Mirror of :pserver:cvs@cvs.fefe.de:/cvs libowfat https://www.fefe.de/libowfat/
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#include "textcode.h"
#include "haveinline.h"
static inline int dec(unsigned char x) {
if (x>='A' && x<='Z') return x-'A';
if (x>='a' && x<='z') return x-'a'+26;
if (x>='0' && x<='9') return x-'0'+26+26;
switch (x) {
case '+': return 62;
case '/': return 63;
default: return -1;
}
}
size_t scan_base64(const char *src,char *dest,size_t *destlen) {
unsigned short tmp=0,bits=0;
register const unsigned char* s=(const unsigned char*) src;
const char* orig=src;
size_t i,j=0;
for (i=0;;) {
int a=dec(*s);
if (a<0) {
int equal=(*s=='=');
while (*s=='=' && ((s-(const unsigned char*)src)&3)) ++s;
tmp &= ((1<<bits)-1);
if (!tmp || equal) { j=i; orig=(const char*)s; }
break;
}
tmp=(tmp<<6)|a; bits+=6;
++s;
if (bits>=8) {
bits-=8;
if (dest) dest[i]=(tmp>>bits);
++i;
if (!bits) { j=i; orig=(const char*)s; }
}
}
if (destlen) *destlen=j;
return orig-src;
}
#ifdef UNITTEST
#include <assert.h>
#include <string.h>
#include <stdio.h>
int main() {
char buf[100];
size_t i,l;
memset(buf,0,10); assert(scan_base64("Zm5vcmQ=",buf,&l)==8 && l==5 && !memcmp(buf,"fnord",6));
/* check that we don't insist on the padding */
memset(buf,0,10); assert(scan_base64("Zm5vcmQ",buf,&l)==7 && l==5 && !memcmp(buf,"fnord",6));
/* check the special non-isalnum chars :) */
memset(buf,0,10); assert(scan_base64("/+8=",buf,&l)==4 && l==2 && !memcmp(buf,"\xff\xef",3));
return 0;
}
#endif