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fat: Add KUnit tests for checksums and timestamps 
Add some basic sanity-check tests for the fat_checksum() function and
the fat_time_unix2fat() and fat_time_fat2unix() functions. These unit
tests verify these functions return correct output for a number of test
inputs.

These tests were inspored by -- and serve a similar purpose to -- the
timestamp parsing KUnit tests in ext4[1].

[1]:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/ext4/inode-test.c

Signed-off-by: David Gow <davidgow@google.com>
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@sulix @intel-lab-lkp
sulix authored and intel-lab-lkp committed Oct 17, 2020
1 parent 071a057 commit 318413ec0ade19d4570ae13fc42afb289246d50f
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13 fs/fat/Kconfig
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@@ -115,3 +115,16 @@ config FAT_DEFAULT_UTF8
Say Y if you use UTF-8 encoding for file names, N otherwise.

See <file:Documentation/filesystems/vfat.rst> for more information.

config FAT_KUNIT_TEST
tristate "Unit Tests for FAT filesystems" if !KUNIT_ALL_TESTS
select FAT_FS
depends on KUNIT
default KUNIT_ALL_TESTS
help
This builds the FAT KUnit tests

For more information on KUnit and unit tests in general, please refer
to the KUnit documentation in Documentation/dev-tools/kunit

If unsure, say N
2 fs/fat/Makefile
View file
@@ -10,3 +10,5 @@ obj-$(CONFIG_MSDOS_FS) += msdos.o
fat-y := cache.o dir.o fatent.o file.o inode.o misc.o nfs.o
vfat-y := namei_vfat.o
msdos-y := namei_msdos.o

obj-$(CONFIG_FAT_KUNIT_TEST) += fat_test.o
197 fs/fat/fat_test.c
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@@ -0,0 +1,197 @@
// SPDX-License-Identifier: GPL-2.0
/*
* KUnit tests for FAT filesystems.
*
* Copyright (C) 2020 Google LLC.
* Author: David Gow <davidgow@google.com>
*/

#include <kunit/test.h>

#include "fat.h"

static void fat_checksum_test(struct kunit *test)
{
/* With no extension. */
KUNIT_EXPECT_EQ(test, fat_checksum("VMLINUX "), 44);
/* With 3-letter extension. */
KUNIT_EXPECT_EQ(test, fat_checksum("README TXT"), 115);
/* With short (1-letter) extension. */
KUNIT_EXPECT_EQ(test, fat_checksum("ABCDEFGHA "), 98);
}


struct fat_timestamp_testcase {
const char *name;
struct timespec64 ts;
__le16 time;
__le16 date;
u8 cs;
int time_offset;
};

const static struct fat_timestamp_testcase time_test_cases[] = {
{
.name = "Earliest possible UTC (1980-01-01 00:00:00)",
.ts = {.tv_sec = 315532800LL, .tv_nsec = 0L},
.time = 0,
.date = 33,
.cs = 0,
.time_offset = 0,
},
{
.name = "Latest possible UTC (2107-12-31 23:59:58)",
.ts = {.tv_sec = 4354819198LL, .tv_nsec = 0L},
.time = 49021,
.date = 65439,
.cs = 0,
.time_offset = 0,
},
{
.name = "Earliest possible (UTC-11) (== 1979-12-31 13:00:00 UTC)",
.ts = {.tv_sec = 315493200LL, .tv_nsec = 0L},
.time = 0,
.date = 33,
.cs = 0,
.time_offset = 11 * 60,
},
{
.name = "Latest possible (UTC+11) (== 2108-01-01 10:59:58 UTC)",
.ts = {.tv_sec = 4354858798LL, .tv_nsec = 0L},
.time = 49021,
.date = 65439,
.cs = 0,
.time_offset = -11 * 60,
},
{
.name = "Leap Day / Year (1996-02-29 00:00:00)",
.ts = {.tv_sec = 825552000LL, .tv_nsec = 0L},
.time = 0,
.date = 8285,
.cs = 0,
.time_offset = 0,
},
{
.name = "Year 2000 is leap year (2000-02-29 00:00:00)",
.ts = {.tv_sec = 951782400LL, .tv_nsec = 0L},
.time = 0,
.date = 10333,
.cs = 0,
.time_offset = 0,
},
{
.name = "Year 2100 not leap year (2100-03-01 00:00:00)",
.ts = {.tv_sec = 4107542400LL, .tv_nsec = 0L},
.time = 0,
.date = 61537,
.cs = 0,
.time_offset = 0,
},
{
.name = "Leap year + timezone UTC+1 (== 2004-02-29 00:30:00 UTC)",
.ts = {.tv_sec = 1078014600LL, .tv_nsec = 0L},
.time = 48064,
.date = 12380,
.cs = 0,
.time_offset = -60,
},
{
.name = "Leap year + timezone UTC-1 (== 2004-02-29 23:30:00 UTC)",
.ts = {.tv_sec = 1078097400LL, .tv_nsec = 0L},
.time = 960,
.date = 12385,
.cs = 0,
.time_offset = 60,
},
{
.name = "VFAT odd-second resolution (1999-12-31 23:59:59)",
.ts = {.tv_sec = 946684799LL, .tv_nsec = 0L},
.time = 49021,
.date = 10143,
.cs = 100,
.time_offset = 0,
},
{
.name = "VFAT 10ms resolution (1980-01-01 00:00:00:0010)",
.ts = {.tv_sec = 315532800LL, .tv_nsec = 10000000L},
.time = 0,
.date = 33,
.cs = 1,
.time_offset = 0,
},
};

static void fat_time_fat2unix_test(struct kunit *test)
{
struct msdos_sb_info fake_sb;
int i;
struct timespec64 ts;

for (i = 0; i < ARRAY_SIZE(time_test_cases); ++i) {
fake_sb.options.tz_set = 1;
fake_sb.options.time_offset = time_test_cases[i].time_offset;

fat_time_fat2unix(&fake_sb, &ts,
time_test_cases[i].time,
time_test_cases[i].date,
time_test_cases[i].cs);
KUNIT_EXPECT_EQ_MSG(test,
time_test_cases[i].ts.tv_sec,
ts.tv_sec,
"Timestamp mismatch (seconds) in case \"%s\"\n",
time_test_cases[i].name);
KUNIT_EXPECT_EQ_MSG(test,
time_test_cases[i].ts.tv_nsec,
ts.tv_nsec,
"Timestamp mismatch (nanoseconds) in case \"%s\"\n",
time_test_cases[i].name);
}
}

static void fat_time_unix2fat_test(struct kunit *test)
{
struct msdos_sb_info fake_sb;
int i;
__le16 date, time;
u8 cs;

for (i = 0; i < ARRAY_SIZE(time_test_cases); ++i) {
fake_sb.options.tz_set = 1;
fake_sb.options.time_offset = time_test_cases[i].time_offset;

fat_time_unix2fat(&fake_sb, &time_test_cases[i].ts,
&time, &date, &cs);
KUNIT_EXPECT_EQ_MSG(test,
time_test_cases[i].time,
time,
"Time mismatch in case \"%s\"\n",
time_test_cases[i].name);
KUNIT_EXPECT_EQ_MSG(test,
time_test_cases[i].date,
date,
"Date mismatch in case \"%s\"\n",
time_test_cases[i].name);
KUNIT_EXPECT_EQ_MSG(test,
time_test_cases[i].cs,
cs,
"Centisecond mismatch in case \"%s\"\n",
time_test_cases[i].name);
}
}

static struct kunit_case fat_test_cases[] = {
KUNIT_CASE(fat_checksum_test),
KUNIT_CASE(fat_time_fat2unix_test),
KUNIT_CASE(fat_time_unix2fat_test),
{},
};

static struct kunit_suite fat_test_suite = {
.name = "fat_test",
.test_cases = fat_test_cases,
};

kunit_test_suites(&fat_test_suite);

MODULE_LICENSE("GPL v2");

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