linux_kernel/tools/testing/selftests/sysctl/run_stringtests

#!/bin/sh

SYSCTL="/proc/sys"
TARGET="${SYSCTL}/kernel/domainname"
ORIG=$(cat "${TARGET}")
TEST_STR="Testing sysctl"

. ./common_tests

# Only string sysctls support seeking/appending.
MAXLEN=65

echo -n "Writing entire sysctl in short writes ... "
set_orig
dd if="${TEST_FILE}" of="${TARGET}" bs=1 2>/dev/null
if ! verify "${TARGET}"; then
	echo "FAIL" >&2
	rc=1
else
	echo "ok"
fi

echo -n "Writing middle of sysctl after unsynchronized seek ... "
set_test
dd if="${TEST_FILE}" of="${TARGET}" bs=1 seek=1 2>/dev/null
if verify "${TARGET}"; then
	echo "FAIL" >&2
	rc=1
else
	echo "ok"
fi

echo -n "Checking sysctl maxlen is at least $MAXLEN ... "
set_orig
perl -e 'print "A" x ('"${MAXLEN}"'-2), "B";' | \
	dd of="${TARGET}" bs="${MAXLEN}" 2>/dev/null
if ! grep -q B "${TARGET}"; then
	echo "FAIL" >&2
	rc=1
else
	echo "ok"
fi

echo -n "Checking sysctl keeps original string on overflow append ... "
set_orig
perl -e 'print "A" x ('"${MAXLEN}"'-1), "B";' | \
	dd of="${TARGET}" bs=$(( MAXLEN - 1 )) 2>/dev/null
if grep -q B "${TARGET}"; then
	echo "FAIL" >&2
	rc=1
else
	echo "ok"
fi

echo -n "Checking sysctl stays NULL terminated on write ... "
set_orig
perl -e 'print "A" x ('"${MAXLEN}"'-1), "B";' | \
	dd of="${TARGET}" bs="${MAXLEN}" 2>/dev/null
if grep -q B "${TARGET}"; then
	echo "FAIL" >&2
	rc=1
else
	echo "ok"
fi

echo -n "Checking sysctl stays NULL terminated on overwrite ... "
set_orig
perl -e 'print "A" x ('"${MAXLEN}"'-1), "BB";' | \
	dd of="${TARGET}" bs=$(( $MAXLEN + 1 )) 2>/dev/null
if grep -q B "${TARGET}"; then
	echo "FAIL" >&2
	rc=1
else
	echo "ok"
fi

exit $rc