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



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 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


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