[webcrypto] Reject failed operations with a DOMException rather than null.

Source/modules/crypto/NormalizeAlgorithm.cpp

Index: Source/modules/crypto/NormalizeAlgorithm.cpp
diff --git a/Source/modules/crypto/NormalizeAlgorithm.cpp b/Source/modules/crypto/NormalizeAlgorithm.cpp
index c18f469a0d784bb9a9b3d0ff6f30eec8c1e51b4b..8da1b28511c2020c22ab7626248803c91617ee33 100644
--- a/Source/modules/crypto/NormalizeAlgorithm.cpp
+++ b/Source/modules/crypto/NormalizeAlgorithm.cpp
@@ -279,6 +279,21 @@ bool lookupAlgorithmParamsType(blink::WebCryptoAlgorithmId id, AlgorithmOperatio
     return true;
 }
 
+void completeWithSyntaxError(const String& message, CryptoResult* result)
+{
+    result->completeWithError(blink::WebCryptoErrorTypeSyntax, message);
+}
+
+void completeWithNotSupportedError(const String& message, CryptoResult* result)
+{
+    result->completeWithError(blink::WebCryptoErrorTypeNotSupported, message);
+}
+
+void completeWithDataError(const String& message, CryptoResult* result)
+{
+    result->completeWithError(blink::WebCryptoErrorTypeData, message);
+}
+
 // ErrorContext holds a stack of string literals which describe what was
 // happening at the time the error occurred. This is helpful because
 // parsing of the algorithm dictionary can be recursive and it is difficult to
@@ -290,6 +305,11 @@ public:
         m_messages.append(message);
     }
 
+    void removeLast()
+    {
+        m_messages.removeLast();
+    }
+
     // Join all of the string literals into a single String.
     String toString() const
     {
@@ -339,7 +359,7 @@ private:
 //     typedef (ArrayBuffer or ArrayBufferView) CryptoOperationData;
 //
 // FIXME: Currently only supports ArrayBufferView.
-bool getOptionalCryptoOperationData(const Dictionary& raw, const char* propertyName, bool& hasProperty, RefPtr<ArrayBufferView>& buffer, const ErrorContext& context, String& errorDetails)
+bool getOptionalCryptoOperationData(const Dictionary& raw, const char* propertyName, bool& hasProperty, RefPtr<ArrayBufferView>& buffer, const ErrorContext& context, CryptoResult* result)
 {
     if (!raw.get(propertyName, buffer)) {
         hasProperty = false;
@@ -349,7 +369,7 @@ bool getOptionalCryptoOperationData(const Dictionary& raw, const char* propertyN
     hasProperty = true;
 
     if (!buffer) {
-        errorDetails = context.toString(propertyName, "Not an ArrayBufferView");
+        completeWithSyntaxError(context.toString(propertyName, "Not an ArrayBufferView"), result);
         return false;
     }
 
@@ -361,21 +381,21 @@ bool getOptionalCryptoOperationData(const Dictionary& raw, const char* propertyN
 //     typedef (ArrayBuffer or ArrayBufferView) CryptoOperationData;
 //
 // FIXME: Currently only supports ArrayBufferView.
-bool getCryptoOperationData(const Dictionary& raw, const char* propertyName, RefPtr<ArrayBufferView>& buffer, const ErrorContext& context, String& errorDetails)
+bool getCryptoOperationData(const Dictionary& raw, const char* propertyName, RefPtr<ArrayBufferView>& buffer, const ErrorContext& context, CryptoResult* result)
 {
     bool hasProperty;
-    bool ok = getOptionalCryptoOperationData(raw, propertyName, hasProperty, buffer, context, errorDetails);
+    bool ok = getOptionalCryptoOperationData(raw, propertyName, hasProperty, buffer, context, result);
     if (!hasProperty) {
-        errorDetails = context.toString(propertyName, "Missing required property");
+        completeWithSyntaxError(context.toString(propertyName, "Missing required property"), result);
         return false;
     }
     return ok;
 }
 
-bool getUint8Array(const Dictionary& raw, const char* propertyName, RefPtr<Uint8Array>& array, const ErrorContext& context, String& errorDetails)
+bool getUint8Array(const Dictionary& raw, const char* propertyName, RefPtr<Uint8Array>& array, const ErrorContext& context, CryptoResult* result)
 {
     if (!raw.get(propertyName, array) || !array) {
-        errorDetails = context.toString(propertyName, "Missing or not a Uint8Array");
+        completeWithSyntaxError(context.toString(propertyName, "Missing or not a Uint8Array"), result);
         return false;
     }
     return true;
@@ -384,25 +404,25 @@ bool getUint8Array(const Dictionary& raw, const char* propertyName, RefPtr<Uint8
 // Defined by the WebCrypto spec as:
 //
 //     typedef Uint8Array BigInteger;
-bool getBigInteger(const Dictionary& raw, const char* propertyName, RefPtr<Uint8Array>& array, const ErrorContext& context, String& errorDetails)
+bool getBigInteger(const Dictionary& raw, const char* propertyName, RefPtr<Uint8Array>& array, const ErrorContext& context, CryptoResult* result)
 {
-    if (!getUint8Array(raw, propertyName, array, context, errorDetails))
+    if (!getUint8Array(raw, propertyName, array, context, result))
         return false;
 
     if (!array->byteLength()) {
-        errorDetails = context.toString(propertyName, "BigInteger should not be empty");
+        completeWithSyntaxError(context.toString(propertyName, "BigInteger should not be empty"), result);
         return false;
     }
 
     if (!raw.get(propertyName, array) || !array) {
-        errorDetails = context.toString(propertyName, "Missing or not a Uint8Array");
+        completeWithSyntaxError(context.toString(propertyName, "Missing or not a Uint8Array"), result);
         return false;
     }
     return true;
 }
 
 // Gets an integer according to WebIDL's [EnforceRange].
-bool getOptionalInteger(const Dictionary& raw, const char* propertyName, bool& hasProperty, double& value, double minValue, double maxValue, const ErrorContext& context, String& errorDetails)
+bool getOptionalInteger(const Dictionary& raw, const char* propertyName, bool& hasProperty, double& value, double minValue, double maxValue, const ErrorContext& context, CryptoResult* result)
 {
     double number;
     bool ok = raw.get(propertyName, number, hasProperty);
@@ -411,14 +431,14 @@ bool getOptionalInteger(const Dictionary& raw, const char* propertyName, bool& h
         return true;
 
     if (!ok || std::isnan(number)) {
-        errorDetails = context.toString(propertyName, "Is not a number");
+        completeWithSyntaxError(context.toString(propertyName, "Is not a number"), result);
         return false;
     }
 
     number = trunc(number);
 
     if (std::isinf(number) || number < minValue || number > maxValue) {
-        errorDetails = context.toString(propertyName, "Outside of numeric range");
+        completeWithSyntaxError(context.toString(propertyName, "Outside of numeric range"), result);
         return false;
     }
 
@@ -426,51 +446,51 @@ bool getOptionalInteger(const Dictionary& raw, const char* propertyName, bool& h
     return true;
 }
 
-bool getInteger(const Dictionary& raw, const char* propertyName, double& value, double minValue, double maxValue, const ErrorContext& context, String& errorDetails)
+bool getInteger(const Dictionary& raw, const char* propertyName, double& value, double minValue, double maxValue, const ErrorContext& context, CryptoResult* result)
 {
     bool hasProperty;
-    if (!getOptionalInteger(raw, propertyName, hasProperty, value, minValue, maxValue, context, errorDetails))
+    if (!getOptionalInteger(raw, propertyName, hasProperty, value, minValue, maxValue, context, result))
         return false;
 
     if (!hasProperty) {
-        errorDetails = context.toString(propertyName, "Missing required property");
+        completeWithSyntaxError(context.toString(propertyName, "Missing required property"), result);
         return false;
     }
 
     return true;
 }
 
-bool getUint32(const Dictionary& raw, const char* propertyName, uint32_t& value, const ErrorContext& context, String& errorDetails)
+bool getUint32(const Dictionary& raw, const char* propertyName, uint32_t& value, const ErrorContext& context, CryptoResult* result)
 {
     double number;
-    if (!getInteger(raw, propertyName, number, 0, 0xFFFFFFFF, context, errorDetails))
+    if (!getInteger(raw, propertyName, number, 0, 0xFFFFFFFF, context, result))
         return false;
     value = number;
     return true;
 }
 
-bool getUint16(const Dictionary& raw, const char* propertyName, uint16_t& value, const ErrorContext& context, String& errorDetails)
+bool getUint16(const Dictionary& raw, const char* propertyName, uint16_t& value, const ErrorContext& context, CryptoResult* result)
 {
     double number;
-    if (!getInteger(raw, propertyName, number, 0, 0xFFFF, context, errorDetails))
+    if (!getInteger(raw, propertyName, number, 0, 0xFFFF, context, result))
         return false;
     value = number;
     return true;
 }
 
-bool getUint8(const Dictionary& raw, const char* propertyName, uint8_t& value, const ErrorContext& context, String& errorDetails)
+bool getUint8(const Dictionary& raw, const char* propertyName, uint8_t& value, const ErrorContext& context, CryptoResult* result)
 {
     double number;
-    if (!getInteger(raw, propertyName, number, 0, 0xFF, context, errorDetails))
+    if (!getInteger(raw, propertyName, number, 0, 0xFF, context, result))
         return false;
     value = number;
     return true;
 }
 
-bool getOptionalUint32(const Dictionary& raw, const char* propertyName, bool& hasValue, uint32_t& value, const ErrorContext& context, String& errorDetails)
+bool getOptionalUint32(const Dictionary& raw, const char* propertyName, bool& hasValue, uint32_t& value, const ErrorContext& context, CryptoResult* result)
 {
     double number;
-    if (!getOptionalInteger(raw, propertyName, hasValue, number, 0, 0xFFFFFFFF, context, errorDetails))
+    if (!getOptionalInteger(raw, propertyName, hasValue, number, 0, 0xFFFFFFFF, context, result))
         return false;
     if (hasValue)
         value = number;
@@ -482,14 +502,14 @@ bool getOptionalUint32(const Dictionary& raw, const char* propertyName, bool& ha
 //    dictionary AesCbcParams : Algorithm {
 //      CryptoOperationData iv;
 //    };
-bool parseAesCbcParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorithmParams>& params, const ErrorContext& context, String& errorDetails)
+bool parseAesCbcParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorithmParams>& params, const ErrorContext& context, CryptoResult* result)
 {
     RefPtr<ArrayBufferView> iv;
-    if (!getCryptoOperationData(raw, "iv", iv, context, errorDetails))
+    if (!getCryptoOperationData(raw, "iv", iv, context, result))
         return false;
 
     if (iv->byteLength() != 16) {
-        errorDetails = context.toString("iv", "Must be 16 bytes");
+        completeWithDataError(context.toString("iv", "Must be 16 bytes"), result);
         return false;
     }
 
@@ -502,28 +522,28 @@ bool parseAesCbcParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorithmPa
 //    dictionary AesKeyGenParams : Algorithm {
 //      [EnforceRange] unsigned short length;
 //    };
-bool parseAesKeyGenParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorithmParams>& params, const ErrorContext& context, String& errorDetails)
+bool parseAesKeyGenParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorithmParams>& params, const ErrorContext& context, CryptoResult* result)
 {
     uint16_t length;
-    if (!getUint16(raw, "length", length, context, errorDetails))
+    if (!getUint16(raw, "length", length, context, result))
         return false;
 
     params = adoptPtr(new blink::WebCryptoAesKeyGenParams(length));
     return true;
 }
 
-bool parseAlgorithm(const Dictionary&, AlgorithmOperation, blink::WebCryptoAlgorithm&, ErrorContext, String&);
+bool parseAlgorithm(const Dictionary&, AlgorithmOperation, blink::WebCryptoAlgorithm&, ErrorContext, CryptoResult*);
 
-bool parseHash(const Dictionary& raw, blink::WebCryptoAlgorithm& hash, ErrorContext context, String& errorDetails)
+bool parseHash(const Dictionary& raw, blink::WebCryptoAlgorithm& hash, ErrorContext context, CryptoResult* result)
 {
     Dictionary rawHash;
     if (!raw.get("hash", rawHash)) {
-        errorDetails = context.toString("hash", "Missing or not a dictionary");
+        completeWithSyntaxError(context.toString("hash", "Missing or not a dictionary"), result);
         return false;
     }
 
     context.add("hash");
-    return parseAlgorithm(rawHash, Digest, hash, context, errorDetails);
+    return parseAlgorithm(rawHash, Digest, hash, context, result);
 }
 
 // Defined by the WebCrypto spec as:
@@ -531,10 +551,10 @@ bool parseHash(const Dictionary& raw, blink::WebCryptoAlgorithm& hash, ErrorCont
 //    dictionary HmacImportParams : Algorithm {
 //      AlgorithmIdentifier hash;
 //    };
-bool parseHmacImportParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorithmParams>& params, const ErrorContext& context, String& errorDetails)
+bool parseHmacImportParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorithmParams>& params, const ErrorContext& context, CryptoResult* result)
 {
     blink::WebCryptoAlgorithm hash;
-    if (!parseHash(raw, hash, context, errorDetails))
+    if (!parseHash(raw, hash, context, result))
         return false;
 
     params = adoptPtr(new blink::WebCryptoHmacImportParams(hash));
@@ -550,15 +570,15 @@ bool parseHmacImportParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorit
 //      // size.
 //      unsigned long length;
 //    };
-bool parseHmacKeyGenParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorithmParams>& params, const ErrorContext& context, String& errorDetails)
+bool parseHmacKeyGenParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorithmParams>& params, const ErrorContext& context, CryptoResult* result)
 {
     blink::WebCryptoAlgorithm hash;
-    if (!parseHash(raw, hash, context, errorDetails))
+    if (!parseHash(raw, hash, context, result))
         return false;
 
     bool hasLength;
     uint32_t length = 0;
-    if (!getOptionalUint32(raw, "length", hasLength, length, context, errorDetails))
+    if (!getOptionalUint32(raw, "length", hasLength, length, context, result))
         return false;
 
     params = adoptPtr(new blink::WebCryptoHmacKeyGenParams(hash, hasLength, length));
@@ -570,10 +590,10 @@ bool parseHmacKeyGenParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorit
 //    dictionary RsaHashedImportParams {
 //      AlgorithmIdentifier hash;
 //    };
-bool parseRsaHashedImportParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorithmParams>& params, const ErrorContext& context, String& errorDetails)
+bool parseRsaHashedImportParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorithmParams>& params, const ErrorContext& context, CryptoResult* result)
 {
     blink::WebCryptoAlgorithm hash;
-    if (!parseHash(raw, hash, context, errorDetails))
+    if (!parseHash(raw, hash, context, result))
         return false;
 
     params = adoptPtr(new blink::WebCryptoRsaHashedImportParams(hash));
@@ -586,22 +606,22 @@ bool parseRsaHashedImportParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAl
 //      unsigned long modulusLength;
 //      BigInteger publicExponent;
 //    };
-bool parseRsaKeyGenParams(const Dictionary& raw, uint32_t& modulusLength, RefPtr<Uint8Array>& publicExponent, const ErrorContext& context, String& errorDetails)
+bool parseRsaKeyGenParams(const Dictionary& raw, uint32_t& modulusLength, RefPtr<Uint8Array>& publicExponent, const ErrorContext& context, CryptoResult* result)
 {
-    if (!getUint32(raw, "modulusLength", modulusLength, context, errorDetails))
+    if (!getUint32(raw, "modulusLength", modulusLength, context, result))
         return false;
 
-    if (!getBigInteger(raw, "publicExponent", publicExponent, context, errorDetails))
+    if (!getBigInteger(raw, "publicExponent", publicExponent, context, result))
         return false;
 
     return true;
 }
 
-bool parseRsaKeyGenParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorithmParams>& params, const ErrorContext& context, String& errorDetails)
+bool parseRsaKeyGenParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorithmParams>& params, const ErrorContext& context, CryptoResult* result)
 {
     uint32_t modulusLength;
     RefPtr<Uint8Array> publicExponent;
-    if (!parseRsaKeyGenParams(raw, modulusLength, publicExponent, context, errorDetails))
+    if (!parseRsaKeyGenParams(raw, modulusLength, publicExponent, context, result))
         return false;
 
     params = adoptPtr(new blink::WebCryptoRsaKeyGenParams(modulusLength, static_cast<const unsigned char*>(publicExponent->baseAddress()), publicExponent->byteLength()));
@@ -613,15 +633,15 @@ bool parseRsaKeyGenParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorith
 //    dictionary RsaHashedKeyGenParams : RsaKeyGenParams {
 //      AlgorithmIdentifier hash;
 //    };
-bool parseRsaHashedKeyGenParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorithmParams>& params, const ErrorContext& context, String& errorDetails)
+bool parseRsaHashedKeyGenParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorithmParams>& params, const ErrorContext& context, CryptoResult* result)
 {
     uint32_t modulusLength;
     RefPtr<Uint8Array> publicExponent;
-    if (!parseRsaKeyGenParams(raw, modulusLength, publicExponent, context, errorDetails))
+    if (!parseRsaKeyGenParams(raw, modulusLength, publicExponent, context, result))
         return false;
 
     blink::WebCryptoAlgorithm hash;
-    if (!parseHash(raw, hash, context, errorDetails))
+    if (!parseHash(raw, hash, context, result))
         return false;
 
     params = adoptPtr(new blink::WebCryptoRsaHashedKeyGenParams(hash, modulusLength, static_cast<const unsigned char*>(publicExponent->baseAddress()), publicExponent->byteLength()));
@@ -634,14 +654,14 @@ bool parseRsaHashedKeyGenParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAl
 //      CryptoOperationData counter;
 //      [EnforceRange] octet length;
 //    };
-bool parseAesCtrParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorithmParams>& params, const ErrorContext& context, String& errorDetails)
+bool parseAesCtrParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorithmParams>& params, const ErrorContext& context, CryptoResult* result)
 {
     RefPtr<ArrayBufferView> counter;
-    if (!getCryptoOperationData(raw, "counter", counter, context, errorDetails))
+    if (!getCryptoOperationData(raw, "counter", counter, context, result))
         return false;
 
     uint8_t length;
-    if (!getUint8(raw, "length", length, context, errorDetails))
+    if (!getUint8(raw, "length", length, context, result))
         return false;
 
     params = adoptPtr(new blink::WebCryptoAesCtrParams(length, static_cast<const unsigned char*>(counter->baseAddress()), counter->byteLength()));
@@ -655,20 +675,20 @@ bool parseAesCtrParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorithmPa
 //       CryptoOperationData? additionalData;
 //       [EnforceRange] octet? tagLength;  // May be 0-128
 //     }
-bool parseAesGcmParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorithmParams>& params, const ErrorContext& context, String& errorDetails)
+bool parseAesGcmParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorithmParams>& params, const ErrorContext& context, CryptoResult* result)
 {
     RefPtr<ArrayBufferView> iv;
-    if (!getCryptoOperationData(raw, "iv", iv, context, errorDetails))
+    if (!getCryptoOperationData(raw, "iv", iv, context, result))
         return false;
 
     bool hasAdditionalData;
     RefPtr<ArrayBufferView> additionalData;
-    if (!getOptionalCryptoOperationData(raw, "additionalData", hasAdditionalData, additionalData, context, errorDetails))
+    if (!getOptionalCryptoOperationData(raw, "additionalData", hasAdditionalData, additionalData, context, result))
         return false;
 
     double tagLength;
     bool hasTagLength;
-    if (!getOptionalInteger(raw, "tagLength", hasTagLength, tagLength, 0, 128, context, errorDetails))
+    if (!getOptionalInteger(raw, "tagLength", hasTagLength, tagLength, 0, 128, context, result))
         return false;
 
     const unsigned char* ivStart = static_cast<const unsigned char*>(iv->baseAddress());
@@ -681,38 +701,38 @@ bool parseAesGcmParams(const Dictionary& raw, OwnPtr<blink::WebCryptoAlgorithmPa
     return true;
 }
 
-bool parseAlgorithmParams(const Dictionary& raw, blink::WebCryptoAlgorithmParamsType type, OwnPtr<blink::WebCryptoAlgorithmParams>& params, ErrorContext& context, String& errorDetails)
+bool parseAlgorithmParams(const Dictionary& raw, blink::WebCryptoAlgorithmParamsType type, OwnPtr<blink::WebCryptoAlgorithmParams>& params, ErrorContext& context, CryptoResult* result)
 {
     switch (type) {
     case blink::WebCryptoAlgorithmParamsTypeNone:
         return true;
     case blink::WebCryptoAlgorithmParamsTypeAesCbcParams:
         context.add("AesCbcParams");
-        return parseAesCbcParams(raw, params, context, errorDetails);
+        return parseAesCbcParams(raw, params, context, result);
     case blink::WebCryptoAlgorithmParamsTypeAesKeyGenParams:
         context.add("AesKeyGenParams");
-        return parseAesKeyGenParams(raw, params, context, errorDetails);
+        return parseAesKeyGenParams(raw, params, context, result);
     case blink::WebCryptoAlgorithmParamsTypeHmacImportParams:
         context.add("HmacImportParams");
-        return parseHmacImportParams(raw, params, context, errorDetails);
+        return parseHmacImportParams(raw, params, context, result);
     case blink::WebCryptoAlgorithmParamsTypeHmacKeyGenParams:
         context.add("HmacKeyGenParams");
-        return parseHmacKeyGenParams(raw, params, context, errorDetails);
+        return parseHmacKeyGenParams(raw, params, context, result);
     case blink::WebCryptoAlgorithmParamsTypeRsaHashedKeyGenParams:
         context.add("RsaHashedKeyGenParams");
-        return parseRsaHashedKeyGenParams(raw, params, context, errorDetails);
+        return parseRsaHashedKeyGenParams(raw, params, context, result);
     case blink::WebCryptoAlgorithmParamsTypeRsaHashedImportParams:
         context.add("RsaHashedImportParams");
-        return parseRsaHashedImportParams(raw, params, context, errorDetails);
+        return parseRsaHashedImportParams(raw, params, context, result);
     case blink::WebCryptoAlgorithmParamsTypeRsaKeyGenParams:
         context.add("RsaKeyGenParams");
-        return parseRsaKeyGenParams(raw, params, context, errorDetails);
+        return parseRsaKeyGenParams(raw, params, context, result);
     case blink::WebCryptoAlgorithmParamsTypeAesCtrParams:
         context.add("AesCtrParams");
-        return parseAesCtrParams(raw, params, context, errorDetails);
+        return parseAesCtrParams(raw, params, context, result);
     case blink::WebCryptoAlgorithmParamsTypeAesGcmParams:
         context.add("AesGcmParams");
-        return parseAesGcmParams(raw, params, context, errorDetails);
+        return parseAesGcmParams(raw, params, context, result);
     case blink::WebCryptoAlgorithmParamsTypeRsaOaepParams:
         // TODO
         notImplemented();
@@ -722,37 +742,68 @@ bool parseAlgorithmParams(const Dictionary& raw, blink::WebCryptoAlgorithmParams
     return false;
 }
 
-bool parseAlgorithm(const Dictionary& raw, AlgorithmOperation op, blink::WebCryptoAlgorithm& algorithm, ErrorContext context, String& errorDetails)
+const char* operationToString(AlgorithmOperation op)
+{
+    switch (op) {
+    case Encrypt:
+        return "encrypt";
+    case Decrypt:
+        return "decrypt";
+    case Sign:
+        return "sign";
+    case Verify:
+        return "verify";
+    case Digest:
+        return "digest";
+    case GenerateKey:
+        return "generateKey";
+    case ImportKey:
+        return "importKey";
+    case DeriveKey:
+        return "deriveKey";
+    case WrapKey:
+        return "wrapKey";
+    case UnwrapKey:
+        return "unwrapKey";
+    }

[abarth-chromium, 2014/04/19 16:33:20]

Can we make this static data rather than code?

[eroman, 2014/04/21 20:39:10]

Sure, what kind of static data structure were you thinking?

My sense was that a switch statement on consecutive integers like this will
compile down to a flat data table as well. Using a switch is convenient since it
gives compile time error if not each case is handled.

+    return 0;
+}
+
+bool parseAlgorithm(const Dictionary& raw, AlgorithmOperation op, blink::WebCryptoAlgorithm& algorithm, ErrorContext context, CryptoResult* result)
 {
     context.add("Algorithm");
 
     if (!raw.isObject()) {
-        errorDetails = context.toString("Not an object");
+        completeWithSyntaxError(context.toString("Not an object"), result);
         return false;
     }
 
     String algorithmName;
     if (!raw.get("name", algorithmName)) {
-        errorDetails = context.toString("name", "Missing or not a string");
+        completeWithSyntaxError(context.toString("name", "Missing or not a string"), result);
         return false;
     }
 
     blink::WebCryptoAlgorithmId algorithmId;
     if (!lookupAlgorithmIdByName(algorithmName, algorithmId)) {
-        errorDetails = context.toString("Unrecognized algorithm name");
+        // FIXME: The spec says to return a SyntaxError if the input contains
+        //        any non-ASCII characters.
+        completeWithNotSupportedError(context.toString("Unrecognized name"), result);
         return false;
     }
 
-    context.add(algorithmIdToName(algorithmId));
+    // Remove the "Algorithm:" prefix for all subsequent errors.
+    context.removeLast();
 
     blink::WebCryptoAlgorithmParamsType paramsType;
     if (!lookupAlgorithmParamsType(algorithmId, op, paramsType)) {
-        errorDetails = context.toString("Unsupported operation");
+        context.add(algorithmIdToName(algorithmId));
+        completeWithNotSupportedError(context.toString("Unsupported operation", operationToString(op)), result);
         return false;
     }
 
     OwnPtr<blink::WebCryptoAlgorithmParams> params;
-    if (!parseAlgorithmParams(raw, paramsType, params, context, errorDetails))
+    if (!parseAlgorithmParams(raw, paramsType, params, context, result))
         return false;
 
     algorithm = blink::WebCryptoAlgorithm(algorithmId, params.release());
@@ -763,12 +814,7 @@ bool parseAlgorithm(const Dictionary& raw, AlgorithmOperation op, blink::WebCryp
 
 bool parseAlgorithm(const Dictionary& raw, AlgorithmOperation op, blink::WebCryptoAlgorithm& algorithm, CryptoResult* result)
 {
-    String errorDetails;
-    if (!parseAlgorithm(raw, op, algorithm, ErrorContext(), errorDetails)) {
-        result->completeWithError(errorDetails);
-        return false;
-    }
-    return true;
+    return parseAlgorithm(raw, op, algorithm, ErrorContext(), result);
 }
 
 const char* algorithmIdToName(blink::WebCryptoAlgorithmId id)