[PATCH v8] fat: Add KUnit tests for checksums and timestamps

[David Gow]

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].

Note that, unlike fat_time_unix2fat, fat_time_fat2unix wasn't previously
exported, so this patch exports it as well. This is required for the
case where we're building the fat and fat_test as modules.

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

Signed-off-by: David Gow <davi...@google.com>
Acked-by: OGAWA Hirofumi <hiro...@mail.parknet.co.jp>
---

It's been a while, but this hopefully is a final version of the FAT KUnit
patchset. It has a number of changes to keep it up-to-date with current
KUnit standards, notably the use of parameterised tests and the addition
of a '.kunitconfig' file to allow for easy testing. It also fixes an
endianness tagging issue picked up by the kernel test robot under sparse
on pa-risc.

Cheers,
-- David

Changes since v7:
https://lore.kernel.org/linux-kselftest/20201028064631.3...@google.com/
- Make the two timestamp tests parameterised: this means that the KUnit
runtime and tooling are aware of the different testcases (and print a
nice list of them to the TAP log when the test is run).
- Fix some issues sparse picked up with __le32 tagged integers.
- Add an fs/fat/.kunitconfig file which contains all the Kconfig entries
needed to run the test. The test can now be run with:
./tools/testing/kunit/kunit.py run --kunitconfig fs/fat/.kunitconfig

Changes since v6:
https://lore.kernel.org/linux-kselftest/20201024060558.2...@google.com/
- Make CONFIG_FAT_DEFAULT_CODEPAGE depend on FAT_FS, rather than either
VFAT_FS or MSDOS_FS.
- This means that FAT_KUNIT_TEST can now also just depend of FAT_FS
- Fix a few warnings that KUnit tool was eating:
- KUnit's type checking needs a specific cast for the fat_checksum()
expected results.
- The time test cases shouldn't be 'const'
- The fake superblock is now static, as otherwise it increased the
stack size too much.

Changes since v4/5:
https://lore.kernel.org/linux-kselftest/20201024052047.2...@google.com/
- Fix a typo introduced in the Kconfig. It builds now.

Changes since v3:
https://lore.kernel.org/linux-kselftest/20201021061713.1...@google.com/
- Update the Kconfig entry to use "depends on" rather than "select", as
discussed in [2].
- Depend on "MSDOS_FS || VFAT_FS", rather than "FAT_FS", as we need the
CONFIG_FAT_DEFAULT_CODEPAGE symbol to be defined.

Changes since v2:
https://lore.kernel.org/linux-kselftest/20201020055856.1...@google.com/
- Comment that the export for fat_time_fat2unix() function is for KUnit
tests.

Changes since v1:
https://lore.kernel.org/linux-kselftest/20201017064107.3...@google.com/
- Now export fat_time_fat2unix() so that the test can access it when
built as a module.


[2]:
https://lore.kernel.org/linux-ext4/52959e99-4105-3de9...@infradead.org/T/#t



fs/fat/.kunitconfig | 5 ++
fs/fat/Kconfig | 14 +++-
fs/fat/Makefile | 2 +
fs/fat/fat_test.c | 197 ++++++++++++++++++++++++++++++++++++++++++++
fs/fat/misc.c | 2 +
5 files changed, 219 insertions(+), 1 deletion(-)
create mode 100644 fs/fat/.kunitconfig
create mode 100644 fs/fat/fat_test.c

diff --git a/fs/fat/.kunitconfig b/fs/fat/.kunitconfig
new file mode 100644
index 000000000000..0a6971dbeccb
--- /dev/null
+++ b/fs/fat/.kunitconfig
@@ -0,0 +1,5 @@
+CONFIG_KUNIT=y
+CONFIG_FAT_FS=y
+CONFIG_MSDOS_FS=y
+CONFIG_VFAT_FS=y
+CONFIG_FAT_KUNIT_TEST=y
diff --git a/fs/fat/Kconfig b/fs/fat/Kconfig
index 66532a71e8fd..238cc55f84c4 100644
--- a/fs/fat/Kconfig
+++ b/fs/fat/Kconfig
@@ -77,7 +77,7 @@ config VFAT_FS

config FAT_DEFAULT_CODEPAGE
int "Default codepage for FAT"
- depends on MSDOS_FS || VFAT_FS
+ depends on FAT_FS
default 437
help
This option should be set to the codepage of your FAT filesystems.
@@ -115,3 +115,15 @@ 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
+ depends on KUNIT && FAT_FS
+ 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
diff --git a/fs/fat/Makefile b/fs/fat/Makefile
index 70645ce2f7fc..2b034112690d 100644
--- a/fs/fat/Makefile
+++ b/fs/fat/Makefile
@@ -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
diff --git a/fs/fat/fat_test.c b/fs/fat/fat_test.c
new file mode 100644
index 000000000000..febd25f57d4b
--- /dev/null
+++ b/fs/fat/fat_test.c
@@ -0,0 +1,197 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit tests for FAT filesystems.
+ *
+ * Copyright (C) 2020 Google LLC.
+ * Author: David Gow <davi...@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 "), (u8)44);
+ /* With 3-letter extension. */
+ KUNIT_EXPECT_EQ(test, fat_checksum("README TXT"), (u8)115);
+ /* With short (1-letter) extension. */
+ KUNIT_EXPECT_EQ(test, fat_checksum("ABCDEFGHA "), (u8)98);
+}
+
+
+struct fat_timestamp_testcase {
+ const char *name;
+ struct timespec64 ts;
+ __le16 time;
+ __le16 date;
+ u8 cs;
+ int time_offset;
+};
+
+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 = cpu_to_le16(0),
+ .date = cpu_to_le16(33),
+ .cs = 0,
+ .time_offset = 0,
+ },
+ {
+ .name = "Latest possible UTC (2107-12-31 23:59:58)",
+ .ts = {.tv_sec = 4354819198LL, .tv_nsec = 0L},
+ .time = cpu_to_le16(49021),
+ .date = cpu_to_le16(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 = cpu_to_le16(0),
+ .date = cpu_to_le16(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 = cpu_to_le16(49021),
+ .date = cpu_to_le16(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 = cpu_to_le16(0),
+ .date = cpu_to_le16(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 = cpu_to_le16(0),
+ .date = cpu_to_le16(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 = cpu_to_le16(0),
+ .date = cpu_to_le16(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 = cpu_to_le16(48064),
+ .date = cpu_to_le16(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 = cpu_to_le16(960),
+ .date = cpu_to_le16(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 = cpu_to_le16(49021),
+ .date = cpu_to_le16(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 = cpu_to_le16(0),
+ .date = cpu_to_le16(33),
+ .cs = 1,
+ .time_offset = 0,
+ },
+};
+
+static void time_testcase_desc(struct fat_timestamp_testcase *t,
+ char *desc)
+{
+ strscpy(desc, t->name, KUNIT_PARAM_DESC_SIZE);
+}
+
+KUNIT_ARRAY_PARAM(fat_time, time_test_cases, time_testcase_desc);
+
+static void fat_time_fat2unix_test(struct kunit *test)
+{
+ static struct msdos_sb_info fake_sb;
+ struct timespec64 ts;
+ struct fat_timestamp_testcase *testcase =
+ (struct fat_timestamp_testcase *)test->param_value;
+
+ fake_sb.options.tz_set = 1;
+ fake_sb.options.time_offset = testcase->time_offset;
+
+ fat_time_fat2unix(&fake_sb, &ts,
+ testcase->time,
+ testcase->date,
+ testcase->cs);
+ KUNIT_EXPECT_EQ_MSG(test,
+ testcase->ts.tv_sec,
+ ts.tv_sec,
+ "Timestamp mismatch (seconds)\n");
+ KUNIT_EXPECT_EQ_MSG(test,
+ testcase->ts.tv_nsec,
+ ts.tv_nsec,
+ "Timestamp mismatch (nanoseconds)\n");
+}
+
+static void fat_time_unix2fat_test(struct kunit *test)
+{
+ static struct msdos_sb_info fake_sb;
+ __le16 date, time;
+ u8 cs;
+ struct fat_timestamp_testcase *testcase =
+ (struct fat_timestamp_testcase *)test->param_value;
+
+ fake_sb.options.tz_set = 1;
+ fake_sb.options.time_offset = testcase->time_offset;
+
+ fat_time_unix2fat(&fake_sb, &(testcase->ts),
+ &time, &date, &cs);
+ KUNIT_EXPECT_EQ_MSG(test,
+ le16_to_cpu(testcase->time),
+ le16_to_cpu(time),
+ "Time mismatch\n");
+ KUNIT_EXPECT_EQ_MSG(test,
+ le16_to_cpu(testcase->date),
+ le16_to_cpu(date),
+ "Date mismatch\n");
+ KUNIT_EXPECT_EQ_MSG(test,
+ testcase->cs,
+ cs,
+ "Centisecond mismatch\n");
+}
+
+static struct kunit_case fat_test_cases[] = {
+ KUNIT_CASE(fat_checksum_test),
+ KUNIT_CASE_PARAM(fat_time_fat2unix_test, fat_time_gen_params),
+ KUNIT_CASE_PARAM(fat_time_unix2fat_test, fat_time_gen_params),
+ {},
+};
+
+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");
diff --git a/fs/fat/misc.c b/fs/fat/misc.c
index 18a50a46b57f..9073fa927be3 100644
--- a/fs/fat/misc.c
+++ b/fs/fat/misc.c
@@ -229,6 +229,8 @@ void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts,
ts->tv_nsec = 0;
}
}
+/* Export fat_time_fat2unix() for the fat_test KUnit tests. */
+EXPORT_SYMBOL_GPL(fat_time_fat2unix);

/* Convert linear UNIX date to a FAT time/date pair. */
void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
--
2.31.1.368.gbe11c130af-goog

[Brendan Higgins]

On Thu, Apr 15, 2021 at 11:56:23PM -0700, David Gow wrote:
> 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

^^^^^^^^
I am guessing this is supposed to be "inspired".

> timestamp parsing KUnit tests in ext4[1].
>
> Note that, unlike fat_time_unix2fat, fat_time_fat2unix wasn't previously
> exported, so this patch exports it as well. This is required for the
> case where we're building the fat and fat_test as modules.
>
> [1]:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/ext4/inode-test.c
>
> Signed-off-by: David Gow <davi...@google.com>
> Acked-by: OGAWA Hirofumi <hiro...@mail.parknet.co.jp>

Aside from the nit above, and the *potential* nit and question below.
Everything here looks good to me.

Reviewed-by: Brendan Higgins <brendan...@google.com>

> ---
>
> It's been a while, but this hopefully is a final version of the FAT KUnit
> patchset. It has a number of changes to keep it up-to-date with current
> KUnit standards, notably the use of parameterised tests and the addition
> of a '.kunitconfig' file to allow for easy testing. It also fixes an
> endianness tagging issue picked up by the kernel test robot under sparse
> on pa-risc.
>
> Cheers,
> -- David

[...]

> diff --git a/fs/fat/fat_test.c b/fs/fat/fat_test.c
> new file mode 100644
> index 000000000000..febd25f57d4b
> --- /dev/null
> +++ b/fs/fat/fat_test.c
> @@ -0,0 +1,197 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * KUnit tests for FAT filesystems.
> + *
> + * Copyright (C) 2020 Google LLC.

Nit: I know you wrote this last year, but I have had other maintainers
tell me the Copyright date should be set to when the final version of
the patch is sent out.

I personally don't care, and I don't think you should resend this patch
just for that, but figured I would mention.

> + * Author: David Gow <davi...@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 "), (u8)44);
> + /* With 3-letter extension. */
> + KUNIT_EXPECT_EQ(test, fat_checksum("README TXT"), (u8)115);
> + /* With short (1-letter) extension. */
> + KUNIT_EXPECT_EQ(test, fat_checksum("ABCDEFGHA "), (u8)98);

How do you get the magic values? Or is this just supposed to be a
regression test?

Not going to pretend I understand FAT, but everything else in this test
makes sense from a logical/testing/readability point of view.

Cheers!

[...]

[David Gow]

On Wed, May 5, 2021 at 2:36 AM 'Brendan Higgins' via KUnit Development
<kuni...@googlegroups.com> wrote:
>
> On Thu, Apr 15, 2021 at 11:56:23PM -0700, David Gow wrote:
> > 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
> ^^^^^^^^
> I am guessing this is supposed to be "inspired".
>

Oops -- yup. This is a typo. I can resend a version with this fixed if
you think that makes sense, otherwise I'll just hold it over in case I
need to send out a new version.

Hmm... I've definitely heard this both ways, but I can easily update
the year if I need to send a new version out.

> > + * Author: David Gow <davi...@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 "), (u8)44);
> > + /* With 3-letter extension. */
> > + KUNIT_EXPECT_EQ(test, fat_checksum("README TXT"), (u8)115);
> > + /* With short (1-letter) extension. */
> > + KUNIT_EXPECT_EQ(test, fat_checksum("ABCDEFGHA "), (u8)98);
>
> How do you get the magic values? Or is this just supposed to be a
> regression test?

This is mainly meant to be a regression test, and the values did
originally come from just running fat_checksum. I have, however,
checked that Windows 98 produces the same values (on a FAT12
filesystem).

> Not going to pretend I understand FAT, but everything else in this test
> makes sense from a logical/testing/readability point of view.
>
> Cheers!
>
> [...]
>

> --
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[Brendan Higgins]

All the above sounds good to me. Like I said before, all my comments
are pretty minor, I don't think you need to send a new revision for
those.

[Daniel Latypov]

On Thu, Apr 15, 2021 at 11:56 PM 'David Gow' via KUnit Development
<kuni...@googlegroups.com> wrote:
>
> 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].
>
> Note that, unlike fat_time_unix2fat, fat_time_fat2unix wasn't previously
> exported, so this patch exports it as well. This is required for the
> case where we're building the fat and fat_test as modules.
>
> [1]:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/ext4/inode-test.c
>
> Signed-off-by: David Gow <davi...@google.com>
> Acked-by: OGAWA Hirofumi <hiro...@mail.parknet.co.jp>

Tested-by: Daniel Latypov <dlat...@google.com>

The KUnit side of things looks good to me, added some minor nits below.
I had been hoping to run this using coverage, but something about that
is newly broken for my machine, so I haven't been able to :|

Because I felt committed to checking the coverage somehow, I added
some pr_info()s to see which branches are being taken.
We're hitting all of them except for the two in fat_time_unix2fat:
* the one for dates before 1980
* the one for dates after 2107

We have the earliest and latest possible dates as test cases already,
so it's probably not that important to hit those.

> ---
>
> It's been a while, but this hopefully is a final version of the FAT KUnit
> patchset. It has a number of changes to keep it up-to-date with current
> KUnit standards, notably the use of parameterised tests and the addition
> of a '.kunitconfig' file to allow for easy testing. It also fixes an
> endianness tagging issue picked up by the kernel test robot under sparse
> on pa-risc.
>
> Cheers,
> -- David
>
> Changes since v7:
> https://lore.kernel.org/linux-kselftest/20201028064631.3...@google.com/
> - Make the two timestamp tests parameterised: this means that the KUnit
> runtime and tooling are aware of the different testcases (and print a
> nice list of them to the TAP log when the test is run).
> - Fix some issues sparse picked up with __le32 tagged integers.
> - Add an fs/fat/.kunitconfig file which contains all the Kconfig entries
> needed to run the test. The test can now be run with:
> ./tools/testing/kunit/kunit.py run --kunitconfig fs/fat/.kunitconfig

FYI, if you do rebase send out a new revision, the test can be run via
$ ./tools/testing/kunit/kunit.py run --kunitconfig fs/fat

Optional: it could be easier to read if we grouped the fields together, e.g.

struc timespec64 ts;
/* fields used by FAT */
time, date, cs;
int time_offset;

Or we could add a test-only struct

struct fat_timestamp {
time, date, cs;
};

to keep things more readable, e.g. in unix2fat_test

struct fat_timestamp got;
...
KUNIT_EXPECT_EQ_MSG(test, test_case->cs, got.cs, "...")


> +};
> +

Nit: if I delete these \n's, I don't see a difference in kunit.py output.
I also don't think I see a difference in the raw output either.

If I put \n\n, then I'll see a difference.

So should we drop these single trailing \n?

> --
> You received this message because you are subscribed to the Google Groups "KUnit Development" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to kunit-dev+...@googlegroups.com.

> To view this discussion on the web visit https://groups.google.com/d/msgid/kunit-dev/20210416065623.882364-1-davidgow%40google.com.