Add m-esr52 at 52.6.0

1 files changed, 748 insertions, 0 deletions

diff --git a/xpcom/string/nsXPCOMStrings.h b/xpcom/string/nsXPCOMStrings.h
new file mode 100644
index 000000000..493e092d6
--- /dev/null
+++ b/xpcom/string/nsXPCOMStrings.h
@@ -0,0 +1,748 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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 nsXPCOMStrings_h__
+#define nsXPCOMStrings_h__
+
+#include <string.h>
+#include "nscore.h"
+#include <limits>
+
+/**
+ * nsXPCOMStrings.h
+ *
+ * This file describes a minimal API for working with XPCOM's abstract
+ * string classes.  It divorces the consumer from having any run-time
+ * dependency on the implementation details of the abstract string types.
+ */
+
+#include "nscore.h"
+
+/* The base string types */
+class nsAString;
+class nsACString;
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * nsStringContainer
+ *
+ * This is an opaque data type that is large enough to hold the canonical
+ * implementation of nsAString.  The binary structure of this class is an
+ * implementation detail.
+ *
+ * The string data stored in a string container is always single fragment
+ * and may be null-terminated depending on how it is initialized.
+ *
+ * Typically, string containers are allocated on the stack for temporary
+ * use.  However, they can also be malloc'd if necessary.  In either case,
+ * a string container is not useful until it has been initialized with a
+ * call to NS_StringContainerInit.  The following example shows how to use
+ * a string container to call a function that takes a |nsAString &| out-param.
+ *
+ *   nsresult GetBlah(nsAString &aBlah);
+ *
+ *   nsresult MyCode()
+ *   {
+ *     nsresult rv;
+ *
+ *     nsStringContainer sc;
+ *     rv = NS_StringContainerInit(sc);
+ *     if (NS_FAILED(rv))
+ *       return rv;
+ *
+ *     rv = GetBlah(sc);
+ *     if (NS_SUCCEEDED(rv))
+ *     {
+ *       const char16_t *data;
+ *       NS_StringGetData(sc, &data);
+ *       //
+ *       // |data| now points to the result of the GetBlah function
+ *       //
+ *     }
+ *
+ *     NS_StringContainerFinish(sc);
+ *     return rv;
+ *   }
+ *
+ * The following example show how to use a string container to pass a string
+ * parameter to a function taking a |const nsAString &| in-param.
+ *
+ *   nsresult SetBlah(const nsAString &aBlah);
+ *
+ *   nsresult MyCode()
+ *   {
+ *     nsresult rv;
+ *
+ *     nsStringContainer sc;
+ *     rv = NS_StringContainerInit(sc);
+ *     if (NS_FAILED(rv))
+ *       return rv;
+ *
+ *     const char16_t kData[] = {'x','y','z','\0'};
+ *     rv = NS_StringSetData(sc, kData, sizeof(kData)/2 - 1);
+ *     if (NS_SUCCEEDED(rv))
+ *       rv = SetBlah(sc);
+ *
+ *     NS_StringContainerFinish(sc);
+ *     return rv;
+ *   }
+ */
+class nsStringContainer;
+
+
+/**
+ * This struct is never used directly. It is designed to have the same
+ * size as nsString. It can be stack and heap allocated and the internal
+ * functions cast it to nsString.
+ * While this practice is a strict aliasing violation, it doesn't seem to
+ * cause problems since the the struct is only accessed via the casts to
+ * nsString.
+ * We use protected instead of private to avoid compiler warnings about
+ * the members being unused.
+ */
+struct nsStringContainer_base
+{
+protected:
+  void* d1;
+  uint32_t d2;
+  uint32_t d3;
+};
+
+/**
+ * Flags that may be OR'd together to pass to NS_StringContainerInit2:
+ */
+enum
+{
+  /* Data passed into NS_StringContainerInit2 is not copied; instead, the
+   * string references the passed in data pointer directly.  The caller must
+   * ensure that the data is valid for the lifetime of the string container.
+   * This flag should not be combined with NS_STRING_CONTAINER_INIT_ADOPT. */
+  NS_STRING_CONTAINER_INIT_DEPEND    = (1 << 1),
+
+  /* Data passed into NS_StringContainerInit2 is not copied; instead, the
+   * string takes ownership over the data pointer.  The caller must have
+   * allocated the data array using the XPCOM memory allocator (nsMemory).
+   * This flag should not be combined with NS_STRING_CONTAINER_INIT_DEPEND. */
+  NS_STRING_CONTAINER_INIT_ADOPT     = (1 << 2),
+
+  /* Data passed into NS_StringContainerInit2 is a substring that is not
+   * null-terminated. */
+  NS_STRING_CONTAINER_INIT_SUBSTRING = (1 << 3)
+};
+
+/**
+ * NS_StringContainerInit
+ *
+ * @param aContainer    string container reference
+ * @return              NS_OK if string container successfully initialized
+ *
+ * This function may allocate additional memory for aContainer.  When
+ * aContainer is no longer needed, NS_StringContainerFinish should be called.
+ */
+XPCOM_API(nsresult) NS_StringContainerInit(nsStringContainer& aContainer);
+
+/**
+ * NS_StringContainerInit2
+ *
+ * @param aContainer    string container reference
+ * @param aData         character buffer (may be null)
+ * @param aDataLength   number of characters stored at aData (may pass
+ *                      UINT32_MAX if aData is null-terminated)
+ * @param aFlags        flags affecting how the string container is
+ *                      initialized.  this parameter is ignored when aData
+ *                      is null.  otherwise, if this parameter is 0, then
+ *                      aData is copied into the string.
+ *
+ * This function resembles NS_StringContainerInit but provides further
+ * options that permit more efficient memory usage.  When aContainer is
+ * no longer needed, NS_StringContainerFinish should be called.
+ *
+ * NOTE: NS_StringContainerInit2(container, nullptr, 0, 0) is equivalent to
+ * NS_StringContainerInit(container).
+ */
+XPCOM_API(nsresult) NS_StringContainerInit2(nsStringContainer& aContainer,
+                                            const char16_t* aData = nullptr,
+                                            uint32_t aDataLength = UINT32_MAX,
+                                            uint32_t aFlags = 0);
+
+/**
+ * NS_StringContainerFinish
+ *
+ * @param aContainer    string container reference
+ *
+ * This function frees any memory owned by aContainer.
+ */
+XPCOM_API(void) NS_StringContainerFinish(nsStringContainer& aContainer);
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * NS_StringGetData
+ *
+ * This function returns a const character pointer to the string's internal
+ * buffer, the length of the string, and a boolean value indicating whether
+ * or not the buffer is null-terminated.
+ *
+ * @param aStr          abstract string reference
+ * @param aData         out param that will hold the address of aStr's
+ *                      internal buffer
+ * @param aTerminated   if non-null, this out param will be set to indicate
+ *                      whether or not aStr's internal buffer is null-
+ *                      terminated
+ * @return              length of aStr's internal buffer
+ */
+XPCOM_API(uint32_t) NS_StringGetData(const nsAString& aStr,
+                                     const char16_t** aData,
+                                     bool* aTerminated = nullptr);
+
+/**
+ * NS_StringGetMutableData
+ *
+ * This function provides mutable access to a string's internal buffer.  It
+ * returns a pointer to an array of characters that may be modified.  The
+ * returned pointer remains valid until the string object is passed to some
+ * other string function.
+ *
+ * Optionally, this function may be used to resize the string's internal
+ * buffer.  The aDataLength parameter specifies the requested length of the
+ * string's internal buffer.  By passing some value other than UINT32_MAX,
+ * the caller can request that the buffer be resized to the specified number of
+ * characters before returning.  The caller is not responsible for writing a
+ * null-terminator.
+ *
+ * @param aStr          abstract string reference
+ * @param aDataLength   number of characters to resize the string's internal
+ *                      buffer to or UINT32_MAX if no resizing is needed
+ * @param aData         out param that upon return holds the address of aStr's
+ *                      internal buffer or null if the function failed
+ * @return              number of characters or zero if the function failed
+ *
+ * This function does not necessarily null-terminate aStr after resizing its
+ * internal buffer.  The behavior depends on the implementation of the abstract
+ * string, aStr.  If aStr is a reference to a nsStringContainer, then its data
+ * will be null-terminated by this function.
+ */
+XPCOM_API(uint32_t) NS_StringGetMutableData(nsAString& aStr,
+                                            uint32_t aDataLength,
+                                            char16_t** aData);
+
+/**
+ * NS_StringCloneData
+ *
+ * This function returns a null-terminated copy of the string's
+ * internal buffer.
+ *
+ * @param aStr          abstract string reference
+ * @return              null-terminated copy of the string's internal buffer
+ *                      (it must be free'd using using free)
+ */
+XPCOM_API(char16_t*) NS_StringCloneData(const nsAString& aStr);
+
+/**
+ * NS_StringSetData
+ *
+ * This function copies aData into aStr.
+ *
+ * @param aStr          abstract string reference
+ * @param aData         character buffer
+ * @param aDataLength   number of characters to copy from source string (pass
+ *                      UINT32_MAX to copy until end of aData, designated by
+ *                      a null character)
+ * @return              NS_OK if function succeeded
+ *
+ * This function does not necessarily null-terminate aStr after copying data
+ * from aData.  The behavior depends on the implementation of the abstract
+ * string, aStr.  If aStr is a reference to a nsStringContainer, then its data
+ * will be null-terminated by this function.
+ */
+XPCOM_API(nsresult) NS_StringSetData(nsAString& aStr, const char16_t* aData,
+                                     uint32_t aDataLength = UINT32_MAX);
+
+/**
+ * NS_StringSetDataRange
+ *
+ * This function copies aData into a section of aStr.  As a result it can be
+ * used to insert new characters into the string.
+ *
+ * @param aStr          abstract string reference
+ * @param aCutOffset    starting index where the string's existing data
+ *                      is to be overwritten (pass UINT32_MAX to cause
+ *                      aData to be appended to the end of aStr, in which
+ *                      case the value of aCutLength is ignored).
+ * @param aCutLength    number of characters to overwrite starting at
+ *                      aCutOffset (pass UINT32_MAX to overwrite until the
+ *                      end of aStr).
+ * @param aData         character buffer (pass null to cause this function
+ *                      to simply remove the "cut" range)
+ * @param aDataLength   number of characters to copy from source string (pass
+ *                      UINT32_MAX to copy until end of aData, designated by
+ *                      a null character)
+ * @return              NS_OK if function succeeded
+ *
+ * This function does not necessarily null-terminate aStr after copying data
+ * from aData.  The behavior depends on the implementation of the abstract
+ * string, aStr.  If aStr is a reference to a nsStringContainer, then its data
+ * will be null-terminated by this function.
+ */
+XPCOM_API(nsresult) NS_StringSetDataRange(nsAString& aStr,
+                                          uint32_t aCutOffset, uint32_t aCutLength,
+                                          const char16_t* aData,
+                                          uint32_t aDataLength = UINT32_MAX);
+
+/**
+ * NS_StringCopy
+ *
+ * This function makes aDestStr have the same value as aSrcStr.  It is
+ * provided as an optimization.
+ *
+ * @param aDestStr      abstract string reference to be modified
+ * @param aSrcStr       abstract string reference containing source string
+ * @return              NS_OK if function succeeded
+ *
+ * This function does not necessarily null-terminate aDestStr after copying
+ * data from aSrcStr.  The behavior depends on the implementation of the
+ * abstract string, aDestStr.  If aDestStr is a reference to a
+ * nsStringContainer, then its data will be null-terminated by this function.
+ */
+XPCOM_API(nsresult) NS_StringCopy(nsAString& aDestStr,
+                                  const nsAString& aSrcStr);
+
+/**
+ * NS_StringAppendData
+ *
+ * This function appends data to the existing value of aStr.
+ *
+ * @param aStr          abstract string reference to be modified
+ * @param aData         character buffer
+ * @param aDataLength   number of characters to append (pass UINT32_MAX to
+ *                      append until a null-character is encountered)
+ * @return              NS_OK if function succeeded
+ *
+ * This function does not necessarily null-terminate aStr upon completion.
+ * The behavior depends on the implementation of the abstract string, aStr.
+ * If aStr is a reference to a nsStringContainer, then its data will be null-
+ * terminated by this function.
+ */
+inline NS_HIDDEN_(nsresult)
+NS_StringAppendData(nsAString& aStr, const char16_t* aData,
+                    uint32_t aDataLength = UINT32_MAX)
+{
+  return NS_StringSetDataRange(aStr, UINT32_MAX, 0, aData, aDataLength);
+}
+
+/**
+ * NS_StringInsertData
+ *
+ * This function inserts data into the existing value of aStr at the specified
+ * offset.
+ *
+ * @param aStr          abstract string reference to be modified
+ * @param aOffset       specifies where in the string to insert aData
+ * @param aData         character buffer
+ * @param aDataLength   number of characters to append (pass UINT32_MAX to
+ *                      append until a null-character is encountered)
+ * @return              NS_OK if function succeeded
+ *
+ * This function does not necessarily null-terminate aStr upon completion.
+ * The behavior depends on the implementation of the abstract string, aStr.
+ * If aStr is a reference to a nsStringContainer, then its data will be null-
+ * terminated by this function.
+ */
+inline NS_HIDDEN_(nsresult)
+NS_StringInsertData(nsAString& aStr, uint32_t aOffset, const char16_t* aData,
+                    uint32_t aDataLength = UINT32_MAX)
+{
+  return NS_StringSetDataRange(aStr, aOffset, 0, aData, aDataLength);
+}
+
+/**
+ * NS_StringCutData
+ *
+ * This function shortens the existing value of aStr, by removing characters
+ * at the specified offset.
+ *
+ * @param aStr          abstract string reference to be modified
+ * @param aCutOffset    specifies where in the string to insert aData
+ * @param aCutLength    number of characters to remove
+ * @return              NS_OK if function succeeded
+ */
+inline NS_HIDDEN_(nsresult)
+NS_StringCutData(nsAString& aStr, uint32_t aCutOffset, uint32_t aCutLength)
+{
+  return NS_StringSetDataRange(aStr, aCutOffset, aCutLength, nullptr, 0);
+}
+
+/**
+ * NS_StringSetIsVoid
+ *
+ * This function marks a string as being a "void string".  Any data in the
+ * string will be lost.
+ */
+XPCOM_API(void) NS_StringSetIsVoid(nsAString& aStr, const bool aIsVoid);
+
+/**
+ * NS_StringGetIsVoid
+ *
+ * This function provides a way to test if a string is a "void string", as
+ * marked by NS_StringSetIsVoid.
+ */
+XPCOM_API(bool) NS_StringGetIsVoid(const nsAString& aStr);
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * nsCStringContainer
+ *
+ * This is an opaque data type that is large enough to hold the canonical
+ * implementation of nsACString.  The binary structure of this class is an
+ * implementation detail.
+ *
+ * The string data stored in a string container is always single fragment
+ * and may be null-terminated depending on how it is initialized.
+ *
+ * @see nsStringContainer for use cases and further documentation.
+ */
+class nsCStringContainer;
+
+/**
+ * Flags that may be OR'd together to pass to NS_StringContainerInit2:
+ */
+enum
+{
+  /* Data passed into NS_CStringContainerInit2 is not copied; instead, the
+   * string references the passed in data pointer directly.  The caller must
+   * ensure that the data is valid for the lifetime of the string container.
+   * This flag should not be combined with NS_CSTRING_CONTAINER_INIT_ADOPT. */
+  NS_CSTRING_CONTAINER_INIT_DEPEND    = (1 << 1),
+
+  /* Data passed into NS_CStringContainerInit2 is not copied; instead, the
+   * string takes ownership over the data pointer.  The caller must have
+   * allocated the data array using the XPCOM memory allocator (nsMemory).
+   * This flag should not be combined with NS_CSTRING_CONTAINER_INIT_DEPEND. */
+  NS_CSTRING_CONTAINER_INIT_ADOPT     = (1 << 2),
+
+  /* Data passed into NS_CStringContainerInit2 is a substring that is not
+   * null-terminated. */
+  NS_CSTRING_CONTAINER_INIT_SUBSTRING = (1 << 3)
+};
+
+/**
+ * NS_CStringContainerInit
+ *
+ * @param aContainer    string container reference
+ * @return              NS_OK if string container successfully initialized
+ *
+ * This function may allocate additional memory for aContainer.  When
+ * aContainer is no longer needed, NS_CStringContainerFinish should be called.
+ */
+XPCOM_API(nsresult) NS_CStringContainerInit(nsCStringContainer& aContainer);
+
+/**
+ * NS_CStringContainerInit2
+ *
+ * @param aContainer    string container reference
+ * @param aData         character buffer (may be null)
+ * @param aDataLength   number of characters stored at aData (may pass
+ *                      UINT32_MAX if aData is null-terminated)
+ * @param aFlags        flags affecting how the string container is
+ *                      initialized.  this parameter is ignored when aData
+ *                      is null.  otherwise, if this parameter is 0, then
+ *                      aData is copied into the string.
+ *
+ * This function resembles NS_CStringContainerInit but provides further
+ * options that permit more efficient memory usage.  When aContainer is
+ * no longer needed, NS_CStringContainerFinish should be called.
+ *
+ * NOTE: NS_CStringContainerInit2(container, nullptr, 0, 0) is equivalent to
+ * NS_CStringContainerInit(container).
+ */
+XPCOM_API(nsresult) NS_CStringContainerInit2(nsCStringContainer& aContainer,
+                                             const char* aData = nullptr,
+                                             uint32_t aDataLength = UINT32_MAX,
+                                             uint32_t aFlags = 0);
+
+/**
+ * NS_CStringContainerFinish
+ *
+ * @param aContainer    string container reference
+ *
+ * This function frees any memory owned by aContainer.
+ */
+XPCOM_API(void) NS_CStringContainerFinish(nsCStringContainer& aContainer);
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * NS_CStringGetData
+ *
+ * This function returns a const character pointer to the string's internal
+ * buffer, the length of the string, and a boolean value indicating whether
+ * or not the buffer is null-terminated.
+ *
+ * @param aStr          abstract string reference
+ * @param aData         out param that will hold the address of aStr's
+ *                      internal buffer
+ * @param aTerminated   if non-null, this out param will be set to indicate
+ *                      whether or not aStr's internal buffer is null-
+ *                      terminated
+ * @return              length of aStr's internal buffer
+ */
+XPCOM_API(uint32_t) NS_CStringGetData(const nsACString& aStr,
+                                      const char** aData,
+                                      bool* aTerminated = nullptr);
+
+/**
+ * NS_CStringGetMutableData
+ *
+ * This function provides mutable access to a string's internal buffer.  It
+ * returns a pointer to an array of characters that may be modified.  The
+ * returned pointer remains valid until the string object is passed to some
+ * other string function.
+ *
+ * Optionally, this function may be used to resize the string's internal
+ * buffer.  The aDataLength parameter specifies the requested length of the
+ * string's internal buffer.  By passing some value other than UINT32_MAX,
+ * the caller can request that the buffer be resized to the specified number of
+ * characters before returning.  The caller is not responsible for writing a
+ * null-terminator.
+ *
+ * @param aStr          abstract string reference
+ * @param aDataLength   number of characters to resize the string's internal
+ *                      buffer to or UINT32_MAX if no resizing is needed
+ * @param aData         out param that upon return holds the address of aStr's
+ *                      internal buffer or null if the function failed
+ * @return              number of characters or zero if the function failed
+ *
+ * This function does not necessarily null-terminate aStr after resizing its
+ * internal buffer.  The behavior depends on the implementation of the abstract
+ * string, aStr.  If aStr is a reference to a nsStringContainer, then its data
+ * will be null-terminated by this function.
+ */
+XPCOM_API(uint32_t) NS_CStringGetMutableData(nsACString& aStr,
+                                             uint32_t aDataLength,
+                                             char** aData);
+
+/**
+ * NS_CStringCloneData
+ *
+ * This function returns a null-terminated copy of the string's
+ * internal buffer.
+ *
+ * @param aStr          abstract string reference
+ * @return              null-terminated copy of the string's internal buffer
+ *                      (it must be free'd using using free)
+ */
+XPCOM_API(char*) NS_CStringCloneData(const nsACString& aStr);
+
+/**
+ * NS_CStringSetData
+ *
+ * This function copies aData into aStr.
+ *
+ * @param aStr          abstract string reference
+ * @param aData         character buffer
+ * @param aDataLength   number of characters to copy from source string (pass
+ *                      UINT32_MAX to copy until end of aData, designated by
+ *                      a null character)
+ * @return              NS_OK if function succeeded
+ *
+ * This function does not necessarily null-terminate aStr after copying data
+ * from aData.  The behavior depends on the implementation of the abstract
+ * string, aStr.  If aStr is a reference to a nsStringContainer, then its data
+ * will be null-terminated by this function.
+ */
+XPCOM_API(nsresult) NS_CStringSetData(nsACString& aStr, const char* aData,
+                                      uint32_t aDataLength = UINT32_MAX);
+
+/**
+ * NS_CStringSetDataRange
+ *
+ * This function copies aData into a section of aStr.  As a result it can be
+ * used to insert new characters into the string.
+ *
+ * @param aStr          abstract string reference
+ * @param aCutOffset    starting index where the string's existing data
+ *                      is to be overwritten (pass UINT32_MAX to cause
+ *                      aData to be appended to the end of aStr, in which
+ *                      case the value of aCutLength is ignored).
+ * @param aCutLength    number of characters to overwrite starting at
+ *                      aCutOffset (pass UINT32_MAX to overwrite until the
+ *                      end of aStr).
+ * @param aData         character buffer (pass null to cause this function
+ *                      to simply remove the "cut" range)
+ * @param aDataLength   number of characters to copy from source string (pass
+ *                      UINT32_MAX to copy until end of aData, designated by
+ *                      a null character)
+ * @return              NS_OK if function succeeded
+ *
+ * This function does not necessarily null-terminate aStr after copying data
+ * from aData.  The behavior depends on the implementation of the abstract
+ * string, aStr.  If aStr is a reference to a nsStringContainer, then its data
+ * will be null-terminated by this function.
+ */
+XPCOM_API(nsresult) NS_CStringSetDataRange(nsACString& aStr,
+                                           uint32_t aCutOffset,
+                                           uint32_t aCutLength,
+                                           const char* aData,
+                                           uint32_t aDataLength = UINT32_MAX);
+
+/**
+ * NS_CStringCopy
+ *
+ * This function makes aDestStr have the same value as aSrcStr.  It is
+ * provided as an optimization.
+ *
+ * @param aDestStr      abstract string reference to be modified
+ * @param aSrcStr       abstract string reference containing source string
+ * @return              NS_OK if function succeeded
+ *
+ * This function does not necessarily null-terminate aDestStr after copying
+ * data from aSrcStr.  The behavior depends on the implementation of the
+ * abstract string, aDestStr.  If aDestStr is a reference to a
+ * nsStringContainer, then its data will be null-terminated by this function.
+ */
+XPCOM_API(nsresult) NS_CStringCopy(nsACString& aDestStr,
+                                   const nsACString& aSrcStr);
+
+/**
+ * NS_CStringAppendData
+ *
+ * This function appends data to the existing value of aStr.
+ *
+ * @param aStr          abstract string reference to be modified
+ * @param aData         character buffer
+ * @param aDataLength   number of characters to append (pass UINT32_MAX to
+ *                      append until a null-character is encountered)
+ * @return              NS_OK if function succeeded
+ *
+ * This function does not necessarily null-terminate aStr upon completion.
+ * The behavior depends on the implementation of the abstract string, aStr.
+ * If aStr is a reference to a nsStringContainer, then its data will be null-
+ * terminated by this function.
+ */
+inline NS_HIDDEN_(nsresult)
+NS_CStringAppendData(nsACString& aStr, const char* aData,
+                     uint32_t aDataLength = UINT32_MAX)
+{
+  return NS_CStringSetDataRange(aStr, UINT32_MAX, 0, aData, aDataLength);
+}
+
+/**
+ * NS_CStringInsertData
+ *
+ * This function inserts data into the existing value of aStr at the specified
+ * offset.
+ *
+ * @param aStr          abstract string reference to be modified
+ * @param aOffset       specifies where in the string to insert aData
+ * @param aData         character buffer
+ * @param aDataLength   number of characters to append (pass UINT32_MAX to
+ *                      append until a null-character is encountered)
+ * @return              NS_OK if function succeeded
+ *
+ * This function does not necessarily null-terminate aStr upon completion.
+ * The behavior depends on the implementation of the abstract string, aStr.
+ * If aStr is a reference to a nsStringContainer, then its data will be null-
+ * terminated by this function.
+ */
+inline NS_HIDDEN_(nsresult)
+NS_CStringInsertData(nsACString& aStr, uint32_t aOffset, const char* aData,
+                     uint32_t aDataLength = UINT32_MAX)
+{
+  return NS_CStringSetDataRange(aStr, aOffset, 0, aData, aDataLength);
+}
+
+/**
+ * NS_CStringCutData
+ *
+ * This function shortens the existing value of aStr, by removing characters
+ * at the specified offset.
+ *
+ * @param aStr          abstract string reference to be modified
+ * @param aCutOffset    specifies where in the string to insert aData
+ * @param aCutLength    number of characters to remove
+ * @return              NS_OK if function succeeded
+ */
+inline NS_HIDDEN_(nsresult)
+NS_CStringCutData(nsACString& aStr, uint32_t aCutOffset, uint32_t aCutLength)
+{
+  return NS_CStringSetDataRange(aStr, aCutOffset, aCutLength, nullptr, 0);
+}
+
+/**
+ * NS_CStringSetIsVoid
+ *
+ * This function marks a string as being a "void string".  Any data in the
+ * string will be lost.
+ */
+XPCOM_API(void) NS_CStringSetIsVoid(nsACString& aStr, const bool aIsVoid);
+
+/**
+ * NS_CStringGetIsVoid
+ *
+ * This function provides a way to test if a string is a "void string", as
+ * marked by NS_CStringSetIsVoid.
+ */
+XPCOM_API(bool) NS_CStringGetIsVoid(const nsACString& aStr);
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * Encodings that can be used with the following conversion routines.
+ */
+enum nsCStringEncoding
+{
+  /* Conversion between ASCII and UTF-16 assumes that all bytes in the source
+   * string are 7-bit ASCII and can be inflated to UTF-16 by inserting null
+   * bytes.  Reverse conversion is done by truncating every other byte.  The
+   * conversion may result in loss and/or corruption of information if the
+   * strings do not strictly contain ASCII data. */
+  NS_CSTRING_ENCODING_ASCII = 0,
+
+  /* Conversion between UTF-8 and UTF-16 is non-lossy. */
+  NS_CSTRING_ENCODING_UTF8 = 1,
+
+  /* Conversion from UTF-16 to the native filesystem charset may result in a
+   * loss of information.  No attempt is made to protect against data loss in
+   * this case.  The native filesystem charset applies to strings passed to
+   * the "Native" method variants on nsIFile. */
+  NS_CSTRING_ENCODING_NATIVE_FILESYSTEM = 2
+};
+
+/**
+ * NS_CStringToUTF16
+ *
+ * This function converts the characters in a nsACString to an array of UTF-16
+ * characters, in the platform endianness.  The result is stored in a nsAString
+ * object.
+ *
+ * @param aSource       abstract string reference containing source string
+ * @param aSrcEncoding  character encoding of the source string
+ * @param aDest         abstract string reference to hold the result
+ */
+XPCOM_API(nsresult) NS_CStringToUTF16(const nsACString& aSource,
+                                      nsCStringEncoding aSrcEncoding,
+                                      nsAString& aDest);
+
+/**
+ * NS_UTF16ToCString
+ *
+ * This function converts the UTF-16 characters in a nsAString to a single-byte
+ * encoding.  The result is stored in a nsACString object.  In some cases this
+ * conversion may be lossy.  In such cases, the conversion may succeed with a
+ * return code indicating loss of information.  The exact behavior is not
+ * specified at this time.
+ *
+ * @param aSource       abstract string reference containing source string
+ * @param aDestEncoding character encoding of the resulting string
+ * @param aDest         abstract string reference to hold the result
+ */
+XPCOM_API(nsresult) NS_UTF16ToCString(const nsAString& aSource,
+                                      nsCStringEncoding aDestEncoding,
+                                      nsACString& aDest);
+
+#endif // nsXPCOMStrings_h__