Development and Implementation of a File System for Gannet Virtual ...

ack onto the stack to be reused and the stat structure is erased from the file
descriptor table.
4.2.2 Directory Operations Implementation
GannetFS file system provides full POSIX compliant interfaces for directory
operation. There are three interfaces over files operation, namely mkdir(),
opendir(), closedir() and readdir(). GannetFS treats directory as a file. Therefore,
those interface is similar to creat(), open(), close(), and read() function on files
operation, respectively.
mkdir() function is similar to creat() function on file operation. However, mkdir()
function does not allocate a slot on file descriptor table. As opendir() is called, a slot
on file descriptor table is allocated. Unlike open() function on file operation, if the
directory is not exist, instead of creating new directory, opendir() function
terminates with error. Another difference between them, instead of returning a file
descriptor, opendir() function returns a file DIR pointer which is used by readdir()
to obtain an directory entry. Readdir() returns the next directory entry form the
data block on each call. Instead of reading data byte per byte on data blocks,
Readdir() reads directory entry one by one. The closedir() function frees a slot on
file descriptor table that allocated by opendir() and closes the directory.
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