Add File::Duplicate to duplicate a file handle.
BUG=462584
R=rvargas@chromium.org
Review URL: https://codereview.chromium.org/1017243002
Cr-Commit-Position: refs/heads/master@{#321389}
CrOS-Libchrome-Original-Commit: bad5603dd8bbcf7583e8e483f8198e9b88f1c079
diff --git a/base/files/file.h b/base/files/file.h
index db04871..13c8a96 100644
--- a/base/files/file.h
+++ b/base/files/file.h
@@ -288,6 +288,13 @@
// Unlock a file previously locked.
Error Unlock();
+ // Returns a new object referencing this file for use within the current
+ // process. Handling of FLAG_DELETE_ON_CLOSE varies by OS. On POSIX, the File
+ // object that was created or initialized with this flag will have unlinked
+ // the underlying file when it was created or opened. On Windows, the
+ // underlying file is deleted when the last handle to it is closed.
+ File Duplicate();
+
bool async() const { return async_; }
#if defined(OS_WIN)
diff --git a/base/files/file_posix.cc b/base/files/file_posix.cc
index 663f099..517390f 100644
--- a/base/files/file_posix.cc
+++ b/base/files/file_posix.cc
@@ -463,6 +463,20 @@
return CallFctnlFlock(file_.get(), false);
}
+File File::Duplicate() {
+ if (!IsValid())
+ return File();
+
+ PlatformFile other_fd = dup(GetPlatformFile());
+ if (other_fd == -1)
+ return File(OSErrorToFileError(errno));
+
+ File other(other_fd);
+ if (async())
+ other.async_ = true;
+ return other.Pass();
+}
+
// Static.
File::Error File::OSErrorToFileError(int saved_errno) {
switch (saved_errno) {
diff --git a/base/files/file_unittest.cc b/base/files/file_unittest.cc
index 3bc2db6..5c59424 100644
--- a/base/files/file_unittest.cc
+++ b/base/files/file_unittest.cc
@@ -443,6 +443,49 @@
EXPECT_EQ(kOffset, file.Seek(base::File::FROM_END, -kOffset));
}
+TEST(FileTest, Duplicate) {
+ base::ScopedTempDir temp_dir;
+ ASSERT_TRUE(temp_dir.CreateUniqueTempDir());
+ FilePath file_path = temp_dir.path().AppendASCII("file");
+ File file(file_path,(base::File::FLAG_CREATE |
+ base::File::FLAG_READ |
+ base::File::FLAG_WRITE));
+ ASSERT_TRUE(file.IsValid());
+
+ File file2(file.Duplicate());
+ ASSERT_TRUE(file2.IsValid());
+
+ // Write through one handle, close it, read through the other.
+ static const char kData[] = "now is a good time.";
+ static const int kDataLen = sizeof(kData) - 1;
+
+ ASSERT_EQ(0, file.Seek(base::File::FROM_CURRENT, 0));
+ ASSERT_EQ(0, file2.Seek(base::File::FROM_CURRENT, 0));
+ ASSERT_EQ(kDataLen, file.WriteAtCurrentPos(kData, kDataLen));
+ ASSERT_EQ(kDataLen, file.Seek(base::File::FROM_CURRENT, 0));
+ ASSERT_EQ(kDataLen, file2.Seek(base::File::FROM_CURRENT, 0));
+ file.Close();
+ char buf[kDataLen];
+ ASSERT_EQ(kDataLen, file2.Read(0, &buf[0], kDataLen));
+ ASSERT_EQ(std::string(kData, kDataLen), std::string(&buf[0], kDataLen));
+}
+
+TEST(FileTest, DuplicateDeleteOnClose) {
+ base::ScopedTempDir temp_dir;
+ ASSERT_TRUE(temp_dir.CreateUniqueTempDir());
+ FilePath file_path = temp_dir.path().AppendASCII("file");
+ File file(file_path,(base::File::FLAG_CREATE |
+ base::File::FLAG_READ |
+ base::File::FLAG_WRITE |
+ base::File::FLAG_DELETE_ON_CLOSE));
+ ASSERT_TRUE(file.IsValid());
+ File file2(file.Duplicate());
+ ASSERT_TRUE(file2.IsValid());
+ file.Close();
+ file2.Close();
+ ASSERT_FALSE(base::PathExists(file_path));
+}
+
#if defined(OS_WIN)
TEST(FileTest, GetInfoForDirectory) {
base::ScopedTempDir temp_dir;