plpgsql_debugger.c

/**********************************************************************
 * plpgsql_debugger.c	- Debugger for the PL/pgSQL procedural language
 *
 * Copyright (c) 2004-2018 EnterpriseDB Corporation. All Rights Reserved.
 *
 * Licensed under the Artistic License v2.0, see
 *		https://opensource.org/licenses/artistic-license-2.0
 * for full details
 *
 **********************************************************************/

#include "postgres.h"

#include <stdio.h>
#include <stdarg.h>
#include <unistd.h>
#include <errno.h>
#include <setjmp.h>
#include <signal.h>

#include "lib/stringinfo.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "globalbp.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/syscache.h"
#include "miscadmin.h"

#if INCLUDE_PACKAGE_SUPPORT
#include "spl.h"
#include "catalog/edb_variable.h"
#else
#include "plpgsql.h"
#endif

#include "pldebugger.h"

/* Include header for GETSTRUCT */
#if (PG_VERSION_NUM >= 90300)
#include "access/htup_details.h"
#endif

/*
 * We use a var_value structure to record  a little extra information about
 * each variable.
 */

typedef struct
{
	bool	    isnull;			/* TRUE -> this variable IS NULL */
	bool		visible;		/* hidden or visible? see is_visible_datum() */
	bool		duplicate_name;	/* Is this one of many vars with same name? */
} var_value;

/*
 * When the debugger decides that it needs to step through (or into) a
 * particular function invocation, it allocates a dbg_ctx and records the
 * address of that structure in the executor's context structure
 * (estate->plugin_info).
 *
 * The dbg_ctx keeps track of all of the information we need to step through
 * code and display variable values
 */

typedef struct
{
	PLpgSQL_function *	func;		/* Function definition */
	bool				stepping;	/* If TRUE, stop at next statement */
	var_value	     *  symbols;	/* Extra debugger-private info about variables */
	char			 ** argNames;	/* Argument names */
	int					argNameCount; /* Number of names pointed to by argNames */
	void 			 (* error_callback)(void *arg);
	void 			 (* assign_expr)( PLpgSQL_execstate *estate, PLpgSQL_datum *target, PLpgSQL_expr *expr );
#if INCLUDE_PACKAGE_SUPPORT
	PLpgSQL_package   * package;
#endif
} dbg_ctx;

static void 		 dbg_startup( PLpgSQL_execstate * estate, PLpgSQL_function * func );
static void 		 dbg_newstmt( PLpgSQL_execstate * estate, PLpgSQL_stmt * stmt );
static void 		 initialize_plugin_info( PLpgSQL_execstate * estate, PLpgSQL_function * func );

static char       ** fetchArgNames( PLpgSQL_function * func, int * nameCount );
static PLpgSQL_var * find_var_by_name( const PLpgSQL_execstate * estate, const char * var_name, int lineno, int * index );

static bool 		 is_datum_visible( PLpgSQL_datum * datum );
static bool			 is_var_visible( PLpgSQL_execstate * frame, int var_no );
static bool			 datumIsNull(PLpgSQL_datum *datum);
static bool          varIsArgument(const PLpgSQL_execstate *estate, PLpgSQL_function *func, int varNo, char **p_argname);
static char		   * get_text_val( PLpgSQL_var * var, char ** name, char ** type );

#if INCLUDE_PACKAGE_SUPPORT
static const char * plugin_name  = "spl_plugin";
#else
static const char * plugin_name  = "PLpgSQL_plugin";
#endif

static PLpgSQL_plugin plugin_funcs = { dbg_startup, NULL, NULL, dbg_newstmt, NULL };

/*
 * pldebugger_language_t interface.
 */
static void plpgsql_debugger_init(void);
static bool plpgsql_frame_belongs_to_me(ErrorContextCallback *frame);
static void plpgsql_send_stack_frame(ErrorContextCallback *frame);
static void plpgsql_send_vars(ErrorContextCallback *frame);
static void plpgsql_select_frame(ErrorContextCallback *frame);
static void plpgsql_print_var(ErrorContextCallback *frame, const char *var_name, int lineno);
static bool plpgsql_do_deposit(ErrorContextCallback *frame, const char *var_name, int line_number, const char *value);
static Oid plpgsql_get_func_oid(ErrorContextCallback *frame);
static void plpgsql_send_cur_line(ErrorContextCallback *frame);

#if INCLUDE_PACKAGE_SUPPORT
debugger_language_t spl_debugger_lang =
#else
debugger_language_t plpgsql_debugger_lang =
#endif
{
	plpgsql_debugger_init,
	plpgsql_frame_belongs_to_me,
	plpgsql_send_stack_frame,
	plpgsql_send_vars,
	plpgsql_select_frame,
	plpgsql_print_var,
	plpgsql_do_deposit,
	plpgsql_get_func_oid,
	plpgsql_send_cur_line
};

/* Install this module as an PL/pgSQL instrumentation plugin */
static void
plpgsql_debugger_init(void)
{
	PLpgSQL_plugin ** var_ptr = (PLpgSQL_plugin **) find_rendezvous_variable( plugin_name );

	*var_ptr = &plugin_funcs;
}


/**********************************************************************
 * Functions implemeting the pldebugger_language_t interface
 **********************************************************************/

static bool
plpgsql_frame_belongs_to_me(ErrorContextCallback *frame)
{
	return (frame->callback == plugin_funcs.error_callback);
}

/*
 * plpgsql_send_stack_frame()
 *
 * This function sends information about a single stack frame to the debugger
 * client.  This function is called by send_stack() whenever send_stack()
 * finds a PL/pgSQL call in the stack (remember, the call stack may contain
 * stack frames for functions written in other languages like PL/Tcl).
 */
static void
plpgsql_send_stack_frame(ErrorContextCallback *frame)
{
	PLpgSQL_execstate *estate = (PLpgSQL_execstate *) frame->arg;
#if (PG_VERSION_NUM >= 80500)
	PLpgSQL_function  * func     = estate->func;
#else
	PLpgSQL_function  * func     = estate->err_func;
#endif
	PLpgSQL_stmt	  * stmt 	 = estate->err_stmt;
	int					argNameCount;
	char             ** argNames = fetchArgNames( func, &argNameCount );
	StringInfo		    result   = makeStringInfo();
	char              * delimiter = "";
	int				    arg;

	/*
	 * Send the name, function OID, and line number for this frame
	 */

	appendStringInfo( result, "%s:%d:%d:",
#if (PG_VERSION_NUM >= 90200)
					  func->fn_signature,
#else
					  func->fn_name,
#endif
					  func->fn_oid,
					  stmt->lineno );

	/*
	 * Now assemble a string that shows the argument names and value for this frame
	 */

	for( arg = 0; arg < func->fn_nargs; ++arg )
	{
		int					index   = func->fn_argvarnos[arg];
		PLpgSQL_datum		*argDatum = (PLpgSQL_datum *)estate->datums[index];
		char 				*value;

		/* value should be an empty string if argDatum is null*/
		if( datumIsNull( argDatum ))
			value = pstrdup( "" );