busybox/libbb/uuencode.c

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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 tables */
#if ENABLE_BASE32
const char bb_uuenc_tbl_base32[] 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', '2', '3', '4', '5', '6', '7',
/* unused: '=', */
};
#endif
/* for base 64 */
const char bb_uuenc_tbl_base64[] 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 */
};
const char bb_uuenc_tbl_std[] 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.
*
* Returns: pointer past the last written output byte,
* the result is not NUL-terminated.
* (*pp_src) is advanced past the last read byte.
* If points to '\0', then the source was fully decoded.
*/
char* FAST_FUNC decode_base64(char *dst, const char **pp_src)
{
const char *src = pp_src ? *pp_src : dst; /* for httpd.c, support NULL 2nd param */
unsigned ch = 0;
unsigned t;
int i = 0;
while ((t = (unsigned char)*src) != '\0') {
src++;
/* "if" forest is faster than strchr(bb_uuenc_tbl_base64, t) */
if (t >= '0' && t <= '9')
t = t - '0' + 52;
else if (t >= 'A' && t <= 'Z')
t = t - 'A';
else if (t >= 'a' && t <= 'z')
t = t - 'a' + 26;
else if (t == '+')
t = 62;
else if (t == '/')
t = 63;
else if (t == '=' && (i == 3 || (i == 2 && *src == '=')))
/* the above disallows "==AA", "A===", "AA=A" etc */
t = 0x1000000;
else
//TODO: add BASE64_FLAG_foo to die on bad char?
continue;
ch = (ch << 6) | t;
i = (i + 1) & 3;
if (i == 0) {
*dst++ = (char) (ch >> 16);
*dst++ = (char) (ch >> 8);
*dst++ = (char) ch;
if (ch & 0x1000000) { /* was last input char '='? */
dst--;
if (ch & (0x1000000 << 6)) /* was it "=="? */
dst--;
break;
}
ch = 0;
}
}
/* i is zero here if full 4-char block was decoded */
if (pp_src)
*pp_src = src - i; /* -i signals truncation: e.g. "MQ" and "MQ=" (correct encoding is "MQ==" -> "1") */
return dst;
}
#if ENABLE_BASE32
char* FAST_FUNC decode_base32(char *dst, const char **pp_src)
{
const char *src = *pp_src;
uint64_t ch = 0;
unsigned t;
int i = 0;
while ((t = (unsigned char)*src) != '\0') {
src++;
/* "if" forest is faster than strchr(bb_uuenc_tbl_base32, t) */
if (t >= '2' && t <= '7')
t = t - '2' + 26;
else if (t == '=' && i > 1)
t = 0;
else {
t = (t | 0x20) - 'a';
if (t > 25)
//TODO: add BASE64_FLAG_foo to die on bad char?
continue;
}
ch = (ch << 5) | t;
i = (i + 1) & 7;
if (i == 0) {
*dst++ = (char) (ch >> 32);
if (src[-1] == '=') /* was last input char '='? */
goto tail;
*dst++ = (char) (ch >> 24);
*dst++ = (char) (ch >> 16);
*dst++ = (char) (ch >> 8);
*dst++ = (char) ch;
}
}
/* i is zero here if full 8-char block was decoded */
*pp_src = src - i;
return dst;
tail:
{
const char *s = src;
while (*--s == '=')
i++;
/* Why duplicate the below code? Testcase:
* echo ' 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18' | base32 | base32 -d
* IOW, decoding of
* EAYSAMRAGMQDIIBVEA3CANZAHAQDSIBRGAQDCMJAGEZCAMJTEAYTIIBRGUQDCNRAGE3SAMJYBI==
* ====
* must correctly stitch together the tail, must not overwrite
* the tail before it is analyzed! (we can be decoding in-place)
* Else testcase fails, prints trailing extra NUL bytes.
*/
*dst++ = (char) (ch >> 24);
*dst++ = (char) (ch >> 16);
*dst++ = (char) (ch >> 8);
*dst++ = (char) ch;
dst -= (i+1) * 2 / 3; /* discard last 1, 2, 3 or 4 bytes */
}
*pp_src = src;
return dst;
}
#endif
/*
* 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)
#define base32 (flags & BASE64_32)
/* uuencoded files have 61 byte lines.
* base32/64 have 76 byte lines by default.
* Use 80 byte buffer to process one line at a time.
*/
enum { BUFFER_SIZE = 80 };
/* decoded data is shorter than input, can use single buffer for both */
char buf[BUFFER_SIZE + 2];
int term_seen = 0;
int in_count = 0;
while (1) {
char *out_tail;
const char *in_tail;
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;
buf[in_count++] = ch;
}
buf[in_count] = '\0';
/* Did we encounter "====" line? */
if (uu_style_end && strcmp(buf, "====") == 0)
return;
in_tail = buf;
#if ENABLE_BASE32
if (base32)
out_tail = decode_base32(buf, &in_tail);
else
#endif
out_tail = decode_base64(buf, &in_tail);
fwrite(buf, (out_tail - buf), 1, dst_stream);
if (term_seen) {
/* Did we consume ALL characters? */
if (*in_tail == '\0')
return;
/* No */
bb_simple_error_msg_and_die("truncated input");
}
/* It was partial decode */
in_count = strlen(in_tail);
memmove(buf, in_tail, in_count);
}
}