user_level.c

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <ctype.h>
#include <string.h>
#define help_text "usage: cipher [-devhm] [-p PASSWD] <infile> <outfile>\n "\
                  "\n "\
                  "Command descriptions:\n "\
                  "  p   Pre-supply password for encryption/decrytion to use\n "\
                  "  e   Encrypt your infile to your outfile with a supplied password\n "\
                  "  d   Decrypt your infile to your outfile with a supplied password\n "\
                  "  v   Display the current running version of the program\n "\
                  "  m   Map files using mmap system calls\n"


#define __NR_xcrypt 349 /* our private syscall number */

struct xcryptParam {
    int encrypt;
    char *infile;
    char *outfile;
    char *password;
    int passlen;
};

int main(int argc, char *argv[])
{
    int rc;
    struct xcryptParam *passParam = malloc(sizeof(struct xcryptParam));
    int c;
    int j = 0;
    int index;
    char temp_buf[16];
    char *pass = NULL;
    int dflag = 0;
    int eflag = 0;
    char *inFile = NULL;
    char *outFile = NULL;

    /* Initially set opterr flag to 0 for operations processing */
    opterr = 0;

    while ((c = getopt(argc, argv, "deph:")) != -1) {
        switch(c) {
            case 'd':
                 // Check if user has supplied to encrypt and decrypt the file. Throw error
                if(eflag == 1) {
                    fprintf(stderr, "Error: You must either supply an option to encrypt OR decrypt.\n");
                    exit(EXIT_FAILURE);
                }
                passParam->encrypt = 0;
                dflag = 1;
                break;
            case 'e':
                 // Check if user has supplied to encrypt and decrypt the file. Throw error
                if(dflag == 1) {
                    fprintf(stderr, "Error: You must either supply an option to encrypt OR decrypt.\n");
                    exit(EXIT_FAILURE);
                }
                passParam->encrypt = 1;
                eflag = 1;
                break;
            case 'h':
                printf("%s\n", help_text);
                return 1;
            case 'p':
                //pass = optarg;
                //printf("%s\n", optarg);
                break;
            case '?':
                if(optopt == 'p')
                    fprintf(stderr, "Option -%c requires an argument.\n", optopt);
                else if(isprint(optopt))
                    fprintf(stderr, "Unknown option '-%c.\n", optopt);
                else
                    fprintf(stderr, "Unknown option character '\\x%x'.\n", optopt);
                    return 1;
            default:
                abort();
        }
    }

  if((dflag == 0) && (eflag == 0)) {
       printf("Error: Encrypt/Decrypt has not been selected...\nThis is an encrypting program :-)\n");
       exit(EXIT_FAILURE);
  }

  for(index = optind; index < argc; index++) {
      if (j == 0) {
        pass = argv[index];
      }
      else if(j == 1) {
                inFile = argv[index];
                printf("1st argument: %s\n", argv[index]);
           }
      else if(j == 2) {
                outFile = argv[index];
                printf("2nd argument: %s\n", argv[index]);
           }
      else
          printf("Non-option argument %s\n", argv[index]);
      j++;

  }
printf("Encrypt: %i\n", passParam->encrypt);
  if((inFile == NULL)) {
       printf("Error: No [in]file supplied\n");
       exit(EXIT_FAILURE);
  }
  else {
      passParam->infile = inFile;
  }

  if((outFile == NULL)) {
       printf("Error: No [out]file supplied\n");
       exit(EXIT_FAILURE);
  }
  else {
      passParam->outfile = outFile;
  }

  strcpy(temp_buf, pass); // Move the streams contents to a buff (for checking and proccessing purposes)
  passParam->password = pass;
  passParam->passlen = strlen(pass);

    rc = syscall(__NR_xcrypt, (void *)passParam);
    if (rc == 0)
        printf("syscall returned %d\n", rc);
    else
        printf("syscall returned %d (errno=%d)\n", rc, errno);

    exit(rc);
}