoast column's ACL if necessary */
	acl = DatumGetAclP(aclDatum);

	/* Get the acl list and total number of items */
	aclTotal = ACL_NUM(acl);
	aclItemData = ACL_DAT(acl);

	/* Check privileges granted directly to auditOid */
	for (aclIndex = 0; aclIndex < aclTotal; aclIndex++)
	{
		AclItem    *aclItem = &aclItemData[aclIndex];

		if (aclItem->ai_grantee == auditOid &&
			aclItem->ai_privs & mask)
		{
			result = true;
			break;
		}
	}

	/*
	 * Check privileges granted indirectly via role memberships. We do this in
	 * a separate pass to minimize expensive indirect membership tests.  In
	 * particular, it's worth testing whether a given ACL entry grants any
	 * privileges still of interest before we perform the has_privs_of_role
	 * test.
	 */
	if (!result)
	{
		for (aclIndex = 0; aclIndex < aclTotal; aclIndex++)
		{
			AclItem    *aclItem = &aclItemData[aclIndex];

			/* Don't test public or auditOid (it has been tested already) */
			if (aclItem->ai_grantee == ACL_ID_PUBLIC ||
				aclItem->ai_grantee == auditOid)
				continue;

			/*
			 * Check that the role has the required privileges and that it is
			 * inherited by auditOid.
			 */
			if (aclItem->ai_privs & mask &&
				has_privs_of_role(auditOid, aclItem->ai_grantee))
			{
				result = true;
				break;
			}
		}
	}

	/* if we have a detoasted copy, free it */
	if (acl && (Pointer) acl != DatumGetPointer(aclDatum))
		pfree(acl);

	return result;
}

/*
 * Check if a role has any of the permissions in the mask on a relation.
 */
static bool
audit_on_relation(Oid relOid,
				  Oid auditOid,
				  AclMode mask)
{
	bool		result = false;
	HeapTuple	tuple;
	Datum		aclDatum;
	bool		isNull;

	/* Get relation tuple from pg_class */
	tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relOid));
	if (!HeapTupleIsValid(tuple))
		return false;

	/* Get the relation's ACL */
	aclDatum = SysCacheGetAttr(RELOID, tuple, Anum_pg_class_relacl,
							   &isNull);

	/* Only check if non-NULL, since NULL means no permissions */
	if (!isNull)
		result = audit_on_acl(aclDatum, auditOid, mask);

	/* Free the relation tuple */
	ReleaseSysCache(tuple);

	return result;
}

/*
 * Check if a role has any of the permissions in the mask on a column.
 */
static bool
audit_on_attribute(Oid relOid,
				   AttrNumber attNum,
				   Oid auditOid,
				   AclMode mask)
{
	bool		result = false;
	HeapTuple	attTuple;
	Datum		aclDatum;
	bool		isNull;

	/* Get the attribute's ACL */
	attTuple = SearchSysCache2(ATTNUM,
							   ObjectIdGetDatum(relOid),
							   Int16GetDatum(attNum));
	if (!HeapTupleIsValid(attTuple))
		return false;

	/* Only consider attributes that have not been dropped */
	if (!((Form_pg_attribute) GETSTRUCT(attTuple))->attisdropped)
	{
		aclDatum = SysCacheGetAttr(ATTNUM, attTuple, Anum_pg_attribute_attacl,
								   &isNull);

		if (!isNull)
			result = audit_on_acl(aclDatum, auditOid, mask);
	}

	/* Free attribute */
	ReleaseSysCache(attTuple);

	return result;
}

/*
 * Check if a role has any of the permissions in the mask on a column in
 * the provided set.  If the set is empty, then all valid columns in the
 * relation will be tested.
 */
static bool
audit_on_any_attribute(Oid relOid,
					   Oid auditOid,
					   Bitmapset *attributeSet,
					   AclMode mode)
{
	bool		result = false;
	AttrNumber	col;
	Bitmapset  *tmpSet;

	/* If bms is empty then check for any column match */
	if (bms_is_empty(attributeSet))
	{
		HeapTuple	classTuple;
		AttrNumber	nattrs;
		AttrNumber	curr_att;

		/* Get relation to determine total columns */
		classTuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relOid));

		if (!HeapTupleIsValid(classTuple))
			return false;

		nattrs = ((Form_pg_class) GETSTRUCT(classTuple))->relnatts;
		ReleaseSysCache(classTuple);

		/* Check each column */
		for (curr_att = 1; curr_att <= nattrs; curr_att++)
			if (audit_on_attribute(relOid, curr_att, auditOid, mode))
				return true;
	}

	/* bms_first_member is destructive, so make a copy before using it. */
	tmpSet = bms_copy(attributeSet);

	/* Check each column */
	while ((col = bms_first_member(tmpSet)) >= 0)
	{
		col += FirstLowInvalidHeapAttributeNumber;

		if (col != InvalidAttrNumber &&
			audit_on_attribute(relOid, col, auditOid, mode))
		{
			result = true;
			break;
		}
	}

	bms_free(tmpSet);

	return result;
}

/*
 * Create AuditEvents for SELECT/DML operations via executor permissions checks.
 */
static void
log_select_dml(Oid auditOid, List *rangeTabls)
{
	ListCell   *lr;
	bool		first = true;
	bool		found = false;

	/* Do not log if this is an internal statement */
	if (internalStatement)
		return;

	foreach(lr, rangeTabls)
	{
		Oid			relOid;
		Relation	rel;
		RangeTblEntry *rte = lfirst(lr);

		/* We only care about tables, and can ignore subqueries etc. */
		if (rte->rtekind != RTE_RELATION)
			continue;

		found = true;

		/*
		 * If we are not logging all-catalog queries (auditLogCatalog is
		 * false) then filter out any system relations here.
		 */
		relOid = rte->relid;
		rel = relation_open(relOid, NoLock);

		if (!auditLogCatalog && IsSystemNamespace(RelationGetNamespace(rel)))
		{
			relation_close(rel, NoLock);
			continue;
		}

		/*
		 * Default is that this was not through a grant, to support session
		 * logging.  Will be updated below if a grant is found.
		 */
		auditEventStack->auditEvent.granted = false;

		/*
		 * If this is the first RTE then session log unless auditLogRelation
		 * is set.
		 */
		if (first && !auditLogRelation)
		{
			log_audit_event(auditEventStack);

			first = false;
		}

		/*
		 * We don't have access to the parsetree here, so we have to generate
		 * the node type, object type, and command tag by decoding
		 * rte->requiredPerms and rte->relkind.
		 */
		if (rte->requiredPerms & ACL_INSERT)
		{
			auditEventStack->auditEvent.logStmtLevel = LOGSTMT_MOD;
			auditEventStack->auditEvent.commandTag = T_InsertStmt;
			auditEventStack->auditEvent.command = COMMAND_INSERT;
		}
		else if (rte->requiredPerms & ACL_UPDATE)
		{
			auditEventStack->auditEvent.logStmtLevel = LOGSTMT_MOD;
			auditEventStack->auditEvent.commandTag = T_UpdateStmt;
			auditEventStack->auditEvent.command = COMMAND_UPDATE;
		}
		else if (rte->requiredPerms & ACL_DELETE)
		{
			auditEventStack->auditEvent.logStmtLevel = LOGSTMT_MOD;
			auditEventStack->auditEvent.commandTag = T_DeleteStmt;
			auditEventStack->auditEvent.command = COMMAND_DELETE;
		}
		else if (rte->requiredPerms & ACL_SELECT)
		{
			auditEventStack->auditEvent.logStmtLevel = LOGSTMT_ALL;
			auditEventStack->auditEvent.commandTag = T_SelectStmt;
			auditEventStack->auditEvent.command = COMMAND_SELECT;
		}
		else
		{
			auditEventStack->auditEvent.logStmtLevel = LOGSTMT_ALL;
			auditEventStack->auditEvent.commandTag = T_Invalid;
			auditEventStack->auditEvent.command = COMMAND_UNKNOWN;
		}

		/* Use the relation type to assign object type */
		switch (rte->relkind)
		{
			case RELKIND_RELATION:
				auditEventStack->auditEvent.objectType = OBJECT_TYPE_TABLE;
				break;

			case RELKIND_INDEX:
				auditEventStack->auditEvent.objectType = OBJECT_TYPE_INDEX;
				break;

			case RELKIND_SEQUENCE:
				auditEventStack->auditEvent.objectType = OBJECT_TYPE_SEQUENCE;
				break;

			case RELKIND_TOASTVALUE:
				auditEventStack->auditEvent.objectType = OBJECT_TYPE_TOASTVALUE;
				break;

			case RELKIND_VIEW:
				auditEventStack->auditEvent.objectType = OBJECT_TYPE_VIEW;
				break;

			case RELKIND_COMPOSITE_TYPE:
				auditEventStack->auditEvent.objectType = OBJECT_TYPE_COMPOSITE_TYPE;
				break;

			case RELKIND_FOREIGN_TABLE:
				auditEventStack->auditEvent.objectType = OBJECT_TYPE_FOREIGN_TABLE;
				break;

			case RELKIND_MATVIEW:
				auditEventStack->auditEvent.objectType = OBJECT_TYPE_MATVIEW;
				break;

			default:
				auditEventStack->auditEvent.objectType = OBJECT_TYPE_UNKNOWN;
				break;
		}

		/* Get a copy of the relation name and assign it to object name */
		auditEventStack->auditEvent.objectName =
			quote_qualified_identifier(get_namespace_name(
												  RelationGetNamespace(rel)),
									   RelationGetRelationName(rel));
		relation_close(rel, NoLock);

		/* Perform object auditing only if the audit role is valid */
		if (auditOid != InvalidOid)
		{
			AclMode		auditPerms = (ACL_SELECT | ACL_UPDATE | ACL_INSERT | ACL_DELETE) & rte->requiredPerms;

			/*
			 * If any of the required permissions for the relation are granted
			 * to the audit role then audit the relation
			 */
			if (audit_on_relation(relOid, auditOid, auditPerms))
				auditEventStack->auditEvent.granted = true;

			/*
			 * Else check if the audit role has column-level permissions for
			 * select, insert, or update.
			 */
			else if (auditPerms != 0)
			{
				/*
				 * Check the select columns
				 */
				if (auditPerms & ACL_SELECT)
					auditEventStack->auditEvent.granted =
						audit_on_any_attribute(relOid, auditOid,
											   rte->selectedCols,
											   ACL_SELECT);

				/*
				 * Check the insert columns
				 */
				if (!auditEventStack->auditEvent.granted &&
					auditPerms & ACL_INSERT)
					auditEventStack->auditEvent.granted =
						audit_on_any_attribute(relOid, auditOid,
											   rte->insertedCols,
											   auditPerms);

				/*
				 * Check the update columns
				 */
				if (!auditEventStack->auditEvent.granted &&
					auditPerms & ACL_UPDATE)
					auditEventStack->auditEvent.granted =
						audit_on_any_attribute(relOid, auditOid,
											   rte->updatedCols,
											   auditPerms);
			}
		}

		/* Do relation level logging if a grant was found */
		if (auditEventStack->auditEvent.granted)
		{
			auditEventStack->auditEvent.logged = false;
			log_audit_event(auditEventStack);
		}

		/* Do relation level logging if auditLogRelation is set */
		if (auditLogRelation)
		{
			auditEventStack->auditEvent.logged = false;
			auditEventStack->auditEvent.granted = false;
			log_audit_event(auditEventStack);
		}

		pfree(auditEventStack->auditEvent.objectName);
	}

	/*
	 * If no tables were found that means that RangeTbls was empty or all
	 * relations were in the system schema.  In that case still log a session
	 * record.
	 */
	if (!found)
	{
		auditEventStack->auditEvent.granted = false;
		auditEventStack->auditEvent.logged = false;

		log_audit_event(auditEventStack);
	}
}

/*
 * Create AuditEvents for non-catalog function execution, as detected by
 * log_object_access() below.
 */
static void
log_function_execute(Oid objectId)
{
	HeapTuple	proctup;
	Form_pg_proc proc;
	AuditEventStackItem *stackItem;

	/* Get info about the function. */
	proctup = SearchSysCache1(PROCOID, ObjectIdGetDatum(objectId));

	if (!proctup)
		elog(ERROR, "cache lookup failed for function %u", objectId);

	proc = (Form_pg_proc) GETSTRUCT(proctup);

	/*
	 * Logging execution of all pg_catalog functions would make the log
	 * unusably noisy.
	 */
	if (IsSystemNamespace(proc->pronamespace))
	{
		ReleaseSysCache(proctup);
		return;
	}

	/* Push audit event onto the stack */
	stackItem = stack_push();

	/* Generate the fully-qualified function name. */
	stackItem->auditEvent.objectName =
		quote_qualified_identifier(get_namespace_name(proc->pronamespace),
								   NameStr(proc->proname));
	ReleaseSysCache(proctup);

	/* Log the function call */
	stackItem->auditEvent.logStmtLevel = LOGSTMT_ALL;
	stackItem->auditEvent.commandTag = T_DoStmt;
	stackItem->auditEvent.command = COMMAND_EXECUTE;
	stackItem->auditEvent.objectType = OBJECT_TYPE_FUNCTION;
	stackItem->auditEvent.commandText = stackItem->next->auditEvent.commandText;

	log_audit_event(stackItem);

	/* Pop audit event from the stack */
	stack_pop(stackItem->stackId);
}

/*
 * Hook functions
 */
static ExecutorCheckPerms_hook_type next_ExecutorCheckPerms_hook = NULL;
static ProcessUtility_hook_type next_ProcessUtility_hook = NULL;
static object_access_hook_type next_object_access_hook = NULL;
static ExecutorStart_hook_type next_ExecutorStart_hook = NULL;

/*
 * Hook ExecutorStart to get the query text and basic command type for queries
 * that do not contain a table and so can't be idenitified accurately in
 * ExecutorCheckPerms.
 */
static void
pg_audit_ExecutorStart_hook(QueryDesc *queryDesc, int eflags)
{
	AuditEventStackItem *stackItem = NULL;

	if (!internalStatement)
	{
		/* Push the audit even onto the stack */
		stackItem = stack_push();

		/* Initialize command using queryDesc->operation */
		switch (queryDesc->operation)
		{
			case CMD_SELECT:
				stackItem->auditEvent.logStmtLevel = LOGSTMT_ALL;
				stackItem->auditEvent.commandTag = T_SelectStmt;
				stackItem->auditEvent.command = COMMAND_SELECT;
				break;

			case CMD_INSERT:
				stackItem->auditEvent.logStmtLevel = LOGSTMT_MOD;
				stackItem->auditEvent.commandTag = T_InsertStmt;
				stackItem->auditEvent.command = COMMAND_INSERT;
				break;

			case CMD_UPDATE:
				stackItem->auditEvent.logStmtLevel = LOGSTMT_MOD;
				stackItem->auditEvent.commandTag = T_UpdateStmt;
				stackItem->auditEvent.command = COMMAND_UPDATE;
				break;

			case CMD_DELETE:
				stackItem->auditEvent.logStmtLevel = LOGSTMT_MOD;
				stackItem->auditEvent.commandTag = T_DeleteStmt;
				stackItem->auditEvent.command = COMMAND_DELETE;
				break;

			default:
				stackItem->auditEvent.logStmtLevel = LOGSTMT_ALL;
				stackItem->auditEvent.commandTag = T_Invalid;
				stackItem->auditEvent.command = COMMAND_UNKNOWN;
				break;
		}

		/* Initialize the audit event */
		stackItem->auditEvent.commandText = queryDesc->sourceText;
		stackItem->auditEvent.paramList = queryDesc->params;
	}

	/* Call the previous hook or standard function */
	if (next_ExecutorStart_hook)
		next_ExecutorStart_hook(queryDesc, eflags);
	else
		standard_ExecutorStart(queryDesc, eflags);

	/*
	 * Move the stack memory context to the query memory context.  This needs
	 * to be done here because the query context does not exist before the
	 * call to standard_ExecutorStart() but the stack item is required by
	 * pg_audit_ExecutorCheckPerms_hook() which is called during
	 * standard_ExecutorStart().
	 */
	if (stackItem)
		MemoryContextSetParent(stackItem->contextAudit,
							   queryDesc->estate->es_query_cxt);
}

/*
 * Hook ExecutorCheckPerms to do session and object auditing for DML.
 */
static bool
pg_audit_ExecutorCheckPerms_hook(List *rangeTabls, bool abort)
{
	Oid			auditOid;

	/* Get the audit oid if the role exists */
	auditOid = get_role_oid(auditRole, true);

	/* Log DML if the audit role is valid or session logging is enabled */
	if ((auditOid != InvalidOid || auditLogBitmap != 0) &&
		!IsAbortedTransactionBlockState())
		log_select_dml(auditOid, rangeTabls);

	/* Call the next hook function */
	if (next_ExecutorCheckPerms_hook &&
		!(*next_ExecutorCheckPerms_hook) (rangeTabls, abort))
		return false;

	return true;
}

/*
 * Hook ProcessUtility to do session auditing for DDL and utility commands.
 */
static void
pg_audit_ProcessUtility_hook(Node *parsetree,
							 const char *queryString,
							 ProcessUtilityContext context,
							 ParamListInfo params,
							 DestReceiver *dest,
							 char *completionTag)
{
	AuditEventStackItem *stackItem = NULL;
	int64		stackId = 0;

	/*
	 * Don't audit substatements.  All the substatements we care about should
	 * be covered by the event triggers.
	 */
	if (context <= PROCESS_UTILITY_QUERY && !IsAbortedTransactionBlockState())
	{
		/* Process top level utility statement */
		if (context == PROCESS_UTILITY_TOPLEVEL)
		{
			if (auditEventStack != NULL)
				elog(ERROR, "pg_audit stack is not empty");

			stackItem = stack_push();
			stackItem->auditEvent.paramList = params;
		}
		else
			stackItem = stack_push();

		stackId = stackItem->stackId;
		stackItem->auditEvent.logStmtLevel = GetCommandLogLevel(parsetree);
		stackItem->auditEvent.commandTag = nodeTag(parsetree);
		stackItem->auditEvent.command = CreateCommandTag(parsetree);
		stackItem->auditEvent.commandText = queryString;

		/*
		 * If this is a DO block log it before calling the next ProcessUtility
		 * hook.
		 */
		if (auditLogBitmap & LOG_FUNCTION &&
			stackItem->auditEvent.commandTag == T_DoStmt &&
			!IsAbortedTransactionBlockState())
			log_audit_event(stackItem);
	}

	/* Call the standard process utility chain. */
	if (next_ProcessUtility_hook)
		(*next_ProcessUtility_hook) (parsetree, queryString, context,
									 params, dest, completionTag);
	else
		standard_ProcessUtility(parsetree, queryString, context,
								params, dest, completionTag);

	/*
	 * Process the audit event if there is one.  Also check that this event
	 * was not popped off the stack by a memory context being free'd
	 * elsewhere.
	 */
	if (stackItem && !IsAbortedTransactionBlockState())
	{
		/*
		 * Make sure the item we want to log is still on the stack - if not
		 * then something has gone wrong and an error will be raised.
		 */
		stack_valid(stackId);

		/*
		 * Log the utility command if logging is on, the command has not
		 * already been logged by another hook, and the transaction is not
		 * aborted.
		 */
		if (auditLogBitmap != 0 && !stackItem->auditEvent.logged)
			log_audit_event(stackItem);
	}
}

/*
 * Hook object_access_hook to provide fully-qualified object names for function
 * calls.
 */
static void
pg_audit_object_access_hook(ObjectAccessType access,
							Oid classId,
							Oid objectId,
							int subId,
							void *arg)
{
	if (auditLogBitmap & LOG_FUNCTION && access == OAT_FUNCTION_EXECUTE &&
		auditEventStack && !IsAbortedTransactionBlockState())
		log_function_execute(objectId);

	if (next_object_access_hook)
		(*next_object_access_hook) (access, classId, objectId, subId, arg);
}

/*
 * Event trigger functions
 */

/*
 * Supply additional data for (non drop) statements that have event trigger
 * support and can be deparsed.
 *
 * Drop statements are handled below through the older sql_drop event trigger.
 */
Datum
pg_audit_ddl_command_end(PG_FUNCTION_ARGS)
{
	EventTriggerData *eventData;
	int			result,
				row;
	TupleDesc	spiTupDesc;
	const char *query;
	MemoryContext contextQuery;
	MemoryContext contextOld;

	/* Continue only if session DDL logging is enabled */
	if (~auditLogBitmap & LOG_DDL)
		PG_RETURN_NULL();

	/* Be sure the module was loaded */
	if (!auditEventStack)
		elog(ERROR, "pg_audit not loaded before call to "
			 "pg_audit_ddl_command_end()");

	/* This is an internal statement - do not log it */
	internalStatement = true;

	/* Make sure the fuction was fired as a trigger */
	if (!CALLED_AS_EVENT_TRIGGER(fcinfo))
		elog(ERROR, "not fired by event trigger manager");

	/* Switch memory context for query */
	contextQuery = AllocSetContextCreate(
										 CurrentMemoryContext,
						   "pg_audit_func_ddl_command_end temporary context",
										 ALLOCSET_DEFAULT_MINSIZE,
										 ALLOCSET_DEFAULT_INITSIZE,
										 ALLOCSET_DEFAULT_MAXSIZE);
	contextOld = MemoryContextSwitchTo(contextQuery);

	/* Get information about triggered events */
	eventData = (EventTriggerData *) fcinfo->context;

	auditEventStack->auditEvent.logStmtLevel =
		GetCommandLogLevel(eventData->parsetree);
	auditEventStack->auditEvent.commandTag =
		nodeTag(eventData->parsetree);
	auditEventStack->auditEvent.command =
		CreateCommandTag(eventData->parsetree);

	/* Return objects affected by the (non drop) DDL statement */
	query = "SELECT UPPER(object_type), object_identity\n"
		"  FROM pg_event_trigger_ddl_commands()";

	/* Attempt to connect */
	result = SPI_connect();
	if (result < 0)
		elog(ERROR, "pg_audit_ddl_command_end: SPI_connect returned %d",
			 result);

	/* Execute the query */
	result = SPI_execute(query, true, 0);
	if (result != SPI_OK_SELECT)
		elog(ERROR, "pg_audit_ddl_command_end: SPI_execute returned %d",
			 result);

	/* Iterate returned rows */
	spiTupDesc = SPI_tuptable->tupdesc;
	for (row = 0; row < SPI_processed; row++)
	{
		HeapTuple	spiTuple;

		spiTuple = SPI_tuptable->vals[row];

		/* Supply object name and type for audit event */
		auditEventStack->auditEvent.objectType =
			SPI_getvalue(spiTuple, spiTupDesc, 1);
		auditEventStack->auditEvent.objectName =
			SPI_getvalue(spiTuple, spiTupDesc, 2);

		/* Log the audit event */
		log_audit_event(auditEventStack);
	}

	/* Complete the query */
	SPI_finish();

	MemoryContextSwitchTo(contextOld);
	MemoryContextDelete(contextQuery);

	/* No longer in an internal statement */
	internalStatement = false;

	PG_RETURN_NULL();
}

/*
 * Supply additional data for drop statements that have event trigger support.
 */
Datum
pg_audit_sql_drop(PG_FUNCTION_ARGS)
{
	int			result,
				row;
	TupleDesc	spiTupDesc;
	const char *query;
	MemoryContext contextQuery;
	MemoryContext contextOld;

	if (~auditLogBitmap & LOG_DDL)
		PG_RETURN_NULL();

	/* Be sure the module was loaded */
	if (!auditEventStack)
		elog(ERROR, "pg_audit not loaded before call to "
			 "pg_audit_sql_drop()");

	/* This is an internal statement - do not log it */
	internalStatement = true;

	/* Make sure the fuction was fired as a trigger */
	if (!CALLED_AS_EVENT_TRIGGER(fcinfo))
		elog(ERROR, "not fired by event trigger manager");

	/* Switch memory context for the query */
	contextQuery = AllocSetContextCreate(
										 CurrentMemoryContext,
						   "pg_audit_func_ddl_command_end temporary context",
										 ALLOCSET_DEFAULT_MINSIZE,
										 ALLOCSET_DEFAULT_INITSIZE,
										 ALLOCSET_DEFAULT_MAXSIZE);
	contextOld = MemoryContextSwitchTo(contextQuery);

	/* Return objects affected by the drop statement */
	query = "SELECT UPPER(object_type),\n"
		"       object_identity\n"
		"  FROM pg_event_trigger_dropped_objects()\n"
		" WHERE lower(object_type) <> 'type'\n"
		"   AND schema_name <> 'pg_toast'";

	/* Attempt to connect */
	result = SPI_connect();
	if (result < 0)
		elog(ERROR, "pg_audit_ddl_drop: SPI_connect returned %d",
			 result);

	/* Execute the query */
	result = SPI_execute(query, true, 0);
	if (result != SPI_OK_SELECT)
		elog(ERROR, "pg_audit_ddl_drop: SPI_execute returned %d",
			 result);

	/* Iterate returned rows */
	spiTupDesc = SPI_tuptable->tupdesc;
	for (row = 0; row < SPI_processed; row++)
	{
		HeapTuple	spiTuple;

		spiTuple = SPI_tuptable->vals[row];

		auditEventStack->auditEvent.objectType =
			SPI_getvalue(spiTuple, spiTupDesc, 1);
		auditEventStack->auditEvent.objectName =
			SPI_getvalue(spiTuple, spiTupDesc, 2);

		log_audit_event(auditEventStack);
	}

	/* Complete the query */
	SPI_finish();

	MemoryContextSwitchTo(contextOld);
	MemoryContextDelete(contextQuery);

	/* No longer in an internal statement */
	internalStatement = false;

	PG_RETURN_NULL();
}

/*
 * GUC check and assign functions
 */

/*
 * Take a pg_audit.log value such as "read, write, dml", verify that each of the
 * comma-separated tokens corresponds to a LogClass value, and convert them into
 * a bitmap that log_audit_event can check.
 */
static bool
check_pg_audit_log(char **newVal, void **extra, GucSource source)
{
	List	   *flagRawList;
	char	   *rawVal;
	ListCell   *lt;
	int		   *flags;

	/* Make sure newval is a comma-separated list of tokens. */
	rawVal = pstrdup(*newVal);
	if (!SplitIdentifierString(rawVal, ',', &flagRawList))
	{
		GUC_check_errdetail("List syntax is invalid");
		list_free(flagRawList);
		pfree(rawVal);
		return false;
	}

	/*
	 * Check that we recognise each token, and add it to the bitmap we're
	 * building up in a newly-allocated int *f.
	 */
	if (!(flags = (int *) malloc(sizeof(int))))
		return false;

	*flags = 0;

	foreach(lt, flagRawList)
	{
		char	   *token = (char *) lfirst(lt);
		bool		subtract = false;
		int			class;

		/* If token is preceded by -, then the token is subtractive */
		if (token[0] == '-')
		{
			token++;
			subtract = true;
		}

		/* Test each token */
		if (pg_strcasecmp(token, CLASS_NONE) == 0)
			class = LOG_NONE;
		else if (pg_strcasecmp(token, CLASS_ALL) == 0)
			class = LOG_ALL;
		else if (pg_strcasecmp(token, CLASS_DDL) == 0)
			class = LOG_DDL;
		else if (pg_strcasecmp(token, CLASS_FUNCTION) == 0)
			class = LOG_FUNCTION;
		else if (pg_strcasecmp(token, CLASS_MISC) == 0)
			class = LOG_MISC;
		else if (pg_strcasecmp(token, CLASS_READ) == 0)
			class = LOG_READ;
		else if (pg_strcasecmp(token, CLASS_ROLE) == 0)
			class = LOG_ROLE;
		else if (pg_strcasecmp(token, CLASS_WRITE) == 0)
			class = LOG_WRITE;
		else
		{
			free(flags);
			pfree(rawVal);
			list_free(flagRawList);
			return false;
		}

		/* Add or subtract class bits from the log bitmap */
		if (subtract)
			*flags &= ~class;
		else
			*flags |= class;
	}

	pfree(rawVal);
	list_free(flagRawList);

	/* Store the bitmap for assign_pg_audit_log */
	*extra = flags;

	return true;
}

/*
 * Set pg_audit_log from extra (ignoring newVal, which has already been
 * converted to a bitmap above). Note that extra may not be set if the
 * assignment is to be suppressed.
 */
static void
assign_pg_audit_log(const char *newVal, void *extra)
{
	if (extra)
		auditLogBitmap = *(int *) extra;
}

/*
 * Take a pg_audit.log_level value such as "debug" and check that is is valid.
 * Return the enum value so it does not have to be checked again in the assign
 * function.
 */
static bool
check_pg_audit_log_level(char **newVal, void **extra, GucSource source)
{
	int		   *logLevel;

	/* Allocate memory to store the log level */
	if (!(logLevel = (int *) malloc(sizeof(int))))
		return false;

	/* Find the log level enum */
	if (pg_strcasecmp(*newVal, "debug") == 0)
		*logLevel = DEBUG2;
	else if (pg_strcasecmp(*newVal, "debug5") == 0)
		*logLevel = DEBUG5;
	else if (pg_strcasecmp(*newVal, "debug4") == 0)
		*logLevel = DEBUG4;
	else if (pg_strcasecmp(*newVal, "debug3") == 0)
		*logLevel = DEBUG3;
	else if (pg_strcasecmp(*newVal, "debug2") == 0)
		*logLevel = DEBUG2;
	else if (pg_strcasecmp(*newVal, "debug1") == 0)
		*logLevel = DEBUG1;
	else if (pg_strcasecmp(*newVal, "info") == 0)
		*logLevel = INFO;
	else if (pg_strcasecmp(*newVal, "notice") == 0)
		*logLevel = NOTICE;
	else if (pg_strcasecmp(*newVal, "warning") == 0)
		*logLevel = WARNING;
	else if (pg_strcasecmp(*newVal, "error") == 0)
		*logLevel = ERROR;
	else if (pg_strcasecmp(*newVal, "log") == 0)
		*logLevel = LOG;
	else if (pg_strcasecmp(*newVal, "fatal") == 0)
		*logLevel = FATAL;
	else if (pg_strcasecmp(*newVal, "panic") == 0)
		*logLevel = PANIC;

	/* Error if the log level enum is not found */
	else
	{
		free(logLevel);
		return false;
	}

	/* Return the log level enum */
	*extra = logLevel;

	return true;
}

/*
 * Set pg_audit_log from extra (ignoring newVal, which has already been
 * converted to an enum above). Note that extra may not be set if the
 * assignment is to be suppressed.
 */
static void
assign_pg_audit_log_level(const char *newVal, void *extra)
{
	if (extra)
		auditLogLevel = *(int *) extra;
}

/*
 * Define GUC variables and install hooks upon module load.
 */
void
_PG_init(void)
{
	/* Define pg_audit.log */
	DefineCustomStringVariable(
							   "pg_audit.log",

	 "Specifies which classes of statements will be logged by session audit "
		 "logging. Multiple classes can be provided using a comma-separated "
		  "list and classes can be subtracted by prefacing the class with a "
							   "- sign.",

							   NULL,
							   &auditLog,
							   "none",
							   PGC_SUSET,
							   GUC_LIST_INPUT | GUC_NOT_IN_SAMPLE,
							   check_pg_audit_log,
							   assign_pg_audit_log,
							   NULL);

	/* Define pg_audit.log_catalog */
	DefineCustomBoolVariable(
							 "pg_audit.log_catalog",

		"Specifies that session logging should be enabled in the case where "
		   "all relations in a statement are in pg_catalog.  Disabling this "
	 "setting will reduce noise in the log from tools like psql and PgAdmin "
							 "that query the catalog heavily.",

							 NULL,
							 &auditLogCatalog,
							 true,
							 PGC_SUSET,
							 GUC_NOT_IN_SAMPLE,
							 NULL, NULL, NULL);

	/* Define pg_audit.log_level */
	DefineCustomStringVariable(
							   "pg_audit.log_level",

		   "Specifies the log level that will be used for log entries. This "
	  "setting is used for regression testing and may also be useful to end "
	   "users for testing or other purposes.  It is not intended to be used "
	 "in a production environment as it may leak which statements are being "
							   "logged to the user.",

							   NULL,
							   &auditLogLevelString,
							   "log",
							   PGC_SUSET,
							   GUC_LIST_INPUT | GUC_NOT_IN_SAMPLE,
							   check_pg_audit_log_level,
							   assign_pg_audit_log_level,
							   NULL);

	/* Define pg_audit.log_parameter */
	DefineCustomBoolVariable(
							 "pg_audit.log_parameter",

	  "Specifies that audit logging should include the parameters that were "
	   "passed with the statement. When parameters are present they will be "
					   "be included in CSV format after the statement text.",

							 NULL,
							 &auditLogParameter,
							 false,
							 PGC_SUSET,
							 GUC_NOT_IN_SAMPLE,
							 NULL, NULL, NULL);

	/* Define pg_audit.log_relation */
	DefineCustomBoolVariable(
							 "pg_audit.log_relation",

	  "Specifies whether session audit logging should create a separate log "
		  "entry for each relation referenced in a SELECT or DML statement. "
	 "This is a useful shortcut for exhaustive logging without using object "
							 "audit logging.",

							 NULL,
							 &auditLogRelation,
							 false,
							 PGC_SUSET,
							 GUC_NOT_IN_SAMPLE,
							 NULL, NULL, NULL);

	/* Define pg_audit.log_statement_once */
	DefineCustomBoolVariable(
							 "pg_audit.log_statement_once",

			 "Specifies whether logging will include the statement text and "
		  "parameters with the first log entry for a statement/substatement "
	  "combination or with every entry.  Disabling this setting will result "
	   "in less verbose logging but may make it more difficult to determine "
					  "the statement that generated a log entry, though the "
	  "statement/substatement pair along with the process id should suffice "
			  "to identify the statement text logged with a previous entry.",

							 NULL,
							 &auditLogStatementOnce,
							 false,
							 PGC_SUSET,
							 GUC_NOT_IN_SAMPLE,
							 NULL, NULL, NULL);

	/* Define pg_audit.role */
	DefineCustomStringVariable(
							   "pg_audit.role",

	   "Specifies the master role to use for object audit logging.  Muliple "
	  "audit roles can be defined by granting them to the master role. This "
	  "allows multiple groups to be in charge of different aspects of audit "
							   "logging.",

							   NULL,
							   &auditRole,
							   "",
							   PGC_SUSET,
							   GUC_NOT_IN_SAMPLE,
							   NULL, NULL, NULL);

	/*
	 * Install our hook functions after saving the existing pointers to
	 * preserve the chains.
	 */
	next_ExecutorStart_hook = ExecutorStart_hook;
	ExecutorStart_hook = pg_audit_ExecutorStart_hook;

	next_ExecutorCheckPerms_hook = ExecutorCheckPerms_hook;
	ExecutorCheckPerms_hook = pg_audit_ExecutorCheckPerms_hook;

	next_ProcessUtility_hook = ProcessUtility_hook;
	ProcessUtility_hook = pg_audit_ProcessUtility_hook;

	next_object_access_hook = object_access_hook;
	object_access_hook = pg_audit_object_access_hook;
}