From 3db9e4ee0577f4184554942a1482e43e4c8e924f Mon Sep 17 00:00:00 2001
From: David <David.Samir.WD@gmail.com>
Date: Thu, 22 Oct 2026 14:57:02 +0100
Subject: [PATCH] test(libc): cover the standard string exports

guest_strings checked the bounds-checked and BSD string functions but not
the plain C ones. It now checks strcmp, strncmp and strcoll by sign,
strlen, strcpy and strcat return values, strncpy zero padding and its
unterminated truncation, strstr with an empty needle, strspn, bcmp and
bzero.
---
 core/libs/tests/GuestStrings.cpp | 49 ++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/core/libs/tests/GuestStrings.cpp b/core/libs/tests/GuestStrings.cpp
index ef2f2f0a69..34eeb0aa03 100644
--- a/core/libs/tests/GuestStrings.cpp
+++ b/core/libs/tests/GuestStrings.cpp
@@ -8,6 +8,20 @@
 #include <cstdlib>
 #include <string>
 
+extern "C" {
+void APS5_VABI bzero_nid_postfix(void* destination, size_t count);
+int APS5_VABI bcmp_nid_postfix(const void* s1, const void* s2, size_t n);
+int APS5_VABI strcmp_nid_postfix(const char* s1, const char* s2);
+int APS5_VABI strncmp_nid_postfix(const char* s1, const char* s2, size_t n);
+int APS5_VABI strcoll_nid_postfix(const char* s1, const char* s2);
+size_t APS5_VABI strlen_nid_postfix(const char* s);
+char* APS5_VABI strcpy_nid_postfix(char* dest, const char* src);
+char* APS5_VABI strncpy_nid_postfix(char* dest, const char* src, size_t count);
+char* APS5_VABI strcat_nid_postfix(char* dest, const char* src);
+char* APS5_VABI strstr_nid_postfix(const char* haystack, const char* needle);
+size_t APS5_VABI strspn_nid_postfix(const char* s, const char* accept);
+}
+
 extern "C" {
 void APS5_VABI bcopy_nid_postfix(const void*, void*, std::size_t);
 char* APS5_VABI basename_nid_postfix(const char*);
@@ -82,6 +96,40 @@ static bool CheckMemcpyOverlap() {
     return correct;
 }
 
+static int Sign(int value) {
+    return value < 0 ? -1 : value > 0 ? 1 : 0;
+}
+
+static void CheckStandardStrings() {
+    Require(strcmp_nid_postfix("abc", "abc") == 0 && Sign(strcmp_nid_postfix("abc", "abd")) == -1 && Sign(strcmp_nid_postfix("abc", "ab")) == 1);
+    Require(Sign(strcmp_nid_postfix("\x80", "\x7f")) == 1);
+    Require(strncmp_nid_postfix("abcX", "abcY", 3) == 0 && Sign(strncmp_nid_postfix("abcX", "abcY", 4)) == -1 && strncmp_nid_postfix("a", "b", 0) == 0);
+    Require(strcoll_nid_postfix("same", "same") == 0 && Sign(strcoll_nid_postfix("B", "a")) == -1);
+    Require(strlen_nid_postfix("") == 0 && strlen_nid_postfix("seven 7") == 7);
+
+    char buffer[16];
+    std::memset(buffer, 'x', sizeof(buffer));
+    Require(strcpy_nid_postfix(buffer, "ab") == buffer && std::memcmp(buffer, "ab\0x", 4) == 0);
+    Require(strcat_nid_postfix(buffer, "cd") == buffer && std::strcmp(buffer, "abcd") == 0);
+
+    std::memset(buffer, 'x', sizeof(buffer));
+    Require(strncpy_nid_postfix(buffer, "ab", 5) == buffer && std::memcmp(buffer, "ab\0\0\0x", 6) == 0);
+    std::memset(buffer, 'x', sizeof(buffer));
+    Require(strncpy_nid_postfix(buffer, "abcdef", 3) == buffer && std::memcmp(buffer, "abcx", 4) == 0);
+
+    const char* text = "needle in a haystack";
+    Require(strstr_nid_postfix(text, "hay") == text + 12 && strstr_nid_postfix(text, "") == text && strstr_nid_postfix(text, "hey") == nullptr);
+    Require(strspn_nid_postfix("aabbc", "ab") == 4 && strspn_nid_postfix("xyz", "ab") == 0 && strspn_nid_postfix("ab", "") == 0);
+
+    unsigned char bytes[6] = {1, 2, 3, 4, 5, 6};
+    const unsigned char same[6] = {1, 2, 3, 4, 5, 6};
+    Require(bcmp_nid_postfix(bytes, same, 6) == 0 && bcmp_nid_postfix(bytes, "zz", 0) == 0);
+    bytes[5] = 9;
+    Require(bcmp_nid_postfix(bytes, same, 6) != 0 && bcmp_nid_postfix(bytes, same, 5) == 0);
+    bzero_nid_postfix(bytes + 1, 4);
+    Require(bytes[0] == 1 && bytes[1] == 0 && bytes[4] == 0 && bytes[5] == 9);
+}
+
 static void CheckSecureCopySizeLimits() {
     using Copy = int (APS5_VABI*)(void*, std::size_t, const void*, std::size_t);
     constexpr std::size_t RsizeMax = SIZE_MAX >> 1;
@@ -327,6 +375,7 @@ static void CheckCharacterConversionInSearches() {
 }
 
 int main() {
+    CheckStandardStrings();
     CheckStrtonum();
     CheckBcopy();
     if (!CheckDirnameLengths()) return 1;