detect gl-emergency-addkey attempt for server side installs

and give a suitable message, fix the doc, etc.

(error found by "ry" on #git backlog; couldn't contact him later)

doc/6-ssh-troubleshooting.mkd

@@ -429,8 +429,7 @@ first place, so the simplest way is to enable it from the server side only.
 If you lost the admin key, and need to re-establish ownership of the
 gitolite-admin repository with a fresh key, take a look at the
 `src/gl-emergency-addkey` program.  You will need shell access to the server
-of course.  The top of the script has useful information on how to use it and
-what it needs.
+of course.  Run it without arguments to get instructions.
 
 <a name="simulating_ssh_copy_id"></a>
 

src/gl-emergency-addkey

@@ -1,30 +1,49 @@
 #!/bin/sh
 
-# what/why: re-establish gitolite admin access when admin key(s) lost
-# where:    on server (NOT client!)
+# Use this to re-establish gitolite admin access when admin key(s) are lost.
 
-# pre-req:  shell access to the server (even with password is fine)
-# pre-work:  -  make yourself a new keypair on your workstation
-#            -  copy the pubkey and this script to the server
+# RUN THIS ON THE SERVER, NOT THE CLIENT!  (so you need shell access to the
+# server; even with password is fine)
 
-# usage:    $0 admin_name client_host_shortname pubkeyfile
-# notes:     -  admin_name should already have RW or RW+ access to the
-#               gitolite-admin repo
-#            -  client_host_shortname is any simple word; see example below
+# HOW TO USE (substitute your admin name for "sitaram" below)
+# - make yourself a new keypair on your workstation
+# - copy the pubkey to the server, call it "sitaram.pub" and put it in $HOME
+# - run this command:
+#       ~/.gitolite/src/gl-emergency-addkey sitaram emergency sitaram.pub
+
+# this will add a new key called sitaram@emergency.pub.  Since the "userid"
+# that key pertains to is "sitaram", whoever has the private key for this now
+# has the same rights as "sitaram"
 
 # WARNING: ABSOLUTELY NO ARGUMENT CHECKING DONE
 # WARNING: NEWER GITS ONLY ON SERVER SIDE (for now)
 
-# example:  $0 sitaram laptop /tmp/sitaram.pub
-# result:   a new keyfile named sitaram@laptop.pub would be added
-
 # ENDHELP
 
+# we can't use this program unless it was installed using gl-easy-install
+GL_PACKAGE_CONF=$( cd; perl -e 'do ".gitolite.rc"; print $GL_PACKAGE_CONF' )
+if [ -n "$GL_PACKAGE_CONF" ]
+then
+    cat <<EOF
+    This is not a "from-client method" install; you cannot add an emergency
+    key using this program.
+
+    Please do the following (change "sitaram" below to whatever your admin
+    username is):
+
+      - get your *new* public key to the server
+      - call it "sitaram.pub"; put it in \$HOME
+      - run "gl-setup \$HOME/sitaram.pub"
+EOF
+    exit 1
+fi
+
 [ -z "$1" ] && { perl -pe "s(\\\$0)($0); last if /ENDHELP/" < $0; exit 1; }
 
 set -e
 
 cd
+
 REPO_BASE=$(  perl -e 'do ".gitolite.rc"; print $REPO_BASE'  )
 GL_ADMINDIR=$(perl -e 'do ".gitolite.rc"; print $GL_ADMINDIR')