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292
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1 /*
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2 lwcc/cpp/file.c
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3
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4 Copyright © 2013 William Astle
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5
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6 This file is part of LWTOOLS.
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7
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8 LWTOOLS is free software: you can redistribute it and/or modify it under the
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9 terms of the GNU General Public License as published by the Free Software
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10 Foundation, either version 3 of the License, or (at your option) any later
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11 version.
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12
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13 This program is distributed in the hope that it will be useful, but WITHOUT
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14 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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16 more details.
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17
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18 You should have received a copy of the GNU General Public License along with
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19 this program. If not, see <http://www.gnu.org/licenses/>.
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20
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21
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22 NOTES:
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23
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24 The function fetch_byte() grabs a byte from the input file. It returns
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25 CPP_EOF if end of file has been reached. The resulting byte has passed
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26 through three filters, in order:
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27
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28 * All CRLF, LFCR, LF, and CR have been converted to CPP_EOL
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29 * If enabled (--trigraphs), trigraphs have been interpreted
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30 * \\n (backslash-newline) has been processed (eliminated)
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31
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32 To obtain a byte without processing \\n, call fetch_byte_tg().
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33
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34 */
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35
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36 #include <errno.h>
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37 #include <stdio.h>
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38 #include <string.h>
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39
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40 #include <lw_alloc.h>
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41
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42 #include "cpp.h"
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43
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44 struct file_stack_e *file_stack = NULL;
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45
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46 int is_whitespace(int c)
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47 {
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48 switch (c)
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49 {
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50 case ' ':
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51 case '\t':
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52 case '\r':
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53 case '\n':
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54 return 1;
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55 }
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56 return 0;
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57 }
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58
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59 int is_sidchr(c)
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60 {
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61 if (c == '_' || (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z'))
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62 return 1;
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63 return 0;
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64 }
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65
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66 int is_idchr(int c)
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67 {
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68 if (c >= '0' && c <= '9')
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69 return 1;
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70 return is_sidchr(c);
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71 }
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72
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73 int is_ep(int c)
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74 {
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75 if (c == 'e' || c == 'E' || c == 'p' || c == 'P')
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76 return 1;
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77 return 0;
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78 }
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79
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80 int is_hex(int c)
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81 {
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82 if (c >= 'a' && c <= 'f')
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83 return 1;
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84 if (c >= 'A' && c <= 'F')
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85 return 1;
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86 if (c >= '0' && c <= '9')
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87 return 1;
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88 return 0;
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89 }
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90
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91 int is_dec(int c)
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92 {
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93 if (c >= '0' && c <= '9')
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94 return 1;
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95 return 0;
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96 }
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97
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98 static void outchr(int c)
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99 {
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100 fputc(c, output_fp);
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101 }
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102
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103 static void outstr(char *s)
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104 {
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105 while (*s)
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106 outchr(*s++);
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107 }
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108
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109 int fetch_byte_ll(struct file_stack_e *f)
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110 {
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111 int c;
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112
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113 if (f -> eolstate != 0)
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114 {
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115 f -> line++;
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116 f -> col = 0;
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117 }
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118 c = getc(f -> fp);
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119 f -> col++;
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120 if (f -> eolstate == 1)
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121 {
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122 // just saw CR, munch LF
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123 if (c == 10)
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124 c = getc(f -> fp);
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125 f -> eolstate = 0;
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126 }
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127 else if (f -> eolstate == 2)
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128 {
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129 // just saw LF, much CR
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130 if (c == 13)
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131 c = getc(f -> fp);
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132 f -> eolstate = 0;
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133 }
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134
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135 if (c == 10)
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136 {
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137 // we have LF - end of line, flag to munch CR
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138 f -> eolstate = 2;
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139 c = CPP_EOL;
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140 }
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141 else if (c == 13)
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142 {
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143 // we have CR - end of line, flag to munch LF
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144 f -> eolstate = 1;
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145 c = CPP_EOL;
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146 }
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147 else if (c == EOF)
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148 {
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149 c = CPP_EOF;
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150 }
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151 return c;
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152 }
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153
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154 int fetch_byte_tg(struct file_stack_e *f)
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155 {
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156 int c;
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157
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158 if (!trigraphs)
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159 {
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160 c = fetch_byte_ll(f);
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161 }
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162 else
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163 {
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164 /* we have to do the trigraph shit here */
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165 if (f -> ra != CPP_NOUNG)
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166 {
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167 if (f -> qseen > 0)
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168 {
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169 c = '?';
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170 f -> qseen -= 1;
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171 return c;
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172 }
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173 else
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174 {
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175 c = f -> ra;
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176 f -> ra = CPP_NOUNG;
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177 return c;
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178 }
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179 }
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180
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181 c = fetch_byte_ll(f);
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182 while (c == '?')
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183 {
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184 f -> qseen++;
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185 c = fetch_byte_ll(f);
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186 }
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187
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188 if (f -> qseen >= 2)
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189 {
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190 // we have a trigraph
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191 switch (c)
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192 {
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193 case '=':
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194 c = '#';
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195 f -> qseen -= 2;
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196 break;
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197
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198 case '/':
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199 c = '\\';
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200 f -> qseen -= 2;
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201 break;
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202
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203 case '\'':
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204 c = '^';
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205 f -> qseen -= 2;
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206 break;
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207
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208 case '(':
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209 c = '[';
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210 f -> qseen -= 2;
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211 break;
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212
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213 case ')':
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214 c = ']';
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215 f -> qseen -= 2;
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216 break;
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217
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218 case '!':
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219 c = '|';
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220 f -> qseen -= 2;
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221 break;
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222
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223 case '<':
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224 c = '{';
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225 f -> qseen -= 2;
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226 break;
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227
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228 case '>':
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229 c = '}';
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230 f -> qseen -= 2;
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231 break;
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232
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233 case '~':
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234 c = '~';
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235 f -> qseen -= 2;
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236 break;
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237 }
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238 if (f -> qseen > 0)
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239 {
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240 f -> ra = c;
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241 c = '?';
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242 f -> qseen--;
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243 }
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244 }
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245 else if (f -> qseen > 0)
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246 {
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247 f -> ra = c;
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248 c = '?';
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249 f -> qseen--;
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250 }
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251 }
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252 return c;
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253 }
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254
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255 int fetch_byte(struct file_stack_e *f)
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256 {
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257 int c;
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258
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259 again:
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260 if (f -> unget != CPP_NOUNG)
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261 {
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262 c = f -> unget;
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263 f -> unget = CPP_NOUNG;
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264 }
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265 else
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266 {
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267 c = fetch_byte_tg(f);
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268 }
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269 if (c == '\\')
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270 {
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271 int c2;
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272 c2 = fetch_byte_tg(f);
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273 if (c2 == CPP_EOL)
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274 goto again;
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275 else
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276 f -> unget = c2;
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277 }
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278 f -> curc = c;
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279 return c;
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280 }
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281
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282 static void skip_line(struct file_stack_e *f)
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283 {
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284 int c;
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285 while ((c = fetch_byte(f)) != CPP_EOL && c != CPP_EOF)
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286 /* do nothing */ ;
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287 }
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288
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289
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290 struct
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291 {
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292 char *name;
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293 void (*fn)(struct file_stack_e *);
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294 } directives[] =
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295 {
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296 { NULL, NULL },
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297 { NULL, NULL }
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298 };
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299
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300 /*
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301 This handles a preprocessing directive. Such a directive goes from the
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302 next character to be retrieved from f until the first instance of CPP_EOL
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303 or CPP_EOF.
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304 */
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305 void handle_directive(struct file_stack_e *f)
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306 {
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307 int c, i;
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308 char kw[20];
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309
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310 again:
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311 while ((c = fetch_byte(f)) == ' ' || c == '\t')
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312 /* do nothing */ ;
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313 if (c == '/')
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314 {
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315 // maybe a comment //
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316 c = fetch_byte(f);
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317 if (c == '/')
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318 {
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319 // line comment
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320 skip_line(f);
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321 return;
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322 }
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323 if (c == '*')
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324 {
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325 // block comment
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326 while (1)
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327 {
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328 c = fetch_byte(f);
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329 if (c == CPP_EOF)
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330 return;
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331 if (c == '*')
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332 {
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333 c = fetch_byte(f);
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334 if (c == '/')
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335 {
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336 // end of comment - try again for directive
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337 goto again;
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338 }
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339 if (c == CPP_EOF)
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340 return;
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341 }
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342 }
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343 }
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344 }
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345
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346 // empty directive - do nothing
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347 if (c == CPP_EOL)
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348 return;
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349
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350 if (c < 'a' || c > 'z')
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351 goto out;
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352
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353 i = 0;
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354 do
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355 {
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356 kw[i++] = c;
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357 if (i == sizeof(kw) - 1)
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358 goto out; // keyword too long
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359 c = fetch_byte(f);
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360 } while ((c >= 'a' && c <= 'z') || (c == '_'));
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361 kw[i++] = '\0';
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362
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363 /* we have a keyword here */
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364 for (i = 0; directives[i].name; i++)
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365 {
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366 if (strcmp(directives[i].name, kw) == 0)
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367 {
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368 (*directives[i].fn)(f);
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369 return;
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370 }
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371 }
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372
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373 /* if we fall through here, we have an unknown directive */
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374 out:
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375 do_error("invalid preprocessor directive");
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376 skip_line(f);
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377 }
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378
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379 /*
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380 Notes:
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381
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382 Rather than tokenize the entire file, we run through it interpreting
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383 things only as much as we need to in order to identify the following:
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384
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385 preprocessing directives (#...)
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386 identifiers which might need to be replaced with macros
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387
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388 We have to interpret strings, character constants, and numbers to prevent
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389 false positives in those situations.
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390
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391 When we find a preprocessing directive, it is handled with a more
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392 aggressive tokenization process and then intepreted accordingly.
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393
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394 nlws is used to record the fact that only whitespace has occurred at the
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395 start of a line. Whitespace is defined as comments or isspace(c). It gets
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396 reset to 1 after each EOL character. If a non-whitespace character is
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397 encountered, it is set to -1. If the character processing decides it really
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398 is a whitespace character, it will set nlws back to 1 (block comment).
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399 Elsewise, it will get set to 0 if it is still -1 when the loop starts again.
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400
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401 This is needed so we can identify whitespace interposed before a
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402 preprocessor directive. This is the only case where it matters for
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403 the preprocessor.
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404
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405 */
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406 void preprocess_file(struct file_stack_e *f)
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407 {
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408 int c;
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409 int nlws = 1;
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410
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411 while (1)
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412 {
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413 c = fetch_byte(f);
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414 again:
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415 if (nlws == -1)
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416 nlws = 0;
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417 if (c == CPP_EOF)
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418 {
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419 outchr('\n');
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420 return;
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421 }
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422 if (c == CPP_EOL)
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423 {
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424 nlws = 1;
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425 outchr('\n');
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426 continue;
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427 }
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428
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429 if (!is_whitespace(c))
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430 nlws = -1;
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431
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432 if (is_sidchr(c))
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433 {
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434 // have identifier here - parse it off
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435 char *ident = NULL;
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436 int idlen = 0;
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437
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438 do
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439 {
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440 ident = lw_realloc(ident, idlen + 1);
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441 ident[idlen++] = c;
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442 ident[idlen] = '\0';
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443 c = fetch_byte(f);
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444 } while (is_idchr(c));
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445
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446 /* do something with the identifier here - macros, etc. */
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447 outstr(ident);
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448 lw_free(ident);
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449
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450 goto again;
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451 }
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452
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453 switch (c)
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454 {
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455 default:
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456 outchr(c);
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457 break;
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458
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459 case '.': // a number - to prevent seeing an identifier in middle of number
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460 outchr(c);
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461 c = fetch_byte(f);
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462 if (!is_dec(c))
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463 goto again;
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464 /* fall through */
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465 case '0':
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466 case '1':
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467 case '2':
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468 case '3':
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469 case '4':
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470 case '5':
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471 case '6':
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472 case '7':
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473 case '8':
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474 case '9':
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475 do
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476 {
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477 outchr(c);
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478 c = fetch_byte(f);
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479 if (c == CPP_EOF)
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480 return;
|
|
|
481 if (is_ep(c))
|
|
|
482 {
|
|
|
483 outchr(c);
|
|
|
484 c = fetch_byte(f);
|
|
|
485 if (c == '-' || c == '+')
|
|
|
486 {
|
|
|
487 outchr(c);
|
|
|
488 c = fetch_byte(f);
|
|
|
489 }
|
|
|
490 }
|
|
|
491 } while ((is_idchr(c)) || (c == '.'));
|
|
|
492 goto again;
|
|
|
493
|
|
|
494 case '#':
|
|
|
495 if (nlws)
|
|
|
496 {
|
|
|
497 handle_directive(f);
|
|
|
498 /* note: no need to reset nlws */
|
|
|
499 }
|
|
|
500 else
|
|
|
501 outchr('#');
|
|
|
502 break;
|
|
|
503
|
|
|
504 case '\'': // character constant
|
|
|
505 outchr('\'');
|
|
|
506 while ((c = fetch_byte(f)) != '\'')
|
|
|
507 {
|
|
|
508 if (c == '\\')
|
|
|
509 {
|
|
|
510 outchr('\\');
|
|
|
511 c = fetch_byte(f);
|
|
|
512 }
|
|
|
513 if (c == CPP_EOL)
|
|
|
514 {
|
|
|
515 do_warning("Unterminated character constant");
|
|
|
516 goto again;
|
|
|
517 }
|
|
|
518 if (c == CPP_EOF)
|
|
|
519 return;
|
|
|
520 outchr(c);
|
|
|
521 }
|
|
|
522 outchr(c);
|
|
|
523 break;
|
|
|
524
|
|
|
525 case '"': // strings
|
|
|
526 outchr(c);
|
|
|
527 while ((c = fetch_byte(f)) != '"')
|
|
|
528 {
|
|
|
529 if (c == '\\')
|
|
|
530 {
|
|
|
531 outchr('\\');
|
|
|
532 c = fetch_byte(f);
|
|
|
533 }
|
|
|
534 if (c == CPP_EOL)
|
|
|
535 {
|
|
|
536 do_warning("unterminated string literal");
|
|
|
537 goto again;
|
|
|
538 }
|
|
|
539 if (c == CPP_EOF)
|
|
|
540 return;
|
|
|
541 outchr(c);
|
|
|
542 }
|
|
|
543 outchr(c);
|
|
|
544 break;
|
|
|
545
|
|
|
546 case '/': // comments
|
|
|
547 c = fetch_byte(f);
|
|
|
548 if (c == '/')
|
|
|
549 {
|
|
|
550 // line comment
|
|
|
551 outchr(' ');
|
|
|
552 do
|
|
|
553 {
|
|
|
554 c = fetch_byte(f);
|
|
|
555 } while (c != CPP_EOF && c != CPP_EOL);
|
|
|
556 }
|
|
|
557 else if (c == '*')
|
|
|
558 {
|
|
|
559 // block comment
|
|
|
560 for (;;)
|
|
|
561 {
|
|
|
562 c = fetch_byte(f);
|
|
|
563 if (c == CPP_EOF)
|
|
|
564 {
|
|
|
565 break;
|
|
|
566 }
|
|
|
567 if (c == CPP_EOL)
|
|
|
568 {
|
|
|
569 continue;
|
|
|
570 }
|
|
|
571 if (c == '*')
|
|
|
572 {
|
|
|
573 // maybe end of comment
|
|
|
574 c = fetch_byte(f);
|
|
|
575 if (c == '/')
|
|
|
576 {
|
|
|
577 // end of comment
|
|
|
578 break;
|
|
|
579 }
|
|
|
580 }
|
|
|
581 }
|
|
|
582 // replace comment with a single space
|
|
|
583 outchr(' ');
|
|
|
584 if (nlws == -1)
|
|
|
585 nlws = 1;
|
|
|
586 continue;
|
|
|
587 }
|
|
|
588 else
|
|
|
589 {
|
|
|
590 // restore eaten '/'
|
|
|
591 outchr('/');
|
|
|
592 // process the character we just fetched
|
|
|
593 goto again;
|
|
|
594 }
|
|
|
595 } // switch
|
|
|
596 } // processing loop
|
|
|
597 }
|
|
|
598
|
|
|
599 int process_file(const char *f)
|
|
|
600 {
|
|
|
601 struct file_stack_e *nf;
|
|
|
602 FILE *fp;
|
|
|
603
|
|
|
604 fprintf(stderr, "Processing %s\n", f);
|
|
|
605
|
|
|
606 if (strcmp(f, "-") == 0)
|
|
|
607 fp = stdin;
|
|
|
608 else
|
|
|
609 fp = fopen(f, "rb");
|
|
|
610 if (fp == NULL)
|
|
|
611 {
|
|
|
612 do_warning("Cannot open %s: %s", f, strerror(errno));
|
|
|
613 return -1;
|
|
|
614 }
|
|
|
615
|
|
|
616 /* push the file onto the file stack */
|
|
|
617 nf = lw_alloc(sizeof(struct file_stack_e));
|
|
|
618 nf -> fn = f;
|
|
|
619 nf -> fp = fp;
|
|
|
620 nf -> next = file_stack;
|
|
|
621 nf -> line = 1;
|
|
|
622 nf -> col = 0;
|
|
|
623 nf -> qseen = 0;
|
|
|
624 nf -> ra = CPP_NOUNG;
|
|
|
625 nf -> unget = CPP_NOUNG;
|
|
|
626 file_stack = nf;
|
|
|
627
|
|
|
628 /* go preprocess the file */
|
|
|
629 preprocess_file(nf);
|
|
|
630
|
|
|
631 if (nf -> fp != stdin)
|
|
|
632 fclose(nf -> fp);
|
|
|
633 file_stack = nf -> next;
|
|
|
634 lw_free(nf);
|
|
|
635 return 0;
|
|
|
636 }
|
