[libc][NFC] Use operator delete to cleanup a File object.

The File API has been refactored to allow cleanup using operator delete.

Reviewed By: lntue

Differential Revision: https://reviews.llvm.org/D140574

7 files changed, 109 insertions, 68 deletions

diff --git a/libc/src/__support/File/file.cpp b/libc/src/__support/File/file.cpp
index 1493633718e6..53fa06b10c8a 100644
--- a/libc/src/__support/File/file.cpp
+++ b/libc/src/__support/File/file.cpp
@@ -338,26 +338,6 @@ int File::flush_unlocked() {
   return 0;
 }
 
-int File::close() {
-  {
-    FileLock lock(this);
-    if (prev_op == FileOp::WRITE && pos > 0) {
-      auto buf_result = platform_write(this, buf, pos);
-      if (buf_result.has_error() || buf_result.value < pos) {
-        err = true;
-        return buf_result.error;
-      }
-    }
-    int result = platform_close(this);
-    if (result != 0)
-      return result;
-    if (own_buf)
-      free(buf);
-  }
-  free(this);
-  return 0;
-}
-
 int File::set_buffer(void *buffer, size_t size, int buffer_mode) {
   // We do not need to lock the file as this method should be called before
   // other operations are performed on the file.
diff --git a/libc/src/__support/File/file.h b/libc/src/__support/File/file.h
index 3828694cbf03..2299584c3d64 100644
--- a/libc/src/__support/File/file.h
+++ b/libc/src/__support/File/file.h
@@ -9,6 +9,7 @@
 #ifndef LLVM_LIBC_SRC_SUPPORT_OSUTIL_FILE_H
 #define LLVM_LIBC_SRC_SUPPORT_OSUTIL_FILE_H
 
+#include "src/__support/CPP/new.h"
 #include "src/__support/error_or.h"
 #include "src/__support/threads/mutex.h"
 
@@ -46,6 +47,16 @@ public:
   using SeekFunc = ErrorOr<long>(File *, long, int);
   using CloseFunc = int(File *);
   using FlushFunc = int(File *);
+  // CleanupFunc is a function which does the equivalent of this:
+  //
+  // void my_file_cleanup(File *f) {
+  //   MyFile *file = reinterpret_cast<MyFile *>(f);
+  //   delete file;
+  // }
+  //
+  // Essentially, it a function which calls the delete operator on the
+  // platform file object to cleanup resources held by it.
+  using CleanupFunc = void(File *);
 
   using ModeFlags = uint32_t;
 
@@ -83,6 +94,7 @@ private:
   SeekFunc *platform_seek;
   CloseFunc *platform_close;
   FlushFunc *platform_flush;
+  CleanupFunc *platform_cleanup;
 
   Mutex mutex;
 
@@ -130,6 +142,26 @@ private:
     FileLock(FileLock &&) = delete;
   };
 
+  // This is private function and is not to be called by the users of
+  // File and its derived classes. The correct way to close a file is
+  // to call the File::cleanup function.
+  int close() {
+    {
+      FileLock lock(this);
+      if (prev_op == FileOp::WRITE && pos > 0) {
+        auto buf_result = platform_write(this, buf, pos);
+        if (buf_result.has_error() || buf_result.value < pos) {
+          err = true;
+          return buf_result.error;
+        }
+      }
+      int result = platform_close(this);
+      if (result != 0)
+        return result;
+    }
+    return 0;
+  }
+
 protected:
   constexpr bool write_allowed() const {
     return mode & (static_cast<ModeFlags>(OpenMode::WRITE) |
@@ -142,6 +174,11 @@ protected:
                    static_cast<ModeFlags>(OpenMode::PLUS));
   }
 
+  ~File() {
+    if (own_buf)
+      delete buf;
+  }
+
 public:
   // We want this constructor to be constexpr so that global file objects
   // like stdout do not require invocation of the constructor which can
@@ -151,16 +188,29 @@ public:
   // is zero. This way, we will not have to employ the semantics of
   // the set_buffer method and allocate a buffer.
   constexpr File(WriteFunc *wf, ReadFunc *rf, SeekFunc *sf, CloseFunc *cf,
-                 FlushFunc *ff, uint8_t *buffer, size_t buffer_size,
-                 int buffer_mode, bool owned, ModeFlags modeflags)
+                 FlushFunc *ff, CleanupFunc *clf, uint8_t *buffer,
+                 size_t buffer_size, int buffer_mode, bool owned,
+                 ModeFlags modeflags)
       : platform_write(wf), platform_read(rf), platform_seek(sf),
-        platform_close(cf), platform_flush(ff), mutex(false, false, false),
-        ungetc_buf(0), buf(buffer), bufsize(buffer_size), bufmode(buffer_mode),
-        own_buf(owned), mode(modeflags), pos(0), prev_op(FileOp::NONE),
-        read_limit(0), eof(false), err(false) {
+        platform_close(cf), platform_flush(ff), platform_cleanup(clf),
+        mutex(false, false, false), ungetc_buf(0), buf(buffer),
+        bufsize(buffer_size), bufmode(buffer_mode), own_buf(owned),
+        mode(modeflags), pos(0), prev_op(FileOp::NONE), read_limit(0),
+        eof(false), err(false) {
     adjust_buf();
   }
 
+  // Close |f| and cleanup resources held by it.
+  // Returns the non-zero error value if an error occurs when closing the
+  // file.
+  static constexpr int cleanup(File *f) {
+    int close_result = f->close();
+    if (close_result != 0)
+      return close_result;
+    f->platform_cleanup(f);
+    return 0;
+  }
+
   // Buffered write of |len| bytes from |data| without the file lock.
   FileIOResult write_unlocked(const void *data, size_t len);
 
@@ -214,9 +264,6 @@ public:
   // is ENOMEM.
   int set_buffer(void *buffer, size_t size, int buffer_mode);
 
-  // Closes the file stream and frees up all resources owned by it.
-  int close();
-
   void lock() { mutex.lock(); }
   void unlock() { mutex.unlock(); }
 
@@ -273,6 +320,15 @@ private:
   }
 };
 
+// Platform specific file implementations can simply pass a pointer to a
+// a specialization of this function as the CleanupFunc argument to the
+// File constructor. The template type argument FileType should replaced
+// with the type of the platform specific file implementation.
+template <typename FileType> void cleanup_file(File *f) {
+  auto *file = reinterpret_cast<FileType *>(f);
+  delete file;
+}
+
 // The implementaiton of this function is provided by the platfrom_file
 // library.
 ErrorOr<File *> openfile(const char *path, const char *mode);
diff --git a/libc/src/__support/File/linux_file.cpp b/libc/src/__support/File/linux_file.cpp
index 13de7c46994e..be6c61b58ecf 100644
--- a/libc/src/__support/File/linux_file.cpp
+++ b/libc/src/__support/File/linux_file.cpp
@@ -35,7 +35,8 @@ public:
   constexpr LinuxFile(int file_descriptor, uint8_t *buffer, size_t buffer_size,
                       int buffer_mode, bool owned, File::ModeFlags modeflags)
       : File(&write_func, &read_func, &seek_func, &close_func, flush_func,
-             buffer, buffer_size, buffer_mode, owned, modeflags),
+             &cleanup_file<LinuxFile>, buffer, buffer_size, buffer_mode, owned,
+             modeflags),
         fd(file_descriptor) {}
 
   int get_fd() const { return fd; }
diff --git a/libc/src/stdio/fclose.cpp b/libc/src/stdio/fclose.cpp
index c287442dc001..b4a366af1443 100644
--- a/libc/src/stdio/fclose.cpp
+++ b/libc/src/stdio/fclose.cpp
@@ -15,7 +15,8 @@
 namespace __llvm_libc {
 
 LLVM_LIBC_FUNCTION(int, fclose, (::FILE * stream)) {
-  int result = reinterpret_cast<__llvm_libc::File *>(stream)->close();
+  auto *file = reinterpret_cast<__llvm_libc::File *>(stream);
+  int result = File::cleanup(file);
   if (result != 0) {
     errno = result;
     return EOF;
diff --git a/libc/src/stdio/fopencookie.cpp b/libc/src/stdio/fopencookie.cpp
index a48e28f1324e..2e3cce7e6672 100644
--- a/libc/src/stdio/fopencookie.cpp
+++ b/libc/src/stdio/fopencookie.cpp
@@ -32,8 +32,9 @@ public:
   CookieFile(void *c, cookie_io_functions_t cops, uint8_t *buffer,
              size_t bufsize, File::ModeFlags mode)
       : File(&cookie_write, &cookie_read, &CookieFile::cookie_seek,
-             &cookie_close, &cookie_flush, buffer, bufsize,
-             0 /* default buffering mode */, true /* File owns buffer */, mode),
+             &cookie_close, &cookie_flush, &cleanup_file<CookieFile>, buffer,
+             bufsize, 0 /* default buffering mode */,
+             true /* File owns buffer */, mode),
         cookie(c), ops(cops) {}
 };
 
diff --git a/libc/test/src/__support/File/file_test.cpp b/libc/test/src/__support/File/file_test.cpp
index f3690e492534..6dbf2c0278fc 100644
--- a/libc/test/src/__support/File/file_test.cpp
+++ b/libc/test/src/__support/File/file_test.cpp
@@ -18,9 +18,10 @@
 using ModeFlags = __llvm_libc::File::ModeFlags;
 using MemoryView = __llvm_libc::memory::testing::MemoryView;
 using __llvm_libc::ErrorOr;
+using __llvm_libc::File;
 using __llvm_libc::FileIOResult;
 
-class StringFile : public __llvm_libc::File {
+class StringFile : public File {
   static constexpr size_t SIZE = 512;
   size_t pos;
   char str[SIZE] = {0};
@@ -38,8 +39,9 @@ public:
   explicit StringFile(char *buffer, size_t buflen, int bufmode, bool owned,
                       ModeFlags modeflags)
       : __llvm_libc::File(&str_write, &str_read, &str_seek, &str_close,
-                          &str_flush, reinterpret_cast<uint8_t *>(buffer),
-                          buflen, bufmode, owned, modeflags),
+                          &str_flush, &__llvm_libc::cleanup_file<StringFile>,
+                          reinterpret_cast<uint8_t *>(buffer), buflen, bufmode,
+                          owned, modeflags),
         pos(0), eof_marker(0), write_append(false) {
     if (modeflags & static_cast<ModeFlags>(__llvm_libc::File::OpenMode::APPEND))
       write_append = true;
@@ -144,7 +146,7 @@ TEST(LlvmLibcFileTest, WriteOnly) {
     EXPECT_TRUE(result.has_error());
   }
 
-  ASSERT_EQ(f->close(), 0);
+  ASSERT_EQ(File::cleanup(f), 0);
 }
 
 TEST(LlvmLibcFileTest, WriteLineBuffered) {
@@ -203,8 +205,8 @@ TEST(LlvmLibcFileTest, WriteLineBuffered) {
   EXPECT_MEM_EQ(src3, dst_line_final);
   EXPECT_MEM_EQ(src3, dst_full_final);
 
-  ASSERT_EQ(f_line->close(), 0);
-  ASSERT_EQ(f_full->close(), 0);
+  ASSERT_EQ(File::cleanup(f_line), 0);
+  ASSERT_EQ(File::cleanup(f_full), 0);
 }
 
 TEST(LlvmLibcFileTest, WriteUnbuffered) {
@@ -219,7 +221,7 @@ TEST(LlvmLibcFileTest, WriteUnbuffered) {
             sizeof(data)); // no buffering means this is written immediately.
   EXPECT_STREQ(f->get_str(), data);
 
-  ASSERT_EQ(f->close(), 0);
+  ASSERT_EQ(File::cleanup(f), 0);
 }
 
 TEST(LlvmLibcFileTest, ReadOnly) {
@@ -272,7 +274,7 @@ TEST(LlvmLibcFileTest, ReadOnly) {
     EXPECT_TRUE(result.has_error());
   }
 
-  ASSERT_EQ(f->close(), 0);
+  ASSERT_EQ(File::cleanup(f), 0);
 }
 
 TEST(LlvmLibcFileTest, ReadSeekCurAndRead) {
@@ -294,7 +296,7 @@ TEST(LlvmLibcFileTest, ReadSeekCurAndRead) {
   ASSERT_EQ(f->seek(-5, SEEK_CUR).value(), 0);
   ASSERT_EQ(f->read(data, READ_SIZE - 1).value, READ_SIZE - 1);
   ASSERT_STREQ(data, "9098");
-  ASSERT_EQ(f->close(), 0);
+  ASSERT_EQ(File::cleanup(f), 0);
 }
 
 TEST(LlvmLibcFileTest, AppendOnly) {
@@ -324,7 +326,7 @@ TEST(LlvmLibcFileTest, AppendOnly) {
   EXPECT_EQ(f->flush(), int(0));
   EXPECT_EQ(f->get_pos(), sizeof(write_data) + sizeof(initial_content));
 
-  ASSERT_EQ(f->close(), 0);
+  ASSERT_EQ(File::cleanup(f), 0);
 }
 
 TEST(LlvmLibcFileTest, WriteUpdate) {
@@ -344,7 +346,7 @@ TEST(LlvmLibcFileTest, WriteUpdate) {
   ASSERT_EQ(f->read(read_data, sizeof(data)).value, sizeof(data));
   EXPECT_STREQ(read_data, data);
 
-  ASSERT_EQ(f->close(), 0);
+  ASSERT_EQ(File::cleanup(f), 0);
 }
 
 TEST(LlvmLibcFileTest, ReadUpdate) {
@@ -377,7 +379,7 @@ TEST(LlvmLibcFileTest, ReadUpdate) {
       src2(write_data, sizeof(write_data));
   EXPECT_MEM_EQ(src2, dst2);
 
-  ASSERT_EQ(f->close(), 0);
+  ASSERT_EQ(File::cleanup(f), 0);
 }
 
 TEST(LlvmLibcFileTest, AppendUpdate) {
@@ -419,7 +421,7 @@ TEST(LlvmLibcFileTest, AppendUpdate) {
   MemoryView src4(initial_content, READ_SIZE), dst4(read_data, READ_SIZE);
   EXPECT_MEM_EQ(src4, dst4);
 
-  ASSERT_EQ(f->close(), 0);
+  ASSERT_EQ(File::cleanup(f), 0);
 }
 
 TEST(LlvmLibcFileTest, SmallBuffer) {
@@ -436,7 +438,7 @@ TEST(LlvmLibcFileTest, SmallBuffer) {
   EXPECT_EQ(f->get_pos(), sizeof(WRITE_DATA));
   ASSERT_STREQ(f->get_str(), WRITE_DATA);
 
-  ASSERT_EQ(f->close(), 0);
+  ASSERT_EQ(File::cleanup(f), 0);
 }
 
 TEST(LlvmLibcFileTest, ZeroLengthBuffer) {
@@ -458,9 +460,9 @@ TEST(LlvmLibcFileTest, ZeroLengthBuffer) {
   ASSERT_STREQ(f_lbf->get_str(), WRITE_DATA);
   ASSERT_STREQ(f_nbf->get_str(), WRITE_DATA);
 
-  ASSERT_EQ(f_fbf->close(), 0);
-  ASSERT_EQ(f_lbf->close(), 0);
-  ASSERT_EQ(f_nbf->close(), 0);
+  ASSERT_EQ(File::cleanup(f_fbf), 0);
+  ASSERT_EQ(File::cleanup(f_lbf), 0);
+  ASSERT_EQ(File::cleanup(f_nbf), 0);
 }
 
 TEST(LlvmLibcFileTest, WriteNothing) {
@@ -485,7 +487,7 @@ TEST(LlvmLibcFileTest, WriteNothing) {
   ASSERT_FALSE(f_lbf->error_unlocked());
   ASSERT_FALSE(f_nbf->error_unlocked());
 
-  ASSERT_EQ(f_fbf->close(), 0);
-  ASSERT_EQ(f_lbf->close(), 0);
-  ASSERT_EQ(f_nbf->close(), 0);
+  ASSERT_EQ(File::cleanup(f_fbf), 0);
+  ASSERT_EQ(File::cleanup(f_lbf), 0);
+  ASSERT_EQ(File::cleanup(f_nbf), 0);
 }
diff --git a/libc/test/src/__support/File/platform_file_test.cpp b/libc/test/src/__support/File/platform_file_test.cpp
index 51f7f9aeea03..abbd8113846a 100644
--- a/libc/test/src/__support/File/platform_file_test.cpp
+++ b/libc/test/src/__support/File/platform_file_test.cpp
@@ -20,7 +20,7 @@ TEST(LlvmLibcPlatformFileTest, CreateWriteCloseAndReadBack) {
   File *file = __llvm_libc::openfile(FILENAME, "w");
   ASSERT_FALSE(file == nullptr);
   ASSERT_EQ(file->write(TEXT, TEXT_SIZE).value, TEXT_SIZE);
-  ASSERT_EQ(file->close(), 0);
+  ASSERT_EQ(File::cleanup(file), 0);
 
   file = __llvm_libc::openfile(FILENAME, "r");
   ASSERT_FALSE(file == nullptr);
@@ -33,7 +33,7 @@ TEST(LlvmLibcPlatformFileTest, CreateWriteCloseAndReadBack) {
   ASSERT_EQ(file->read(data, TEXT_SIZE).value, size_t(0));
   ASSERT_TRUE(file->iseof());
 
-  ASSERT_EQ(file->close(), 0);
+  ASSERT_EQ(File::cleanup(file), 0);
 }
 
 TEST(LlvmLibcPlatformFileTest, CreateWriteSeekAndReadBack) {
@@ -53,7 +53,7 @@ TEST(LlvmLibcPlatformFileTest, CreateWriteSeekAndReadBack) {
   ASSERT_EQ(file->read(data, TEXT_SIZE).value, size_t(0));
   ASSERT_TRUE(file->iseof());
 
-  ASSERT_EQ(file->close(), 0);
+  ASSERT_EQ(File::cleanup(file), 0);
 }
 
 TEST(LlvmLibcPlatformFileTest, CreateAppendCloseAndReadBack) {
@@ -61,14 +61,14 @@ TEST(LlvmLibcPlatformFileTest, CreateAppendCloseAndReadBack) {
   File *file = __llvm_libc::openfile(FILENAME, "w");
   ASSERT_FALSE(file == nullptr);
   ASSERT_EQ(file->write(TEXT, TEXT_SIZE).value, TEXT_SIZE);
-  ASSERT_EQ(file->close(), 0);
+  ASSERT_EQ(File::cleanup(file), 0);
 
   file = __llvm_libc::openfile(FILENAME, "a");
   ASSERT_FALSE(file == nullptr);
   constexpr char APPEND_TEXT[] = " Append Text";
   constexpr size_t APPEND_TEXT_SIZE = sizeof(APPEND_TEXT) - 1;
   ASSERT_EQ(file->write(APPEND_TEXT, APPEND_TEXT_SIZE).value, APPEND_TEXT_SIZE);
-  ASSERT_EQ(file->close(), 0);
+  ASSERT_EQ(File::cleanup(file), 0);
 
   file = __llvm_libc::openfile(FILENAME, "r");
   ASSERT_FALSE(file == nullptr);
@@ -82,7 +82,7 @@ TEST(LlvmLibcPlatformFileTest, CreateAppendCloseAndReadBack) {
   ASSERT_EQ(file->read(data, READ_SIZE).value, size_t(0));
   ASSERT_TRUE(file->iseof());
 
-  ASSERT_EQ(file->close(), 0);
+  ASSERT_EQ(File::cleanup(file), 0);
 }
 
 TEST(LlvmLibcPlatformFileTest, CreateAppendSeekAndReadBack) {
@@ -90,7 +90,7 @@ TEST(LlvmLibcPlatformFileTest, CreateAppendSeekAndReadBack) {
   File *file = __llvm_libc::openfile(FILENAME, "w");
   ASSERT_FALSE(file == nullptr);
   ASSERT_EQ(file->write(TEXT, TEXT_SIZE).value, TEXT_SIZE);
-  ASSERT_EQ(file->close(), 0);
+  ASSERT_EQ(File::cleanup(file), 0);
 
   file = __llvm_libc::openfile(FILENAME, "a+");
   ASSERT_FALSE(file == nullptr);
@@ -108,7 +108,7 @@ TEST(LlvmLibcPlatformFileTest, CreateAppendSeekAndReadBack) {
   ASSERT_EQ(file->read(data, APPEND_TEXT_SIZE).value, size_t(0));
   ASSERT_TRUE(file->iseof());
 
-  ASSERT_EQ(file->close(), 0);
+  ASSERT_EQ(File::cleanup(file), 0);
 }
 
 TEST(LlvmLibcPlatformFileTest, LargeFile) {
@@ -126,7 +126,7 @@ TEST(LlvmLibcPlatformFileTest, LargeFile) {
   for (int i = 0; i < REPEAT; ++i) {
     ASSERT_EQ(file->write(write_data, DATA_SIZE).value, DATA_SIZE);
   }
-  ASSERT_EQ(file->close(), 0);
+  ASSERT_EQ(File::cleanup(file), 0);
 
   file = __llvm_libc::openfile(FILENAME, "r");
   ASSERT_FALSE(file == nullptr);
@@ -141,7 +141,7 @@ TEST(LlvmLibcPlatformFileTest, LargeFile) {
   ASSERT_EQ(file->read(data, 1).value, size_t(0));
   ASSERT_TRUE(file->iseof());
 
-  ASSERT_EQ(file->close(), 0);
+  ASSERT_EQ(File::cleanup(file), 0);
 }
 
 TEST(LlvmLibcPlatformFileTest, ReadSeekCurAndRead) {
@@ -151,7 +151,7 @@ TEST(LlvmLibcPlatformFileTest, ReadSeekCurAndRead) {
   constexpr char CONTENT[] = "1234567890987654321";
   ASSERT_EQ(sizeof(CONTENT) - 1,
             file->write(CONTENT, sizeof(CONTENT) - 1).value);
-  ASSERT_EQ(0, file->close());
+  ASSERT_EQ(0, File::cleanup(file));
 
   file = __llvm_libc::openfile(FILENAME, "r");
   ASSERT_FALSE(file == nullptr);
@@ -168,7 +168,7 @@ TEST(LlvmLibcPlatformFileTest, ReadSeekCurAndRead) {
   ASSERT_EQ(file->read(data, READ_SIZE - 1).value, READ_SIZE - 1);
   ASSERT_STREQ(data, "9098");
 
-  ASSERT_EQ(file->close(), 0);
+  ASSERT_EQ(File::cleanup(file), 0);
 }
 
 TEST(LlvmLibcPlatformFileTest, IncorrectOperation) {
@@ -180,21 +180,21 @@ TEST(LlvmLibcPlatformFileTest, IncorrectOperation) {
   ASSERT_EQ(file->read(data, 1).value, size_t(0)); // Cannot read
   ASSERT_FALSE(file->iseof());
   ASSERT_TRUE(file->error());
-  ASSERT_EQ(file->close(), 0);
+  ASSERT_EQ(File::cleanup(file), 0);
 
   file = __llvm_libc::openfile(FILENAME, "r");
   ASSERT_FALSE(file == nullptr);
   ASSERT_EQ(file->write(data, 1).value, size_t(0)); // Cannot write
   ASSERT_FALSE(file->iseof());
   ASSERT_TRUE(file->error());
-  ASSERT_EQ(file->close(), 0);
+  ASSERT_EQ(File::cleanup(file), 0);
 
   file = __llvm_libc::openfile(FILENAME, "a");
   ASSERT_FALSE(file == nullptr);
   ASSERT_EQ(file->read(data, 1).value, size_t(0)); // Cannot read
   ASSERT_FALSE(file->iseof());
   ASSERT_TRUE(file->error());
-  ASSERT_EQ(file->close(), 0);
+  ASSERT_EQ(File::cleanup(file), 0);
 }
 
 TEST(LlvmLibcPlatformFileTest, StdOutStdErrSmokeTest) {