On Wed, Dec 6, 2023 at 4:38 AM Miklos Szeredi <miklos@xxxxxxxxxx> wrote: > On Tue, 5 Dec 2023 at 18:51, Matthew House <mattlloydhouse@xxxxxxxxx> wrote: > > One use case I've been thinking of involves inspecting the mount list > > between syscall(__NR_clone3) and _exit(), so it has to be async-signal- > > safe. It would be nice if there were a libc wrapper that accepted a user- > > provided buffer and was async-signal-safe, so that I wouldn't have to add > > yet another syscall wrapper and redefine the kernel types just for this > > use case. (I can't trust the libc not to make its own funny versions of the > > types' layouts for its own ends.) > > You can just #include <linux/mount.h> directly. The problem with including the <linux/*> headers is that they conflict with the regular libc headers. So for instance, if I try to include both <linux/mount.h> (for the listmount(2) kernel types) and <sys/mount.h> (for the mount(2) and umount2(2) wrappers) on glibc, then I'll get a conflicting definition for every single MS_* macro. I suppose I could try to put all the listmount(2) stuff in a separate file, but that would still require manual redefinitions of the listmount(2) flags, unless I trusted libc to have its own identical redefinitions in <sys/mount.h> or whatever header the wrapper would end up in, instead of shuffling stuff around and translating it. Also, my current style in C is to put all related code into a single file as possible, which this would interfere with. At that point, I might as well redefine the whole thing. Thank you, Matthew House
