[libc] Add POSIX functions dup, dup2, and GNU extension function dup3.

Reviewed By: lntue

Differential Revision: https://reviews.llvm.org/D133748

libc/config/linux/aarch64/entrypoints.txt

@@ -113,6 +113,9 @@ set(TARGET_LIBC_ENTRYPOINTS
     # unistd.h entrypoints
     libc.src.unistd.chdir
     libc.src.unistd.close
+    libc.src.unistd.dup
+    libc.src.unistd.dup2
+    libc.src.unistd.dup3
     libc.src.unistd.fchdir
     libc.src.unistd.fsync
     libc.src.unistd.ftruncate

libc/config/linux/x86_64/entrypoints.txt

@@ -113,6 +113,9 @@ set(TARGET_LIBC_ENTRYPOINTS
     # unistd.h entrypoints
     libc.src.unistd.chdir
     libc.src.unistd.close
+    libc.src.unistd.dup
+    libc.src.unistd.dup2
+    libc.src.unistd.dup3
     libc.src.unistd.fchdir
     libc.src.unistd.fsync
     libc.src.unistd.ftruncate

libc/include/llvm-libc-macros/linux/fcntl-macros.h

@@ -70,4 +70,11 @@
 // has to perform the equivalent of "rmdir" on the path argument.
 #define AT_REMOVEDIR 0x200
 
+// Values of SYS_fcntl commands.
+#define F_DUPFD 0
+#define F_GETFD 1
+#define F_SETFD 2
+#define F_GETFL 3
+#define F_SETFL 4
+
 #endif // __LLVM_LIBC_MACROS_LINUX_FCNTL_MACROS_H

libc/spec/gnu_ext.td

@@ -144,6 +144,20 @@ def GnuExtensions : StandardSpec<"GNUExtensions"> {
       ]
   >;
 
+  HeaderSpec UniStd = HeaderSpec<
+    "unistd.h",
+    [], // Macros
+    [], // Types
+    [], // Enumerations
+    [
+        FunctionSpec<
+            "dup2",
+            RetValSpec<IntType>,
+            [ArgSpec<IntType>, ArgSpec<IntType>, ArgSpec<IntType>]
+        >,
+    ]
+  >;
+
   let Headers = [
     CType,
     FEnv,
@@ -152,5 +166,6 @@ def GnuExtensions : StandardSpec<"GNUExtensions"> {
     SendFile,
     StdIO,
     String,
+    UniStd,
   ];
 }

libc/spec/posix.td

@@ -266,6 +266,21 @@ def POSIX : StandardSpec<"POSIX"> {
           RetValSpec<IntType>,
           [ArgSpec<ConstCharPtr>]
         >,
+        FunctionSpec<
+          "dup",
+          RetValSpec<IntType>,
+          [ArgSpec<IntType>]
+        >,
+        FunctionSpec<
+          "dup2",
+          RetValSpec<IntType>,
+          [ArgSpec<IntType>, ArgSpec<IntType>]
+        >,
+        FunctionSpec<
+          "dup3",
+          RetValSpec<IntType>,
+          [ArgSpec<IntType>, ArgSpec<IntType>, ArgSpec<IntType>]
+        >,
         FunctionSpec<
           "fchdir",
           RetValSpec<IntType>,

libc/src/unistd/CMakeLists.txt

@@ -16,6 +16,27 @@ add_entrypoint_object(
     .${LIBC_TARGET_OS}.close
 )
 
+add_entrypoint_object(
+  dup
+  ALIAS
+  DEPENDS
+    .${LIBC_TARGET_OS}.dup
+)
+
+add_entrypoint_object(
+  dup2
+  ALIAS
+  DEPENDS
+    .${LIBC_TARGET_OS}.dup2
+)
+
+add_entrypoint_object(
+  dup3
+  ALIAS
+  DEPENDS
+    .${LIBC_TARGET_OS}.dup3
+)
+
 add_entrypoint_object(
   fchdir
   ALIAS

libc/src/unistd/dup.h

@@ -0,0 +1,20 @@
+//===-- Implementation header for dup ---------------------------*- 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_UNISTD_DUP_H
+#define LLVM_LIBC_SRC_UNISTD_DUP_H
+
+#include <unistd.h>
+
+namespace __llvm_libc {
+
+int dup(int fd);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_UNISTD_DUP_H

libc/src/unistd/dup2.h

@@ -0,0 +1,20 @@
+//===-- Implementation header for dup2 --------------------------*- 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_UNISTD_DUP2_H
+#define LLVM_LIBC_SRC_UNISTD_DUP2_H
+
+#include <unistd.h>
+
+namespace __llvm_libc {
+
+int dup2(int oldfd, int newfd);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_UNISTD_DUP2_H

libc/src/unistd/dup3.h

@@ -0,0 +1,20 @@
+//===-- Implementation header for dup3 --------------------------*- 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_UNISTD_DUP3_H
+#define LLVM_LIBC_SRC_UNISTD_DUP3_H
+
+#include <unistd.h>
+
+namespace __llvm_libc {
+
+int dup3(int oldfd, int newfd, int flags);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_UNISTD_DUP3_H

libc/src/unistd/linux/CMakeLists.txt

@@ -24,6 +24,46 @@ add_entrypoint_object(
     libc.src.errno.errno
 )
 
+add_entrypoint_object(
+  dup
+  SRCS
+    dup.cpp
+  HDRS
+    ../dup.h
+  DEPENDS
+    libc.include.unistd
+    libc.include.sys_syscall
+    libc.src.__support.OSUtil.osutil
+    libc.src.errno.errno
+)
+
+add_entrypoint_object(
+  dup2
+  SRCS
+    dup2.cpp
+  HDRS
+    ../dup2.h
+  DEPENDS
+    libc.include.fcntl
+    libc.include.unistd
+    libc.include.sys_syscall
+    libc.src.__support.OSUtil.osutil
+    libc.src.errno.errno
+)
+
+add_entrypoint_object(
+  dup3
+  SRCS
+    dup3.cpp
+  HDRS
+    ../dup3.h
+  DEPENDS
+    libc.include.unistd
+    libc.include.sys_syscall
+    libc.src.__support.OSUtil.osutil
+    libc.src.errno.errno
+)
+
 add_entrypoint_object(
   fchdir
   SRCS

libc/src/unistd/linux/dup.cpp

@@ -0,0 +1,28 @@
+//===-- Linux implementation of dup ---------------------------------------===//
+//
+// 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/unistd/dup.h"
+
+#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "src/__support/common.h"
+
+#include <errno.h>
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, dup, (int fd)) {
+  long ret = __llvm_libc::syscall(SYS_dup, fd);
+  if (ret < 0) {
+    errno = -ret;
+    return -1;
+  }
+  return ret;
+}
+
+} // namespace __llvm_libc

libc/src/unistd/linux/dup2.cpp

@@ -0,0 +1,47 @@
+//===-- Linux implementation of dup2 --------------------------------------===//
+//
+// 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/unistd/dup2.h"
+
+#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "src/__support/common.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, dup2, (int oldfd, int newfd)) {
+#ifdef SYS_dup2
+  // If dup2 syscall is available, we make use of directly.
+  long ret = __llvm_libc::syscall(SYS_dup2, oldfd, newfd);
+#elif defined(SYS_dup3)
+  // If dup2 syscall is not available, we try using the dup3 syscall. However,
+  // dup3 fails if oldfd is the same as newfd. So, we handle that case
+  // separately before making the dup3 syscall.
+  if (oldfd == newfd) {
+    // Check if oldfd is actually a valid file descriptor.
+    long ret = __llvm_libc::syscall(SYS_fcntl, oldfd, F_GETFD);
+    if (ret >= 0)
+      return oldfd;
+    errno = -ret;
+    return -1;
+  }
+  long ret = __llvm_libc::syscall(SYS_dup3, oldfd, newfd, 0);
+#else
+#error "SYS_dup2 and SYS_dup3 not available for the target."
+#endif
+  if (ret < 0) {
+    errno = -ret;
+    return -1;
+  }
+  return ret;
+}
+
+} // namespace __llvm_libc

libc/src/unistd/linux/dup3.cpp

@@ -0,0 +1,28 @@
+//===-- Linux implementation of dup3 --------------------------------------===//
+//
+// 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/unistd/dup3.h"
+
+#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "src/__support/common.h"
+
+#include <errno.h>
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, dup3, (int oldfd, int newfd, int flags)) {
+  // If dup2 syscall is available, we make use of directly.
+  long ret = __llvm_libc::syscall(SYS_dup3, oldfd, newfd, flags);
+  if (ret >= 0)
+    return ret;
+  errno = -ret;
+  return -1;
+}
+
+} // namespace __llvm_libc

libc/test/src/unistd/CMakeLists.txt

@@ -17,6 +17,60 @@ add_libc_unittest(
     libc.test.errno_setter_matcher
 )
 
+add_libc_unittest(
+  dup_test
+  SUITE
+    libc_unistd_unittests
+  SRCS
+    dup_test.cpp
+  DEPENDS
+    libc.include.errno
+    libc.include.unistd
+    libc.src.fcntl.open
+    libc.src.unistd.close
+    libc.src.unistd.dup
+    libc.src.unistd.read
+    libc.src.unistd.unlink
+    libc.src.unistd.write
+    libc.test.errno_setter_matcher
+)
+
+add_libc_unittest(
+  dup2_test
+  SUITE
+    libc_unistd_unittests
+  SRCS
+    dup2_test.cpp
+  DEPENDS
+    libc.include.errno
+    libc.include.unistd
+    libc.src.fcntl.open
+    libc.src.unistd.close
+    libc.src.unistd.dup2
+    libc.src.unistd.read
+    libc.src.unistd.unlink
+    libc.src.unistd.write
+    libc.test.errno_setter_matcher
+)
+
+add_libc_unittest(
+  dup3_test
+  SUITE
+    libc_unistd_unittests
+  SRCS
+    dup3_test.cpp
+  DEPENDS
+    libc.include.errno
+    libc.include.unistd
+    libc.src.fcntl.open
+    libc.src.unistd.close
+    libc.src.unistd.dup3
+    libc.src.unistd.read
+    libc.src.unistd.unlink
+    libc.src.unistd.write
+    libc.test.errno_setter_matcher
+)
+
 add_libc_unittest(
   fchdir_test
   SUITE

libc/test/src/unistd/dup2_test.cpp

@@ -0,0 +1,63 @@
+//===-- Unittests for dup -------------------------------------------------===//
+//
+// 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/fcntl/open.h"
+#include "src/unistd/close.h"
+#include "src/unistd/dup2.h"
+#include "src/unistd/read.h"
+#include "src/unistd/unlink.h"
+#include "src/unistd/write.h"
+#include "test/ErrnoSetterMatcher.h"
+#include "utils/UnitTest/Test.h"
+#include "utils/testutils/FDReader.h"
+
+#include <errno.h>
+
+TEST(LlvmLibcdupTest, ReadAndWriteViaDup) {
+  constexpr int DUPFD = 0xD0;
+  errno = 0;
+  using __llvm_libc::testing::ErrnoSetterMatcher::Succeeds;
+  constexpr const char *TEST_FILE = "testdata/dup.test";
+  int fd = __llvm_libc::open(TEST_FILE, O_WRONLY | O_CREAT, S_IRWXU);
+  ASSERT_EQ(errno, 0);
+  ASSERT_GT(fd, 0);
+  int dupfd = __llvm_libc::dup2(fd, DUPFD);
+  ASSERT_EQ(errno, 0);
+  ASSERT_EQ(dupfd, DUPFD);
+
+  // Write something via the dup
+  constexpr char WRITE_DATA[] = "Hello, dup!";
+  constexpr size_t WRITE_SIZE = sizeof(WRITE_DATA);
+  ASSERT_EQ(ssize_t(WRITE_SIZE),
+            __llvm_libc::write(dupfd, WRITE_DATA, WRITE_SIZE));
+  ASSERT_THAT(__llvm_libc::close(dupfd), Succeeds(0));
+
+  // Reopen the file for reading and create a dup.
+  fd = __llvm_libc::open(TEST_FILE, O_RDONLY);
+  ASSERT_EQ(errno, 0);
+  ASSERT_GT(fd, 0);
+  dupfd = __llvm_libc::dup2(fd, DUPFD);
+  ASSERT_EQ(errno, 0);
+  ASSERT_EQ(dupfd, DUPFD);
+
+  // Read the file content via the dup.
+  char buf[WRITE_SIZE];
+  ASSERT_THAT(__llvm_libc::read(dupfd, buf, WRITE_SIZE), Succeeds(WRITE_SIZE));
+  ASSERT_STREQ(buf, WRITE_DATA);
+
+  // Verify that duping to the same fd value succeeds.
+  ASSERT_THAT(__llvm_libc::dup2(dupfd, dupfd), Succeeds(dupfd));
+
+  ASSERT_THAT(__llvm_libc::close(dupfd), Succeeds(0));
+  ASSERT_THAT(__llvm_libc::unlink(TEST_FILE), Succeeds(0));
+}
+
+TEST(LlvmLibcdupTest, DupBadFD) {
+  using __llvm_libc::testing::ErrnoSetterMatcher::Fails;
+  ASSERT_THAT(__llvm_libc::dup2(-1, 123), Fails(EBADF));
+}

libc/test/src/unistd/dup3_test.cpp

@@ -0,0 +1,69 @@
+//===-- Unittests for dup3 ------------------------------------------------===//
+//
+// 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/fcntl/open.h"
+#include "src/unistd/close.h"
+#include "src/unistd/dup3.h"
+#include "src/unistd/read.h"
+#include "src/unistd/unlink.h"
+#include "src/unistd/write.h"
+#include "test/ErrnoSetterMatcher.h"
+#include "utils/UnitTest/Test.h"
+#include "utils/testutils/FDReader.h"
+
+#include <errno.h>
+
+// The tests here are exactly the same as those of dup2. We only test the
+// plumbing of the dup3 syscall and not the dup3 functionality itself as it is
+// a simple syscall wrapper. Testing dup3 functionality is beyond the scope of
+// this test.
+
+TEST(LlvmLibcdupTest, ReadAndWriteViaDup) {
+  constexpr int DUPFD = 0xD0;
+  errno = 0;
+  using __llvm_libc::testing::ErrnoSetterMatcher::Fails;
+  using __llvm_libc::testing::ErrnoSetterMatcher::Succeeds;
+  constexpr const char *TEST_FILE = "testdata/dup.test";
+  int fd = __llvm_libc::open(TEST_FILE, O_WRONLY | O_CREAT, S_IRWXU);
+  ASSERT_EQ(errno, 0);
+  ASSERT_GT(fd, 0);
+  int dupfd = __llvm_libc::dup3(fd, DUPFD, 0);
+  ASSERT_EQ(errno, 0);
+  ASSERT_EQ(dupfd, DUPFD);
+
+  // Write something via the dup
+  constexpr char WRITE_DATA[] = "Hello, dup!";
+  constexpr size_t WRITE_SIZE = sizeof(WRITE_DATA);
+  ASSERT_EQ(ssize_t(WRITE_SIZE),
+            __llvm_libc::write(dupfd, WRITE_DATA, WRITE_SIZE));
+  ASSERT_THAT(__llvm_libc::close(dupfd), Succeeds(0));
+
+  // Reopen the file for reading and create a dup.
+  fd = __llvm_libc::open(TEST_FILE, O_RDONLY);
+  ASSERT_EQ(errno, 0);
+  ASSERT_GT(fd, 0);
+  dupfd = __llvm_libc::dup3(fd, DUPFD, 0);
+  ASSERT_EQ(errno, 0);
+  ASSERT_EQ(dupfd, DUPFD);
+
+  // Read the file content via the dup.
+  char buf[WRITE_SIZE];
+  ASSERT_THAT(__llvm_libc::read(dupfd, buf, WRITE_SIZE), Succeeds(WRITE_SIZE));
+  ASSERT_STREQ(buf, WRITE_DATA);
+
+  // Verify that, unlike dup2, duping to the same fd value with dup3 fails.
+  ASSERT_THAT(__llvm_libc::dup3(dupfd, dupfd, 0), Fails(EINVAL));
+
+  ASSERT_THAT(__llvm_libc::close(dupfd), Succeeds(0));
+  ASSERT_THAT(__llvm_libc::unlink(TEST_FILE), Succeeds(0));
+}
+
+TEST(LlvmLibcdupTest, DupBadFD) {
+  using __llvm_libc::testing::ErrnoSetterMatcher::Fails;
+  ASSERT_THAT(__llvm_libc::dup3(-1, 123, 0), Fails(EBADF));
+}

libc/test/src/unistd/dup_test.cpp

@@ -0,0 +1,59 @@
+//===-- Unittests for dup -------------------------------------------------===//
+//
+// 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/fcntl/open.h"
+#include "src/unistd/close.h"
+#include "src/unistd/dup.h"
+#include "src/unistd/read.h"
+#include "src/unistd/unlink.h"
+#include "src/unistd/write.h"
+#include "test/ErrnoSetterMatcher.h"
+#include "utils/UnitTest/Test.h"
+#include "utils/testutils/FDReader.h"
+
+#include <errno.h>
+
+TEST(LlvmLibcdupTest, ReadAndWriteViaDup) {
+  errno = 0;
+  using __llvm_libc::testing::ErrnoSetterMatcher::Succeeds;
+  constexpr const char *TEST_FILE = "testdata/dup.test";
+  int fd = __llvm_libc::open(TEST_FILE, O_WRONLY | O_CREAT, S_IRWXU);
+  ASSERT_EQ(errno, 0);
+  ASSERT_GT(fd, 0);
+  int dupfd = __llvm_libc::dup(fd);
+  ASSERT_EQ(errno, 0);
+  ASSERT_GT(dupfd, 0);
+
+  // Write something via the dup
+  constexpr char WRITE_DATA[] = "Hello, dup!";
+  constexpr size_t WRITE_SIZE = sizeof(WRITE_DATA);
+  ASSERT_EQ(ssize_t(WRITE_SIZE),
+            __llvm_libc::write(dupfd, WRITE_DATA, WRITE_SIZE));
+  ASSERT_THAT(__llvm_libc::close(dupfd), Succeeds(0));
+
+  // Reopen the file for reading and create a dup.
+  fd = __llvm_libc::open(TEST_FILE, O_RDONLY);
+  ASSERT_EQ(errno, 0);
+  ASSERT_GT(fd, 0);
+  dupfd = __llvm_libc::dup(fd);
+  ASSERT_EQ(errno, 0);
+  ASSERT_GT(dupfd, 0);
+
+  // Read the file content via the dup.
+  char buf[WRITE_SIZE];
+  ASSERT_THAT(__llvm_libc::read(dupfd, buf, WRITE_SIZE), Succeeds(WRITE_SIZE));
+  ASSERT_STREQ(buf, WRITE_DATA);
+
+  ASSERT_THAT(__llvm_libc::close(dupfd), Succeeds(0));
+  ASSERT_THAT(__llvm_libc::unlink(TEST_FILE), Succeeds(0));
+}
+
+TEST(LlvmLibcdupTest, DupBadFD) {
+  using __llvm_libc::testing::ErrnoSetterMatcher::Fails;
+  ASSERT_THAT(__llvm_libc::dup(-1), Fails(EBADF));
+}