Don't check for overlapping in strncpy/stpncpy for now

They check overlap across the whole range of the given length, but
the given length is not what will actually be copied, rather it's
the maximum length (if src is shorter, only length of src will be
copied). This triggers false positives and traps where it shouldn't
(e.g. in ICU tests).

Reported-by: q66

1 files changed, 14 insertions, 0 deletions

diff --git a/include/string.h b/include/string.h
index 778d22a..925e572 100644
--- a/include/string.h
+++ b/include/string.h
@@ -189,8 +189,15 @@ _FORTIFY_FN(stpncpy) char *stpncpy(char * _FORTIFY_POS0 __d, const char *__s,
 #if __has_builtin(__builtin___stpncpy_chk) && USE_NATIVE_CHK
         return __builtin___stpncpy_chk(__d, __s, __n, __fh_bos(__d, 0));
 #else
+#if 0
+        // They check overlap across the whole range of the given length, but
+        // the given length is not what will actually be copied, rather it's
+        // the maximum length (if src is shorter, only length of src will be
+        // copied). This triggers false positives and traps where it shouldn't
+        // (e.g. in ICU tests).
         if (__fh_overlap(__d, __s, __n))
                 __builtin_trap();
+#endif
 
         __fh_size_t __b = __fh_bos(__d, 0);
         if (__n > __b && strlen(__s) + 1 > __b)
@@ -290,8 +297,15 @@ _FORTIFY_FN(strncpy) char *strncpy(char * _FORTIFY_POS0 __d,
 #if __has_builtin(__builtin___strncpy_chk) && USE_NATIVE_CHK
         return __builtin___strncpy_chk(__d, __s, __n, __fh_bos(__d, 0));
 #else
+#if 0
+        // They check overlap across the whole range of the given length, but
+        // the given length is not what will actually be copied, rather it's
+        // the maximum length (if src is shorter, only length of src will be
+        // copied). This triggers false positives and traps where it shouldn't
+        // (e.g. in ICU tests).
         if (__fh_overlap(__d, __s, __n))
                 __builtin_trap();
+#endif
 
         __fh_size_t __b = __fh_bos(__d, 0);
         if (__n > __b)