Protect scripted Porcelains from GREP_OPTIONS insanity

If the user has exported the GREP_OPTIONS environment variable, the output
from "grep" and "egrep" in scripted Porcelains may be different from what
they expect.  For example, we may want to count number of matching lines,
by "grep" piped to "wc -l", and GREP_OPTIONS=-C3 will break such use.

The approach taken by this change to address this issue is to protect only
our own use of grep/egrep.  Because we do not unset it at the beginning of
our scripts, hook scripts run from the scripted Porcelains are exposed to
the same insanity this environment variable causes when grep/egrep is used
to implement logic (e.g. "grep | wc -l"), and it is entirely up to the
hook scripts to protect themselves.

On the other hand, applypatch-msg hook may want to show offending words in
the proposed commit log message using grep to the end user, and the user
might want to set GREP_OPTIONS=--color to paint the match more visibly.
The approach to protect only our own use without unsetting the environment
variable globally will allow this use case.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-am.sh

@@ -205,7 +205,7 @@ check_patch_format () {
 			# and see if it looks like that they all begin with the
 			# header field names...
 			sed -n -e '/^$/q' -e '/^[ 	]/d' -e p "$1" |
-			LC_ALL=C egrep -v '^[!-9;-~]+:' >/dev/null ||
+			sane_egrep -v '^[!-9;-~]+:' >/dev/null ||
 			patch_format=mbox
 		fi
 	} < "$1" || clean_abort
@@ -554,7 +554,7 @@ do
 			stop_here $this
 
 		# skip pine's internal folder data
-		grep '^Author: Mail System Internal Data$' \
+		sane_grep '^Author: Mail System Internal Data$' \
 			<"$dotest"/info >/dev/null &&
 			go_next && continue
 

git-bisect.sh

@@ -393,7 +393,7 @@ bisect_run () {
 
       cat "$GIT_DIR/BISECT_RUN"
 
-      if grep "first bad commit could be any of" "$GIT_DIR/BISECT_RUN" \
+      if sane_grep "first bad commit could be any of" "$GIT_DIR/BISECT_RUN" \
 		> /dev/null; then
 	  echo >&2 "bisect run cannot continue any more"
 	  exit $res
@@ -405,7 +405,7 @@ bisect_run () {
 	  exit $res
       fi
 
-      if grep "is the first bad commit" "$GIT_DIR/BISECT_RUN" > /dev/null; then
+      if sane_grep "is the first bad commit" "$GIT_DIR/BISECT_RUN" > /dev/null; then
 	  echo "bisect run success"
 	  exit 0;
       fi

git-filter-branch.sh

@@ -457,7 +457,7 @@ if [ "$filter_tag_name" ]; then
 				git mktag) ||
 				die "Could not create new tag object for $ref"
 			if git cat-file tag "$ref" | \
-			   grep '^-----BEGIN PGP SIGNATURE-----' >/dev/null 2>&1
+			   sane_grep '^-----BEGIN PGP SIGNATURE-----' >/dev/null 2>&1
 			then
 				warn "gpg signature stripped from tag object $sha1t"
 			fi

git-instaweb.sh

@@ -41,7 +41,7 @@ resolve_full_httpd () {
 	case "$httpd" in
 	*apache2*|*lighttpd*)
 		# ensure that the apache2/lighttpd command ends with "-f"
-		if ! echo "$httpd" | grep -- '-f *$' >/dev/null 2>&1
+		if ! echo "$httpd" | sane_grep -- '-f *$' >/dev/null 2>&1
 		then
 			httpd="$httpd -f"
 		fi
@@ -297,8 +297,8 @@ EOF
 
 	# check to see if Dennis Stosberg's mod_perl compatibility patch
 	# (<20060621130708.Gcbc6e5c@leonov.stosberg.net>) has been applied
-	if test -f "$module_path/mod_perl.so" && grep 'MOD_PERL' \
-				"$GIT_DIR/gitweb/gitweb.cgi" >/dev/null
+	if test -f "$module_path/mod_perl.so" &&
+	   sane_grep 'MOD_PERL' "$GIT_DIR/gitweb/gitweb.cgi" >/dev/null
 	then
 		# favor mod_perl if available
 		cat >> "$conf" <<EOF
@@ -316,7 +316,7 @@ EOF
 		# plain-old CGI
 		resolve_full_httpd
 		list_mods=$(echo "$full_httpd" | sed "s/-f$/-l/")
-		$list_mods | grep 'mod_cgi\.c' >/dev/null 2>&1 || \
+		$list_mods | sane_grep 'mod_cgi\.c' >/dev/null 2>&1 || \
 		echo "LoadModule cgi_module $module_path/mod_cgi.so" >> "$conf"
 		cat >> "$conf" <<EOF
 AddHandler cgi-script .cgi

git-rebase--interactive.sh

@@ -106,8 +106,8 @@ mark_action_done () {
 	sed -e 1q < "$TODO" >> "$DONE"
 	sed -e 1d < "$TODO" >> "$TODO".new
 	mv -f "$TODO".new "$TODO"
-	count=$(grep -c '^[^#]' < "$DONE")
-	total=$(($count+$(grep -c '^[^#]' < "$TODO")))
+	count=$(sane_grep -c '^[^#]' < "$DONE")
+	total=$(($count+$(sane_grep -c '^[^#]' < "$TODO")))
 	if test "$last_count" != "$count"
 	then
 		last_count=$count
@@ -147,7 +147,7 @@ die_abort () {
 }
 
 has_action () {
-	grep '^[^#]' "$1" >/dev/null
+	sane_grep '^[^#]' "$1" >/dev/null
 }
 
 pick_one () {
@@ -731,7 +731,7 @@ first and then run 'git rebase --continue' again."
 			git rev-list $REVISIONS |
 			while read rev
 			do
-				if test -f "$REWRITTEN"/$rev -a "$(grep "$rev" "$DOTEST"/not-cherry-picks)" = ""
+				if test -f "$REWRITTEN"/$rev -a "$(sane_grep "$rev" "$DOTEST"/not-cherry-picks)" = ""
 				then
 					# Use -f2 because if rev-list is telling us this commit is
 					# not worthwhile, we don't want to track its multiple heads,
@@ -739,7 +739,7 @@ first and then run 'git rebase --continue' again."
 					# be rebasing on top of it
 					git rev-list --parents -1 $rev | cut -d' ' -s -f2 > "$DROPPED"/$rev
 					short=$(git rev-list -1 --abbrev-commit --abbrev=7 $rev)
-					grep -v "^[a-z][a-z]* $short" <"$TODO" > "${TODO}2" ; mv "${TODO}2" "$TODO"
+					sane_grep -v "^[a-z][a-z]* $short" <"$TODO" > "${TODO}2" ; mv "${TODO}2" "$TODO"
 					rm "$REWRITTEN"/$rev
 				fi
 			done

git-rebase.sh

@@ -467,7 +467,7 @@ orig_head=$branch
 mb=$(git merge-base "$onto" "$branch")
 if test "$upstream" = "$onto" && test "$mb" = "$onto" &&
 	# linear history?
-	! (git rev-list --parents "$onto".."$branch" | grep " .* ") > /dev/null
+	! (git rev-list --parents "$onto".."$branch" | sane_grep " .* ") > /dev/null
 then
 	if test -z "$force_rebase"
 	then

git-sh-setup.sh

@@ -114,6 +114,14 @@ git_editor() {
 	eval "${GIT_EDITOR:=vi}" '"$@"'
 }
 
+sane_grep () {
+	GREP_OPTIONS= LC_ALL=C grep "$@"
+}
+
+sane_egrep () {
+	GREP_OPTIONS= LC_ALL=C egrep "$@"
+}
+
 is_bare_repository () {
 	git rev-parse --is-bare-repository
 }

git-submodule.sh

@@ -57,7 +57,7 @@ resolve_relative_url ()
 #
 module_list()
 {
-	git ls-files --error-unmatch --stage -- "$@" | grep '^160000 '
+	git ls-files --error-unmatch --stage -- "$@" | sane_grep '^160000 '
 }
 
 #
@@ -567,7 +567,7 @@ cmd_summary() {
 	cd_to_toplevel
 	# Get modified modules cared by user
 	modules=$(git $diff_cmd $cached --raw $head -- "$@" |
-		egrep '^:([0-7]* )?160000' |
+		sane_egrep '^:([0-7]* )?160000' |
 		while read mod_src mod_dst sha1_src sha1_dst status name
 		do
 			# Always show modules deleted or type-changed (blob<->module)
@@ -581,7 +581,7 @@ cmd_summary() {
 	test -z "$modules" && return
 
 	git $diff_cmd $cached --raw $head -- $modules |
-	egrep '^:([0-7]* )?160000' |
+	sane_egrep '^:([0-7]* )?160000' |
 	cut -c2- |
 	while read mod_src mod_dst sha1_src sha1_dst status name
 	do