fsop is a command-line utility program for demonstrating various system calls for files in action. fsop allows the user to create, read, write and inspect regular, unnamed and named pipes in their target platform's filesystem.
Execution & Usage
- For execution, ensure that either the executable provided alongside the copy of the program (see notes) or one built manually for your target architecture (see building) is available.
- ### Usage
./fsop.out [-d DIRECTORY] [-q] [-h] {create,read,write,inspect} ...
./fsop.out create [-h] [-p PERMS] [-t {pipe,regular}] [-o] path
./fsop.out read [-h] [-p] [-b OFFSET...] [-B {CUR,END,SET}...] [-c BYTE-COUNT...] [path]
./fsop.out write [--lbuf] [-h] [-A] [-t] [-b OFFSET...] [-B {CUR,END,SET}...] [-p] [path]
./fsop.out inspect [-h] [-l] path...
- Information about usage, flags and options can also be accessed by executing
./fsop --help on a terminal.
- More information about actions can be accessed using the
--help flag alongside the specific action, for example ./fsop.out create --help to view help on how to use create.
Examples
- Create a new regular file, named
file.txt, with permissions rwx for all users (simple creation, no data written): ./fsop.out create file.txt --type regular --perms ugo+rwx
- Read the complete contents of the file
myfile.txt (provided it exists): ./fsop.out read myfile.txt
- Write input provided on STDIN to offset 40 from the beginning to the file
myfile.txt (provided file exists): ./fsop.out write myfile.txt --offset 40 --offset-base SET
- Inspect all files under the folder
/dev: ./fsop.out inspect /dev/*
System Call Usage
| Task | System Call(s) Used |
| Create New Files | creat, mknod |
| Access Existing Files | open, read, write, lseek (lseek64), close |
| Manipulate the Inode | chdir, chmod, stat (fstat, lstat, stat64, ...) |
| Advanced System Calls | dup, pipe, unlink |
| Miscellaneous (non-fs) | fork, getpid, signal, exit, getpwuid, getgrgid |
Building
- ### Prerequisites The following software is required prior compilation of the source:
- GNU C++ Compiler (g++) version 7 or newer, or any equivalent C++ compiler with support for C++17.
- GNU Make or equivalent to execute commands from makefiles (optional, recommended). See notes for a workaround for compilation without Make.
- ### Compilation
- Prior to compilation, clean up any remaining object and executable files from previously incomplete builds, by running
make clean.
- To generate object files and executables, run the default make recipe, using
make.
Notes
- The executable provided alongside the project has been compiled on a 64-bit (arch: x86_64) Windows machine running the Windows Subsystem for Linux (WSL) (kernel version: 5.10.102.1-microsoft-standard-WSL2), using the GNU C++ Compiler v9.3.0.
- If GNU make is not installed on the target machine being used for compilation, then either it may be installed via
sudo apt install make (recommended), or the make.bash script supplied alongside the source may be utilized to execute the equivalent Make recipes. To use the script, in the compilation steps replace the usage of make with ./make.bash (e.g.: make clean -> ./make.bash clean).
About
Created by: Kinshuk Vasisht
Roll Number: 19
M.Sc. Computer Science
Department of Computer Science, University of Delhi
Bibliography
- The Design of the UNIX Operating System, Maurice J. Bach
- Linux Manual Pages for System Calls and Functions: man7, linux.die.net
Reference
