On Wed, Jul 24, 2013 at 11:31 AM, Ian Kent <raven@xxxxxxxxxx> wrote:
> On Wed, 2013-07-24 at 10:37 +0800, Lan Yixun (dlan) wrote:
>> From: "Lan Yixun (dlan)" <dennis.yxun@xxxxxxxxx>
>>
>> this is need when libtirpc is enabled, otherwise autofs fail to start
>> due to it can't find symbol clnt_dg_create (which is provided by libtirpc)
>
> Yeah, I use libtirpc all the time but that's something I haven't
> noticed, probably because TIRPC_WORKAROUND will cause the library to be
> dlopen()ed at start.
>
> So while the change is needed and I'll apply it, I'm not sure why you're
> seeing it since the library should be open and loaded already.
>
>>
>> ---
>> autofs error log from /var/log/message:
>>
>> Jul 23 12:11:58 ofire automount[25699]: open_mount:244: parse(sun): cannot open mount module
>> nfs (/usr/lib64/autofs/mount_nfs.so: undefined symbol: clnt_dg_create)
>> Jul 23 12:11:58 ofire automount[25699]: lookup(file): failed to open parse context
>>
>> without this patch, mount_nfs.so fail link to libtirpc.so
>> # ldd /usr/lib64/autofs/mount_nfs.so |grep tirpc
>>
>> with this patch applied:
>> # ldd /usr/lib64/autofs/mount_nfs.so |grep tirpc
>> libtirpc.so.1 => /lib64/libtirpc.so.1 (0x00007f7d94920000)
>>
>> Signed-off-by: Lan Yixun (dlan) <dennis.yxun@xxxxxxxxx>
>> ---
>> modules/Makefile | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/modules/Makefile b/modules/Makefile
>> index 4bb1096..0fe8ae8 100644
>> --- a/modules/Makefile
>> +++ b/modules/Makefile
>> @@ -116,6 +116,6 @@ lookup_ldap.so: lookup_ldap.c dclist.o base64.o $(SASL_OBJ)
>>
>> mount_nfs.so: mount_nfs.c replicated.o
>> $(CC) $(SOLDFLAGS) $(CFLAGS) -o mount_nfs.so \
>> - mount_nfs.c replicated.o $(AUTOFS_LIB) $(LIBNSL)
>> + mount_nfs.c replicated.o $(AUTOFS_LIB) $(LIBNSL) $(TIRPCLIB)
>> $(STRIP) mount_nfs.so
>>
>
>
Hi Ian:
I spend a few time dig into the code, and found the root cause.
In gentoo linux, user are legal to pass customized CFLAGS/LDFLAGS,
and here we append "-Wl,--as-needed" to LDFLAGS.
with this flag append, the final image - "automount" won't link to
library tirpc.
command of "ldd /usr/sbin/automount |grep tirpc" shows nothing. I
think this is totally fine, since autmount itself doesn't use any
symbol from libtirpc.
but without my previous patch, the mount_nfs.so don't link to
libtirpc, see following.
# ldd /usr/lib64/autofs/mount_nfs.so
linux-vdso.so.1 (0x00007fff4bfff000)
libnsl.so.1 => /lib64/libnsl.so.1 (0x00007fc55957c000)
libc.so.6 => /lib64/libc.so.6 (0x00007fc5591d1000)
/lib64/ld-linux-x86-64.so.2 (0x00007fc559a04000)
#objdump -t /usr/lib64/autofs/mount_nfs.so |grep clnt_dg_creat
0000000000000000 *UND* 0000000000000000
clnt_dg_create
you can see clnt_dg_create is a undefined symbol, which is come from libtirpc.
so, module mount_nfs need libtirpc.
I think you haven't encounter the problem is that the application
automont accidentally link in libtirpc, while mount_nfs.so doesn't. so
mount_nfs.so can found the symbol which loaded by automount when it
started to run.
I can filter the "-Wl,--as-needed" flag, but still think my patch
address right to the problem.
Thanks.
Dennis Lan (dlan)
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