Add configfs, securityfs, cgroup and cgroup2 to blacklisted filesystems.

Use read/write loop for copying files from these filesystems, as they contain
generated content and have inaccurate file sizes.

Author: Lastique

doc/release_history.html

@@ -54,6 +54,7 @@ <h2>1.91.0</h2>
     </ul>
   </li>
   <li>On DragonFly BSD, NetBSD and Solaris, Boost.Filesystem default path locale now uses UTF-8 for path character encoding.</li>
+  <li>On Linux, use <code>read</code>/<code>write</code> loop implementation of <code>copy_file</code> and <code>copy</code> for configfs, securityfs, cgroup and cgroup2 filesystems, in addition to the previously blacklisted filesystems.</li>
 </ul>
 
 <h2>1.90.0</h2>

src/operations.cpp

@@ -984,6 +984,14 @@ int check_fs_type(int infile, int outfile, uintmax_t size, std::size_t blksize)
 
         if (BOOST_UNLIKELY(sfs.f_type == PROC_SUPER_MAGIC ||
             sfs.f_type == SYSFS_MAGIC ||
+#if defined(CGROUP2_SUPER_MAGIC)
+            sfs.f_type == CGROUP2_SUPER_MAGIC ||
+#endif
+#if defined(CGROUP_SUPER_MAGIC)
+            sfs.f_type == CGROUP_SUPER_MAGIC ||
+#endif
+            sfs.f_type == SECURITYFS_MAGIC ||
+            sfs.f_type == 0x62656570 || // CONFIGFS_MAGIC
             sfs.f_type == TRACEFS_MAGIC ||
             sfs.f_type == DEBUGFS_MAGIC))
         {