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authorDenys Vlasenko2020-11-28 12:33:50 +0100
committerDenys Vlasenko2020-11-28 12:33:50 +0100
commitf140b49f5f631b09acf7811933d843fe17f06343 (patch)
tree97d5e77ed73a3864bd8ea4ca7b9ad0af8130e89a
parent7467e905e558228aab992f85406382518f2e1666 (diff)
downloadbusybox-f140b49f5f631b09acf7811933d843fe17f06343.zip
busybox-f140b49f5f631b09acf7811933d843fe17f06343.tar.gz
base32/64: code shrink
function old new delta decode_base64 178 173 -5 decode_base32 217 186 -31 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-36) Total: -36 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--libbb/uuencode.c66
1 files changed, 37 insertions, 29 deletions
diff --git a/libbb/uuencode.c b/libbb/uuencode.c
index 0e6fc8a..6205af2 100644
--- a/libbb/uuencode.c
+++ b/libbb/uuencode.c
@@ -92,8 +92,8 @@ const char* FAST_FUNC decode_base64(char **pp_dst, const char *src)
{
char *dst = *pp_dst;
unsigned ch = 0;
+ unsigned t;
int i = 0;
- int t;
while ((t = (unsigned char)*src) != '\0') {
src++;
@@ -117,11 +117,11 @@ const char* FAST_FUNC decode_base64(char **pp_dst, const char *src)
continue;
ch = (ch << 6) | t;
- if (++i == 4) {
+ i = (i + 1) & 3;
+ if (i == 0) {
*dst++ = (char) (ch >> 16);
*dst++ = (char) (ch >> 8);
*dst++ = (char) ch;
- i = 0;
if (ch & 0x1000000) { /* was last input char '='? */
dst--;
if (ch & (0x1000000 << 6)) /* was it "=="? */
@@ -140,9 +140,9 @@ const char* FAST_FUNC decode_base64(char **pp_dst, const char *src)
const char* FAST_FUNC decode_base32(char **pp_dst, const char *src)
{
char *dst = *pp_dst;
- uint64_t ch = 0;
+ int64_t ch = 0;
+ unsigned t;
int i = 0;
- int t;
while ((t = (unsigned char)*src) != '\0') {
src++;
@@ -150,44 +150,52 @@ const char* FAST_FUNC decode_base32(char **pp_dst, const char *src)
/* "if" forest is faster than strchr(bb_uuenc_tbl_base32, t) */
if (t >= '2' && t <= '7')
t = t - '2' + 26;
- else if ((t|0x20) >= 'a' && (t|0x20) <= 'z')
- t = (t|0x20) - 'a';
else if (t == '=' && i > 1)
t = 0;
- else
+ else {
+ t = (t | 0x20) - 'a';
+ if (t > 25)
//TODO: add BASE64_FLAG_foo to die on bad char?
- continue;
+ continue;
+ }
- ch = (ch << 5) | (unsigned)t; /* cast prevents pointless sign-extension of t */
- if (++i == 8) {
- /* 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==
- * ====
- * should correctly stitch together the tail.
- */
- if (t == 0) {
- const char *s = src;
- while (*--s == '=')
- t--;
- }
+ 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 = 0;
- if (t < 0) /* was last input char '='? */
- break;
}
}
- if (t < 0) /* was last input char '='? */
- /* -t is the count of =, must be 1, 3, 4 or 6 */
- dst -= (-t + 1) * 2 / 3; /* discard last 1, 2, 3 or 4 bytes */
*pp_dst = dst;
/* i is zero here if full 8-char block was decoded */
return src - i;
+ 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_dst = dst;
+ return src;
}
#endif