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/* vi: set sw=4 ts=4: */
/*
* Copyright 2003, Glenn McGrath
* Copyright 2006, Rob Landley <rob@landley.net>
* Copyright 2010, Denys Vlasenko
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
#include "libbb.h"
/* Conversion table. for base 64 */
const char bb_uuenc_tbl_base64[65 + 1] ALIGN1 = {
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
'w', 'x', 'y', 'z', '0', '1', '2', '3',
'4', '5', '6', '7', '8', '9', '+', '/',
'=' /* termination character */,
'\0' /* needed for uudecode.c only */
};
const char bb_uuenc_tbl_std[65] ALIGN1 = {
'`', '!', '"', '#', '$', '%', '&', '\'',
'(', ')', '*', '+', ',', '-', '.', '/',
'0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', ':', ';', '<', '=', '>', '?',
'@', 'A', 'B', 'C', 'D', 'E', 'F', 'G',
'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W',
'X', 'Y', 'Z', '[', '\\', ']', '^', '_',
'`' /* termination character */
};
/*
* Encode bytes at S of length LENGTH to uuencode or base64 format and place it
* to STORE. STORE will be 0-terminated, and must point to a writable
* buffer of at least 1+BASE64_LENGTH(length) bytes.
* where BASE64_LENGTH(len) = (4 * ((LENGTH + 2) / 3))
*/
void FAST_FUNC bb_uuencode(char *p, const void *src, int length, const char *tbl)
{
const unsigned char *s = src;
/* Transform the 3x8 bits to 4x6 bits */
while (length > 0) {
unsigned s1, s2;
/* Are s[1], s[2] valid or should be assumed 0? */
s1 = s2 = 0;
length -= 3; /* can be >=0, -1, -2 */
if (length >= -1) {
s1 = s[1];
if (length >= 0)
s2 = s[2];
}
*p++ = tbl[s[0] >> 2];
*p++ = tbl[((s[0] & 3) << 4) + (s1 >> 4)];
*p++ = tbl[((s1 & 0xf) << 2) + (s2 >> 6)];
*p++ = tbl[s2 & 0x3f];
s += 3;
}
/* Zero-terminate */
*p = '\0';
/* If length is -2 or -1, pad last char or two */
while (length) {
*--p = tbl[64];
length++;
}
}
/*
* Decode base64 encoded string. Stops on '\0'.
*
* Returns: pointer to the undecoded part of source.
* If points to '\0', then the source was fully decoded.
* (*pp_dst): advanced past the last written byte.
*/
const char* FAST_FUNC decode_base64(char **pp_dst, const char *src)
{
char *dst = *pp_dst;
const char *src_tail;
while (1) {
unsigned char six_bit[4];
int count = 0;
/* Fetch up to four 6-bit values */
src_tail = src;
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
* 01234567890123456789012345678901234567890123456789012345678901234
* "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="
*/
do {
ch = *src;
if (ch == '\0') {
if (count == 0) {
/* Example:
* If we decode "QUJD <NUL>", we want
* to return ptr to NUL, not to ' ',
* because we did fully decode
* the string (to "ABC").
*/
src_tail = src;
}
goto ret;
}
src++;
table_ptr = strchr(bb_uuenc_tbl_base64, ch);
//TODO: add BASE64_FLAG_foo to die on bad char?
} while (!table_ptr);
/* Convert encoded character to decimal */
ch = table_ptr - bb_uuenc_tbl_base64;
/* ch is 64 if char was '=', otherwise 0..63 */
if (ch == 64)
break;
six_bit[count] = ch;
count++;
}
/* Transform 6-bit values to 8-bit ones.
* count can be < 4 when we decode the tail:
* "eQ==" -> "y", not "y NUL NUL".
* Note that (count > 1) is always true,
* "x===" encoding is not valid:
* even a single zero byte encodes as "AA==".
* However, with current logic we come here with count == 1
* when we decode "==" tail.
*/
if (count > 1)
*dst++ = six_bit[0] << 2 | six_bit[1] >> 4;
if (count > 2)
*dst++ = six_bit[1] << 4 | six_bit[2] >> 2;
if (count > 3)
*dst++ = six_bit[2] << 6 | six_bit[3];
/* Note that if we decode "AA==" and ate first '=',
* we just decoded one char (count == 2) and now we'll
* do the loop once more to decode second '='.
*/
} /* while (1) */
ret:
*pp_dst = dst;
return src_tail;
}
/*
* Decode base64 encoded stream.
* Can stop on EOF, specified char, or on uuencode-style "====" line:
* flags argument controls it.
*/
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_UU_STOP)
/* uuencoded files have 61 byte lines. Use 64 byte buffer
* to process line at a time.
*/
enum { BUFFER_SIZE = 64 };
char in_buf[BUFFER_SIZE + 2];
char out_buf[BUFFER_SIZE / 4 * 3 + 2];
char *out_tail;
const char *in_tail;
int term_seen = 0;
int in_count = 0;
while (1) {
while (in_count < BUFFER_SIZE) {
int ch = fgetc(src_stream);
if (ch == exit_char) {
if (in_count == 0)
return;
term_seen = 1;
break;
}
if (ch == EOF) {
term_seen = 1;
break;
}
/* Prevent "====" line to be split: stop if we see '\n'.
* We can also skip other whitespace and skirt the problem
* of files with NULs by stopping on any control char or space:
*/
if (ch <= ' ')
break;
in_buf[in_count++] = ch;
}
in_buf[in_count] = '\0';
/* Did we encounter "====" line? */
if (uu_style_end && strcmp(in_buf, "====") == 0)
return;
out_tail = out_buf;
in_tail = decode_base64(&out_tail, in_buf);
fwrite(out_buf, (out_tail - out_buf), 1, dst_stream);
if (term_seen) {
/* Did we consume ALL characters? */
if (*in_tail == '\0')
return;
/* No */
bb_error_msg_and_die("truncated base64 input");
}
/* It was partial decode */
in_count = strlen(in_tail);
memmove(in_buf, in_tail, in_count);
}
}
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