util  Check-in [4b7174b913]

Modified xpriv.c from [c67b168cf4] to [afa1600fae].

    34     34    * the command  “xpriv -a”  instead of the  user’s normal
    35     35    * shell. the -a flag instructs xpriv to get the terminal
    36     36    * window’s  ID from  the $WINDOWID  environment variable
    37     37    * which urxvt  sets. after this, a  ssh-agent process is
    38     38    * launched. spriv waits until it has opened a socket and
    39     39    * then runs ssh-add without parameters to add the user's
    40     40    * default keys to the session.
           41  + *
           42  + * after  a success  key-add  has  been confirmed,  xpriv
           43  + * marks the window as “vital”  by setting the X property
           44  + * “_k_vital” on the  window. if the login  fails or does
           45  + * not complete,  safekill.c will  still terminate  it at
           46  + * any time.  the vital  flag is removed  as soon  as the
           47  + * controlling shell terminates; it does *not* remain for
           48  + * the lifetime  of the window, so  a "temporary" session
           49  + * can  be created  in  the current  terminal by  calling
           50  + * `xpriv -a` directly.
    41     51    *
    42     52    * xpriv  does  its  best   to  clean  up  after  itself,
    43     53    * killing all sensitive processes and their children and
    44     54    * removing the  shmem segment  when it  is no  longer in
    45     55    * use, even if exits somewhat abnormally. if you have to
    46     56    * kill -9 xpriv  at any point tho, you can  make it work
    47     57    * again (on linux) with
................................................................................
   304    314   			case 'w': init_weak = true; break;
   305    315   			default: return bad(fail_opt);
   306    316   		}
   307    317   		if(opt[1] != 0) { ++opt; goto read_opt; }
   308    318   	}
   309    319   
   310    320   	size_t nsz;
   311         -	const char* basename, *p;
          321  +	const char* basename = argv[0], *p;
   312    322   	for (p = argv[0]; *p!=0; ++p) {
   313    323   		if(*p == '/') basename = p + 1;
   314    324   	}
   315    325   	nsz = p - basename;
   316    326   	char shid[nsz + sizeof shmem_prefix + 0];
   317    327   	strncpy(shid,shmem_prefix,sizeof shmem_prefix);
   318    328   	strncpy(shid + sizeof shmem_prefix - 1, basename, nsz);