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    1 /*
    2  *  Project   : tin - a Usenet reader
    3  *  Module    : charset.c
    4  *  Author    : M. Kuhn, T. Burmester
    5  *  Created   : 1993-12-10
    6  *  Updated   : 2021-02-23
    7  *  Notes     : ISO to ascii charset conversion routines
    8  *
    9  * Copyright (c) 1993-2022 Markus Kuhn <mgk25@cl.cam.ac.uk>
   10  * All rights reserved.
   11  *
   12  * Redistribution and use in source and binary forms, with or without
   13  * modification, are permitted provided that the following conditions
   14  * are met:
   15  *
   16  * 1. Redistributions of source code must retain the above copyright notice,
   17  *    this list of conditions and the following disclaimer.
   18  *
   19  * 2. Redistributions in binary form must reproduce the above copyright
   20  *    notice, this list of conditions and the following disclaimer in the
   21  *    documentation and/or other materials provided with the distribution.
   22  *
   23  * 3. Neither the name of the copyright holder nor the names of its
   24  *    contributors may be used to endorse or promote products derived from
   25  *    this software without specific prior written permission.
   26  *
   27  * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   28  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   29  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   30  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
   31  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   32  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   33  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   34  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   35  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   36  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   37  * POSSIBILITY OF SUCH DAMAGE.
   38  */
   39 
   40 
   41 #ifndef TIN_H
   42 #   include "tin.h"
   43 #endif /* !TIN_H */
   44 
   45 /*
   46  *  Table for the iso2asc conversion
   47  *  iso2asc  by  (unrza3@cd4680fs.rrze.uni-erlangen.de)
   48  *  included by  (root@aspic.han.de)
   49  */
   50 
   51 #define SUB "?"
   52 #define ISO_EXTRA   0xa0 /* beginning of second range of printable chars */
   53 
   54 /*
   55  * TABSTOP(x) is the column of the character after the TAB
   56  * at column x. First column is 0, of course.
   57  */
   58 
   59 #define TABSTOP(x)  (((x) - ((x)&7)) + 8)
   60 
   61 static constext *const iso2asc[NUM_ISO_TABLES][256-ISO_EXTRA] =
   62 {
   63     /* universal table for many languages */
   64     {
   65     " ","!","c",SUB,SUB,"Y","|",SUB,"\"","(c)","a","<<","-","-","(R)","-",
   66     " ","+/-","2","3","'","u","P",".",",","1","o",">>"," 1/4"," 1/2"," 3/4","?",
   67     "A","A","A","A","A","A","AE","C","E","E","E","E","I","I","I","I",
   68     "D","N","O","O","O","O","O","x","O","U","U","U","U","Y","Th","ss",
   69     "a","a","a","a","a","a","ae","c","e","e","e","e","i","i","i","i",
   70     "d","n","o","o","o","o","o",":","o","u","u","u","u","y","th","y"
   71     },
   72     /* single-spacing universal table */
   73     {
   74     " ","!","c",SUB,SUB,"Y","|",SUB,"\"","c","a","<","-","-","R","-",
   75     " ",SUB,"2","3","'","u","P",".",",","1","o",">",SUB,SUB,SUB,"?",
   76     "A","A","A","A","A","A","A","C","E","E","E","E","I","I","I","I",
   77     "D","N","O","O","O","O","O","x","O","U","U","U","U","Y","T","s",
   78     "a","a","a","a","a","a","a","c","e","e","e","e","i","i","i","i",
   79     "d","n","o","o","o","o","o",":","o","u","u","u","u","y","t","y"
   80     },
   81     /* table for Danish, Dutch, German, Norwegian and Swedish */
   82     {
   83     " ","!","c",SUB,SUB,"Y","|",SUB,"\"","(c)","a","<<","-","-","(R)","-",
   84     " ","+/-","2","3","'","u","P",".",",","1","o",">>"," 1/4"," 1/2"," 3/4","?",
   85     "A","A","A","A","Ae","Aa","AE","C","E","E","E","E","I","I","I","I",
   86     "D","N","O","O","O","O","Oe","x","Oe","U","U","U","Ue","Y","Th","ss",
   87     "a","a","a","a","ae","aa","ae","c","e","e","e","e","i","i","i","i",
   88     "d","n","o","o","o","o","oe",":","oe","u","u","u","ue","y","th","ij"
   89     },
   90     /* table for Danish, Finnish, Norwegian and Swedish, ISO 646 variant */
   91     {
   92     " ","!","c",SUB,"$","Y","|",SUB,"\"","(c)","a","<<","-","-","(R)","-",
   93     " ","+/-","2","3","'","u","P",".",",","1","o",">>"," 1/4"," 1/2"," 3/4","?",
   94     "A","A","A","A","[","]","[","C","E","@","E","E","I","I","I","I",
   95     "D","N","O","O","O","O","\\","x","\\","U","U","U","^","Y","Th","ss",
   96     "a","a","a","a","{","}","{","c","e","`","e","e","i","i","i","i",
   97     "d","n","o","o","o","o","|",":","|","u","u","u","~","y","th","y"
   98     },
   99     /* table with RFC1345 codes in brackets */
  100     {
  101     "[NS]","[!I]","[Ct]","[Pd]","[Cu]","[Ye]","[BB]","[SE]",
  102     "[':]","[Co]","[-a]","[<<]","[NO]","[--]","[Rg]","['-]",
  103     "[DG]","[+-]","[2S]","[3S]","['']","[My]","[PI]","[.M]",
  104     "[',]","[1S]","[-o]","[>>]","[14]","[12]","[34]","[?I]",
  105     "[A!]","[A']","[A>]","[A?]","[A:]","[AA]","[AE]","[C,]",
  106     "[E!]","[E']","[E>]","[E:]","[I!]","[I']","[I>]","[I:]",
  107     "[D-]","[N?]","[O!]","[O']","[O>]","[O?]","[O:]","[*X]",
  108     "[O/]","[U!]","[U']","[U>]","[U:]","[Y']","[TH]","[ss]",
  109     "[a!]","[a']","[a>]","[a?]","[a:]","[aa]","[ae]","[c,]",
  110     "[e!]","[e']","[e>]","[e:]","[i!]","[i']","[i>]","[i:]",
  111     "[d-]","[n?]","[o!]","[o']","[o>]","[o?]","[o:]","[-:]",
  112     "[o/]","[u!]","[u']","[u>]","[u:]","[y']","[th]","[y:]"
  113     },
  114     /* table for printers that allow overstriking with backspace */
  115     {
  116     " ","!","c\b|","L\b-","o\bX","Y\b=","|",SUB,
  117     "\"","(c)","a\b_","<<","-\b,","-","(R)","-",
  118     " ","+\b_","2","3","'","u","P",".",
  119     ",","1","o\b_",">>"," 1/4"," 1/2"," 3/4","?",
  120     "A\b`","A\b'","A\b^","A\b~","A\b\"","Aa","AE","C\b,",
  121     "E\b`","E\b'","E\b^","E\b\"","I\b`","I\b'","I\b^","I\b\"",
  122     "D\b-","N\b~","O\b`","O\b'","O\b^","O\b~","O\b\"","x",
  123     "O\b/","U\b`","U\b'","U\b^","U\b\"","Y\b'","Th","ss",
  124     "a\b`","a\b'","a\b^","a\b~","a\b\"","aa","ae","c\b,",
  125     "e\b`","e\b'","e\b^","e\b\"","i\b`","i\b'","i\b^","i\b\"",
  126     "d\b-","n\b~","o\b`","o\b'","o\b^","o\b~","o\b\"","-\b:",
  127     "o\b/","u\b`","u\b'","u\b^","u\b\"","y\b'","th","y\b\""
  128     },
  129     /* table for IBM PC character set (code page 437) */
  130     {
  131     "\377","\255","\233","\234",SUB,"\235","|","\25",
  132     "\"","(c)","\246","\256","\252","-","(R)","-",
  133     "\370","\361","\375","3","'","\346","\24","\371",
  134     ",","1","\247","\257","\254","\253"," 3/4","\250",
  135     "A","A","A","A","\216","\217","\222","\200",
  136     "E","\220","E","E","I","I","I","I",
  137     "D","\245","O","O","O","O","\231","x",
  138     "\355","U","U","U","\232","Y","T","\341",
  139     "\205","\240","\203","a","\204","\206","\221","\207",
  140     "\212","\202","\210","\211","\215","\241","\214","\213",
  141     "d","\244","\225","\242","\223","o","\224","\366",
  142     "\355","\227","\243","\226","\201","y","t","\230"
  143     }
  144 };
  145 
  146 /*
  147  * German tex style to latin1 conversion (by root@aspic, 12/04/93)
  148  */
  149 
  150 #define TEX_SUBST   16
  151 #define SPACES      "                                                                                                         "
  152 
  153 static const char *const tex_from[TEX_SUBST] =
  154 {
  155     "\"a", "\\\"a",
  156     "\"o", "\\\"o",
  157     "\"u", "\\\"u",
  158     "\"A", "\\\"A",
  159     "\"O", "\\\"O",
  160     "\"U", "\\\"U",
  161     "\"s", "\\\"s", "\\3",
  162     NULL
  163 };
  164 
  165 /*
  166  *  Now the conversion function...
  167  */
  168 
  169 void
  170 convert_iso2asc(
  171     char *iso,
  172     char **asc_buffer,
  173     size_t *max_line_len,
  174     int t)
  175 {
  176     constext *p;
  177     constext *const *tab;
  178     char *asc;
  179     t_bool first;   /* flag for first SPACE/TAB after other characters */
  180     int i, a;   /* column counters in iso and asc */
  181 
  182     asc = *asc_buffer;
  183 
  184     if (iso == NULL || asc == NULL)
  185         return;
  186 
  187     tab = iso2asc[t];
  188     first = TRUE;
  189     i = a = 0;
  190     while (*iso != '\0') {
  191         if (*EIGHT_BIT(iso) >= ISO_EXTRA) {
  192             p = tab[*EIGHT_BIT(iso) - ISO_EXTRA];
  193             iso++;
  194             i++;
  195             first = TRUE;
  196             while (*p) {
  197                 *(asc++) = *(p++);
  198                 if ((asc - *asc_buffer) >= (int) *max_line_len) {
  199                     int offset = (int) (asc - *asc_buffer);
  200                     *max_line_len += 64;
  201                     *asc_buffer = my_realloc(*asc_buffer, *max_line_len);
  202                     asc = *asc_buffer + offset;
  203                 }
  204                 a++;
  205             }
  206         } else {
  207             if (a > i && ((*iso == ' ') || (*iso == '\t'))) {
  208                 /*
  209                  * spaces or TABS should be removed
  210                  */
  211                 if (*iso == ' ') {
  212                     /*
  213                      * only the first space after a letter must not be removed
  214                      */
  215                     if (first) {
  216                         *(asc++) = ' ';
  217                         a++;
  218                         first = FALSE;
  219                     }
  220                     i++;
  221                 } else {    /* here: *iso == '\t' */
  222                     if (a >= TABSTOP(i)) {
  223                         /*
  224                          * remove TAB or replace it with SPACE if necessary
  225                          */
  226                         if (first) {
  227                             *(asc++) = ' ';
  228                             a++;
  229                             first = FALSE;
  230                         }
  231                     } else {
  232                         /*
  233                          * TAB will correct the column difference
  234                          */
  235                         *(asc++) = '\t';    /* = *iso */
  236                         a = TABSTOP(a); /* = TABSTOP(i), because i < a < TABSTOP(i) */
  237                     }
  238                     i = TABSTOP(i);
  239                 }
  240                 iso++;
  241             } else {
  242                 /*
  243                  * just copy the characters and advance the column counters
  244                  */
  245                 if (*iso == '\t') {
  246                     a = i = TABSTOP(i); /* = TABSTOP(a), because here a = i */
  247                 } else if (*iso == '\b') {
  248                     a--;
  249                     i--;
  250                 } else {
  251                     a++;
  252                     i++;
  253                 }
  254                 *(asc++) = *(iso++);
  255                 first = TRUE;
  256             }
  257         }
  258         if ((asc - *asc_buffer) >= (int) *max_line_len) {
  259             int offset = (int) (asc - *asc_buffer);
  260             *max_line_len += 64;
  261             *asc_buffer = my_realloc(*asc_buffer, *max_line_len);
  262             asc = *asc_buffer + offset;
  263         }
  264     }
  265     *asc = '\0';
  266 }
  267 
  268 
  269 void
  270 convert_tex2iso(
  271     char *from,
  272     char *to)
  273 {
  274     const char *tex_to[TEX_SUBST];
  275     int i;
  276     size_t spaces = 0; /* spaces to add */
  277     size_t len, col = 0;    /* length of from, col counter */
  278     size_t subst_len;
  279     t_bool ex;
  280 
  281     /* initialize tex_to */
  282     memset(tex_to, '\0', sizeof(tex_to));
  283 
  284     /*
  285      * Charsets which have German umlauts incl. sharp s at the same
  286      * code position as ISO-8859-1
  287      * DEC-MCS, Windows-1252
  288      */
  289     if (IS_LOCAL_CHARSET("ISO-8859-1") ||
  290         IS_LOCAL_CHARSET("ISO-8859-2") ||
  291         IS_LOCAL_CHARSET("ISO-8859-3") ||
  292         IS_LOCAL_CHARSET("ISO-8859-4") ||
  293         IS_LOCAL_CHARSET("ISO-8859-9") ||
  294         IS_LOCAL_CHARSET("ISO-8859-10") ||
  295         IS_LOCAL_CHARSET("ISO-8859-13") ||
  296         IS_LOCAL_CHARSET("ISO-8859-14") ||
  297         IS_LOCAL_CHARSET("ISO-8859-15") ||
  298         IS_LOCAL_CHARSET("ISO-8859-16") ||
  299         iso2asc_supported >= 0) {
  300         tex_to[1] = tex_to[0] = "\344"; /* auml */
  301         tex_to[3] = tex_to[2] = "\366"; /* ouml */
  302         tex_to[5] = tex_to[4] = "\374"; /* uuml */
  303         tex_to[7] = tex_to[6] = "\304"; /* Auml */
  304         tex_to[9] = tex_to[8] = "\326"; /* Ouml */
  305         tex_to[11] = tex_to[10] = "\334";   /* Uuml */
  306         tex_to[14] = tex_to[13] = tex_to[12] = "\337"; /* szlig */
  307     } else if (IS_LOCAL_CHARSET("UTF-8")) { /* locale charset is UTF-8 */
  308         tex_to[1] = tex_to[0] = "\303\244"; /* auml */
  309         tex_to[3] = tex_to[2] = "\303\266"; /* ouml */
  310         tex_to[5] = tex_to[4] = "\303\274"; /* uuml */
  311         tex_to[7] = tex_to[6] = "\303\204"; /* Auml */
  312         tex_to[9] = tex_to[8] = "\303\226"; /* Ouml */
  313         tex_to[11] = tex_to[10] = "\303\234";   /* Uuml */
  314         tex_to[14] = tex_to[13] = tex_to[12] = "\303\237";  /* szlig */
  315     } else {
  316         strcpy(to, from);
  317         return;
  318     }
  319 
  320     *to = '\0';
  321     len = strlen(from);
  322 
  323     while (col < len) {
  324         i = 0;
  325         ex = FALSE;
  326         while ((i < TEX_SUBST - 1) && !ex) {
  327             subst_len = strlen(tex_from[i]);
  328             if (!strncmp(from + col, tex_from[i], subst_len)) {
  329                 strcat(to, tex_to[i]);
  330                 spaces += subst_len - strlen(tex_to[i]);
  331                 col += subst_len - 1;
  332                 ex = TRUE;
  333             }
  334             i++;
  335         }
  336         if (!ex)
  337             strncat(to, from + col, 1);
  338         if (from[col] == ' ') {
  339             strncat(to, SPACES, spaces);
  340             spaces = 0;
  341         }
  342 
  343         col++;
  344     }
  345 }
  346 
  347 
  348 /*
  349  * Check for German TeX encoding in file open on fp
  350  */
  351 t_bool
  352 is_art_tex_encoded(
  353     FILE *fp)
  354 {
  355     char line[LEN];
  356     int i, len;
  357     t_bool body = FALSE;
  358 
  359     rewind(fp);
  360 
  361     while (fgets(line, (int) sizeof(line), fp) != NULL) {
  362         if (line[0] == '\n' && !body)
  363             body = TRUE;
  364         else if (!body)
  365             continue;
  366 
  367         i = 0;
  368 
  369         while (line[i++] == ' ')
  370             ;   /* search for first non blank */
  371 
  372         i--;
  373 
  374         if (!isalnum((unsigned char) line[i]) && line[i] != '\"')
  375             continue;   /* quoting char */
  376 
  377         len = (int) strlen(line) - 1;
  378         for (i = 1; i < len; i++) {
  379             if (((line[i] == '\\') || (line[i] == '\"')) &&
  380                             (isalnum((unsigned char) line[i - 1])) &&
  381                             (isalnum((unsigned char) line[i + 1])))
  382                 return TRUE;
  383         }
  384     }
  385 
  386     return FALSE;
  387 }
  388 
  389 
  390 /*
  391  * Replace all non printable characters by '?'
  392  */
  393 char *
  394 convert_to_printable(
  395     char *buf,
  396     t_bool keep_tab)
  397 {
  398 #if defined(MULTIBYTE_ABLE) && !defined(NO_LOCALE)
  399     char *buffer;
  400     wchar_t *wbuffer;
  401     size_t len = strlen(buf) + 1;
  402 
  403     if (IS_LOCAL_CHARSET("UTF-8"))
  404         utf8_valid(buf);
  405 
  406     if ((wbuffer = char2wchar_t(buf)) != NULL) {
  407         wconvert_to_printable(wbuffer, keep_tab);
  408 
  409         if ((buffer = wchar_t2char(wbuffer)) != NULL) {
  410             strncpy(buf, buffer, len);
  411             buf[len - 1] = '\0';
  412 
  413             free(buffer);
  414         }
  415         free(wbuffer);
  416     }
  417 #else
  418     unsigned char *c;
  419 
  420     for (c = (unsigned char *) buf; *c; c++) {
  421         if (!my_isprint(*c) && !(keep_tab && *c == '\t'))
  422             *c = '?';
  423     }
  424 #endif /* MULTIBYTE_ABLE && !NO_LOCALE */
  425     return buf;
  426 }
  427 
  428 
  429 #if defined(MULTIBYTE_ABLE) && !defined(NO_LOCALE)
  430 /*
  431  * NOTES: don't make wc a wint_t as libutf8 (at least version 0.8)
  432  *        sometimes fails to proper convert (wchar_t) 0 to (wint_t) 0
  433  *        and thus loop termination fails.
  434  */
  435 wchar_t *
  436 wconvert_to_printable(
  437     wchar_t *wbuf,
  438     t_bool keep_tab)
  439 {
  440     wchar_t *wc;
  441 
  442     for (wc = wbuf; *wc; wc++) {
  443         if (!iswprint((wint_t) *wc) && !(keep_tab && *wc == (wchar_t) '\t'))
  444             *wc = (wchar_t) '?';
  445     }
  446 
  447     return wbuf;
  448 }
  449 #endif /* MULTIBYTE_ABLE && !NO_LOCALE */