fortify-headers

commit 6040b4a27409968c764353a98c45d972cfd89a8a
parent b9121e4d679b5fccb69abcb58b05a6be5c7191dc
Author: jvoisin <julien.voisin@dustri.org>
Date:   Thu, 30 Apr 2026 17:37:02 +0200

Fix a bug in stpncpy

The manpage says that stpncpy will "copy non-null bytes from the string pointed
to by src into the array pointed to by dst.", it doesn't add a terminal NULL
byte, so we shouldn't check for it.

Diffstat:
M
include/string.h
 | 
2
+-
M
tests/test_stpncpy_static_write.c
 | 
3
++-

2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/include/string.h b/include/string.h
@@ -104,7 +104,7 @@ _FORTIFY_FN(stpncpy) char *stpncpy(char * _FORTIFY_POS0 __d, const char *__s,
 {
 	size_t __b = __bos(__d, 0);
 
-	if (__n > __b && strlen(__s) + 1 > __b)
+	if (__n > __b)
 		__builtin_trap();
 	return __orig_stpncpy(__d, __s, __n);
 }
diff --git a/tests/test_stpncpy_static_write.c b/tests/test_stpncpy_static_write.c
@@ -4,7 +4,8 @@
 
 int main(int argc, char** argv) {
   char buffer[8] = {0};
-  stpncpy(buffer, "1234567", 5);
+  stpncpy(buffer, "1234567890", 5);
+  stpncpy(buffer, "1234567890", 8);
   puts(buffer);
 
   CHK_FAIL_START