Implement ofdstream

1 files changed, 64 insertions, 4 deletions

diff --git a/butl/fdstream.cxx b/butl/fdstream.cxx
index 6d7532a..0386f49 100644
--- a/butl/fdstream.cxx
+++ b/butl/fdstream.cxx
@@ -5,9 +5,9 @@
 #include <butl/fdstream>
 
 #ifndef _WIN32
-#  include <unistd.h>    // close, read
+#  include <unistd.h>    // close(), read(), write()
 #else
-#  include <io.h>        // _close, _read
+#  include <io.h>        // _close(), _read(), _write()
 #endif
 
 #include <system_error>
@@ -20,9 +20,18 @@ namespace butl
   ~fdbuf () {close ();}
 
   void fdbuf::
+  open (int fd)
+  {
+    close ();
+    fd_ = fd;
+    setg (buf_, buf_, buf_);
+    setp (buf_, buf_ + sizeof (buf_) - 1); // Keep space for overflow's char.
+  }
+
+  void fdbuf::
   close ()
   {
-    if (fd_ != -1)
+    if (is_open ())
     {
 #ifndef _WIN32
       ::close (fd_);
@@ -42,7 +51,7 @@ namespace butl
   fdbuf::int_type fdbuf::
   underflow ()
   {
-    int_type r = traits_type::eof ();
+    int_type r (traits_type::eof ());
 
     if (is_open ())
     {
@@ -68,4 +77,55 @@ namespace butl
     setg (buf_, buf_, buf_ + n);
     return n != 0;
   }
+
+  fdbuf::int_type fdbuf::
+  overflow (int_type c)
+  {
+    int_type r (traits_type::eof ());
+
+    if (is_open () && c != traits_type::eof ())
+    {
+      // Store last character in the space we reserved in open(). Note
+      // that pbump() doesn't do any checks.
+      //
+      *pptr () = traits_type::to_char_type (c);
+      pbump (1);
+
+      if (save ())
+        r = c;
+    }
+
+    return r;
+  }
+
+  int fdbuf::
+  sync ()
+  {
+    return is_open () && save () ? 0 : -1;
+  }
+
+  bool fdbuf::
+  save ()
+  {
+    size_t n (pptr () - pbase ());
+
+    if (n != 0)
+    {
+#ifndef _WIN32
+      ssize_t m (::write (fd_, buf_, n));
+#else
+      int m (_write (fd_, buf_, static_cast<unsigned int> (sizeof (buf_))));
+#endif
+
+      if (m == -1)
+        throw system_error (errno, system_category ());
+
+      if (n != static_cast<size_t> (m))
+        return false;
+
+      setp (buf_, buf_ + sizeof (buf_) - 1);
+    }
+
+    return true;
+  }
 }