usr/src/contrib/ed/get_line.c

/*-
 * Copyright (c) 1992 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Rodney Ruddock of the University of Guelph.
 *
 * %sccs.include.redist.c%
 */

#ifndef lint
static char sccsid[] = "@(#)get_line.c  5.3 (Berkeley) %G%";
#endif /* not lint */

#include <sys/types.h>

#include <regex.h>
#include <setjmp.h>
#include <stdio.h>
#include <string.h>

#ifdef DBI
#include <db.h>
#endif

#include "ed.h"
#include "extern.h"

/*
 * Get the specified line from the buffer. Note that in the buffer
 * we stored lengths of text, not strings (NULL terminated, except
 * under MEMORY). So we want to put a terminating NULL in for
 * whatever command is going to be handling the line.
 */

/* these variables are here (instead of main and ed.h) because they
 * are only used with the buffer when run under STDIO. STDIO is a
 * resource pig with most of the OS's I've tested this with. The
 * use of these variables improves performance up to 100% in several
 * cases. The piggyness is thus: fseek causes the current STDIO buf
 * to be flushed out and a new one read in...even when it is not necessary!
 * Read 512 (or 1024) when you don't have to for almost every access
 * and you'll slow down too. So these variable are used to control unneeded
 * fseeks.
 * I've been told the newer BSD STDIO has fixed this, but don't
 * currently have a copy.
 */
int file_loc=0;

/* Get a particular line of length len from ed's buffer and place it in
 * 'text', the standard repository for the "current" line.
 */
void
get_line(loc, len)
#ifdef STDIO
        long loc;
#endif
#ifdef DBI
        recno_t loc;
#endif
#ifdef MEMORY
        char *loc;
#endif
        int len;
{
#ifdef DBI
        DBT db_key, db_data;
#endif
        int l_jmp_flag;

        if (l_jmp_flag = setjmp(ctrl_position2)) {
                text[0] = '\0';
                return;
        }

        sigspecial2 = 1;
#ifdef STDIO

        if (loc == 0L) {
                text[0] = '\0';
                return;
        }
        if (file_loc != loc)
                fseek(fhtmp, loc, 0);
        file_seek = 1;
        file_loc = loc + fread(text, sizeof(char), len, fhtmp);
#endif

#ifdef DBI
        if (loc == (recno_t)0) {
                text[0] = '\0';
                return;
        }
        (db_key.data) = &loc;
        (db_key.size) = sizeof(recno_t);
        (dbhtmp->get) (dbhtmp, &db_key, &db_data, (u_int) 0);
        strcpy(text, db_data.data);
#endif

#ifdef MEMORY
        if (loc == (char *)NULL) {
                text[0] = '\0';
                return;
        }
        bcopy(loc, text, len);
#endif
        text[len] = '\0';
        sigspecial2 = 0;
}