[libc] Add strlcat

Differential Revision: https://reviews.llvm.org/D125978

2 files changed, 47 insertions, 0 deletions

diff --git a/libc/test/src/string/CMakeLists.txt b/libc/test/src/string/CMakeLists.txt
index 5bdb47a7e672..e60f9ab3d399 100644
--- a/libc/test/src/string/CMakeLists.txt
+++ b/libc/test/src/string/CMakeLists.txt
@@ -124,6 +124,16 @@ add_libc_unittest(
 )
 
 add_libc_unittest(
+  strlcat_test
+  SUITE
+    libc_string_unittests
+  SRCS
+    strlcat_test.cpp
+  DEPENDS
+    libc.src.string.strlcat
+)
+
+add_libc_unittest(
   strlcpy_test
   SUITE
     libc_string_unittests
diff --git a/libc/test/src/string/strlcat_test.cpp b/libc/test/src/string/strlcat_test.cpp
new file mode 100644
index 000000000000..66db15e58927
--- /dev/null
+++ b/libc/test/src/string/strlcat_test.cpp
@@ -0,0 +1,37 @@
+//===-- Unittests for strlcat ---------------------------------------------===//
+//
+// 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/strlcat.h"
+#include "utils/UnitTest/Test.h"
+#include <stdlib.h>
+
+TEST(LlvmLibcStrlcatTest, TooBig) {
+  const char *str = "cd";
+  char buf[4]{"ab"};
+  EXPECT_EQ(__llvm_libc::strlcat(buf, str, 3), size_t(4));
+  EXPECT_STREQ(buf, "ab");
+  EXPECT_EQ(__llvm_libc::strlcat(buf, str, 4), size_t(4));
+  EXPECT_STREQ(buf, "abc");
+}
+
+TEST(LlvmLibcStrlcatTest, Smaller) {
+  const char *str = "cd";
+  char buf[7]{"ab"};
+
+  EXPECT_EQ(__llvm_libc::strlcat(buf, str, 7), size_t(4));
+  EXPECT_STREQ(buf, "abcd");
+}
+
+TEST(LlvmLibcStrlcatTest, No0) {
+  const char *str = "cd";
+  char buf[7]{"ab"};
+  EXPECT_EQ(__llvm_libc::strlcat(buf, str, 1), size_t(3));
+  EXPECT_STREQ(buf, "ab");
+  EXPECT_EQ(__llvm_libc::strlcat(buf, str, 2), size_t(4));
+  EXPECT_STREQ(buf, "ab");
+}