update string copy semantics to be undefined in a non-crashing way.

Change-Id: I03bb4db5931932280e368012cbaee6bef2854dd6

4 files changed, 58 insertions, 48 deletions

diff --git a/sal/inc/rtl/string.h b/sal/inc/rtl/string.h
index c38e106e6fdb..6dd42363b98a 100644
--- a/sal/inc/rtl/string.h
+++ b/sal/inc/rtl/string.h
@@ -889,6 +889,23 @@ SAL_DLLPUBLIC void SAL_CALL rtl_string_newFromStr( rtl_String ** newStr, const s
  */
 SAL_DLLPUBLIC void SAL_CALL rtl_string_newFromStr_WithLength( rtl_String ** newStr, const sal_Char * value, sal_Int32 len ) SAL_THROW_EXTERN_C();
 
+/** Allocate a new string that is a substring of this string.
+
+    The substring begins at the specified beginIndex and contains count
+    characters. Meaningless combinations such as negative beginIndex,
+    or beginIndex + count greater than the length of the string have
+    undefined behaviour.
+
+    @param     beginIndex   the beginning index, inclusive.
+    @param     count        the number of characters.
+    @return    the specified substring.
+
+    @since LibreOffice 3.7
+ */
+SAL_DLLPUBLIC void SAL_CALL rtl_string_newFromSubString(
+        rtl_String ** newStr, const rtl_String * from,
+        sal_Int32 beginIndex, sal_Int32 count ) SAL_THROW_EXTERN_C();
+
 /**
  @internal
  @since LibreOffice 3.6
diff --git a/sal/inc/rtl/string.hxx b/sal/inc/rtl/string.hxx
index 84ab48e05dc6..d58999b812f6 100644
--- a/sal/inc/rtl/string.hxx
+++ b/sal/inc/rtl/string.hxx
@@ -1024,31 +1024,27 @@ public:
     /**
       Returns a new string that is a substring of this string.
 
-      The substring begins at the specified beginIndex.  It is an error for
-      beginIndex to be negative or to be greater than the length of this string.
+      The substring begins at the specified beginIndex. If
+      beginIndex is negative or be greater than the length of
+      this string, behaviour is undefined.
 
       @param     beginIndex   the beginning index, inclusive.
       @return    the specified substring.
     */
     OString copy( sal_Int32 beginIndex ) const SAL_THROW(())
     {
-        assert(beginIndex >= 0 && beginIndex <= getLength());
-        if ( beginIndex == 0 )
-            return *this;
-        else
-        {
-            rtl_String* pNew = 0;
-            rtl_string_newFromStr_WithLength( &pNew, pData->buffer+beginIndex, getLength()-beginIndex );
-            return OString( pNew, (DO_NOT_ACQUIRE*)0 );
-        }
+        rtl_String *pNew = 0;
+        rtl_string_newFromSubString( &pNew, pData, beginIndex, getLength() - beginIndex );
+        return OString( pNew, (DO_NOT_ACQUIRE*)0 );
     }
 
     /**
       Returns a new string that is a substring of this string.
 
       The substring begins at the specified beginIndex and contains count
-      characters.  It is an error for either beginIndex or count to be negative,
-      or for beginIndex + count to be greater than the length of this string.
+      characters.  If either beginIndex or count are negative,
+      or beginIndex + count are greater than the length of this string
+      then behaviour is undefined.
 
       @param     beginIndex   the beginning index, inclusive.
       @param     count        the number of characters.
@@ -1056,17 +1052,9 @@ public:
     */
     OString copy( sal_Int32 beginIndex, sal_Int32 count ) const SAL_THROW(())
     {
-        assert(beginIndex >= 0 && beginIndex <= getLength() && count >= 0
-                && sal::static_int_cast<sal_uInt32>(count) <=
-                   sal::static_int_cast<sal_uInt32>(getLength() - beginIndex));
-        if ( (beginIndex == 0) && (count == getLength()) )
-            return *this;
-        else
-        {
-            rtl_String* pNew = 0;
-            rtl_string_newFromStr_WithLength( &pNew, pData->buffer+beginIndex, count );
-            return OString( pNew, (DO_NOT_ACQUIRE*)0 );
-        }
+        rtl_String *pNew = 0;
+        rtl_string_newFromSubString( &pNew, pData, beginIndex, count );
+        return OString( pNew, (DO_NOT_ACQUIRE*)0 );
     }
 
     /**
diff --git a/sal/inc/rtl/ustring.h b/sal/inc/rtl/ustring.h
index 5b4982ec1461..231dcdce253a 100644
--- a/sal/inc/rtl/ustring.h
+++ b/sal/inc/rtl/ustring.h
@@ -1226,6 +1226,23 @@ SAL_DLLPUBLIC void SAL_CALL rtl_uString_newFromStr(
 SAL_DLLPUBLIC void SAL_CALL rtl_uString_newFromStr_WithLength(
         rtl_uString ** newStr, const sal_Unicode * value, sal_Int32 len ) SAL_THROW_EXTERN_C();
 
+/** Allocate a new string that is a substring of this string.
+
+    The substring begins at the specified beginIndex and contains count
+    characters. Meaningless combinations such as negative beginIndex,
+    or beginIndex + count greater than the length of the string have
+    undefined behaviour.
+
+    @param     beginIndex   the beginning index, inclusive.
+    @param     count        the number of characters.
+    @return    the specified substring.
+
+    @since LibreOffice 3.7
+ */
+SAL_DLLPUBLIC void SAL_CALL rtl_uString_newFromSubString(
+        rtl_uString ** newStr, const rtl_uString * from,
+        sal_Int32 beginIndex, sal_Int32 count ) SAL_THROW_EXTERN_C();
+
 /** Allocate a new string that contains a copy of a character array.
 
     If the length of value is greater than zero, the reference count of the
diff --git a/sal/inc/rtl/ustring.hxx b/sal/inc/rtl/ustring.hxx
index b008054e17e3..e12a4b0b6256 100644
--- a/sal/inc/rtl/ustring.hxx
+++ b/sal/inc/rtl/ustring.hxx
@@ -1340,31 +1340,27 @@ public:
     /**
       Returns a new string that is a substring of this string.
 
-      The substring begins at the specified beginIndex.  It is an error for
-      beginIndex to be negative or to be greater than the length of this string.
+      The substring begins at the specified beginIndex. If
+      beginIndex is negative or be greater than the length of
+      this string, behaviour is undefined.
 
       @param     beginIndex   the beginning index, inclusive.
       @return    the specified substring.
     */
     OUString copy( sal_Int32 beginIndex ) const SAL_THROW(())
     {
-        assert(beginIndex >= 0 && beginIndex <= getLength());
-        if ( beginIndex == 0 )
-            return *this;
-        else
-        {
-            rtl_uString* pNew = 0;
-            rtl_uString_newFromStr_WithLength( &pNew, pData->buffer+beginIndex, getLength()-beginIndex );
-            return OUString( pNew, (DO_NOT_ACQUIRE*)0 );
-        }
+        rtl_uString *pNew = 0;
+        rtl_uString_newFromSubString( &pNew, pData, beginIndex, getLength() - beginIndex );
+        return OUString( pNew, (DO_NOT_ACQUIRE*)0 );
     }
 
     /**
       Returns a new string that is a substring of this string.
 
       The substring begins at the specified beginIndex and contains count
-      characters.  It is an error for either beginIndex or count to be negative,
-      or for beginIndex + count to be greater than the length of this string.
+      characters.  If either beginIndex or count are negative,
+      or beginIndex + count are greater than the length of this string
+      then behaviour is undefined.
 
       @param     beginIndex   the beginning index, inclusive.
       @param     count        the number of characters.
@@ -1372,17 +1368,9 @@ public:
     */
     OUString copy( sal_Int32 beginIndex, sal_Int32 count ) const SAL_THROW(())
     {
-        assert(beginIndex >= 0 && beginIndex <= getLength() && count >= 0
-               && sal::static_int_cast< sal_uInt32 >(count) <=
-                  sal::static_int_cast< sal_uInt32 >(getLength() - beginIndex));
-        if ( (beginIndex == 0) && (count == getLength()) )
-            return *this;
-        else
-        {
-            rtl_uString* pNew = 0;
-            rtl_uString_newFromStr_WithLength( &pNew, pData->buffer+beginIndex, count );
-            return OUString( pNew, (DO_NOT_ACQUIRE*)0 );
-        }
+        rtl_uString *pNew = 0;
+        rtl_uString_newFromSubString( &pNew, pData, beginIndex, count );
+        return OUString( pNew, (DO_NOT_ACQUIRE*)0 );
     }
 
     /**