| 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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