#include <stdio.h>
#include <stdlib.h>

struct _uname {
  char sysname[65];
  char nodename[65];
  char release[65];
  char version[65];
  char machine[65];
  char domainname[65];
} this_uname;

extern int uname(struct _uname *);
int length(char *);
char *opts(int, char **, char *);
typedef void (*CPUID)(char *);

int main(int argc, char *argv[]) {
  char vendor[13], *f;
  unsigned char cpuid[] = {0xc8, 0x04, 0x00, 0x00, 0x56, 0x8b, 0x75, 0x08,
			   0x31, 0xc0, 0x0f, 0xa2, 0x89, 0x1e, 0x89, 0x56,
   /* just don't ask! */   0x04, 0x89, 0x4e, 0x08, 0xc6, 0x46, 0x0c, 0x00,
			   0x5e, 0xC9, 0xC3};
  int s, n, r, v, m, c, h;
  CPUID cpuidf = (CPUID) cpuid;

  s = n = r = v = m = c = h = 0;

  if (uname(&this_uname) != 0) return 1;
  if ((f = opts(argc, argv, "snrvmcah")))
    for (; *f; f++)
      switch(*f) {
        case 's': s = 1; break;
        case 'n': n = 1; break;
        case 'r': r = 1; break;
        case 'v': v = 1; break;
        case 'm': m = 1; break;
        case 'c': c = 1; break;
        case 'a': s = n = r = v = m = c = 1; break;
        case 'h': h = 1; break;
        default: h = 1;
      }
  else s = 1;

  if (h) {
    printf("usage: %s [-snrvmcah]\n\t-s\tOS name\n\t-n\tnetwork node name\n\t-r\tOS release\n\t-v\tOS version\n\t-m\tmachine type\n\t-c\tcpu name\n\t-a\tall information\n\t-h\tthis help\n", argv[0]);
    return 0;
  }

  (s) ? printf("%s ", this_uname.sysname) :0;
  (n) ? printf("%s ", this_uname.nodename):0;
  (r) ? printf("%s ", this_uname.release) :0;
  (v) ? printf("%s ", this_uname.version) :0;
  (m) ? printf("%s ", this_uname.machine) :0;
  (c) ? cpuidf(vendor), printf(vendor)    :0;
  printf("\n");
  return 0;
}

int length(char *s) {
  int l = 0;
  while (*s) l++, s++;

  return l;
}

char *opts(int argc, char *argv[], char *o) {
  int i, z, j = 0, l = length(o);
  char *buffer = malloc(1024);

  if (argc < 2) return 0;
  for (i=1; i<argc; i++) {
    if (*argv[i] != '-') continue;
    for (; *argv[i]; (argv[i])++)
      for(z=0; z<l; z++)
        if (o[z] == *argv[i]) buffer[j] = *argv[i], j++;
  }

  buffer[j] = '\0';

  return (j) ? buffer : 0;
}