Split Java Access Bridge calls to fix NVDA crashes when selecting who…

…le text in specific source files in Android studio (#17604)

fixes #17418

Summary of the issue:
Nvda crashes when selecting whole text in specific source files in Android Studio and IntelliJ Idea

Description of user facing changes:
NVDA should no longer crash.

Description of development approach
Java Access Bridge has a buffer limit of 10240 characters for the text. If the text is too large to fit on this buffer size, NVDA will split the calls to take the buffer size in account.

Testing strategy:
Tested with IntelliJ idea and the file provided on the issue.

Known issues with pull request:
No known issues were identified.

source/JABHandler.py

@@ -647,7 +647,13 @@ def getAccessibleTextSelectionInfo(self):
 		bridgeDll.getAccessibleTextSelectionInfo(self.vmID, self.accContext, byref(textSelectionInfo))
 		return textSelectionInfo
 
-	def getAccessibleTextRange(self, start, end):
+	def _javaGetAccessibleTextRange(self, start: int, end: int) -> str:
+		"""Helper method that performs the Java Access Bridge call to obtain the text of this object based on a (start, end) range.
+
+		:param start: The start index to get from, inclusive.
+		:param end: The end index to fetch to, exclusive.
+		:return: the text within the given indices as a string.
+		"""
 		length = (end + 1) - start
 		if length <= 0:
 			return ""
@@ -656,6 +662,32 @@ def getAccessibleTextRange(self, start, end):
 		bridgeDll.getAccessibleTextRange(self.vmID, self.accContext, start, end, buf, length)
 		return textUtils.getTextFromRawBytes(buf.raw, numChars=length, encoding=textUtils.WCHAR_ENCODING)
 
+	# Constant gotten from AccessBridgePackages.h,
+	# minus one to accommodate the null character
+	MAX_BUFFER_SIZE = 10239
+
+	def getAccessibleTextRange(self, start: int, end: int) -> str:
+		"""Obtains the text of this object based on a (start, end) range.
+		If the text is too large to fit in the buffer, this method will split the Java Access Bridge calls in chunks to get the whole text.
+
+		:param start: The start index to get from, inclusive.
+		:param end: The end index to fetch to, exclusive.
+		:return: the text within the given indices as a string.
+		"""
+		length = (end + 1) - start
+		if length < self.MAX_BUFFER_SIZE:
+			# Fast path: perform the Java Access Bridge call directly
+			return self._javaGetAccessibleTextRange(start, end)
+
+		text = []
+		while start <= end:
+			bufferSize = min(self.MAX_BUFFER_SIZE, length)
+			text.append(self._javaGetAccessibleTextRange(start, start + bufferSize - 1))
+			start += bufferSize
+			length -= bufferSize
+
+		return "".join(text)
+
 	def getAccessibleTextLineBounds(self, index):
 		index = max(index, 0)
 		log.debug("lineBounds: index %s" % index)

user_docs/en/changes.md

@@ -55,6 +55,7 @@ Prefix matching on command line flags, e.g. using `--di` for `--disable-addons`
 
 ### Bug Fixes
 
+* NVDA will no longer crash when selecting all text in certain source files in Android Studio or IntelliJ Idea. (#17418, @thgcode)
 * Math reading has been fixed for some web elements.
 Specifically, MathML inside of span and other elements that have the attribute `role="math"`. (#15058)
 * Native support for the Dot Pad tactile graphics device from Dot Inc as a multiline braille display. (#17007)