In the area of “requires POSIX filesystem semantics” what is typically meant is: allows hierarchical file names and resolution (., .., …) supports at least close-to-open semantics umask/unix permissions, 3 filetimes 8bit byte support supports atomic renames on same filesystem fsync()/dirfsync() durability gurantee/limitation supports multi-user protection (resizing file returns 0 bytes not previous content) rename … Read more
Can’t give you the ultimate answer, but consider these 2 points: The feature is of little use to the mainstream user (98% of all users?), so why implementing it, if nobody uses it. Storage space was expensive in the past, so why wasting it on a feature that almost nobody will use?
This is a more elegant way: function script_path() local str = debug.getinfo(2, “S”).source:sub(2) return str:match(“(.*/)”) end print(script_path())
Take a look at FUSE: http://fuse.sourceforge.net/ This will allow you to write a filesystem without having to actually write a device driver. From there, I’d start with a single file. Basically create a file that’s (for example) 100MB in length, then write your routines to read and write from that file. Once you’re happy with … Read more
I’m not sure your list is quite correct. It depends on what you mean by a file system. If you mean a file system that is mountable in an operating system and usable by any application that reads and writes files using POSIX calls, then GridFS doesn’t really qualify. It is just how MongoDB stores … Read more
This is straight from Andrew Gerrand’s 10 things you (probably) don’t know about Go: var fs fileSystem = osFS{} type fileSystem interface { Open(name string) (file, error) Stat(name string) (os.FileInfo, error) } type file interface { io.Closer io.Reader io.ReaderAt io.Seeker Stat() (os.FileInfo, error) } // osFS implements fileSystem using the local disk. type osFS struct{} … Read more
What you’re doing seems perfectly OK, provided you’re using the POSIX “raw” IO syscalls such as read(), write(), lseek() and so forth. If you use C stdio (fread(), fwrite() and friends) or some other language runtime library which has its own userspace buffering, then the answer by “Tilo” is relevant, in that due to the … Read more
Most filesystems (but not all) use locking to guard concurrent access to the same file. The lock can be exclusive, so the first user to get the lock gets access – subsequent users get a “access denied” error. In your example scenario, user A will be able to read the file and gets the file … Read more
External fragmentation Total memory space is enough to satisfy a request or to reside a process in it, but it is not contiguous so it can not be used. Internal fragmentation Memory block assigned to process is bigger. Some portion of memory is left unused as it can not be used by another process.
Copied from http://technet.microsoft.com/en-us/library/cc750354.aspx What’s FAT? FAT may sound like a strange name for a file system, but it’s actually an acronym for File Allocation Table. Introduced in 1981, FAT is ancient in computer terms. Because of its age, most operating systems, including Microsoft Windows NT®, Windows 98, the Macintosh OS, and some versions of UNIX, … Read more