Support unpack template "U"

src/pack.c

@@ -448,6 +448,80 @@ pack_utf8(mrb_state *mrb, mrb_value o, mrb_value str, mrb_int sidx, long count,
   return len;
 }
 
+static const unsigned long utf8_limits[] = {
+  0x0,        /* 1 */
+  0x80,       /* 2 */
+  0x800,      /* 3 */
+  0x10000,    /* 4 */
+  0x200000,   /* 5 */
+  0x4000000,  /* 6 */
+  0x80000000, /* 7 */
+};
+
+static unsigned long
+utf8_to_uv(mrb_state *mrb, const char *p, long *lenp)
+{
+  int c = *p++ & 0xff;
+  unsigned long uv = c;
+  long n;
+
+  if (!(uv & 0x80)) {
+    *lenp = 1;
+    return uv;
+  }
+  if (!(uv & 0x40)) {
+    *lenp = 1;
+    mrb_raise(mrb, E_ARGUMENT_ERROR, "malformed UTF-8 character");
+  }
+
+  if      (!(uv & 0x20)) { n = 2; uv &= 0x1f; }
+  else if (!(uv & 0x10)) { n = 3; uv &= 0x0f; }
+  else if (!(uv & 0x08)) { n = 4; uv &= 0x07; }
+  else if (!(uv & 0x04)) { n = 5; uv &= 0x03; }
+  else if (!(uv & 0x02)) { n = 6; uv &= 0x01; }
+  else {
+    *lenp = 1;
+    mrb_raise(mrb, E_ARGUMENT_ERROR, "malformed UTF-8 character");
+  }
+  if (n > *lenp) {
+    mrb_raisef(mrb, E_ARGUMENT_ERROR, "malformed UTF-8 character (expected %S bytes, given %S bytes)",
+    mrb_fixnum_value(n), mrb_fixnum_value(*lenp));
+  }
+  *lenp = n--;
+  if (n != 0) {
+    while (n--) {
+      c = *p++ & 0xff;
+      if ((c & 0xc0) != 0x80) {
+        *lenp -= n + 1;
+        mrb_raisef(mrb, E_ARGUMENT_ERROR, "malformed UTF-8 character");
+      }
+      else {
+        c &= 0x3f;
+        uv = uv << 6 | c;
+      }
+    }
+  }
+  n = *lenp - 1;
+  if (uv < utf8_limits[n]) {
+    mrb_raisef(mrb, E_ARGUMENT_ERROR, "redundant UTF-8 sequence");
+  }
+  return uv;
+}
+
+static int
+unpack_utf8(mrb_state *mrb, const unsigned char * src, int srclen, mrb_value ary, unsigned int flags)
+{
+  unsigned long uv;
+  long lenp = srclen;
+
+  if (srclen == 0) {
+    return 1;
+  }
+  uv = utf8_to_uv(mrb, (const char *)src, &lenp);
+  mrb_ary_push(mrb, ary, mrb_fixnum_value((mrb_int)uv));
+  return (int)lenp;
+}
+
 static int
 pack_a(mrb_state *mrb, mrb_value src, mrb_value dst, mrb_int didx, long count, unsigned int flags)
 {
@@ -482,7 +556,7 @@ pack_a(mrb_state *mrb, mrb_value src, mrb_value dst, mrb_int didx, long count, u
   while (padlen-- > 0) {
     *dptr++ = pad;
   }
- 
+
   return dptr - dptr0;
 }
 
@@ -541,7 +615,7 @@ pack_h(mrb_state *mrb, mrb_value src, mrb_value dst, mrb_int didx, long count, u
   } else if (slen > count) {
     slen = count;
   }
-    
+
   dst = str_len_ensure(mrb, dst, didx + count);
   dptr = RSTRING_PTR(dst) + didx;
 
@@ -1151,6 +1225,11 @@ mrb_pack_unpack(mrb_state *mrb, mrb_value str)
       case PACK_DIR_DOUBLE:
         srcidx += unpack_double(mrb, sptr, srclen - srcidx, result, flags);
         break;
+      case PACK_DIR_UTF8:
+        srcidx += unpack_utf8(mrb, sptr, srclen - srcidx, result, flags);
+        break;
+      default:
+        mrb_raise(mrb, E_RUNTIME_ERROR, "mruby-pack's bug");
       }
       if (count > 0) {
         count--;

test/pack.rb

@@ -145,3 +145,17 @@ assert 'pack/unpack "I"' do
   end
   assert_pack 'I', str, [12345]
 end
+
+assert 'pack/unpack "U"' do
+  assert_equal [], "".unpack("U")
+  assert_equal [], "".unpack("U*")
+  assert_equal [65, 66], "ABC".unpack("U2")
+  assert_equal [12371, 12435, 12395, 12385, 12399, 19990, 30028], "こんにちは世界".unpack("U*")
+
+  assert_equal "", [].pack("U")
+  assert_equal "", [].pack("U*")
+  assert_equal "AB", [65, 66, 67].pack("U2")
+  assert_equal "こんにちは世界", [12371, 12435, 12395, 12385, 12399, 19990, 30028].pack("U*")
+
+  assert_equal "\000", [0].pack("U")
+end