short_splice_read.sh

  1#!/bin/sh
  2# SPDX-License-Identifier: GPL-2.0
  3#
  4# Test for mishandling of splice() on pseudofilesystems, which should catch
  5# bugs like 11990a5bd7e5 ("module: Correctly truncate sysfs sections output")
  6#
  7# Since splice fallback was removed as part of the set_fs() rework, many of these
  8# tests expect to fail now. See https://lore.kernel.org/lkml/202009181443.C2179FB@keescook/
  9set -e
 10
 11DIR=$(dirname "$0")
 12
 13ret=0
 14
 15expect_success()
 16{
 17	title="$1"
 18	shift
 19
 20	echo "" >&2
 21	echo "$title ..." >&2
 22
 23	set +e
 24	"$@"
 25	rc=$?
 26	set -e
 27
 28	case "$rc" in
 29	0)
 30		echo "ok: $title succeeded" >&2
 31		;;
 32	1)
 33		echo "FAIL: $title should work" >&2
 34		ret=$(( ret + 1 ))
 35		;;
 36	*)
 37		echo "FAIL: something else went wrong" >&2
 38		ret=$(( ret + 1 ))
 39		;;
 40	esac
 41}
 42
 43expect_failure()
 44{
 45	title="$1"
 46	shift
 47
 48	echo "" >&2
 49	echo "$title ..." >&2
 50
 51	set +e
 52	"$@"
 53	rc=$?
 54	set -e
 55
 56	case "$rc" in
 57	0)
 58		echo "FAIL: $title unexpectedly worked" >&2
 59		ret=$(( ret + 1 ))
 60		;;
 61	1)
 62		echo "ok: $title correctly failed" >&2
 63		;;
 64	*)
 65		echo "FAIL: something else went wrong" >&2
 66		ret=$(( ret + 1 ))
 67		;;
 68	esac
 69}
 70
 71do_splice()
 72{
 73	filename="$1"
 74	bytes="$2"
 75	expected="$3"
 76	report="$4"
 77
 78	out=$("$DIR"/splice_read "$filename" "$bytes" | cat)
 79	if [ "$out" = "$expected" ] ; then
 80		echo "      matched $report" >&2
 81		return 0
 82	else
 83		echo "      no match: '$out' vs $report" >&2
 84		return 1
 85	fi
 86}
 87
 88test_splice()
 89{
 90	filename="$1"
 91
 92	echo "  checking $filename ..." >&2
 93
 94	full=$(cat "$filename")
 95	rc=$?
 96	if [ $rc -ne 0 ] ; then
 97		return 2
 98	fi
 99
100	two=$(echo "$full" | grep -m1 . | cut -c-2)
101
102	# Make sure full splice has the same contents as a standard read.
103	echo "    splicing 4096 bytes ..." >&2
104	if ! do_splice "$filename" 4096 "$full" "full read" ; then
105		return 1
106	fi
107
108	# Make sure a partial splice see the first two characters.
109	echo "    splicing 2 bytes ..." >&2
110	if ! do_splice "$filename" 2 "$two" "'$two'" ; then
111		return 1
112	fi
113
114	return 0
115}
116
117### /proc/$pid/ has no splice interface; these should all fail.
118expect_failure "proc_single_open(), seq_read() splice" test_splice /proc/$$/limits
119expect_failure "special open(), seq_read() splice" test_splice /proc/$$/comm
120
121### /proc/sys/ has a splice interface; these should all succeed.
122expect_success "proc_handler: proc_dointvec_minmax() splice" test_splice /proc/sys/fs/nr_open
123expect_success "proc_handler: proc_dostring() splice" test_splice /proc/sys/kernel/modprobe
124expect_success "proc_handler: special read splice" test_splice /proc/sys/kernel/version
125
126### /sys/ has no splice interface; these should all fail.
127if ! [ -d /sys/module/test_module/sections ] ; then
128	expect_success "test_module kernel module load" modprobe test_module
129fi
130expect_success "kernfs attr splice" test_splice /sys/module/test_module/coresize
131expect_success "kernfs binattr splice" test_splice /sys/module/test_module/sections/.init.text
132
133exit $ret