Tema 1 retele

#include <unistd.h>
#include <stdio.h>
#include <sys/types.h>
#include <string.h>
#include <stdlib.h>

/*Programul are nevoie de un fisier numit "config.txt" care sa contina o lista cu username-urile valide pentru a functiona */
void executeCmd(char* cmd) {
  int pfd[2];
  char mesaj[500000];
  memset(mesaj, '\0', sizeof(mesaj));
  /* cream pipe-ul */
  if (pipe (pfd) == -1)
    {
      fprintf (stderr, "pipe\n");
      exit (1);
    }

  /* cream primul copil */
  switch (fork ())
    {
    case -1:
      fprintf (stderr, "fork - 1\n");
      exit (1);
    case 0:
       close (1);
       /*duplicam descriptorul de scriere al pipe-ului
         la iesirea standard (1)*/
      if (dup (pfd[1]) != 1)
        {
          fprintf (stderr, "dup - 1\n");
          exit (1);
        }
      /* putem inchide descriptorii pipe-ului,
         din moment ce am realizat duplicarea */
      close (pfd[0]);
      close (pfd[1]);

      char* index;
      char* comanda[10];
      int start = 0, i=0;
      index = strstr(cmd, " ");
      while(index != NULL) {
        index[0] = '\0';
        comanda[i++] = &cmd[start];
        start += strlen(&cmd[start]) + 1;
        index = strstr(&cmd[start], " ");
      }
      comanda[i] = &cmd[start];
      comanda[i+1] = NULL;
      execvp(comanda[0], comanda);
      fprintf (stderr, "exec - 1 this\n");
      exit(1);
    }
  /* cream al doilea copil */
  switch (fork ())
    {
    case -1:
      fprintf (stderr, "fork - 2\n");
      exit (1);
    case 0:
      ;
      char raspuns[500000];
      read(pfd[0], raspuns, 499999);
      char* ptr; int cnt = 0;
      ptr = strstr(raspuns, "\n");
      while(ptr != NULL) {
        ptr = strstr(ptr+1, "\n");
        cnt++;
      }
      cmd[4] = '\0';
      if(strcmp(cmd, "grep") == 0)        sprintf(raspuns, "Numarul de linii relevante: %d", cnt);
      int lungimeRaspuns = strlen(raspuns);
      write(pfd[1], &lungimeRaspuns, sizeof(int));
      write(pfd[1], raspuns, strlen(raspuns));
      close(pfd[1]);
      close(pfd[0]);
      exit (1);
    }

  /* parintele */
  while (wait(NULL) != -1);
  int lungimeRaspuns;
  read(pfd[0], &lungimeRaspuns, sizeof(int));
  read(pfd[0], mesaj, lungimeRaspuns);
  printf("Raspunsul are %d bytes.\nRaspuns:\n%s", lungimeRaspuns, mesaj);
  close (pfd[0]);
  close (pfd[1]);
  memset(cmd, '\0', 500);
  return;
}



int main() {
char name[50];
char users[100][50];
FILE *fisier = fopen("config.txt", "r");
int i = 0, j, gasit = 0;

while (fgets(users[i], sizeof(users[i]), fisier) != NULL) {
  users[i][strlen(users[i])-1] = '\0'; i++;
}

printf("\nUsername: ");
fgets(name, 49, stdin);
name[strlen(name)-1] = '\0';
while(strcmp(name, "quit") != 0) {
  gasit = 0;
  for(j = 0; j < i; j++) {
    if(strcmp(name, users[j]) == 0)  gasit = 1;
  }
  if(gasit) break;
  printf("Usernameul nu este valid.\n");
  printf("\nUsername: ");
  fgets(name, 49, stdin); name[strlen(name)-1] = '\0';
}

if(strcmp(name, "quit") == 0) return 0;

printf("Ai fost autentificat cu succes.\n");

char cmd[500];
printf("\nComanda: ");
fgets(cmd, 499, stdin);
cmd[strlen(cmd)-1] = '\0';
while (strcmp(cmd, "quit") != 0) {
  executeCmd(cmd); printf("\nComanda: ");
  fgets(cmd, 499, stdin); cmd[strlen(cmd)-1] = '\0';
}
return 0;
}