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Fix decode issue #2

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Fix decode issue #2

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16 changes: 14 additions & 2 deletions src/cdecode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,16 @@ void base64_init_decodestate(base64_decodestate* state_in)
state_in->plainchar = 0;
}

int is_next_codechar_anequal(const char* code_in_next, const int length_in_remaining)
{
// Do we have any characters remaining after this one?
if (length_in_remaining) {
if (*code_in_next == '=')
return (1); // We have an equal
}
return (0); // No more charcters available
}

int base64_decode_block(const char* code_in, const int length_in, char* plaintext_out, base64_decodestate* state_in)
{
const char* codechar = code_in;
Expand Down Expand Up @@ -56,7 +66,8 @@ int base64_decode_block(const char* code_in, const int length_in, char* plaintex
fragment = (char)base64_decode_value(*codechar++);
} while (fragment < 0);
*plainchar++ |= (fragment & 0x030) >> 4;
*plainchar = (fragment & 0x00f) << 4;
if (!is_next_codechar_anequal(codechar, length_in - (codechar - code_in)))
*plainchar = (fragment & 0x00f) << 4;
case step_c:
do {
if (codechar == code_in+length_in)
Expand All @@ -68,7 +79,8 @@ int base64_decode_block(const char* code_in, const int length_in, char* plaintex
fragment = (char)base64_decode_value(*codechar++);
} while (fragment < 0);
*plainchar++ |= (fragment & 0x03c) >> 2;
*plainchar = (fragment & 0x003) << 6;
if (!is_next_codechar_anequal(codechar, length_in - (codechar - code_in)))
*plainchar = (fragment & 0x003) << 6;
case step_d:
do {
if (codechar == code_in+length_in)
Expand Down