root/usr.bin/vi/ex/ex_bang.c
/*      $OpenBSD: ex_bang.c,v 1.13 2025/07/30 22:19:13 millert Exp $    */

/*-
 * Copyright (c) 1992, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 * Copyright (c) 1992, 1993, 1994, 1995, 1996
 *      Keith Bostic.  All rights reserved.
 *
 * See the LICENSE file for redistribution information.
 */

#include "config.h"

#include <sys/types.h>
#include <sys/queue.h>
#include <sys/time.h>

#include <bitstring.h>
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "../common/common.h"
#include "../vi/vi.h"

/*
 * ex_bang -- :[line [,line]] ! command
 *
 * Pass the rest of the line after the ! character to the program named by
 * the O_SHELL option.
 *
 * Historical vi did NOT do shell expansion on the arguments before passing
 * them, only file name expansion.  This means that the O_SHELL program got
 * "$t" as an argument if that is what the user entered.  Also, there's a
 * special expansion done for the bang command.  Any exclamation points in
 * the user's argument are replaced by the last, expanded ! command.
 *
 * There's some fairly amazing slop in this routine to make the different
 * ways of getting here display the right things.  It took a long time to
 * get it right (wrong?), so be careful.
 *
 * PUBLIC: int ex_bang(SCR *, EXCMD *);
 */
int
ex_bang(SCR *sp, EXCMD *cmdp)
{
        enum filtertype ftype;
        ARGS *ap;
        EX_PRIVATE *exp;
        MARK rm;
        recno_t lno;
        int rval;
        const char *msg;

        ap = cmdp->argv[0];
        if (ap->len == 0) {
                ex_emsg(sp, cmdp->cmd->usage, EXM_USAGE);
                return (1);
        }

        /* Set the "last bang command" remembered value. */
        exp = EXP(sp);
        free(exp->lastbcomm);
        if ((exp->lastbcomm = strdup(ap->bp)) == NULL) {
                msgq(sp, M_SYSERR, NULL);
                return (1);
        }

        /*
         * If the command was modified by the expansion, it was historically
         * redisplayed.
         */
        if (F_ISSET(cmdp, E_MODIFY) && !F_ISSET(sp, SC_EX_SILENT)) {
                /*
                 * Display the command if modified.  Historic ex/vi displayed
                 * the command if it was modified due to file name and/or bang
                 * expansion.  If piping lines in vi, it would be immediately
                 * overwritten by any error or line change reporting.
                 */
                if (F_ISSET(sp, SC_VI))
                        vs_update(sp, "!", ap->bp);
                else {
                        (void)ex_printf(sp, "!%s\n", ap->bp);
                        (void)ex_fflush(sp);
                }
        }

        /*
         * If no addresses were specified, run the command.  If there's an
         * underlying file, it's been modified and autowrite is set, write
         * the file back.  If the file has been modified, autowrite is not
         * set and the warn option is set, tell the user about the file.
         */
        if (cmdp->addrcnt == 0) {
                msg = NULL;
                if (sp->ep != NULL && F_ISSET(sp->ep, F_MODIFIED)) {
                        if (O_ISSET(sp, O_AUTOWRITE)) {
                                if (file_aw(sp, FS_ALL))
                                        return (0);
                        } else if (O_ISSET(sp, O_WARN) &&
                            !F_ISSET(sp, SC_EX_SILENT))
                                msg = "File modified since last write.";
                }

                /* If we're still in a vi screen, move out explicitly. */
                (void)ex_exec_proc(sp,
                    cmdp, ap->bp, msg, !F_ISSET(sp, SC_EX | SC_SCR_EXWROTE));
        }

        /*
         * If addresses were specified, pipe lines from the file through the
         * command.
         *
         * Historically, vi lines were replaced by both the stdout and stderr
         * lines of the command, but ex lines by only the stdout lines.  This
         * makes no sense to me, so nvi makes it consistent for both, and
         * matches vi's historic behavior.
         */
        else {
                NEEDFILE(sp, cmdp);

                /* Autoprint is set historically, even if the command fails. */
                F_SET(cmdp, E_AUTOPRINT);

                /*
                 * !!!
                 * Historical vi permitted "!!" in an empty file.  When this
                 * happens, we arrive here with two addresses of 1,1 and a
                 * bad attitude.  The simple solution is to turn it into a
                 * FILTER_READ operation, with the exception that stdin isn't
                 * opened for the utility, and the cursor position isn't the
                 * same.  The only historic glitch (I think) is that we don't
                 * put an empty line into the default cut buffer, as historic
                 * vi did.  Imagine, if you can, my disappointment.
                 */
                ftype = FILTER_BANG;
                if (cmdp->addr1.lno == 1 && cmdp->addr2.lno == 1) {
                        if (db_last(sp, &lno))
                                return (1);
                        if (lno == 0) {
                                cmdp->addr1.lno = cmdp->addr2.lno = 0;
                                ftype = FILTER_RBANG;
                        }
                }
                rval = ex_filter(sp, cmdp,
                    &cmdp->addr1, &cmdp->addr2, &rm, ap->bp, ftype);

                /*
                 * If in vi mode, move to the first nonblank.
                 *
                 * !!!
                 * Historic vi wasn't consistent in this area -- if you used
                 * a forward motion it moved to the first nonblank, but if you
                 * did a backward motion it didn't.  And, if you followed a
                 * backward motion with a forward motion, it wouldn't move to
                 * the nonblank for either.  Going to the nonblank generally
                 * seems more useful and consistent, so we do it.
                 */
                sp->lno = rm.lno;
                if (F_ISSET(sp, SC_VI)) {
                        sp->cno = 0;
                        (void)nonblank(sp, sp->lno, &sp->cno);
                } else
                        sp->cno = rm.cno;
        }

        /* Ex terminates with a bang, even if the command fails. */
        if (!F_ISSET(sp, SC_VI) && !F_ISSET(sp, SC_EX_SILENT))
                (void)ex_puts(sp, "!\n");

        /* If addresses were specified, apply expandtab to the new text. */
        if (cmdp->addrcnt != 0 && O_ISSET(sp, O_EXPANDTAB))
                ex_retab(sp, cmdp);

        /*
         * XXX
         * The ! commands never return an error, so that autoprint always
         * happens in the ex parser.
         */
        return (0);
}