csetjmp

---

1. Signal Handling:

#include <signal.h>
#include <setjmp.h>

jmp_buf env;

void signal_handler(int signum) {
  longjmp(env, signum);
}

int main() {
  if (setjmp(env) == 0) {
    // Install signal handler
    signal(SIGINT, signal_handler);
    
    // Main program loop
    while (true) {
      sleep(1);
      printf("Running normally...\n");
    }
  } else {
    // Signal was caught
    printf("Signal %d caught!\n", signum);
  }
  
  return 0;
}

2. Error Handling with Multiple Return Points:

#include <setjmp.h>

jmp_buf error_env;

int func() {
  if (setjmp(error_env) != 0) {
    return -1;  // Error occurred, jump to error handling code
  }
  
  // Perform some operations...
  
  return 0;  // No error occurred
}

int main() {
  if (setjmp(error_env) == 0) {
    func();
  } else {
    // Error occurred in func(), handle it here
    printf("An error occurred!\n");
  }
  
  return 0;
}

3. Implementing a Stack Machine:

#include <setjmp.h>
#include <stack>

jmp_buf env;

void stack_push(jmp_buf* env, int value) {
  stack.push(value);
  if (stack.size() > max_stack_size) {
    longjmp(*env, 1);
  }
}

int stack_pop(jmp_buf* env) {
  if (stack.empty()) {
    longjmp(*env, 2);
  }
  
  return stack.top();
  stack.pop();
}

int main() {
  if (setjmp(env) != 0) {
    // Stack overflow or underflow occurred
    handle_error();
  }
  
  // Push and pop values from the stack...
  
  return 0;
}

4. Implementing a Coroutine:

#include <setjmp.h>

jmp_buf env;
bool running = false;

void coroutine() {
  while (running) {
    // Yield control to the caller
    if (setjmp(env) == 0) {
      // Resume execution of the coroutine
      yield();
    } else {
      // Coroutine has been stopped
      running = false;
    }
  }
}

int main() {
  if (setjmp(env) == 0) {
    // Start the coroutine
    running = true;
    coroutine();
  } else {
    // Coroutine has finished
    printf("Coroutine has stopped.\n");
  }
  
  return 0;
}

5. Context Switching between Threads:

#include <setjmp.h>
#include <thread>

jmp_buf env;

void* thread_func(void* arg) {
  if (setjmp(env) == 0) {
    // Thread's main logic
    while (true) {
      printf("Thread running...\n");
      sleep(1);
    }
  } else {
    // Context switch to main thread
    longjmp(env, 1);
  }
  
  return nullptr;
}

int main() {
  // Create a new thread
  thread t(thread_func, nullptr);
  
  while (true) {
    // Context switch to the thread
    if (setjmp(env) == 0) {
      longjmp(env, 2);
    } else {
      // Back in the main thread
      printf("Main thread running...\n");
      sleep(1);
    }
  }
  
  t.join();
  return 0;
}

6. Implementing a Pause/Resume Mechanism:

#include <setjmp.h>

jmp_buf env;

void pause() {
  if (setjmp(env) == 0) {
    // Suspend execution
    longjmp(env, 1);
  }
}

void resume() {
  longjmp(env, 2);
}

int main() {
  if (setjmp(env) == 0) {
    // Main program loop
    while (true) {
      printf("Running normally...\n");
      pause();
      printf("Resumed...\n");
    }
  } else {
    // Resumed from pause()
  }
  
  return 0;
}

7. Implementing a Time-Limited Function:

#include <setjmp.h>
#include <signal.h>

jmp_buf env;
timer_t timer_id;

void timeout_handler(int signum) {
  longjmp(env, 1);
}

int timed_function() {
  if (setjmp(env) == 0) {
    // Install timeout handler
    signal(SIGALRM, timeout_handler);
    
    // Set a timer to expire after a certain timeout
    itimer_spec timer_spec;
    timer_spec.it_value.tv_sec = 10;
    timer_spec.it_value.tv_nsec = 0;
    timer_create(CLOCK_REALTIME, &timer_spec, &timer_id);
    
    // Execute the function
    while (true) {
      // Perform some operations...
      sleep(1);
    }
  } else {
    // Timeout occurred
    printf("Timeout!\n");
    timer_delete(timer_id);
  }
  
  return 0;
}

int main() {
  timed_function();
  return 0;
}

8. Implementing a Non-Blocking I/O Function:

#include <setjmp.h>
#include <sys/select.h>

jmp_buf env;

int non_blocking_read(int fd) {
  if (setjmp(env) == 0) {
    // Set up non-blocking I/O
    fcntl(fd, F_SETFL, O_NONBLOCK);
    
    // Wait for data to become available
    fd_set read_set;
    FD_ZERO(&read_set);
    FD_SET(fd, &read_set);
    
    int result = select(fd + 1, &read_set, nullptr, nullptr, nullptr);
    if (result > 0) {
      // Data is available
      return read(fd, buf, sizeof(buf));
    } else {
      // No data available, try again
      longjmp(env, 1);
    }
  } else {
    // No data available
    return -1;
  }
}

int main() {
  while (true) {
    int result = non_blocking_read(fd);
    if (result > 0) {
      // Process the data
    }
  }
  
  return 0;
}

9. Implementing a Custom Scheduler:

#include <setjmp.h>

jmp_buf tasks[MAX_TASKS];
int current_task = 0;

void task_func(int task_id) {
  while (true) {
    // Perform some task-specific operations...
    
    // Yield to the next task
    if (setjmp(tasks[current_task]) == 0) {
      current_task = (current_task + 1) % MAX_TASKS;
      longjmp(tasks[current_task], 1);
    }
  }
}

int main() {
  // Initialize tasks
  for (int i = 0; i < MAX_TASKS; i++) {
    if (setjmp(tasks[i]) == 0) {
      task_func(i);
    }
  }
  
  return 0;
}

10. Error Handling with Structured Exception Handling (SEH)

#include <setjmp.h>
#include <windows.h>

jmp_buf env;

__try {
  // Code that may cause an exception
  // ...
} __except (EXCEPTION_EXECUTE_HANDLER) {
  longjmp(env, 1);
}

int main() {
  if (setjmp(env) == 0) {
    // Main program loop
    // ...
  } else {
    // An exception occurred
    // ...
  }
  
  return 0;
}