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1 /*****************************************************************************
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2
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3 NAME
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4 clc-cset.c -- CLC-INTERCAL character set support for C-INTERCAL
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5
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6 LICENSE TERMS
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7 Copyright (C) 2007 Alex Smith
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8
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9 This program is free software; you can redistribute it and/or modify
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10 it under the terms of the GNU General Public License as published by
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11 the Free Software Foundation; either version 2 of the License, or
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12 (at your option) any later version.
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13
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14 This program is distributed in the hope that it will be useful,
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15 but WITHOUT ANY WARRANTY; without even the implied warranty of
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16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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17 GNU General Public License for more details.
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18
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19 You should have received a copy of the GNU General Public License
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20 along with this program; if not, write to the Free Software
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21 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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22
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23 ***************************************************************************/
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24
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25 /*
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26 The input is read from files such as latin1.bin and ebcdic.bin.
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27 These contain three lines of text data that specify the length of
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28 the character set (number of characters in each shift state), the
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29 number of shift states, and the bit order of the input. The bit
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30 order can either be 8 characters long (msb down to lsb) or 16 (the
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31 ick_first byte in a pair, followed by the second); each bit of the input
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32 is transferred to the corresponding bit in a binary table that
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33 follows (a for the lsb, b for the second least significant bit, up
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34 to l for the 12th least significant bit; at most 12 significant bits
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35 are allowed), or x for a don't care on the bit. The table that
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36 follows is the relevant character codes in Latin-1 (which is used as
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37 the interconversion language); if shift states are used, they're
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38 represented by character codes 1, 2, 3, etc.. Invalid characters are
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39 represented by character code 0, and changed to nulls on output. The
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40 order of the bytes is 'Latin-1 for this set's char 0 in shift state
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41 1', 'Latin-1 for this set's char 0 in shift state 2', ..., 'Latin-1
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42 for this set's char 1 in shift state 1', and so on.
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43
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44 Note that as the character set feature is designed to mirror
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45 CLC-INTERCAL's, I've sprinkled a bit of idiomatic Perl throughout
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46 the code. This is quite rare, though, as it has to be also legal in C.
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47 */
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48
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49 #include <stdio.h>
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50 #include <string.h>
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51 #include <stdlib.h>
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52 #include "uncommon.h"
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53 #define NCSETRECENT 8
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54
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55 /* Sometimes we want to link the character set files to the program
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56 * rather than reading them from disk; in this case, these extern
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57 * variables will be set non-null by object files invented
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58 * specifically for the purpose. */
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59 extern /*@null@*/ const char* ick_clc_cset_atari;
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60 extern /*@null@*/ const char* ick_clc_cset_baudot;
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61 extern /*@null@*/ const char* ick_clc_cset_ebcdic;
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62 extern /*@null@*/ const char* ick_clc_cset_latin1;
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63
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64 static /*@null@*/ const char* ick_clc_cset_ptr=0;
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65
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66 /* Fake that we're reading hardcoded characters from a file. This
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67 * method of doing it is obviously not thread-safe. */
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68 static int ick_clc_cset_hardcoderead(FILE* ignored)
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69 {
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70 /*@-noeffect@*/
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71 (void) ignored;
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72 /*@=noeffect@*/
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73 return (int)*ick_clc_cset_ptr++;
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74 }
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75
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76 struct cset
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77 {
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78 unsigned char set[4096]; /* allow up to 12 bits of data+shifts */
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79 unsigned short setlen;
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80 int shifts;
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81 char setname[9]; /* 8.3 filenames are enforced! */
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82 char bitorder[16];
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83 int nbytes;
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84 };
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85
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86 /* In particular, this initialises the setnames to the null string,
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87 * and clears nbytes. Both of these are used to determine whether a
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88 * cset is valid or not. */
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89 /*@-initallelements@*/ /*@-type@*/
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90 static struct cset ick_cset_recent[NCSETRECENT]={{{0},0,0,{0},{0},0}};
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91 /*@=initallelements@*/ /*@=type@*/
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92 static int ick_csetow=0; /* which cset to overwrite ick_next */
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93
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94 /* For help finding files */
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95 /*@observer@*/ extern char* ick_globalargv0;
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96 /*@observer@*/ extern const char* ick_datadir;
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97
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98 /*@-mustfreefresh@*/
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99 /* because Splint doesn't understand how findandfopen works */
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100 static void ick_clc_cset_load(/*@unique@*/ struct cset* cs, /*@unique@*/ const char* fname)
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101 {
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102 FILE* in;
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103 char buf[13]; /* enough for an 8.3 filename */
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104 int i,j,c;
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105 int (*ipf)(FILE*);
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106 /* Avoid buffer-overflow attacks. */
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107 if(strlen(fname)>8) return;
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108 /* If ick_clc_cset_atari is non-null, then don't read from disk. */
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109 if(ick_clc_cset_atari)
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110 {
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111 /* If the character sets have been hardcoded, only accept
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112 * hardcoded chararacter sets. */
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113 ick_clc_cset_ptr=0;
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114 if(!strcmp(fname,"atari")) ick_clc_cset_ptr=ick_clc_cset_atari;
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115 if(!strcmp(fname,"baudot")) ick_clc_cset_ptr=ick_clc_cset_baudot;
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116 if(!strcmp(fname,"ebcdic")) ick_clc_cset_ptr=ick_clc_cset_ebcdic;
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117 if(!strcmp(fname,"latin1")) ick_clc_cset_ptr=ick_clc_cset_latin1;
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118 if(!ick_clc_cset_ptr) return; /* not a hardcoded charset */
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119 in=(FILE*)0;
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120 ipf=ick_clc_cset_hardcoderead;
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121 }
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122 else
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123 {
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124 /* We already checked above that this isn't a buffer overflow. */
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125 /*@-bufferoverflowhigh@*/
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126 sprintf(buf,"%s.bin",fname);
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127 /*@=bufferoverflowhigh@*/
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128 if(!(in=ick_findandfopen(buf,ick_datadir,"rb",ick_globalargv0))) return;
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129 ipf=fgetc;
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130 }
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131 /* First row: setlen */
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132 cs->setlen=0;
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133 do
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134 {
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135 /* The input is definitely in ASCII, even if the C program isn't,
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136 which is why numeric codes are used. */
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137 /* Here, ipf allows NULL input iff in is actually NULL; this situation
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138 is impossible to explain with an annotation, so instead just disable
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139 the warning. */
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140 /*@-nullpass@*/
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141 c=ipf(in);
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142 /*@=nullpass@*/
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143 if(c==EOF) {if(in) (void)fclose(in); return;}
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144 if(c<48||c>57) break;
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145 cs->setlen*=10;
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146 cs->setlen+=c-48;
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147 } while(1);
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148 if(c!=10) {if(in) (void)fclose(in); return;}
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149 /* Second row: shifts. This can be from 1 to 9. */
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150 /*@-nullpass@*/
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151 c=ipf(in);
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152 /*@=nullpass@*/
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153 if(c<49||c>57) {if(in) (void)fclose(in); return;}
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154 cs->shifts=c-48;
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155 /*@-nullpass@*/
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156 if(ipf(in)!=10) {if(in) (void)fclose(in); return;}
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157 /*@=nullpass@*/
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158 /* Third row: byte order. */
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159 i=0;
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160 /*@-nullpass@*/
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161 while(((c=ipf(in)))>96&&i<16) cs->bitorder[i++]=(char)c;
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162 /*@=nullpass@*/
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163 /* Sanity check; that it is a whole number of bytes, that the input
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164 * format is correct, and that there are at most 4096 bytes of data
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165 * total. */
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166 if(c!=10||i%8||!i||cs->setlen*cs->shifts>4096) return;
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167 /* i/8 is now the number of bytes, but don't set that yet in case
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168 * there's an error later. */
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169 /* Rest of file: the bytes themselves. */
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170 j=0;
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171 /*@-nullpass@*/
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172 while(j<cs->setlen*cs->shifts)
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173 if((cs->set[j++]=(unsigned char)(c=ipf(in))),c==EOF && in != NULL)
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174 {if(in) (void)fclose(in); return;}
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175 /*@=nullpass@*/
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176 if(in) (void) fclose(in);
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177 /* Now set the name and number of bytes, indicating a successful
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178 * load. */
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179 cs->nbytes=i/8;
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180 strcpy(cs->setname,fname);
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181 }
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182 /*@=mustfreefresh@*/
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183
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184 /* Helper function for fixing bit order in output. */
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185 static void ick_bitencout(char** pop, const struct cset* co,
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186 unsigned short val, int padstyle)
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187 {
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188 unsigned short outword=0;
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189 int i=co->nbytes*8;
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190 /*@-shiftnegative@*/ /* i can't go above it's initial value here */
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191 while(i--)
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192 if(co->bitorder[i]>'l')
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193 {
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194 if((padstyle==1&&(i==1||i==9) && !(outword&(1<<(co->nbytes*8-i)))) ||
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195 (padstyle==2&&(rand()%2||!outword)))
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196 outword |= 1<<(co->nbytes*8-i-1);
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197 }
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198 /* Copy the appropriate bit from val to outword. */
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199 else outword |= (unsigned short)((val>>(co->bitorder[i]-'a'))&1)
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200 << (co->nbytes*8-i-1);
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201 /*@=shiftnegative@*/
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202 if(co->nbytes==2) *(*pop)++=(char)(outword/256);
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203 *(*pop)++=(char)(outword%256);
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204 }
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205
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206 /* padstyle is 0 to pad with zeros, 1 to pad to make the output
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207 * printable characters, or 2 to pad with garbage, avoiding 0s.
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208 * Return value is the number of characters in the output string,
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209 * which may contain embedded NULs if the input contained invalid
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210 * characters. Returns -1 on error. The caller is responsible for
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211 * making sure that out is big enough, but as a check, no more than
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212 * outsize-1 characters and a NUL will be written to out. The code is
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213 * conservative about this; to be safe, make outsize six times as long
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214 * as the in is (including in's terminal NUL), plus 6. */
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215 int ick_clc_cset_convert(const char* in, /*@partial@*/ char* out, const char* incset,
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216 const char* outcset, int padstyle, size_t outsize,
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217 /*@null@*/ FILE* errsto)
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218 {
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219 int ic=-1, oc=-1;
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220 int i;
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221 int ssi, sso;
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222 unsigned short tus, csi;
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223 const char* ip;
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224 char* op;
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225 struct cset *csri, *csro;
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226 int noconvwarn=0;
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227 int substwarn=0;
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228 /* First, see if we have a recently-used version of incset or outcset. */
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229 i=NCSETRECENT;
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230 while(i--)
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231 {
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232 (void)(strcmp(incset,ick_cset_recent[i].setname) || (ic=i));
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233 (void)(strcmp(outcset,ick_cset_recent[i].setname) || (oc=i));
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234 }
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235 /* Find a blank entry to load on top of. */
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236 if(ic==-1) for(i=NCSETRECENT;i--;) if(!ick_cset_recent[i].nbytes) ic=i;
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237 if(oc==-1) for(i=NCSETRECENT;i--;) if(!ick_cset_recent[i].nbytes&&i!=ic) oc=i;
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238 /* Failing that, find any entry to load on top of. */
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239 (void)(ic==-1 && (ick_cset_recent[ic=ick_csetow++].nbytes=0));
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240 if(ick_csetow==ic) ick_csetow++;
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241 ick_csetow%=NCSETRECENT;
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242 (void)(oc==-1 && (ick_cset_recent[oc=ick_csetow++].nbytes=0));
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243 ick_csetow%=NCSETRECENT;
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244 /* If the character set hasn't been loaded, load it now. */
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245 ick_cset_recent[ic].nbytes || (ick_clc_cset_load(ick_cset_recent+ic,incset),0);
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246 ick_cset_recent[oc].nbytes || (ick_clc_cset_load(ick_cset_recent+oc,outcset),0);
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247 csri=ick_cset_recent+ic;
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248 csro=ick_cset_recent+oc;
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249 /* If a character set failed to load, bail out. */
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250 if(!csri->nbytes)
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251 {
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252 if(errsto) fprintf(errsto,"Error: Nonexistent input character set.\n");
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253 return -1;
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254 }
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255 if(!csro->nbytes)
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256 {
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257 if(errsto) fprintf(errsto,"Error: Nonexistent output character set.\n");
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258 return -1;
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259 }
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260 /* There is no initial shift state. */
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261 ssi=sso=0;
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262 csri->shifts==1 && (ssi=1);
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263 csro->shifts==1 && (sso=1);
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264 ip=in; op=out;
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265 while(*ip != '\0' && (size_t)(op-out)<outsize-6)
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266 {
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267 tus=(unsigned short)(unsigned char)*ip++;
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268 if(csri->nbytes==2)
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269 {
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270 tus*=256;
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271 tus+=(unsigned short)(unsigned char)*ip++;
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272 }
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273 i=csri->nbytes*8;
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274 csi=0;
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275 while(i--)
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276 {
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277 if(csri->bitorder[i]>'l') continue;
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278 /* Copy the appropriate bit from tus to csi. */
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279 /*@-shiftnegative@*/
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280 csi |= (unsigned short)((tus>>(csri->nbytes*8-i-1))&1)
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281 << (csri->bitorder[i]-'a');
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282 /*@=shiftnegative@*/
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283 }
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284 if(csi>csri->setlen)
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285 {
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286 ick_bitencout(&op,csro,0,padstyle); /* not in the charset */
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287 if(!noconvwarn && errsto != NULL)
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288 fprintf(errsto,"Warning: some characters could not be translated,"
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289 " they were replaced with NUL.\n");
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290 noconvwarn=1;
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291 }
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292 else
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293 {
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294 /* The more interesting case. */
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295 csi*=csri->shifts;
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296 if(!ssi)
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297 {
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298 /* We're at the start of a shift-stated string, but not
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299 actually in any shift state. There is no general solution
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300 here, so use one that works for Baudot: starting in each
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301 state in turn, choose the option that takes the longest
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302 until it ends up not changing shift state, then perform one
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303 shift from that option. */
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304 int sstesting, ssbestsf, ssrecord, j, k;
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305 sstesting=csri->shifts+1; ssbestsf=ssrecord=0;
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306 while(--sstesting)
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307 {
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308 k=sstesting; j=0;
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309 while(csri->set[csi+i-1] != (unsigned char)0 &&
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310 (int)csri->set[csi+i-1]!=k &&
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311 (int)csri->set[csi+i-1]<=csri->shifts)
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312 {k=(int)csri->set[csi+i-1]; j++;}
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313 if(ssbestsf<j) {ssbestsf=sstesting; ssrecord=j;}
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314 }
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315 ssi=ssbestsf;
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316 }
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317 csi+=ssi-1;
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318 tus=(unsigned short)csri->set[csi]; /* we now have the Latin-1 conversion! */
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319 if(tus>=1&&tus<=(unsigned short)csri->shifts&&csri->shifts>1)
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320 {
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321 /* That wasn't a character, but a shift command. */
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322 ssi=(int)tus;
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323 continue;
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324 }
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325 /* Look for the character in the output's character
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326 * set. Preferably we want something in the current shift
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327 * state, but failing that, any character will do. */
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328 spacenowtab:
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329 i=csro->shifts*csro->setlen;
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330 csi=10000;
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331 while(i--)
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332 (void)((unsigned short)csro->set[i]==tus &&
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333 (csi==10000 || (int)csi%csro->shifts!=sso-1) &&
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334 (csi=(unsigned short)i));
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335 if(csi==10000&&tus==9 /* latin-1 tab */)
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336 {
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337 if(!substwarn && errsto != NULL)
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338 fprintf(errsto,"Warning: no tab in output character set,"
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339 " space was used instead.\n");
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340 substwarn=1;
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341 tus=32; /* latin-1 space */
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342 goto spacenowtab;
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343 }
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344 if(csi==10000)
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345 {
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346 ick_bitencout(&op,csro,0,padstyle); /* not in the charset */
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347 if(!noconvwarn && errsto != NULL)
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348 fprintf(errsto,"Warning: some characters could not be translated,"
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349 " they were replaced with NUL.\n");
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350 noconvwarn=1;
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351 }
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352 else if((int)(csi%csro->shifts)==(int)sso-1)
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353 /* in the right shift state already */
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354 ick_bitencout(&op,csro,(unsigned short)(csi/csro->shifts),padstyle);
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355 else
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356 {
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357 int tempi;
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358 /* Generate shift codes. If sso isn't 0, generate from where
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359 * we are at the moment; if it is 0, generate worse-case
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360 * shifts by assuming we're in a shift state that can't shift
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361 * to the state we want directly, if possible. */
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362 if(!sso)
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363 {
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364 int j=csro->shifts+1;
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365 while(--j>0)
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366 {
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367 if(j-1==(int)(csi%csro->shifts)) continue;
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368 i=(int)csro->setlen;
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369 while(i--)
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370 if((int)csro->set[i*csro->shifts+j-1]==csi%csro->shifts+1)
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371 {j=-j; break; /* there is one in this set */};
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372 j=-j;
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373 if(j<0) break;
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374 }
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375 /* Pick the worst-case if we found one, or otherwise just
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376 * any state we aren't in at the moment. */
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377 sso=(j<0?-j:(int)(csi%csro->shifts));
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378 if(!sso) sso=csro->shifts;
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379 }
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380 /* Look for the shift code, if there is one. */
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381 i=(int)csro->setlen;
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382 while(i--)
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383 if((int)csro->set[i*csro->shifts+sso-1]==csi%csro->shifts+1) break;
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384 tempi=i*csro->shifts+sso-1;
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385 if(i==-1)
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386 {
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387 int intershift=-1;
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388 /* That didn't work. Look for the shift code in some shift
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389 * state other than the one we're aiming for. */
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390 retry:
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391 i=csro->setlen*csro->shifts;
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392 while(i--)
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393 if((int)csro->set[i]==csi%csro->shifts+1&&
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394 i%csro->shifts!=(int)(csi%csro->shifts)&&
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395 i%csro->shifts+1!=intershift) break;
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396 if(i==-1) return -1; /* no way to get into the right state */
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397 intershift=i%csro->shifts+1;
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|
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398 tempi=i;
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|
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399 i=(int)csro->setlen;
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|
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400 while(i--)
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401 if((int)csro->set[i*csro->shifts+sso-1]==intershift) break;
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|
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402 if(i==-1) goto retry; /* try once more */
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|
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403 ick_bitencout(&op,csro,(unsigned short)i,padstyle);
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404 /* sso=intershift here but we're going to overwrite it
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|
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405 * immediately anyway, so no point in the assignment */
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|
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406 }
|
|
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407 ick_bitencout(&op,csro,(unsigned short)(tempi/csro->shifts),padstyle);
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|
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408 ick_bitencout(&op,csro,(unsigned short)(csi/csro->shifts),padstyle);
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|
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409 sso=csi%csro->shifts+1;
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|
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410 }
|
|
|
411 }
|
|
|
412 }
|
|
|
413 *op='\0';
|
|
|
414 return op-out;
|
|
|
415 }
|
