/*      $OpenBSD: vis.c,v 1.26 2022/05/04 18:57:50 deraadt Exp $ */
/*-
 * Copyright (c) 1989, 1993
 *      The Regents of the University of California.  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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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/types.h>
#include <errno.h>
#include <ctype.h>
#include <limits.h>
#include <string.h>
#include <stdlib.h>
#include <vis.h>

static int
isoctal(int c)
{
        u_char uc = c;

        return uc >= '0' && uc <= '7';
}

static int
isvisible(int c, int flag)
{
        int vis_sp = flag & VIS_SP;
        int vis_tab = flag & VIS_TAB;
        int vis_nl = flag & VIS_NL;
        int vis_safe = flag & VIS_SAFE;
        int vis_glob = flag & VIS_GLOB;
        int vis_all = flag & VIS_ALL;
        u_char uc = c;

        if (c == '\\' || !vis_all) {
                if ((u_int)c <= UCHAR_MAX && isascii(uc) &&
                    ((c != '*' && c != '?' && c != '[' && c != '#') || !vis_glob) &&
                    isgraph(uc))
                        return 1;
                if (!vis_sp && c == ' ')
                        return 1;
                if (!vis_tab && c == '\t')
                        return 1;
                if (!vis_nl && c == '\n')
                        return 1;
                if (vis_safe && (c == '\b' || c == '\007' || c == '\r' || isgraph(uc)))
                        return 1;
        }
        return 0;
}

/*
 * vis - visually encode characters
 */
char *
vis(char *dst, int c, int flag, int nextc)
{
        int vis_dq = flag & VIS_DQ;
        int vis_noslash = flag & VIS_NOSLASH;
        int vis_cstyle = flag & VIS_CSTYLE;
        int vis_octal = flag & VIS_OCTAL;
        int vis_glob = flag & VIS_GLOB;

        if (isvisible(c, flag)) {
                if ((c == '"' && vis_dq) ||
                    (c == '\\' && !vis_noslash))
                        *dst++ = '\\';
                *dst++ = c;
                *dst = '\0';
                return (dst);
        }

        if (vis_cstyle) {
                switch (c) {
                case '\n':
                        *dst++ = '\\';
                        *dst++ = 'n';
                        goto done;
                case '\r':
                        *dst++ = '\\';
                        *dst++ = 'r';
                        goto done;
                case '\b':
                        *dst++ = '\\';
                        *dst++ = 'b';
                        goto done;
                case '\a':
                        *dst++ = '\\';
                        *dst++ = 'a';
                        goto done;
                case '\v':
                        *dst++ = '\\';
                        *dst++ = 'v';
                        goto done;
                case '\t':
                        *dst++ = '\\';
                        *dst++ = 't';
                        goto done;
                case '\f':
                        *dst++ = '\\';
                        *dst++ = 'f';
                        goto done;
                case ' ':
                        *dst++ = '\\';
                        *dst++ = 's';
                        goto done;
                case '\0':
                        *dst++ = '\\';
                        *dst++ = '0';
                        if (isoctal(nextc)) {
                                *dst++ = '0';
                                *dst++ = '0';
                        }
                        goto done;
                }
        }
        if (((c & 0177) == ' ') || vis_octal ||
            (vis_glob && (c == '*' || c == '?' || c == '[' || c == '#'))) {
                *dst++ = '\\';
                *dst++ = ((u_char)c >> 6 & 07) + '0';
                *dst++ = ((u_char)c >> 3 & 07) + '0';
                *dst++ = ((u_char)c & 07) + '0';
                goto done;
        }
        if (!vis_noslash)
                *dst++ = '\\';
        if (c & 0200) {
                c &= 0177;
                *dst++ = 'M';
        }
        if (iscntrl((u_char)c)) {
                *dst++ = '^';
                if (c == 0177)
                        *dst++ = '?';
                else
                        *dst++ = c + '@';
        } else {
                *dst++ = '-';
                *dst++ = c;
        }
done:
        *dst = '\0';
        return (dst);
}
DEF_WEAK(vis);

/*
 * strvis, strnvis, strvisx - visually encode characters from src into dst
 *      
 *      Dst must be 4 times the size of src to account for possible
 *      expansion.  The length of dst, not including the trailing NULL,
 *      is returned. 
 *
 *      Strnvis will write no more than siz-1 bytes (and will NULL terminate).
 *      The number of bytes needed to fully encode the string is returned.
 *
 *      Strvisx encodes exactly len bytes from src into dst.
 *      This is useful for encoding a block of data.
 */
int
strvis(char *dst, const char *src, int flag)
{
        char c;
        char *start;

        for (start = dst; (c = *src);)
                dst = vis(dst, c, flag, *++src);
        *dst = '\0';
        return (dst - start);
}
DEF_WEAK(strvis);

int
strnvis(char *dst, const char *src, size_t siz, int flag)
{
        int vis_dq = flag & VIS_DQ;
        int vis_noslash = flag & VIS_NOSLASH;
        char *start, *end;
        char tbuf[5];
        int c, i;

        i = 0;
        for (start = dst, end = start + siz - 1; (c = *src) && dst < end; ) {
                if (isvisible(c, flag)) {
                        if ((c == '"' && vis_dq) ||
                            (c == '\\' && !vis_noslash)) {
                                /* need space for the extra '\\' */
                                if (dst + 1 >= end) {
                                        i = 2;
                                        break;
                                }
                                *dst++ = '\\';
                        }
                        i = 1;
                        *dst++ = c;
                        src++;
                } else {
                        i = vis(tbuf, c, flag, *++src) - tbuf;
                        if (dst + i <= end) {
                                memcpy(dst, tbuf, i);
                                dst += i;
                        } else {
                                src--;
                                break;
                        }
                }
        }
        if (siz > 0)
                *dst = '\0';
        if (dst + i > end) {
                /* adjust return value for truncation */
                while ((c = *src))
                        dst += vis(tbuf, c, flag, *++src) - tbuf;
        }
        return (dst - start);
}

int
stravis(char **outp, const char *src, int flag)
{
        char *buf;
        int len, serrno;

        buf = reallocarray(NULL, 4, strlen(src) + 1);
        if (buf == NULL)
                return -1;
        len = strvis(buf, src, flag);
        serrno = errno;
        *outp = realloc(buf, len + 1);
        if (*outp == NULL) {
                *outp = buf;
                errno = serrno;
        }
        return (len);
}

int
strvisx(char *dst, const char *src, size_t len, int flag)
{
        char c;
        char *start;

        for (start = dst; len > 1; len--) {
                c = *src;
                dst = vis(dst, c, flag, *++src);
        }
        if (len)
                dst = vis(dst, *src, flag, '\0');
        *dst = '\0';
        return (dst - start);
}