diff -r 000000000000 -r 6474c204b198 xpcom/io/nsLinebreakConverter.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/io/nsLinebreakConverter.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,122 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsLinebreakConverter_h_
+#define nsLinebreakConverter_h_
+
+#include "nscore.h"
+#include "nsString.h"
+
+// utility class for converting between different line breaks.
+
+class nsLinebreakConverter
+{
+public:
+
+  // Note: enum must match char* array in GetLinebreakString
+  typedef enum {
+    eLinebreakAny,          // any kind of linebreak (i.e. "don't care" source)
+    
+    eLinebreakPlatform,     // platform linebreak
+    eLinebreakContent,      // Content model linebreak (LF)
+    eLinebreakNet,          // Form submission linebreak (CRLF)
+  
+    eLinebreakMac,          // CR
+    eLinebreakUnix,         // LF
+    eLinebreakWindows,      // CRLF
+
+    eLinebreakSpace         // space characters. Only valid as destination type
+  
+  } ELinebreakType;
+
+  enum {
+    kIgnoreLen = -1
+  };
+  
+  /* ConvertLineBreaks
+   * Convert line breaks in the supplied string, allocating and returning
+   * a new buffer. Returns nullptr on failure.
+   * @param aSrc: the source string. if aSrcLen == kIgnoreLen this string is assumed
+   *              to be null terminated, otherwise it must be at least aSrcLen long.
+   * @param aSrcBreaks: the line breaks in the source. If unknown, pass eLinebreakAny.
+   *              If known, pass the known value, as this may be more efficient.
+   * @param aDestBreaks: the line breaks you want in the output.
+   * @param aSrcLen: length of the source. If -1, the source is assumed to be a null-
+   *              terminated string.
+   * @param aOutLen: used to return character length of returned buffer, if not null.
+   */
+  static char* ConvertLineBreaks(const char* aSrc,
+                ELinebreakType aSrcBreaks, ELinebreakType aDestBreaks,
+                int32_t aSrcLen = kIgnoreLen, int32_t* aOutLen = nullptr);
+  
+
+  /* ConvertUnicharLineBreaks
+   * Convert line breaks in the supplied string, allocating and returning
+   * a new buffer. Returns nullptr on failure.
+   * @param aSrc: the source string. if aSrcLen == kIgnoreLen this string is assumed
+   *              to be null terminated, otherwise it must be at least aSrcLen long.
+   * @param aSrcBreaks: the line breaks in the source. If unknown, pass eLinebreakAny.
+   *              If known, pass the known value, as this may be more efficient.
+   * @param aDestBreaks: the line breaks you want in the output.
+   * @param aSrcLen: length of the source, in characters. If -1, the source is assumed to be a null-
+   *              terminated string.
+   * @param aOutLen: used to return character length of returned buffer, if not null.
+   */
+  static char16_t* ConvertUnicharLineBreaks(const char16_t* aSrc,
+                ELinebreakType aSrcBreaks, ELinebreakType aDestBreaks,
+                int32_t aSrcLen = kIgnoreLen, int32_t* aOutLen = nullptr);
+  
+
+  /* ConvertStringLineBreaks
+   * Convert line breaks in the supplied string, changing the string buffer (i.e. in-place conversion)
+   * @param ioString: the string to be converted.
+   * @param aSrcBreaks: the line breaks in the source. If unknown, pass eLinebreakAny.
+   *              If known, pass the known value, as this may be more efficient.
+   * @param aDestBreaks: the line breaks you want in the output.
+   * @param aSrcLen: length of the source, in characters. If -1, the source is assumed to be a null-
+   *              terminated string.
+   */
+  static nsresult ConvertStringLineBreaks(nsString& ioString, ELinebreakType aSrcBreaks, ELinebreakType aDestBreaks);
+
+
+  /* ConvertLineBreaksInSitu
+   * Convert line breaks in place if possible. NOTE: THIS MAY REALLOCATE THE BUFFER,
+   * BUT IT WON'T FREE THE OLD BUFFER (because it doesn't know how). So be prepared
+   * to keep a copy of the old pointer, and free it if this passes back a new pointer.
+   * ALSO NOTE: DON'T PASS A STATIC STRING POINTER TO THIS FUNCTION.
+   * 
+   * @param ioBuffer: the source buffer. if aSrcLen == kIgnoreLen this string is assumed
+   *              to be null terminated, otherwise it must be at least aSrcLen long.
+   * @param aSrcBreaks: the line breaks in the source. If unknown, pass eLinebreakAny.
+   *              If known, pass the known value, as this may be more efficient.
+   * @param aDestBreaks: the line breaks you want in the output.
+   * @param aSrcLen: length of the source. If -1, the source is assumed to be a null-
+   *              terminated string.
+   * @param aOutLen: used to return character length of returned buffer, if not null.
+   */
+  static nsresult ConvertLineBreaksInSitu(char **ioBuffer, ELinebreakType aSrcBreaks, ELinebreakType aDestBreaks,
+                        int32_t aSrcLen = kIgnoreLen, int32_t* aOutLen = nullptr);
+
+
+  /* ConvertUnicharLineBreaksInSitu
+   * Convert line breaks in place if possible. NOTE: THIS MAY REALLOCATE THE BUFFER,
+   * BUT IT WON'T FREE THE OLD BUFFER (because it doesn't know how). So be prepared
+   * to keep a copy of the old pointer, and free it if this passes back a new pointer.
+   * 
+   * @param ioBuffer: the source buffer. if aSrcLen == kIgnoreLen this string is assumed
+   *              to be null terminated, otherwise it must be at least aSrcLen long.
+   * @param aSrcBreaks: the line breaks in the source. If unknown, pass eLinebreakAny.
+   *              If known, pass the known value, as this may be more efficient.
+   * @param aDestBreaks: the line breaks you want in the output.
+   * @param aSrcLen: length of the source in characters. If -1, the source is assumed to be a null-
+   *              terminated string.
+   * @param aOutLen: used to return character length of returned buffer, if not null.
+   */
+  static nsresult ConvertUnicharLineBreaksInSitu(char16_t **ioBuffer, ELinebreakType aSrcBreaks, ELinebreakType aDestBreaks,
+                        int32_t aSrcLen = kIgnoreLen, int32_t* aOutLen = nullptr);
+    
+};
+
+#endif // nsLinebreakConverter_h_