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#include "scan.h"
size_t scan_varint(const char* in,size_t len, unsigned long long* n) {
size_t i;
unsigned long long l;
if (len==0) return 0;
for (l=0, i=0; i<len; ++i) {
if (i*7+7>sizeof(l)*8) /* value too large to fit in destination integer! */
return 0;
l+=(unsigned long long)(in[i]&0x7f) << (i*7);
if (!(in[i]&0x80)) {
if (in[i]==0) return 0; /* libowfat extension: reject non-minimal encoding */
*n=l;
return i+1;
}
}
return 0;
}
#ifdef __ELF__
size_t scan_pb_type0_int(const char* dest,size_t len,unsigned long long* l) __attribute__((alias("scan_varint")));
#else
size_t scan_pb_type0_int(const char* dest,size_t len,unsigned long long* l) {
return scan_varint(dest,len,l);
}
#endif
#ifdef UNITTEST
#include <assert.h>
int main() {
unsigned long long n;
assert(scan_varint("\x05",1,&n)==1 && n==5);
assert(scan_varint("\x80\x00",2,&n)==0); // non-minimal encoding
assert(scan_varint("\x80\x80",2,&n)==0); // truncated (last byte in sequence has high bit 0)
assert(scan_varint("\x80\x80\x80\x80\x80\x80\x80\x80\x80\x01",10,&n)==0); // value too large
return 0;
}
#endif
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