/*-------------------------------------------------------------------------

 *

 * fastpath.c

 *    routines to handle function requests from the frontend

 *

 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group

 * Portions Copyright (c) 1994, Regents of the University of California

 *

 *

 * IDENTIFICATION

 *    src/backend/tcop/fastpath.c

 *

 * NOTES

 *    This cruft is the server side of PQfn.

 *

 *-------------------------------------------------------------------------

 */

#include "postgres.h"

#include "access/htup_details.h"

#include "access/xact.h"

#include "catalog/objectaccess.h"

#include "catalog/pg_namespace.h"

#include "catalog/pg_proc.h"

#include "libpq/pqformat.h"

#include "libpq/protocol.h"

#include "mb/pg_wchar.h"

#include "miscadmin.h"

#include "tcop/fastpath.h"

#include "tcop/tcopprot.h"

#include "utils/acl.h"

#include "utils/lsyscache.h"

#include "utils/snapmgr.h"

#include "utils/syscache.h"

/*

 * Formerly, this code attempted to cache the function and type info

 * looked up by fetch_fp_info, but only for the duration of a single

 * transaction command (since in theory the info could change between

 * commands).  This was utterly useless, because postgres.c executes

 * each fastpath call as a separate transaction command, and so the

 * cached data could never actually have been reused.  If it had worked

 * as intended, it would have had problems anyway with dangling references

 * in the FmgrInfo struct.  So, forget about caching and just repeat the

 * syscache fetches on each usage.  They're not *that* expensive.

 */

struct fp_info

{

  Oid     funcid;

  FmgrInfo  flinfo;     /* function lookup info for funcid */

  Oid     namespace;    /* other stuff from pg_proc */

  Oid     rettype;

  Oid     argtypes[FUNC_MAX_ARGS];

  char    fname[NAMEDATALEN]; /* function name for logging */

};

static int16 parse_fcall_arguments(StringInfo msgBuf, struct fp_info *fip,

                   FunctionCallInfo fcinfo);

/* ----------------

 *    SendFunctionResult

 * ----------------

 */

static void

SendFunctionResult(Datum retval, bool isnull, Oid rettype, int16 format)

{

  StringInfoData buf;

  pq_beginmessage(&buf, PqMsg_FunctionCallResponse);

  if (isnull)

  {

    pq_sendint32(&buf, -1);

  }

  else

  {

    if (format == 0)

    {

      Oid     typoutput;

      bool    typisvarlena;

      char     *outputstr;

      getTypeOutputInfo(rettype, &typoutput, &typisvarlena);

      outputstr = OidOutputFunctionCall(typoutput, retval);

      pq_sendcountedtext(&buf, outputstr, strlen(outputstr));

      pfree(outputstr);

    }

    else if (format == 1)

    {

      Oid     typsend;

      bool    typisvarlena;

      bytea    *outputbytes;

      getTypeBinaryOutputInfo(rettype, &typsend, &typisvarlena);

      outputbytes = OidSendFunctionCall(typsend, retval);

      pq_sendint32(&buf, VARSIZE(outputbytes) - VARHDRSZ);

      pq_sendbytes(&buf, VARDATA(outputbytes),

             VARSIZE(outputbytes) - VARHDRSZ);

      pfree(outputbytes);

    }

    else

      ereport(ERROR,

          (errcode(ERRCODE_INVALID_PARAMETER_VALUE),

           errmsg("unsupported format code: %d", format)));

  }

  pq_endmessage(&buf);

}

/*

 * fetch_fp_info

 *

 * Performs catalog lookups to load a struct fp_info 'fip' for the

 * function 'func_id'.

 */

static void

fetch_fp_info(Oid func_id, struct fp_info *fip)

{

  HeapTuple func_htp;

  Form_pg_proc pp;

  Assert(fip != NULL);

  /*

   * Since the validity of this structure is determined by whether the

   * funcid is OK, we clear the funcid here.  It must not be set to the

   * correct value until we are about to return with a good struct fp_info,

   * since we can be interrupted (i.e., with an ereport(ERROR, ...)) at any

   * time.  [No longer really an issue since we don't save the struct

   * fp_info across transactions anymore, but keep it anyway.]

   */

  MemSet(fip, 0, sizeof(struct fp_info));

  fip->funcid = InvalidOid;

  func_htp = SearchSysCache1(PROCOID, ObjectIdGetDatum(func_id));

  if (!HeapTupleIsValid(func_htp))

    ereport(ERROR,

        (errcode(ERRCODE_UNDEFINED_FUNCTION),

         errmsg("function with OID %u does not exist", func_id)));

  pp = (Form_pg_proc) GETSTRUCT(func_htp);

  /* reject pg_proc entries that are unsafe to call via fastpath */

  if (pp->prokind != PROKIND_FUNCTION || pp->proretset)

    ereport(ERROR,

        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),

         errmsg("cannot call function \"%s\" via fastpath interface",

            NameStr(pp->proname))));

  /* watch out for catalog entries with more than FUNC_MAX_ARGS args */

  if (pp->pronargs > FUNC_MAX_ARGS)

    elog(ERROR, "function %s has more than %d arguments",

       NameStr(pp->proname), FUNC_MAX_ARGS);

  fip->namespace = pp->pronamespace;

  fip->rettype = pp->prorettype;

  memcpy(fip->argtypes, pp->proargtypes.values, pp->pronargs * sizeof(Oid));

  strlcpy(fip->fname, NameStr(pp->proname), NAMEDATALEN);

  ReleaseSysCache(func_htp);

  fmgr_info(func_id, &fip->flinfo);

  /*

   * This must be last!

   */

  fip->funcid = func_id;

}

/*

 * HandleFunctionRequest

 *

 * Server side of PQfn (fastpath function calls from the frontend).

 * This corresponds to the libpq protocol symbol "F".

 *

 * INPUT:

 *    postgres.c has already read the message body and will pass it in

 *    msgBuf.

 *

 * Note: palloc()s done here and in the called function do not need to be

 * cleaned up explicitly.  We are called from PostgresMain() in the

 * MessageContext memory context, which will be automatically reset when

 * control returns to PostgresMain.

 */

void

HandleFunctionRequest(StringInfo msgBuf)

{

  LOCAL_FCINFO(fcinfo, FUNC_MAX_ARGS);

  Oid     fid;

  AclResult aclresult;

  int16   rformat;

  Datum   retval;

  struct fp_info my_fp;

  struct fp_info *fip;

  bool    callit;

  bool    was_logged = false;

  char    msec_str[32];

  /*

   * We only accept COMMIT/ABORT if we are in an aborted transaction, and

   * COMMIT/ABORT cannot be executed through the fastpath interface.

   */

  if (IsAbortedTransactionBlockState())

    ereport(ERROR,

        (errcode(ERRCODE_IN_FAILED_SQL_TRANSACTION),

         errmsg("current transaction is aborted, "

            "commands ignored until end of transaction block")));

  /*

   * Now that we know we are in a valid transaction, set snapshot in case

   * needed by function itself or one of the datatype I/O routines.

   */

  PushActiveSnapshot(GetTransactionSnapshot());

  /*

   * Begin parsing the buffer contents.

   */

  fid = (Oid) pq_getmsgint(msgBuf, 4);  /* function oid */

  /*

   * There used to be a lame attempt at caching lookup info here. Now we

   * just do the lookups on every call.

   */

  fip = &my_fp;

  fetch_fp_info(fid, fip);

  /* Log as soon as we have the function OID and name */

  if (log_statement == LOGSTMT_ALL)

  {

    ereport(LOG,

        (errmsg("fastpath function call: \"%s\" (OID %u)",

            fip->fname, fid)));

    was_logged = true;

  }

  /*

   * Check permission to access and call function.  Since we didn't go

   * through a normal name lookup, we need to check schema usage too.

   */

  aclresult = object_aclcheck(NamespaceRelationId, fip->namespace, GetUserId(), ACL_USAGE);

  if (aclresult != ACLCHECK_OK)

    aclcheck_error(aclresult, OBJECT_SCHEMA,

             get_namespace_name(fip->namespace));

  InvokeNamespaceSearchHook(fip->namespace, true);

  aclresult = object_aclcheck(ProcedureRelationId, fid, GetUserId(), ACL_EXECUTE);

  if (aclresult != ACLCHECK_OK)

    aclcheck_error(aclresult, OBJECT_FUNCTION,

             get_func_name(fid));

  InvokeFunctionExecuteHook(fid);

  /*

   * Prepare function call info block and insert arguments.

   *

   * Note: for now we pass collation = InvalidOid, so collation-sensitive

   * functions can't be called this way.  Perhaps we should pass

   * DEFAULT_COLLATION_OID, instead?

   */

  InitFunctionCallInfoData(*fcinfo, &fip->flinfo, 0, InvalidOid, NULL, NULL);

  rformat = parse_fcall_arguments(msgBuf, fip, fcinfo);

  /* Verify we reached the end of the message where expected. */

  pq_getmsgend(msgBuf);

  /*

   * If func is strict, must not call it for null args.

   */

  callit = true;

  if (fip->flinfo.fn_strict)

  {

    int     i;

    for (i = 0; i < fcinfo->nargs; i++)

    {

      if (fcinfo->args[i].isnull)

      {

        callit = false;

        break;

      }

    }

  }

  if (callit)

  {

    /* Okay, do it ... */

    retval = FunctionCallInvoke(fcinfo);

  }

  else

  {

    fcinfo->isnull = true;

    retval = (Datum) 0;

  }

  /* ensure we do at least one CHECK_FOR_INTERRUPTS per function call */

  CHECK_FOR_INTERRUPTS();

  SendFunctionResult(retval, fcinfo->isnull, fip->rettype, rformat);

  /* We no longer need the snapshot */

  PopActiveSnapshot();

  /*

   * Emit duration logging if appropriate.

   */

  switch (check_log_duration(msec_str, was_logged))

  {

    case 1:

      ereport(LOG,

          (errmsg("duration: %s ms", msec_str)));

      break;

    case 2:

      ereport(LOG,

          (errmsg("duration: %s ms  fastpath function call: \"%s\" (OID %u)",

              msec_str, fip->fname, fid)));

      break;

  }

}

/*

 * Parse function arguments in a 3.0 protocol message

 *

 * Argument values are loaded into *fcinfo, and the desired result format

 * is returned.

 */

static int16

parse_fcall_arguments(StringInfo msgBuf, struct fp_info *fip,

            FunctionCallInfo fcinfo)

{

  int     nargs;

  int     i;

  int     numAFormats;

  int16    *aformats = NULL;

  StringInfoData abuf;

  /* Get the argument format codes */

  numAFormats = pq_getmsgint(msgBuf, 2);

  if (numAFormats > 0)

  {

    aformats = (int16 *) palloc(numAFormats * sizeof(int16));

    for (i = 0; i < numAFormats; i++)

      aformats[i] = pq_getmsgint(msgBuf, 2);

  }

  nargs = pq_getmsgint(msgBuf, 2);  /* # of arguments */

  if (fip->flinfo.fn_nargs != nargs || nargs > FUNC_MAX_ARGS)

    ereport(ERROR,

        (errcode(ERRCODE_PROTOCOL_VIOLATION),

         errmsg("function call message contains %d arguments but function requires %d",

            nargs, fip->flinfo.fn_nargs)));

  fcinfo->nargs = nargs;

  if (numAFormats > 1 && numAFormats != nargs)

    ereport(ERROR,

        (errcode(ERRCODE_PROTOCOL_VIOLATION),

         errmsg("function call message contains %d argument formats but %d arguments",

            numAFormats, nargs)));

  initStringInfo(&abuf);

  /*

   * Copy supplied arguments into arg vector.

   */

  for (i = 0; i < nargs; ++i)

  {

    int     argsize;

    int16   aformat;

    argsize = pq_getmsgint(msgBuf, 4);

    if (argsize == -1)

    {

      fcinfo->args[i].isnull = true;

    }

    else

    {

      fcinfo->args[i].isnull = false;

      if (argsize < 0)

        ereport(ERROR,

            (errcode(ERRCODE_PROTOCOL_VIOLATION),

             errmsg("invalid argument size %d in function call message",

                argsize)));

      /* Reset abuf to empty, and insert raw data into it */

      resetStringInfo(&abuf);

      appendBinaryStringInfo(&abuf,

                   pq_getmsgbytes(msgBuf, argsize),

                   argsize);

    }

    if (numAFormats > 1)

      aformat = aformats[i];

    else if (numAFormats > 0)

      aformat = aformats[0];

    else

      aformat = 0;   /* default = text */

    if (aformat == 0)

    {

      Oid     typinput;

      Oid     typioparam;

      char     *pstring;

      getTypeInputInfo(fip->argtypes[i], &typinput, &typioparam);

      /*

       * Since stringinfo.c keeps a trailing null in place even for

       * binary data, the contents of abuf are a valid C string.  We

       * have to do encoding conversion before calling the typinput

       * routine, though.

       */

      if (argsize == -1)

        pstring = NULL;

      else

        pstring = pg_client_to_server(abuf.data, argsize);

      fcinfo->args[i].value = OidInputFunctionCall(typinput, pstring,

                             typioparam, -1);

      /* Free result of encoding conversion, if any */

      if (pstring && pstring != abuf.data)

        pfree(pstring);

    }

    else if (aformat == 1)

    {

      Oid     typreceive;

      Oid     typioparam;

      StringInfo  bufptr;

      /* Call the argument type's binary input converter */

      getTypeBinaryInputInfo(fip->argtypes[i], &typreceive, &typioparam);

      if (argsize == -1)

        bufptr = NULL;

      else

        bufptr = &abuf;

      fcinfo->args[i].value = OidReceiveFunctionCall(typreceive, bufptr,

                               typioparam, -1);

      /* Trouble if it didn't eat the whole buffer */

      if (argsize != -1 && abuf.cursor != abuf.len)

        ereport(ERROR,

            (errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),

             errmsg("incorrect binary data format in function argument %d",

                i + 1)));

    }

    else

      ereport(ERROR,

          (errcode(ERRCODE_INVALID_PARAMETER_VALUE),

           errmsg("unsupported format code: %d", aformat)));

  }

  /* Return result format code */

  return (int16) pq_getmsgint(msgBuf, 2);

}