PATCH: compaudit allows owner of executable

[Peter Stephenson <p.w.stephenson@xxxxxxxxxxxx>]

This prevents compaudit failing on the case where the whole of zsh,
executable and function library, has been installed by a non-root user.
If you are running the executable, you necessarily trust whoever owns
it, so there's no point complaining if they also own the completion
files.  We could print a warning message, but it seems way too late for
that.

I couldn't think of a reasonably safe, standard way of finding out who
owns the executable, however.  So I've done it using the /proc file
system.  I've also assumed zstat is available from zsh/stat.
Suggestions for improvements welcome.

Index: Completion/compaudit
===================================================================
RCS file: /cvsroot/zsh/zsh/Completion/compaudit,v
retrieving revision 1.11
diff -p -u -r1.11 compaudit
--- Completion/compaudit	10 Sep 2011 17:09:51 -0000	1.11
+++ Completion/compaudit	30 Jan 2013 21:10:33 -0000
@@ -82,18 +82,31 @@ fi
 
 [[ $_i_fail == use ]] && return 0
 
+# We will always allow files to be owned by root and the owner of the
+# present process.
+local owners="u0u${EUID}"
+
+# If we can find out who owns the executable, we will allow files to
+# be owned by that user, too.  The argument is that if you don't trust
+# the owner of the executable, it's way too late to worry about it now...
+if [[ -e /proc/$$/exe ]] && zmodload -F zsh/stat b:zstat 2>/dev/null; then
+  local -A stathash
+  if zstat -H stathash /proc/$$/exe && [[ $stathash[uid] -ne 0 ]]; then
+    owners+="u${stathash[uid]}"
+  fi
+fi
+
 # We search for:
-# - world/group-writable directories in fpath not owned by root and the user
+# - world/group-writable directories in fpath not owned by $owners
 # - parent-directories of directories in fpath that are world/group-writable
-#   and not owned by root and the user (that would allow someone to put a
+#   and not owned by $owners (that would allow someone to put a
 #   digest file for one of the directories into the parent directory)
-# - digest files for one of the directories in fpath not owned by root and
-#   the user
-# - and for files in directories from fpath not owned by root and the user
+# - digest files for one of the directories in fpath not owned by $owners
+# - and for files in directories from fpath not owned by $owners
 #   (including zwc files)
 
-_i_wdirs=( ${^fpath}(N-f:g+w:,-f:o+w:,-^u0u${EUID})
-           ${^fpath:h}(N-f:g+w:,-f:o+w:,-^u0u${EUID}) )
+_i_wdirs=( ${^fpath}(N-f:g+w:,-f:o+w:,-^${owners})
+           ${^fpath:h}(N-f:g+w:,-f:o+w:,-^${owners}) )
 
 # RedHat Linux "per-user groups" check.  This is tricky, because it's very
 # difficult to tell whether the sysadmin has put someone else into your
@@ -111,7 +124,7 @@ if (( $#_i_wdirs )); then
 
   if [[ $GROUP == $LOGNAME && ( -z $GROUPMEM || $GROUPMEM == $LOGNAME ) ]]
   then
-    _i_wdirs=( ${^_i_wdirs}(N-f:g+w:^g:${GROUP}:,-f:o+w:,-^u0u${EUID}) )
+    _i_wdirs=( ${^_i_wdirs}(N-f:g+w:^g:${GROUP}:,-f:o+w:,-^${owners}) )
   fi
 fi
 
@@ -122,8 +135,8 @@ then
   _i_wdirs=( ${_i_wdirs:#/usr/local/*} ${^_i_ulwdirs}(Nf:g+ws:^g:staff:,f:o+w:,^u0) )
 fi
 
-_i_wdirs=( $_i_wdirs ${^fpath}.zwc^([^_]*|*~)(N-^u0u${EUID}) )
-_i_wfiles=( ${^fpath}/^([^_]*|*~)(N-^u0u${EUID}) )
+_i_wdirs=( $_i_wdirs ${^fpath}.zwc^([^_]*|*~)(N-^${owners}) )
+_i_wfiles=( ${^fpath}/^([^_]*|*~)(N-^${owners}) )
 
 case "${#_i_wdirs}:${#_i_wfiles}" in
 (0:0) _i_q= ;;


-- 
Peter Stephenson <p.w.stephenson@xxxxxxxxxxxx>
Web page now at http://homepage.ntlworld.com/p.w.stephenson/