libbb/yescrypt: no need to find salt-terminating "$" twice

function                                             old     new   delta
yescrypt_r                                          1048    1029     -19

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 10 insertions, 16 deletions

diff --git a/libbb/yescrypt/alg-yescrypt-common.c b/libbb/yescrypt/alg-yescrypt-common.c
index 99e8b1277..dfcf32145 100644
--- a/libbb/yescrypt/alg-yescrypt-common.c
+++ b/libbb/yescrypt/alg-yescrypt-common.c
@@ -66,7 +66,7 @@ fail:
 #if 1
 static const uint8_t *decode64(
                 uint8_t *dst, size_t *dstlen,
-                const uint8_t *src, size_t srclen)
+                const uint8_t *src)
 {
         size_t dstpos = 0;
 
@@ -74,11 +74,9 @@ static const uint8_t *decode64(
         for (;;) {
                 uint32_t c, value = 0;
                 int bits = 0;
-                while (srclen != 0) {
-                        srclen--;
+                while (*src && *src != '$') {
                         c = a2i64(*src);
                         if (c > 63) { /* bad ascii64 char, stop decoding at it */
-                                srclen = 0;
                                 break;
                         }
                         src++;
@@ -94,7 +92,7 @@ static const uint8_t *decode64(
  store:
                 dbg_dec64(" storing bits:%d v:%08x", bits, (int)SWAP_BE32(value)); //BE to see lsb first
                 while (dstpos < *dstlen) {
-                        if (srclen == 0 && value == 0 && bits < 8) {
+                        if (!(*src && *src != '$') && value == 0 && bits < 8) {
                                 /* Example: mkpasswd PWD '$y$j9T$123':
                                  * the "123" is bits:18 value:03,51,00
                                  * is considered to be 2 bytes, not 3!
@@ -118,7 +116,7 @@ static const uint8_t *decode64(
                 dbg_dec64(" ERR: bits:%d dst[] is too small", bits);
                 goto fail;
  next:
-                if (srclen == 0)
+                if (!*src || *src == '$')
                         break;
         }
  end:
@@ -214,8 +212,8 @@ char *yescrypt_r(
         yescrypt_ctx_t yctx[1];
         unsigned char hashbin32[32];
         char *dst;
-        const uint8_t *src, *saltstr, *saltend;
-        size_t need, prefixlen, saltstrlen;
+        const uint8_t *src, *saltend;
+        size_t need, prefixlen;
         uint32_t u32;
 
         memset(yctx, 0, sizeof(yctx));
@@ -280,17 +278,13 @@ char *yescrypt_r(
                         goto fail;
         }
 
-        saltstr = src + 1;
-        src = (uint8_t *)strchrnul((char *)saltstr, '$');
-        prefixlen = src - setting;  /* len("$y$<params>$<salt>") */
-        saltstrlen = src - saltstr; /* len("<salt>") */
-        /* src points to end of salt ('$' or NUL byte), won't be used past this point */
-
         yctx->saltlen = sizeof(yctx->salt);
-        saltend = decode64(yctx->salt, &yctx->saltlen, saltstr, saltstrlen);
-        if (saltend != saltstr + saltstrlen)
+        src++; /* now points to salt */
+        saltend = decode64(yctx->salt, &yctx->saltlen, src);
+        if (!saltend || (*saltend != '\0' && *saltend != '$'))
                 goto fail; /* salt[] is too small, or bad char during decode */
 
+        prefixlen = saltend - setting;
         need = prefixlen + 1 + YESCRYPT_HASH_LEN + 1;
         if (need > buflen || need < prefixlen)
                 goto fail;