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pldbgapi.c
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/*
* pldbgapi.c
*
* This module defines (and implements) an API for debugging PL
* functions and procedures (in particular, functions and procedures
* written in PL/pgSQL or edb-spl).
*
* To debug a function or procedure, you need two backend processes
* plus a debugger client (the client could be a command-line client
* such as psql but is more likely a graphical client such as pgAdmin).
*
* The first backend is called the target - it's the process that's
* running the code that you want to debug.
*
* The second backend is a 'proxy' process that shuttles data between
* the debugger client and the target. The functions implemented in
* this module are called 'proxy functions'.
*
* The proxy process provides an easy and secure way for the debugger
* client to connect to the target - the client opens a normal
* libpq-style connection that (presumably) knows how to work it's
* way through a firewall and through the authentication maze (once
* the connection process completes, the debugger client is connected
* to the proxy).
*
* The debugger client can call any of the functions in this API.
* Each function is executed by the proxy process. The proxy
* shuttles debugging requests (like 'step into' or 'show call
* stack') to the debugger server (running inside of the target
* process) and sends the results back to the debugger client.
*
* There are a few basic rules for using this API:
*
* You must call one of the connection functions before you can do
* anything else (at this point, the only connection function is
* 'pldbg_attach_to_port()', but we'll add more as soon as we
* implement global breakpoints). Each connection function returns
* a session ID that identifies that debugging session (a debugger
* client can maintain multiple simultaneous sessions by keeping
* track of each session identifier). You pass that session ID
* to all of the other proxy functions.
*
* Once you have opened a session, you must wait for the target
* to reach a breakpoint (it may already be stopped at a breakpoint)
* by calling pldbg_wait_for_breakpoint( sessionID ) - that function
* will hang until the target reaches a breakpoint (or the target
* session ends).
*
* When the target pauses, you can interact with the debugger server
* (running inside of the target process) by calling any of the other
* proxy functions. For example, to tell the target to "step into" a
* function/procedure call, you would call pldbg_step_into() (and that
* function would hang until the target pauses). To tell the target
* to continue until the next breakpoint, you would call
* pldbg_continue() (and, again, that function would hang until the
* target pauses).
*
* Each time the target pauses, it returns a tuple of type 'breakpoint'.
* That tuple contains the OID of the function that the target has paused
* in, and the line number at which the target has paused. The fact that the
* target returns a tuple of type breakpoint does not imply that the target
* has paused at a breakpoint - it may have paused because of a step-over or
* step-into operation.
*
* When the target is paused at a breakpoint (or has paused after
* a step-over or step-into), you can interrogate the target by calling
* pldbg_get_stack(), pldbg_get_source(), pldbg_get_breakpoints(), or
* pldbg_get_variables().
*
* The debugger server groks the PL call stack and maintains a
* 'focus' frame. By default, the debugger server focuses on the most
* deeply nested frame (because that's the code that's actually
* running). You can shift the debugger's focus to a different frame
* by calling pldbg_select_frame().
*
* The focus is important because many functions (such as
* pldbg_get_variables()) work against the stack frame that has the focus.
*
* Any of the proxy functions may throw an error - in particular, a proxy
* function will throw an error if the target process ends. You're most
* likely to encounter an error when you call pldbg_continue() and the
* target process runs to completion (without hitting another breakpoint)
*
* Copyright (c) 2004-2013 EnterpriseDB Corporation. All Rights Reserved.
*
* Licensed under the Artistic License, see
* http://www.opensource.org/licenses/artistic-license.php
* for full details
*/
#include "postgres.h"
#include "funcapi.h"
#include "utils/memutils.h"
#include "utils/builtins.h"
#include "storage/ipc.h" /* For on_shmem_exit() */
#include "storage/proc.h" /* For MyProc */
#include "libpq/libpq-be.h" /* For Port */
#include "miscadmin.h" /* For MyProcPort */
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "access/htup.h" /* For heap_form_tuple() */
#include "access/hash.h" /* For dynahash stuff */
#include <errno.h>
#include <unistd.h> /* For close() */
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include "globalbp.h"
#include "dbgcomm.h"
/* Include header for GETSTRUCT */
#if (PG_VERSION_NUM >= 90300)
#include "access/htup_details.h"
#endif
/*
* Let the PG module loader know that we are compiled against
* the right version of the PG header files
*/
#ifdef PG_MODULE_MAGIC
PG_MODULE_MAGIC;
#endif
/*******************************************************************************
* Proxy functions
*******************************************************************************/
PG_FUNCTION_INFO_V1( pldbg_attach_to_port ); /* Attach to debugger server at the given port */
PG_FUNCTION_INFO_V1( pldbg_wait_for_breakpoint ); /* Wait for the target to reach a breakpoint */
PG_FUNCTION_INFO_V1( pldbg_step_into ); /* Steop into a function/procedure call */
PG_FUNCTION_INFO_V1( pldbg_step_over ); /* Step over a function/procedure call */
PG_FUNCTION_INFO_V1( pldbg_continue ); /* Continue execution until next breakpoint */
PG_FUNCTION_INFO_V1( pldbg_get_source ); /* Get the source code for a function/procedure */
PG_FUNCTION_INFO_V1( pldbg_get_breakpoints ); /* SHOW BREAKPOINTS equivalent (deprecated) */
PG_FUNCTION_INFO_V1( pldbg_get_variables ); /* Get a list of variable names/types/values */
PG_FUNCTION_INFO_V1( pldbg_get_stack ); /* Get the call stack from the target */
PG_FUNCTION_INFO_V1( pldbg_set_breakpoint ); /* CREATE BREAKPOINT equivalent (deprecated) */
PG_FUNCTION_INFO_V1( pldbg_drop_breakpoint ); /* DROP BREAKPOINT equivalent (deprecated) */
PG_FUNCTION_INFO_V1( pldbg_select_frame ); /* Change the focus to a different stack frame */
PG_FUNCTION_INFO_V1( pldbg_deposit_value ); /* Change the value of an in-scope variable */
PG_FUNCTION_INFO_V1( pldbg_abort_target ); /* Abort execution of the target - throws error */
PG_FUNCTION_INFO_V1( pldbg_get_proxy_info ); /* Get server version, proxy API version, ... */
PG_FUNCTION_INFO_V1( pldbg_create_listener ); /* Create a listener for global breakpoints */
PG_FUNCTION_INFO_V1( pldbg_wait_for_target ); /* Wait for a global breakpoint to fire */
PG_FUNCTION_INFO_V1( pldbg_set_global_breakpoint ); /* Create a global breakpoint */
/*******************************************************************************
* Structure debugSession
*
* A debugger client may attach to many target sessions at the same time. We
* keep track of each connection in a debugSession structure. When the client
* makes a connection, we allocate a new debugSession structure and return
* a handle to that structure to the caller. He gives us back the handle
* whenever he calls another proxy function. A handle is just a smallish
* integer value that we use to track each session - we use a hash to map
* handles into debugSession pointers.
*/
typedef struct
{
int serverSocket; /* Socket connected to the debugger server */
int serverPort; /* Port number where debugger server is listening */
int listener; /* Socket where we wait for global breakpoints */
char *breakpointString;
} debugSession;
/*******************************************************************************
* Stucture sessionHashEntry
*
* As mentioned above (see debugSession), a debugger proxy can manage many
* debug sessions at once. To keep track of each session, we create a
* debugSession object and return a handle to that object to the caller. The
* handle is an opaque value - it's just an integer value. To convert a
* handle into an actual debugSession pointer, we create a hash that maps
* handles into debugSession pointers.
*
* Each member of the hash is shaped like a sessionHashEntry object.
*/
typedef int32 sessionHandle;
typedef struct
{
sessionHandle m_handle;
debugSession *m_session;
} sessionHashEntry;
static debugSession * mostRecentSession;
static HTAB * sessionHash;
/*******************************************************************************
* The following symbols represent the magic strings that we send to the
* debugger server running in the target process
*/
#define PLDBG_GET_VARIABLES "i\n"
#define PLDBG_GET_BREAKPOINTS "l\n"
#define PLDBG_GET_STACK "$\n"
#define PLDBG_STEP_INTO "s\n"
#define PLDBG_STEP_OVER "o\n"
#define PLDBG_CONTINUE "c\n"
#define PLDBG_ABORT "x"
#define PLDBG_SELECT_FRAME "^" /* Followed by frame number */
#define PLDBG_SET_BREAKPOINT "b" /* Followed by pkgoid:funcoid:linenumber */
#define PLDBG_CLEAR_BREAKPOINT "f" /* Followed by pkgoid:funcoid:linenumber */
#define PLDBG_GET_SOURCE "#" /* Followed by pkgoid:funcoid */
#define PLDBG_DEPOSIT "d" /* Followed by var.line=value */
#define PROXY_API_VERSION 3 /* API version number */
/*******************************************************************************
* We currently define three PostgreSQL data types (all tuples) - the following
* symbols correspond to the names for those types.
*/
#define TYPE_NAME_BREAKPOINT "breakpoint" /* May change to pldbg.breakpoint later */
#define TYPE_NAME_FRAME "frame" /* May change to pldbg.frame later */
#define TYPE_NAME_VAR "var" /* May change to pldbg.var later */
#define GET_STR( textp ) DatumGetCString( DirectFunctionCall1( textout, PointerGetDatum( textp )))
#define PG_GETARG_SESSION( n ) (sessionHandle)PG_GETARG_UINT32( n )
Datum pldbg_select_frame( PG_FUNCTION_ARGS );
Datum pldbg_attach_to_port( PG_FUNCTION_ARGS );
Datum pldbg_get_source( PG_FUNCTION_ARGS );
Datum pldbg_get_breakpoints( PG_FUNCTION_ARGS );
Datum pldbg_get_variables( PG_FUNCTION_ARGS );
Datum pldbg_get_stack( PG_FUNCTION_ARGS );
Datum pldbg_wait_for_breakpoint( PG_FUNCTION_ARGS );
Datum pldbg_set_breakpoint( PG_FUNCTION_ARGS );
Datum pldbg_drop_breakpoint( PG_FUNCTION_ARGS );
Datum pldbg_step_into( PG_FUNCTION_ARGS );
Datum pldbg_step_over( PG_FUNCTION_ARGS );
Datum pldbg_continue( PG_FUNCTION_ARGS );
Datum pldbg_deposit_value( PG_FUNCTION_ARGS );
Datum pldbg_get_proxy_info( PG_FUNCTION_ARGS );
Datum pldbg_get_pkg_cons( PG_FUNCTION_ARGS );
Datum pldbg_abort_target( PG_FUNCTION_ARGS );
Datum pldbg_create_listener( PG_FUNCTION_ARGS );
Datum pldbg_wait_for_target( PG_FUNCTION_ARGS );
Datum pldbg_set_global_breakpoint( PG_FUNCTION_ARGS );
/************************************************************
* Local function forward declarations
************************************************************/
static char * tokenize( char * src, const char * delimiters, char ** ctx );
static void * readn( int serverHandle, void * dst, size_t len );
static void * writen( int serverHandle, void * dst, size_t len );
static void sendBytes( debugSession * session, void * src, size_t len );
static void sendUInt32( debugSession * session, uint32 val );
static void sendString( debugSession * session, char * src );
static bool getBool( debugSession * session );
static uint32 getUInt32( debugSession * session );
static char * getNString( debugSession * session );
static void initializeModule( void );
static void cleanupAtExit( int code, Datum arg );
static void initSessionHash();
static debugSession * defaultSession( sessionHandle handle );
static sessionHandle addSession( debugSession * session );
static debugSession * findSession( sessionHandle handle );
static TupleDesc getResultTupleDesc( FunctionCallInfo fcinfo );
/*******************************************************************************
* Exported functions
*******************************************************************************/
/*******************************************************************************
* pldbg_attach_to_port( portNumber INTEGER ) RETURNS INTEGER
*
* This function attaches to a debugging target listening on the given port. A
* debugger client should invoke this function in response to a PLDBGBREAK
* NOTICE (the notice contains the port number that you should connect to).
*
* This function returns a session handle that identifies this particular debug
* session. When you call any of the other pldbg functions, you must supply
* the session handle returned by pldbg_attach_to_port().
*
* A given debugger client can maintain multiple simultaneous sessions
* by calling pldbg_attach_to_port() many times (with different port
* numbers) and keeping track of the returned session handles.
*/
Datum pldbg_attach_to_port( PG_FUNCTION_ARGS )
{
int32 targetBackend = PG_GETARG_INT32( 0 );
debugSession *session;
initializeModule();
session = MemoryContextAllocZero( TopMemoryContext, sizeof( *session ));
session->listener = -1;
session->serverSocket = dbgcomm_connect_to_target(targetBackend);
if (session->serverSocket < 0)
ereport(ERROR,
(errcode_for_socket_access(),
errmsg("could not connect to debug target")));
/*
* After the handshake, the target process will send us information about
* the local breakpoint that it hit. Read it. We will hand it to the client
* if it calls wait_for_breakpoint().
*/
session->breakpointString = MemoryContextStrdup(TopMemoryContext,
getNString(session));
/*
* For convenience, remember the most recent session - if you call
* another pldbg_xxx() function with sessionHandle = 0, we'll use
* the most recent session.
*/
mostRecentSession = session;
PG_RETURN_INT32(addSession(session));
}
Datum pldbg_create_listener( PG_FUNCTION_ARGS )
{
debugSession * session = MemoryContextAllocZero( TopMemoryContext, sizeof( *session ));
initializeModule();
session->listener = dbgcomm_listen_for_target(&session->serverPort);
session->serverSocket = -1;
mostRecentSession = session;
PG_RETURN_INT32( addSession( session ));
}
/*******************************************************************************
* pldbg_wait_for_target( ) RETURNS INTEGER
*
* This function advertises the proxy process as an active debugger, waiting
* for global breakpoints.
*
* This function returns a session handle that identifies this particular debug
* session. When you call any of the other pldbg functions, you must supply
* this session handle.
*
* A given debugger client can maintain multiple simultaneous sessions
* by calling pldbg_attach_to_port() many times (with different port
* numbers) and keeping track of the returned session handles.
*/
Datum pldbg_wait_for_target( PG_FUNCTION_ARGS )
{
debugSession *session = defaultSession(PG_GETARG_SESSION( 0 ));
int serverSocket;
int serverPID;
/*
* Now mark all of our global breakpoints as 'available' (that is, not
* busy)
*/
BreakpointFreeSession( MyProc->pid );
serverSocket = dbgcomm_accept_target(session->listener, &serverPID);
if (serverSocket < 0)
ereport(ERROR,
(errmsg("could not accept a connection from debugging target")));
session->serverSocket = serverSocket;
/*
* After the handshake, the target process will send us information about
* the local breakpoint that it hit. Read it. We will hand it to the client
* if it calls wait_for_breakpoint().
*/
session->breakpointString = MemoryContextStrdup(TopMemoryContext,
getNString(session));
PG_RETURN_UINT32( serverPID );
}
/*******************************************************************************
* pldbg_set_global_breakpoint(sessionID INT, function OID, lineNumber INT)
* RETURNS boolean
*
* This function registers a breakpoint in the global breakpoint table.
*/
Datum pldbg_set_global_breakpoint( PG_FUNCTION_ARGS )
{
debugSession * session = defaultSession( PG_GETARG_SESSION( 0 ));
Breakpoint breakpoint;
if( !superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("must be a superuser to create a breakpoint")));
if( session->listener == -1 )
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("given session is not a listener")));
breakpoint.key.databaseId = MyProc->databaseId;
breakpoint.key.functionId = PG_GETARG_OID( 1 );
if( PG_ARGISNULL( 2 ))
breakpoint.key.lineNumber = -1;
else
breakpoint.key.lineNumber = PG_GETARG_INT32( 2 );
if( PG_ARGISNULL( 3 ))
breakpoint.key.targetPid = -1;
else
breakpoint.key.targetPid = PG_GETARG_INT32( 3 );
breakpoint.data.isTmp = TRUE;
breakpoint.data.proxyPort = session->serverPort;
breakpoint.data.proxyPid = MyProc->pid;
if( !BreakpointInsert( BP_GLOBAL, &breakpoint.key, &breakpoint.data ))
ereport(ERROR,
(errcode(ERRCODE_OBJECT_IN_USE),
errmsg("another debugger is already waiting for that breakpoint")));
PG_RETURN_BOOL( true );
}
/*******************************************************************************
* pldbg_wait_for_breakpoint( sessionID INTEGER ) RETURNS breakpoint
*
* This function waits for the debug target to reach a breakpoint. You should
* call this function immediately after pldbg_attach_to_port() returns a
* session ID. pldbg_wait_for_breakpoint() is nearly identical to
* pldbg_step_into(), pldbg_step_over(), and pldbg_continue(), (they all wait
* for the target) but this function does not send a command to the target
* first.
*
* This function returns a tuple of type 'breakpoint' - such a tuple contains
* the function OID and line number where the target is currently stopped.
*/
static Datum buildBreakpointDatum( char * breakpointString )
{
char * values[3];
char * ctx = NULL;
HeapTuple result;
TupleDesc tupleDesc = RelationNameGetTupleDesc( TYPE_NAME_BREAKPOINT );
values[0] = tokenize( breakpointString, ":", &ctx ); /* function OID */
values[1] = tokenize( NULL, ":", &ctx ); /* linenumber */
values[2] = tokenize( NULL, ":", &ctx ); /* targetName */
result = BuildTupleFromCStrings( TupleDescGetAttInMetadata( tupleDesc ), values );
return( HeapTupleGetDatum( result ));
}
Datum pldbg_wait_for_breakpoint( PG_FUNCTION_ARGS )
{
debugSession * session = defaultSession( PG_GETARG_SESSION( 0 ));
char * breakpointString;
if (!session->breakpointString)
PG_RETURN_NULL();
breakpointString = pstrdup(session->breakpointString);
pfree(session->breakpointString);
session->breakpointString = NULL;
PG_RETURN_DATUM( buildBreakpointDatum( breakpointString ));
}
/*******************************************************************************
* pldbg_step_into( sessionID INTEGER ) RETURNS breakpoint
*
* This function sends a "step/into" command to the debugger target and then
* waits for target to reach the next executable statement.
*
* This function returns a tuple of type 'breakpoint' that contains the
* function OID and line number where the target is currently stopped.
*/
Datum pldbg_step_into( PG_FUNCTION_ARGS )
{
debugSession * session = defaultSession( PG_GETARG_SESSION( 0 ));
sendString( session, PLDBG_STEP_INTO );
PG_RETURN_DATUM( buildBreakpointDatum( getNString( session )));
}
/*******************************************************************************
* pldbg_step_over( sessionID INTEGER ) RETURNS breakpoint
*
* This function sends a "step/over" command to the debugger target and then
* waits for target to reach the next executable statement within the current
* function. If the target encounters a breakpoint (presumably in a child
* invocation) before reaching the next executable line, it will stop at the
* breakpoint.
*
* This function returns a tuple of type 'breakpoint' that contains the
* function OID and line number where the target is currently stopped.
*/
Datum pldbg_step_over( PG_FUNCTION_ARGS )
{
debugSession * session = defaultSession( PG_GETARG_SESSION( 0 ));
sendString( session, PLDBG_STEP_OVER );
PG_RETURN_DATUM( buildBreakpointDatum( getNString( session )));
}
/*******************************************************************************
* pldbg_continue( sessionID INTEGER ) RETURNS breakpoint
*
* This function sends a "continue" command to the debugger target and then
* waits for target to reach a breakpoint.
*
* This function returns a tuple of type 'breakpoint' that contains the
* function OID and line number where the target is currently stopped.
*/
Datum pldbg_continue( PG_FUNCTION_ARGS )
{
debugSession * session = defaultSession( PG_GETARG_SESSION( 0 ));
sendString( session, PLDBG_CONTINUE );
PG_RETURN_DATUM( buildBreakpointDatum( getNString( session )));
}
/*******************************************************************************
* pldbg_abort_target( sessionID INTEGER ) RETURNS breakpoint
*
* This function sends an "abort" command to the debugger target and then
* waits for a reply
*/
Datum pldbg_abort_target( PG_FUNCTION_ARGS )
{
debugSession * session = defaultSession( PG_GETARG_SESSION( 0 ));
sendString( session, PLDBG_ABORT );
PG_RETURN_BOOL( getBool( session ));
}
/*******************************************************************************
* pldbg_select_frame( sessionID INTEGER, frameNumber INTEGER )
* RETURNS breakpoint
*
* This function changes the debugger focus to the indicated frame (in the call
* stack). Whenever the target stops (at a breakpoint or as the result of a
* step/into or step/over), the debugger changes focus to most deeply nested
* function in the call stack (because that's the function that's executing).
*
* You can change the debugger focus to other stack frames - once you do that,
* you can examine the source code for that frame, the variable values in that
* frame, and the breakpoints in that target.
*
* The debugger focus remains on the selected frame until you change it or
* the target stops at another breakpoint.
*
* This function returns a tuple of type 'breakpoint' that contains the
* function OID, and line number where the target is currently stopped in
* the selected frame.
*/
Datum pldbg_select_frame( PG_FUNCTION_ARGS )
{
if( PG_ARGISNULL( 0 ))
PG_RETURN_NULL();
else
{
debugSession * session = defaultSession( PG_GETARG_SESSION( 0 ));
int32 frameNumber = PG_GETARG_INT32( 1 );
char frameString[12]; /* sign, 10 digits, '\0' */
char * resultString;
Datum result;
sprintf( frameString, "%s %d", PLDBG_SELECT_FRAME, frameNumber );
sendString( session, frameString );
resultString = getNString( session );
result = buildBreakpointDatum( resultString );
PG_RETURN_DATUM( result );
}
}
/*******************************************************************************
* pldbg_get_source( sessionID INTEGER, functionOID OID )
* RETURNS CSTRING
*
* This function returns the source code for the given function. A debugger
* client should always retrieve source code using this function instead of
* reading pg_proc. If you read pg_proc instead, the source code that you
* read may not match the source that the target is actually executing
* (because the source code may have been modified in a different transaction).
*
* pldbg_get_source() always retrieves the source code from the target and
* ensures that the source code that you get is the source code that the
* target is executing.
*
*/
Datum pldbg_get_source( PG_FUNCTION_ARGS )
{
debugSession * session = defaultSession( PG_GETARG_SESSION( 0 ));
Oid funcOID = PG_GETARG_OID( 1 );
char sourceString[13]; /* 10 digits(oid) + space + 1 command + null terminator */
char * source;
sprintf( sourceString, "%s %d", PLDBG_GET_SOURCE, funcOID );
sendString( session, sourceString );
source = getNString( session );
PG_RETURN_TEXT_P(cstring_to_text(source));
}
/*******************************************************************************
* pldbg_get_breakpoints( sessionID INTEGER ) RETURNS SETOF breakpoint
*
* This function returns a SETOF breakpoint tuples. Each tuple in the result
* set identifies a breakpoint.
*
* NOTE: the result set returned by this function should be identical to
* the result set returned by a SHOW BREAKPOINTS command. This function
* may become obsolete when SHOW BREAKPOINTS is complete.
*/
Datum pldbg_get_breakpoints( PG_FUNCTION_ARGS )
{
FuncCallContext * srf;
debugSession * session = defaultSession( PG_GETARG_SESSION( 0 ));
char * breakpointString;
if( SRF_IS_FIRSTCALL())
{
MemoryContext oldContext;
srf = SRF_FIRSTCALL_INIT();
oldContext = MemoryContextSwitchTo( srf->multi_call_memory_ctx );
srf->attinmeta = TupleDescGetAttInMetadata( RelationNameGetTupleDesc( TYPE_NAME_BREAKPOINT ));
MemoryContextSwitchTo( oldContext );
sendString( session, PLDBG_GET_BREAKPOINTS );
}
else
{
srf = SRF_PERCALL_SETUP();
}
if(( breakpointString = getNString( session )) != NULL )
{
SRF_RETURN_NEXT( srf, buildBreakpointDatum( breakpointString ));
}
else
{
SRF_RETURN_DONE( srf );
}
}
/*******************************************************************************
* pldbg_get_variables( sessionID INTEGER ) RETURNS SETOF var
*
* This function returns a SETOF var tuples. Each tuple in the result
* set contains information about one local variable (or parameter) in the
* stack frame that has the focus. Each tuple contains the name of the
* variable, the line number at which the variable was declared, a flag
* that tells you whether the name is unique within the scope of the function
* (if the name is not unique, a debugger client may use the line number to
* distinguish between variables with the same name), a flag that tells you
* whether the variables is a CONST, a flag that tells you whether the variable
* is NOT NULL, the data type of the variable (the OID of the corresponding
* pg_type) and the value of the variable.
*
* To view variables defined in a different stack frame, call
* pldbg_select_frame() to change the debugger's focus to that frame.
*/
Datum pldbg_get_variables( PG_FUNCTION_ARGS )
{
FuncCallContext * srf;
debugSession * session = defaultSession( PG_GETARG_SESSION( 0 ));
char * variableString;
if( SRF_IS_FIRSTCALL())
{
MemoryContext oldContext;
srf = SRF_FIRSTCALL_INIT();
oldContext = MemoryContextSwitchTo( srf->multi_call_memory_ctx );
srf->attinmeta = TupleDescGetAttInMetadata( RelationNameGetTupleDesc( TYPE_NAME_VAR ));
MemoryContextSwitchTo( oldContext );
sendString( session, PLDBG_GET_VARIABLES );
}
else
{
srf = SRF_PERCALL_SETUP();
}
if(( variableString = getNString( session )) != NULL )
{
char * values[8];
char * ctx = NULL;
HeapTuple result;
/*
* variableString points to a string like:
* varName:class:lineNumber:unique:isConst:notNull:dataTypeOID
*/
values[0] = pstrdup( tokenize( variableString, ":", &ctx )); /* variable name */
values[1] = pstrdup( tokenize( NULL, ":", &ctx )); /* var class */
values[2] = pstrdup( tokenize( NULL, ":", &ctx )); /* line number */
values[3] = pstrdup( tokenize( NULL, ":", &ctx )); /* unique */
values[4] = pstrdup( tokenize( NULL, ":", &ctx )); /* isConst */
values[5] = pstrdup( tokenize( NULL, ":", &ctx )); /* notNull */
values[6] = pstrdup( tokenize( NULL, ":", &ctx )); /* data type OID */
values[7] = pstrdup( tokenize( NULL, NULL, &ctx )); /* value (rest of string) */
result = BuildTupleFromCStrings( srf->attinmeta, values );
SRF_RETURN_NEXT( srf, HeapTupleGetDatum( result ));
}
else
{
SRF_RETURN_DONE( srf );
}
}
/*******************************************************************************
* pldbg_get_stack( sessionID INTEGER ) RETURNS SETOF frame
*
* This function returns a SETOF frame tuples. Each tuple in the result
* set contains information about one stack frame: the tuple contains the
* function OID, and line number within that function. Each tuple also
* contains a string that you can use to display the name and value of each
* argument to that particular invocation.
*/
Datum pldbg_get_stack( PG_FUNCTION_ARGS )
{
FuncCallContext * srf;
debugSession * session = defaultSession( PG_GETARG_SESSION( 0 ));
char * frameString;
if( SRF_IS_FIRSTCALL())
{
MemoryContext oldContext;
srf = SRF_FIRSTCALL_INIT();
oldContext = MemoryContextSwitchTo( srf->multi_call_memory_ctx );
srf->attinmeta = TupleDescGetAttInMetadata( RelationNameGetTupleDesc( TYPE_NAME_FRAME ));
MemoryContextSwitchTo( oldContext );
sendString( session, PLDBG_GET_STACK );
}
else
{
srf = SRF_PERCALL_SETUP();
}
if(( frameString = getNString( session )) != NULL )
{
char * values[5];
char callCount[10+1];
char * ctx = NULL;
HeapTuple result;
/*
* frameString points to a string like:
* targetName:funcOID:lineNumber:arguments
*/
sprintf( callCount, "%d", srf->call_cntr );
values[0] = callCount;
values[1] = tokenize( frameString, ":", &ctx ); /* targetName */
values[2] = tokenize( NULL, ":", &ctx ); /* funcOID */
values[3] = tokenize( NULL, ":", &ctx ); /* lineNumber */
values[4] = tokenize( NULL, NULL, &ctx ); /* arguments - rest of string */
result = BuildTupleFromCStrings( srf->attinmeta, values );
SRF_RETURN_NEXT( srf, HeapTupleGetDatum( result ));
}
else
{
SRF_RETURN_DONE( srf );
}
}
/********************************************************************************
* pldbg_get_proxy_info( ) RETURNS proxyInfo
*
* This function retrieves a small collection of parameters from the server, all
* parameters are related to the version of the server and the version of this
* proxy API.
*
* You can call this function (from the debugger client process) to find out
* which version of the proxy API you are talking to - if this function does
* not exist, you can assume that you are talking to a version 1 proxy server.
*/
Datum pldbg_get_proxy_info( PG_FUNCTION_ARGS )
{
Datum values[4] = {0};
bool nulls[4] = {0};
TupleDesc tupleDesc = getResultTupleDesc( fcinfo );
HeapTuple result;
values[0] = DirectFunctionCall1( textin, PointerGetDatum( PG_VERSION_STR ));
values[1] = Int32GetDatum( PG_VERSION_NUM );
values[2] = Int32GetDatum( PROXY_API_VERSION );
values[3] = Int32GetDatum( MyProcPid );
result = heap_form_tuple( tupleDesc, values, nulls );
PG_RETURN_DATUM( HeapTupleGetDatum( result ));
}
/*******************************************************************************
* pldbg_set_breakpoint(sessionID INT, function OID, lineNumber INT)
* RETURNS boolean
*
* Sets a *local* breakpoint in the target process.
*/
Datum pldbg_set_breakpoint( PG_FUNCTION_ARGS )
{
debugSession * session = defaultSession( PG_GETARG_SESSION( 0 ));
Oid funcOID = PG_GETARG_OID( 1 );
int lineNumber = PG_GETARG_INT32( 2 );
char breakpointString[24]; /* 20 digits + 2 delimiters + 1 command + null terminator */
sprintf( breakpointString, "%s %d:%d", PLDBG_SET_BREAKPOINT, funcOID, lineNumber );
sendString( session, breakpointString );
PG_RETURN_BOOL( getBool( session ));
}
/*******************************************************************************
* pldbg_drop_breakpoint(sessionID INT, function OID, lineNumber INT)
* RETURNS boolean
*/
Datum pldbg_drop_breakpoint( PG_FUNCTION_ARGS )
{
debugSession * session = defaultSession( PG_GETARG_SESSION( 0 ));
Oid funcOID = PG_GETARG_OID( 1 );
int lineNumber = PG_GETARG_INT32( 2 );
char breakpointString[13]; /* 10 digits + 1 delimiters + 1 command + null terminator */
sprintf( breakpointString, "%s %d:%d", PLDBG_CLEAR_BREAKPOINT, funcOID, lineNumber );
sendString( session, breakpointString );
PG_RETURN_BOOL( getBool( session ));
}
/*******************************************************************************
* pldbg_deposit_value( sessionID INT, varName TEXT, lineNumber INT, value TEXT)
* RETURNS boolean
*
* This function 'deposits' a new value into the given variable (identified by
* name and optional line number). 'value' is evaluated as an expression that
* must result in a value whose type matches the given variable (or whose type
* is coerce'able to the type of the given variable).
*/
Datum pldbg_deposit_value( PG_FUNCTION_ARGS )
{
debugSession * session = defaultSession( PG_GETARG_SESSION( 0 ));
char * varName = GET_STR( PG_GETARG_TEXT_P( 1 ));
int lineNumber = PG_GETARG_INT32( 2 );
char * value = GET_STR( PG_GETARG_TEXT_P( 3 ));
StringInfoData buf;
initStringInfo( &buf );
appendStringInfo( &buf, "%s %s.%d=%s", PLDBG_DEPOSIT, varName, lineNumber, value );
sendString( session, buf.data );
pfree( buf.data );
PG_RETURN_BOOL( getBool( session ));
}
/*******************************************************************************
* Local supporting (static) functions
*******************************************************************************/
/*******************************************************************************
* initializeModule()
*
* Initializes the debugger proxy module. For now, we just register a callback
* (cleanupAtExit()) that this backend will invoke on exit - we use that
* callback to gracefully close any outstanding connections.
*
* NOTE: this would also be a good place to load the tuple descriptions for
* each of the complex datatypes that we use (breakpoint, var, frame).
*/
static void initializeModule( void )
{
static bool initialized = FALSE;
if( !initialized )
{
initialized = TRUE;
on_shmem_exit( cleanupAtExit, 0 );
}
}
/*******************************************************************************
* defaultSession()
*
* This function is designed to make it a little easier to build a simple
* debugger client. Instead of managing session identifiers, you can simply
* pass '0' to each function that requires a session ID. When a proxy function
* encounters a session ID of 0, it assumes that you want to work with the most
* recently used session. If you have only one session, you can simply pass
* '0' to every function. This is particularly handy if you're using the proxy
* API from a command line application like psql.
*
* NOTE: If you give this function an invalid sessionHandle it will throw an
* error. A sessionHandle is valid if returned by addSession().
*/
static debugSession * defaultSession( sessionHandle handle )
{
debugSession * session;
if( handle == 0 )
{
if( mostRecentSession == NULL )
ereport( ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg( "invalid session handle" )));
else
return( mostRecentSession );
}
else
{
session = findSession( handle );
if( session == NULL )
ereport( ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg( "invalid session handle" )));
else
{
mostRecentSession = session;
return( session );
}
}
return( NULL ); /* keep the compiler happy */
}
/*******************************************************************************
* initSessionHash()
*
* Initialize a hash table that we use to map session handles (simple integer
* values) into debugSession pointers.
*
* You should call this function before you use the hash - you can call it
* as many times as you like, it will only initialize the hash table on the
* first invocation.
*/
static void initSessionHash()
{
if( sessionHash )
return;
else
{
HASHCTL ctl = {0};
ctl.keysize = sizeof( sessionHandle );
ctl.entrysize = sizeof( sessionHashEntry );
ctl.hash = tag_hash;
sessionHash = hash_create( "Debugger sessions", 5, &ctl, HASH_ELEM | HASH_FUNCTION );
}