1 | /* queryparam() - allow program parameters to be queried
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2 | * Author: Kees J. Bot
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3 | * 21 Apr 1994
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4 | */
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5 | #define nil 0
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6 | #include <stddef.h>
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7 | #include <stdlib.h>
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8 | #include <string.h>
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9 | #include <sys/types.h>
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10 | #include <minix3/queryparam.h>
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11 |
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12 | #if EXAMPLE
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13 | struct stat st[2];
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14 |
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15 | struct export_param_list ex_st_list[]= {
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16 | QP_VARIABLE(st),
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17 | QP_ARRAY(st),
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18 | QP_FIELD(st_dev, struct stat),
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19 | QP_FIELD(st_ino, struct stat),
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20 | ...
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21 | QP_END()
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22 | };
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23 |
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24 | struct buf { block_t b_blocknr; ... } *buf;
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25 | size_t nr_bufs;
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26 |
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27 | struct export_param_list ex_buf_list[]=
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28 | QP_VECTOR(buf, buf, nr_bufs),
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29 | QP_FIELD(b_blocknr),
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30 | ...
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31 | QP_END()
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32 | };
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33 |
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34 | struct export_params ex_st= { ex_st_list, 0 };
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35 | struct export_params ex_buf= { ex_buf_list, 0 };
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36 | #endif
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37 |
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38 | #define between(a, c, z) ((unsigned) ((c) - (a)) <= (unsigned) ((z) - (a)))
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39 |
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40 | static int isvar(int c)
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41 | {
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42 | return between('a', c, 'z') || between('A', c, 'Z')
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43 | || between('0', c, '9') || c == '_';
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44 | }
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45 |
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46 | static struct export_params *params;
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47 |
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48 | void qp_export(struct export_params *ex_params)
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49 | {
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50 | /* Add a set of exported parameters. */
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51 |
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52 | if (ex_params->next == nil) {
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53 | ex_params->next= params;
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54 | params= ex_params;
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55 | }
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56 | }
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57 |
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58 | int queryparam(int qgetc(void), void **poffset, size_t *psize)
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59 | {
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60 | char *prefix;
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61 | struct export_params *ep;
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62 | struct export_param_list *epl;
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63 | size_t offset= 0;
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64 | size_t size= -1;
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65 | size_t n;
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66 | static size_t retval;
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67 | int c, firstc;
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68 |
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69 | firstc= c= (*qgetc)();
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70 | if (c == '&' || c == '$') c= (*qgetc)();
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71 | if (!isvar(c)) goto fail;
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72 |
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73 | if ((ep= params) == nil) goto fail;
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74 | epl= ep->list;
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75 |
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76 | while (c != 0 && c != ',') {
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77 | prefix= "x";
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78 | n= 0;
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79 |
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80 | for (;;) {
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81 | while (epl->name == nil) {
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82 | if ((ep= ep->next) == nil) goto fail;
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83 | epl= ep->list;
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84 | }
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85 | if (strncmp(prefix, epl->name, n) == 0) {
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86 | prefix= epl->name;
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87 | while (prefix[n] != 0 && c == prefix[n]) {
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88 | n++;
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89 | c= (*qgetc)();
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90 | }
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91 | }
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92 | if (prefix[n] == 0 && (!isvar(c) || prefix[0] == '[')) {
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93 | /* Got a match. */
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94 | break;
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95 | }
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96 | epl++;
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97 | }
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98 |
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99 | if (prefix[0] == '[') {
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100 | /* Array reference. */
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101 | size_t idx= 0, cnt= 1, max= size / epl->size;
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102 |
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103 | while (between('0', c, '9')) {
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104 | idx= idx * 10 + (c - '0');
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105 | if (idx > max) goto fail;
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106 | c= (*qgetc)();
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107 | }
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108 | if (c == ':') {
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109 | cnt= 0;
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110 | while (between('0', (c= (*qgetc)()), '9')) {
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111 | cnt= cnt * 10 + (c - '0');
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112 | }
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113 | }
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114 | if (c != ']') goto fail;
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115 | if (idx + cnt > max) cnt= max - idx;
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116 | offset+= idx * epl->size;
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117 | size= cnt * epl->size;
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118 | c= (*qgetc)();
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119 | } else
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120 | if (epl->size == -1) {
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121 | /* Vector. */
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122 | offset= (size_t) * (void **) epl->offset;
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123 | size= (* (size_t *) epl[1].offset) * epl[1].size;
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124 | } else {
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125 | /* Variable or struct field. */
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126 | offset+= (size_t) epl->offset;
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127 | if ((size_t) epl->offset > size) goto fail;
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128 | size-= (size_t) epl->offset;
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129 | if (size < epl->size) goto fail;
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130 | size= epl->size;
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131 | }
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132 | }
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133 | if (firstc == '&' || firstc == '$') {
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134 | retval= firstc == '&' ? offset : size;
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135 | offset= (size_t) &retval;
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136 | size= sizeof(retval);
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137 | }
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138 | if (c != 0 && c != ',') goto fail;
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139 | *poffset= (void *) offset;
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140 | *psize= size;
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141 | return c != 0;
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142 | fail:
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143 | while (c != 0 && c != ',') c= (*qgetc)();
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144 | *poffset= nil;
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145 | *psize= 0;
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146 | return c != 0;
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147 | }
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148 |
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149 | /*
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150 | * $PchId: queryparam.c,v 1.1 2005/06/28 14:30:56 philip Exp $
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151 | */
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