/* buf.c: This file contains the scratch-file buffer routines for the
   ed line editor. */
/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 1993 Andrew Moore, Talke Studio.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#include <sys/file.h>
#include <sys/stat.h>

#include "ed.h"


static FILE *sfp;                       /* scratch file pointer */
static off_t sfseek;                    /* scratch file position */
static int seek_write;                  /* seek before writing */
static line_t buffer_head;              /* incore buffer */

/* get_sbuf_line: get a line of text from the scratch file; return pointer
   to the text */
char *
get_sbuf_line(line_t *lp)
{
        static char *sfbuf = NULL;      /* buffer */
        static size_t sfbufsz;          /* buffer size */

        size_t len;

        if (lp == &buffer_head)
                return NULL;
        seek_write = 1;                         /* force seek on write */
        /* out of position */
        if (sfseek != lp->seek) {
                sfseek = lp->seek;
                if (fseeko(sfp, sfseek, SEEK_SET) < 0) {
                        fprintf(stderr, "%s\n", strerror(errno));
                        errmsg = "cannot seek temp file";
                        return NULL;
                }
        }
        len = lp->len;
        REALLOC(sfbuf, sfbufsz, len + 1, NULL);
        if (fread(sfbuf, sizeof(char), len, sfp) != len) {
                fprintf(stderr, "%s\n", strerror(errno));
                errmsg = "cannot read temp file";
                return NULL;
        }
        sfseek += len;                          /* update file position */
        sfbuf[len] = '\0';
        return sfbuf;
}


/* put_sbuf_line: write a line of text to the scratch file and add a line node
   to the editor buffer;  return a pointer to the end of the text */
const char *
put_sbuf_line(const char *cs)
{
        line_t *lp;
        size_t len;
        const char *s;

        if ((lp = (line_t *) malloc(sizeof(line_t))) == NULL) {
                fprintf(stderr, "%s\n", strerror(errno));
                errmsg = "out of memory";
                return NULL;
        }
        /* assert: cs is '\n' terminated */
        for (s = cs; *s != '\n'; s++)
                ;
        if (s - cs >= LINECHARS) {
                errmsg = "line too long";
                free(lp);
                return NULL;
        }
        len = s - cs;
        /* out of position */
        if (seek_write) {
                if (fseeko(sfp, (off_t)0, SEEK_END) < 0) {
                        fprintf(stderr, "%s\n", strerror(errno));
                        errmsg = "cannot seek temp file";
                        free(lp);
                        return NULL;
                }
                sfseek = ftello(sfp);
                seek_write = 0;
        }
        /* assert: SPL1() */
        if (fwrite(cs, sizeof(char), len, sfp) != len) {
                sfseek = -1;
                fprintf(stderr, "%s\n", strerror(errno));
                errmsg = "cannot write temp file";
                free(lp);
                return NULL;
        }
        lp->len = len;
        lp->seek  = sfseek;
        add_line_node(lp);
        sfseek += len;                  /* update file position */
        return ++s;
}


/* add_line_node: add a line node in the editor buffer after the current line */
void
add_line_node(line_t *lp)
{
        line_t *cp;

        cp = get_addressed_line_node(current_addr);                             /* this get_addressed_line_node last! */
        INSQUE(lp, cp);
        addr_last++;
        current_addr++;
}


/* get_line_node_addr: return line number of pointer */
long
get_line_node_addr(line_t *lp)
{
        line_t *cp = &buffer_head;
        long n = 0;

        while (cp != lp && (cp = cp->q_forw) != &buffer_head)
                n++;
        if (n && cp == &buffer_head) {
                errmsg = "invalid address";
                return ERR;
         }
         return n;
}


/* get_addressed_line_node: return pointer to a line node in the editor buffer */
line_t *
get_addressed_line_node(long n)
{
        static line_t *lp = &buffer_head;
        static long on = 0;

        SPL1();
        if (n > on)
                if (n <= (on + addr_last) >> 1)
                        for (; on < n; on++)
                                lp = lp->q_forw;
                else {
                        lp = buffer_head.q_back;
                        for (on = addr_last; on > n; on--)
                                lp = lp->q_back;
                }
        else
                if (n >= on >> 1)
                        for (; on > n; on--)
                                lp = lp->q_back;
                else {
                        lp = &buffer_head;
                        for (on = 0; on < n; on++)
                                lp = lp->q_forw;
                }
        SPL0();
        return lp;
}

static char sfn[15] = "";                       /* scratch file name */

/* open_sbuf: open scratch file */
int
open_sbuf(void)
{
        int fd;
        int u;

        isbinary = newline_added = 0;
        u = umask(077);
        strcpy(sfn, "/tmp/ed.XXXXXX");
        if ((fd = mkstemp(sfn)) == -1 ||
            (sfp = fdopen(fd, "w+")) == NULL) {
                if (fd != -1)
                        close(fd);
                perror(sfn);
                errmsg = "cannot open temp file";
                umask(u);
                return ERR;
        }
        umask(u);
        return 0;
}


/* close_sbuf: close scratch file */
int
close_sbuf(void)
{
        if (sfp) {
                if (fclose(sfp) < 0) {
                        fprintf(stderr, "%s: %s\n", sfn, strerror(errno));
                        errmsg = "cannot close temp file";
                        return ERR;
                }
                sfp = NULL;
                unlink(sfn);
        }
        sfseek = seek_write = 0;
        return 0;
}


/* quit: remove_lines scratch file and exit */
void
quit(int n)
{
        if (sfp) {
                fclose(sfp);
                unlink(sfn);
        }
        exit(n);
}


static unsigned char ctab[256];         /* character translation table */

/* init_buffers: open scratch buffer; initialize line queue */
void
init_buffers(void)
{
        int i = 0;

        /* Read stdin one character at a time to avoid i/o contention
           with shell escapes invoked by nonterminal input, e.g.,
           ed - <<EOF
           !cat
           hello, world
           EOF */
        setbuffer(stdin, stdinbuf, 1);

        /* Ensure stdout is line buffered. This avoids bogus delays
           of output if stdout is piped through utilities to a terminal. */
        setvbuf(stdout, NULL, _IOLBF, 0);
        if (open_sbuf() < 0)
                quit(2);
        REQUE(&buffer_head, &buffer_head);
        for (i = 0; i < 256; i++)
                ctab[i] = i;
}


/* translit_text: translate characters in a string */
char *
translit_text(char *s, int len, int from, int to)
{
        static int i = 0;

        unsigned char *us;

        ctab[i] = i;                    /* restore table to initial state */
        ctab[i = from] = to;
        for (us = (unsigned char *) s; len-- > 0; us++)
                *us = ctab[*us];
        return s;
}