solab4pb1

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <ctype.h>
#include <sys/stat.h>
#include <string.h>

int getFD(const char *const fname, int flags, int perm) {
  int fd = open(fname, flags, perm);
  if (fd < 0) {
    perror("");
    exit(1);
  }
  return fd;
}

void closeFD(int fd) {
  if (close(fd) < 0) {
    perror("");
    exit(1);
  }
}

int main(int argc, char *argv[]) {

  if (argc != 4) {
    fprintf(stderr, "Wrong usage!\n");
    exit(1);
  }

  int fd1 = getFD(argv[1], O_RDONLY, 0);

  int lower = 0, upper = 0, digits = 0, cnt = 0;
  char ch;
  while (read(fd1, &ch, 1) > 0) {
    if (islower(ch)) {
      lower++;
    }
    if (isupper(ch)) {
      upper++;
    }
    if (isdigit(ch)) {
      digits++;
    }
    if (ch == argv[3][0]) {
      cnt++;
    }
  }

  int dim;
  struct stat buff;
  if (fstat(fd1, &buff) == -1) {
    perror("fstat");
    exit(1);
  }
  dim = buff.st_size;

  int fd2 = getFD(argv[2], O_RDWR | O_CREAT, S_IWUSR | S_IRUSR);

  char s[30];
  sprintf(s, "nr lower: %d\n", lower);
  write(fd2, s, strlen(s));
  sprintf(s, "nr upper: %d\n", upper);
  write(fd2, s, strlen(s));
  sprintf(s, "nr digits: %d\n", digits);
  write(fd2, s, strlen(s));
  sprintf(s, "nr %c: %d\n", argv[3][0], cnt);
  write(fd2, s, strlen(s));
  sprintf(s, "size: %d\n", dim);
  write(fd2, s, strlen(s));

  closeFD(fd1);
  closeFD(fd2);
  return 0;
}