Signals

Real-Time Signals Communication

Overview

This project demonstrates inter-process communication (IPC) in Linux using real-time signals to simulate terminate and abort functionality. It consists of two files:

1. Receiver (rcv.c): Listens for real-time signals and performs specific actions based on the received signal's data.
2. Sender (snd.c): Sends real-time signals with associated data to the receiver process.

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Features

• Uses real-time signals (SIGRTMIN) for reliable communication.
• Signal Data Handling:
  • 0: Receiver terminates gracefully.
  • 1: Receiver aborts with a core dump.
• The use of Signals:
  • sigaction for setting up advanced signal handlers.
  • sigqueue for sending signals with additional data.

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How It Works

Receiver (rcv.c)

• Registers a signal handler for SIGRTMIN using sigaction.
• Processes signal data received via the si_value.sival_int field of siginfo_t.
• Performs the following:
  • Data 0: Logs a termination message and exits.
  • Data 1: Logs an abort message and triggers a core dump.
  • Logs a message for any other data.

Sender (snd.c)

• Accepts the following command-line arguments:
  • PID: Process ID of the receiver.
  • Data: Integer value (0 or 1).
• Uses sigqueue to send SIGRTMIN with the specified data to the receiver.

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Setup and Usage

Compilation

gcc -o r rcv.c
gcc -o s snd.c

Running the Receiver

Start the receiver application to listen for real-time signals:

./r

• The receiver will print its PID (Process ID) upon launch.

Sending Signals

Use the sender application to send a signal to the receiver:

./s <pid> <0 or 1>

Arguments:

• <pid>: Process ID of the running receiver (printed by the receiver).
• <0 or 1>: Integer data to send:
  • 0: Terminates the receiver.
  • 1: Aborts the receiver with a core dump.

Example:

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Technical Highlights

• Real-Time Signals: Uses SIGRTMIN for queuing and passing additional data.
• sigaction: Allows access to extended signal data using the SA_SIGINFO flag.
• sigqueue: Sends signals with payload data encapsulated in a union sigval.