41 lines
668 B
C
41 lines
668 B
C
#include <stdio.h>
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#include <string.h>
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inline int ishex(int x)
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{
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return (x >= '0' && x <= '9') ||
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(x >= 'a' && x <= 'f') ||
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(x >= 'A' && x <= 'F');
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}
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int decode(const char *s, char *dec)
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{
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char *o;
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const char *end = s + strlen(s);
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int c;
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for (o = dec; s <= end; o++) {
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c = *s++;
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if (c == '+') c = ' ';
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else if (c == '%' && ( !ishex(*s++) ||
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!ishex(*s++) ||
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!sscanf(s - 2, "%2x", &c)))
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return -1;
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if (dec) *o = c;
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}
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return o - dec;
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}
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int main()
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{
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const char *url = "http%3A%2F%2ffoo+bar%2fabcd";
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char out[strlen(url) + 1];
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printf("length: %d\n", decode(url, 0));
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puts(decode(url, out) < 0 ? "bad string" : out);
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return 0;
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}
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