makepkg: clean up BUILDSCRIPT usage

FS#15448 (which is made worse by the "fix" for FS#14727...), highlighted
some deficiencies in the usage of the BUILDSCRIPT variable. In particular,
only relative paths worked with "-p" and some output was very strange in
combination with the "-p" flag or reading from /dev/stdin. e.g.
"Please add a license line to your /dev/stdin!".

This patch adds a new variable, BUILDFILE, which contains the full path
to the BUILDSCRIPT.  This defaults to $startdir/$BUILDSCRIPT.

Also, fix a missed quoting of $BUILD{SCRIPT->FILE} and remove warning
about missing BUILDSCRIPT definition in makepkg.conf as the default
BUILDSCRIPT value is now specified during configure. Add check that
BUILDFILE is writable before updating VCS PKGBUILDs. When making a source
package, the BUILDSCRIPT always gets given the default name, regardless
of what it was originally called.

Signed-off-by: Allan McRae <allan@archlinux.org>

scripts/makepkg.sh.in

@@ -1032,7 +1032,7 @@ create_srcpackage() {
 	mkdir "${srclinks}"/${pkgbase}
 
 	msg2 "$(gettext "Adding %s...")" "$BUILDSCRIPT"
-	ln -s "${startdir}/${BUILDSCRIPT}" "${srclinks}/${pkgbase}/"
+	ln -s "${BUILDFILE}" "${srclinks}/${pkgbase}/${BUILDSCRIPT}"
 
 	if [ -n "$install" ]; then
 		if [ -f $install ]; then
@@ -1192,8 +1192,9 @@ devel_check() {
 	newpkgver=""
 
 	# Do not update pkgver if --holdver is set, when building a source package,
-	# or when reading PKGBUILD from pipe
-	if [ "$HOLDVER" -eq 1 -o "$SOURCEONLY" -ne 0 -o ! -f "./$BUILDSCRIPT" ]; then
+	# when reading PKGBUILD from pipe (-f), or if we cannot write to the file (-w)
+	if [ "$HOLDVER" -eq 1 -o "$SOURCEONLY" -ne 0 -o ! -f "$BUILDFILE" \
+	                      -o ! -w "$BUILDFILE" ]; then
 		return
 	fi
 
@@ -1262,10 +1263,10 @@ devel_update() {
 	#
 	if [ -n "$newpkgver" ]; then
 		if [ "$newpkgver" != "$pkgver" ]; then
-			if [ -f "./$BUILDSCRIPT" ]; then
-				@SEDINPLACE@ "s/^pkgver=[^ ]*/pkgver=$newpkgver/" "./$BUILDSCRIPT"
-				@SEDINPLACE@ "s/^pkgrel=[^ ]*/pkgrel=1/" "./$BUILDSCRIPT"
-				source "$BUILDSCRIPT"
+			if [ -f "$BUILDFILE" -a -w "$BUILDFILE" ]; then
+				@SEDINPLACE@ "s/^pkgver=[^ ]*/pkgver=$newpkgver/" "$BUILDFILE"
+				@SEDINPLACE@ "s/^pkgrel=[^ ]*/pkgrel=1/" "$BUILDFILE"
+				source "$BUILDFILE"
 			fi
 		fi
 	fi
@@ -1480,7 +1481,7 @@ while true; do
 		-L|--log)         LOGGING=1 ;;
 		-m|--nocolor)     USE_COLOR='n' ;;
 		-o|--nobuild)     NOBUILD=1 ;;
-		-p)               shift; BUILDSCRIPT=$1 ;;
+		-p)               shift; BUILDFILE=$1 ;;
 		-r|--rmdeps)      RMDEPS=1 ;;
 		-R|--repackage)   REPKG=1 ;;
 		--source)         SOURCEONLY=1 ;;
@@ -1565,11 +1566,6 @@ if [ "$CLEANCACHE" -eq 1 ]; then
 	fi
 fi
 
-if [ -z "$BUILDSCRIPT" ]; then
-	error "$(gettext "BUILDSCRIPT is undefined! Ensure you have updated %s.")" "$MAKEPKG_CONF"
-	exit 1
-fi
-
 if [ "$INFAKEROOT" -eq 0 ]; then
 	if [ $EUID -eq 0 -a "$ASROOT" -eq 0 ]; then
 		# Warn those who like to live dangerously.
@@ -1616,23 +1612,27 @@ unset pkgname pkgbase pkgver pkgrel pkgdesc url license groups provides
 unset md5sums replaces depends conflicts backup source install build
 unset makedepends optdepends options noextract
 
-if [ ! -f "$BUILDSCRIPT" ]; then
+BUILDFILE=${BUILDFILE:-$BUILDSCRIPT}
+if [ ! -f "$BUILDFILE" ]; then
 	if [ -t 0 ]; then
-		error "$(gettext "%s does not exist.")" "$BUILDSCRIPT"
+		error "$(gettext "%s does not exist.")" "$BUILDFILE"
 		exit 1
 	else
 		# PKGBUILD passed through a pipe
-		BUILDSCRIPT=/dev/stdin
-		source "$BUILDSCRIPT"
+		BUILDFILE=/dev/stdin
+		source "$BUILDFILE"
 	fi
 else
-	crlftest=$(file $BUILDSCRIPT | grep -F 'CRLF' || true)
+	crlftest=$(file "$BUILDFILE" | grep -F 'CRLF' || true)
 	if [ -n "$crlftest" ]; then
-		error "$(gettext "%s contains CRLF characters and cannot be sourced.")" "$BUILDSCRIPT"
+		error "$(gettext "%s contains CRLF characters and cannot be sourced.")" "$BUILDFILE"
 		exit 1
 	fi
 
-	source ./"$BUILDSCRIPT"
+	if [ "${BUILDFILE:0:1}" != "/" ]; then
+		BUILDFILE="$startdir/$BUILDFILE"
+	fi
+	source "$BUILDFILE"
 fi
 
 if [ "$GENINTEG" -eq 1 ]; then