newns/newns.c

   1 /******************************************************************************
   2  * newns.c
   3  * Roughly the same as: http://glandium.org/blog/?p=217
   4  *****************************************************************************/
   5
   6 #include <sched.h>
   7 #include <syscall.h>
   8 #include <unistd.h>
   9 #include <errno.h>
  10 #include <stdlib.h>
  11 #include <stdio.h>
  12 #include <signal.h>
  13 #include <sys/syscall.h>
  14 #include <sys/wait.h>
  15
  16 #include <getopt.h>
  17
  18
  19 void help()
  20 {
  21     fputs("newns: launch a process in a new namespace\n\n" \
  22     "Usage: newns [-0npuUi] [command]\n\n" \
  23     "Options:\n" \
  24     "\t -0\t\treset previous (including default CLONE_NEWNS)\n" \
  25     "\t -n\t\t[CLONE_NEWNS]   new mount namespace; the default\n" \
  26     "\t -p\t\t[CLONE_NEWPID]  new PID namespace\n" \
  27     "\t -U\t\t[CLONE_NEWUTS]  new UTS namespace\n" \
  28     "\t -u\t\t[CLONE_NEWUSER] new USER namespace\n" \
  29     "\t -i\t\t[CLONE_NEWIPC]  new IPC namespace\n\n" \
  30     "Default namespace is mount namespace (CLONE_NEWNS); default command is a new shell (/bin/sh)\n\n" \
  31     , stderr);
  32 }
  33
  34
  35 int main(int argc, char *argv[])
  36 {
  37     int err, c, flag=CLONE_NEWNS;
  38
  39     while( (c = getopt(argc, argv, "0unUiph")) != -1 )
  40     {
  41         switch(c)
  42         {
  43             case '0': flag = 0; break;
  44             case 'n': flag |= CLONE_NEWNS; break;
  45             case 'u': flag |= CLONE_NEWUSER; break;
  46             case 'U': flag |= CLONE_NEWUTS; break;
  47             case 'p': flag |= CLONE_NEWPID; break;
  48             case 'i': flag |= CLONE_NEWIPC; break;
  49             case 'h': help(); exit(0); break;
  50             case '?': help(); exit(1); break;
  51         } /* switch argument */
  52     } /* while getopt() */
  53
  54 #if 0
  55     err = syscall(SYS_unshare, flag);
  56     /* err = unshare(flag); */
  57     if(-1 == err)
  58     {
  59         perror("unshare() failed");
  60         exit(1);
  61     }
  62 #else
  63     err = syscall(SYS_clone, SIGCHLD | flag, NULL);
  64     if(-1 == err)
  65     {
  66         perror("clone() failed");
  67         exit(1);
  68     }
  69     else if(0 != err)
  70     {
  71        wait(NULL);
  72        return 0;
  73     }
  74 #endif
  75
  76     if(optind < argc)
  77         return execvp(argv[optind], &argv[optind]);
  78
  79     return execv("/bin/sh", NULL);
  80 }