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decodeB.c
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decodeB.c
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#include "stralloc.h"
#include "strerr.h"
#include "uint32.h"
#include "messages.h"
#include "die.h"
#include "idx.h"
/* Characters and translation as per rfc2047. */
static const char char64table[128] = {
-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,62, -1,-1,-1,63,
52,53,54,55, 56,57,58,59, 60,61,-1,-1, -1,-1,-1,-1,
-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11,12,13,14,
15,16,17,18, 19,20,21,22, 23,24,25,-1, -1,-1,-1,-1,
-1,26,27,28, 29,30,31,32, 33,34,35,36, 37,38,39,40,
41,42,43,44, 45,46,47,48, 49,50,51,-1, -1,-1,-1,-1
};
#define char64enc(c) (((c) & 0x80) ? -1 : char64table[(c)])
void decodeB(const char *cpfrom,unsigned int n,stralloc *outdata)
/* does B decoding of the string pointed to by cpfrom up to the character */
/* before the one pointed to by cpnext, and appends the results to mimeline*/
{
uint32 hold32;
char holdch[4] = "???";
int i,j;
char c; /* needs to be signed */
const char *cp;
const char *cpnext;
cp = cpfrom;
cpnext = cp + n;
i = 0;
hold32 = 0L;
if (!stralloc_readyplus(outdata,n)) die_nomem();
for (;;) {
if (i == 4) {
for (j = 2; j >= 0; --j) {
holdch[j] = hold32 & 0xff;
hold32 = hold32 >> 8;
}
if (!stralloc_cats(outdata,holdch)) die_nomem();
if (cp >= cpnext)
break;
hold32 = 0L;
i = 0;
}
if (cp >= cpnext) { /* pad */
c = 0;
} else {
c = char64enc((unsigned)*cp);
++cp;
}
if (c < 0) /* ignore illegal characters */
continue;
else {
hold32 = (hold32 << 6) | (c & 0x7f);
++i;
}
}
}