LibC: Implement wcsstr

Tests/LibC/TestWchar.cpp

@@ -35,6 +35,36 @@ TEST_CASE(wcspbrk)
  EXPECT_EQ(ret, input + 2);
 }
 
+TEST_CASE(wcsstr)
+{
+ const wchar_t* input = L"abcde";
+ wchar_t* ret;
+
+ // Empty needle should return haystack.
+ ret = wcsstr(input, L"");
+ EXPECT_EQ(ret, input);
+
+ // Test exact match.
+ ret = wcsstr(input, input);
+ EXPECT_EQ(ret, input);
+
+ // Test match at string start.
+ ret = wcsstr(input, L"ab");
+ EXPECT_EQ(ret, input);
+
+ // Test match at string end.
+ ret = wcsstr(input, L"de");
+ EXPECT_EQ(ret, input + 3);
+
+ // Test no match.
+ ret = wcsstr(input, L"z");
+ EXPECT_EQ(ret, nullptr);
+
+ // Test needle that is longer than the haystack.
+ ret = wcsstr(input, L"abcdef");
+ EXPECT_EQ(ret, nullptr);
+}
+
 TEST_CASE(wcscoll)
 {
  // Check if wcscoll is sorting correctly. At the moment we are doing raw char comparisons,

Userland/Libraries/LibC/wchar.cpp

@@ -355,4 +355,24 @@ wchar_t* wcspbrk(const wchar_t* wcs, const wchar_t* accept)
 
  return nullptr;
 }
+
+wchar_t* wcsstr(const wchar_t* haystack, const wchar_t* needle)
+{
+ size_t nlen = wcslen(needle);
+
+ if (nlen == 0)
+ return const_cast<wchar_t*>(haystack);
+
+ size_t hlen = wcslen(haystack);
+
+ while (hlen >= nlen) {
+ if (wcsncmp(haystack, needle, nlen) == 0)
+ return const_cast<wchar_t*>(haystack);
+
+ haystack++;
+ hlen--;
+ }
+
+ return nullptr;
+}
 }

Userland/Libraries/LibC/wchar.h

@@ -42,5 +42,6 @@ int wcscoll(const wchar_t*, const wchar_t*);
 int wctob(wint_t);
 int mbsinit(const mbstate_t*);
 wchar_t* wcspbrk(const wchar_t*, const wchar_t*);
+wchar_t* wcsstr(const wchar_t*, const wchar_t*);
 
 __END_DECLS