platform specific code to deal with sete{u,g}id. closes #17

Makefile

@@ -74,6 +74,14 @@ $(warning "xattr not available: disabling")
 CFLAGS += -DWITHOUT_XATTR
 endif
 
+KERNEL = $(shell uname -s)
+ifeq ($(KERNEL),Linux)
+	CFLAGS += -DLINUX
+endif
+ifeq ($(KERNEL),Darwin)
+	CFLAGS += -DOSX
+endif
+
 all: $(TARGET)
 
 help:

src/access.cpp

@@ -70,8 +70,9 @@ namespace mergerfs
     access(const char *fusepath,
            int         mask)
     {
-      const ugid::SetResetGuard  ugid;
+      const struct fuse_context *fc     = fuse_get_context();
       const config::Config      &config = config::get();
+      const ugid::SetResetGuard  ugid(fc->uid,fc->gid);
 
       if(fusepath == config.controlfile)
         return _access(*config.search,

src/chmod.cpp

@@ -73,8 +73,9 @@ namespace mergerfs
     chmod(const char *fusepath,
           mode_t      mode)
     {
-      ugid::SetResetGuard   ugid;
-      const config::Config &config = config::get();
+      const struct fuse_context *fc     = fuse_get_context();
+      const ugid::SetResetGuard  ugid(fc->uid,fc->gid);
+      const config::Config      &config = config::get();
 
       if(fusepath == config.controlfile)
         return -EPERM;

src/chown.cpp

@@ -76,8 +76,9 @@ namespace mergerfs
           uid_t       uid,
           gid_t       gid)
     {
-      const ugid::SetResetGuard  ugid;
+      const struct fuse_context *fc     = fuse_get_context();
       const config::Config      &config = config::get();
+      const ugid::SetResetGuard  ugid(fc->uid,fc->gid);
 
       if(fusepath == config.controlfile)
         return -EPERM;

src/create.cpp

@@ -100,8 +100,9 @@ namespace mergerfs
            mode_t                 mode,
            struct fuse_file_info *fileinfo)
     {
-      ugid::SetResetGuard   ugid;
-      const config::Config &config = config::get();
+      const struct fuse_context *fc     = fuse_get_context();
+      const config::Config      &config = config::get();
+      const ugid::SetResetGuard  ugid(fc->uid,fc->gid);
 
       if(fusepath == config.controlfile)
         return _create_controlfile(fileinfo->fh);
@@ -110,7 +111,7 @@ namespace mergerfs
                      *config.create,
                      config.srcmounts,
                      fusepath,
-                     mode,
+                     (mode & ~fc->umask),
                      fileinfo->flags,
                      fileinfo->fh);
     }

src/fallocate.cpp

@@ -31,7 +31,6 @@
 #include <errno.h>
 #include <fcntl.h>
 
-#include "ugid.hpp"
 #include "config.hpp"
 #include "fileinfo.hpp"
 
@@ -77,9 +76,8 @@ namespace mergerfs
               off_t                  len,
               struct fuse_file_info *fi)
     {
-      const ugid::SetResetGuard  ugid;
-      const config::Config      &config   = config::get();
-      const FileInfo            *fileinfo = (FileInfo*)fi->fh;
+      const config::Config &config   = config::get();
+      const FileInfo       *fileinfo = (FileInfo*)fi->fh;
 
       if(fusepath == config.controlfile)
         return -EINVAL;

src/fgetattr.cpp

@@ -30,7 +30,6 @@
 #include <errno.h>
 
 #include "config.hpp"
-#include "ugid.hpp"
 #include "fileinfo.hpp"
 
 static
@@ -54,9 +53,8 @@ namespace mergerfs
              struct stat           *st,
              struct fuse_file_info *ffi)
     {
-      const ugid::SetResetGuard  ugid;
-      const config::Config      &config   = config::get();
-      const FileInfo            *fileinfo = (FileInfo*)ffi->fh;
+      const config::Config &config   = config::get();
+      const FileInfo       *fileinfo = (FileInfo*)ffi->fh;
 
       if(fusepath == config.controlfile)
         return (*st = config.controlfilestat,0);

src/flush.cpp

@@ -27,7 +27,6 @@
 #include <unistd.h>
 #include <errno.h>
 
-#include "ugid.hpp"
 #include "fileinfo.hpp"
 
 static
@@ -53,8 +52,6 @@ namespace mergerfs
     flush(const char            *path,
           struct fuse_file_info *fi)
     {
-      const ugid::SetResetGuard ugid;
-
       return _flush(((FileInfo*)fi->fh)->fd);
     }
   }

src/fsync.cpp

@@ -35,7 +35,6 @@
 #include <errno.h>
 
 #include "config.hpp"
-#include "ugid.hpp"
 #include "fileinfo.hpp"
 
 static
@@ -61,9 +60,8 @@ namespace mergerfs
           int                    isdatasync,
           struct fuse_file_info *fi)
     {
-      const ugid::SetResetGuard  ugid;
-      const config::Config      &config   = config::get();
-      const FileInfo            *fileinfo = (FileInfo*)fi->fh;
+      const config::Config &config   = config::get();
+      const FileInfo       *fileinfo = (FileInfo*)fi->fh;
 
       if(fusepath == config.controlfile)
         return 0;

src/ftruncate.cpp

@@ -29,7 +29,6 @@
 #include <errno.h>
 
 #include "config.hpp"
-#include "ugid.hpp"
 #include "fileinfo.hpp"
 
 static
@@ -53,9 +52,8 @@ namespace mergerfs
               off_t                  size,
               struct fuse_file_info *fi)
     {
-      const ugid::SetResetGuard  ugid;
-      const config::Config      &config   = config::get();
-      const FileInfo            *fileinfo = (FileInfo*)fi->fh;
+      const config::Config &config   = config::get();
+      const FileInfo       *fileinfo = (FileInfo*)fi->fh;
 
       if(fusepath == config.controlfile)
         return -EPERM;

src/getattr.cpp

@@ -68,8 +68,9 @@ namespace mergerfs
     getattr(const char  *fusepath,
             struct stat *buf)
     {
-      const ugid::SetResetGuard  ugid;
+      const struct fuse_context *fc     = fuse_get_context();
       const config::Config      &config = config::get();
+      const ugid::SetResetGuard  ugid(fc->uid,fc->gid);
 
       if(fusepath == config.controlfile)
         return (*buf = config.controlfilestat,0);

src/getxattr.cpp

@@ -22,6 +22,8 @@
    THE SOFTWARE.
 */
 
+#include <fuse.h>
+
 #include <string>
 #include <vector>
 
@@ -112,8 +114,9 @@ namespace mergerfs
              char       *buf,
              size_t      count)
     {
-      const ugid::SetResetGuard  ugid;
+      const struct fuse_context *fc     = fuse_get_context();
       const config::Config      &config = config::get();
+      const ugid::SetResetGuard  ugid(fc->uid,fc->gid);
 
       if(fusepath == config.controlfile)
         return _getxattr_controlfile(config,

src/ioctl.cpp

@@ -32,7 +32,6 @@
 
 #include "config.hpp"
 #include "fileinfo.hpp"
-#include "ugid.hpp"
 
 static
 int
@@ -86,9 +85,8 @@ namespace mergerfs
           unsigned int           flags,
           void                  *data)
     {
-      const ugid::SetResetGuard  ugid;
-      const config::Config      &config   = config::get();
-      const FileInfo            *fileinfo = (FileInfo*)fi->fh;
+      const config::Config &config   = config::get();
+      const FileInfo       *fileinfo = (FileInfo*)fi->fh;
 
       if(fusepath == config.controlfile)
         return -EINVAL;

src/link.cpp

@@ -22,6 +22,8 @@
    THE SOFTWARE.
 */
 
+#include <fuse.h>
+
 #include <string>
 #include <vector>
 
@@ -76,8 +78,9 @@ namespace mergerfs
     link(const char *from,
          const char *to)
     {
-      const ugid::SetResetGuard  ugid;
+      const struct fuse_context *fc     = fuse_get_context();
       const config::Config      &config = config::get();
+      const ugid::SetResetGuard  ugid(fc->uid,fc->gid);
 
       if(from == config.controlfile)
         return -EPERM;

src/listxattr.cpp

@@ -22,6 +22,8 @@
    THE SOFTWARE.
 */
 
+#include <fuse.h>
+
 #include <string>
 #include <vector>
 
@@ -101,8 +103,9 @@ namespace mergerfs
               char       *list,
               size_t      size)
     {
-      const ugid::SetResetGuard  ugid;
+      const struct fuse_context *fc = fuse_get_context();
       const config::Config      &config = config::get();
+      const ugid::SetResetGuard  ugid(fc->uid,fc->gid);
 
       if(fusepath == config.controlfile)
         return _listxattr_controlfile(list,

src/mkdir.cpp

@@ -82,8 +82,9 @@ namespace mergerfs
     mkdir(const char *fusepath,
           mode_t      mode)
     {
-      const ugid::SetResetGuard  ugid;
+      const struct fuse_context *fc     = fuse_get_context();
       const config::Config      &config = config::get();
+      const ugid::SetResetGuard  ugid(fc->uid,fc->gid);
 
       if(fusepath == config.controlfile)
         return -EEXIST;
@@ -92,7 +93,7 @@ namespace mergerfs
                     *config.create,
                     config.srcmounts,
                     fusepath,
-                    mode);
+                    (mode & ~fc->umask));
     }
   }
 }

src/mknod.cpp

@@ -60,7 +60,7 @@ _mknod(const fs::SearchFunc  searchFunc,
   if(fs::path_exists(srcmounts,fusepath))
     return -EEXIST;
 
-  dirname      = fs::dirname(fusepath);
+  dirname = fs::dirname(fusepath);
   searchFunc(srcmounts,dirname,existingpath);
   if(existingpath.empty())
     return -ENOENT;
@@ -85,8 +85,9 @@ namespace mergerfs
           mode_t      mode,
           dev_t       rdev)
     {
-      const ugid::SetResetGuard  ugid;
+      const struct fuse_context *fc     = fuse_get_context();
       const config::Config      &config = config::get();
+      const ugid::SetResetGuard  ugid(fc->uid,fc->gid);
 
       if(fusepath == config.controlfile)
         return -EEXIST;
@@ -95,7 +96,7 @@ namespace mergerfs
                     *config.create,
                     config.srcmounts,
                     fusepath,
-                    mode,
+                    (mode & ~fc->umask),
                     rdev);
     }
   }

src/open.cpp

@@ -83,8 +83,9 @@ namespace mergerfs
     open(const char            *fusepath,
          struct fuse_file_info *fileinfo)
     {
-      const ugid::SetResetGuard  ugid;
+      const struct fuse_context *fc     = fuse_get_context();
       const config::Config      &config = config::get();
+      const ugid::SetResetGuard  ugid(fc->uid,fc->gid);;
 
       if(fusepath == config.controlfile)
         return _open_controlfile(fileinfo->fh);

src/read.cpp

@@ -77,8 +77,7 @@ namespace mergerfs
          off_t                  offset,
          struct fuse_file_info *fi)
     {
-      const ugid::SetResetGuard  ugid;
-      const config::Config      &config = config::get();
+      const config::Config &config = config::get();
 
       if(fusepath == config.controlfile)
         return _read_controlfile(config.readstr,

src/read_buf.cpp

@@ -108,8 +108,7 @@ namespace mergerfs
              off_t                   offset,
              struct fuse_file_info  *fi)
     {
-      const ugid::SetResetGuard  ugid;
-      const config::Config      &config = config::get();
+      const config::Config &config = config::get();
 
       if(fusepath == config.controlfile)
         return _read_buf_controlfile(config.readstr,

src/readdir.cpp

@@ -122,8 +122,9 @@ namespace mergerfs
             off_t                  offset,
             struct fuse_file_info *fi)
     {
-      const ugid::SetResetGuard  ugid;
+      const struct fuse_context *fc     = fuse_get_context();
       const config::Config      &config = config::get();
+      const ugid::SetResetGuard  ugid(fc->uid,fc->gid);
 
       return _readdir(config.srcmounts,
                       fusepath,

src/readlink.cpp

@@ -72,8 +72,9 @@ namespace mergerfs
              char       *buf,
              size_t      size)
     {
-      const ugid::SetResetGuard  ugid;
+      const struct fuse_context *fc     = fuse_get_context();
       const config::Config      &config = config::get();
+      const ugid::SetResetGuard  ugid(fc->uid,fc->gid);
 
       if(fusepath == config.controlfile)
         return -EINVAL;

src/release.cpp

@@ -71,8 +71,7 @@ namespace mergerfs
     release(const char            *fusepath,
             struct fuse_file_info *fi)
     {
-      const ugid::SetResetGuard  ugid;
-      const config::Config      &config = config::get();
+      const config::Config &config = config::get();
 
       if(fusepath == config.controlfile)
         return _release_controlfile(fi->fh);

src/removexattr.cpp

@@ -22,6 +22,8 @@
    THE SOFTWARE.
 */
 
+#include <fuse.h>
+
 #include <string>
 #include <vector>
 
@@ -78,8 +80,9 @@ namespace mergerfs
     removexattr(const char *fusepath,
                 const char *attrname)
     {
-      const ugid::SetResetGuard  uid;
+      const struct fuse_context *fc     = fuse_get_context();
       const config::Config      &config = config::get();
+      const ugid::SetResetGuard  ugid(fc->uid,fc->gid);
 
       if(fusepath == config.controlfile)
         return -ENOTSUP;

src/rename.cpp

@@ -22,6 +22,8 @@
    THE SOFTWARE.
 */
 
+#include <fuse.h>
+
 #include <stdio.h>
 #include <errno.h>
 #include <unistd.h>
@@ -67,8 +69,9 @@ namespace mergerfs
     rename(const char *from,
            const char *to)
     {
-      const ugid::SetResetGuard  uid;
+      const struct fuse_context *fc     = fuse_get_context();
       const config::Config      &config = config::get();
+      const ugid::SetResetGuard  ugid(fc->uid,fc->gid);
 
       if(from == config.controlfile)
         return -ENOENT;

src/rmdir.cpp

@@ -22,6 +22,8 @@
    THE SOFTWARE.
 */
 
+#include <fuse.h>
+
 #include <errno.h>
 #include <unistd.h>
 
@@ -70,8 +72,9 @@ namespace mergerfs
     int
     rmdir(const char *fusepath)
     {
-      const ugid::SetResetGuard  uid;
+      const struct fuse_context *fc     = fuse_get_context();
       const config::Config      &config = config::get();
+      const ugid::SetResetGuard  ugid(fc->uid,fc->gid);
 
       if(fusepath == config.controlfile)
         return -ENOTDIR;

src/setxattr.cpp

@@ -22,6 +22,8 @@
    THE SOFTWARE.
 */
 
+#include <fuse.h>
+
 #include <string>
 #include <vector>
 #include <sstream>
@@ -146,8 +148,9 @@ namespace mergerfs
              size_t      attrvalsize,
              int         flags)
     {
-      const ugid::SetResetGuard  uid;
+      const struct fuse_context *fc     = fuse_get_context();
       const config::Config      &config = config::get();
+      const ugid::SetResetGuard  ugid(fc->uid,fc->gid);
 
       if(fusepath == config.controlfile)
         return _setxattr_controlfile(config::get_writable(),

src/statfs.cpp

@@ -124,8 +124,9 @@ namespace mergerfs
     statfs(const char     *fusepath,
            struct statvfs *stat)
     {
-      const ugid::SetResetGuard  uid;
+      const struct fuse_context *fc     = fuse_get_context();
       const config::Config      &config = config::get();
+      const ugid::SetResetGuard  ugid(fc->uid,fc->gid);
 
       return _statfs(config.srcmounts,
                      *stat);

src/symlink.cpp

@@ -64,8 +64,9 @@ namespace mergerfs
     symlink(const char *oldpath,
             const char *newpath)
     {
-      const ugid::SetResetGuard  uid;
+      const struct fuse_context *fc     = fuse_get_context();
       const config::Config      &config = config::get();
+      const ugid::SetResetGuard  ugid(fc->uid,fc->gid);
 
       if(oldpath == config.controlfile ||
          newpath == config.controlfile)

src/truncate.cpp

@@ -76,8 +76,9 @@ namespace mergerfs
     truncate(const char *fusepath,
              off_t       size)
     {
-      const ugid::SetResetGuard  uid;
+      const struct fuse_context *fc     = fuse_get_context();
       const config::Config      &config = config::get();
+      const ugid::SetResetGuard  ugid(fc->uid,fc->gid);
 
       if(fusepath == config.controlfile)
         return -EPERM;

src/ugid.cpp

@@ -0,0 +1,31 @@
+/*
+   The MIT License (MIT)
+
+   Copyright (c) 2014 Antonio SJ Musumeci <trapexit@spawn.link>
+
+   Permission is hereby granted, free of charge, to any person obtaining a copy
+   of this software and associated documentation files (the "Software"), to deal
+   in the Software without restriction, including without limitation the rights
+   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+   copies of the Software, and to permit persons to whom the Software is
+   furnished to do so, subject to the following conditions:
+
+   The above copyright notice and this permission notice shall be included in
+   all copies or substantial portions of the Software.
+
+   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+   THE SOFTWARE.
+*/
+
+#include "ugid.hpp"
+
+#if defined LINUX
+#elif defined OSX
+#else
+pthread_mutex_t mergerfs::ugid::SetResetGuard::lock = PTHREAD_MUTEX_INITIALIZER;
+#endif

src/ugid.hpp

@@ -25,70 +25,12 @@
 #ifndef __UGID_HPP__
 #define __UGID_HPP__
 
-#include <fuse.h>
-
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <unistd.h>
-
-namespace mergerfs
-{
-  namespace ugid
-  {
-    struct SetResetGuard
-    {
-      SetResetGuard()
-      {
-        const struct fuse_context *fc = fuse_get_context();
-
-        olduid   = ::getuid();
-        oldgid   = ::getgid();
-        oldumask = ::umask(fc->umask);
-        newuid   = fc->uid;
-        newgid   = fc->gid;
-        newumask = fc->umask;
-
-        if(olduid != newuid)
-          ::seteuid(newuid);
-        if(oldgid != newgid)
-          ::setegid(newgid);
-      }
-
-      SetResetGuard(uid_t  u,
-                    gid_t  g,
-                    mode_t m)
-      {
-        olduid   = ::getuid();
-        oldgid   = ::getgid();
-        oldumask = ::umask(m);
-        newuid   = u;
-        newgid   = g;
-        newumask = m;
-
-        if(olduid != newuid)
-          ::seteuid(newuid);
-        if(oldgid != newgid)
-          ::setegid(newgid);
-      }
-
-      ~SetResetGuard()
-      {
-        ::umask(oldumask);
-        if(olduid != newuid)
-          ::seteuid(olduid);
-        if(oldgid != newgid)
-          ::setegid(oldgid);
-      }
-
-      uid_t  olduid;
-      gid_t  oldgid;
-      mode_t oldumask;
-      uid_t  newuid;
-      gid_t  newgid;
-      mode_t newumask;
-    };
-  }
-}
-
+#if defined LINUX
+#include "ugid_linux.hpp"
+#elif defined OSX
+#include "ugid_osx.hpp"
+#else
+#include "ugid_mutex.hpp"
+#endif
 
 #endif /* __UGID_HPP__ */

src/ugid_linux.hpp

@@ -0,0 +1,64 @@
+/*
+   The MIT License (MIT)
+
+   Copyright (c) 2014 Antonio SJ Musumeci <trapexit@spawn.link>
+
+   Permission is hereby granted, free of charge, to any person obtaining a copy
+   of this software and associated documentation files (the "Software"), to deal
+   in the Software without restriction, including without limitation the rights
+   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+   copies of the Software, and to permit persons to whom the Software is
+   furnished to do so, subject to the following conditions:
+
+   The above copyright notice and this permission notice shall be included in
+   all copies or substantial portions of the Software.
+
+   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+   THE SOFTWARE.
+*/
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+
+namespace mergerfs
+{
+  namespace ugid
+  {
+    struct SetResetGuard
+    {
+      SetResetGuard(const uid_t _newuid,
+                    const gid_t _newgid)
+      {
+        olduid   = ::geteuid();
+        oldgid   = ::getegid();
+        newuid   = _newuid;
+        newgid   = _newgid;
+
+        if(newgid != oldgid)
+          ::syscall(SYS_setregid,-1,newgid);
+        if(newuid != olduid)
+          ::syscall(SYS_setreuid,-1,newuid);
+      }
+
+      ~SetResetGuard()
+      {
+        if(olduid != newuid)
+          ::syscall(SYS_setreuid,-1,olduid);
+        if(oldgid != newgid)
+          ::syscall(SYS_setregid,-1,oldgid);
+      }
+
+      uid_t  olduid;
+      gid_t  oldgid;
+      uid_t  newuid;
+      gid_t  newgid;
+    };
+  }
+}

src/ugid_mutex.hpp

@@ -0,0 +1,68 @@
+/*
+   The MIT License (MIT)
+
+   Copyright (c) 2014 Antonio SJ Musumeci <trapexit@spawn.link>
+
+   Permission is hereby granted, free of charge, to any person obtaining a copy
+   of this software and associated documentation files (the "Software"), to deal
+   in the Software without restriction, including without limitation the rights
+   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+   copies of the Software, and to permit persons to whom the Software is
+   furnished to do so, subject to the following conditions:
+
+   The above copyright notice and this permission notice shall be included in
+   all copies or substantial portions of the Software.
+
+   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+   THE SOFTWARE.
+*/
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <pthread.h>
+
+namespace mergerfs
+{
+  namespace ugid
+  {
+    struct SetResetGuard
+    {
+      SetResetGuard(const uid_t _newuid,
+                    const gid_t _newgid)
+      {
+        pthread_mutex_lock(&lock);
+
+        olduid   = ::geteuid();
+        oldgid   = ::getegid();
+        newuid   = _newuid;
+        newgid   = _newgid;
+
+        if(newgid != oldgid)
+          setegid(newgid);
+        if(newuid != olduid)
+          seteuid(newuid);
+      }
+
+      ~SetResetGuard()
+      {
+        if(olduid != newuid)
+          seteuid(newuid);
+        if(oldgid != newgid)
+          setegid(newgid);
+      }
+
+      uid_t  olduid;
+      gid_t  oldgid;
+      uid_t  newuid;
+      gid_t  newgid;
+
+      static pthread_mutex_t lock;
+    };
+  }
+}

src/ugid_osx.hpp

@@ -0,0 +1,58 @@
+/*
+   The MIT License (MIT)
+
+   Copyright (c) 2014 Antonio SJ Musumeci <trapexit@spawn.link>
+
+   Permission is hereby granted, free of charge, to any person obtaining a copy
+   of this software and associated documentation files (the "Software"), to deal
+   in the Software without restriction, including without limitation the rights
+   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+   copies of the Software, and to permit persons to whom the Software is
+   furnished to do so, subject to the following conditions:
+
+   The above copyright notice and this permission notice shall be included in
+   all copies or substantial portions of the Software.
+
+   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+   THE SOFTWARE.
+*/
+
+#include <sys/types.h>
+#include <sys/unistd.h>
+
+namespace mergerfs
+{
+  namespace ugid
+  {
+    struct SetResetGuard
+    {
+      SetResetGuard(const uid_t _newuid,
+                    const gid_t _newgid)
+      {
+        olduid   = ::geteuid();
+        oldgid   = ::getegid();
+        newuid   = _newuid;
+        newgid   = _newgid;
+
+        if(newgid != oldgid || newuid != olduid)
+          pthread_setugid_np(newuid,newgid);
+      }
+
+      ~SetResetGuard()
+      {
+        if(newgid != oldgid || newuid != olduid)
+          pthread_setugid_np(newuid,newgid);
+      }
+
+      uid_t  olduid;
+      gid_t  oldgid;
+      uid_t  newuid;
+      gid_t  newgid;
+    };
+  }
+}

src/unlink.cpp

@@ -22,6 +22,8 @@
    THE SOFTWARE.
 */
 
+#include <fuse.h>
+
 #include <errno.h>
 #include <unistd.h>
 
@@ -71,8 +73,9 @@ namespace mergerfs
     int
     unlink(const char *fusepath)
     {
-      const ugid::SetResetGuard  ugid;
+      const struct fuse_context *fc     = fuse_get_context();
       const config::Config      &config = config::get();
+      const ugid::SetResetGuard  ugid(fc->uid,fc->gid);
 
       if(fusepath == config.controlfile)
         return -EPERM;

src/utimens.cpp

@@ -22,8 +22,11 @@
    THE SOFTWARE.
 */
 
+#include <fuse.h>
+
 #include <errno.h>
-#include <unistd.h>
+#include <fcntl.h>
+#include <sys/stat.h>
 
 #include <string>
 #include <vector>
@@ -31,7 +34,6 @@
 #include "ugid.hpp"
 #include "fs.hpp"
 #include "config.hpp"
-#include "assert.hpp"
 
 using std::string;
 using std::vector;
@@ -73,8 +75,9 @@ namespace mergerfs
     utimens(const char            *fusepath,
             const struct timespec  ts[2])
     {
-      ugid::SetResetGuard   ugid;
-      const config::Config &config = config::get();
+      const struct fuse_context *fc     = fuse_get_context();
+      const config::Config      &config = config::get();
+      const ugid::SetResetGuard  ugid(fc->uid,fc->gid);
 
       if(fusepath == config.controlfile)
         return -EPERM;

src/write.cpp

@@ -128,8 +128,7 @@ namespace mergerfs
           off_t                  offset,
           struct fuse_file_info *fi)
     {
-      const ugid::SetResetGuard  ugid;
-      const config::Config      &config   = config::get();
+      const config::Config &config = config::get();
 
       if(fusepath == config.controlfile)
         return _write_controlfile(config::get_writable(),

src/write_buf.cpp

@@ -28,7 +28,6 @@
 #include <fuse.h>
 
 #include "config.hpp"
-#include "ugid.hpp"
 #include "fileinfo.hpp"
 #include "write.hpp"
 
@@ -93,8 +92,7 @@ namespace mergerfs
               off_t                  offset,
               struct fuse_file_info *fi)
     {
-      const ugid::SetResetGuard  ugid;
-      const config::Config      &config = config::get();
+      const config::Config &config = config::get();
 
       if(fusepath == config.controlfile)
         return _write_buf_controlfile(config.controlfile,