KageNuPlx

tfgets.c

#define _POSIX_C_SOURCE 1
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <string.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <assert.h>
//
// Helper func
int file_pipes(FILE* files[2]){
    // Array for fd
    int fds[2];
    // Åben pipes
    assert(pipe(fds) == 0);
    // Nu får vi bare file-objector
    FILE *read_end = fdopen(fds[0], "r");
    FILE *write_end = fdopen(fds[1], "w");
    files[0] = read_end;
    files[1] = write_end;
    if (read_end == NULL || write_end == NULL)
        return 1;
    

    return 0;
}

// Handler for recognizing timeout
char timeout;
void handler(int signum){
    switch(signum){
        case SIGALRM:
            timeout = 1;
            break;
        case SIGUSR1:
            timeout = 0;
            break;
    }
    
}
char *tfgets(char *s, int size, FILE *stream){
    timeout = 0;
    // This needs to wait five seconds then return
    // make two children. One for fgets, one for sleeping
    signal(SIGUSR1, handler);
    signal(SIGALRM, handler);
    pid_t fget_pid;
    alarm(5);
    FILE *files[2];
    assert(file_pipes(files) == 0);
    if (( fget_pid = fork()) == 0){
        // Time to reading child
        fclose(files[0]);
        char buf[size];
        memset(buf, 0, size);
        fgets(buf, size, stream);
        // We need to send signal before writing to avoid blocking
        kill(getppid(), SIGUSR1);
        fwrite(buf, sizeof(char), size, files[1]);
        fclose(files[1]);
        exit(0);
    }
    fclose(files[1]);
    pause();
    if(timeout){
        return NULL;
    } else {
        fread(s, sizeof(char), size, files[0]);
        fclose(files[0]);
    }
    //return 0;
    return s;
}

int main(){
    printf("Enter your name: ");
    fflush(stdout);
    char s[64];
    char* read = tfgets(s, 64, stdin);
    if(read == NULL){
        printf("\nTimed out\n");
    }
    else{
        printf("Hello %s", s);
    }
}