152 lines
3.1 KiB
C
152 lines
3.1 KiB
C
/* queryparam() - allow program parameters to be queried
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* Author: Kees J. Bot
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* 21 Apr 1994
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*/
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#define nil 0
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#include <stddef.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/types.h>
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#include <minix3/queryparam.h>
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#if EXAMPLE
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struct stat st[2];
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struct export_param_list ex_st_list[]= {
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QP_VARIABLE(st),
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QP_ARRAY(st),
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QP_FIELD(st_dev, struct stat),
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QP_FIELD(st_ino, struct stat),
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...
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QP_END()
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};
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struct buf { block_t b_blocknr; ... } *buf;
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size_t nr_bufs;
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struct export_param_list ex_buf_list[]=
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QP_VECTOR(buf, buf, nr_bufs),
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QP_FIELD(b_blocknr),
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...
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QP_END()
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};
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struct export_params ex_st= { ex_st_list, 0 };
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struct export_params ex_buf= { ex_buf_list, 0 };
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#endif
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#define between(a, c, z) ((unsigned) ((c) - (a)) <= (unsigned) ((z) - (a)))
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static int isvar(int c)
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{
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return between('a', c, 'z') || between('A', c, 'Z')
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|| between('0', c, '9') || c == '_';
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}
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static struct export_params *params;
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void qp_export(struct export_params *ex_params)
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{
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/* Add a set of exported parameters. */
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if (ex_params->next == nil) {
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ex_params->next= params;
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params= ex_params;
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}
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}
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int queryparam(int qgetc(void), void **poffset, size_t *psize)
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{
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char *prefix;
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struct export_params *ep;
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struct export_param_list *epl;
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size_t offset= 0;
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size_t size= -1;
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size_t n;
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static size_t retval;
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int c, firstc;
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firstc= c= (*qgetc)();
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if (c == '&' || c == '$') c= (*qgetc)();
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if (!isvar(c)) goto fail;
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if ((ep= params) == nil) goto fail;
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epl= ep->list;
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while (c != 0 && c != ',') {
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prefix= "x";
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n= 0;
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for (;;) {
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while (epl->name == nil) {
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if ((ep= ep->next) == nil) goto fail;
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epl= ep->list;
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}
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if (strncmp(prefix, epl->name, n) == 0) {
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prefix= epl->name;
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while (prefix[n] != 0 && c == prefix[n]) {
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n++;
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c= (*qgetc)();
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}
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}
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if (prefix[n] == 0 && (!isvar(c) || prefix[0] == '[')) {
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/* Got a match. */
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break;
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}
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epl++;
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}
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if (prefix[0] == '[') {
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/* Array reference. */
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size_t idx= 0, cnt= 1, max= size / epl->size;
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while (between('0', c, '9')) {
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idx= idx * 10 + (c - '0');
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if (idx > max) goto fail;
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c= (*qgetc)();
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}
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if (c == ':') {
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cnt= 0;
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while (between('0', (c= (*qgetc)()), '9')) {
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cnt= cnt * 10 + (c - '0');
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}
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}
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if (c != ']') goto fail;
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if (idx + cnt > max) cnt= max - idx;
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offset+= idx * epl->size;
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size= cnt * epl->size;
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c= (*qgetc)();
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} else
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if (epl->size == -1) {
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/* Vector. */
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offset= (size_t) * (void **) epl->offset;
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size= (* (size_t *) epl[1].offset) * epl[1].size;
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} else {
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/* Variable or struct field. */
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offset+= (size_t) epl->offset;
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if ((size_t) epl->offset > size) goto fail;
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size-= (size_t) epl->offset;
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if (size < epl->size) goto fail;
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size= epl->size;
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}
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}
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if (firstc == '&' || firstc == '$') {
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retval= firstc == '&' ? offset : size;
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offset= (size_t) &retval;
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size= sizeof(retval);
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}
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if (c != 0 && c != ',') goto fail;
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*poffset= (void *) offset;
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*psize= size;
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return c != 0;
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fail:
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while (c != 0 && c != ',') c= (*qgetc)();
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*poffset= nil;
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*psize= 0;
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return c != 0;
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}
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/*
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* $PchId: queryparam.c,v 1.1 2005/06/28 14:30:56 philip Exp $
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*/
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