pseudotypes.c

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/*-------------------------------------------------------------------------
 *
 * pseudotypes.c
 *    Functions for the system pseudo-types.
 *
 * A pseudo-type isn't really a type and never has any operations, but
 * we do need to supply input and output functions to satisfy the links
 * in the pseudo-type's entry in pg_type.  In most cases the functions
 * just throw an error if invoked.  (XXX the error messages here cover
 * the most common case, but might be confusing in some contexts.  Can
 * we do better?)
 *
 *
 * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/utils/adt/pseudotypes.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "libpq/pqformat.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/rangetypes.h"


/*
 * cstring_in       - input routine for pseudo-type CSTRING.
 *
 * We might as well allow this to support constructs like "foo_in('blah')".
 */
Datum
cstring_in(PG_FUNCTION_ARGS)
{
    char       *str = PG_GETARG_CSTRING(0);

    PG_RETURN_CSTRING(pstrdup(str));
}

/*
 * cstring_out      - output routine for pseudo-type CSTRING.
 *
 * We allow this mainly so that "SELECT some_output_function(...)" does
 * what the user will expect.
 */
Datum
cstring_out(PG_FUNCTION_ARGS)
{
    char       *str = PG_GETARG_CSTRING(0);

    PG_RETURN_CSTRING(pstrdup(str));
}

/*
 * cstring_recv     - binary input routine for pseudo-type CSTRING.
 */
Datum
cstring_recv(PG_FUNCTION_ARGS)
{
    StringInfo  buf = (StringInfo) PG_GETARG_POINTER(0);
    char       *str;
    int         nbytes;

    str = pq_getmsgtext(buf, buf->len - buf->cursor, &nbytes);
    PG_RETURN_CSTRING(str);
}

/*
 * cstring_send     - binary output routine for pseudo-type CSTRING.
 */
Datum
cstring_send(PG_FUNCTION_ARGS)
{
    char       *str = PG_GETARG_CSTRING(0);
    StringInfoData buf;

    pq_begintypsend(&buf);
    pq_sendtext(&buf, str, strlen(str));
    PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}

/*
 * anyarray_in      - input routine for pseudo-type ANYARRAY.
 */
Datum
anyarray_in(PG_FUNCTION_ARGS)
{
    ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("cannot accept a value of type %s", "anyarray")));

    PG_RETURN_VOID();           /* keep compiler quiet */
}

/*
 * anyarray_out     - output routine for pseudo-type ANYARRAY.
 *
 * We may as well allow this, since array_out will in fact work.
 */
Datum
anyarray_out(PG_FUNCTION_ARGS)
{
    return array_out(fcinfo);
}

/*
 * anyarray_recv        - binary input routine for pseudo-type ANYARRAY.
 *
 * XXX this could actually be made to work, since the incoming array
 * data will contain the element type OID.  Need to think through
 * type-safety issues before allowing it, however.
 */
Datum
anyarray_recv(PG_FUNCTION_ARGS)
{
    ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("cannot accept a value of type %s", "anyarray")));

    PG_RETURN_VOID();           /* keep compiler quiet */
}

/*
 * anyarray_send        - binary output routine for pseudo-type ANYARRAY.
 *
 * We may as well allow this, since array_send will in fact work.
 */
Datum
anyarray_send(PG_FUNCTION_ARGS)
{
    return array_send(fcinfo);
}


/*
 * anyenum_in       - input routine for pseudo-type ANYENUM.
 */
Datum
anyenum_in(PG_FUNCTION_ARGS)
{
    ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("cannot accept a value of type %s", "anyenum")));

    PG_RETURN_VOID();           /* keep compiler quiet */
}

/*
 * anyenum_out      - output routine for pseudo-type ANYENUM.
 *
 * We may as well allow this, since enum_out will in fact work.
 */
Datum
anyenum_out(PG_FUNCTION_ARGS)
{
    return enum_out(fcinfo);
}

/*
 * anyrange_in      - input routine for pseudo-type ANYRANGE.
 */
Datum
anyrange_in(PG_FUNCTION_ARGS)
{
    ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("cannot accept a value of type %s", "anyrange")));

    PG_RETURN_VOID();           /* keep compiler quiet */
}

/*
 * anyrange_out     - output routine for pseudo-type ANYRANGE.
 *
 * We may as well allow this, since range_out will in fact work.
 */
Datum
anyrange_out(PG_FUNCTION_ARGS)
{
    return range_out(fcinfo);
}

/*
 * void_in      - input routine for pseudo-type VOID.
 *
 * We allow this so that PL functions can return VOID without any special
 * hack in the PL handler.  Whatever value the PL thinks it's returning
 * will just be ignored.
 */
Datum
void_in(PG_FUNCTION_ARGS)
{
    PG_RETURN_VOID();           /* you were expecting something different? */
}

/*
 * void_out     - output routine for pseudo-type VOID.
 *
 * We allow this so that "SELECT function_returning_void(...)" works.
 */
Datum
void_out(PG_FUNCTION_ARGS)
{
    PG_RETURN_CSTRING(pstrdup(""));
}

/*
 * void_recv    - binary input routine for pseudo-type VOID.
 *
 * Note that since we consume no bytes, an attempt to send anything but
 * an empty string will result in an "invalid message format" error.
 */
Datum
void_recv(PG_FUNCTION_ARGS)
{
    PG_RETURN_VOID();
}

/*
 * void_send    - binary output routine for pseudo-type VOID.
 *
 * We allow this so that "SELECT function_returning_void(...)" works
 * even when binary output is requested.
 */
Datum
void_send(PG_FUNCTION_ARGS)
{
    StringInfoData buf;

    /* send an empty string */
    pq_begintypsend(&buf);
    PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}

/*
 * shell_in     - input routine for "shell" types (those not yet filled in).
 */
Datum
shell_in(PG_FUNCTION_ARGS)
{
    ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("cannot accept a value of a shell type")));

    PG_RETURN_VOID();           /* keep compiler quiet */
}

/*
 * shell_out        - output routine for "shell" types.
 */
Datum
shell_out(PG_FUNCTION_ARGS)
{
    ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("cannot display a value of a shell type")));

    PG_RETURN_VOID();           /* keep compiler quiet */
}


/*
 * pg_node_tree_in      - input routine for type PG_NODE_TREE.
 *
 * pg_node_tree isn't really a pseudotype --- it's real enough to be a table
 * column --- but it presently has no operations of its own, and disallows
 * input too, so its I/O functions seem to fit here as much as anywhere.
 */
Datum
pg_node_tree_in(PG_FUNCTION_ARGS)
{
    /*
     * We disallow input of pg_node_tree values because the SQL functions that
     * operate on the type are not secure against malformed input.
     */
    ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("cannot accept a value of type %s", "pg_node_tree")));

    PG_RETURN_VOID();           /* keep compiler quiet */
}


/*
 * pg_node_tree_out     - output routine for type PG_NODE_TREE.
 *
 * The internal representation is the same as TEXT, so just pass it off.
 */
Datum
pg_node_tree_out(PG_FUNCTION_ARGS)
{
    return textout(fcinfo);
}

/*
 * pg_node_tree_recv        - binary input routine for type PG_NODE_TREE.
 */
Datum
pg_node_tree_recv(PG_FUNCTION_ARGS)
{
    ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("cannot accept a value of type %s", "pg_node_tree")));

    PG_RETURN_VOID();           /* keep compiler quiet */
}

/*
 * pg_node_tree_send        - binary output routine for type PG_NODE_TREE.
 */
Datum
pg_node_tree_send(PG_FUNCTION_ARGS)
{
    return textsend(fcinfo);
}

/*
 * pg_ddl_command_in    - input routine for type PG_DDL_COMMAND.
 *
 * Like pg_node_tree, pg_ddl_command isn't really a pseudotype; it's here for
 * the same reasons as that one.
 */
Datum
pg_ddl_command_in(PG_FUNCTION_ARGS)
{
    /*
     * Disallow input of pg_ddl_command value.
     */
    ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("cannot accept a value of type %s", "pg_ddl_command")));

    PG_RETURN_VOID();           /* keep compiler quiet */
}

/*
 * pg_ddl_command_out       - output routine for type PG_DDL_COMMAND.
 *
 * We don't have any good way to output this type directly, so punt.
 */
Datum
pg_ddl_command_out(PG_FUNCTION_ARGS)
{
    ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("cannot output a value of type %s", "pg_ddl_command")));

    PG_RETURN_VOID();
}

/*
 * pg_ddl_command_recv      - binary input routine for type PG_DDL_COMMAND.
 */
Datum
pg_ddl_command_recv(PG_FUNCTION_ARGS)
{
    ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("cannot accept a value of type %s", "pg_ddl_command")));

    PG_RETURN_VOID();
}

/*
 * pg_ddl_command_send      - binary output routine for type PG_DDL_COMMAND.
 */
Datum
pg_ddl_command_send(PG_FUNCTION_ARGS)
{
    ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("cannot output a value of type %s", "pg_ddl_command")));

    PG_RETURN_VOID();
}


/*
 * Generate input and output functions for a pseudotype that will reject all
 * input and output attempts.
 */
#define PSEUDOTYPE_DUMMY_IO_FUNCS(typname) \
\
Datum \
typname##_in(PG_FUNCTION_ARGS) \
{ \
    ereport(ERROR, \
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), \
             errmsg("cannot accept a value of type %s", #typname))); \
\
    PG_RETURN_VOID();           /* keep compiler quiet */ \
} \
\
Datum \
typname##_out(PG_FUNCTION_ARGS) \
{ \
    ereport(ERROR, \
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), \
             errmsg("cannot display a value of type %s", #typname))); \
\
    PG_RETURN_VOID();           /* keep compiler quiet */ \
} \
\
extern int no_such_variable

PSEUDOTYPE_DUMMY_IO_FUNCS(any);
PSEUDOTYPE_DUMMY_IO_FUNCS(trigger);
PSEUDOTYPE_DUMMY_IO_FUNCS(event_trigger);
PSEUDOTYPE_DUMMY_IO_FUNCS(language_handler);
PSEUDOTYPE_DUMMY_IO_FUNCS(fdw_handler);
PSEUDOTYPE_DUMMY_IO_FUNCS(index_am_handler);
PSEUDOTYPE_DUMMY_IO_FUNCS(tsm_handler);
PSEUDOTYPE_DUMMY_IO_FUNCS(internal);
PSEUDOTYPE_DUMMY_IO_FUNCS(opaque);
PSEUDOTYPE_DUMMY_IO_FUNCS(anyelement);
PSEUDOTYPE_DUMMY_IO_FUNCS(anynonarray);
PSEUDOTYPE_DUMMY_IO_FUNCS(table_am_handler);