From 21acf9701d5f26ccc8c76775b0a3e1616e3b4ddd Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Mon, 24 Jul 2017 14:07:40 +0200
Subject: Add std*_fd() functions

---
 libbutl/fdstream.cxx | 36 ++++++++++++++++++------------------
 libbutl/fdstream.hxx | 10 ++++++++++
 libbutl/fdstream.ixx | 20 ++++++++++++++++++++
 3 files changed, 48 insertions(+), 18 deletions(-)

diff --git a/libbutl/fdstream.cxx b/libbutl/fdstream.cxx
index daa344f..7681c88 100644
--- a/libbutl/fdstream.cxx
+++ b/libbutl/fdstream.cxx
@@ -881,22 +881,22 @@ namespace butl
        : fdstream_mode::blocking);
   }
 
-  fdstream_mode
-  stdin_fdmode (fdstream_mode m)
+  int
+  stdin_fd ()
   {
-    return fdmode (STDIN_FILENO, m);
+    return STDIN_FILENO;
   }
 
-  fdstream_mode
-  stdout_fdmode (fdstream_mode m)
+  int
+  stdout_fd ()
   {
-    return fdmode (STDOUT_FILENO, m);
+    return STDOUT_FILENO;
   }
 
-  fdstream_mode
-  stderr_fdmode (fdstream_mode m)
+  int
+  stderr_fd ()
   {
-    return fdmode (STDERR_FILENO, m);
+    return STDERR_FILENO;
   }
 
   fdpipe
@@ -1064,34 +1064,34 @@ namespace butl
        : fdstream_mode::text);
   }
 
-  fdstream_mode
-  stdin_fdmode (fdstream_mode m)
+  int
+  stdin_fd ()
   {
     int fd (_fileno (stdin));
     if (fd == -1)
       throw_ios_failure (errno);
 
-    return fdmode (fd, m);
+    return fd;
   }
 
-  fdstream_mode
-  stdout_fdmode (fdstream_mode m)
+  int
+  stdout_fd ()
   {
     int fd (_fileno (stdout));
     if (fd == -1)
       throw_ios_failure (errno);
 
-    return fdmode (fd, m);
+    return fd;
   }
 
-  fdstream_mode
-  stderr_fdmode (fdstream_mode m)
+  int
+  stderr_fd ()
   {
     int fd (_fileno (stderr));
     if (fd == -1)
       throw_ios_failure (errno);
 
-    return fdmode (fd, m);
+    return fd;
   }
 
   fdpipe
diff --git a/libbutl/fdstream.hxx b/libbutl/fdstream.hxx
index 752f8ab..6673fed 100644
--- a/libbutl/fdstream.hxx
+++ b/libbutl/fdstream.hxx
@@ -595,6 +595,16 @@ namespace butl
   LIBBUTL_SYMEXPORT fdstream_mode
   fdmode (int, fdstream_mode);
 
+  // Portable functions for obtaining file descriptors of standard streams.
+  // 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.
   //
diff --git a/libbutl/fdstream.ixx b/libbutl/fdstream.ixx
index 5181903..212ec98 100644
--- a/libbutl/fdstream.ixx
+++ b/libbutl/fdstream.ixx
@@ -286,4 +286,24 @@ namespace butl
       static_cast<std::uint16_t> (x) |
       static_cast<std::uint16_t> (y));
   }
+
+  // std*_fdmode()
+  //
+  inline fdstream_mode
+  stdin_fdmode (fdstream_mode m)
+  {
+    return fdmode (stdin_fd (), m);
+  }
+
+  inline fdstream_mode
+  stdout_fdmode (fdstream_mode m)
+  {
+    return fdmode (stdout_fd (), m);
+  }
+
+  inline fdstream_mode
+  stderr_fdmode (fdstream_mode m)
+  {
+    return fdmode (stderr_fd (), m);
+  }
 }
-- 
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