[libc][POSIX] implement fseeko, ftello

libc/config/linux/x86_64/entrypoints.txt

@@ -681,6 +681,8 @@ if(LLVM_LIBC_FULL_BUILD)
     libc.src.stdio.fread_unlocked
     libc.src.stdio.fseek
     libc.src.stdio.ftell
+    libc.src.stdio.fseeko
+    libc.src.stdio.ftello
     libc.src.stdio.funlockfile
     libc.src.stdio.fwrite
     libc.src.stdio.fwrite_unlocked

libc/src/stdio/CMakeLists.txt

@@ -270,6 +270,8 @@ add_stdio_entrypoint_object(ferror)
 add_stdio_entrypoint_object(ferror_unlocked)
 add_stdio_entrypoint_object(fseek)
 add_stdio_entrypoint_object(ftell)
+add_stdio_entrypoint_object(fseeko)
+add_stdio_entrypoint_object(ftello)
 add_stdio_entrypoint_object(fflush)
 add_stdio_entrypoint_object(clearerr)
 add_stdio_entrypoint_object(clearerr_unlocked)

libc/src/stdio/fseeko.h

@@ -0,0 +1,20 @@
+//===-- Implementation header of fseeko -------------------------*- 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_FSEEKO_H
+#define LLVM_LIBC_SRC_STDIO_FSEEKO_H
+
+#include <stdio.h>
+
+namespace LIBC_NAMESPACE {
+
+int fseeko(::FILE *stream, off_t offset, int whence);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDIO_FSEEKO_H

libc/src/stdio/ftello.h

@@ -0,0 +1,20 @@
+//===-- Implementation header of ftello -------------------------*- 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_FTELLO_H
+#define LLVM_LIBC_SRC_STDIO_FTELLO_H
+
+#include <stdio.h>
+
+namespace LIBC_NAMESPACE {
+
+off_t ftello(::FILE *f);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDIO_FTELLO_H

libc/src/stdio/generic/CMakeLists.txt

@@ -121,6 +121,32 @@ add_entrypoint_object(
     libc.src.__support.File.platform_file
 )
 
+add_entrypoint_object(
+  fseeko
+  SRCS
+    fseeko.cpp
+  HDRS
+    ../fseeko.h
+  DEPENDS
+    libc.src.errno.errno
+    libc.include.stdio
+    libc.src.__support.File.file
+    libc.src.__support.File.platform_file
+)
+
+add_entrypoint_object(
+  ftello
+  SRCS
+    ftello.cpp
+  HDRS
+    ../ftello.h
+  DEPENDS
+    libc.src.errno.errno
+    libc.include.stdio
+    libc.src.__support.File.file
+    libc.src.__support.File.platform_file
+)
+
 add_entrypoint_object(
   fopen
   SRCS

libc/src/stdio/generic/fseeko.cpp

@@ -0,0 +1,27 @@
+//===-- Implementation of fseeko ------------------------------------------===//
+//
+// 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/fseeko.h"
+#include "src/__support/File/file.h"
+
+#include "src/errno/libc_errno.h"
+#include <stdio.h>
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(int, fseeko, (::FILE * stream, off_t offset, int whence)) {
+  auto result =
+      reinterpret_cast<LIBC_NAMESPACE::File *>(stream)->seek(offset, whence);
+  if (!result.has_value()) {
+    libc_errno = result.error();
+    return -1;
+  }
+  return 0;
+}
+
+} // namespace LIBC_NAMESPACE

libc/src/stdio/generic/ftello.cpp

@@ -0,0 +1,26 @@
+//===-- Implementation of ftello ------------------------------------------===//
+//
+// 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/ftello.h"
+#include "src/__support/File/file.h"
+
+#include "src/errno/libc_errno.h"
+#include <stdio.h>
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(off_t, ftello, (::FILE * stream)) {
+  auto result = reinterpret_cast<LIBC_NAMESPACE::File *>(stream)->tell();
+  if (!result.has_value()) {
+    libc_errno = result.error();
+    return -1;
+  }
+  return result.value();
+}
+
+} // namespace LIBC_NAMESPACE

libc/test/src/stdio/CMakeLists.txt

@@ -442,6 +442,8 @@ add_libc_test(
     libc.src.stdio.fread
     libc.src.stdio.fseek
     libc.src.stdio.ftell
+    libc.src.stdio.fseeko
+    libc.src.stdio.ftello
     libc.src.stdio.fwrite
     libc.src.stdio.setvbuf
 )

libc/test/src/stdio/ftell_test.cpp

@@ -10,7 +10,9 @@
 #include "src/stdio/fopen.h"
 #include "src/stdio/fread.h"
 #include "src/stdio/fseek.h"
+#include "src/stdio/fseeko.h"
 #include "src/stdio/ftell.h"
+#include "src/stdio/ftello.h"
 #include "src/stdio/fwrite.h"
 #include "src/stdio/setvbuf.h"
 #include "test/UnitTest/Test.h"
@@ -37,6 +39,13 @@ class LlvmLibcFTellTest : public LIBC_NAMESPACE::testing::Test {
     // still return the correct effective offset.
     ASSERT_EQ(size_t(LIBC_NAMESPACE::ftell(file)), WRITE_SIZE);
 
+    off_t offseto = 42;
+    ASSERT_EQ(0, LIBC_NAMESPACE::fseeko(file, offseto, SEEK_SET));
+    ASSERT_EQ(LIBC_NAMESPACE::ftello(file), offseto);
+    ASSERT_EQ(0, LIBC_NAMESPACE::fseeko(file, -offseto, SEEK_END));
+    ASSERT_EQ(size_t(LIBC_NAMESPACE::ftello(file)),
+              size_t(WRITE_SIZE - offseto));
+
     long offset = 5;
     ASSERT_EQ(0, LIBC_NAMESPACE::fseek(file, offset, SEEK_SET));
     ASSERT_EQ(LIBC_NAMESPACE::ftell(file), offset);