[libc] Add the implementation of the fdopen function

Author: simonzgx

libc/config/linux/aarch64/entrypoints.txt

@@ -201,6 +201,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.stdio.snprintf
     libc.src.stdio.vsprintf
     libc.src.stdio.vsnprintf
+    libc.src.stdio.fdopen
     #libc.src.stdio.sscanf
     #libc.src.stdio.scanf
     #libc.src.stdio.fscanf

libc/config/linux/riscv/entrypoints.txt

@@ -209,6 +209,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.stdio.sscanf
     libc.src.stdio.scanf
     libc.src.stdio.fscanf
+    libc.src.stdio.fdopen
 
     # sys/mman.h entrypoints
     libc.src.sys.mman.madvise

libc/config/linux/x86_64/entrypoints.txt

@@ -215,6 +215,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.stdio.scanf
     libc.src.stdio.fscanf
     libc.src.stdio.fileno
+    libc.src.stdio.fdopen
 
     # sys/epoll.h entrypoints
     libc.src.sys.epoll.epoll_create

libc/spec/posix.td

@@ -1293,6 +1293,11 @@ def POSIX : StandardSpec<"POSIX"> {
             RetValSpec<IntType>,
             [ArgSpec<FILEPtr>]
           >,
+          FunctionSpec<
+            "fdopen",
+            RetValSpec<FILEPtr>,
+            [ArgSpec<IntType>, ArgSpec<ConstCharPtr>]
+          >,
       ]
   >;
 

libc/src/fcntl/linux/fcntl.cpp

@@ -29,8 +29,6 @@ LLVM_LIBC_FUNCTION(int, fcntl, (int fd, int cmd, ...)) {
   va_end(varargs);
 
   switch (cmd) {
-  case F_SETLKW:
-    return syscall_impl<int>(SYS_fcntl, fd, cmd, arg);
   case F_OFD_SETLKW: {
     struct flock *flk = reinterpret_cast<struct flock *>(arg);
     // convert the struct to a flock64
@@ -86,8 +84,15 @@ LLVM_LIBC_FUNCTION(int, fcntl, (int fd, int cmd, ...)) {
     return -1;
   }
   // The general case
-  default:
-    return syscall_impl<int>(SYS_fcntl, fd, cmd, reinterpret_cast<void *>(arg));
+  default: {
+    int retVal =
+        syscall_impl<int>(SYS_fcntl, fd, cmd, reinterpret_cast<void *>(arg));
+    if (retVal >= 0) {
+      return retVal;
+    }
+    libc_errno = -retVal;
+    return -1;
+  }
   }
 }
 } // namespace LIBC_NAMESPACE

libc/src/stdio/CMakeLists.txt

@@ -263,6 +263,13 @@ add_entrypoint_object(
     .${LIBC_TARGET_OS}.rename
 )
 
+add_entrypoint_object(
+  fdopen
+  ALIAS
+  DEPENDS
+    .${LIBC_TARGET_OS}.fdopen
+)
+
 # These entrypoints have multiple potential implementations.
 add_stdio_entrypoint_object(feof)
 add_stdio_entrypoint_object(feof_unlocked)

libc/src/stdio/fdopen.h

@@ -0,0 +1,20 @@
+//===-- Implementation header of open ---------------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_STDIO_FDOPEN_H
+#define LLVM_LIBC_SRC_STDIO_FDOPEN_H
+
+#include <stdio.h>
+
+namespace LIBC_NAMESPACE {
+
+FILE *fdopen(int fd, const char *mode);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDIO_FDOPEN_H

libc/src/stdio/linux/CMakeLists.txt

@@ -24,3 +24,18 @@ add_entrypoint_object(
     libc.src.__support.OSUtil.osutil
     libc.src.errno.errno
 )
+
+add_entrypoint_object(
+  fdopen
+  SRCS
+    fdopen.cpp
+  HDRS
+    ../fdopen.h
+  DEPENDS
+    libc.include.fcntl
+    libc.include.stdio
+    libc.src.errno.errno
+    libc.src.fcntl.fcntl
+    libc.src.stdio.fseek
+    libc.src.__support.File.linux.file
+)

libc/src/stdio/linux/fdopen.cpp

@@ -0,0 +1,79 @@
+//===-- Implementation of fprintf -------------------------------*- C++ -*-===//
+//
+// 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 "include/llvm-libc-macros/generic-error-number-macros.h"
+#include "include/llvm-libc-macros/linux/fcntl-macros.h"
+#include "src/__support/File/linux/file.h"
+#include "src/errno/libc_errno.h"
+#include "src/fcntl/fcntl.h"
+#include "src/stdio/fseek.h"
+
+#include <stdio.h>
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(::FILE *, fdopen, (int fd, const char *mode)) {
+  using ModeFlags = File::ModeFlags;
+  ModeFlags modeflags = File::mode_flags(mode);
+  if (modeflags == 0) {
+    libc_errno = EINVAL;
+    return nullptr;
+  }
+
+  int fd_flags = LIBC_NAMESPACE::fcntl(fd, F_GETFL);
+  if (fd_flags == -1) {
+    return nullptr;
+  }
+
+  using OpenMode = File::OpenMode;
+  if (((fd_flags & O_ACCMODE) == O_RDONLY &&
+       !(modeflags & static_cast<ModeFlags>(OpenMode::READ))) ||
+      ((fd_flags & O_ACCMODE) == O_WRONLY &&
+       !(modeflags & static_cast<ModeFlags>(OpenMode::WRITE)))) {
+    libc_errno = EINVAL;
+    return nullptr;
+  }
+
+  bool do_seek = false;
+  if ((modeflags & static_cast<ModeFlags>(OpenMode::APPEND)) &&
+      !(fd_flags & O_APPEND)) {
+    do_seek = true;
+    if (LIBC_NAMESPACE::fcntl(fd, F_SETFL, fd_flags | O_APPEND) == -1) {
+      libc_errno = EBADF;
+      return nullptr;
+    }
+  }
+
+  uint8_t *buffer;
+  {
+    AllocChecker ac;
+    buffer = new (ac) uint8_t[File::DEFAULT_BUFFER_SIZE];
+    if (!ac) {
+      libc_errno = ENOMEM;
+      return nullptr;
+    }
+  }
+  AllocChecker ac;
+  auto *linux_file = new (ac)
+      LinuxFile(fd, buffer, File::DEFAULT_BUFFER_SIZE, _IOFBF, true, modeflags);
+  if (!ac) {
+    libc_errno = ENOMEM;
+    return nullptr;
+  }
+  auto *file = reinterpret_cast<::FILE *>(linux_file);
+  if (do_seek && LIBC_NAMESPACE::fseek(file, 0, SEEK_END) != 0) {
+    free(linux_file);
+    return nullptr;
+  }
+
+  return file;
+}
+
+} // namespace LIBC_NAMESPACE

libc/test/src/fcntl/fcntl_test.cpp

@@ -153,3 +153,13 @@ TEST(LlvmLibcFcntlTest, FcntlGetLkWrite) {
 
   ASSERT_THAT(LIBC_NAMESPACE::close(fd), Succeeds(0));
 }
+
+TEST(LlvmLibcFcntlTest, UseAfterClose) {
+  using LIBC_NAMESPACE::testing::ErrnoSetterMatcher::Succeeds;
+  constexpr const char *TEST_FILE_NAME = "testdata/fcntl_use_after_close.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);
+  ASSERT_THAT(LIBC_NAMESPACE::close(fd), Succeeds(0));
+  ASSERT_EQ(-1, LIBC_NAMESPACE::fcntl(fd, F_GETFL));
+  ASSERT_ERRNO_EQ(EBADF);
+}

libc/test/src/stdio/CMakeLists.txt

@@ -369,6 +369,20 @@ if(${LIBC_TARGET_OS} STREQUAL "linux")
       libc.src.unistd.close
       libc.test.UnitTest.ErrnoSetterMatcher
   )
+
+  add_libc_test(
+    fdopen_test
+    SUITE
+      libc_stdio_unittests
+    SRCS
+      fdopen_test.cpp
+    DEPENDS
+      libc.src.fcntl.open
+      libc.src.stdio.fclose
+      libc.src.stdio.fdopen
+      libc.src.unistd.close
+      libc.test.UnitTest.ErrnoSetterMatcher
+  )
 endif()
 
 add_libc_test(

libc/test/src/stdio/fdopen_test.cpp

@@ -0,0 +1,68 @@
+//===-- Unittest for fcntl ------------------------------------------------===//
+//
+// 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 "include/llvm-libc-macros/linux/fcntl-macros.h"
+#include "src/stdio/fdopen.h"
+
+#include "src/errno/libc_errno.h"
+#include "src/fcntl/fcntl.h"
+#include "src/fcntl/open.h"
+#include "src/stdio/fclose.h"
+#include "src/unistd/close.h"
+#include "test/UnitTest/ErrnoSetterMatcher.h"
+#include "test/UnitTest/LibcTest.h"
+#include "test/UnitTest/Test.h"
+
+#include <sys/stat.h> // For S_IRWXU
+
+TEST(LlvmLibcStdioFdopenTest, InvalidInput) {
+  using LIBC_NAMESPACE::testing::ErrnoSetterMatcher::Succeeds;
+  LIBC_NAMESPACE::libc_errno = 0;
+  constexpr const char *TEST_FILE_NAME = "testdata/fdopen_invalid_inputs.test";
+  auto TEST_FILE = libc_make_test_file_path(TEST_FILE_NAME);
+  int fd = LIBC_NAMESPACE::open(TEST_FILE, O_CREAT | O_TRUNC | O_RDONLY);
+  auto *fp = LIBC_NAMESPACE::fdopen(fd, "m+");
+  ASSERT_ERRNO_EQ(EINVAL);
+  ASSERT_TRUE(nullptr == fp);
+  LIBC_NAMESPACE::close(fd);
+  LIBC_NAMESPACE::libc_errno = 0;
+  fp = LIBC_NAMESPACE::fdopen(fd, "r");
+  ASSERT_ERRNO_EQ(EBADF);
+  ASSERT_TRUE(nullptr == fp);
+}
+
+TEST(LlvmLibcStdioFdopenTest, InvalidMode) {
+  using LIBC_NAMESPACE::testing::ErrnoSetterMatcher::Succeeds;
+  LIBC_NAMESPACE::libc_errno = 0;
+  constexpr const char *TEST_FILE_NAME = "testdata/fdopen_invid_mode.test";
+  auto TEST_FILE = libc_make_test_file_path(TEST_FILE_NAME);
+  int fd = LIBC_NAMESPACE::open(TEST_FILE, O_CREAT | O_TRUNC | O_RDONLY);
+  ASSERT_ERRNO_SUCCESS();
+  ASSERT_GT(fd, 0);
+  auto *fp = LIBC_NAMESPACE::fdopen(fd, "r+");
+  ASSERT_ERRNO_SUCCESS();
+  ASSERT_TRUE(nullptr != fp);
+  ASSERT_THAT(LIBC_NAMESPACE::fclose(fp), Succeeds(0));
+  // 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+"
+  int fd2 = LIBC_NAMESPACE::open(TEST_FILE, O_CREAT | O_TRUNC | O_RDONLY);
+  ASSERT_ERRNO_SUCCESS();
+  ASSERT_GT(fd2, 0);
+  auto *fp2 = LIBC_NAMESPACE::fdopen(fd2, "w");
+  ASSERT_ERRNO_EQ(EINVAL);
+  ASSERT_TRUE(nullptr == fp2);
+}
+
+TEST(LlvmLibcStdioFdopenTest, WriteRead) {
+
+}
+
+TEST(LlvmLibcStdioFdopenTest, Append) {}
+
+TEST(LlvmLibcStdioFdopenTest, AppendPlus) {}