AtomicFile: Add size() and remove() methods

Signed-off-by: Shaun Ruffell <sruffell@sruffell.net>

src/AtomicFile.cpp

@@ -26,6 +26,8 @@
 
 #include <csignal>
 #include <stdio.h>
+#include <string.h>
+#include <errno.h>
 #include <cassert>
 #include <iostream>
 #include <vector>
@@ -59,7 +61,9 @@ struct AtomicFile::impl
 
   bool open ();
   void close ();
+  size_t size () const;
   void truncate ();
+  void remove ();
   void read (std::string& content);
   void read (std::vector <std::string>& lines);
   void append (const std::string& content);
@@ -150,6 +154,18 @@ void AtomicFile::impl::close ()
   }
 }
 
+////////////////////////////////////////////////////////////////////////////////
+size_t AtomicFile::impl::size () const
+{
+  struct stat s;
+  const char *filename = (is_temp_active) ? temp_file._data.c_str () : real_file._data.c_str ();
+  if (stat (filename, &s))
+  {
+    throw format ("stat error {1}: {2}", errno, strerror (errno));
+  }
+  return s.st_size;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 void AtomicFile::impl::truncate ()
 {
@@ -165,6 +181,21 @@ void AtomicFile::impl::truncate ()
   }
 }
 
+////////////////////////////////////////////////////////////////////////////////
+void AtomicFile::impl::remove ()
+{
+  try
+  {
+    temp_file.remove ();
+    is_temp_active = true;
+  }
+  catch (...)
+  {
+    allow_atomics = false;
+    throw;
+  }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 void AtomicFile::impl::read (std::string& content)
 {
@@ -233,11 +264,19 @@ void AtomicFile::impl::finalize ()
 {
   if (is_temp_active && impl::allow_atomics)
   {
-    debug (format ("Moving '{1}' -> '{2}'", temp_file._data, real_file._data));
-    if (std::rename (temp_file._data.c_str (), real_file._data.c_str ()))
+    if (temp_file.exists ())
     {
-      throw format("Failed copying '{1}' to '{2}'. Database corruption possible.",
-                   temp_file._data, real_file._data);
+      debug (format ("Moving '{1}' -> '{2}'", temp_file._data, real_file._data));
+      if (std::rename (temp_file._data.c_str (), real_file._data.c_str ()))
+      {
+        throw format("Failed copying '{1}' to '{2}'. Database corruption possible.",
+            temp_file._data, real_file._data);
+      }
+    }
+    else
+    {
+      debug (format ("Removing '{1}'", real_file._data));
+      std::remove (real_file._data.c_str ());
     }
     is_temp_active = false;
   }
@@ -322,12 +361,24 @@ void AtomicFile::close ()
   pimpl->close ();
 }
 
+////////////////////////////////////////////////////////////////////////////////
+size_t AtomicFile::size () const
+{
+  return pimpl->size ();
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 void AtomicFile::truncate ()
 {
   pimpl->truncate ();
 }
 
+////////////////////////////////////////////////////////////////////////////////
+void AtomicFile::remove ()
+{
+  pimpl->remove ();
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 void AtomicFile::read (std::string& content)
 {

src/AtomicFile.h

@@ -48,7 +48,9 @@ public:
 
   bool open ();
   void close ();
+  void remove ();
   void truncate ();
+  size_t size () const;
   void read (std::string& content);
   void read (std::vector <std::string>& lines);
   void append (const std::string& content);

test/AtomicFileTest.cpp

@@ -24,6 +24,7 @@
 //
 ////////////////////////////////////////////////////////////////////////////////
 
+#include <cassert>
 #include <sstream>
 #include <memory>
 #include <string>
@@ -451,18 +452,27 @@ int test (UnitTest& t)
     t.fail (test_name);
     t.diag (std::string ("Expected '" + expected + "' read '" + contents + "'"));
   }
+  AtomicFile::reset ();
 
   {
-    AtomicFile test ("test");
+    tempDir.clear ();
+    Path test("test");
+    AtomicFile file(test);
+    file.truncate ();
+    assert (! test.exists ());
+    AtomicFile::finalize_all ();
+    assert (test.exists ());
+    file.remove ();
+    t.is (test.exists (), true, "File not removed before finalize");
+    AtomicFile::finalize_all ();
+    t.is (test.exists (), false, "File is removed after finalize");
   }
-
-  AtomicFile::reset ();
   return 0;
 }
 
 int main (int, char**)
 {
-  UnitTest t (20);
+  UnitTest t (22);
   try
   {
     int ret = test (t);