Move default base32 alphabet to EncodeBase32 function

net/http/base32.c

@@ -26,6 +26,8 @@ Apache License, Version 2.0\\n\
 Copyright 2010 Google Inc.\"");
 asm(".include \"libc/disclaimer.inc\"");
 
+const char base32def[] = "0123456789abcdefghjkmnpqrstvwxyz";
+
 int tobits(int b) {
   int bits = 0; while (b && (b >>= 1)) bits++;
   return bits;
@@ -38,9 +40,13 @@ int tobits(int b) {
 char* EncodeBase32(const char *s, size_t sl,
                    const char *a, size_t al,
                    size_t *ol) {
-  unassert(2 <= al && al <= 256);
   size_t count = 0;
   char *r;
+  if (al == 0) {
+    a = base32def;
+    al = sizeof(base32def)/sizeof(a[0]);
+  }
+  unassert(2 <= al && al <= 128);
   int bl = tobits(al);
   int mask = (1 << bl) - 1;
   *ol = (sl * 8 + bl - 1) / bl; // calculate exact output length

tool/net/lfuncs.c

@@ -609,9 +609,10 @@ int LuaEncodeBase32(lua_State *L) {
   char *p;
   size_t sl, al; // source/output and alphabet lengths
   const char *s = luaL_checklstring(L, 1, &sl);
-  const char *a = luaL_optlstring(L, 2, "0123456789abcdefghjkmnpqrstvwxyz", &al);
-  if (al & (al - 1) || al > 256 || al < 2)
-    return luaL_error(L, "alphabet length is not a power of 2 in range 2..256");
+  // use an empty string, as EncodeBase32 provides a default value
+  const char *a = luaL_optlstring(L, 2, "", &al);
+  if (al & (al - 1) || al > 128 || al == 1)
+    return luaL_error(L, "alphabet length is not a power of 2 in range 2..128");
   if (!(p = EncodeBase32(s, sl, a, al, &sl)))
     return luaL_error(L, "out of memory");
   lua_pushlstring(L, p, sl);