libbb/yescrypt: use common ascii64 encoding routine

function                                             old     new   delta
num2str64_lsb_first                                   33      46     +13
yescrypt_r                                          1235    1133    -102
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/1 up/down: 13/-102)           Total: -89 bytes

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

2 files changed, 36 insertions, 66 deletions

diff --git a/libbb/yescrypt/alg-yescrypt-common.c b/libbb/yescrypt/alg-yescrypt-common.c
index 435eaecca..5bdf1893e 100644
--- a/libbb/yescrypt/alg-yescrypt-common.c
+++ b/libbb/yescrypt/alg-yescrypt-common.c
@@ -19,8 +19,8 @@
  */
 
 /* Not inlining:
- * decode64 fuinctions are only used to read
- * yescrypt_params_t field, and convert salt ti binary -
+ * de/encode64 functions are only used to read
+ * yescrypt_params_t field, and convert salt to binary -
  * both of these are negligible compared to main hashing operation
  */
 static NOINLINE const uint8_t *decode64_uint32(
@@ -63,56 +63,6 @@ fail:
         return NULL;
 }
 
-static uint8_t *encode64_uint32_fixed(
-                uint8_t *dst, size_t dstlen,
-                uint32_t src, uint32_t srcbits)
-{
-        uint32_t bits;
-
-        for (bits = 0; bits < srcbits; bits += 6) {
-                if (dstlen < 2)
-                        return NULL;
-                *dst++ = i2a64(src);
-                dstlen--;
-                src >>= 6;
-        }
-
-        if (src || dstlen < 1)
-                return NULL;
-
-        *dst = 0; /* NUL terminate just in case */
-
-        return dst;
-}
-
-static uint8_t *encode64(
-                uint8_t *dst, size_t dstlen,
-                const uint8_t *src, size_t srclen)
-{
-        size_t i;
-
-        for (i = 0; i < srclen; ) {
-                uint8_t *dnext;
-                uint32_t value = 0, bits = 0;
-                do {
-                        value |= (uint32_t)src[i++] << bits;
-                        bits += 8;
-                } while (bits < 24 && i < srclen);
-                dnext = encode64_uint32_fixed(dst, dstlen, value, bits);
-                if (!dnext)
-                        return NULL;
-                dstlen -= dnext - dst;
-                dst = dnext;
-        }
-
-        if (dstlen < 1)
-                return NULL;
-
-        *dst = 0; /* NUL terminate just in case */
-
-        return dst;
-}
-
 static const uint8_t *decode64(
                 uint8_t *dst, size_t *dstlen,
                 const uint8_t *src, size_t srclen)
@@ -156,21 +106,43 @@ static const uint8_t *decode64(
                 *dstlen = dstpos;
                 return src;
         }
-
 fail:
         *dstlen = 0;
         return NULL;
 }
 
-uint8_t *yescrypt_r(
+static char *encode64(
+                char *dst, size_t dstlen,
+                const uint8_t *src, size_t srclen)
+{
+        while (srclen) {
+                uint32_t value = 0, b = 0;
+                do {
+                        value |= (uint32_t)(*src++ << b);
+                        b += 8;
+                        srclen--;
+                } while (srclen && b < 24);
+
+                b >>= 3; /* number of bits to number of bytes */
+                b++; /* 1, 2 or 3 bytes will become 2, 3 or 4 ascii64 chars */
+                dstlen -= b;
+                if ((ssize_t)dstlen <= 0)
+                        return NULL;
+                dst = num2str64_lsb_first(dst, value, b);
+        }
+        *dst = '\0';
+        return dst;
+}
+
+char *yescrypt_r(
                 const uint8_t *passwd, size_t passwdlen,
                 const uint8_t *setting,
-                uint8_t *buf, size_t buflen)
+                char *buf, size_t buflen)
 {
         yescrypt_ctx_t yctx[1];
         unsigned char hashbin32[32];
+        char *dst;
         const uint8_t *src, *saltstr, *saltend;
-        uint8_t *dst;
         size_t need, prefixlen, saltstrlen;
         uint32_t flavor, N_log2;
 
@@ -241,11 +213,11 @@ uint8_t *yescrypt_r(
                                 goto fail;
                         yctx->param.NROM = (uint64_t)1 << NROM_log2;
                 }
+                if (!src)
+                        goto fail;
+                if (*src != '$')
+                        goto fail;
         }
-        if (!src)
-                goto fail;
-        if (*src != '$')
-                goto fail;
 
         saltstr = src + 1;
         src = (uint8_t *)strchrnul((char *)saltstr, '$');
@@ -268,16 +240,14 @@ uint8_t *yescrypt_r(
         dst = mempcpy(buf, setting, prefixlen);
         *dst++ = '$';
         dst = encode64(dst, buflen - (dst - buf), hashbin32, sizeof(hashbin32));
-        if (!dst || dst >= buf + buflen)
+        if (!dst)
                 goto fail;
-
-        *dst = 0; /* NUL termination */
  ret:
         free_region(yctx->local);
         explicit_bzero(yctx, sizeof(yctx));
         explicit_bzero(hashbin32, sizeof(hashbin32));
         return buf;
-fail:
+ fail:
         buf = NULL;
         goto ret;
 }
diff --git a/libbb/yescrypt/alg-yescrypt.h b/libbb/yescrypt/alg-yescrypt.h
index 5b442c2c9..996af333f 100644
--- a/libbb/yescrypt/alg-yescrypt.h
+++ b/libbb/yescrypt/alg-yescrypt.h
@@ -151,8 +151,8 @@ typedef struct {
  *
  * MT-safe as long as local and buf are local to the thread.
  */
-extern uint8_t *yescrypt_r(
+extern char *yescrypt_r(
             const uint8_t *passwd, size_t passwdlen,
             const uint8_t *setting,
-            uint8_t *buf, size_t buflen
+            char *buf, size_t buflen
 );