Add auto_fd::close()

2 files changed, 29 insertions, 5 deletions

diff --git a/butl/fdstream b/butl/fdstream
index 9c7274d..289d925 100644
--- a/butl/fdstream
+++ b/butl/fdstream
@@ -19,8 +19,7 @@
 namespace butl
 {
   // RAII type for file descriptors. Note that failure to close the descriptor
-  // is silently ignored by both the destructor and reset() (thought we could
-  // probably provide the close() function that throws).
+  // 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.
@@ -28,7 +27,7 @@ namespace butl
   struct nullfd_t {constexpr explicit nullfd_t (int) {}};
   constexpr const nullfd_t nullfd (-1);
 
-  class auto_fd
+  class LIBBUTL_EXPORT auto_fd
   {
   public:
     auto_fd (nullfd_t = nullfd): fd_ (-1) {}
@@ -53,6 +52,12 @@ namespace butl
     void
     reset (int fd = -1) noexcept;
 
+    // Close an open file descriptor. Throw ios::failure on failure. The object
+    // become unopened whenever the exception is thrown or not.
+    //
+    void
+    close ();
+
   private:
     int fd_;
   };
diff --git a/butl/fdstream.cxx b/butl/fdstream.cxx
index dbd7767..102ad66 100644
--- a/butl/fdstream.cxx
+++ b/butl/fdstream.cxx
@@ -68,6 +68,26 @@ namespace butl
       ec, m);
   }
 
+  // auto_fd
+  //
+  void auto_fd::
+  close ()
+  {
+    if (fd_ >= 0)
+    {
+      bool r (fdclose (fd_));
+
+      // If fdclose() failed then no reason to expect it to succeed the next
+      // time.
+      //
+      fd_ = -1;
+
+      if (!r)
+        throw_ios_failure (errno);
+    }
+  }
+
+
   // fdbuf
   //
   fdbuf::
@@ -105,8 +125,7 @@ namespace butl
     // 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.
     //
-    if (is_open () && !fdclose (fd_.release ()))
-      throw_ios_failure (errno);
+    fd_.close ();
   }
 
   streamsize fdbuf::