Bug 1490609: Add JS_EncodeStringToASCII to CharacterEncoding.h. r=Waldo

js/public/CharacterEncoding.h

@@ -368,4 +368,23 @@ JS_EncodeStringToLatin1(JSContext* cx, JSString* str);
 extern JS_PUBLIC_API(JS::UniqueChars)
 JS_EncodeStringToUTF8(JSContext* cx, JS::Handle<JSString*> str);
 
+/**
+ * DEPRECATED
+ *
+ * Same behavior as JS_EncodeStringToLatin1(), but encode into an ASCII string.
+ *
+ * This function asserts in debug mode that the input string contains only
+ * ASCII characters.
+ *
+ * The returned string is also subject to misinterpretation if |str| contains
+ * any nulls (which are faithfully transcribed into the returned string, but
+ * which will implicitly truncate the string if it's passed to functions that
+ * expect null-terminated strings).
+ *
+ * Avoid using this function if possible, because we'll remove it once we can
+ * devise a better API for the task.
+ */
+extern JS_PUBLIC_API(JS::UniqueChars)
+JS_EncodeStringToASCII(JSContext* cx, JSString* str);
+
 #endif /* js_CharacterEncoding_h */

js/src/builtin/TestingFunctions.cpp

@@ -5016,7 +5016,17 @@ SetTimeZone(JSContext* cx, unsigned argc, Value* vp)
     };
 
     if (args[0].isString() && !args[0].toString()->empty()) {
-        UniqueChars timeZone = JS_EncodeStringToLatin1(cx, args[0].toString());
+        RootedLinearString str(cx, args[0].toString()->ensureLinear(cx));
+        if (!str) {
+            return false;
+        }
+
+        if (!StringIsAscii(str)) {
+            ReportUsageErrorASCII(cx, callee, "First argument contains non-ASCII characters");
+            return false;
+        }
+
+        UniqueChars timeZone = JS_EncodeStringToASCII(cx, str);
         if (!timeZone) {
             return false;
         }
@@ -5081,38 +5091,31 @@ SetDefaultLocale(JSContext* cx, unsigned argc, Value* vp)
     }
 
     if (args[0].isString() && !args[0].toString()->empty()) {
-        auto containsOnlyValidBCP47Characters = [](auto* chars, size_t length) {
-            return mozilla::IsAsciiAlpha(chars[0]) &&
-                   std::all_of(chars, chars + length, [](auto c) {
-                       return mozilla::IsAsciiAlphanumeric(c) || c == '-';
-                   });
-        };
-
         RootedLinearString str(cx, args[0].toString()->ensureLinear(cx));
         if (!str) {
             return false;
         }
 
-        bool hasValidChars;
-        {
-            JS::AutoCheckCannotGC nogc;
-
-            size_t length = str->length();
-            hasValidChars = str->hasLatin1Chars()
-                            ? containsOnlyValidBCP47Characters(str->latin1Chars(nogc), length)
-                            : containsOnlyValidBCP47Characters(str->twoByteChars(nogc), length);
-        }
-
-        if (!hasValidChars) {
-            ReportUsageErrorASCII(cx, callee, "First argument should be BCP47 language tag");
+        if (!StringIsAscii(str)) {
+            ReportUsageErrorASCII(cx, callee, "First argument contains non-ASCII characters");
             return false;
         }
 
-        UniqueChars locale = JS_EncodeStringToLatin1(cx, str);
+        UniqueChars locale = JS_EncodeStringToASCII(cx, str);
         if (!locale) {
             return false;
         }
 
+        bool containsOnlyValidBCP47Characters = mozilla::IsAsciiAlpha(locale[0]) &&
+            std::all_of(locale.get(), locale.get() + str->length(), [](auto c) {
+                return mozilla::IsAsciiAlphanumeric(c) || c == '-';
+            });
+
+        if (!containsOnlyValidBCP47Characters) {
+            ReportUsageErrorASCII(cx, callee, "First argument should be a BCP47 language tag");
+            return false;
+        }
+
         if (!JS_SetDefaultLocale(cx->runtime(), locale.get())) {
             ReportOutOfMemory(cx);
             return false;

js/src/builtin/intl/CommonFunctions.cpp

@@ -91,27 +91,22 @@ js::intl::ReportInternalError(JSContext* cx)
 js::UniqueChars
 js::intl::EncodeLocale(JSContext* cx, JSString* locale)
 {
-#ifdef DEBUG
-    auto containsOnlyValidBCP47Chars = [](auto* chars, size_t length) {
-        return length > 0 &&
-               mozilla::IsAsciiAlpha(chars[0]) &&
-               std::all_of(chars, chars + length, [](auto c) {
-                   return mozilla::IsAsciiAlphanumeric(c) || c == '-';
-               });
-    };
+    MOZ_ASSERT(locale->length() > 0);
 
-    if (JSLinearString* linear = locale->ensureLinear(cx)) {
-        JS::AutoCheckCannotGC nogc;
-        MOZ_ASSERT(linear->hasLatin1Chars()
-                   ? containsOnlyValidBCP47Chars(linear->latin1Chars(nogc), linear->length())
-                   : containsOnlyValidBCP47Chars(linear->twoByteChars(nogc), linear->length()));
-    } else {
-        // Ignore OOM when only performing a debug assertion.
-        cx->recoverFromOutOfMemory();
+    js::UniqueChars chars = EncodeAscii(cx, locale);
+
+#ifdef DEBUG
+    // Ensure the returned value contains only valid BCP 47 characters.
+    // (Lambdas can't be placed inside MOZ_ASSERT, so move the checks in an
+    // #ifdef block.)
+    if (chars) {
+        auto alnumOrDash = [](char c) { return mozilla::IsAsciiAlphanumeric(c) || c == '-'; };
+        MOZ_ASSERT(mozilla::IsAsciiAlpha(chars[0]));
+        MOZ_ASSERT(std::all_of(chars.get(), chars.get() + locale->length(), alnumOrDash));
     }
 #endif
 
-    return EncodeLatin1(cx, locale);
+    return chars;
 }
 
 bool

js/src/jsapi.cpp

@@ -6267,6 +6267,15 @@ JS_DecodeBytes(JSContext* cx, const char* src, size_t srclen, char16_t* dst, siz
     return true;
 }
 
+JS_PUBLIC_API(JS::UniqueChars)
+JS_EncodeStringToASCII(JSContext* cx, JSString* str)
+{
+    AssertHeapIsIdle();
+    CHECK_THREAD(cx);
+
+    return js::EncodeAscii(cx, str);
+}
+
 JS_PUBLIC_API(JS::UniqueChars)
 JS_EncodeStringToLatin1(JSContext* cx, JSString* str)
 {

js/src/jsnum.cpp

@@ -842,7 +842,7 @@ num_toLocaleString_impl(JSContext* cx, const CallArgs& args)
      * Create the string, move back to bytes to make string twiddling
      * a bit easier and so we can insert platform charset seperators.
      */
-    UniqueChars numBytes = JS_EncodeStringToLatin1(cx, str);
+    UniqueChars numBytes = EncodeAscii(cx, str);
     if (!numBytes) {
         return false;
     }

js/src/proxy/ScriptedProxyHandler.cpp

@@ -187,12 +187,12 @@ GetProxyTrap(JSContext* cx, HandleObject handler, HandlePropertyName name, Mutab
 
     // Step 4.
     if (!IsCallable(func)) {
-        UniqueChars bytes = EncodeLatin1(cx, name);
+        UniqueChars bytes = EncodeAscii(cx, name);
         if (!bytes) {
             return false;
         }
 
-        JS_ReportErrorNumberLatin1(cx, GetErrorMessage, nullptr, JSMSG_BAD_TRAP, bytes.get());
+        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_BAD_TRAP, bytes.get());
         return false;
     }
 

js/src/vm/Debugger.cpp

@@ -5069,6 +5069,16 @@ class MOZ_STACK_CLASS Debugger::ObjectQuery
                                           "neither undefined nor a string");
                 return false;
             }
+            JSLinearString* str = cls.toString()->ensureLinear(cx);
+            if (!str) {
+                return false;
+            }
+            if (!StringIsAscii(str)) {
+                JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_UNEXPECTED_TYPE,
+                                          "query object's 'class' property",
+                                          "not a string containing only ASCII characters");
+                return false;
+            }
             className = cls;
         }
         return true;
@@ -5197,7 +5207,7 @@ class MOZ_STACK_CLASS Debugger::ObjectQuery
      */
     bool prepareQuery() {
         if (className.isString()) {
-            classNameCString = JS_EncodeStringToLatin1(cx, className.toString());
+            classNameCString = JS_EncodeStringToASCII(cx, className.toString());
             if (!classNameCString) {
                 return false;
             }

js/src/vm/StringType.cpp

@@ -17,6 +17,8 @@
 #include "mozilla/TypeTraits.h"
 #include "mozilla/Unused.h"
 
+#include <algorithm>
+
 #include "jsfriendapi.h"
 
 #include "frontend/BytecodeCompiler.h"
@@ -1038,15 +1040,27 @@ js::CompareAtoms(JSAtom* atom1, JSAtom* atom2)
     return CompareStringsImpl(atom1, atom2);
 }
 
+bool
+js::StringIsAscii(JSLinearString* str)
+{
+    auto containsOnlyAsciiCharacters = [](const auto* chars, size_t length) {
+        return std::all_of(chars, chars + length, [](auto c) {
+            return mozilla::IsAscii(c);
+        });
+    };
+
+    JS::AutoCheckCannotGC nogc;
+    return str->hasLatin1Chars()
+           ? containsOnlyAsciiCharacters(str->latin1Chars(nogc), str->length())
+           : containsOnlyAsciiCharacters(str->twoByteChars(nogc), str->length());
+}
+
 bool
 js::StringEqualsAscii(JSLinearString* str, const char* asciiBytes)
 {
+    MOZ_ASSERT(JS::StringIsASCII(asciiBytes));
+
     size_t length = strlen(asciiBytes);
-#ifdef DEBUG
-    for (size_t i = 0; i != length; ++i) {
-        MOZ_ASSERT(unsigned(asciiBytes[i]) <= 127);
-    }
-#endif
     if (length != str->length()) {
         return false;
     }
@@ -2194,6 +2208,18 @@ js::EncodeLatin1(JSContext* cx, JSString* str)
     return UniqueChars(reinterpret_cast<char*>(buf));
 }
 
+UniqueChars
+js::EncodeAscii(JSContext* cx, JSString* str)
+{
+    JSLinearString* linear = str->ensureLinear(cx);
+    if (!linear) {
+        return nullptr;
+    }
+
+    MOZ_ASSERT(StringIsAscii(linear));
+    return EncodeLatin1(cx, linear);
+}
+
 UniqueChars
 js::IdToPrintableUTF8(JSContext* cx, HandleId id, IdToPrintableBehavior behavior)
 {

js/src/vm/StringType.h

@@ -1659,6 +1659,12 @@ CompareStrings(JSContext* cx, JSString* str1, JSString* str2, int32_t* result);
 extern int32_t
 CompareAtoms(JSAtom* atom1, JSAtom* atom2);
 
+/**
+ * Return true if the string contains only ASCII characters.
+ */
+extern bool
+StringIsAscii(JSLinearString* str);
+
 /*
  * Return true if the string matches the given sequence of ASCII bytes.
  */
@@ -1688,6 +1694,14 @@ SubstringKernel(JSContext* cx, HandleString str, int32_t beginInt, int32_t lengt
 
 /*** Conversions *********************************************************************************/
 
+/*
+ * Convert a string to a printable C string.
+ *
+ * Asserts if the input contains any non-ASCII characters.
+ */
+UniqueChars
+EncodeAscii(JSContext* cx, JSString* str);
+
 /*
  * Convert a string to a printable C string.
  */