fixup! fix(formData): Stop encoding values to calculate length

Author: FreeMasen

builtins/web/form-data/form-data-encoder.cpp

@@ -14,6 +14,7 @@
 #include "mozilla/ResultVariant.h"
 
 #include <fmt/format.h>
+#include <optional>
 #include <string>
 
 namespace {
@@ -48,24 +49,41 @@ std::optional<size_t> compute_unencoded_normalized_len(JSContext *cx, JS::Handle
   if (!linear) {
       return std::nullopt;
   }
-  auto len = JS::GetDeflatedUTF8StringLength(linear);
-  size_t two_byte_length = JS::GetLinearStringLength(linear);
-  for (size_t i = 0; i < two_byte_length; i++) {
-    char16_t ch = JS::GetLinearStringCharAt(linear, i);
-
-    if (ch == CR) {
-      if (i+1 < two_byte_length) {
-        char16_t next = JS::GetLinearStringCharAt(linear, i+1);
-        if (next == LF) {
-          i += 1;
-          // the character is already accounted for
-          continue;
+  auto extra_bytes_needed = [](const auto *chars, const auto len) {
+    size_t extra = 0;
+    for (size_t i = 0; i < len; i++) {
+      auto ch = chars[i];
+      if (ch == CR) {
+        if (i+1 < len) {
+          char16_t next = chars[i+1];
+          if (next == LF) {
+            i += 1;
+            // the character is already accounted for
+            continue;
+          }
         }
+        extra += 1;
+      } else if (ch == LF) {
+          extra += 1;
       }
-      len += 1;
-    } else if (ch == LF) {
-      len += 1; // CRLF
     }
+    return extra;
+  };
+  auto len = JS::GetDeflatedUTF8StringLength(linear);
+  size_t chars_len = JS::GetLinearStringLength(linear);
+  JS::AutoCheckCannotGC nogc;
+  if (JS::LinearStringHasLatin1Chars(linear)) {
+    auto chars = JS::GetLatin1LinearStringChars(nogc, linear);
+    if (!chars) {
+      return std::nullopt;
+    }
+    len += extra_bytes_needed(chars, chars_len);
+  } else {
+    auto chars = JS::GetTwoByteLinearStringChars(nogc, linear);
+    if (!chars) {
+      return std::nullopt;
+    }
+    len += extra_bytes_needed(chars, chars_len);
   }
   return len;
 }