Re: [PATCH/RFC] eradicate bashisms in scripts/patch-kernel

[Andreas Mohr <andi@lisas.de>]

Hi,

On Thu, Nov 01, 2007 at 08:24:57AM -0700, Randy Dunlap wrote:
> On Thu, 1 Nov 2007 13:11:33 +0100 Andreas Mohr wrote:
> > I'll think a bit more about these couple changed places (and whether
> > this still truly works as intended) and mail a patch then.
> > 
> > (and a big NOTE: I'm no POSIX vs. non-POSIX shell guru at all, only a
> > semi-versed shell script writer, thus these changes should be reviewed
> > quite thoroughly)
> 
> Neither am I.  I read those web pages quickly yesterday, so after
> you read them, we can discuss more and/or review more patches.

OK, next iteration (v2).


Make the patch-kernel shell script sufficiently compatible with POSIX shells.


Changes since v1:
- don't actually change string quoting
- prepend ./ at mktemp step already
- remove added superfluous spaces in arithmetic expression
- don't remove double braces in STOPSUBLEVEL evaluation,
  since these are integer values to be compared

Full ChangeLog:
- replaced non-standard "==" by standard "="
- replaced non-standard "source" statement by POSIX "dot" statement
- POSIX shell local file lookup needs ./ prepended, thus have mktemp
  use this from the beginning and comment it properly
- replace non-standard bash string parsing by sed expression
  (is the sed syntax ok? correct? strict enough?)
- added missing $ signs to shell variable names

About the missing $ signs:
http://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html#tag_02_14
says:
"If the shell variable x contains a value that forms a valid integer
constant, then the arithmetic expansions
 "$((x))" and "$(($x))" shall return the same value."

Hmm, well, seems dash doesn't... (syntax error).
Thus I still needed to add the $ signs despite opengroup.org specifying
it differently.


Updated version verified again to now work with both bash and dash
on Debian stable.

Patch intended for inclusion in -mm, once it has survived some reviews.

Thanks.

Signed-off-by: Andreas Mohr <andi@lisas.de>

--- linux-2.6.23/scripts/patch-kernel.orig	2007-11-01 22:51:34.000000000 +0100
+++ linux-2.6.23/scripts/patch-kernel	2007-11-01 22:10:14.000000000 +0100
@@ -65,7 +65,7 @@
 patchdir=${2-.}
 stopvers=${3-default}
 
-if [ "$1" == -h -o "$1" == --help -o ! -r "$sourcedir/Makefile" ]; then
+if [ "$1" = -h -o "$1" = --help -o ! -r "$sourcedir/Makefile" ]; then
 cat << USAGE
 usage: $PNAME [-h] [ sourcedir [ patchdir [ stopversion ] [ -acxx ] ] ]
   source directory defaults to /usr/src/linux,
@@ -182,10 +182,12 @@
 }
 
 # set current VERSION, PATCHLEVEL, SUBLEVEL, EXTRAVERSION
-TMPFILE=`mktemp .tmpver.XXXXXX` || { echo "cannot make temp file" ; exit 1; }
+# sourcing $TMPFILE.1 below needs lookup in local directory in a POSIX shell,
+# thus prepend ./ to mktemp argument
+TMPFILE=`mktemp ./.tmpver.XXXXXX` || { echo "cannot make temp file" ; exit 1; }
 grep -E "^(VERSION|PATCHLEVEL|SUBLEVEL|EXTRAVERSION)" $sourcedir/Makefile > $TMPFILE
 tr -d [:blank:] < $TMPFILE > $TMPFILE.1
-source $TMPFILE.1
+. $TMPFILE.1
 rm -f $TMPFILE*
 if [ -z "$VERSION" -o -z "$PATCHLEVEL" -o -z "$SUBLEVEL" ]
 then
@@ -202,13 +204,7 @@
 EXTRAVER=
 if [ x$EXTRAVERSION != "x" ]
 then
-	if [ ${EXTRAVERSION:0:1} == "." ]; then
-		EXTRAVER=${EXTRAVERSION:1}
-	else
-		EXTRAVER=$EXTRAVERSION
-	fi
-	EXTRAVER=${EXTRAVER%%[[:punct:]]*}
-	#echo "$PNAME: changing EXTRAVERSION from $EXTRAVERSION to $EXTRAVER"
+	EXTRAVER=`echo $EXTRAVERSION|sed -s 's/^[\.]\?\([^[:punct:]]*\).*/\1/'`
 fi
 
 #echo "stopvers=$stopvers"
@@ -251,16 +247,16 @@
 do
     CURRENTFULLVERSION="$VERSION.$PATCHLEVEL.$SUBLEVEL"
     EXTRAVER=
-    if [ $stopvers == $CURRENTFULLVERSION ]; then
+    if [ $stopvers = $CURRENTFULLVERSION ]; then
         echo "Stopping at $CURRENTFULLVERSION base as requested."
         break
     fi
 
-    SUBLEVEL=$((SUBLEVEL + 1))
+    SUBLEVEL=$(($SUBLEVEL + 1))
     FULLVERSION="$VERSION.$PATCHLEVEL.$SUBLEVEL"
     #echo "#___ trying $FULLVERSION ___"
 
-    if [ $((SUBLEVEL)) -gt $((STOPSUBLEVEL)) ]; then
+    if [ $(($SUBLEVEL)) -gt $(($STOPSUBLEVEL)) ]; then
 	echo "Stopping since sublevel ($SUBLEVEL) is beyond stop-sublevel ($STOPSUBLEVEL)"
 	exit 1
     fi
@@ -297,7 +293,7 @@
 if [ x$gotac != x ]; then
   # Out great user wants the -ac patches
 	# They could have done -ac (get latest) or -acxx where xx=version they want
-	if [ $gotac == "-ac" ]; then
+	if [ $gotac = "-ac" ]; then
 	  # They want the latest version
 		HIGHESTPATCH=0
 		for PATCHNAMES in $patchdir/patch-${CURRENTFULLVERSION}-ac*\.*
-
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