Bug 1028485 Don't set caret position over actual inserted string at commiting composition r=ehsan

editor/libeditor/base/IMETextTxn.cpp

@@ -224,6 +224,17 @@ IMETextTxn::SetSelectionForRanges()
   // Set caret position and selection of IME composition with TextRangeArray.
   bool setCaret = false;
   uint32_t countOfRanges = mRanges ? mRanges->Length() : 0;
+#ifdef DEBUG
+  // When this sets selection (caret) offset to out of the content of
+  // the editor, let's crash the process only on debug build.  That makes such
+  // bugs detectable with automated tests.
+  uint32_t maxOffset = UINT32_MAX;
+  mElement->GetLength(&maxOffset);
+#endif
+  // The mStringToInsert may be truncated if maxlength attribute value doesn't
+  // allow to input all text of this composition. So, we can get actual length
+  // of the inserted string from it.
+  uint32_t insertedLength = mStringToInsert.Length();
   for (uint32_t i = 0; i < countOfRanges; ++i) {
     const TextRange& textRange = mRanges->ElementAt(i);
 
@@ -232,9 +243,11 @@ IMETextTxn::SetSelectionForRanges()
     if (textRange.mRangeType == NS_TEXTRANGE_CARETPOSITION) {
       NS_ASSERTION(!setCaret, "The ranges already has caret position");
       NS_ASSERTION(!textRange.Length(), "nsEditor doesn't support wide caret");
-      // NOTE: If the caret position is larger than max length of the editor
-      //       content, this may fail.
-      rv = selection->Collapse(mElement, mOffset + textRange.mStartOffset);
+      int32_t caretOffset = static_cast<int32_t>(
+        mOffset + std::min(textRange.mStartOffset, insertedLength));
+      MOZ_ASSERT(caretOffset >= 0 &&
+                 static_cast<uint32_t>(caretOffset) <= maxOffset);
+      rv = selection->Collapse(mElement, caretOffset);
       setCaret = setCaret || NS_SUCCEEDED(rv);
       NS_ASSERTION(setCaret, "Failed to collapse normal selection");
       continue;
@@ -247,8 +260,16 @@ IMETextTxn::SetSelectionForRanges()
     }
 
     nsRefPtr<nsRange> clauseRange;
-    rv = nsRange::CreateRange(mElement, mOffset + textRange.mStartOffset,
-                              mElement, mOffset + textRange.mEndOffset,
+    int32_t startOffset = static_cast<int32_t>(
+      mOffset + std::min(textRange.mStartOffset, insertedLength));
+    MOZ_ASSERT(startOffset >= 0 &&
+               static_cast<uint32_t>(startOffset) <= maxOffset);
+    int32_t endOffset = static_cast<int32_t>(
+      mOffset + std::min(textRange.mEndOffset, insertedLength));
+    MOZ_ASSERT(endOffset >= startOffset &&
+               static_cast<uint32_t>(endOffset) <= maxOffset);
+    rv = nsRange::CreateRange(mElement, startOffset,
+                              mElement, endOffset,
                               getter_AddRefs(clauseRange));
     if (NS_FAILED(rv)) {
       NS_WARNING("Failed to create a DOM range for a clause of composition");
@@ -288,7 +309,10 @@ IMETextTxn::SetSelectionForRanges()
   // If the ranges doesn't include explicit caret position, let's set the
   // caret to the end of composition string.
   if (!setCaret) {
-    rv = selection->Collapse(mElement, mOffset + mStringToInsert.Length());
+    int32_t caretOffset = static_cast<int32_t>(mOffset + insertedLength);
+    MOZ_ASSERT(caretOffset >= 0 &&
+               static_cast<uint32_t>(caretOffset) <= maxOffset);
+    rv = selection->Collapse(mElement, caretOffset);
     NS_ASSERTION(NS_SUCCEEDED(rv),
                  "Failed to set caret at the end of composition string");
   }

editor/libeditor/text/tests/test_bug1026397.html

@@ -19,9 +19,6 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1026397
 <script type="application/javascript">
 
 /** Test for Bug 1026397 **/
-// Assertion fails at setting caret at committing composition string if it's cut by
-// maxlength and the caret position is out of the input element value.  See bug 1028485.
-SimpleTest.expectAssertions(10);
 SimpleTest.waitForExplicitFinish();
 
 function runTests()

widget/tests/test_composition_text_querycontent.xul

@@ -19,8 +19,6 @@
 <script class="testbody" type="application/javascript">
 <![CDATA[
 
-SimpleTest.expectAssertions(2);
-
 SimpleTest.waitForExplicitFinish();
 window.open("window_composition_text_querycontent.xul", "_blank", 
             "chrome,width=600,height=600");

widget/tests/window_composition_text_querycontent.xul

@@ -3443,6 +3443,95 @@ function runMaxLengthTest()
       !checkSelection(1 + 0, "", kDesc, "#3-4")) {
     return;
   }
+
+  // The input element whose content length is already maxlength and
+  // the carest is at start of the content.
+  input.value = "X";
+  input.selectionStart = input.selectionEnd = 0;
+
+  // start composition
+  synthesizeComposition({ type: "compositionstart" });
+
+  // input characters
+  synthesizeComposition({ type: "compositionupdate", data: "\u9B54" });
+  synthesizeText(
+    { "composition":
+      { "string": "\u9B54",
+        "clauses":
+        [
+          { "length": 1, "attr": COMPOSITION_ATTR_RAWINPUT }
+        ]
+      },
+      "caret": { "start": 1, "length": 0 }
+    });
+
+  if (!checkContent("\u9B54X", kDesc, "#4-1") ||
+      !checkSelection(1, "", kDesc, "#4-1")) {
+    return;
+  }
+
+  // commit the composition string
+  synthesizeComposition({ type: "compositionupdate", data: "\u9B54" });
+  synthesizeText(
+    { "composition":
+      { "string": "\u9B54",
+        "clauses":
+        [
+          { "length": 0, "attr": 0 }
+        ]
+      },
+      "caret": { "start": 1, "length": 0 }
+    });
+
+  // The input text must be discarded. Then, the caret position shouldn't be
+  // updated from its position at compositionstart.
+  if (!checkContent("X", kDesc, "#4-2") ||
+      !checkSelection(0, "", kDesc, "#4-2")) {
+    return;
+  }
+
+  synthesizeComposition({ type: "compositionend", data: "\u9B54" });
+
+  // start composition
+  synthesizeComposition({ type: "compositionstart" });
+
+  // input characters
+  synthesizeComposition({ type: "compositionupdate", data: "\u9B54\u6CD5" });
+  synthesizeText(
+    { "composition":
+      { "string": "\u9B54\u6CD5",
+        "clauses":
+        [
+          { "length": 2, "attr": COMPOSITION_ATTR_RAWINPUT }
+        ]
+      },
+      "caret": { "start": 2, "length": 0 }
+    });
+
+  if (!checkContent("\u9B54\u6CD5X", kDesc, "#5-1") ||
+      !checkSelection(2, "", kDesc, "#5-1")) {
+    return;
+  }
+
+  // commit the composition string
+  synthesizeComposition({ type: "compositionupdate", data: "\u9B54\u6CD5" });
+  synthesizeText(
+    { "composition":
+      { "string": "\u9B54\u6CD5",
+        "clauses":
+        [
+          { "length": 0, "attr": 0 }
+        ]
+      },
+      "caret": { "start": 2, "length": 0 }
+    });
+
+  if (!checkContent("X", kDesc, "#5-2") ||
+      !checkSelection(0, "", kDesc, "#5-2")) {
+    return;
+  }
+
+  synthesizeComposition({ type: "compositionend", data: "\u9B54\u6CD5" });
 }
 
 function runTest()