[英]Why this base64 function stop working when increasing max length?
I am using this class to encode/decode text to base64. 我正在使用此类将文本编码/解码为base64。 It works fine with MAX_LEN up to 512 but if I increase it to 1024 the decode function returns and empty var.
MAX_LEN最高可达512,它可以正常工作,但是如果我将其提高到1024,则解码函数将返回并且为空。
This is the function: 这是功能:
char* Base64::decode(char *src)
{
unsigned six, dix;
unsigned int d_len = MAX_LEN;
memset(dst,'\0', MAX_LEN);
unsigned s_len = strlen(src);
dix = 0;
for (six = 0; six < s_len; six += 4)
{
unsigned long sr;
unsigned ix;
sr = 0;
for (ix = 0; ix < 4; ++ix)
{
int sextet;
if (six+ix >= s_len)
return NULL;
if ((sextet = tlu(*(src+six+ix))) < 0)
break;
sr <<= 6;
sr |= (sextet & 0x3f);
}
switch (ix)
{
case 0: // end of data, no padding
return 0;
case 1: // can't happen
return NULL;
case 2: // 1 result byte
sr >>= 4;
if (dix > d_len) return NULL;
*(dst+dix) = (sr & 0xff);
++dix;
break;
case 3: // 2 result bytes
sr >>= 2;
if (dix+1 > d_len) return NULL;
*(dst+dix+1) = (sr & 0xff);
sr >>= 8;
*(dst+dix) = (sr & 0xff);
dix += 2;
break;
case 4: // 3 result bytes
if (dix+2 > d_len) return NULL;
*(dst+dix+2) = (sr & 0xff);
sr >>= 8;
*(dst+dix+1) = (sr & 0xff);
sr >>= 8;
*(dst+dix) = (sr & 0xff);
dix += 3;
break;
}
}
return dst;
}
Why could be causing this? 为什么会造成这种情况?
Odds are dst
is not sized correctly to hold all 1024 bytes. dst
的大小可能不正确,无法容纳所有1024个字节。 Without seeing dst
's declaration there is no way to be sure. 没有看到
dst
的声明,就无法确定。
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