/src/postgres/src/backend/nodes/readfuncs.c

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/*-------------------------------------------------------------------------
 *
 * readfuncs.c
 *    Reader functions for Postgres tree nodes.
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/nodes/readfuncs.c
 *
 * NOTES
 *    Parse location fields are written out by outfuncs.c, but only for
 *    debugging use.  When reading a location field, we normally discard
 *    the stored value and set the location field to -1 (ie, "unknown").
 *    This is because nodes coming from a stored rule should not be thought
 *    to have a known location in the current query's text.
 *
 *    However, if restore_location_fields is true, we do restore location
 *    fields from the string.  This is currently intended only for use by the
 *    debug_write_read_parse_plan_trees test code, which doesn't want to cause
 *    any change in the node contents.
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include <math.h>

#include "miscadmin.h"
#include "nodes/bitmapset.h"
#include "nodes/readfuncs.h"


/*
 * Macros to simplify reading of different kinds of fields.  Use these
 * wherever possible to reduce the chance for silly typos.  Note that these
 * hard-wire conventions about the names of the local variables in a Read
 * routine.
 */

/* Macros for declaring appropriate local variables */

/* A few guys need only local_node */
#define READ_LOCALS_NO_FIELDS(nodeTypeName) \
  nodeTypeName *local_node = makeNode(nodeTypeName)

/* And a few guys need only the pg_strtok support fields */
#define READ_TEMP_LOCALS()  \
  const char *token;    \
  int     length

/* ... but most need both */
#define READ_LOCALS(nodeTypeName)     \
  READ_LOCALS_NO_FIELDS(nodeTypeName); \
  READ_TEMP_LOCALS()

/* Read an integer field (anything written as ":fldname %d") */
#define READ_INT_FIELD(fldname) \
  token = pg_strtok(&length);   /* skip :fldname */ \
  token = pg_strtok(&length);   /* get field value */ \
  local_node->fldname = atoi(token)

/* Read an unsigned integer field (anything written as ":fldname %u") */
#define READ_UINT_FIELD(fldname) \
  token = pg_strtok(&length);   /* skip :fldname */ \
  token = pg_strtok(&length);   /* get field value */ \
  local_node->fldname = atoui(token)

/* Read a signed integer field (anything written using INT64_FORMAT) */
#define READ_INT64_FIELD(fldname) \
  token = pg_strtok(&length); /* skip :fldname */ \
  token = pg_strtok(&length); /* get field value */ \
  local_node->fldname = strtoi64(token, NULL, 10)

/* Read an unsigned integer field (anything written using UINT64_FORMAT) */
#define READ_UINT64_FIELD(fldname) \
  token = pg_strtok(&length);   /* skip :fldname */ \
  token = pg_strtok(&length);   /* get field value */ \
  local_node->fldname = strtou64(token, NULL, 10)

/* Read a long integer field (anything written as ":fldname %ld") */
#define READ_LONG_FIELD(fldname) \
  token = pg_strtok(&length);   /* skip :fldname */ \
  token = pg_strtok(&length);   /* get field value */ \
  local_node->fldname = atol(token)

/* Read an OID field (don't hard-wire assumption that OID is same as uint) */
#define READ_OID_FIELD(fldname) \
  token = pg_strtok(&length);   /* skip :fldname */ \
  token = pg_strtok(&length);   /* get field value */ \
  local_node->fldname = atooid(token)

/* Read a char field (ie, one ascii character) */
#define READ_CHAR_FIELD(fldname) \
  token = pg_strtok(&length);   /* skip :fldname */ \
  token = pg_strtok(&length);   /* get field value */ \
  /* avoid overhead of calling debackslash() for one char */ \
  local_node->fldname = (length == 0) ? '\0' : (token[0] == '\\' ? token[1] : token[0])

/* Read an enumerated-type field that was written as an integer code */
#define READ_ENUM_FIELD(fldname, enumtype) \
  token = pg_strtok(&length);   /* skip :fldname */ \
  token = pg_strtok(&length);   /* get field value */ \
  local_node->fldname = (enumtype) atoi(token)

/* Read a float field */
#define READ_FLOAT_FIELD(fldname) \
  token = pg_strtok(&length);   /* skip :fldname */ \
  token = pg_strtok(&length);   /* get field value */ \
  local_node->fldname = atof(token)

/* Read a boolean field */
#define READ_BOOL_FIELD(fldname) \
  token = pg_strtok(&length);   /* skip :fldname */ \
  token = pg_strtok(&length);   /* get field value */ \
  local_node->fldname = strtobool(token)

/* Read a character-string field */
#define READ_STRING_FIELD(fldname) \
  token = pg_strtok(&length);   /* skip :fldname */ \
  token = pg_strtok(&length);   /* get field value */ \
  local_node->fldname = nullable_string(token, length)

/* Read a parse location field (and possibly throw away the value) */
#ifdef DEBUG_NODE_TESTS_ENABLED
#define READ_LOCATION_FIELD(fldname) \
  token = pg_strtok(&length);   /* skip :fldname */ \
  token = pg_strtok(&length);   /* get field value */ \
  local_node->fldname = restore_location_fields ? atoi(token) : -1
#else
#define READ_LOCATION_FIELD(fldname) \
  token = pg_strtok(&length);   /* skip :fldname */ \
  token = pg_strtok(&length);   /* get field value */ \
  (void) token;       /* in case not used elsewhere */ \
  local_node->fldname = -1  /* set field to "unknown" */
#endif

/* Read a Node field */
#define READ_NODE_FIELD(fldname) \
  token = pg_strtok(&length);   /* skip :fldname */ \
  (void) token;       /* in case not used elsewhere */ \
  local_node->fldname = nodeRead(NULL, 0)

/* Read a bitmapset field */
#define READ_BITMAPSET_FIELD(fldname) \
  token = pg_strtok(&length);   /* skip :fldname */ \
  (void) token;       /* in case not used elsewhere */ \
  local_node->fldname = _readBitmapset()

/* Read an attribute number array */
#define READ_ATTRNUMBER_ARRAY(fldname, len) \
  token = pg_strtok(&length);   /* skip :fldname */ \
  local_node->fldname = readAttrNumberCols(len)

/* Read an oid array */
#define READ_OID_ARRAY(fldname, len) \
  token = pg_strtok(&length);   /* skip :fldname */ \
  local_node->fldname = readOidCols(len)

/* Read an int array */
#define READ_INT_ARRAY(fldname, len) \
  token = pg_strtok(&length);   /* skip :fldname */ \
  local_node->fldname = readIntCols(len)

/* Read a bool array */
#define READ_BOOL_ARRAY(fldname, len) \
  token = pg_strtok(&length);   /* skip :fldname */ \
  local_node->fldname = readBoolCols(len)

/* Routine exit */
#define READ_DONE() \
  return local_node


/*
 * NOTE: use atoi() to read values written with %d, or atoui() to read
 * values written with %u in outfuncs.c.  An exception is OID values,
 * for which use atooid().  (As of 7.1, outfuncs.c writes OIDs as %u,
 * but this will probably change in the future.)
 */
#define atoui(x)  ((unsigned int) strtoul((x), NULL, 10))

#define strtobool(x)  ((*(x) == 't') ? true : false)

static char *
nullable_string(const char *token, int length)
{
  /* outToken emits <> for NULL, and pg_strtok makes that an empty string */
  if (length == 0)
    return NULL;
  /* outToken emits "" for empty string */
  if (length == 2 && token[0] == '"' && token[1] == '"')
    return pstrdup("");
  /* otherwise, we must remove protective backslashes added by outToken */
  return debackslash(token, length);
}


/*
 * _readBitmapset
 *
 * Note: this code is used in contexts where we know that a Bitmapset
 * is expected.  There is equivalent code in nodeRead() that can read a
 * Bitmapset when we come across one in other contexts.
 */
static Bitmapset *
_readBitmapset(void)
{
  Bitmapset  *result = NULL;

  READ_TEMP_LOCALS();

  token = pg_strtok(&length);
  if (token == NULL)
    elog(ERROR, "incomplete Bitmapset structure");
  if (length != 1 || token[0] != '(')
    elog(ERROR, "unrecognized token: \"%.*s\"", length, token);

  token = pg_strtok(&length);
  if (token == NULL)
    elog(ERROR, "incomplete Bitmapset structure");
  if (length != 1 || token[0] != 'b')
    elog(ERROR, "unrecognized token: \"%.*s\"", length, token);

  for (;;)
  {
    int     val;
    char     *endptr;

    token = pg_strtok(&length);
    if (token == NULL)
      elog(ERROR, "unterminated Bitmapset structure");
    if (length == 1 && token[0] == ')')
      break;
    val = (int) strtol(token, &endptr, 10);
    if (endptr != token + length)
      elog(ERROR, "unrecognized integer: \"%.*s\"", length, token);
    result = bms_add_member(result, val);
  }

  return result;
}

/*
 * We export this function for use by extensions that define extensible nodes.
 * That's somewhat historical, though, because calling nodeRead() will work.
 */
Bitmapset *
readBitmapset(void)
{
  return _readBitmapset();
}

#include "readfuncs.funcs.c"


/*
 * Support functions for nodes with custom_read_write attribute or
 * special_read_write attribute
 */

static Const *
_readConst(void)
{
  READ_LOCALS(Const);

  READ_OID_FIELD(consttype);
  READ_INT_FIELD(consttypmod);
  READ_OID_FIELD(constcollid);
  READ_INT_FIELD(constlen);
  READ_BOOL_FIELD(constbyval);
  READ_BOOL_FIELD(constisnull);
  READ_LOCATION_FIELD(location);

  token = pg_strtok(&length); /* skip :constvalue */
  if (local_node->constisnull)
    token = pg_strtok(&length); /* skip "<>" */
  else
    local_node->constvalue = readDatum(local_node->constbyval);

  READ_DONE();
}

static BoolExpr *
_readBoolExpr(void)
{
  READ_LOCALS(BoolExpr);

  /* do-it-yourself enum representation */
  token = pg_strtok(&length); /* skip :boolop */
  token = pg_strtok(&length); /* get field value */
  if (length == 3 && strncmp(token, "and", 3) == 0)
    local_node->boolop = AND_EXPR;
  else if (length == 2 && strncmp(token, "or", 2) == 0)
    local_node->boolop = OR_EXPR;
  else if (length == 3 && strncmp(token, "not", 3) == 0)
    local_node->boolop = NOT_EXPR;
  else
    elog(ERROR, "unrecognized boolop \"%.*s\"", length, token);

  READ_NODE_FIELD(args);
  READ_LOCATION_FIELD(location);

  READ_DONE();
}

static A_Const *
_readA_Const(void)
{
  READ_LOCALS(A_Const);

  /* We expect either NULL or :val here */
  token = pg_strtok(&length);
  if (length == 4 && strncmp(token, "NULL", 4) == 0)
    local_node->isnull = true;
  else
  {
    union ValUnion *tmp = nodeRead(NULL, 0);

    /* To forestall valgrind complaints, copy only the valid data */
    switch (nodeTag(tmp))
    {
      case T_Integer:
        memcpy(&local_node->val, tmp, sizeof(Integer));
        break;
      case T_Float:
        memcpy(&local_node->val, tmp, sizeof(Float));
        break;
      case T_Boolean:
        memcpy(&local_node->val, tmp, sizeof(Boolean));
        break;
      case T_String:
        memcpy(&local_node->val, tmp, sizeof(String));
        break;
      case T_BitString:
        memcpy(&local_node->val, tmp, sizeof(BitString));
        break;
      default:
        elog(ERROR, "unrecognized node type: %d",
           (int) nodeTag(tmp));
        break;
    }
  }

  READ_LOCATION_FIELD(location);

  READ_DONE();
}

static RangeTblEntry *
_readRangeTblEntry(void)
{
  READ_LOCALS(RangeTblEntry);

  READ_NODE_FIELD(alias);
  READ_NODE_FIELD(eref);
  READ_ENUM_FIELD(rtekind, RTEKind);

  switch (local_node->rtekind)
  {
    case RTE_RELATION:
      READ_OID_FIELD(relid);
      READ_BOOL_FIELD(inh);
      READ_CHAR_FIELD(relkind);
      READ_INT_FIELD(rellockmode);
      READ_UINT_FIELD(perminfoindex);
      READ_NODE_FIELD(tablesample);
      break;
    case RTE_SUBQUERY:
      READ_NODE_FIELD(subquery);
      READ_BOOL_FIELD(security_barrier);
      /* we re-use these RELATION fields, too: */
      READ_OID_FIELD(relid);
      READ_BOOL_FIELD(inh);
      READ_CHAR_FIELD(relkind);
      READ_INT_FIELD(rellockmode);
      READ_UINT_FIELD(perminfoindex);
      break;
    case RTE_JOIN:
      READ_ENUM_FIELD(jointype, JoinType);
      READ_INT_FIELD(joinmergedcols);
      READ_NODE_FIELD(joinaliasvars);
      READ_NODE_FIELD(joinleftcols);
      READ_NODE_FIELD(joinrightcols);
      READ_NODE_FIELD(join_using_alias);
      break;
    case RTE_FUNCTION:
      READ_NODE_FIELD(functions);
      READ_BOOL_FIELD(funcordinality);
      break;
    case RTE_TABLEFUNC:
      READ_NODE_FIELD(tablefunc);
      /* The RTE must have a copy of the column type info, if any */
      if (local_node->tablefunc)
      {
        TableFunc  *tf = local_node->tablefunc;

        local_node->coltypes = tf->coltypes;
        local_node->coltypmods = tf->coltypmods;
        local_node->colcollations = tf->colcollations;
      }
      break;
    case RTE_VALUES:
      READ_NODE_FIELD(values_lists);
      READ_NODE_FIELD(coltypes);
      READ_NODE_FIELD(coltypmods);
      READ_NODE_FIELD(colcollations);
      break;
    case RTE_CTE:
      READ_STRING_FIELD(ctename);
      READ_UINT_FIELD(ctelevelsup);
      READ_BOOL_FIELD(self_reference);
      READ_NODE_FIELD(coltypes);
      READ_NODE_FIELD(coltypmods);
      READ_NODE_FIELD(colcollations);
      break;
    case RTE_NAMEDTUPLESTORE:
      READ_STRING_FIELD(enrname);
      READ_FLOAT_FIELD(enrtuples);
      READ_NODE_FIELD(coltypes);
      READ_NODE_FIELD(coltypmods);
      READ_NODE_FIELD(colcollations);
      /* we re-use these RELATION fields, too: */
      READ_OID_FIELD(relid);
      break;
    case RTE_RESULT:
      /* no extra fields */
      break;
    case RTE_GROUP:
      READ_NODE_FIELD(groupexprs);
      break;
    default:
      elog(ERROR, "unrecognized RTE kind: %d",
         (int) local_node->rtekind);
      break;
  }

  READ_BOOL_FIELD(lateral);
  READ_BOOL_FIELD(inFromCl);
  READ_NODE_FIELD(securityQuals);

  READ_DONE();
}

static A_Expr *
_readA_Expr(void)
{
  READ_LOCALS(A_Expr);

  token = pg_strtok(&length);

  if (length == 3 && strncmp(token, "ANY", 3) == 0)
  {
    local_node->kind = AEXPR_OP_ANY;
    READ_NODE_FIELD(name);
  }
  else if (length == 3 && strncmp(token, "ALL", 3) == 0)
  {
    local_node->kind = AEXPR_OP_ALL;
    READ_NODE_FIELD(name);
  }
  else if (length == 8 && strncmp(token, "DISTINCT", 8) == 0)
  {
    local_node->kind = AEXPR_DISTINCT;
    READ_NODE_FIELD(name);
  }
  else if (length == 12 && strncmp(token, "NOT_DISTINCT", 12) == 0)
  {
    local_node->kind = AEXPR_NOT_DISTINCT;
    READ_NODE_FIELD(name);
  }
  else if (length == 6 && strncmp(token, "NULLIF", 6) == 0)
  {
    local_node->kind = AEXPR_NULLIF;
    READ_NODE_FIELD(name);
  }
  else if (length == 2 && strncmp(token, "IN", 2) == 0)
  {
    local_node->kind = AEXPR_IN;
    READ_NODE_FIELD(name);
  }
  else if (length == 4 && strncmp(token, "LIKE", 4) == 0)
  {
    local_node->kind = AEXPR_LIKE;
    READ_NODE_FIELD(name);
  }
  else if (length == 5 && strncmp(token, "ILIKE", 5) == 0)
  {
    local_node->kind = AEXPR_ILIKE;
    READ_NODE_FIELD(name);
  }
  else if (length == 7 && strncmp(token, "SIMILAR", 7) == 0)
  {
    local_node->kind = AEXPR_SIMILAR;
    READ_NODE_FIELD(name);
  }
  else if (length == 7 && strncmp(token, "BETWEEN", 7) == 0)
  {
    local_node->kind = AEXPR_BETWEEN;
    READ_NODE_FIELD(name);
  }
  else if (length == 11 && strncmp(token, "NOT_BETWEEN", 11) == 0)
  {
    local_node->kind = AEXPR_NOT_BETWEEN;
    READ_NODE_FIELD(name);
  }
  else if (length == 11 && strncmp(token, "BETWEEN_SYM", 11) == 0)
  {
    local_node->kind = AEXPR_BETWEEN_SYM;
    READ_NODE_FIELD(name);
  }
  else if (length == 15 && strncmp(token, "NOT_BETWEEN_SYM", 15) == 0)
  {
    local_node->kind = AEXPR_NOT_BETWEEN_SYM;
    READ_NODE_FIELD(name);
  }
  else if (length == 5 && strncmp(token, ":name", 5) == 0)
  {
    local_node->kind = AEXPR_OP;
    local_node->name = nodeRead(NULL, 0);
  }
  else
    elog(ERROR, "unrecognized A_Expr kind: \"%.*s\"", length, token);

  READ_NODE_FIELD(lexpr);
  READ_NODE_FIELD(rexpr);
  READ_LOCATION_FIELD(rexpr_list_start);
  READ_LOCATION_FIELD(rexpr_list_end);
  READ_LOCATION_FIELD(location);

  READ_DONE();
}

static ExtensibleNode *
_readExtensibleNode(void)
{
  const ExtensibleNodeMethods *methods;
  ExtensibleNode *local_node;
  const char *extnodename;

  READ_TEMP_LOCALS();

  token = pg_strtok(&length); /* skip :extnodename */
  token = pg_strtok(&length); /* get extnodename */

  extnodename = nullable_string(token, length);
  if (!extnodename)
    elog(ERROR, "extnodename has to be supplied");
  methods = GetExtensibleNodeMethods(extnodename, false);

  local_node = (ExtensibleNode *) newNode(methods->node_size,
                      T_ExtensibleNode);
  local_node->extnodename = extnodename;

  /* deserialize the private fields */
  methods->nodeRead(local_node);

  READ_DONE();
}


/*
 * parseNodeString
 *
 * Given a character string representing a node tree, parseNodeString creates
 * the internal node structure.
 *
 * The string to be read must already have been loaded into pg_strtok().
 */
Node *
parseNodeString(void)
{
  READ_TEMP_LOCALS();

  /* Guard against stack overflow due to overly complex expressions */
  check_stack_depth();

  token = pg_strtok(&length);

#define MATCH(tokname, namelen) \
  (length == namelen && memcmp(token, tokname, namelen) == 0)

#include "readfuncs.switch.c"

  elog(ERROR, "badly formatted node string \"%.32s\"...", token);
  return NULL;       /* keep compiler quiet */
}


/*
 * readDatum
 *
 * Given a string representation of a constant, recreate the appropriate
 * Datum.  The string representation embeds length info, but not byValue,
 * so we must be told that.
 */
Datum
readDatum(bool typbyval)
{
  Size    length,
        i;
  int     tokenLength;
  const char *token;
  Datum   res;
  char     *s;

  /*
   * read the actual length of the value
   */
  token = pg_strtok(&tokenLength);
  length = atoui(token);

  token = pg_strtok(&tokenLength);  /* read the '[' */
  if (token == NULL || token[0] != '[')
    elog(ERROR, "expected \"[\" to start datum, but got \"%s\"; length = %zu",
       token ? token : "[NULL]", length);

  if (typbyval)
  {
    if (length > (Size) sizeof(Datum))
      elog(ERROR, "byval datum but length = %zu", length);
    res = (Datum) 0;
    s = (char *) (&res);
    for (i = 0; i < (Size) sizeof(Datum); i++)
    {
      token = pg_strtok(&tokenLength);
      s[i] = (char) atoi(token);
    }
  }
  else if (length <= 0)
    res = (Datum) NULL;
  else
  {
    s = (char *) palloc(length);
    for (i = 0; i < length; i++)
    {
      token = pg_strtok(&tokenLength);
      s[i] = (char) atoi(token);
    }
    res = PointerGetDatum(s);
  }

  token = pg_strtok(&tokenLength);  /* read the ']' */
  if (token == NULL || token[0] != ']')
    elog(ERROR, "expected \"]\" to end datum, but got \"%s\"; length = %zu",
       token ? token : "[NULL]", length);

  return res;
}

/*
 * common implementation for scalar-array-reading functions
 *
 * The data format is either "<>" for a NULL pointer (in which case numCols
 * is ignored) or "(item item item)" where the number of items must equal
 * numCols.  The convfunc must be okay with stopping at whitespace or a
 * right parenthesis, since pg_strtok won't null-terminate the token.
 */
#define READ_SCALAR_ARRAY(fnname, datatype, convfunc) \
datatype * \
fnname(int numCols) \
{ \
  datatype   *vals; \
  READ_TEMP_LOCALS(); \
  token = pg_strtok(&length); \
  if (token == NULL) \
    elog(ERROR, "incomplete scalar array"); \
  if (length == 0) \
    return NULL;     /* it was "<>", so return NULL pointer */ \
  if (length != 1 || token[0] != '(') \
    elog(ERROR, "unrecognized token: \"%.*s\"", length, token); \
  vals = (datatype *) palloc(numCols * sizeof(datatype)); \
  for (int i = 0; i < numCols; i++) \
  { \
    token = pg_strtok(&length); \
    if (token == NULL || token[0] == ')') \
      elog(ERROR, "incomplete scalar array"); \
    vals[i] = convfunc(token); \
  } \
  token = pg_strtok(&length); \
  if (token == NULL || length != 1 || token[0] != ')') \
    elog(ERROR, "incomplete scalar array"); \
  return vals; \
}

/*
 * Note: these functions are exported in nodes.h for possible use by
 * extensions, so don't mess too much with their names or API.
 */
READ_SCALAR_ARRAY(readAttrNumberCols, int16, atoi)
READ_SCALAR_ARRAY(readOidCols, Oid, atooid)
/* outfuncs.c has writeIndexCols, but we don't yet need that here */
/* READ_SCALAR_ARRAY(readIndexCols, Index, atoui) */
READ_SCALAR_ARRAY(readIntCols, int, atoi)
READ_SCALAR_ARRAY(readBoolCols, bool, strtobool)

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Created: 2025-07-03 06:49