[RFC PATCH] samples/landlock: Fix building on musl libc

[RFC PATCH] samples/landlock: Fix building on musl libc

[Brahmajit Das]

Building with make allyesconfig on musl results in the following

In file included from samples/landlock/sandboxer.c:22:
/usr/include/sys/prctl.h:88:8: error: redefinition of 'struct prctl_mm_map'
   88 | struct prctl_mm_map {
      |        ^~~~~~~~~~~~
In file included from samples/landlock/sandboxer.c:16:
usr/include/linux/prctl.h:134:8: note: originally defined here
  134 | struct prctl_mm_map {
      |        ^~~~~~~~~~~~

This is mainly due to differnece in the sys/prctl.h between glibC and
musl. The struct prctl_mm_map is defined in sys/prctl.h in musl.

Signed-off-by: Brahmajit Das <listout@listout.xyz>
---
 samples/landlock/sandboxer.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c
index 4e2854c6f9a3..3cc990618f5b 100644
--- a/samples/landlock/sandboxer.c
+++ b/samples/landlock/sandboxer.c
@@ -13,7 +13,9 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <linux/landlock.h>
+#if defined(__GLIBC__)
 #include <linux/prctl.h>
+#endif
 #include <linux/socket.h>
 #include <stddef.h>
 #include <stdio.h>
-- 
2.50.0

Re: [RFC PATCH] samples/landlock: Fix building on musl libc

[Mickaël Salaün]

On Tue, Jul 01, 2025 at 02:02:48AM +0530, Brahmajit Das wrote:
> Building with make allyesconfig on musl results in the following
> 
> In file included from samples/landlock/sandboxer.c:22:
> /usr/include/sys/prctl.h:88:8: error: redefinition of 'struct prctl_mm_map'
>    88 | struct prctl_mm_map {
>       |        ^~~~~~~~~~~~
> In file included from samples/landlock/sandboxer.c:16:
> usr/include/linux/prctl.h:134:8: note: originally defined here
>   134 | struct prctl_mm_map {
>       |        ^~~~~~~~~~~~
> 
> This is mainly due to differnece in the sys/prctl.h between glibC and
> musl. The struct prctl_mm_map is defined in sys/prctl.h in musl.
> 
> Signed-off-by: Brahmajit Das <listout@listout.xyz>

Thanks, applied to my -next tree. I just moved down the if/include/endif
block.

I tested it with check-linux.sh from
https://github.com/landlock-lsm/landlock-test-tools
  ARCH=x86_64 CC=musl-gcc check-linux.sh build

> ---
>  samples/landlock/sandboxer.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c
> index 4e2854c6f9a3..3cc990618f5b 100644
> --- a/samples/landlock/sandboxer.c
> +++ b/samples/landlock/sandboxer.c
> @@ -13,7 +13,9 @@
>  #include <errno.h>
>  #include <fcntl.h>
>  #include <linux/landlock.h>
> +#if defined(__GLIBC__)
>  #include <linux/prctl.h>
> +#endif
>  #include <linux/socket.h>
>  #include <stddef.h>
>  #include <stdio.h>
> -- 
> 2.50.0
> 
>