diff options
| -rw-r--r-- | libbb/uuencode.c | 42 |
1 files changed, 23 insertions, 19 deletions
diff --git a/libbb/uuencode.c b/libbb/uuencode.c index 46ca796..f7b2484 100644 --- a/libbb/uuencode.c +++ b/libbb/uuencode.c @@ -10,7 +10,7 @@ #include "libbb.h" /* Conversion table. for base 64 */ -const char bb_uuenc_tbl_base64[65 + 2] ALIGN1 = { +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', @@ -20,7 +20,7 @@ const char bb_uuenc_tbl_base64[65 + 2] ALIGN1 = { 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/', '=' /* termination character */, - '\n', '\0' /* needed for uudecode.c */ + '\0' /* needed for uudecode.c only */ }; const char bb_uuenc_tbl_std[65] ALIGN1 = { @@ -77,7 +77,7 @@ void FAST_FUNC bb_uuencode(char *p, const void *src, int length, const char *tbl * * Returns: pointer to the undecoded part of source. * If points to '\0', then the source was fully decoded. - * (*dst): advanced past the last written byte. + * (*pp_dst): advanced past the last written byte. */ const char* FAST_FUNC decode_base64(char **pp_dst, const char *src) { @@ -85,10 +85,10 @@ const char* FAST_FUNC decode_base64(char **pp_dst, const char *src) const char *src_tail; while (1) { - unsigned char translated[4]; + unsigned char six_bit[4]; int count = 0; - /* Process one group of 4 chars */ + /* Fetch up to four 6-bit values */ src_tail = src; while (count < 4) { char *table_ptr; @@ -97,8 +97,8 @@ const char* FAST_FUNC decode_base64(char **pp_dst, const char *src) /* Get next _valid_ character. * bb_uuenc_tbl_base64[] contains this string: * 0 1 2 3 4 5 6 - * 012345678901234567890123456789012345678901234567890123456789012345 - * "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=\n" + * 01234567890123456789012345678901234567890123456789012345678901234 + * "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=" */ do { ch = *src; @@ -117,33 +117,37 @@ const char* FAST_FUNC decode_base64(char **pp_dst, const char *src) src++; 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' */ - continue; - } /* ch is 64 if char was '=', otherwise 0..63 */ - translated[count] = ch & 63; /* 64 -> 0 */ - if (ch == 64) { /* '=' */ + if (ch == 64) break; - } + six_bit[count] = ch; count++; } - /* Merge 6 bit chars to 8 bit. + /* Transform 6-bit values to 8-bit ones. * count can be < 4 when we decode the tail: - * "eQ==" -> "y", not "y NUL NUL" + * "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++ = translated[0] << 2 | translated[1] >> 4; + *dst++ = six_bit[0] << 2 | six_bit[1] >> 4; if (count > 2) - *dst++ = translated[1] << 4 | translated[2] >> 2; + *dst++ = six_bit[1] << 4 | six_bit[2] >> 2; if (count > 3) - *dst++ = translated[2] << 6 | translated[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; |