Relax non-null requirement for some rtl_uString_* functions

...that take a pointer and a length, and where it should be OK that the pointer
is null if the length is zero.  Those rtl_uString_* functions are targets of
OUString member functions that take std::[u16]string_view arguments, and
19926ed35ebb623fc896942b1f232b83edf1fc1e "loplugin:stringview: Flag empty string
converted to string view" (which changed some call sites to pass in default-
constructed std::[u16]string_view, for which data() returns null) revealed that
those rtl_uString_* functions were not prepared for such input.

(The guardings of memcpy are necessary because memcpy still requires its pointer
arguments to be non-null, even if the corresponding length is zero.)

The new sal/qa/rtl/strings/test_strings_defaultstringview.cxx systematically
tests all O[U]String[Buffer] member functions taking std::[u16]string_view
arguments.  It revealed one further issue in
IMPL_RTL_STRNAME(compare_WithLength), where UBSan reported a
nullptr-with-nonzero-offset

> sal/rtl/strtmpl.cxx:149:9: runtime error: applying non-zero offset 18446744073709551614 to null pointer

Also, rtl_uString_newReplaceFirstUtf16LUtf16L was found to lack a check for its
`from` argument to be non-null.

Change-Id: I6a7a712570f7d1e8d52097208c8a43a5a24797af
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/106295
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

1 files changed, 8 insertions, 8 deletions

diff --git a/include/rtl/ustring.h b/include/rtl/ustring.h
index abd33bb77f15..9e61df974618 100644
--- a/include/rtl/ustring.h
+++ b/include/rtl/ustring.h
@@ -1495,8 +1495,8 @@ SAL_DLLPUBLIC void SAL_CALL rtl_uString_newConcatAsciiL(
 
     @param left a valid string.
 
-    @param right must not be null and must point to memory of at least
-    \p rightLength UTF-16 code units
+    @param right must point to memory of at least \p rightLength UTF-16 code units; may be null if
+    \p rigthLength is zero
 
     @param rightLength the length of the \p right string; must be non-negative
 
@@ -1763,13 +1763,13 @@ SAL_DLLPUBLIC void SAL_CALL rtl_uString_newReplaceFirstUtf16LAsciiL(
 
     @param str  pointer to the original string; must not be null
 
-    @param from  pointer to the substring to be replaced; must not be null and
-    must point to memory of at least \p fromLength UTF-16 code units
+    @param from  pointer to the substring to be replaced; must point to memory of at least
+    \p fromLength UTF-16 code units; may be null if \p toLength is zero
 
     @param fromLength  the length of the \p from substring; must be non-negative
 
-    @param to  pointer to the substring to be replaced; must not be null and
-    must point to memory of at least \p toLength UTF-16 code units
+    @param to  pointer to the substring to be replaced; must point to memory of at least \p toLength
+    UTF-16 code units; may be null if \p toLength is zero
 
     @param toLength  the length of the \p to substring; must be non-negative
 
@@ -1927,8 +1927,8 @@ SAL_DLLPUBLIC void SAL_CALL rtl_uString_newReplaceAllAsciiLAsciiL(
 
     @param fromLength  the length of the \p from substring; must be non-negative
 
-    @param to  pointer to the substring to be replaced; must not be null and
-    must point to memory of at least \p toLength UTF-16 code units
+    @param to  pointer to the substring to be replaced; must point to memory of at least \p toLength
+    UTF-16 code units; may be null if \p toLength is zero
 
     @param toLength  the length of the \p to substring; must be non-negative