CS471/571 - Operating Systems

Displaying ./code/System-calls/cp.c

#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>

#define K	1024

extern int errno;

void putstr(char *mesg)
{
  write(STDERR_FILENO, mesg, strlen(mesg));
}

void printerror(char *mesg)
{
  putstr(mesg);
  switch(errno) {
    case EACCES: putstr(": Access denied\n"); break;
    case ENOENT: putstr(": File not found\n"); break;
    case EPERM:  putstr(": Permission denied\n"); break;
    default: putstr(": Some other error\n");
  }
}

int main(int argc, char *argv[])
{
  if (argc < 3) {
    putstr("Usage: cp <input> <output>\n");
    return 1;
  }

  int input = open(argv[1], O_RDONLY);
  if (input < 0) {
    printerror("input");
    return 1;
  }
  int output = open(argv[2], O_WRONLY | O_CREAT | O_TRUNC, 0666);
  if (output < 0) {
    printerror("output");
    return 1;
  }

  char block[K];
  int r;	// How much was read by read()

  while ( (r = read(input, block, K)) > 0 ) {
    write(output, block, r);
  }

  close(input);
  close(output);

  return 0;
}