[patches] cross-test-ssh.sh improvements

[Daniel Jacobowitz <dan@xxxxxxxxxxxxxxxx>]

This patch was part of another project I was working on; that didn't
work out, but I'm posting this bit in the hopes it will be useful.

TERM, TERMCAP, and PWD are not useful to pass to the remote system.
TERMCAP is particularly annoying since it may contain big blocks of
text, newlines, and even funny characters in some cases.  If you're
using --ssh to specify something other than ssh, your replacement
may have trouble dealing with it - mine did.

Blacklisting TERMCAP turned up that blacklist_exports did not work
for environment variables which contained a newline.

And remove_newlines generates a single command rather than a series of
individual commands; sometimes this is faster.

OK?

-- 
Daniel Jacobowitz
CodeSourcery

2007-08-28  Daniel Jacobowitz  <dan@xxxxxxxxxxxxxxxx>

	* scripts/cross-test-ssh.sh (env_blacklist): Add TERM, TERMCAP, PWD.
	(remove_newlines): New.
	(blacklist_exports): Unset blacklisted variables and use export.
	(Top level): Use remove_newlines.

Index: scripts/cross-test-ssh.sh
===================================================================
--- scripts/cross-test-ssh.sh	(revision 179949)
+++ scripts/cross-test-ssh.sh	(working copy)
@@ -3,7 +3,7 @@
 # Run with --help flag to get more detailed help.
 
 progname="$(basename $0)"
-env_blacklist='HOME LOGNAME MAIL PATH SHELL SHLVL SSH_CLIENT SSH_CONNECTION USER'
+env_blacklist='HOME LOGNAME MAIL PATH SHELL SHLVL SSH_CLIENT SSH_CONNECTION USER TERM TERMCAP PWD'
 
 usage="usage: ${progname} [--ssh SSH] HOST COMMAND ..."
 help="Run an EGLIBC test COMMAND on the remote machine HOST, via ssh,
@@ -87,24 +87,32 @@ bourne_quote () {
     printf '%s' '"'
 }
 
-# Echo all lines of input except those starting with 'export VAR=',
-# where VAR is a blacklisted variable.  Turn lines starting with
-# 'declare -x VAR=' into the analogous export commands, before
-# blacklisting.
+# Remove unnecessary newlines from a Bourne shell command sequence.
+remove_newlines () {
+    sed -n \
+        -e '1h' \
+        -e '2,$H' \
+        -e '${g
+              s/\([^\]\)\n/\1; /g
+              p
+             }'
+}
+
+# Unset all variables from the blacklist.  Then echo all exported
+# variables.  This should be run in a subshell.  The 'export -p'
+# command adds backslashes for environment variables which contain
+# newlines.
 blacklist_exports () {
-    local pat
-    pat="$(for var in ${env_blacklist}; do
-             echo "^export ${var}="
-           done)"
-    sed -e 's|^declare -x |export |' \
-        | grep -v -e "$pat"
+    local var
+    for var in ${env_blacklist}; do
+	unset $var
+    done
+    export -p
 }
 
 # Produce properly quoted Bourne shell arguments for 'env' to carry
 # over the current environment, less blacklisted variables.
-# The 'export -p' command munges the values of environment variables if
-# they contain newlines.
-exports="$(export -p | blacklist_exports)"
+exports="$( (blacklist_exports) | sed -e 's|^declare -x |export |')"
 
 # Transform the current argument list into a properly quoted Bourne shell
 # command string.
@@ -122,4 +130,4 @@ ${command}"
 # passes them to some shell.  We want to force the use of /bin/sh,
 # so we need to re-quote the whole command to ensure it appears as
 # the sole argument of the '-c' option.
-$ssh "$host" /bin/sh -c "$(printf '%s\n' "${command}" | bourne_quote)"
+$ssh "$host" /bin/sh -c "$(printf '%s\n' "${command}" | bourne_quote | remove_newlines)"