Get rid of C++ modules related code and rename *.mxx files to *.hxx

1 files changed, 0 insertions, 941 deletions

diff --git a/libbutl/fdstream.mxx b/libbutl/fdstream.mxx
deleted file mode 100644
index 0d3fd86..0000000
--- a/libbutl/fdstream.mxx
+++ /dev/null
@@ -1,941 +0,0 @@
-// file      : libbutl/fdstream.mxx -*- C++ -*-
-// license   : MIT; see accompanying LICENSE file
-
-#ifndef __cpp_modules_ts
-#pragma once
-#endif
-
-#include <cassert>
-
-#ifndef __cpp_lib_modules_ts
-#include <ios>     // streamsize
-#include <vector>
-#include <string>
-#include <chrono>
-#include <istream>
-#include <ostream>
-#include <utility> // move(), pair
-#include <cstdint> // uint16_t, uint64_t
-#include <cstddef> // size_t
-
-#include <iterator>
-#endif
-
-// Other includes.
-
-#ifdef __cpp_modules_ts
-export module butl.fdstream;
-#ifdef __cpp_lib_modules_ts
-import std.core;
-import std.io;
-#endif
-import butl.path;
-import butl.filesystem; // permissions, entry_stat
-import butl.small_vector;
-#else
-#include <libbutl/path.mxx>
-#include <libbutl/filesystem.mxx>
-#include <libbutl/small-vector.mxx>
-#include <libbutl/bufstreambuf.hxx>
-#endif
-
-#include <libbutl/export.hxx>
-
-LIBBUTL_MODEXPORT namespace butl
-{
-  // RAII type for file descriptors. Note that failure to close the descriptor
-  // is silently ignored by both the destructor and reset().
-  //
-  // The descriptor can be negative. Such a descriptor is treated as unopened
-  // and is not closed.
-  //
-  struct nullfd_t
-  {
-    constexpr explicit nullfd_t (int) {}
-    constexpr operator int () const {return -1;}
-  };
-
-#if defined(__cpp_modules_ts) && defined(__clang__) //@@ MOD Clang duplicate sym.
-  inline
-#endif
-  constexpr nullfd_t nullfd (-1);
-
-  class LIBBUTL_SYMEXPORT auto_fd
-  {
-  public:
-    auto_fd (nullfd_t = nullfd) noexcept: fd_ (-1) {}
-
-    explicit
-    auto_fd (int fd) noexcept: fd_ (fd) {}
-
-    auto_fd (auto_fd&& fd) noexcept: fd_ (fd.release ()) {}
-    auto_fd& operator= (auto_fd&&) noexcept;
-
-    auto_fd (const auto_fd&) = delete;
-    auto_fd& operator= (const auto_fd&) = delete;
-
-    ~auto_fd () noexcept;
-
-    int
-    get () const noexcept {return fd_;}
-
-    void
-    reset (int fd = -1) noexcept;
-
-    int
-    release () noexcept
-    {
-      int r (fd_);
-      fd_ = -1;
-      return r;
-    }
-
-    // Close an open file descriptor. Throw ios::failure on the underlying OS
-    // error. Reset the descriptor to -1 whether the exception is thrown or
-    // not.
-    //
-    void
-    close ();
-
-  private:
-    int fd_;
-  };
-
-  inline bool
-  operator== (const auto_fd& x, const auto_fd& y)
-  {
-    return x.get () == y.get ();
-  }
-
-  inline bool
-  operator!= (const auto_fd& x, const auto_fd& y)
-  {
-    return !(x == y);
-  }
-
-  inline bool
-  operator== (const auto_fd& x, nullfd_t)
-  {
-    return x.get () == -1;
-  }
-
-  inline bool
-  operator!= (const auto_fd& x, nullfd_t y)
-  {
-    return !(x == y);
-  }
-
-  // An [io]fstream that can be initialized with a file descriptor in addition
-  // to a file name and that also by default enables exceptions on badbit and
-  // failbit. So instead of a dance like this:
-  //
-  // ifstream ifs;
-  // ifs.exceptions (ifstream::badbit | ifstream::failbit);
-  // ifs.open (path.string ());
-  //
-  // You can simply do:
-  //
-  // ifdstream ifs (path);
-  //
-  // Notes and limitations:
-  //
-  // - char only
-  // - input or output but not both (can use a union of two streams for that)
-  // - no support for put back
-  // - use of tell[gp]() and seek[gp]() is discouraged on Windows for
-  //   fdstreams opened in the text mode (see fdstreambuf::seekoff()
-  //   implementation for reasoning and consider using non-standard tellg()
-  //   and seekg() in fdstreambuf, instead)
-  // - non-blocking file descriptor is supported only by showmanyc() function
-  //   and only for pipes on Windows, in contrast to POSIX systems
-  // - throws ios::failure in case of open(), read(), write(), close(),
-  //   seek[gp](), or tell[gp]() errors
-  // - exception mask has at least badbit
-  // - after catching an exception caused by badbit the stream is no longer
-  //   usable
-  // - not movable, though can be easily supported (or not: there is no move
-  //   constructor for istream/ostream in GCC 4.9)
-  // - passing to constructor auto_fd with a negative file descriptor is valid
-  //   and results in the creation of an unopened object
-  //
-  class LIBBUTL_SYMEXPORT fdstreambuf: public bufstreambuf
-  {
-  public:
-    fdstreambuf () = default;
-
-    // Unless specified, the current read/write position is assumed to
-    // be 0 (note: not queried).
-    //
-    fdstreambuf (auto_fd&&, std::uint64_t pos = 0);
-
-    // Before we invented auto_fd into fdstreams we keept fdstreambuf opened
-    // on faulty close attempt. Now fdstreambuf is always closed by close()
-    // function.  This semantics change seems to be the right one as there is
-    // no reason to expect fdclose() to succeed after it has already failed
-    // once.
-    //
-    void
-    close () {fd_.close ();}
-
-    auto_fd
-    release ();
-
-    void
-    open (auto_fd&&, std::uint64_t pos = 0);
-
-    bool
-    is_open () const {return fd_.get () >= 0;}
-
-    int
-    fd () const {return fd_.get ();}
-
-    // Set the file descriptor blocking mode returning the previous mode on
-    // success and throwing ios::failure otherwise (see fdmode() for details).
-    //
-    // Note that besides calling fdmode(fd()), this function also updating its
-    // internal state according to the new mode.
-    //
-    bool
-    blocking (bool);
-
-  public:
-    using base = bufstreambuf;
-
-    // basic_streambuf input interface.
-    //
-  public:
-    virtual std::streamsize
-    showmanyc ();
-
-    virtual int_type
-    underflow ();
-
-    // Direct access to the get area. Use with caution.
-    //
-    using base::gptr;
-    using base::egptr;
-    using base::gbump;
-
-    // Return the (logical) position of the next byte to be read.
-    //
-    using base::tellg;
-
-    // Seek to the (logical) position as if by reading the specified number of
-    // bytes from the beginning of the stream. Throw ios::failure on the
-    // underlying OS errors.
-    //
-    void
-    seekg (std::uint64_t);
-
-  private:
-    bool
-    load ();
-
-    // basic_streambuf output interface.
-    //
-  public:
-    virtual int_type
-    overflow (int_type);
-
-    virtual int
-    sync ();
-
-    virtual std::streamsize
-    xsputn (const char_type*, std::streamsize);
-
-    // Return the (logical) position of the next byte to be written.
-    //
-    using base::tellp;
-
-    // basic_streambuf positioning interface (both input/output).
-    //
-  public:
-    virtual pos_type
-    seekpos (pos_type, std::ios_base::openmode);
-
-    virtual pos_type
-    seekoff (off_type, std::ios_base::seekdir, std::ios_base::openmode);
-
-  private:
-    bool
-    save ();
-
-  private:
-    auto_fd fd_;
-    char buf_[8192];
-    bool non_blocking_ = false;
-  };
-
-  // File stream mode.
-  //
-  // The text/binary flags have the same semantics as those in std::fstream.
-  // Specifically, this is a noop for POSIX systems where the two modes are
-  // the same. On Windows, when reading in the text mode the sequence of 0xD,
-  // 0xA characters is translated into the single OxA character and 0x1A is
-  // interpreted as EOF. When writing in the text mode the OxA character is
-  // translated into the 0xD, 0xA sequence.
-  //
-  // The skip flag instructs the stream to skip to the end before closing the
-  // file descriptor. This is primarily useful when working with pipes where
-  // you may want not to "offend" the other end by closing your end before
-  // reading all the data.
-  //
-  // The blocking/non_blocking flags determine whether the IO operation should
-  // block or return control if currently there is no data to read or no room
-  // to write. Only the istream::readsome() function supports the semantics of
-  // non-blocking operations. In contrast to POSIX systems, we only support
-  // this for pipes on Windows, always assuming the blocking mode for other
-  // file descriptors. IO stream operations other than readsome() are illegal
-  // in the non-blocking mode and result in the badbit being set (note that
-  // it is not the more appropriate failbit for implementation reasons).
-  //
-  enum class fdstream_mode: std::uint16_t
-  {
-    text         = 0x01,
-    binary       = 0x02,
-    skip         = 0x04,
-    blocking     = 0x08,
-    non_blocking = 0x10
-  };
-
-  inline fdstream_mode operator& (fdstream_mode, fdstream_mode);
-  inline fdstream_mode operator| (fdstream_mode, fdstream_mode);
-  inline fdstream_mode operator&= (fdstream_mode&, fdstream_mode);
-  inline fdstream_mode operator|= (fdstream_mode&, fdstream_mode);
-
-  // Extended (compared to ios::openmode) file open flags.
-  //
-  enum class fdopen_mode: std::uint16_t
-  {
-    in         = 0x01, // Open for reading.
-    out        = 0x02, // Open for writing.
-    append     = 0x04, // Seek to the end of file before each write.
-    truncate   = 0x08, // Discard the file contents on open.
-    create     = 0x10, // Create a file if not exists.
-    exclusive  = 0x20, // Fail if the file exists and the create flag is set.
-    binary     = 0x40, // Set binary translation mode.
-    at_end     = 0x80, // Seek to the end of stream immediately after open.
-
-    none = 0           // Usefull when building the mode incrementally.
-  };
-
-  inline fdopen_mode operator& (fdopen_mode, fdopen_mode);
-  inline fdopen_mode operator| (fdopen_mode, fdopen_mode);
-  inline fdopen_mode operator&= (fdopen_mode&, fdopen_mode);
-  inline fdopen_mode operator|= (fdopen_mode&, fdopen_mode);
-
-  class LIBBUTL_SYMEXPORT fdstream_base
-  {
-  protected:
-    fdstream_base () = default;
-    fdstream_base (auto_fd&&, std::uint64_t pos);
-    fdstream_base (auto_fd&&, fdstream_mode, std::uint64_t pos);
-
-  public:
-    int
-    fd () const {return buf_.fd ();}
-
-  protected:
-    fdstreambuf buf_;
-  };
-
-  // iofdstream constructors and open() functions that take openmode as an
-  // argument mimic the corresponding iofstream functions in terms of the
-  // openmode mask interpretation. They throw std::invalid_argument for an
-  // invalid combination of flags (as per the standard). Note that the in and
-  // out flags are always added implicitly for ifdstream and ofdstream,
-  // respectively.
-  //
-  // iofdstream constructors and open() functions that take fdopen_mode as an
-  // argument interpret the mask literally just ignoring some flags which are
-  // meaningless in the absense of others (read more on that in the comment
-  // for fdopen()). Note that the in and out flags are always added implicitly
-  // for ifdstream and ofdstream, respectively.
-  //
-  // iofdstream constructors and open() functions that take file path as a
-  // const std::string& or const char* may throw the invalid_path exception.
-  //
-  // Passing auto_fd with a negative file descriptor is valid and results in
-  // the creation of an unopened object.
-  //
-  // Also note that open() and close() functions can be successfully called
-  // for an opened and unopened objects respectively. That is in contrast with
-  // iofstream that sets failbit in such cases.
-  //
-
-  // Note that ifdstream destructor will close an open file descriptor but
-  // will ignore any errors. To detect such errors, call close() explicitly.
-  //
-  // This is a sample usage of iofdstreams with process. Note that here it is
-  // expected that the child process reads from STDIN first and writes to
-  // STDOUT afterwards.
-  //
-  // try
-  // {
-  //   process pr (args, -1, -1);
-  //
-  //   try
-  //   {
-  //     // In case of exception, skip and close input after output.
-  //     //
-  //     ifdstream is (move (pr.in_ofd), fdstream_mode::skip);
-  //     ofdstream os (move (pr.out_fd));
-  //
-  //     // Write.
-  //
-  //     os.close (); // Don't block the other end.
-  //
-  //     // Read.
-  //
-  //     is.close (); // Skip till end and close.
-  //
-  //     if (pr.wait ())
-  //     {
-  //       return ...; // Good.
-  //     }
-  //
-  //     // Non-zero exit, diagnostics presumably issued, fall through.
-  //   }
-  //   catch (const failure&)
-  //   {
-  //     // IO failure, child exit status doesn't matter. Just wait for the
-  //     // process completion and fall through.
-  //     //
-  //     // Note that this is optional if the process_error handler simply
-  //     // falls through since process destructor will wait (but will ignore
-  //     // any errors).
-  //     //
-  //     pr.wait ();
-  //   }
-  //
-  //   error <<  .... ;
-  //
-  //   // Fall through.
-  // }
-  // catch (const process_error& e)
-  // {
-  //   error << ... << e;
-  //
-  //   if (e.child ())
-  //     exit (1);
-  //
-  //   // Fall through.
-  // }
-  //
-  // throw failed ();
-  //
-  class LIBBUTL_SYMEXPORT ifdstream: public fdstream_base, public std::istream
-  {
-  public:
-    // Create an unopened object.
-    //
-    explicit
-    ifdstream (iostate = badbit | failbit);
-
-    explicit
-    ifdstream (auto_fd&&,
-               iostate = badbit | failbit,
-               std::uint64_t pos = 0);
-
-    ifdstream (auto_fd&&,
-               fdstream_mode m,
-               iostate = badbit | failbit,
-               std::uint64_t pos = 0);
-
-    explicit
-    ifdstream (const char*,
-               iostate = badbit | failbit);
-
-    explicit
-    ifdstream (const std::string&,
-               iostate = badbit | failbit);
-
-    explicit
-    ifdstream (const path&,
-               iostate = badbit | failbit);
-
-    // @@ In some implementations (for example, MSVC), iostate and openmode
-    //    (and/or their respective constants) are not distinct enough which
-    //    causes overload resolution errors.
-    //
-    ifdstream (const char*,
-               openmode,
-               iostate /*= badbit | failbit*/);
-
-    ifdstream (const std::string&,
-               openmode,
-               iostate /*= badbit | failbit*/);
-
-    ifdstream (const path&,
-               openmode,
-               iostate /*= badbit | failbit*/);
-
-    ifdstream (const char*,
-               fdopen_mode,
-               iostate = badbit | failbit);
-
-    ifdstream (const std::string&,
-               fdopen_mode,
-               iostate = badbit | failbit);
-
-    ifdstream (const path&,
-               fdopen_mode,
-               iostate = badbit | failbit);
-
-    ~ifdstream () override;
-
-    void
-    open (const char*, openmode = in);
-
-    void
-    open (const std::string&, openmode = in);
-
-    void
-    open (const path&, openmode = in);
-
-    void
-    open (const char*, fdopen_mode);
-
-    void
-    open (const std::string&, fdopen_mode);
-
-    void
-    open (const path&, fdopen_mode);
-
-    void
-    open (auto_fd&& fd, std::uint64_t pos = 0)
-    {
-      buf_.open (std::move (fd), pos);
-      clear ();
-    }
-
-    void
-    open (auto_fd&& fd, fdstream_mode m, std::uint64_t pos = 0);
-
-    void close ();
-    auto_fd release (); // Note: no skipping.
-    bool is_open () const {return buf_.is_open ();}
-
-    // Read the textual stream. The stream is supposed not to contain the null
-    // character.
-    //
-    std::string
-    read_text ();
-
-    // Read the binary stream.
-    //
-    std::vector<char>
-    read_binary ();
-
-  private:
-    bool skip_ = false;
-  };
-
-  // Note that ofdstream requires that you explicitly call close() before
-  // destroying it. Or, more specifically, the ofdstream object should not be
-  // in the opened state by the time its destructor is called, unless it is in
-  // the "not good" state (good() == false) or the destructor is being called
-  // during the stack unwinding due to an exception being thrown
-  // (std::uncaught_exception() == true). This is enforced with assert() in
-  // the ofdstream destructor.
-  //
-  class LIBBUTL_SYMEXPORT ofdstream: public fdstream_base, public std::ostream
-  {
-  public:
-    // Create an unopened object.
-    //
-    explicit
-    ofdstream (iostate = badbit | failbit);
-
-    explicit
-    ofdstream (auto_fd&&,
-               iostate = badbit | failbit,
-               std::uint64_t pos = 0);
-
-    ofdstream (auto_fd&&,
-               fdstream_mode m,
-               iostate = badbit | failbit,
-               std::uint64_t pos = 0);
-
-    explicit
-    ofdstream (const char*,
-               iostate = badbit | failbit);
-
-    explicit
-    ofdstream (const std::string&,
-               iostate = badbit | failbit);
-
-    explicit
-    ofdstream (const path&,
-               iostate = badbit | failbit);
-
-    // @@ In some implementations (for example, MSVC), iostate and openmode
-    //    (and/or their respective constants) are not distinct enough which
-    //    causes overload resolution errors.
-    //
-    ofdstream (const char*,
-               openmode,
-               iostate /*= badbit | failbit*/);
-
-    ofdstream (const std::string&,
-               openmode,
-               iostate /*= badbit | failbit*/);
-
-    ofdstream (const path&,
-               openmode,
-               iostate /*= badbit | failbit*/);
-
-    ofdstream (const char*,
-               fdopen_mode,
-               iostate = badbit | failbit);
-
-    ofdstream (const std::string&,
-               fdopen_mode,
-               iostate = badbit | failbit);
-
-    ofdstream (const path&,
-               fdopen_mode,
-               iostate = badbit | failbit);
-
-    ~ofdstream () override;
-
-    void
-    open (const char*, openmode = out);
-
-    void
-    open (const std::string&, openmode = out);
-
-    void
-    open (const path&, openmode = out);
-
-    void
-    open (const char*, fdopen_mode);
-
-    void
-    open (const std::string&, fdopen_mode);
-
-    void
-    open (const path&, fdopen_mode);
-
-    void
-    open (auto_fd&& fd, std::uint64_t pos = 0)
-    {
-      buf_.open (std::move (fd), pos);
-      clear ();
-    }
-
-    void close () {if (is_open ()) flush (); buf_.close ();}
-    auto_fd release ();
-    bool is_open () const {return buf_.is_open ();}
-  };
-
-  // Open a file or, if the file name is `-`, stdin/stdout.
-  //
-  // In case of the stdin/stdout, these functions simply adjust the exception
-  // mask on std::cin/cout to match the i/ofdstreams argument.
-  //
-  // Return a reference to the opened i/ofdstream or cin/cout and, in the
-  // latter case, set the translated name in path_name to <stdin>/<stdout>
-  // (unless it is already present).
-  //
-  // Note that ofdstream::close() should be called explicitly unless stdout
-  // was opened (but harmless to call even if it was).
-  //
-  LIBBUTL_SYMEXPORT std::istream&
-  open_file_or_stdin (path_name&, ifdstream&);
-
-  LIBBUTL_SYMEXPORT std::ostream&
-  open_file_or_stdout (path_name&, ofdstream&);
-
-  // The std::getline() replacement that provides a workaround for libstdc++'s
-  // ios::failure ABI fiasco (#66145) by throwing ios::failure, as it is
-  // defined at libbutl build time (new ABI on recent distributions) rather
-  // than libstdc++ build time (still old ABI on most distributions).
-  //
-  // Notes:
-  //
-  // - This relies of ADL so if the stream is used via the std::istream
-  //   interface, then std::getline() will still be used. To put it another
-  //   way, this is "the best we can do" until GCC folks get their act
-  //   together.
-  //
-  // - The fail and eof bits may be left cleared in the stream exception mask
-  //   when the function throws because of badbit.
-  //
-  LIBBUTL_SYMEXPORT ifdstream&
-  getline (ifdstream&, std::string&, char delim = '\n');
-
-  // Open a file returning an auto_fd that holds its file descriptor on
-  // success and throwing ios::failure otherwise.
-  //
-  // The mode argument should have at least one of the in or out flags set.
-  // The append and truncate flags are meaningless in the absense of the out
-  // flag and are ignored without it. The exclusive flag is meaningless in the
-  // absense of the create flag and is ignored without it. Note also that if
-  // the exclusive flag is specified then a dangling symbolic link is treated
-  // as an existing file.
-  //
-  // The permissions argument is taken into account only if the file is
-  // created. Note also that permissions can be adjusted while being set in a
-  // way specific for the OS. On POSIX systems they are modified with the
-  // process' umask, so effective permissions are permissions & ~umask. On
-  // Windows permissions other than ru and wu are unlikelly to have effect.
-  //
-  // Also note that on POSIX the FD_CLOEXEC flag is set for the file descriptor
-  // to prevent its leakage into child processes. On Windows, for the same
-  // purpose, the _O_NOINHERIT flag is set. Note that the process class, that
-  // passes such a descriptor to the child, makes it inheritable for a while.
-  //
-  LIBBUTL_SYMEXPORT auto_fd
-  fdopen (const char*,
-          fdopen_mode,
-          permissions = permissions::ru | permissions::wu |
-                        permissions::rg | permissions::wg |
-                        permissions::ro | permissions::wo);
-
-  LIBBUTL_SYMEXPORT auto_fd
-  fdopen (const std::string&,
-          fdopen_mode,
-          permissions = permissions::ru | permissions::wu |
-                        permissions::rg | permissions::wg |
-                        permissions::ro | permissions::wo);
-
-  LIBBUTL_SYMEXPORT auto_fd
-  fdopen (const path&,
-          fdopen_mode,
-          permissions = permissions::ru | permissions::wu |
-                        permissions::rg | permissions::wg |
-                        permissions::ro | permissions::wo);
-
-  // Duplicate an open file descriptor. Throw ios::failure on the underlying
-  // OS error.
-  //
-  // Note that on POSIX the FD_CLOEXEC flag is set for the new descriptor if it
-  // is present for the source one. That's in contrast to POSIX dup() that
-  // doesn't copy file descriptor flags. Also note that duplicating descriptor
-  // and setting the flag is not an atomic operation generally, but it is in
-  // regards to child process spawning (to prevent file descriptor leakage into
-  // a child process).
-  //
-  // Note that on Windows the _O_NOINHERIT flag is set for the new descriptor
-  // if it is present for the source one. That's in contrast to Windows _dup()
-  // that doesn't copy the flag. Also note that duplicating descriptor and
-  // setting the flag is not an atomic operation generally, but it is in
-  // regards to child process spawning (to prevent file descriptor leakage into
-  // a child process).
-  //
-  LIBBUTL_SYMEXPORT auto_fd
-  fddup (int fd);
-
-  // Set the translation and/or blocking modes for the file descriptor. Throw
-  // invalid_argument for an invalid combination of flags. Return the previous
-  // mode on success, throw ios::failure otherwise.
-  //
-  // The text and binary flags are mutually exclusive on Windows. On POSIX
-  // system the two modes are the same and so no check is performed.
-  //
-  // The blocking and non-blocking flags are mutually exclusive. In contrast
-  // to POSIX systems, on Windows the non-blocking mode is only supported for
-  // pipes, with the blocking mode assumed for other file descriptors
-  // regardless of the flags.
-  //
-  // Note that on Wine currently pipes always behave as blocking regardless of
-  // the mode set.
-  //
-  LIBBUTL_SYMEXPORT fdstream_mode
-  fdmode (int, fdstream_mode);
-
-  // Portable functions for obtaining file descriptors of standard streams.
-  // Throw ios::failure on the underlying OS error.
-  //
-  // Note that you normally wouldn't want to close them using fddup() to
-  // convert them to auto_fd, for example:
-  //
-  // ifdstream is (fddup (stdin_fd ()));
-  //
-  LIBBUTL_SYMEXPORT int stdin_fd  ();
-  LIBBUTL_SYMEXPORT int stdout_fd ();
-  LIBBUTL_SYMEXPORT int stderr_fd ();
-
-  // Convenience functions for setting the translation mode for standard
-  // streams.
-  //
-  LIBBUTL_SYMEXPORT fdstream_mode stdin_fdmode  (fdstream_mode);
-  LIBBUTL_SYMEXPORT fdstream_mode stdout_fdmode (fdstream_mode);
-  LIBBUTL_SYMEXPORT fdstream_mode stderr_fdmode (fdstream_mode);
-
-  // Low-level, nothrow file descriptor API.
-  //
-
-  // Close the file descriptor. Return true on success, set errno and return
-  // false otherwise.
-  //
-  LIBBUTL_SYMEXPORT bool
-  fdclose (int) noexcept;
-
-  // Open the null device (e.g., /dev/null) that discards all data written to
-  // it and provides no data for read operations (i.e., yelds EOF on read).
-  // Return an auto_fd that holds its file descriptor on success and throwing
-  // ios::failure otherwise.
-  //
-  // On Windows the null device is NUL and writing anything substantial to it
-  // (like redirecting a process' output) is extremely slow, as in, an order
-  // of magnitude slower than writing to disk. If you are using the descriptor
-  // yourself this can be mitigated by setting the binary mode (already done
-  // by fdopen()) and using a buffer of around 64K. However, sometimes you
-  // have no control of how the descriptor will be used. For instance, it can
-  // be used to redirect a child's stdout and the way the child sets up its
-  // stdout is out of your control (on Windows). For such cases, there is an
-  // emulation via a temporary file. Mostly it functions as a proper null
-  // device with the file automatically removed once the descriptor is
-  // closed. One difference, however, would be if you were to both write to
-  // and read from the descriptor.
-  //
-  // Note that on POSIX the FD_CLOEXEC flag is set for the file descriptor to
-  // prevent its leakage into child processes. On Windows, for the same
-  // purpose, the _O_NOINHERIT flag is set.
-  //
-#ifndef _WIN32
-  LIBBUTL_SYMEXPORT auto_fd
-  fdopen_null ();
-#else
-  LIBBUTL_SYMEXPORT auto_fd
-  fdopen_null (bool temp = false);
-#endif
-
-  struct fdpipe
-  {
-    auto_fd in;
-    auto_fd out;
-
-    void
-    close ()
-    {
-      in.close ();
-      out.close ();
-    }
-  };
-
-  // Create a pipe. Throw ios::failure on the underlying OS error. By default
-  // both ends of the pipe are opened in the text mode. Pass the binary flag
-  // to instead open them in the binary mode. Passing a mode other than none
-  // or binary is illegal.
-  //
-  // Note that on Windows both ends of the created pipe are not inheritable.
-  // In particular, the process class that uses fdpipe underneath makes the
-  // appropriate end (the one being passed to the child) inheritable.
-  //
-  // Note that on POSIX the FD_CLOEXEC flag is set for both ends, so they get
-  // automatically closed by the child process to prevent undesired behaviors
-  // (such as child deadlock on read from a pipe due to the write-end leakage
-  // into the child process). Opening a pipe and setting the flag is not an
-  // atomic operation generally, but it is in regards to child process spawning
-  // (to prevent file descriptor leakage into child processes spawned from
-  // other threads). Also note that you don't need to reset the flag for a pipe
-  // end being passed to the process class ctor.
-  //
-  LIBBUTL_SYMEXPORT fdpipe
-  fdopen_pipe (fdopen_mode = fdopen_mode::none);
-
-  // Seeking.
-  //
-  enum class fdseek_mode {set, cur, end};
-
-  LIBBUTL_SYMEXPORT std::uint64_t
-  fdseek (int, std::int64_t, fdseek_mode);
-
-  // Truncate or expand the file to the specified size. Throw ios::failure on
-  // the underlying OS error.
-  //
-  LIBBUTL_SYMEXPORT void
-  fdtruncate (int, std::uint64_t);
-
-  // Return filesystem entry stat from file descriptor. Throw ios::failure on
-  // the underlying OS error.
-  //
-  // See also path_entry() in filesystem.
-  //
-  LIBBUTL_SYMEXPORT entry_stat
-  fdstat (int);
-
-  // Test whether a file descriptor refers to a terminal. Throw ios::failure
-  // on the underlying OS error.
-  //
-  LIBBUTL_SYMEXPORT bool
-  fdterm (int);
-
-  // Wait until one or more file descriptors becomes ready for input (reading)
-  // or output (writing). Return the pair of numbers of descriptors that are
-  // ready. Throw std::invalid_argument if anything is wrong with arguments
-  // (both sets are empty, invalid fd, etc). Throw ios::failure on the
-  // underlying OS error.
-  //
-  // Note that the function clears all the previously-ready entries on each
-  // call. Entries with nullfd are ignored.
-  //
-  // On Windows only pipes and only their input (read) ends are supported.
-  //
-  struct fdselect_state
-  {
-    int  fd;
-    bool ready;
-
-    // Note: intentionally non-explicit to allow implicit initialization when
-    // pushing to fdselect_set.
-    //
-    fdselect_state (int fd): fd (fd), ready (false) {}
-  };
-
-  using fdselect_set = small_vector<fdselect_state, 4>;
-
-  LIBBUTL_SYMEXPORT std::pair<std::size_t, std::size_t>
-  fdselect (fdselect_set& ifds, fdselect_set& ofds);
-
-  inline std::size_t
-  ifdselect (fdselect_set& ifds)
-  {
-    fdselect_set ofds;
-    return fdselect (ifds, ofds).first;
-  }
-
-  inline std::size_t
-  ofdselect (fdselect_set& ofds)
-  {
-    fdselect_set ifds;
-    return fdselect (ifds, ofds).second;
-  }
-
-  // As above but wait up to the specified timeout returning a pair of zeroes
-  // if none of the descriptors became ready.
-  //
-  template <typename R, typename P>
-  std::pair<std::size_t, std::size_t>
-  fdselect (fdselect_set&, fdselect_set&, const std::chrono::duration<R, P>&);
-
-  template <typename R, typename P>
-  inline std::size_t
-  ifdselect (fdselect_set& ifds, const std::chrono::duration<R, P>& timeout)
-  {
-    fdselect_set ofds;
-    return fdselect (ifds, ofds, timeout).first;
-  }
-
-  template <typename R, typename P>
-  inline std::size_t
-  ofdselect (fdselect_set& ofds, const std::chrono::duration<R, P>& timeout)
-  {
-    fdselect_set ifds;
-    return fdselect (ifds, ofds, timeout).second;
-  }
-
-  // POSIX read() function wrapper. In particular, it supports the semantics
-  // of non-blocking read for pipes on Windows.
-  //
-  // Note that on Wine currently pipes always behave as blocking regardless of
-  // the mode.
-  //
-  LIBBUTL_SYMEXPORT std::streamsize
-  fdread (int, void*, std::size_t);
-}
-
-#include <libbutl/fdstream.ixx>