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annotate f-demime/base64.c @ 8:a92d0d59b669 default tip

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f-demime: indicate X-backslash-escapes encoding in output
author Mychaela Falconia <falcon@freecalypso.org>
date Sat, 06 May 2023 17:00:23 +0000
parents 7e0d08176f32
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
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0
7e0d08176f32 f-demime starting code
Mychaela Falconia <falcon@freecalypso.org>
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1 /*
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Mychaela Falconia <falcon@freecalypso.org>
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2 * This module implements base64 decoding.
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3 */
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4
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5 #include <ctype.h>
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6 #include <stdio.h>
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7 #include <stdlib.h>
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8 #include <string.h>
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9 #include <strings.h>
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10 #include "defs.h"
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11
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12 extern void (*dec_outf)();
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13
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14 static unsigned b64_accum, b64_eq_flag;
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15 static int b64_state, last_partial;
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16 int b64_err_flag, b64_nonempty;
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17
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18 void
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19 base64_dec_init()
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20 {
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21 b64_accum = 0;
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22 b64_eq_flag = 0;
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23 b64_state = 0;
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24 b64_err_flag = 0;
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25 b64_nonempty = 0;
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26 last_partial = 0;
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27 }
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28
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29 static void
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30 process_unit()
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31 {
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32 if (last_partial)
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33 b64_err_flag = 1;
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34 switch (b64_eq_flag) {
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35 case 0:
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36 dec_outf(b64_accum >> 16);
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37 dec_outf((b64_accum >> 8) & 0xFF);
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38 dec_outf(b64_accum & 0xFF);
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39 last_partial = 0;
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40 break;
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41 case 1:
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42 dec_outf(b64_accum >> 16);
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43 dec_outf((b64_accum >> 8) & 0xFF);
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44 last_partial = 1;
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45 break;
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46 case 3:
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47 dec_outf(b64_accum >> 16);
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48 last_partial = 1;
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49 break;
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50 default:
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51 b64_err_flag = 1;
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52 }
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53 b64_accum = 0;
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54 b64_eq_flag = 0;
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55 b64_state = 0;
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56 }
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57
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58 static void
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59 base64_input_char(ch)
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60 {
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61 int code;
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62
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63 b64_nonempty = 1;
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64 if (ch >= 'A' && ch <= 'Z')
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65 code = ch - 'A';
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66 else if (ch >= 'a' && ch <= 'z')
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67 code = ch - 'a' + 26;
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68 else if (ch >= '0' && ch <= '9')
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69 code = ch - '0' + 52;
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70 else switch (ch) {
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71 case '+':
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72 code = 62;
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73 break;
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74 case '/':
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75 code = 63;
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76 break;
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77 case '=':
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78 code = 64;
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79 break;
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80 default:
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81 b64_err_flag = 1;
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82 return;
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83 }
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84 b64_accum <<= 6;
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85 b64_accum |= (code & 63);
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86 b64_eq_flag <<= 1;
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87 b64_eq_flag |= (code >> 6);
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88 b64_state++;
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89 if (b64_state >= 4)
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90 process_unit();
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91 }
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92
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93 void
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94 base64_input_line(line)
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95 char *line;
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96 {
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97 char *cp;
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98 int c;
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99
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100 for (cp = line; *cp; ) {
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101 c = *cp++;
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102 if (!isspace(c))
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103 base64_input_char(c);
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104 }
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105 }
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106
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107 void
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108 base64_dec_finish()
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109 {
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110 if (b64_state)
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111 b64_err_flag = 1;
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112 }