test-lib.sh: fix color support when tput needs ~/.terminfo

If tput needs ~/.terminfo for the current $TERM, then tput will
succeed before HOME is changed to $TRASH_DIRECTORY (causing color to
be set to 't') but fail afterward.

One possible way to fix this is to treat HOME like TERM: back up the
original value and temporarily restore it before say_color() runs
tput.

Instead, pre-compute and save the color control sequences before
changing either TERM or HOME.  Use the saved control sequences in
say_color() rather than call tput each time.  This avoids the need to
back up and restore the TERM and HOME variables, and it avoids the
overhead of a subshell and two invocations of tput per call to
say_color().

Signed-off-by: Richard Hansen <rhansen@bbn.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/test-lib.sh

@@ -15,9 +15,6 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see http://www.gnu.org/licenses/ .
 
-# Keep the original TERM for say_color
-ORIGINAL_TERM=$TERM
-
 # Test the binaries we have just built.  The tests are kept in
 # t/ subdirectory and are run in 'trash directory' subdirectory.
 if test -z "$TEST_DIRECTORY"
@@ -68,12 +65,12 @@ done,*)
 esac
 
 # For repeatability, reset the environment to known value.
+# TERM is sanitized below, after saving color control sequences.
 LANG=C
 LC_ALL=C
 PAGER=cat
 TZ=UTC
-TERM=dumb
-export LANG LC_ALL PAGER TERM TZ
+export LANG LC_ALL PAGER TZ
 EDITOR=:
 # A call to "unset" with no arguments causes at least Solaris 10
 # /usr/xpg4/bin/sh and /bin/ksh to bail out.  So keep the unsets
@@ -184,9 +181,7 @@ export _x05 _x40 _z40 LF u200c
 # This test checks if command xyzzy does the right thing...
 # '
 # . ./test-lib.sh
-test "x$ORIGINAL_TERM" != "xdumb" && (
-		TERM=$ORIGINAL_TERM &&
-		export TERM &&
+test "x$TERM" != "xdumb" && (
 		test -t 1 &&
 		tput bold >/dev/null 2>&1 &&
 		tput setaf 1 >/dev/null 2>&1 &&
@@ -260,29 +255,30 @@ fi
 
 if test -n "$color"
 then
+	# Save the color control sequences now rather than run tput
+	# each time say_color() is called.  This is done for two
+	# reasons:
+	#   * TERM will be changed to dumb
+	#   * HOME will be changed to a temporary directory and tput
+	#     might need to read ~/.terminfo from the original HOME
+	#     directory to get the control sequences
+	# Note:  This approach assumes the control sequences don't end
+	# in a newline for any terminal of interest (command
+	# substitutions strip trailing newlines).  Given that most
+	# (all?) terminals in common use are related to ECMA-48, this
+	# shouldn't be a problem.
+	say_color_error=$(tput bold; tput setaf 1) # bold red
+	say_color_skip=$(tput setaf 4) # blue
+	say_color_warn=$(tput setaf 3) # brown/yellow
+	say_color_pass=$(tput setaf 2) # green
+	say_color_info=$(tput setaf 6) # cyan
+	say_color_reset=$(tput sgr0)
+	say_color_="" # no formatting for normal text
 	say_color () {
-		(
-		TERM=$ORIGINAL_TERM
-		export TERM
-		case "$1" in
-		error)
-			tput bold; tput setaf 1;; # bold red
-		skip)
-			tput setaf 4;; # blue
-		warn)
-			tput setaf 3;; # brown/yellow
-		pass)
-			tput setaf 2;; # green
-		info)
-			tput setaf 6;; # cyan
-		*)
-			test -n "$quiet" && return;;
-		esac
+		test -z "$1" && test -n "$quiet" && return
+		eval "say_color_color=\$say_color_$1"
 		shift
-		printf "%s" "$*"
-		tput sgr0
-		echo
-		)
+		printf "%s\\n" "$say_color_color$*$say_color_reset"
 	}
 else
 	say_color() {
@@ -292,6 +288,9 @@ else
 	}
 fi
 
+TERM=dumb
+export TERM
+
 error () {
 	say_color error "error: $*"
 	GIT_EXIT_OK=t