startup.c

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/*
 * psql - the PostgreSQL interactive terminal
 *
 * Copyright (c) 2000-2021, PostgreSQL Global Development Group
 *
 * src/bin/psql/startup.c
 */
#include "postgres_fe.h"

#ifndef WIN32
#include <unistd.h>
#else                           /* WIN32 */
#include <io.h>
#include <win32.h>
#endif                          /* WIN32 */

#include "command.h"
#include "common.h"
#include "common/logging.h"
#include "common/string.h"
#include "describe.h"
#include "fe_utils/print.h"
#include "getopt_long.h"
#include "help.h"
#include "input.h"
#include "mainloop.h"
#include "settings.h"

/*
 * Global psql options
 */
PsqlSettings pset;

#ifndef WIN32
#define SYSPSQLRC   "psqlrc"
#define PSQLRC      ".psqlrc"
#else
#define SYSPSQLRC   "psqlrc"
#define PSQLRC      "psqlrc.conf"
#endif

/*
 * Structures to pass information between the option parsing routine
 * and the main function
 */
enum _actions
{
    ACT_SINGLE_QUERY,
    ACT_SINGLE_SLASH,
    ACT_FILE
};

typedef struct SimpleActionListCell
{
    struct SimpleActionListCell *next;
    enum _actions action;
    char       *val;
} SimpleActionListCell;

typedef struct SimpleActionList
{
    SimpleActionListCell *head;
    SimpleActionListCell *tail;
} SimpleActionList;

struct adhoc_opts
{
    char       *dbname;
    char       *host;
    char       *port;
    char       *username;
    char       *logfilename;
    bool        no_readline;
    bool        no_psqlrc;
    bool        single_txn;
    bool        list_dbs;
    SimpleActionList actions;
};

static void parse_psql_options(int argc, char *argv[],
                               struct adhoc_opts *options);
static void simple_action_list_append(SimpleActionList *list,
                                      enum _actions action, const char *val);
static void process_psqlrc(char *argv0);
static void process_psqlrc_file(char *filename);
static void showVersion(void);
static void EstablishVariableSpace(void);

#define NOPAGER     0

static void
log_pre_callback(void)
{
    if (pset.queryFout && pset.queryFout != stdout)
        fflush(pset.queryFout);
}

static void
log_locus_callback(const char **filename, uint64 *lineno)
{
    if (pset.inputfile)
    {
        *filename = pset.inputfile;
        *lineno = pset.lineno;
    }
    else
    {
        *filename = NULL;
        *lineno = 0;
    }
}

/*
 *
 * main
 *
 */
int
main(int argc, char *argv[])
{
    struct adhoc_opts options;
    int         successResult;
    char       *password = NULL;
    bool        new_pass;

    pg_logging_init(argv[0]);
    pg_logging_set_pre_callback(log_pre_callback);
    pg_logging_set_locus_callback(log_locus_callback);
    set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("psql"));

    if (argc > 1)
    {
        if ((strcmp(argv[1], "-?") == 0) || (argc == 2 && (strcmp(argv[1], "--help") == 0)))
        {
            usage(NOPAGER);
            exit(EXIT_SUCCESS);
        }
        if (strcmp(argv[1], "--version") == 0 || strcmp(argv[1], "-V") == 0)
        {
            showVersion();
            exit(EXIT_SUCCESS);
        }
    }

    pset.progname = get_progname(argv[0]);

    pset.db = NULL;
    pset.dead_conn = NULL;
    setDecimalLocale();
    pset.encoding = PQenv2encoding();
    pset.queryFout = stdout;
    pset.queryFoutPipe = false;
    pset.copyStream = NULL;
    pset.last_error_result = NULL;
    pset.cur_cmd_source = stdin;
    pset.cur_cmd_interactive = false;

    /* We rely on unmentioned fields of pset.popt to start out 0/false/NULL */
    pset.popt.topt.format = PRINT_ALIGNED;
    pset.popt.topt.border = 1;
    pset.popt.topt.pager = 1;
    pset.popt.topt.pager_min_lines = 0;
    pset.popt.topt.start_table = true;
    pset.popt.topt.stop_table = true;
    pset.popt.topt.default_footer = true;

    pset.popt.topt.csvFieldSep[0] = DEFAULT_CSV_FIELD_SEP;
    pset.popt.topt.csvFieldSep[1] = '\0';

    pset.popt.topt.unicode_border_linestyle = UNICODE_LINESTYLE_SINGLE;
    pset.popt.topt.unicode_column_linestyle = UNICODE_LINESTYLE_SINGLE;
    pset.popt.topt.unicode_header_linestyle = UNICODE_LINESTYLE_SINGLE;

    refresh_utf8format(&(pset.popt.topt));

    /* We must get COLUMNS here before readline() sets it */
    pset.popt.topt.env_columns = getenv("COLUMNS") ? atoi(getenv("COLUMNS")) : 0;

    pset.notty = (!isatty(fileno(stdin)) || !isatty(fileno(stdout)));

    pset.getPassword = TRI_DEFAULT;

    EstablishVariableSpace();

    /* Create variables showing psql version number */
    SetVariable(pset.vars, "VERSION", PG_VERSION_STR);
    SetVariable(pset.vars, "VERSION_NAME", PG_VERSION);
    SetVariable(pset.vars, "VERSION_NUM", CppAsString2(PG_VERSION_NUM));

    /* Initialize variables for last error */
    SetVariable(pset.vars, "LAST_ERROR_MESSAGE", "");
    SetVariable(pset.vars, "LAST_ERROR_SQLSTATE", "00000");

    /* Default values for variables (that don't match the result of \unset) */
    SetVariableBool(pset.vars, "AUTOCOMMIT");
    SetVariable(pset.vars, "PROMPT1", DEFAULT_PROMPT1);
    SetVariable(pset.vars, "PROMPT2", DEFAULT_PROMPT2);
    SetVariable(pset.vars, "PROMPT3", DEFAULT_PROMPT3);

    parse_psql_options(argc, argv, &options);

    /*
     * If no action was specified and we're in non-interactive mode, treat it
     * as if the user had specified "-f -".  This lets single-transaction mode
     * work in this case.
     */
    if (options.actions.head == NULL && pset.notty)
        simple_action_list_append(&options.actions, ACT_FILE, NULL);

    /* Bail out if -1 was specified but will be ignored. */
    if (options.single_txn && options.actions.head == NULL)
    {
        pg_log_fatal("-1 can only be used in non-interactive mode");
        exit(EXIT_FAILURE);
    }

    if (!pset.popt.topt.fieldSep.separator &&
        !pset.popt.topt.fieldSep.separator_zero)
    {
        pset.popt.topt.fieldSep.separator = pg_strdup(DEFAULT_FIELD_SEP);
        pset.popt.topt.fieldSep.separator_zero = false;
    }
    if (!pset.popt.topt.recordSep.separator &&
        !pset.popt.topt.recordSep.separator_zero)
    {
        pset.popt.topt.recordSep.separator = pg_strdup(DEFAULT_RECORD_SEP);
        pset.popt.topt.recordSep.separator_zero = false;
    }

    if (pset.getPassword == TRI_YES)
    {
        /*
         * We can't be sure yet of the username that will be used, so don't
         * offer a potentially wrong one.  Typical uses of this option are
         * noninteractive anyway.
         */
        password = simple_prompt("Password: ", false);
    }

    /* loop until we have a password if requested by backend */
    do
    {
#define PARAMS_ARRAY_SIZE   8
        const char **keywords = pg_malloc(PARAMS_ARRAY_SIZE * sizeof(*keywords));
        const char **values = pg_malloc(PARAMS_ARRAY_SIZE * sizeof(*values));

        keywords[0] = "host";
        values[0] = options.host;
        keywords[1] = "port";
        values[1] = options.port;
        keywords[2] = "user";
        values[2] = options.username;
        keywords[3] = "password";
        values[3] = password;
        keywords[4] = "dbname"; /* see do_connect() */
        values[4] = (options.list_dbs && options.dbname == NULL) ?
            "postgres" : options.dbname;
        keywords[5] = "fallback_application_name";
        values[5] = pset.progname;
        keywords[6] = "client_encoding";
        values[6] = (pset.notty || getenv("PGCLIENTENCODING")) ? NULL : "auto";
        keywords[7] = NULL;
        values[7] = NULL;

        new_pass = false;
        pset.db = PQconnectdbParams(keywords, values, true);
        free(keywords);
        free(values);

        if (PQstatus(pset.db) == CONNECTION_BAD &&
            PQconnectionNeedsPassword(pset.db) &&
            !password &&
            pset.getPassword != TRI_NO)
        {
            /*
             * Before closing the old PGconn, extract the user name that was
             * actually connected with --- it might've come out of a URI or
             * connstring "database name" rather than options.username.
             */
            const char *realusername = PQuser(pset.db);
            char       *password_prompt;

            if (realusername && realusername[0])
                password_prompt = psprintf(_("Password for user %s: "),
                                           realusername);
            else
                password_prompt = pg_strdup(_("Password: "));
            PQfinish(pset.db);

            password = simple_prompt(password_prompt, false);
            free(password_prompt);
            new_pass = true;
        }
    } while (new_pass);

    if (PQstatus(pset.db) == CONNECTION_BAD)
    {
        pg_log_error("%s", PQerrorMessage(pset.db));
        PQfinish(pset.db);
        exit(EXIT_BADCONN);
    }

    psql_setup_cancel_handler();

    PQsetNoticeProcessor(pset.db, NoticeProcessor, NULL);

    SyncVariables();

    if (options.list_dbs)
    {
        int         success;

        if (!options.no_psqlrc)
            process_psqlrc(argv[0]);

        success = listAllDbs(NULL, false);
        PQfinish(pset.db);
        exit(success ? EXIT_SUCCESS : EXIT_FAILURE);
    }

    if (options.logfilename)
    {
        pset.logfile = fopen(options.logfilename, "a");
        if (!pset.logfile)
        {
            pg_log_fatal("could not open log file \"%s\": %m",
                         options.logfilename);
            exit(EXIT_FAILURE);
        }
    }

    if (!options.no_psqlrc)
        process_psqlrc(argv[0]);

    /*
     * If any actions were given by user, process them in the order in which
     * they were specified.  Note single_txn is only effective in this mode.
     */
    if (options.actions.head != NULL)
    {
        PGresult   *res;
        SimpleActionListCell *cell;

        successResult = EXIT_SUCCESS;   /* silence compiler */

        if (options.single_txn)
        {
            if ((res = PSQLexec("BEGIN")) == NULL)
            {
                if (pset.on_error_stop)
                {
                    successResult = EXIT_USER;
                    goto error;
                }
            }
            else
                PQclear(res);
        }

        for (cell = options.actions.head; cell; cell = cell->next)
        {
            if (cell->action == ACT_SINGLE_QUERY)
            {
                pg_logging_config(PG_LOG_FLAG_TERSE);

                if (pset.echo == PSQL_ECHO_ALL)
                    puts(cell->val);

                successResult = SendQuery(cell->val)
                    ? EXIT_SUCCESS : EXIT_FAILURE;
            }
            else if (cell->action == ACT_SINGLE_SLASH)
            {
                PsqlScanState scan_state;
                ConditionalStack cond_stack;

                pg_logging_config(PG_LOG_FLAG_TERSE);

                if (pset.echo == PSQL_ECHO_ALL)
                    puts(cell->val);

                scan_state = psql_scan_create(&psqlscan_callbacks);
                psql_scan_setup(scan_state,
                                cell->val, strlen(cell->val),
                                pset.encoding, standard_strings());
                cond_stack = conditional_stack_create();
                psql_scan_set_passthrough(scan_state, (void *) cond_stack);

                successResult = HandleSlashCmds(scan_state,
                                                cond_stack,
                                                NULL,
                                                NULL) != PSQL_CMD_ERROR
                    ? EXIT_SUCCESS : EXIT_FAILURE;

                psql_scan_destroy(scan_state);
                conditional_stack_destroy(cond_stack);
            }
            else if (cell->action == ACT_FILE)
            {
                successResult = process_file(cell->val, false);
            }
            else
            {
                /* should never come here */
                Assert(false);
            }

            if (successResult != EXIT_SUCCESS && pset.on_error_stop)
                break;
        }

        if (options.single_txn)
        {
            if ((res = PSQLexec("COMMIT")) == NULL)
            {
                if (pset.on_error_stop)
                {
                    successResult = EXIT_USER;
                    goto error;
                }
            }
            else
                PQclear(res);
        }

error:
        ;
    }

    /*
     * or otherwise enter interactive main loop
     */
    else
    {
        pg_logging_config(PG_LOG_FLAG_TERSE);
        connection_warnings(true);
        if (!pset.quiet)
            printf(_("Type \"help\" for help.\n\n"));
        initializeInput(options.no_readline ? 0 : 1);
        successResult = MainLoop(stdin);
    }

    /* clean up */
    if (pset.logfile)
        fclose(pset.logfile);
    if (pset.db)
        PQfinish(pset.db);
    if (pset.dead_conn)
        PQfinish(pset.dead_conn);
    setQFout(NULL);

    return successResult;
}


/*
 * Parse command line options
 */

static void
parse_psql_options(int argc, char *argv[], struct adhoc_opts *options)
{
    static struct option long_options[] =
    {
        {"echo-all", no_argument, NULL, 'a'},
        {"no-align", no_argument, NULL, 'A'},
        {"command", required_argument, NULL, 'c'},
        {"dbname", required_argument, NULL, 'd'},
        {"echo-queries", no_argument, NULL, 'e'},
        {"echo-errors", no_argument, NULL, 'b'},
        {"echo-hidden", no_argument, NULL, 'E'},
        {"file", required_argument, NULL, 'f'},
        {"field-separator", required_argument, NULL, 'F'},
        {"field-separator-zero", no_argument, NULL, 'z'},
        {"host", required_argument, NULL, 'h'},
        {"html", no_argument, NULL, 'H'},
        {"list", no_argument, NULL, 'l'},
        {"log-file", required_argument, NULL, 'L'},
        {"no-readline", no_argument, NULL, 'n'},
        {"single-transaction", no_argument, NULL, '1'},
        {"output", required_argument, NULL, 'o'},
        {"port", required_argument, NULL, 'p'},
        {"pset", required_argument, NULL, 'P'},
        {"quiet", no_argument, NULL, 'q'},
        {"record-separator", required_argument, NULL, 'R'},
        {"record-separator-zero", no_argument, NULL, '0'},
        {"single-step", no_argument, NULL, 's'},
        {"single-line", no_argument, NULL, 'S'},
        {"tuples-only", no_argument, NULL, 't'},
        {"table-attr", required_argument, NULL, 'T'},
        {"username", required_argument, NULL, 'U'},
        {"set", required_argument, NULL, 'v'},
        {"variable", required_argument, NULL, 'v'},
        {"version", no_argument, NULL, 'V'},
        {"no-password", no_argument, NULL, 'w'},
        {"password", no_argument, NULL, 'W'},
        {"expanded", no_argument, NULL, 'x'},
        {"no-psqlrc", no_argument, NULL, 'X'},
        {"help", optional_argument, NULL, 1},
        {"csv", no_argument, NULL, 2},
        {NULL, 0, NULL, 0}
    };

    int         optindex;
    int         c;

    memset(options, 0, sizeof *options);

    while ((c = getopt_long(argc, argv, "aAbc:d:eEf:F:h:HlL:no:p:P:qR:sStT:U:v:VwWxXz?01",
                            long_options, &optindex)) != -1)
    {
        switch (c)
        {
            case 'a':
                SetVariable(pset.vars, "ECHO", "all");
                break;
            case 'A':
                pset.popt.topt.format = PRINT_UNALIGNED;
                break;
            case 'b':
                SetVariable(pset.vars, "ECHO", "errors");
                break;
            case 'c':
                if (optarg[0] == '\\')
                    simple_action_list_append(&options->actions,
                                              ACT_SINGLE_SLASH,
                                              optarg + 1);
                else
                    simple_action_list_append(&options->actions,
                                              ACT_SINGLE_QUERY,
                                              optarg);
                break;
            case 'd':
                options->dbname = pg_strdup(optarg);
                break;
            case 'e':
                SetVariable(pset.vars, "ECHO", "queries");
                break;
            case 'E':
                SetVariableBool(pset.vars, "ECHO_HIDDEN");
                break;
            case 'f':
                simple_action_list_append(&options->actions,
                                          ACT_FILE,
                                          optarg);
                break;
            case 'F':
                pset.popt.topt.fieldSep.separator = pg_strdup(optarg);
                pset.popt.topt.fieldSep.separator_zero = false;
                break;
            case 'h':
                options->host = pg_strdup(optarg);
                break;
            case 'H':
                pset.popt.topt.format = PRINT_HTML;
                break;
            case 'l':
                options->list_dbs = true;
                break;
            case 'L':
                options->logfilename = pg_strdup(optarg);
                break;
            case 'n':
                options->no_readline = true;
                break;
            case 'o':
                if (!setQFout(optarg))
                    exit(EXIT_FAILURE);
                break;
            case 'p':
                options->port = pg_strdup(optarg);
                break;
            case 'P':
                {
                    char       *value;
                    char       *equal_loc;
                    bool        result;

                    value = pg_strdup(optarg);
                    equal_loc = strchr(value, '=');
                    if (!equal_loc)
                        result = do_pset(value, NULL, &pset.popt, true);
                    else
                    {
                        *equal_loc = '\0';
                        result = do_pset(value, equal_loc + 1, &pset.popt, true);
                    }

                    if (!result)
                    {
                        pg_log_fatal("could not set printing parameter \"%s\"", value);
                        exit(EXIT_FAILURE);
                    }

                    free(value);
                    break;
                }
            case 'q':
                SetVariableBool(pset.vars, "QUIET");
                break;
            case 'R':
                pset.popt.topt.recordSep.separator = pg_strdup(optarg);
                pset.popt.topt.recordSep.separator_zero = false;
                break;
            case 's':
                SetVariableBool(pset.vars, "SINGLESTEP");
                break;
            case 'S':
                SetVariableBool(pset.vars, "SINGLELINE");
                break;
            case 't':
                pset.popt.topt.tuples_only = true;
                break;
            case 'T':
                pset.popt.topt.tableAttr = pg_strdup(optarg);
                break;
            case 'U':
                options->username = pg_strdup(optarg);
                break;
            case 'v':
                {
                    char       *value;
                    char       *equal_loc;

                    value = pg_strdup(optarg);
                    equal_loc = strchr(value, '=');
                    if (!equal_loc)
                    {
                        if (!DeleteVariable(pset.vars, value))
                            exit(EXIT_FAILURE); /* error already printed */
                    }
                    else
                    {
                        *equal_loc = '\0';
                        if (!SetVariable(pset.vars, value, equal_loc + 1))
                            exit(EXIT_FAILURE); /* error already printed */
                    }

                    free(value);
                    break;
                }
            case 'V':
                showVersion();
                exit(EXIT_SUCCESS);
            case 'w':
                pset.getPassword = TRI_NO;
                break;
            case 'W':
                pset.getPassword = TRI_YES;
                break;
            case 'x':
                pset.popt.topt.expanded = true;
                break;
            case 'X':
                options->no_psqlrc = true;
                break;
            case 'z':
                pset.popt.topt.fieldSep.separator_zero = true;
                break;
            case '0':
                pset.popt.topt.recordSep.separator_zero = true;
                break;
            case '1':
                options->single_txn = true;
                break;
            case '?':
                if (optind <= argc &&
                    strcmp(argv[optind - 1], "-?") == 0)
                {
                    /* actual help option given */
                    usage(NOPAGER);
                    exit(EXIT_SUCCESS);
                }
                else
                {
                    /* getopt error (unknown option or missing argument) */
                    goto unknown_option;
                }
                break;
            case 1:
                {
                    if (!optarg || strcmp(optarg, "options") == 0)
                        usage(NOPAGER);
                    else if (optarg && strcmp(optarg, "commands") == 0)
                        slashUsage(NOPAGER);
                    else if (optarg && strcmp(optarg, "variables") == 0)
                        helpVariables(NOPAGER);
                    else
                        goto unknown_option;

                    exit(EXIT_SUCCESS);
                }
                break;
            case 2:
                pset.popt.topt.format = PRINT_CSV;
                break;
            default:
        unknown_option:
                fprintf(stderr, _("Try \"%s --help\" for more information.\n"),
                        pset.progname);
                exit(EXIT_FAILURE);
                break;
        }
    }

    /*
     * if we still have arguments, use it as the database name and username
     */
    while (argc - optind >= 1)
    {
        if (!options->dbname)
            options->dbname = argv[optind];
        else if (!options->username)
            options->username = argv[optind];
        else if (!pset.quiet)
            pg_log_warning("extra command-line argument \"%s\" ignored",
                           argv[optind]);

        optind++;
    }
}


/*
 * Append a new item to the end of the SimpleActionList.
 * Note that "val" is copied if it's not NULL.
 */
static void
simple_action_list_append(SimpleActionList *list,
                          enum _actions action, const char *val)
{
    SimpleActionListCell *cell;

    cell = (SimpleActionListCell *) pg_malloc(sizeof(SimpleActionListCell));

    cell->next = NULL;
    cell->action = action;
    if (val)
        cell->val = pg_strdup(val);
    else
        cell->val = NULL;

    if (list->tail)
        list->tail->next = cell;
    else
        list->head = cell;
    list->tail = cell;
}


/*
 * Load .psqlrc file, if found.
 */
static void
process_psqlrc(char *argv0)
{
    char        home[MAXPGPATH];
    char        rc_file[MAXPGPATH];
    char        my_exec_path[MAXPGPATH];
    char        etc_path[MAXPGPATH];
    char       *envrc = getenv("PSQLRC");

    if (find_my_exec(argv0, my_exec_path) < 0)
    {
        pg_log_fatal("could not find own program executable");
        exit(EXIT_FAILURE);
    }

    get_etc_path(my_exec_path, etc_path);

    snprintf(rc_file, MAXPGPATH, "%s/%s", etc_path, SYSPSQLRC);
    process_psqlrc_file(rc_file);

    if (envrc != NULL && strlen(envrc) > 0)
    {
        /* might need to free() this */
        char       *envrc_alloc = pstrdup(envrc);

        expand_tilde(&envrc_alloc);
        process_psqlrc_file(envrc_alloc);
    }
    else if (get_home_path(home))
    {
        snprintf(rc_file, MAXPGPATH, "%s/%s", home, PSQLRC);
        process_psqlrc_file(rc_file);
    }
}



static void
process_psqlrc_file(char *filename)
{
    char       *psqlrc_minor,
               *psqlrc_major;

#if defined(WIN32) && (!defined(__MINGW32__))
#define R_OK 4
#endif

    psqlrc_minor = psprintf("%s-%s", filename, PG_VERSION);
    psqlrc_major = psprintf("%s-%s", filename, PG_MAJORVERSION);

    /* check for minor version first, then major, then no version */
    if (access(psqlrc_minor, R_OK) == 0)
        (void) process_file(psqlrc_minor, false);
    else if (access(psqlrc_major, R_OK) == 0)
        (void) process_file(psqlrc_major, false);
    else if (access(filename, R_OK) == 0)
        (void) process_file(filename, false);

    free(psqlrc_minor);
    free(psqlrc_major);
}



/* showVersion
 *
 * This output format is intended to match GNU standards.
 */
static void
showVersion(void)
{
    puts("psql (PostgreSQL) " PG_VERSION);
}



/*
 * Substitute hooks and assign hooks for psql variables.
 *
 * This isn't an amazingly good place for them, but neither is anywhere else.
 *
 * By policy, every special variable that controls any psql behavior should
 * have one or both hooks, even if they're just no-ops.  This ensures that
 * the variable will remain present in variables.c's list even when unset,
 * which ensures that it's known to tab completion.
 */

static char *
bool_substitute_hook(char *newval)
{
    if (newval == NULL)
    {
        /* "\unset FOO" becomes "\set FOO off" */
        newval = pg_strdup("off");
    }
    else if (newval[0] == '\0')
    {
        /* "\set FOO" becomes "\set FOO on" */
        pg_free(newval);
        newval = pg_strdup("on");
    }
    return newval;
}

static bool
autocommit_hook(const char *newval)
{
    return ParseVariableBool(newval, "AUTOCOMMIT", &pset.autocommit);
}

static bool
on_error_stop_hook(const char *newval)
{
    return ParseVariableBool(newval, "ON_ERROR_STOP", &pset.on_error_stop);
}

static bool
quiet_hook(const char *newval)
{
    return ParseVariableBool(newval, "QUIET", &pset.quiet);
}

static bool
singleline_hook(const char *newval)
{
    return ParseVariableBool(newval, "SINGLELINE", &pset.singleline);
}

static bool
singlestep_hook(const char *newval)
{
    return ParseVariableBool(newval, "SINGLESTEP", &pset.singlestep);
}

static char *
fetch_count_substitute_hook(char *newval)
{
    if (newval == NULL)
        newval = pg_strdup("0");
    return newval;
}

static bool
fetch_count_hook(const char *newval)
{
    return ParseVariableNum(newval, "FETCH_COUNT", &pset.fetch_count);
}

static bool
histfile_hook(const char *newval)
{
    /*
     * Someday we might try to validate the filename, but for now, this is
     * just a placeholder to ensure HISTFILE is known to tab completion.
     */
    return true;
}

static char *
histsize_substitute_hook(char *newval)
{
    if (newval == NULL)
        newval = pg_strdup("500");
    return newval;
}

static bool
histsize_hook(const char *newval)
{
    return ParseVariableNum(newval, "HISTSIZE", &pset.histsize);
}

static char *
ignoreeof_substitute_hook(char *newval)
{
    int         dummy;

    /*
     * This tries to mimic the behavior of bash, to wit "If set, the value is
     * the number of consecutive EOF characters which must be typed as the
     * first characters on an input line before bash exits.  If the variable
     * exists but does not have a numeric value, or has no value, the default
     * value is 10.  If it does not exist, EOF signifies the end of input to
     * the shell."  Unlike bash, however, we insist on the stored value
     * actually being a valid integer.
     */
    if (newval == NULL)
        newval = pg_strdup("0");
    else if (!ParseVariableNum(newval, NULL, &dummy))
        newval = pg_strdup("10");
    return newval;
}

static bool
ignoreeof_hook(const char *newval)
{
    return ParseVariableNum(newval, "IGNOREEOF", &pset.ignoreeof);
}

static char *
echo_substitute_hook(char *newval)
{
    if (newval == NULL)
        newval = pg_strdup("none");
    return newval;
}

static bool
echo_hook(const char *newval)
{
    Assert(newval != NULL);     /* else substitute hook messed up */
    if (pg_strcasecmp(newval, "queries") == 0)
        pset.echo = PSQL_ECHO_QUERIES;
    else if (pg_strcasecmp(newval, "errors") == 0)
        pset.echo = PSQL_ECHO_ERRORS;
    else if (pg_strcasecmp(newval, "all") == 0)
        pset.echo = PSQL_ECHO_ALL;
    else if (pg_strcasecmp(newval, "none") == 0)
        pset.echo = PSQL_ECHO_NONE;
    else
    {
        PsqlVarEnumError("ECHO", newval, "none, errors, queries, all");
        return false;
    }
    return true;
}

static bool
echo_hidden_hook(const char *newval)
{
    Assert(newval != NULL);     /* else substitute hook messed up */
    if (pg_strcasecmp(newval, "noexec") == 0)
        pset.echo_hidden = PSQL_ECHO_HIDDEN_NOEXEC;
    else
    {
        bool        on_off;

        if (ParseVariableBool(newval, NULL, &on_off))
            pset.echo_hidden = on_off ? PSQL_ECHO_HIDDEN_ON : PSQL_ECHO_HIDDEN_OFF;
        else
        {
            PsqlVarEnumError("ECHO_HIDDEN", newval, "on, off, noexec");
            return false;
        }
    }
    return true;
}

static bool
on_error_rollback_hook(const char *newval)
{
    Assert(newval != NULL);     /* else substitute hook messed up */
    if (pg_strcasecmp(newval, "interactive") == 0)
        pset.on_error_rollback = PSQL_ERROR_ROLLBACK_INTERACTIVE;
    else
    {
        bool        on_off;

        if (ParseVariableBool(newval, NULL, &on_off))
            pset.on_error_rollback = on_off ? PSQL_ERROR_ROLLBACK_ON : PSQL_ERROR_ROLLBACK_OFF;
        else
        {
            PsqlVarEnumError("ON_ERROR_ROLLBACK", newval, "on, off, interactive");
            return false;
        }
    }
    return true;
}

static char *
comp_keyword_case_substitute_hook(char *newval)
{
    if (newval == NULL)
        newval = pg_strdup("preserve-upper");
    return newval;
}

static bool
comp_keyword_case_hook(const char *newval)
{
    Assert(newval != NULL);     /* else substitute hook messed up */
    if (pg_strcasecmp(newval, "preserve-upper") == 0)
        pset.comp_case = PSQL_COMP_CASE_PRESERVE_UPPER;
    else if (pg_strcasecmp(newval, "preserve-lower") == 0)
        pset.comp_case = PSQL_COMP_CASE_PRESERVE_LOWER;
    else if (pg_strcasecmp(newval, "upper") == 0)
        pset.comp_case = PSQL_COMP_CASE_UPPER;
    else if (pg_strcasecmp(newval, "lower") == 0)
        pset.comp_case = PSQL_COMP_CASE_LOWER;
    else
    {
        PsqlVarEnumError("COMP_KEYWORD_CASE", newval,
                         "lower, upper, preserve-lower, preserve-upper");
        return false;
    }
    return true;
}

static char *
histcontrol_substitute_hook(char *newval)
{
    if (newval == NULL)
        newval = pg_strdup("none");
    return newval;
}

static bool
histcontrol_hook(const char *newval)
{
    Assert(newval != NULL);     /* else substitute hook messed up */
    if (pg_strcasecmp(newval, "ignorespace") == 0)
        pset.histcontrol = hctl_ignorespace;
    else if (pg_strcasecmp(newval, "ignoredups") == 0)
        pset.histcontrol = hctl_ignoredups;
    else if (pg_strcasecmp(newval, "ignoreboth") == 0)
        pset.histcontrol = hctl_ignoreboth;
    else if (pg_strcasecmp(newval, "none") == 0)
        pset.histcontrol = hctl_none;
    else
    {
        PsqlVarEnumError("HISTCONTROL", newval,
                         "none, ignorespace, ignoredups, ignoreboth");
        return false;
    }
    return true;
}

static bool
prompt1_hook(const char *newval)
{
    pset.prompt1 = newval ? newval : "";
    return true;
}

static bool
prompt2_hook(const char *newval)
{
    pset.prompt2 = newval ? newval : "";
    return true;
}

static bool
prompt3_hook(const char *newval)
{
    pset.prompt3 = newval ? newval : "";
    return true;
}

static char *
verbosity_substitute_hook(char *newval)
{
    if (newval == NULL)
        newval = pg_strdup("default");
    return newval;
}

static bool
verbosity_hook(const char *newval)
{
    Assert(newval != NULL);     /* else substitute hook messed up */
    if (pg_strcasecmp(newval, "default") == 0)
        pset.verbosity = PQERRORS_DEFAULT;
    else if (pg_strcasecmp(newval, "verbose") == 0)
        pset.verbosity = PQERRORS_VERBOSE;
    else if (pg_strcasecmp(newval, "terse") == 0)
        pset.verbosity = PQERRORS_TERSE;
    else if (pg_strcasecmp(newval, "sqlstate") == 0)
        pset.verbosity = PQERRORS_SQLSTATE;
    else
    {
        PsqlVarEnumError("VERBOSITY", newval, "default, verbose, terse, sqlstate");
        return false;
    }

    if (pset.db)
        PQsetErrorVerbosity(pset.db, pset.verbosity);
    return true;
}

static char *
show_context_substitute_hook(char *newval)
{
    if (newval == NULL)
        newval = pg_strdup("errors");
    return newval;
}

static bool
show_context_hook(const char *newval)
{
    Assert(newval != NULL);     /* else substitute hook messed up */
    if (pg_strcasecmp(newval, "never") == 0)
        pset.show_context = PQSHOW_CONTEXT_NEVER;
    else if (pg_strcasecmp(newval, "errors") == 0)
        pset.show_context = PQSHOW_CONTEXT_ERRORS;
    else if (pg_strcasecmp(newval, "always") == 0)
        pset.show_context = PQSHOW_CONTEXT_ALWAYS;
    else
    {
        PsqlVarEnumError("SHOW_CONTEXT", newval, "never, errors, always");
        return false;
    }

    if (pset.db)
        PQsetErrorContextVisibility(pset.db, pset.show_context);
    return true;
}

static bool
hide_tableam_hook(const char *newval)
{
    return ParseVariableBool(newval, "HIDE_TABLEAM", &pset.hide_tableam);
}

static void
EstablishVariableSpace(void)
{
    pset.vars = CreateVariableSpace();

    SetVariableHooks(pset.vars, "AUTOCOMMIT",
                     bool_substitute_hook,
                     autocommit_hook);
    SetVariableHooks(pset.vars, "ON_ERROR_STOP",
                     bool_substitute_hook,
                     on_error_stop_hook);
    SetVariableHooks(pset.vars, "QUIET",
                     bool_substitute_hook,
                     quiet_hook);
    SetVariableHooks(pset.vars, "SINGLELINE",
                     bool_substitute_hook,
                     singleline_hook);
    SetVariableHooks(pset.vars, "SINGLESTEP",
                     bool_substitute_hook,
                     singlestep_hook);
    SetVariableHooks(pset.vars, "FETCH_COUNT",
                     fetch_count_substitute_hook,
                     fetch_count_hook);
    SetVariableHooks(pset.vars, "HISTFILE",
                     NULL,
                     histfile_hook);
    SetVariableHooks(pset.vars, "HISTSIZE",
                     histsize_substitute_hook,
                     histsize_hook);
    SetVariableHooks(pset.vars, "IGNOREEOF",
                     ignoreeof_substitute_hook,
                     ignoreeof_hook);
    SetVariableHooks(pset.vars, "ECHO",
                     echo_substitute_hook,
                     echo_hook);
    SetVariableHooks(pset.vars, "ECHO_HIDDEN",
                     bool_substitute_hook,
                     echo_hidden_hook);
    SetVariableHooks(pset.vars, "ON_ERROR_ROLLBACK",
                     bool_substitute_hook,
                     on_error_rollback_hook);
    SetVariableHooks(pset.vars, "COMP_KEYWORD_CASE",
                     comp_keyword_case_substitute_hook,
                     comp_keyword_case_hook);
    SetVariableHooks(pset.vars, "HISTCONTROL",
                     histcontrol_substitute_hook,
                     histcontrol_hook);
    SetVariableHooks(pset.vars, "PROMPT1",
                     NULL,
                     prompt1_hook);
    SetVariableHooks(pset.vars, "PROMPT2",
                     NULL,
                     prompt2_hook);
    SetVariableHooks(pset.vars, "PROMPT3",
                     NULL,
                     prompt3_hook);
    SetVariableHooks(pset.vars, "VERBOSITY",
                     verbosity_substitute_hook,
                     verbosity_hook);
    SetVariableHooks(pset.vars, "SHOW_CONTEXT",
                     show_context_substitute_hook,
                     show_context_hook);
    SetVariableHooks(pset.vars, "HIDE_TABLEAM",
                     bool_substitute_hook,
                     hide_tableam_hook);
}