Fix memory leak regression tests by using ps(1) (#50)

src/cmd/ksh93/tests/leaks.sh:
- This script was never actually running the regression
  tests because 'vmstate' isn't available as a builtin.
  While this can be fixed by adding vmstate to the builtin
  table, that has the downside of increasing the binary
  size of ksh. This commit replaces all usage of 'vmstate'
  with 'ps' and 'awk' as a different way to measure
  memory usage. The memory leaks regression tests are now
  always run.
- Rename old $n to $N due to new $n interfering with the old
  regression test.
- Add before and after results for the number of 1024-byte
  blocks leaked in each test.

Co-authored-by: Martijn Dekker <martijn@inlv.org>

src/cmd/ksh93/tests/leaks.sh

@@ -17,7 +17,6 @@
 #                  David Korn <dgk@research.att.com>                   #
 #                                                                      #
 ########################################################################
-builtin vmstate 2>/dev/null || exit 0
 
 function err_exit
 {
@@ -30,32 +29,40 @@ alias err_exit='err_exit $LINENO'
 Command=${0##*/}
 integer Errors=0
 
+# Get the current amount of memory usage
+function getmem
+{
+	UNIX95=1 ps -p "$$" -o vsz=
+}
+n=$(getmem)
+if	! let "$n == $n" 2>/dev/null	# not a number?
+then	err\_exit "$LINENO" "'ps' not POSIX-compliant; skipping tests"
+	exit 0
+fi
+
 # test for variable reset leak #
 
 function test_reset
 {
-	integer i n=$1
+	integer i N=$1
 
-	for ((i = 0; i < n; i++))
+	for ((i = 0; i < N; i++))
 	do	u=$i
 	done
 }
 
-n=1000
+N=1000
 
 # one round to get to steady state -- sensitive to -x
 
-test_reset $n
-a=0$(vmstate --format='+%(size)u')
-b=0$(vmstate --format='+%(size)u')
+test_reset $N
+test_reset $N
+before=$(getmem)
+test_reset $N
+after=$(getmem)
 
-test_reset $n
-a=0$(vmstate --format='+%(size)u')
-test_reset $n
-b=0$(vmstate --format='+%(size)u')
-
-if	(( b > a ))
-then	err_exit "variable value reset memory leak -- $((b-a)) bytes after $n iterations"
+if	(( after > before ))
+then	err_exit "variable value reset memory leak -- $((after - before)) KiB after $N iterations"
 fi
 
 # buffer boundary tests
@@ -67,21 +74,21 @@ done
 
 data="(v=;sid=;di=;hi=;ti='1328244300';lv='o';id='172.3.161.178';var=(k='conn_num._total';u=;fr=;l='Number of Connections';n='22';t='number';))"
 read -C stat <<< "$data"
-a=0$(vmstate --format='+%(size)u')
+before=$(getmem)
 for ((i=0; i < 500; i++))
 do	print -r -- "$data"
 done |	while read -u$n -C stat
 	do	:
 	done	{n}<&0-
-b=0$(vmstate --format='+%(size)u')
-(( b > a )) && err_exit 'memory leak with read -C when deleting compound variable'
+after=$(getmem)
+(( after > before )) && err_exit "memory leak with read -C when deleting compound variable (leaked $((after - before)) KiB)"
 
 read -C stat <<< "$data"
-a=0$(vmstate --format='+%(size)u')
+before=$(getmem)
 for ((i=0; i < 500; i++))
 do      read -C stat <<< "$data"
 done
-b=0$(vmstate --format='+%(size)u')
-(( b > a )) && err_exit 'memory leak with read -C when using <<<'
+after=$(getmem)
+(( after > before )) && err_exit "memory leak with read -C when using <<< (leaked $((after - before)) KiB)"
 
 exit $((Errors<125?Errors:125))