[libc] Add implementations of feof, ferror and clearerr.

The corresponding _unlocked functions have also been added.

Reviewed By: lntue, michaelrj

Differential Revision: https://reviews.llvm.org/D124311

Author: Siva Chandra Reddy

libc/config/linux/x86_64/entrypoints.txt

@@ -251,8 +251,14 @@ if(LLVM_LIBC_FULL_BUILD)
     libc.src.stdlib.getenv
 
     # stdio.h entrypoints
+    libc.src.stdio.clearerr
+    libc.src.stdio.clearerr_unlocked
     libc.src.stdio.fclose
     libc.src.stdio.flockfile
+    libc.src.stdio.feof
+    libc.src.stdio.feof_unlocked
+    libc.src.stdio.ferror
+    libc.src.stdio.ferror_unlocked
     libc.src.stdio.fflush
     libc.src.stdio.fopen
     libc.src.stdio.fopencookie

libc/spec/gnu_ext.td

@@ -72,6 +72,21 @@ def GnuExtensions : StandardSpec<"GNUExtensions"> {
       [CookieIOFunctionsT], // Types
       [], // Enumerations
       [
+          FunctionSpec<
+              "clearerr_unlocked",
+              RetValSpec<VoidType>,
+              [ArgSpec<FILEPtr>]
+          >,
+          FunctionSpec<
+              "feof_unlocked",
+              RetValSpec<IntType>,
+              [ArgSpec<FILEPtr>]
+          >,
+          FunctionSpec<
+              "ferror_unlocked",
+              RetValSpec<IntType>,
+              [ArgSpec<FILEPtr>]
+          >,
           FunctionSpec<
               "fopencookie",
               RetValSpec<FILEPtr>,

libc/spec/stdc.td

@@ -478,11 +478,26 @@ def StdC : StandardSpec<"stdc"> {
       ],
       [], // Enumerations
       [
+          FunctionSpec<
+              "clearerr",
+              RetValSpec<VoidType>,
+              [ArgSpec<FILEPtr>]
+          >,
           FunctionSpec<
               "fclose",
               RetValSpec<IntType>,
               [ArgSpec<FILEPtr>]
           >,
+          FunctionSpec<
+              "feof",
+              RetValSpec<IntType>,
+              [ArgSpec<FILEPtr>]
+          >,
+          FunctionSpec<
+              "ferror",
+              RetValSpec<IntType>,
+              [ArgSpec<FILEPtr>]
+          >,
           FunctionSpec<
               "fflush",
               RetValSpec<IntType>,

libc/src/__support/File/file.h

@@ -97,6 +97,19 @@ class File {
   bool eof;
   bool err;
 
+  // This is a convenience RAII class to lock and unlock file objects.
+  class FileLock {
+    File *file;
+
+  public:
+    explicit FileLock(File *f) : file(f) { file->lock(); }
+
+    ~FileLock() { file->unlock(); }
+
+    FileLock(const FileLock &) = delete;
+    FileLock(FileLock &&) = delete;
+  };
+
 protected:
   bool write_allowed() const {
     return mode & (static_cast<ModeFlags>(OpenMode::WRITE) |
@@ -150,21 +163,17 @@ class File {
 
   // Buffered write of |len| bytes from |data| under the file lock.
   size_t write(const void *data, size_t len) {
-    lock();
-    size_t ret = write_unlocked(data, len);
-    unlock();
-    return ret;
+    FileLock l(this);
+    return write_unlocked(data, len);
   }
 
   // Buffered read of |len| bytes into |data| without the file lock.
   size_t read_unlocked(void *data, size_t len);
 
   // Buffered read of |len| bytes into |data| under the file lock.
   size_t read(void *data, size_t len) {
-    lock();
-    size_t ret = read_unlocked(data, len);
-    unlock();
-    return ret;
+    FileLock l(this);
+    return read_unlocked(data, len);
   }
 
   int seek(long offset, int whence);
@@ -184,26 +193,30 @@ class File {
   void lock() { mutex.lock(); }
   void unlock() { mutex.unlock(); }
 
-  bool error() const { return err; }
-  void clearerr() { err = false; }
-  bool iseof() const { return eof; }
+  bool error_unlocked() const { return err; }
 
-  // Returns an bit map of flags corresponding to enumerations of
-  // OpenMode, ContentType and CreateType.
-  static ModeFlags mode_flags(const char *mode);
-};
+  bool error() {
+    FileLock l(this);
+    return error_unlocked();
+  }
 
-// This is a convenience RAII class to lock and unlock file objects.
-class FileLock {
-  File *file;
+  void clearerr_unlocked() { err = false; }
 
-public:
-  explicit FileLock(File *f) : file(f) { file->lock(); }
+  void clearerr() {
+    FileLock l(this);
+    clearerr_unlocked();
+  }
+
+  bool iseof_unlocked() { return eof; }
 
-  ~FileLock() { file->unlock(); }
+  bool iseof() {
+    FileLock l(this);
+    return iseof_unlocked();
+  }
 
-  FileLock(const FileLock &) = delete;
-  FileLock(FileLock &&) = delete;
+  // Returns an bit map of flags corresponding to enumerations of
+  // OpenMode, ContentType and CreateType.
+  static ModeFlags mode_flags(const char *mode);
 };
 
 // The implementaiton of this function is provided by the platfrom_file

libc/src/stdio/CMakeLists.txt

@@ -24,6 +24,78 @@ add_entrypoint_object(
     libc.src.__support.File.platform_file
 )
 
+add_entrypoint_object(
+  clearerr
+  SRCS
+    clearerr.cpp
+  HDRS
+    clearerr.h
+  DEPENDS
+    libc.include.stdio
+    libc.src.__support.File.file
+    libc.src.__support.File.platform_file
+)
+
+add_entrypoint_object(
+  clearerr_unlocked
+  SRCS
+    clearerr_unlocked.cpp
+  HDRS
+    clearerr_unlocked.h
+  DEPENDS
+    libc.include.stdio
+    libc.src.__support.File.file
+    libc.src.__support.File.platform_file
+)
+
+add_entrypoint_object(
+  feof
+  SRCS
+    feof.cpp
+  HDRS
+    feof.h
+  DEPENDS
+    libc.include.stdio
+    libc.src.__support.File.file
+    libc.src.__support.File.platform_file
+)
+
+add_entrypoint_object(
+  feof_unlocked
+  SRCS
+    feof_unlocked.cpp
+  HDRS
+    feof_unlocked.h
+  DEPENDS
+    libc.include.stdio
+    libc.src.__support.File.file
+    libc.src.__support.File.platform_file
+)
+
+add_entrypoint_object(
+  ferror
+  SRCS
+    ferror.cpp
+  HDRS
+    ferror.h
+  DEPENDS
+    libc.include.stdio
+    libc.src.__support.File.file
+    libc.src.__support.File.platform_file
+)
+
+add_entrypoint_object(
+  ferror_unlocked
+  SRCS
+    ferror_unlocked.cpp
+  HDRS
+    ferror_unlocked.h
+  DEPENDS
+    libc.include.stdio
+    libc.src.__support.File.file
+    libc.src.__support.File.platform_file
+)
+
 add_entrypoint_object(
   fflush
   SRCS

libc/src/stdio/clearerr.cpp

@@ -0,0 +1,20 @@
+//===-- Implementation of clearerr ----------------------------------------===//
+//
+// 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/clearerr.h"
+#include "src/__support/File/file.h"
+
+#include <stdio.h>
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(void, clearerr, (::FILE * stream)) {
+  reinterpret_cast<__llvm_libc::File *>(stream)->clearerr();
+}
+
+} // namespace __llvm_libc

libc/src/stdio/clearerr.h

@@ -0,0 +1,20 @@
+//===-- Implementation header of clearerr -----------------------*- 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_CLEARERR_H
+#define LLVM_LIBC_SRC_STDIO_CLEARERR_H
+
+#include <stdio.h>
+
+namespace __llvm_libc {
+
+void clearerr(::FILE *stream);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_STDIO_CLEARERR_H

libc/src/stdio/clearerr_unlocked.cpp

@@ -0,0 +1,20 @@
+//===-- Implementation of clearerr_unlocked -------------------------------===//
+//
+// 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/clearerr_unlocked.h"
+#include "src/__support/File/file.h"
+
+#include <stdio.h>
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(void, clearerr_unlocked, (::FILE * stream)) {
+  reinterpret_cast<__llvm_libc::File *>(stream)->clearerr_unlocked();
+}
+
+} // namespace __llvm_libc

libc/src/stdio/clearerr_unlocked.h

@@ -0,0 +1,20 @@
+//===-- Implementation header of clearerr_unlocked --------------*- 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_CLEARERR_UNLOCKED_H
+#define LLVM_LIBC_SRC_STDIO_CLEARERR_UNLOCKED_H
+
+#include <stdio.h>
+
+namespace __llvm_libc {
+
+void clearerr_unlocked(::FILE *stream);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_STDIO_CLEARERR_UNLOCKED_H

libc/src/stdio/feof.cpp

@@ -0,0 +1,20 @@
+//===-- Implementation of feof --------------------------------------------===//
+//
+// 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/feof.h"
+#include "src/__support/File/file.h"
+
+#include <stdio.h>
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, feof, (::FILE * stream)) {
+  return reinterpret_cast<__llvm_libc::File *>(stream)->iseof();
+}
+
+} // namespace __llvm_libc