[libvirt] [PATCH] virprocess: Extend list of platforms for setns wrapper

[Michal Privoznik]

On 15.09.2014 16:20, Pavel Hrdina wrote:
> On 09/15/2014 03:43 PM, Michal Privoznik wrote:
>> Currently, the setns() wrapper is supported only for x86_64 and i686
>> which leaves us failing to build on other platforms like arm, aarch64
>> and so on. This means, that the wrapper needs to be extended to those
>> platforms and make to fail on runtime not compile time.
>>
>> The syscall numbers for other platforms was fetched using this
>> command:
>>
>> kernel.git $ git grep "define.*__NR_setns" | grep -e arm -e powerpc -e
>> s390
>> arch/arm/include/uapi/asm/unistd.h:#define
>> __NR_setns                   (__NR_SYSCALL_BASE+375)
>> arch/arm64/include/asm/unistd32.h:#define __NR_setns 375
>> arch/powerpc/include/uapi/asm/unistd.h:#define
>> __NR_setns               350
>> arch/s390/include/uapi/asm/unistd.h:#define __NR_setns          339
>>
>> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
>> ---
>>   src/util/virprocess.c | 18 ++++++++++++------
>>   1 file changed, 12 insertions(+), 6 deletions(-)
>>
>> diff --git a/src/util/virprocess.c b/src/util/virprocess.c
>> index 3dae1bd..eac49f5 100644
>> --- a/src/util/virprocess.c
>> +++ b/src/util/virprocess.c
>> @@ -71,27 +71,33 @@ VIR_LOG_INIT("util.process");
>>   #  define __NR_setns 308
>>   # elif defined(__i386__)
>>   #  define __NR_setns 346
>> -# else
>> -#  error "__NR_setns is not defined"
>> +# elif defined(__arm__)
>> +#  define __NR_setns 375
>> +# elif defined(__aarch64__)
>> +#  define __NR_setns 375
>> +# elif defined(__powerpc__)
>> +#  define __NR_setns 350
>> +# elif defined(__s390__)
>> +#  define __NR_setns 339
>>   # endif
>>   #endif
>>
>>   #ifndef HAVE_SETNS
>> -# ifndef WIN32
>> +# ifdef __NR_setns
>
> This would work only if the macro wasn't defined in kernel, but it seems
> that it's defined also for WIN32.

Oh my, why the heck do they claim something is supported when it's 
clearly not?! This needs to be squashed in then:

diff --git a/src/util/virprocess.c b/src/util/virprocess.c
index eac49f5..806e7f9 100644
--- a/src/util/virprocess.c
+++ b/src/util/virprocess.c
@@ -83,21 +83,21 @@ VIR_LOG_INIT("util.process");
  #endif

  #ifndef HAVE_SETNS
-# ifdef __NR_setns
+# if defined(__NR_setns) && !defined(WIN32)
  #  include <sys/syscall.h>

  static inline int setns(int fd, int nstype)
  {
      return syscall(__NR_setns, fd, nstype);
  }
-# else /* __NR_setns */
+# else /* __NR_setns && !WIN32 */
  static inline int setns(int fd ATTRIBUTE_UNUSED, int nstype 
ATTRIBUTE_UNUSED)
  {
      virReportSystemError(ENOSYS, "%s",
                           _("Namespaces are not supported on this 
platform."));
      return -1;
  }
-# endif /* __NR_setns */
+# endif /* __NR_setns && !WIN32 */
  #endif /* HAVE_SETNS */

  /**



The other approach would be just to require new enough glibc. Opinions?

Michal