From af7480d0190cb5dcf279a7ddfab320ff084a3471 Mon Sep 17 00:00:00 2001
From: jvoisin
Date: Thu, 22 Jun 2023 17:58:58 +0200
Subject: Add tests for stpcpy

---
 include/string.h | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

(limited to 'include/string.h')

diff --git a/include/string.h b/include/string.h
index f416a51..f738901 100644
--- a/include/string.h
+++ b/include/string.h
@@ -85,9 +85,16 @@ __access(write_only, 1)
 __access(read_only, 2)
 _FORTIFY_FN(stpcpy) char *stpcpy(char *__d, const char *__s)
 {
-	size_t __b = __bos(__d, 0);
+	size_t __n = strlen(__s) + 1;
 
-	if (strlen(__s) + 1 > __b)
+	/* trap if pointers are overlapping but not if dst == src.
+	 * gcc seems to like to generate code that relies on dst == src */
+	if ((__d < __s && __d + __n > __s) ||
+	    (__s < __d && __s + __n > __d))
+		__builtin_trap();
+
+	size_t __b = __bos(__d, 0);
+	if (__n > __b)
 		__builtin_trap();
 	return __orig_stpcpy(__d, __s);
 }
@@ -129,7 +136,7 @@ _FORTIFY_FN(strcpy) char *strcpy(char *__d, const char *__s)
 		__builtin_trap();
 
 	size_t __b = __bos(__d, 0);
-	if (strlen(__s) + 1 > __b)
+	if (__n > __b)
 		__builtin_trap();
 	return __orig_strcpy(__d, __s);
 }
-- 
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