jobs -Z

[Zefram <zefram@xxxxxxxxxxxxxxxxx>]

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This patch attempts to make jobs -Z respectable.  It is documented.
It is forbidden in RESTRICTED mode.  Some cleverness is adapted from
perl, to determine how much argument space can be safely overwritten.
Unused parts of the argument space are zeroed out, to clearly delimit
the data being presented.  Metafication is handled correctly.

I considered changing the mechanism from running this command to assigning
to $0, Perl style, but as $0 acts oddly in functions I decided that
adding even more special behaviour would be a bad idea.  I'd rather not
add yet another special parameter for this.

 -zefram

 *** Doc/Zsh/builtins.yo	1997/03/22 14:32:03	1.12
 --- Doc/Zsh/builtins.yo	1997/03/23 03:13:02
 ***************
 *** 552,558 ****
   integers are not permitted.
   )
   findex(jobs)
 ! item(tt(jobs) [ tt(-dlprs) ] [ var(job) ... ])(
   Lists information about each given job, or all jobs
   if var(job) is omitted.  The tt(-l) flag lists process
   IDs, and the tt(-p) flag lists process groups.
 --- 552,559 ----
   integers are not permitted.
   )
   findex(jobs)
 ! xitem(tt(jobs) [ tt(-dlprs) ] [ var(job) ... ])
 ! item(tt(jobs -Z) var(string))(
   Lists information about each given job, or all jobs
   if var(job) is omitted.  The tt(-l) flag lists process
   IDs, and the tt(-p) flag lists process groups.
 ***************
 *** 561,566 ****
 --- 562,572 ----
   If the tt(-d) flag is given, the directory from which the job was
   started (which may not be the current directory of the job) will also
   be shown.
 + 
 + The tt(-Z) option replaces the shell's argument and environment space with
 + the given string, truncated if necessary to fit.  This will normally be
 + visible in tt(ps) (manref(ps)(1)) listings.  This feature is typically
 + used by daemons, to indicate their state.
   )
   findex(kill)
   cindex(killing jobs)
 *** Doc/Zsh/restricted.yo	1997/03/23 02:39:09	1.3
 --- Doc/Zsh/restricted.yo	1997/03/23 03:14:32
 ***************
 *** 22,27 ****
 --- 22,29 ----
   itemiz(redirecting output to files)
   itemiz(using the tt(exec) builtin command to replace the shell with another
   command)
 + itemiz(using tt(jobs -Z) to overwrite the shell process' argument and
 + environment space)
   itemiz(using the tt(ARGV0) parameter to override tt(argv[0]) for external
   commands)
   itemiz(turning off restricted mode with tt(set +r) or tt(unsetopt
 *** Src/globals.h	1997/03/22 01:55:37	1.37
 --- Src/globals.h	1997/03/23 02:59:12
 ***************
 *** 346,352 ****
    
   EXTERN char *argzero;           /* $0 */
    
 - EXTERN char *hackzero;
   EXTERN char *scriptname;        /* name of script being sourced */
   
   EXTERN long lineno;             /* $LINENO       */
 --- 346,351 ----
 *** Src/init.c	1997/03/22 01:55:38	1.43
 --- Src/init.c	1997/03/23 03:04:06
 ***************
 *** 107,113 ****
       LinkList paramlist;
       int bourne = (emulation == EMULATE_KSH || emulation == EMULATE_SH);
   
 !     hackzero = argzero = *argv++;
       SHIN = 0;
   
       /* There's a bit of trickery with opts[INTERACTIVE] here.  It starts *
 --- 107,113 ----
       LinkList paramlist;
       int bourne = (emulation == EMULATE_KSH || emulation == EMULATE_SH);
   
 !     argzero = *argv++;
       SHIN = 0;
   
       /* There's a bit of trickery with opts[INTERACTIVE] here.  It starts *
 *** Src/jobs.c	1997/03/04 00:25:46	1.16
 --- Src/jobs.c	1997/03/23 03:03:07
 ***************
 *** 933,938 ****
 --- 933,974 ----
       return returnval;
   }
   
 + /* For jobs -Z (which modifies the shell's name as seen in ps listings).  *
 +  * hackzero is the start of the safely writable space, and hackspace is   *
 +  * its length, excluding a final NUL terminator that will always be left. */
 + 
 + static char *hackzero;
 + static int hackspace;
 + 
 + /* Initialise the jobs -Z system.  The technique is borrowed from perl: *
 +  * check through the argument and environment space, to see how many of *
 +  * the strings are in contiguous space.  This determines the value of   *
 +  * hackspace.                                                           */
 + 
 + /**/
 + void
 + init_hackzero(char **argv, char **envp)
 + {
 +     char *p, *q;
 + 
 +     hackzero = *argv;
 +     p = strchr(hackzero, 0);
 +     while(*++argv) {
 + 	q = *argv;
 + 	if(q != p+1)
 + 	    goto done;
 + 	p = strchr(q, 0);
 +     }
 +     for(; *envp; envp++) {
 + 	q = *envp;
 + 	if(q != p+1)
 + 	    goto done;
 + 	p = strchr(q, 0);
 +     }
 +     done:
 +     hackspace = p - hackzero;
 + }
 + 
   /* bg, disown, fg, jobs, wait: most of the job control commands are     *
    * here.  They all take the same type of argument.  Exception: wait can *
    * take a pid or a job specifier, whereas the others only work on jobs. */
 ***************
 *** 944,951 ****
       int job, lng, firstjob = -1, retval = 0;
   
       if (ops['Z']) {
 ! 	if (*argv)
 ! 	    strcpy(hackzero, *argv);
   	return 0;
       }
   
 --- 980,1000 ----
       int job, lng, firstjob = -1, retval = 0;
   
       if (ops['Z']) {
 ! 	int len;
 ! 
 ! 	if(isset(RESTRICTED)) {
 ! 	    zwarnnam(name, "-Z is restricted", NULL, 0);
 ! 	    return 1;
 ! 	}
 ! 	if(!argv[0] || argv[1]) {
 ! 	    zwarnnam(name, "-Z requires one argument", NULL, 0);
 ! 	    return 1;
 ! 	}
 ! 	unmetafy(*argv, &len);
 ! 	if(len > hackspace)
 ! 	    len = hackspace;
 ! 	memcpy(hackzero, *argv, len);
 ! 	memset(hackzero + len, 0, hackspace - len);
   	return 0;
       }
   
 *** Src/main.c	1997/01/29 03:25:18	1.7
 --- Src/main.c	1997/03/23 02:58:57
 ***************
 *** 44,49 ****
 --- 44,51 ----
   
       global_permalloc();
   
 +     init_hackzero(argv, environ);
 + 
       for (t = argv; *t; *t = metafy(*t, -1, META_ALLOC), t++);
   
       if (!(zsh_name = strrchr(argv[0], '/')))

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