Improve base64 decode and utf8 handling

html/js/utf8.js

@@ -0,0 +1,118 @@
+// ported from hterm.Terminal.IO.prototype.writeUTF8
+// https://chromium.googlesource.com/apps/libapps/+/master/hterm/js/hterm_terminal_io.js
+
+UTF8Decoder = function() {
+    this.bytesLeft = 0;
+    this.codePoint = 0;
+    this.lowerBound = 0;
+};
+
+UTF8Decoder.prototype.decode = function(str) {
+    var ret = '';
+    for (var i = 0; i < str.length; i++) {
+        var c = str.charCodeAt(i);
+        if (this.bytesLeft == 0) {
+            if (c <= 0x7F) {
+                ret += str.charAt(i);
+            } else if (0xC0 <= c && c <= 0xDF) {
+                this.codePoint = c - 0xC0;
+                this.bytesLeft = 1;
+                this.lowerBound = 0x80;
+            } else if (0xE0 <= c && c <= 0xEF) {
+                this.codePoint = c - 0xE0;
+                this.bytesLeft = 2;
+                this.lowerBound = 0x800;
+            } else if (0xF0 <= c && c <= 0xF7) {
+                this.codePoint = c - 0xF0;
+                this.bytesLeft = 3;
+                this.lowerBound = 0x10000;
+            } else if (0xF8 <= c && c <= 0xFB) {
+                this.codePoint = c - 0xF8;
+                this.bytesLeft = 4;
+                this.lowerBound = 0x200000;
+            } else if (0xFC <= c && c <= 0xFD) {
+                this.codePoint = c - 0xFC;
+                this.bytesLeft = 5;
+                this.lowerBound = 0x4000000;
+            } else {
+                ret += '\ufffd';
+            }
+        } else {
+            if (0x80 <= c && c <= 0xBF) {
+                this.bytesLeft--;
+                this.codePoint = (this.codePoint << 6) + (c - 0x80);
+                if (this.bytesLeft == 0) {
+                    var codePoint = this.codePoint;
+                    if (codePoint < this.lowerBound
+                        || (0xD800 <= codePoint && codePoint <= 0xDFFF)
+                        || codePoint > 0x10FFFF) {
+                        ret += '\ufffd';
+                    } else {
+                        if (codePoint < 0x10000) {
+                            ret += String.fromCharCode(codePoint);
+                        } else {
+                            codePoint -= 0x10000;
+                            ret += String.fromCharCode(
+                                0xD800 + ((codePoint >>> 10) & 0x3FF),
+                                0xDC00 + (codePoint & 0x3FF));
+                        }
+                    }
+                }
+            } else {
+                ret += '\ufffd';
+                this.bytesLeft = 0;
+                i--;
+            }
+        }
+    }
+    return ret;
+};
+
+Terminal.prototype.decodeUTF8 = function(str) {
+    return (new UTF8Decoder()).decode(str);
+};
+
+Terminal.prototype.encodeUTF8 = function(str) {
+    var ret = '';
+    for (var i = 0; i < str.length; i++) {
+        var c = str.charCodeAt(i);
+        if (0xDC00 <= c && c <= 0xDFFF) {
+            c = 0xFFFD;
+        } else if (0xD800 <= c && c <= 0xDBFF) {
+            if (i+1 < str.length) {
+                var d = str.charCodeAt(i+1);
+                if (0xDC00 <= d && d <= 0xDFFF) {
+                    c = 0x10000 + ((c & 0x3FF) << 10) + (d & 0x3FF);
+                    i++;
+                } else {
+                    c = 0xFFFD;
+                }
+            } else {
+                c = 0xFFFD;
+            }
+        }
+        var bytesLeft;
+        if (c <= 0x7F) {
+            ret += str.charAt(i);
+            continue;
+        } else if (c <= 0x7FF) {
+            ret += String.fromCharCode(0xC0 | (c >>> 6));
+            bytesLeft = 1;
+        } else if (c <= 0xFFFF) {
+            ret += String.fromCharCode(0xE0 | (c >>> 12));
+            bytesLeft = 2;
+        } else {
+            ret += String.fromCharCode(0xF0 | (c >>> 18));
+            bytesLeft = 3;
+        }
+        while (bytesLeft > 0) {
+            bytesLeft--;
+            ret += String.fromCharCode(0x80 | ((c >>> (6 * bytesLeft)) & 0x3F));
+        }
+    }
+    return ret;
+};
+
+Terminal.prototype.writeUTF8 = function (str) {
+    this.write(this.decodeUTF8(str));
+};