[libc] Implement str{,n}casecmp

Differential Revision: https://reviews.llvm.org/D141236

1 files changed, 26 insertions, 0 deletions

diff --git a/libc/src/string/strncasecmp.cpp b/libc/src/string/strncasecmp.cpp
new file mode 100644
index 000000000000..0fb2f81b17fe
--- /dev/null
+++ b/libc/src/string/strncasecmp.cpp
@@ -0,0 +1,26 @@
+//===-- Implementation of strncasecmp -------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/string/strncasecmp.h"
+
+#include "src/__support/common.h"
+#include "src/__support/ctype_utils.h"
+#include "src/string/memory_utils/strcmp_implementations.h"
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, strncasecmp,
+                   (const char *left, const char *right, size_t n)) {
+  auto case_cmp = [](char a, char b) {
+    return __llvm_libc::internal::tolower(a) -
+           __llvm_libc::internal::tolower(b);
+  };
+  return strncmp_implementation(left, right, n, case_cmp);
+}
+
+} // namespace __llvm_libc