Operating Systems Project

This project is based in the language C and it make uses of:

• Threads.
• Semaphores
• Condition variables
• Shared memory
• Processes
• Pipes

This Project is meant to work on Linux 19.04

Lore

Based on the San Francisco's Airport in real life, a Simation Manager runs a system where flights are controled by a Control Tower. Each flight can be declined, received, or be holded. There is also support for emergency flights.

Flow

1. The Simulation Manager starts the program. In the simulation Manager:
   • Commands are read from an input Pipe, and proceed to be parsed, meaning they can be accepted or denied.
   • Accepted commmands are moved to a linked list where they wait to be scheduled.
   • A Thread using conditional Timed wait schedules the flights, aka creates threads, to start in the correct time delta.
2. After a flight is created:
   • Sends a message using a mssage queue to the control Tower waiting for an available slot.
3. Control Tower:
   • Receives and Responds to incoming messages from the queue
   • Schedules flights to land, hold (6th and above on the queue), or sends them wait (either in case of no fuel or if the airport is full). Supports Emergency flights.

Additional notes

• Upon a flight as landed, its respective thread is released.\
• On SIGUSR1 the program prints runtime stats to stdout.
• On SIGINT the program closes the pipe, waits for all flights allready instanciated to leave and then clean resources and leaves.

General usage

To compile and run there it is included a makefile There is also an included tester bash script that will input multiple commands into the program (written using the sh shell);

Known Bugs/Errors

• Signals (like SIGBUS/ SIGALARM) were not treated not to disrupt the program and, if used, will kill the program

Files and more

Alongside this ReadME this project includes:

• Main.c and Main.h

  • Contains our Simualtion Manager, it creates every resource needed and then handles reading from the pipe and creates flights in the current eta

• ControlTower.c and ControlTower.h

  • The control tower is a secondary process that control what flights do, they can either land/depart, hold, be rejected or redirected

• Parser.c and Parser.h

  • Function that handles parsing the commands from the pipe and returning a system readable struct

• Structures.c and Structures.h

  • Backend file that handles some structures required for the program

• config.txt

  • File that contains a number of required variables necessary to the program

• tester.sh

  • Simples script that automatically inputs commands to the pipe

• makefile

  • File that generates the executable

Collaborators

Gabriel Fernandes