There are some platforms where 'char' is unsigned, by default
(RPi, s390x to name a few). And because of how test_demo is
written we are experiencing some test cases failing there. For
instance: /xdr/struct-scalar is failing. This is because in the
test (test_struct_scalar()), we have a struct with two chars. One
is initialized to 0xca, the other 0xfe (note that both have the
MSB set). The XDR encoder (xdr_TestStructScalar()) then calls
xdr_char() on both of them. But XDR itself has no notion of
char type, so under the hood, it expands it to int [1] and calls
xdr_int(). And this is where the problem lies. On platforms where
char is signed, the integer expansion results in 0xffffffca, but
on platforms where char is unsigned it results in 0x000000ca. Two
distinct results.

The test then goes and compares the encoded buffer with an
expected one (memcmp(), read from the disk earlier).

This poses no problem for real life use, because when decoding
those chars back, the padding is thrown away.

To avoid tickling this issue, use values that don't have the MSB
set.

1: https://git.linux-nfs.org/?p=steved/libtirpc.git;a=blob;f=src/xdr.c;h=28d1382cc4853ecf1238d792af5016160435d1e0;hb=HEAD#l487

Reported-by: Boris Fiuczynski <fiuczy@linux.ibm.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
---
 scripts/rpcgen/tests/test_demo.c              |   2 +-
 .../tests/test_demo_struct_fixed_array.bin    | Bin 136 -> 136 bytes
 .../tests/test_demo_struct_pointer_set.bin    | Bin 12 -> 12 bytes
 .../rpcgen/tests/test_demo_struct_scalar.bin  | Bin 8 -> 8 bytes
 .../test_demo_struct_variable_array_set.bin   | Bin 28 -> 28 bytes
 .../tests/test_demo_test_struct_all_types.bin | Bin 1752 -> 1752 bytes
 6 files changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/rpcgen/tests/test_demo.c b/scripts/rpcgen/tests/test_demo.c
index 1cdb9cfb82..a48ceccd58 100644
--- a/scripts/rpcgen/tests/test_demo.c
+++ b/scripts/rpcgen/tests/test_demo.c
@@ -373,7 +373,7 @@ static void test_enum_variable_array_empty(void)
              &vorig, &vnew, "enum_variable_array_empty", false);
 }
 
-#define TEST_STRUCT_INIT (TestStruct) { .c1 = 0xca, .c2 = 0xfe }
+#define TEST_STRUCT_INIT (TestStruct) { .c1 = 0x4a, .c2 = 0x7e }
 #define TEST_STRUCT_INIT_ALT (TestStruct) { .c1 = 0x09, .c2 = 0x07 }
 
 static void test_struct_scalar(void)
diff --git a/scripts/rpcgen/tests/test_demo_struct_fixed_array.bin b/scripts/rpcgen/tests/test_demo_struct_fixed_array.bin
index f0e786ddea02cbd342ec9f6d3c6ee2b090b38792..dfa991acbdb4b5cfd48a43d9c3e5e118282e2c95 100644
GIT binary patch
literal 136
lcmZQzVDMsKV5kFPP9SCnVst((ahN(nG)zB?Mpq9O2LK<k2tfb<

literal 136
ncmezW|Np7~|NsAEU|`?`Vs;=Kg^x=drj8H|(+{K3)x*RAqQp)G

diff --git a/scripts/rpcgen/tests/test_demo_struct_pointer_set.bin b/scripts/rpcgen/tests/test_demo_struct_pointer_set.bin
index 572814793222ad03346747bb3041bb7eafc5205e..0aa91c2b571fb80d49f966e259220410b415f003 100644
GIT binary patch
literal 12
RcmZQzU|?imVDJLsIsgI%0LlOW

literal 12
ScmZQzU|{_J|Nki<{s#ae=Lf_9

diff --git a/scripts/rpcgen/tests/test_demo_struct_scalar.bin b/scripts/rpcgen/tests/test_demo_struct_scalar.bin
index 0e6959d56a3ced8e5a656342f7a6a4e8cfb4b779..aa46538fb8fb946dd368ff954b373e5d0399d449 100644
GIT binary patch
literal 8
PcmZQzVDMsKV5kEC0r&vP

literal 8
QcmezW|Np7~|Ns9303zB4!vFvP

diff --git a/scripts/rpcgen/tests/test_demo_struct_variable_array_set.bin b/scripts/rpcgen/tests/test_demo_struct_variable_array_set.bin
index a9406a21cf6b767b76e2041536e560f5ef3c0202..48c2e710e9355c089471129b48f99159bbdf1339 100644
GIT binary patch
literal 28
YcmZQzU|?ooVDJLsIw0l*Vs;n}01v+a>;M1&

literal 28
acmZQzU||0L|Nki<{>Q+;zzM|cFd6`$K?mjl

diff --git a/scripts/rpcgen/tests/test_demo_test_struct_all_types.bin b/scripts/rpcgen/tests/test_demo_test_struct_all_types.bin
index 5ee4ee5a6d5e467e373add81d6266f4acee2a150..660c0e1b9c43046b790bda9c25a297653b714db0 100644
GIT binary patch
literal 1752
zcmds%ziI+O5QpbH{0G6x!q>2}Q`1S_BVZw<jA^vC&8wsrt`mKrphY$_iJ!=jVId%>
z2g^6Vncp1ixVIuQ7m>G=(q7q7j6@oh>U7vVuAtV6VgKP{T=hOD%iX(a^Zin4%2L;*
z9(#9FS4&r0SAF_Co4sgI)Jof85izMppR(9~8FkM;d%b4bZ?$={$0v;!M@<ZE7B&~J
zqddMG>4%Zu*U^wZugOQm4|6{1_@U3Eq0O4u_jJ$BH}R2;sy<l1YOm8#9$$|1!^rRJ
yXh@&e<RjvTIUjZW(C5)Pp8D;731-Wk15bBP_Kx`DF5nyc4{zx^z1MRdo|A9XGs+YI

literal 1752
zcmds%ze+<<42N@iX{#Vk9efR^ZvNSPk%B|PQJtJ!`zqaqyGeZ@(ZSPSs$Y@Na0U^y
z7s7Xv{Bp?+=f=$L%<R6_`X(L==Vqf`etmzwe1yuCv(uyHMSt>o_3*NA-*um~f!N7@
z>+yGwWe2iD+3<QcpWo<E2A#K9GFEBybY=D7RL`4U|1$kseV&^h^=&JeH(xkI#e5dy
z=x1?sEm99Neaz!S>Y`6PBYN1<kw*_>93M*OmxuYrSx&y)Z_ZyF^~34Yt?GlH#nH7$
zJ<Rkmj}NJfKJkp`VM|9IJ&bYu7Ps~O4<xf?=fLgmY3_&}yWl5#;6MGR`+CpQd$I;<
CFZ~+;

-- 
2.41.0
_______________________________________________
Devel mailing list -- devel@lists.libvirt.org
To unsubscribe send an email to devel-leave@lists.libvirt.org

Michal,
thanks for fixing this.
I might want to add into the commit message that this was introduced 
with commit:
40cbaa8fbe rpcgen: add test case for XDR serialization

Reviewed-by: Boris Fiuczynski <fiuczy@linux.ibm.com>

and tested as well.

On 11/29/23 13:00, Michal Privoznik wrote:
> There are some platforms where 'char' is unsigned, by default
> (RPi, s390x to name a few). And because of how test_demo is
> written we are experiencing some test cases failing there. For
> instance: /xdr/struct-scalar is failing. This is because in the
> test (test_struct_scalar()), we have a struct with two chars. One
> is initialized to 0xca, the other 0xfe (note that both have the
> MSB set). The XDR encoder (xdr_TestStructScalar()) then calls
> xdr_char() on both of them. But XDR itself has no notion of
> char type, so under the hood, it expands it to int [1] and calls
> xdr_int(). And this is where the problem lies. On platforms where
> char is signed, the integer expansion results in 0xffffffca, but
> on platforms where char is unsigned it results in 0x000000ca. Two
> distinct results.
> 
> The test then goes and compares the encoded buffer with an
> expected one (memcmp(), read from the disk earlier).
> 
> This poses no problem for real life use, because when decoding
> those chars back, the padding is thrown away.
> 
> To avoid tickling this issue, use values that don't have the MSB
> set.
> 
> 1:https://git.linux-nfs.org/?p=steved/libtirpc.git;a=blob;f=src/xdr.c;h=28d1382cc4853ecf1238d792af5016160435d1e0;hb=HEAD#l487
> 
> Reported-by: Boris Fiuczynski<fiuczy@linux.ibm.com>
> Signed-off-by: Michal Privoznik<mprivozn@redhat.com>
> ---
>   scripts/rpcgen/tests/test_demo.c              |   2 +-
>   .../tests/test_demo_struct_fixed_array.bin    | Bin 136 -> 136 bytes
>   .../tests/test_demo_struct_pointer_set.bin    | Bin 12 -> 12 bytes
>   .../rpcgen/tests/test_demo_struct_scalar.bin  | Bin 8 -> 8 bytes
>   .../test_demo_struct_variable_array_set.bin   | Bin 28 -> 28 bytes
>   .../tests/test_demo_test_struct_all_types.bin | Bin 1752 -> 1752 bytes
>   6 files changed, 1 insertion(+), 1 deletion(-)

-- 
Mit freundlichen Grüßen/Kind regards
    Boris Fiuczynski

IBM Deutschland Research & Development GmbH
Vorsitzender des Aufsichtsrats: Gregor Pillen
Geschäftsführung: David Faller
Sitz der Gesellschaft: Böblingen
Registergericht: Amtsgericht Stuttgart, HRB 243294
_______________________________________________
Devel mailing list -- devel@lists.libvirt.org
To unsubscribe send an email to devel-leave@lists.libvirt.org