/* C standard headers */
#include <errno.h>
#include <inttypes.h>
#include <setjmp.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* Linux headers */
#include <dirent.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/ptrace.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <sys/user.h>
/* Architecture-specific headers */
#include <asm/ptrace.h>
#include <asm/unistd.h>

#include <signal.h>
#include <assert.h>

typedef void fun_moved_from_context();
//using namespace std;
void attachTo(pid_t pid, int id) {
    long ret = ptrace (PTRACE_ATTACH, pid, NULL, NULL);
    printf("%i  attachTo: %ld\n", id, ret);
}
void seizeTo(pid_t pid, int id) {
    long ret = ptrace (PTRACE_SEIZE, pid, NULL, NULL);
    //assert(ret > 0);
    printf("%i  seizeTo: %ld\n", id, ret);
}
void detachFrom(pid_t pid, int id) {
    long ret = ptrace (PTRACE_DETACH, pid, NULL, NULL);
    printf("%i  detachFrom: %ld\n", id, ret);
}
void setOptions(pid_t pid, int id) {
    long ret = ptrace(PTRACE_SETOPTIONS, pid, NULL, (void*) (PTRACE_O_TRACECLONE | PTRACE_O_TRACEEXEC | PTRACE_O_TRACEEXIT | PTRACE_O_TRACEFORK | PTRACE_O_TRACEVFORK));
    printf("%i  setOptions: %ld\n", id, ret);
}
void setVarData(pid_t pid, volatile bool* can_run, void* data, int id) {
    long ret = ptrace(PTRACE_POKEDATA, pid, (void*)can_run, (void*)data);
    printf("%i  setVarData: %ld\n", id, ret);
}
void cont(pid_t pid, int id) {
    long ret = ptrace (PTRACE_CONT, pid, NULL, NULL);
    printf("%i  cont: %ld\n", id, ret);
}
void interrupt(pid_t pid, int id) {
    long ret = ptrace (PTRACE_INTERRUPT, pid, NULL, NULL);
    printf("%i  interrupt: %ld\n", id, ret);
}
void debug(int id) {
    int status;
    while (true) {
        printf("%i  while\n", id);
        sleep(1);
        struct user_regs regs;
        pid_t recv = wait(&status);
        if (recv == -1) {
            printf("%i  Debugger exiting\n", id);
            return 0;
        } else {
            if (WIFSTOPPED(status)) {
                int signal = WSTOPSIG(status);
                printf("%i  signal: %i\n",id,signal);
                switch (signal) {
                    case SIGTRAP: {
                        int event_code = (status >> 8) ^ SIGTRAP;
                        printf("%i  event_code: %i\n",id,event_code);
                        switch (event_code) {
                            case PTRACE_EVENT_FORK << 8:
                                printf("%i  FORK EVENT.\n", id);
                                cont(recv,id);
                                break;
                            case PTRACE_EVENT_EXIT << 8:
                                printf("%i  %li exited.\n", id, recv);
                                return 0;
                                break;
                            default: {
                                printf("%i  recv: %i ; status: %i\n", id, recv, status);
                                long ret=ptrace (PTRACE_GETREGS, recv, NULL, &regs);
                                regs.uregs[15] += 2;//addr_size;
                                printf("%i  p: new PC: %lx\n", id, regs.uregs[15]);
                                ptrace (PTRACE_SETREGS, recv, NULL, &regs);
                                cont(recv,id);
                            }
                        }
                        break;
                    }
                    default: {
                        cont(recv,id);
                        break;
                    }
                }
            }

        }
    }
}

int main() {
    int pid;
    int me = getpid();
    printf("Hello, I am %d\n", me);
    printf("pid:");
    scanf("%d",&pid);
    if (pid == 0) {
        printf("bkpt asm\n");
        asm("bkpt");
    } else {
        attachTo(pid, me);
        printf("start waitpid\n");
        waitpid(pid, NULL, __WALL);
        printf("end waitpid\n");
        setOptions(pid, me);
        cont(pid,me);
        debug(me);
    }
    return 0;
}