LXR busybox/libbb/uuencode.c

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * Copyright 2003, Glenn McGrath
   4 * Copyright 2006, Rob Landley <rob@landley.net>
   5 * Copyright 2010, Denys Vlasenko
   6 *
   7 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8 */
   9#include "libbb.h"
  10
  11/* Conversion tables */
  12#if ENABLE_BASE32
  13const char bb_uuenc_tbl_base32[] ALIGN1 = {
  14        'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
  15        'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
  16        'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
  17        'Y', 'Z', '2', '3', '4', '5', '6', '7',
  18        /* unused: '=', */
  19};
  20#endif
  21/* for base 64 */
  22const char bb_uuenc_tbl_base64[] ALIGN1 = {
  23        'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
  24        'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
  25        'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
  26        'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
  27        'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
  28        'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
  29        'w', 'x', 'y', 'z', '0', '1', '2', '3',
  30        '4', '5', '6', '7', '8', '9', '+', '/',
  31        '=' /* termination character */
  32};
  33const char bb_uuenc_tbl_std[] ALIGN1 = {
  34        '`', '!', '"', '#', '$', '%', '&', '\'',
  35        '(', ')', '*', '+', ',', '-', '.', '/',
  36        '0', '1', '2', '3', '4', '5', '6', '7',
  37        '8', '9', ':', ';', '<', '=', '>', '?',
  38        '@', 'A', 'B', 'C', 'D', 'E', 'F', 'G',
  39        'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
  40        'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W',
  41        'X', 'Y', 'Z', '[', '\\',']', '^', '_',
  42        '`' /* termination character */
  43};
  44
  45/*
  46 * Encode bytes at S of length LENGTH to uuencode or base64 format and place it
  47 * to STORE.  STORE will be 0-terminated, and must point to a writable
  48 * buffer of at least 1+BASE64_LENGTH(length) bytes.
  49 * where BASE64_LENGTH(len) = (4 * ((LENGTH + 2) / 3))
  50 */
  51void FAST_FUNC bb_uuencode(char *p, const void *src, int length, const char *tbl)
  52{
  53        const unsigned char *s = src;
  54
  55        /* Transform the 3x8 bits to 4x6 bits */
  56        while (length > 0) {
  57                unsigned s1, s2;
  58
  59                /* Are s[1], s[2] valid or should be assumed 0? */
  60                s1 = s2 = 0;
  61                length -= 3; /* can be >=0, -1, -2 */
  62                if (length >= -1) {
  63                        s1 = s[1];
  64                        if (length >= 0)
  65                                s2 = s[2];
  66                }
  67                *p++ = tbl[s[0] >> 2];
  68                *p++ = tbl[((s[0] & 3) << 4) + (s1 >> 4)];
  69                *p++ = tbl[((s1 & 0xf) << 2) + (s2 >> 6)];
  70                *p++ = tbl[s2 & 0x3f];
  71                s += 3;
  72        }
  73        /* Zero-terminate */
  74        *p = '\0';
  75        /* If length is -2 or -1, pad last char or two */
  76        while (length) {
  77                *--p = tbl[64];
  78                length++;
  79        }
  80}
  81
  82/*
  83 * Decode base64 encoded string.
  84 *
  85 * Returns: pointer past the last written output byte,
  86 * the result is not NUL-terminated.
  87 * (*pp_src) is advanced past the last read byte.
  88 * If points to '\0', then the source was fully decoded.
  89 */
  90char* FAST_FUNC decode_base64(char *dst, const char **pp_src)
  91{
  92        const char *src = pp_src ? *pp_src : dst; /* for httpd.c, support NULL 2nd param */
  93        unsigned ch = 0;
  94        unsigned t;
  95        int i = 0;
  96
  97        while ((t = (unsigned char)*src) != '\0') {
  98                src++;
  99
 100                /* "if" forest is faster than strchr(bb_uuenc_tbl_base64, t) */
 101                if (t >= '0' && t <= '9')
 102                        t = t - '0' + 52;
 103                else if (t >= 'A' && t <= 'Z')
 104                        t = t - 'A';
 105                else if (t >= 'a' && t <= 'z')
 106                        t = t - 'a' + 26;
 107                else if (t == '+')
 108                        t = 62;
 109                else if (t == '/')
 110                        t = 63;
 111                else if (t == '=' && (i == 3 || (i == 2 && *src == '=')))
 112                        /* the above disallows "==AA", "A===", "AA=A" etc */
 113                        t = 0x1000000;
 114                else
 115//TODO: add BASE64_FLAG_foo to die on bad char?
 116                        continue;
 117
 118                ch = (ch << 6) | t;
 119                i = (i + 1) & 3;
 120                if (i == 0) {
 121                        *dst++ = (char) (ch >> 16);
 122                        *dst++ = (char) (ch >> 8);
 123                        *dst++ = (char) ch;
 124                        if (ch & 0x1000000) { /* was last input char '='? */
 125                                dst--;
 126                                if (ch & (0x1000000 << 6)) /* was it "=="? */
 127                                        dst--;
 128                                break;
 129                        }
 130                        ch = 0;
 131                }
 132        }
 133        /* i is zero here if full 4-char block was decoded */
 134        if (pp_src)
 135                *pp_src = src - i; /* -i signals truncation: e.g. "MQ" and "MQ=" (correct encoding is "MQ==" -> "1") */
 136        return dst;
 137}
 138
 139#if ENABLE_BASE32
 140char* FAST_FUNC decode_base32(char *dst, const char **pp_src)
 141{
 142        const char *src = *pp_src;
 143        uint64_t ch = 0;
 144        unsigned t;
 145        int i = 0;
 146
 147        while ((t = (unsigned char)*src) != '\0') {
 148                src++;
 149
 150                /* "if" forest is faster than strchr(bb_uuenc_tbl_base32, t) */
 151                if (t >= '2' && t <= '7')
 152                        t = t - '2' + 26;
 153                else if (t == '=' && i > 1)
 154                        t = 0;
 155                else {
 156                        t = (t | 0x20) - 'a';
 157                        if (t > 25)
 158//TODO: add BASE64_FLAG_foo to die on bad char?
 159                                continue;
 160                }
 161
 162                ch = (ch << 5) | t;
 163                i = (i + 1) & 7;
 164                if (i == 0) {
 165                        *dst++ = (char) (ch >> 32);
 166                        if (src[-1] == '=') /* was last input char '='? */
 167                                goto tail;
 168                        *dst++ = (char) (ch >> 24);
 169                        *dst++ = (char) (ch >> 16);
 170                        *dst++ = (char) (ch >> 8);
 171                        *dst++ = (char) ch;
 172                }
 173        }
 174        /* i is zero here if full 8-char block was decoded */
 175        *pp_src = src - i;
 176        return dst;
 177 tail:
 178        {
 179                const char *s = src;
 180                while (*--s == '=')
 181                        i++;
 182                /* Why duplicate the below code? Testcase:
 183                 * echo ' 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18' | base32 | base32 -d
 184                 * IOW, decoding of
 185                 * EAYSAMRAGMQDIIBVEA3CANZAHAQDSIBRGAQDCMJAGEZCAMJTEAYTIIBRGUQDCNRAGE3SAMJYBI==
 186                 * ====
 187                 * must correctly stitch together the tail, must not overwrite
 188                 * the tail before it is analyzed! (we can be decoding in-place)
 189                 * Else testcase fails, prints trailing extra NUL bytes.
 190                 */
 191                *dst++ = (char) (ch >> 24);
 192                *dst++ = (char) (ch >> 16);
 193                *dst++ = (char) (ch >> 8);
 194                *dst++ = (char) ch;
 195                dst -= (i+1) * 2 / 3; /* discard last 1, 2, 3 or 4 bytes */
 196        }
 197        *pp_src = src;
 198        return dst;
 199}
 200#endif
 201
 202/*
 203 * Decode base64 encoded stream.
 204 * Can stop on EOF, specified char, or on uuencode-style "====" line:
 205 * flags argument controls it.
 206 */
 207void FAST_FUNC read_base64(FILE *src_stream, FILE *dst_stream, int flags)
 208{
 209/* Note that EOF _can_ be passed as exit_char too */
 210#define exit_char    ((int)(signed char)flags)
 211#define uu_style_end (flags & BASE64_FLAG_UU_STOP)
 212#define base32       (flags & BASE64_32)
 213
 214        /* uuencoded files have 61 byte lines.
 215         * base32/64 have 76 byte lines by default.
 216         * Use 80 byte buffer to process one line at a time.
 217         */
 218        enum { BUFFER_SIZE = 80 };
 219        /* decoded data is shorter than input, can use single buffer for both */
 220        char buf[BUFFER_SIZE + 2];
 221        int term_seen = 0;
 222        int in_count = 0;
 223
 224        while (1) {
 225                char *out_tail;
 226                const char *in_tail;
 227
 228                while (in_count < BUFFER_SIZE) {
 229                        int ch = fgetc(src_stream);
 230                        if (ch == exit_char) {
 231                                if (in_count == 0)
 232                                        return;
 233                                term_seen = 1;
 234                                break;
 235                        }
 236                        if (ch == EOF) {
 237                                term_seen = 1;
 238                                break;
 239                        }
 240                        /* Prevent "====" line to be split: stop if we see '\n'.
 241                         * We can also skip other whitespace and skirt the problem
 242                         * of files with NULs by stopping on any control char or space:
 243                         */
 244                        if (ch <= ' ')
 245                                break;
 246                        buf[in_count++] = ch;
 247                }
 248                buf[in_count] = '\0';
 249
 250                /* Did we encounter "====" line? */
 251                if (uu_style_end && strcmp(buf, "====") == 0)
 252                        return;
 253
 254                in_tail = buf;
 255#if ENABLE_BASE32
 256                if (base32)
 257                        out_tail = decode_base32(buf, &in_tail);
 258                else
 259#endif
 260                        out_tail = decode_base64(buf, &in_tail);
 261
 262                fwrite(buf, (out_tail - buf), 1, dst_stream);
 263
 264                if (term_seen) {
 265                        /* Did we consume ALL characters? */
 266                        if (*in_tail == '\0')
 267                                return;
 268                        /* No */
 269                        bb_simple_error_msg_and_die("truncated input");
 270                }
 271
 272                /* It was partial decode */
 273                in_count = strlen(in_tail);
 274                memmove(buf, in_tail, in_count);
 275        }
 276}
 277