1 files changed, 89 insertions, 0 deletions
diff --git a/libc/test/src/stdio/fdopen_test.cpp b/libc/test/src/stdio/fdopen_test.cpp
new file mode 100644
index 000000000000..ef36cff2ffbd
--- /dev/null
+++ b/libc/test/src/stdio/fdopen_test.cpp
@@ -0,0 +1,89 @@
+//===-- Unittest for fdopen -----------------------------------------------===//
+//
+// 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/stdio/fdopen.h"
+
+#include "hdr/fcntl_macros.h"
+#include "src/errno/libc_errno.h"
+#include "src/fcntl/open.h"
+#include "src/stdio/fclose.h"
+#include "src/stdio/fgets.h"
+#include "src/stdio/fputs.h"
+#include "src/unistd/close.h"
+#include "test/UnitTest/ErrnoSetterMatcher.h"
+#include "test/UnitTest/Test.h"
+
+#include <sys/stat.h> // For S_IRWXU
+
+TEST(LlvmLibcStdioFdopenTest, WriteAppendRead) {
+  using LIBC_NAMESPACE::testing::ErrnoSetterMatcher::Succeeds;
+  LIBC_NAMESPACE::libc_errno = 0;
+  constexpr const char *TEST_FILE_NAME = "testdata/write_read_append.test";
+  auto TEST_FILE = libc_make_test_file_path(TEST_FILE_NAME);
+  int fd = LIBC_NAMESPACE::open(TEST_FILE, O_CREAT | O_TRUNC | O_RDWR, S_IRWXU);
+  auto *fp = LIBC_NAMESPACE::fdopen(fd, "w");
+  ASSERT_ERRNO_SUCCESS();
+  ASSERT_TRUE(nullptr != fp);
+  constexpr const char HELLO[] = "Hello";
+  LIBC_NAMESPACE::fputs(HELLO, fp);
+  LIBC_NAMESPACE::fclose(fp);
+  ASSERT_ERRNO_SUCCESS();
+
+  constexpr const char LLVM[] = "LLVM";
+  int fd2 = LIBC_NAMESPACE::open(TEST_FILE, O_CREAT | O_RDWR);
+  auto *fp2 = LIBC_NAMESPACE::fdopen(fd2, "a");
+  ASSERT_ERRNO_SUCCESS();
+  ASSERT_TRUE(nullptr != fp2);
+  LIBC_NAMESPACE::fputs(LLVM, fp2);
+  LIBC_NAMESPACE::fclose(fp2);
+  ASSERT_ERRNO_SUCCESS();
+
+  int fd3 = LIBC_NAMESPACE::open(TEST_FILE, O_CREAT | O_RDWR);
+  auto *fp3 = LIBC_NAMESPACE::fdopen(fd3, "r");
+  char buffer[10];
+  LIBC_NAMESPACE::fgets(buffer, sizeof(buffer), fp3);
+  ASSERT_STREQ("HelloLLVM", buffer);
+  LIBC_NAMESPACE::fclose(fp3);
+  ASSERT_ERRNO_SUCCESS();
+}
+
+TEST(LlvmLibcStdioFdopenTest, InvalidFd) {
+  LIBC_NAMESPACE::libc_errno = 0;
+  constexpr const char *TEST_FILE_NAME = "testdata/invalid_fd.test";
+  auto TEST_FILE = libc_make_test_file_path(TEST_FILE_NAME);
+  int fd = LIBC_NAMESPACE::open(TEST_FILE, O_CREAT | O_TRUNC);
+  LIBC_NAMESPACE::close(fd);
+  // With `fd` already closed, `fdopen` should fail and set the `errno` to EBADF
+  auto *fp = LIBC_NAMESPACE::fdopen(fd, "r");
+  ASSERT_ERRNO_EQ(EBADF);
+  ASSERT_TRUE(nullptr == fp);
+}
+
+TEST(LlvmLibcStdioFdopenTest, InvalidMode) {
+  LIBC_NAMESPACE::libc_errno = 0;
+  constexpr const char *TEST_FILE_NAME = "testdata/invalid_mode.test";
+  auto TEST_FILE = libc_make_test_file_path(TEST_FILE_NAME);
+  int fd = LIBC_NAMESPACE::open(TEST_FILE, O_CREAT | O_RDONLY, S_IRWXU);
+  ASSERT_ERRNO_SUCCESS();
+  ASSERT_GT(fd, 0);
+
+  // `Mode` must be one of "r", "w" or "a"
+  auto *fp = LIBC_NAMESPACE::fdopen(fd, "m+");
+  ASSERT_ERRNO_EQ(EINVAL);
+  ASSERT_TRUE(nullptr == fp);
+
+  // If the mode argument is invalid, then `fdopen` returns a nullptr and sets
+  // the `errno` to EINVAL. In this case the `mode` param can only be "r" or
+  // "r+"
+  auto *fp2 = LIBC_NAMESPACE::fdopen(fd, "w");
+  ASSERT_ERRNO_EQ(EINVAL);
+  ASSERT_TRUE(nullptr == fp2);
+  LIBC_NAMESPACE::libc_errno = 0;
+  LIBC_NAMESPACE::close(fd);
+  ASSERT_ERRNO_SUCCESS();
+}