31141: Tighten NO_CLOBBER restrictions on {fd} syntax

to apply only if $fd is exactly an fd and nothing else.

ChangeLog

@@ -1,3 +1,9 @@
+2013-03-10  Peter Stephenson  <p.w.stephenson@ntlworld.com>
+
+	* 31141: Src/exec.c, Test/A04redirect.ztst: NO_CLOBBER for {fd}
+	syntax should only apply if $fd is exactly an fd and nothing
+	else.
+
 2013-03-10  Mikael Magnusson  <mikachu@gmail.com>
 
 	* 30496: Src/prompt.c: Parse argument to %F and %K as prompt
@@ -577,5 +583,5 @@
 
 *****************************************************
 * This is used by the shell to define $ZSH_PATCHLEVEL
-* $Revision: 1.5816 $
+* $Revision: 1.5817 $
 *****************************************************

Src/exec.c

@@ -1885,7 +1885,14 @@ checkclobberparam(struct redir *f)
 	return 0;
     }
 
-    if (!isset(CLOBBER) && (fd = (int)getintvalue(v)) &&
+    /*
+     * We can't clobber the value in the parameter if it's
+     * already an opened file descriptor --- that means it's a decimal
+     * integer corresponding to an opened file descriptor,
+     * not merely an expression that evaluates to a file descriptor.
+     */
+    if (!isset(CLOBBER) && (s = getstrvalue(v)) &&
+	(fd = (int)zstrtol(s, &s, 10)) >= 0 && !*s &&
 	fd <= max_zsh_fd && fdtable[fd] == FDT_EXTERNAL) {
 	zwarn("can't clobber parameter %s containing file descriptor %d",
 	     f->varid, fd);

Test/A04redirect.ztst

@@ -328,6 +328,17 @@
 1q:NO_CLOBBER prevents overwriting parameter with allocated fd
 ?(eval):4: can't clobber parameter myfd containing file descriptor $myfd
 
+  (setopt noclobber
+   exec {myfd}>logfile2b
+   print First open >&$myfd
+   rm -f logfile2b # prevent normal file no_clobberation
+   myotherfd="${myfd}+0"
+   exec {myotherfd}>logfile2b
+   print Overwritten >&$myotherfd)
+   cat logfile2b
+0:NO_CLOBBER doesn't complain about any other expression
+>Overwritten
+
   (exec {myfd}>logfile4
   echo $myfd
   exec {myfd}>&-