13 files changed, 14 insertions, 1 deletions
diff --git a/src/string/memcmp.c b/src/string/memcmp.c
index 028d2354..f87f849a 100644
--- a/src/string/memcmp.c
+++ b/src/string/memcmp.c
@@ -12,6 +12,7 @@ int memcmp(const void *s1, const void *s2, size_t n)
 	SIGNAL_SAFE(0);
 	ASSERT_NONNULL(s1);
 	ASSERT_NONNULL(s2);
+	/* no modifications, so overlap is OK */
 
 	for (i = 0; i < n; i++) {
 		if (p[i] != q[i]) {
diff --git a/src/string/memmove_s.c b/src/string/memmove_s.c
index 0475ee00..a6d84b55 100644
--- a/src/string/memmove_s.c
+++ b/src/string/memmove_s.c
@@ -8,6 +8,7 @@ errno_t memmove_s(void *s1, rsize_t s1max, const void *s2, rsize_t n)
 	SIGNAL_SAFE(0);
 	ASSERT_NONNULL(s1);
 	ASSERT_NONNULL(s2);
+	/* Overlap is explicitly allowed */
 
 	if (n > s1max) {
 		/* do the right thing */
diff --git a/src/string/strcmp.c b/src/string/strcmp.c
index 8c679f4b..58102d79 100644
--- a/src/string/strcmp.c
+++ b/src/string/strcmp.c
@@ -8,6 +8,7 @@ int strcmp(const char *s1, const char *s2)
 	SIGNAL_SAFE(0);
 	ASSERT_NONNULL(s1);
 	ASSERT_NONNULL(s2);
+	/* no modifcation, overlap is OK */
 
 	while (*s1 && *s2) {
 		if (*s1 != *s2) {
diff --git a/src/string/strcoll.c b/src/string/strcoll.c
index aab2f1f5..8ad9361e 100644
--- a/src/string/strcoll.c
+++ b/src/string/strcoll.c
@@ -13,6 +13,7 @@ int strcoll(const char *s1, const char *s2)
 	SIGNAL_SAFE(0);
 	ASSERT_NONNULL(s1);
 	ASSERT_NONNULL(s2);
+	/* no modification, overlap is OK */
 
 	x1 = malloc(strxfrm(x1, s1, 0));
 	x2 = malloc(strxfrm(x2, s2, 0));
diff --git a/src/string/strcspn.c b/src/string/strcspn.c
index 19f83fda..f2e8c588 100644
--- a/src/string/strcspn.c
+++ b/src/string/strcspn.c
@@ -10,6 +10,7 @@ size_t strcspn(const char *s1, const char *s2)
 	SIGNAL_SAFE(0);
 	ASSERT_NONNULL(s1);
 	ASSERT_NONNULL(s2);
+	/* no modification, overlap is OK */
 
 	for (i = 0; s1[i] != '\0'; i++) {
 		if (strchr (s2, s1[i]) != NULL) {
diff --git a/src/string/strncat_s.c b/src/string/strncat_s.c
index 700e8fb7..99b3f0ad 100644
--- a/src/string/strncat_s.c
+++ b/src/string/strncat_s.c
@@ -7,7 +7,7 @@ errno_t strncat_s(char * restrict s1, rsize_t s1max, const char * restrict s2, r
 	SIGNAL_SAFE(0);
 	ASSERT_NONNULL(s1);
 	ASSERT_NONNULL(s2);
-	(void)s1max; //ASSERT_NOOVERLAP(s1, s1max, s2, strlen(s1) + strlen(s2));
+	ASSERT_NOOVERLAP(s1, s1max, s2, n);
 
 	char *append = s1 + strlen(s1);
 	for (size_t i = 0; i < n; i++) {
diff --git a/src/string/strncmp.c b/src/string/strncmp.c
index bea831b3..627f9c47 100644
--- a/src/string/strncmp.c
+++ b/src/string/strncmp.c
@@ -8,6 +8,7 @@ int strncmp(const char *s1, const char *s2, size_t n)
 	SIGNAL_SAFE(0);
 	ASSERT_NONNULL(s1);
 	ASSERT_NONNULL(s2);
+	/* no modifcation, overlap is OK */
 
 	if (strlen(s1) < n) {
 		n = strlen(s1);
diff --git a/src/string/strpbrk.c b/src/string/strpbrk.c
index 714c282a..7225ac4c 100644
--- a/src/string/strpbrk.c
+++ b/src/string/strpbrk.c
@@ -10,6 +10,7 @@ char * strpbrk(const char *s1, const char *s2)
 	SIGNAL_SAFE(0);
 	ASSERT_NONNULL(s1);
 	ASSERT_NONNULL(s2);
+	/* no modifcation, overlap is OK */
 
 	for (i = 0; i < strlen (s1); i++) {
 		if (strchr(s2, s1[i]) != NULL) {
diff --git a/src/string/strspn.c b/src/string/strspn.c
index 156abe06..82e0dc9c 100644
--- a/src/string/strspn.c
+++ b/src/string/strspn.c
@@ -10,6 +10,7 @@ size_t strspn(const char *s1, const char *s2)
 	SIGNAL_SAFE(0);
 	ASSERT_NONNULL(s1);
 	ASSERT_NONNULL(s2);
+	/* no modification, overlap is OK */
 
 	for (i = 0; i < strlen (s1); i++) {
 		if (strchr(s2, s1[i]) == NULL) {
diff --git a/src/string/strstr.c b/src/string/strstr.c
index fa5db853..eac8ea77 100644
--- a/src/string/strstr.c
+++ b/src/string/strstr.c
@@ -12,6 +12,7 @@ char * strstr(const char *s1, const char *s2)
 	SIGNAL_SAFE(0);
 	ASSERT_NONNULL(s1);
 	ASSERT_NONNULL(s2);
+	/* no modifcation, overlap is OK */
 
 	l1 = strlen(s1);
 	l2 = strlen(s2);
diff --git a/src/string/strtok.c b/src/string/strtok.c
index 69b7fcc8..c46a9556 100644
--- a/src/string/strtok.c
+++ b/src/string/strtok.c
@@ -11,6 +11,7 @@ char * strtok(char * restrict s1, const char * restrict s2)
 	/* TODO */
 	SIGNAL_SAFE(0);
 	ASSERT_NONNULL(s2);
+	/* nothing is copied, overlap is OK */
 
 	/*
 	RETURN(CONSTANT(NULL), there are no further tokens, only token separators);
diff --git a/src/string/strtok_s.c b/src/string/strtok_s.c
index 859e4885..867029c6 100644
--- a/src/string/strtok_s.c
+++ b/src/string/strtok_s.c
@@ -4,6 +4,8 @@
 char * strtok_s(char * restrict s1, rsize_t * restrict s1max, const char * restrict s2, char **restrict ptr)
 {
 	SIGNAL_SAFE(0);
+	/* TODO: check for overlap */
+	/* what is the limit a pointer? */
 	(void)s1; (void)s1max; (void)s2; (void)ptr;
 	return NULL;
 }
diff --git a/src/string/strxfrm.c b/src/string/strxfrm.c
index fc16087a..9d0b5429 100644
--- a/src/string/strxfrm.c
+++ b/src/string/strxfrm.c
@@ -9,6 +9,7 @@ size_t strxfrm(char * restrict s1, const char * restrict s2, size_t n)
 	(void)s1; (void)s2; (void)n;
 	SIGNAL_SAFE(0);
 	ASSERT_NONNULL(s2);
+	ASSERT_NOOVERLAP(s1, n, s2, n);
 
 	if (n != 0) {
 		ASSERT_NONNULL(s1);