Re: Job table full

[Peter Stephenson <pws@csr.com>]

Wayne Davison wrote:
> On Wed, May 12, 2004 at 02:40:29PM +0100, Peter Stephenson wrote:
> > A reliable way of reproducing it would help.
> 
> It's pretty easy:
> 
>     zsh -f
>     preexec() { x=`echo hi` }
>     sleep 1 &
>     :              [execute any 20 commands]
> 
> The problem appears to be that, after the job-control run, the value of
> "thisjob" in the preexec() function becomes -1.  This comparison then
> fails due to a signed/unsigned mismatch:
> 
>     if (thisjob >= jobtabsize - 1 && !expandjobtab()) {

Aha.  That's good.

thisjob is allowed to be -1, it simply means there's no valid
current job.  So the-test-that-no-one-understands should simply have
`thisjob != -1' in it, as in other places in the code.

Here is a fix with some other paranoid tests for thisjob when debugging
is turned on.

Index: Src/exec.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/exec.c,v
retrieving revision 1.62
diff -u -r1.62 exec.c
--- Src/exec.c	21 May 2004 11:19:30 -0000	1.62
+++ Src/exec.c	25 May 2004 18:18:06 -0000
@@ -219,7 +219,7 @@
     /*
      * Is anybody willing to explain this test?
      */
-    if (thisjob >= jobtabsize - 1 && !expandjobtab()) {
+    if (thisjob != -1 && thisjob >= jobtabsize - 1 && !expandjobtab()) {
 	zerr("job table full", NULL, 0);
 	return -1;
     }
Index: Src/jobs.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/jobs.c,v
retrieving revision 1.28
diff -u -r1.28 jobs.c
--- Src/jobs.c	2 May 2004 19:55:58 -0000	1.28
+++ Src/jobs.c	25 May 2004 18:18:07 -0000
@@ -904,6 +904,7 @@
     Process pn, *pnlist;
     struct timezone dummy_tz;
 
+    DPUTS(thisjob == -1, "No valid job in addproc.");
     pn = (Process) zshcalloc(sizeof *pn);
     pn->pid = pid;
     if (text)
@@ -1035,6 +1036,7 @@
 waitjobs(void)
 {
     Job jn = jobtab + thisjob;
+    DPUTS(thisjob == -1, "No valid job in waitjobs.");
 
     if (jn->procs || jn->auxprocs)
 	zwaitjob(thisjob, 0);
@@ -1129,6 +1131,7 @@
 {
     Process pn;
 
+    DPUTS(thisjob == -1, "No valid job in spawnjob.");
     /* if we are not in a subshell */
     if (!subsh) {
 	if (curjob == -1 || !(jobtab[curjob].stat & STAT_STOPPED)) {

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR Ltd., Science Park, Milton Road,
Cambridge, CB4 0WH, UK                          Tel: +44 (0)1223 692070


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