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vis.c

/*    $OpenBSD: vis.c,v 1.19 2005/09/01 17:15:49 millert 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 <limits.h>
#include <ctype.h>
#include <string.h>
#include "vis.h"

#define     isoctal(c)  (((u_char)(c)) >= '0' && ((u_char)(c)) <= '7')
#define     isvisible(c)                                          \
      (((u_int)(c) <= UCHAR_MAX && isascii((u_char)(c)) &&        \
      (((c) != '*' && (c) != '?' && (c) != '[' && (c) != '#') ||  \
            (flag & VIS_GLOB) == 0) && isgraph((u_char)(c))) ||   \
      ((flag & VIS_SP) == 0 && (c) == ' ') ||                     \
      ((flag & VIS_TAB) == 0 && (c) == '\t') ||             \
      ((flag & VIS_NL) == 0 && (c) == '\n') ||              \
      ((flag & VIS_SAFE) && ((c) == '\b' ||                       \
            (c) == '\007' || (c) == '\r' ||                       \
            isgraph((u_char)(c)))))

/*
 * vis - visually encode characters
 */
char *
vis(char *dst, int c, int flag, int nextc)
{
      if (isvisible(c)) {
            *dst++ = c;
            if (c == '\\' && (flag & VIS_NOSLASH) == 0)
                  *dst++ = '\\';
            *dst = '\0';
            return (dst);
      }

      if (flag & 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) == ' ') || (flag & VIS_OCTAL) ||
          ((flag & 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 ((flag & VIS_NOSLASH) == 0)
            *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);
}

/*
 * 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);
}

int
strnvis(char *dst, const char *src, size_t siz, int flag)
{
      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)) {
                  i = 1;
                  *dst++ = c;
                  if (c == '\\' && (flag & VIS_NOSLASH) == 0) {
                        /* need space for the extra '\\' */
                        if (dst < end)
                              *dst++ = '\\';
                        else {
                              dst--;
                              i = 2;
                              break;
                        }
                  }
                  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
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);
}

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