[libc] Add implementations of ftell.

[sivachandra]

Sorry, this is WiP and not complete - not sure why I did an arc diff instead of saving the work with git commit. I will update and ping when ready.

[sivachandra]

Uploading a complete implementation of ftell and ftello.

[sivachandra]

The patch is now complete.

[sivachandra]

Remove ftello - we will add it when we are more prepared to deal with
off_t variances.

[lntue]

libc/config/linux/api.td

160

Is off_t being used any where in the patch? Or just definition to be included in the headers?

[sivachandra]

Remove off_t from spec and config for stdio.h as it is not used anymore.

[sivachandra]

libc/config/linux/api.td

160

Ah yes! Removed now, from here and from spec/posix.td.

[michaelrj]

LGTM

libc/config/linux/api.td

let Macros = [
     SimpleMacroDef<"stderr", "stderr">,
     SimpleMacroDef<"stdin", "stdin">,
     SimpleMacroDef<"stdout", "stdout">,
     SimpleMacroDef<"_IOFBF", "0">,
     SimpleMacroDef<"_IOLBF", "1">,
     SimpleMacroDef<"_IONBF", "2">,
     SimpleMacroDef<"EOF", "-1">,
   ];
-  let Types = ["size_t", "FILE", "cookie_io_functions_t"];
+  let Types = ["off_t", "size_t", "FILE", "cookie_io_functions_t"];
 }
 
 def StdlibAPI : PublicAPI<"stdlib.h"> {
   let Types = [
     "div_t",
     "ldiv_t",
     "lldiv_t",
     "size_t",

libc/config/linux/x86_64/entrypoints.txt

list(APPEND TARGET_LIBC_ENTRYPOINTS
     libc.src.stdio.fflush
     libc.src.stdio.fopen
     libc.src.stdio.fputc
     libc.src.stdio.fputs
     libc.src.stdio.fopencookie
     libc.src.stdio.fread
     libc.src.stdio.fread_unlocked
     libc.src.stdio.fseek
+    libc.src.stdio.ftell
+    libc.src.stdio.ftello
     libc.src.stdio.funlockfile
     libc.src.stdio.fwrite
     libc.src.stdio.fwrite_unlocked
     libc.src.stdio.fprintf
     libc.src.stdio.printf
     libc.src.stdio.putc
     libc.src.stdio.putchar
     libc.src.stdio.puts

libc/include/CMakeLists.txt

add_gen_header(
   DEF_FILE stdio.h.def
   GEN_HDR stdio.h
   DEPENDS
     .llvm_libc_common_h
     .llvm-libc-macros.file_seek_macros
     .llvm-libc-macros.stdio_macros
     .llvm-libc-types.cookie_io_functions_t
     .llvm-libc-types.FILE
+    .llvm-libc-types.off_t
     .llvm-libc-types.size_t
 )
 
 add_gen_header(
   stdlib
   DEF_FILE stdlib.h.def
   GEN_HDR stdlib.h
   DEPENDS

libc/spec/posix.td

[
           [ArgSpec<PThreadOnceTPtr>, ArgSpec<PThreadOnceCallback>]
       >,
     ]
   >;
 
   HeaderSpec StdIO = HeaderSpec<
       "stdio.h",
       [], // Macros
-      [], // Types
+      [OffTType], // Types
       [], // Enumerations
       [
           FunctionSpec<
               "flockfile",
               RetValSpec<VoidType>,
               [ArgSpec<FILEPtr>]
           >,
           FunctionSpec<
               "funlockfile",
               RetValSpec<VoidType>,
               [ArgSpec<FILEPtr>]
           >,
+          FunctionSpec<
+              "ftello",
+              RetValSpec<OffTType>,
+              [ArgSpec<FILEPtr>]
+          >,
       ]
   >;
 
   HeaderSpec Dirent = HeaderSpec<
       "dirent.h",
       [], // Macros
       [InoT, StructDirent, DIR], // Types
       [], // Enumerations

libc/spec/stdc.td

HeaderSpec StdIO = HeaderSpec<
           >,
           FunctionSpec<
               "fputc",
               RetValSpec<IntType>,
               [ArgSpec<IntType>,
                ArgSpec<FILEPtr>]
           >,
           FunctionSpec<
+              "ftell",
+              RetValSpec<LongType>,
+              [ArgSpec<FILEPtr>]
+          >,
+          FunctionSpec<
               "putc",
               RetValSpec<IntType>,
               [ArgSpec<IntType>,
                ArgSpec<FILEPtr>]
           >,
           FunctionSpec<
               "putchar",
               RetValSpec<IntType>,

libc/src/__support/File/file.h

constexpr void adjust_buf() {
     }
   }
 };
 
 // The implementaiton of this function is provided by the platfrom_file
 // library.
 File *openfile(const char *path, const char *mode);
 
+// The platform_file library should implement it if it relevant for that
+// platform.
+int get_fileno(File *f);
+
 extern File *stdin;
 extern File *stdout;
 extern File *stderr;
 
 } // namespace __llvm_libc
 
 #endif // LLVM_LIBC_SRC_SUPPORT_OSUTIL_FILE_H

libc/src/__support/File/linux_file.cpp

#endif
 
   void *buffer = malloc(File::DEFAULT_BUFFER_SIZE);
   auto *file = reinterpret_cast<LinuxFile *>(malloc(sizeof(LinuxFile)));
   LinuxFile::init(file, fd, buffer, File::DEFAULT_BUFFER_SIZE, _IOFBF, true,
                   modeflags);
   return file;
 }
 
+int get_fileno(File *f) {
+  auto *lf = reinterpret_cast<LinuxFile *>(f);
+  return lf->get_fd();
+}
+
 constexpr size_t STDIN_BUFFER_SIZE = 512;
 char stdin_buffer[STDIN_BUFFER_SIZE];
 static LinuxFile StdIn(0, stdin_buffer, STDIN_BUFFER_SIZE, _IOFBF, false,
                        File::ModeFlags(File::OpenMode::READ));
 File *stdin = &StdIn;
 
 constexpr size_t STDOUT_BUFFER_SIZE = 1024;
 char stdout_buffer[STDOUT_BUFFER_SIZE];

libc/src/stdio/CMakeLists.txt

add_entrypoint_object(
   DEPENDS
     libc.src.__support.File.file
     libc.src.__support.File.platform_file
     libc.src.__support.arg_list
     libc.src.stdio.printf_core.vfprintf_internal
 )
 
 add_entrypoint_object(
+  ftell
+  ALIAS
+  DEPENDS
+    .${LIBC_TARGET_OS}.ftell
+)
+
+add_entrypoint_object(
+  ftello
+  ALIAS
+  DEPENDS
+    .${LIBC_TARGET_OS}.ftello
+)
+
+add_entrypoint_object(
   remove
   ALIAS
   DEPENDS
     .${LIBC_TARGET_OS}.remove
 )

libc/src/stdio/ftell.h

+//===-- Implementation header of ftell --------------------------*- 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_FTELL_H
+#define LLVM_LIBC_SRC_STDIO_FTELL_H
+
+#include <stdio.h>
+
+namespace __llvm_libc {
+
+long ftell(::FILE *f);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_STDIO_FTELL_H

libc/src/stdio/ftello.h

+//===-- 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 __llvm_libc {
+
+off_t ftello(::FILE *f);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_STDIO_FTELLO_H

libc/src/stdio/linux/CMakeLists.txt

 add_entrypoint_object(
   remove
   SRCS
     remove.cpp
   HDRS
     ../remove.h
   DEPENDS
     libc.include.fcntl
     libc.include.unistd
     libc.include.sys_syscall
     libc.src.__support.OSUtil.osutil
     libc.src.errno.errno
 )
+
+add_header_library(
+  ftell_operation
+  HDRS
+    ftell_operation.h
+  DEPENDS
+    libc.include.stdio
+    libc.include.sys_syscall
+    libc.src.__support.File.file
+    libc.src.errno.errno
+)
+
+add_entrypoint_object(
+  ftell
+  SRCS
+    ftell.cpp
+  HDRS
+    ../ftell.h
+  DEPENDS
+    libc.include.stdio
+    libc.src.__support.OSUtil.osutil
+    libc.src.__support.File.file
+    libc.src.__support.File.platform_file
+)
+
+add_entrypoint_object(
+  ftello
+  SRCS
+    ftello.cpp
+  HDRS
+    ../ftello.h
+  DEPENDS
+    libc.include.stdio
+    libc.src.__support.OSUtil.osutil
+    libc.src.__support.File.file
+    libc.src.__support.File.platform_file
+)

libc/src/stdio/linux/ftell.cpp

+//===-- Implementation of ftell -------------------------------------------===//
+//
+// 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/ftell.h"
+#include "ftell_operation.h"
+
+#include <stdio.h>
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(long, ftell, (::FILE * stream)) {
+  return ftell_operation(stream);
+}
+
+} // namespace __llvm_libc

libc/src/stdio/linux/ftell_operation.h

+//===-- Implementation of linux ftell operation ---------------------------===//
+//
+// 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/__support/File/file.h"
+
+#include <errno.h>
+#include <stdio.h>
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace __llvm_libc {
+
+// An implementation of ftell to be used by the C standard ftell and POSIX
+// ftello functions.
+inline long ftell_operation(FILE *stream) {
+  File *file = reinterpret_cast<__llvm_libc::File *>(stream);
+  int fd = __llvm_libc::get_fileno(file);
+  int whence = SEEK_CUR;
+  if (file->iseof())
+    whence = SEEK_END;
+  long result;
+#ifdef SYS_lseek
+  long ret = __llvm_libc::syscall_impl(SYS_lseek, fd, 0, whence);
+  result = ret;
+#elif defined(SYS__llseek)
+  long ret = __llvm_libc::syscall_impl(SYS__llseek, fd, 0, 0, &result, whence);
+#else
+#error "lseek and _llseek syscalls not available."
+#endif
+
+  if (ret < 0) {
+    errno = -ret;
+    return -1;
+  }
+  return result;
+}
+
+} // namespace __llvm_libc

libc/src/stdio/linux/ftello.cpp

+//===-- 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 "ftell_operation.h"
+
+#include <stdio.h>
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(long, ftello, (::FILE * stream)) {
+  return ftell_operation(stream);
+}
+
+} // namespace __llvm_libc

libc/test/src/stdio/CMakeLists.txt

DEPENDS
     libc.src.stdio.fclose
     libc.src.stdio.feof
     libc.src.stdio.ferror
     libc.src.stdio.fgets
     libc.src.stdio.fopen
     libc.src.stdio.fwrite
 )
 
+add_libc_unittest(
+  ftell_test
+  SUITE
+    libc_stdio_unittests
+  SRCS
+    ftell_test.cpp
+  DEPENDS
+    libc.include.errno
+    libc.include.stdio
+    libc.src.stdio.fclose
+    libc.src.stdio.fflush
+    libc.src.stdio.fopen
+    libc.src.stdio.fseek
+    libc.src.stdio.ftell
+    libc.src.stdio.fwrite
+)
+
+add_libc_unittest(
+  ftello_test
+  SUITE
+    libc_stdio_unittests
+  SRCS
+    ftello_test.cpp
+  DEPENDS
+    libc.include.errno
+    libc.include.stdio
+    libc.src.stdio.fclose
+    libc.src.stdio.fflush
+    libc.src.stdio.fopen
+    libc.src.stdio.fseek
+    libc.src.stdio.ftello
+    libc.src.stdio.fwrite
+)
+
 add_subdirectory(printf_core)
 add_subdirectory(scanf_core)
 add_subdirectory(testdata)

libc/test/src/stdio/ftell_test.cpp

+//===-- Unittests for ftell -----------------------------------------------===//
+//
+// 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/fclose.h"
+#include "src/stdio/fflush.h"
+#include "src/stdio/fopen.h"
+#include "src/stdio/fseek.h"
+#include "src/stdio/ftell.h"
+#include "src/stdio/fwrite.h"
+#include "utils/UnitTest/Test.h"
+
+#include <errno.h>
+#include <stdio.h>
+
+TEST(LlvmLibcFtellTest, WriteAndTell) {
+  constexpr char FILENAME[] = "testdata/ftell.test";
+  ::FILE *file = __llvm_libc::fopen(FILENAME, "w");
+  ASSERT_FALSE(file == nullptr);
+  constexpr char CONTENT[] = "123456789";
+  constexpr size_t WRITE_SIZE = sizeof(CONTENT) - 1;
+  ASSERT_EQ(WRITE_SIZE, __llvm_libc::fwrite(CONTENT, 1, WRITE_SIZE, file));
+  ASSERT_EQ(0, __llvm_libc::fflush(file));
+
+  ASSERT_EQ(size_t(__llvm_libc::ftell(file)), WRITE_SIZE);
+
+  long offset = 5;
+  ASSERT_EQ(0, __llvm_libc::fseek(file, offset, SEEK_SET));
+  ASSERT_EQ(__llvm_libc::ftell(file), offset);
+  ASSERT_EQ(0, __llvm_libc::fseek(file, -offset, SEEK_END));
+  ASSERT_EQ(size_t(__llvm_libc::ftell(file)), size_t(WRITE_SIZE - offset));
+
+  ASSERT_EQ(0, __llvm_libc::fclose(file));
+}

libc/test/src/stdio/ftello_test.cpp

+//===-- Unittests for 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/fclose.h"
+#include "src/stdio/fflush.h"
+#include "src/stdio/fopen.h"
+#include "src/stdio/fseek.h"
+#include "src/stdio/ftello.h"
+#include "src/stdio/fwrite.h"
+#include "utils/UnitTest/Test.h"
+
+#include <errno.h>
+#include <stdio.h>
+
+TEST(LlvmLibcFtelloTest, WriteAndTell) {
+  constexpr char FILENAME[] = "testdata/ftello.test";
+  ::FILE *file = __llvm_libc::fopen(FILENAME, "w");
+  ASSERT_FALSE(file == nullptr);
+  constexpr char CONTENT[] = "123456789";
+  constexpr size_t WRITE_SIZE = sizeof(CONTENT) - 1;
+  ASSERT_EQ(WRITE_SIZE, __llvm_libc::fwrite(CONTENT, 1, WRITE_SIZE, file));
+  ASSERT_EQ(0, __llvm_libc::fflush(file));
+
+  ASSERT_EQ(size_t(__llvm_libc::ftello(file)), WRITE_SIZE);
+
+  long offset = 5;
+  ASSERT_EQ(0, __llvm_libc::fseek(file, offset, SEEK_SET));
+  ASSERT_EQ(__llvm_libc::ftello(file), off_t(offset));
+  ASSERT_EQ(0, __llvm_libc::fseek(file, -offset, SEEK_END));
+  ASSERT_EQ(__llvm_libc::ftello(file), off_t(WRITE_SIZE - offset));
+
+  ASSERT_EQ(0, __llvm_libc::fclose(file));
+}