prompt.c

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/*
 * psql - the PostgreSQL interactive terminal
 *
 * Copyright (c) 2000-2025, PostgreSQL Global Development Group
 *
 * src/bin/psql/prompt.c
 */
#include "postgres_fe.h"
 
#ifdef WIN32
#include <io.h>
#include <win32.h>
#endif
 
#include "common.h"
#include "common/string.h"
#include "input.h"
#include "libpq/pqcomm.h"
#include "prompt.h"
#include "settings.h"
 
/*--------------------------
 * get_prompt
 *
 * Returns a statically allocated prompt made by interpolating certain
 * tcsh style escape sequences into pset.vars "PROMPT1|2|3".
 * (might not be completely multibyte safe)
 *
 * Defined interpolations are:
 * %M - database server "hostname.domainname", "[local]" for AF_UNIX
 *      sockets, "[local:/dir/name]" if not default
 * %m - like %M, but hostname only (before first dot), or always "[local]"
 * %p - backend pid
 * %P - pipeline status: on, off or abort
 * %> - database server port number
 * %n - database user name
 * %S - search_path
 * %s - service
 * %/ - current database
 * %~ - like %/ but "~" when database name equals user name
 * %w - whitespace of the same width as the most recent output of PROMPT1
 * %# - "#" if superuser, ">" otherwise
 * %R - in prompt1 normally =, or ^ if single line mode,
 *          or a ! if session is not connected to a database;
 *      in prompt2 -, *, ', or ";
 *      in prompt3 nothing
 * %x - transaction status: empty, *, !, ? (unknown or no connection)
 * %l - The line number inside the current statement, starting from 1.
 * %? - the error code of the last query (not yet implemented)
 * %% - a percent sign
 *
 * %[0-9]          - the character with the given decimal code
 * %0[0-7]         - the character with the given octal code
 * %0x[0-9A-Fa-f]  - the character with the given hexadecimal code
 *
 * %`command`      - The result of executing command in /bin/sh with trailing
 *                   newline stripped.
 * %:name:         - The value of the psql variable 'name'
 * (those will not be rescanned for more escape sequences!)
 *
 * %[ ... %]       - tell readline that the contained text is invisible
 *
 * If the application-wide prompts become NULL somehow, the returned string
 * will be empty (not NULL!).
 *--------------------------
 */
 
char *
get_prompt(promptStatus_t status, ConditionalStack cstack)
{
#define MAX_PROMPT_SIZE 256
    static char destination[MAX_PROMPT_SIZE + 1];
    char        buf[MAX_PROMPT_SIZE + 1];
    bool        esc = false;
    const char *p;
    const char *prompt_string = "? ";
    static size_t last_prompt1_width = 0;
 
    switch (status)
    {
        case PROMPT_READY:
            prompt_string = pset.prompt1;
            break;
 
        case PROMPT_CONTINUE:
        case PROMPT_SINGLEQUOTE:
        case PROMPT_DOUBLEQUOTE:
        case PROMPT_DOLLARQUOTE:
        case PROMPT_COMMENT:
        case PROMPT_PAREN:
            prompt_string = pset.prompt2;
            break;
 
        case PROMPT_COPY:
            prompt_string = pset.prompt3;
            break;
    }
 
    destination[0] = '\0';
 
    for (p = prompt_string;
         *p && strlen(destination) < sizeof(destination) - 1;
         p++)
    {
        memset(buf, 0, sizeof(buf));
        if (esc)
        {
            switch (*p)
            {
                    /* Current database */
                case '/':
                    if (pset.db)
                        strlcpy(buf, PQdb(pset.db), sizeof(buf));
                    break;
                case '~':
                    if (pset.db)
                    {
                        const char *var;
 
                        if (strcmp(PQdb(pset.db), PQuser(pset.db)) == 0 ||
                            ((var = getenv("PGDATABASE")) && strcmp(var, PQdb(pset.db)) == 0))
                            strlcpy(buf, "~", sizeof(buf));
                        else
                            strlcpy(buf, PQdb(pset.db), sizeof(buf));
                    }
                    break;
 
                    /* Whitespace of the same width as the last PROMPT1 */
                case 'w':
                    if (pset.db)
                        memset(buf, ' ',
                               Min(last_prompt1_width, sizeof(buf) - 1));
                    break;
 
                    /* DB server hostname (long/short) */
                case 'M':
                case 'm':
                    if (pset.db)
                    {
                        const char *host = PQhost(pset.db);
 
                        /* INET socket */
                        if (host && host[0] && !is_unixsock_path(host))
                        {
                            strlcpy(buf, host, sizeof(buf));
                            if (*p == 'm')
                                buf[strcspn(buf, ".")] = '\0';
                        }
                        /* UNIX socket */
                        else
                        {
                            if (!host
                                || strcmp(host, DEFAULT_PGSOCKET_DIR) == 0
                                || *p == 'm')
                                strlcpy(buf, "[local]", sizeof(buf));
                            else
                                snprintf(buf, sizeof(buf), "[local:%s]", host);
                        }
                    }
                    break;
                    /* DB server port number */
                case '>':
                    if (pset.db && PQport(pset.db))
                        strlcpy(buf, PQport(pset.db), sizeof(buf));
                    break;
                    /* DB server user name */
                case 'n':
                    if (pset.db)
                        strlcpy(buf, session_username(), sizeof(buf));
                    break;
                    /* search_path */
                case 'S':
                    if (pset.db)
                    {
                        const char *sp = PQparameterStatus(pset.db, "search_path");
 
                        /* Use ? for versions that don't report search_path. */
                        strlcpy(buf, sp ? sp : "?", sizeof(buf));
                    }
                    break;
                    /* service name */
                case 's':
                    {
                        const char *service_name = GetVariable(pset.vars, "SERVICE");
 
                        if (service_name)
                            strlcpy(buf, service_name, sizeof(buf));
                    }
                    break;
                    /* backend pid */
                case 'p':
                    if (pset.db)
                    {
                        int         pid = PQbackendPID(pset.db);
 
                        if (pid)
                            snprintf(buf, sizeof(buf), "%d", pid);
                    }
                    break;
                    /* pipeline status */
                case 'P':
                    {
                        PGpipelineStatus status = PQpipelineStatus(pset.db);
 
                        if (status == PQ_PIPELINE_ON)
                            strlcpy(buf, "on", sizeof(buf));
                        else if (status == PQ_PIPELINE_ABORTED)
                            strlcpy(buf, "abort", sizeof(buf));
                        else
                            strlcpy(buf, "off", sizeof(buf));
                        break;
                    }
 
                case '0':
                case '1':
                case '2':
                case '3':
                case '4':
                case '5':
                case '6':
                case '7':
                    *buf = (char) strtol(p, unconstify(char **, &p), 8);
                    --p;
                    break;
                case 'R':
                    switch (status)
                    {
                        case PROMPT_READY:
                            if (cstack != NULL && !conditional_active(cstack))
                                buf[0] = '@';
                            else if (!pset.db)
                                buf[0] = '!';
                            else if (!pset.singleline)
                                buf[0] = '=';
                            else
                                buf[0] = '^';
                            break;
                        case PROMPT_CONTINUE:
                            buf[0] = '-';
                            break;
                        case PROMPT_SINGLEQUOTE:
                            buf[0] = '\'';
                            break;
                        case PROMPT_DOUBLEQUOTE:
                            buf[0] = '"';
                            break;
                        case PROMPT_DOLLARQUOTE:
                            buf[0] = '$';
                            break;
                        case PROMPT_COMMENT:
                            buf[0] = '*';
                            break;
                        case PROMPT_PAREN:
                            buf[0] = '(';
                            break;
                        default:
                            buf[0] = '\0';
                            break;
                    }
                    break;
 
                case 'x':
                    if (!pset.db)
                        buf[0] = '?';
                    else
                        switch (PQtransactionStatus(pset.db))
                        {
                            case PQTRANS_IDLE:
                                buf[0] = '\0';
                                break;
                            case PQTRANS_ACTIVE:
                            case PQTRANS_INTRANS:
                                buf[0] = '*';
                                break;
                            case PQTRANS_INERROR:
                                buf[0] = '!';
                                break;
                            default:
                                buf[0] = '?';
                                break;
                        }
                    break;
 
                case 'l':
                    snprintf(buf, sizeof(buf), UINT64_FORMAT, pset.stmt_lineno);
                    break;
 
                case '?':
                    /* not here yet */
                    break;
 
                case '#':
                    if (is_superuser())
                        buf[0] = '#';
                    else
                        buf[0] = '>';
                    break;
 
                    /* execute command */
                case '`':
                    {
                        int         cmdend = strcspn(p + 1, "`");
                        char       *file = pnstrdup(p + 1, cmdend);
                        FILE       *fd;
 
                        fflush(NULL);
                        fd = popen(file, "r");
                        if (fd)
                        {
                            if (fgets(buf, sizeof(buf), fd) == NULL)
                                buf[0] = '\0';
                            pclose(fd);
                        }
 
                        /* strip trailing newline and carriage return */
                        (void) pg_strip_crlf(buf);
 
                        free(file);
                        p += cmdend + 1;
                        break;
                    }
 
                    /* interpolate variable */
                case ':':
                    {
                        int         nameend = strcspn(p + 1, ":");
                        char       *name = pnstrdup(p + 1, nameend);
                        const char *val;
 
                        val = GetVariable(pset.vars, name);
                        if (val)
                            strlcpy(buf, val, sizeof(buf));
                        free(name);
                        p += nameend + 1;
                        break;
                    }
 
                case '[':
                case ']':
#if defined(USE_READLINE) && defined(RL_PROMPT_START_IGNORE)
 
                    /*
                     * readline >=4.0 undocumented feature: non-printing
                     * characters in prompt strings must be marked as such, in
                     * order to properly display the line during editing.
                     */
                    buf[0] = (*p == '[') ? RL_PROMPT_START_IGNORE : RL_PROMPT_END_IGNORE;
                    buf[1] = '\0';
#endif                          /* USE_READLINE */
                    break;
 
                default:
                    buf[0] = *p;
                    buf[1] = '\0';
                    break;
            }
            esc = false;
        }
        else if (*p == '%')
            esc = true;
        else
        {
            buf[0] = *p;
            buf[1] = '\0';
            esc = false;
        }
 
        if (!esc)
            strlcat(destination, buf, sizeof(destination));
    }
 
    /* Compute the visible width of PROMPT1, for PROMPT2's %w */
    if (prompt_string == pset.prompt1)
    {
        char       *p = destination;
        char       *end = p + strlen(p);
        bool        visible = true;
 
        last_prompt1_width = 0;
        while (*p)
        {
#if defined(USE_READLINE) && defined(RL_PROMPT_START_IGNORE)
            if (*p == RL_PROMPT_START_IGNORE)
            {
                visible = false;
                ++p;
            }
            else if (*p == RL_PROMPT_END_IGNORE)
            {
                visible = true;
                ++p;
            }
            else
#endif
            {
                int         chlen,
                            chwidth;
 
                chlen = PQmblen(p, pset.encoding);
                if (p + chlen > end)
                    break;      /* Invalid string */
 
                if (visible)
                {
                    chwidth = PQdsplen(p, pset.encoding);
 
                    if (*p == '\n')
                        last_prompt1_width = 0;
                    else if (chwidth > 0)
                        last_prompt1_width += chwidth;
                }
 
                p += chlen;
            }
        }
    }
 
    return destination;
}