help_config.c

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/*-------------------------------------------------------------------------
 * help_config.c
 *
 * Displays available options under grand unified configuration scheme
 *
 * Options whose flag bits are set to GUC_NO_SHOW_ALL, GUC_NOT_IN_SAMPLE,
 * or GUC_DISALLOW_IN_FILE are not displayed, unless the user specifically
 * requests that variable by name
 *
 * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *    src/backend/utils/misc/help_config.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"
 
#include <limits.h>
#include <unistd.h>
 
#include "utils/guc_tables.h"
#include "utils/help_config.h"
 
 
/*
 * This union allows us to mix the numerous different types of structs
 * that we are organizing.
 */
typedef union
{
    struct config_generic generic;
    struct config_bool _bool;
    struct config_real real;
    struct config_int integer;
    struct config_string string;
    struct config_enum _enum;
} mixedStruct;
 
 
static void printMixedStruct(mixedStruct *structToPrint);
static bool displayStruct(mixedStruct *structToDisplay);
 
 
void
GucInfoMain(void)
{
    struct config_generic **guc_vars;
    int         numOpts,
                i;
 
    /* Initialize the GUC hash table */
    build_guc_variables();
 
    guc_vars = get_guc_variables(&numOpts);
 
    for (i = 0; i < numOpts; i++)
    {
        mixedStruct *var = (mixedStruct *) guc_vars[i];
 
        if (displayStruct(var))
            printMixedStruct(var);
    }
 
    exit(0);
}
 
 
/*
 * This function will return true if the struct passed to it
 * should be displayed to the user.
 */
static bool
displayStruct(mixedStruct *structToDisplay)
{
    return !(structToDisplay->generic.flags & (GUC_NO_SHOW_ALL |
                                               GUC_NOT_IN_SAMPLE |
                                               GUC_DISALLOW_IN_FILE));
}
 
 
/*
 * This function prints out the generic struct passed to it. It will print out
 * a different format, depending on what the user wants to see.
 */
static void
printMixedStruct(mixedStruct *structToPrint)
{
    printf("%s\t%s\t%s\t",
           structToPrint->generic.name,
           GucContext_Names[structToPrint->generic.context],
           _(config_group_names[structToPrint->generic.group]));
 
    switch (structToPrint->generic.vartype)
    {
 
        case PGC_BOOL:
            printf("BOOLEAN\t%s\t\t\t",
                   (structToPrint->_bool.reset_val == 0) ?
                   "FALSE" : "TRUE");
            break;
 
        case PGC_INT:
            printf("INTEGER\t%d\t%d\t%d\t",
                   structToPrint->integer.reset_val,
                   structToPrint->integer.min,
                   structToPrint->integer.max);
            break;
 
        case PGC_REAL:
            printf("REAL\t%g\t%g\t%g\t",
                   structToPrint->real.reset_val,
                   structToPrint->real.min,
                   structToPrint->real.max);
            break;
 
        case PGC_STRING:
            printf("STRING\t%s\t\t\t",
                   structToPrint->string.boot_val ? structToPrint->string.boot_val : "");
            break;
 
        case PGC_ENUM:
            printf("ENUM\t%s\t\t\t",
                   config_enum_lookup_by_value(&structToPrint->_enum,
                                               structToPrint->_enum.boot_val));
            break;
 
        default:
            write_stderr("internal error: unrecognized run-time parameter type\n");
            break;
    }
 
    printf("%s\t%s\n",
           (structToPrint->generic.short_desc == NULL) ? "" : _(structToPrint->generic.short_desc),
           (structToPrint->generic.long_desc == NULL) ? "" : _(structToPrint->generic.long_desc));
}