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/* vi: set sw=4 ts=4: */
/*
* Utility routines.
*
* Copyright 2003, Glenn McGrath
* Copyright 2010, Denys Vlasenko
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
#include "libbb.h"
//kbuild:lib-y += base64.o
void FAST_FUNC read_base64(FILE *src_stream, FILE *dst_stream, int flags)
{
/* Note that EOF _can_ be passed as exit_char too */
#define exit_char ((int)(signed char)flags)
#define uu_style_end (flags & BASE64_FLAG_UUEND)
int term_count = 0;
while (1) {
unsigned char translated[4];
int count = 0;
/* Process one group of 4 chars */
while (count < 4) {
char *table_ptr;
int ch;
/* Get next _valid_ character.
* bb_uuenc_tbl_base64[] contains this string:
* 0 1 2 3 4 5 6
* 012345678901234567890123456789012345678901234567890123456789012345
* "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=\n"
*/
do {
ch = fgetc(src_stream);
if (ch == exit_char && count == 0)
return;
if (ch == EOF)
bb_error_msg_and_die("truncated base64 input");
table_ptr = strchr(bb_uuenc_tbl_base64, ch);
//TODO: add BASE64_FLAG_foo to die on bad char?
//Note that then we may need to still allow '\r' (for mail processing)
} while (!table_ptr);
/* Convert encoded character to decimal */
ch = table_ptr - bb_uuenc_tbl_base64;
if (ch == 65 /* '\n' */) {
/* Terminating "====" line? */
if (uu_style_end && term_count == 4)
return; /* yes */
continue;
}
/* ch is 64 if char was '=', otherwise 0..63 */
translated[count] = ch & 63; /* 64 -> 0 */
if (ch == 64) {
term_count++;
break;
}
term_count = 0;
count++;
}
/* Merge 6 bit chars to 8 bit.
* count can be < 4 when we decode the tail:
* "eQ==" -> "y", not "y NUL NUL"
*/
if (count > 1)
fputc(translated[0] << 2 | translated[1] >> 4, dst_stream);
if (count > 2)
fputc(translated[1] << 4 | translated[2] >> 2, dst_stream);
if (count > 3)
fputc(translated[2] << 6 | translated[3], dst_stream);
} /* while (1) */
}
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