From: Miklos Szeredi <miklos@szeredi.hu>
To: libc-alpha@sourceware.org, linux-man <linux-man@vger.kernel.org>,
Alejandro Colomar <alx@kernel.org>,
Linux API <linux-api@vger.kernel.org>,
Florian Weimer <fweimer@redhat.com>,
linux-fsdevel@vger.kernel.org, Karel Zak <kzak@redhat.com>,
Ian Kent <raven@themaw.net>, David Howells <dhowells@redhat.com>,
Christian Brauner <christian@brauner.io>,
Amir Goldstein <amir73il@gmail.com>,
Arnd Bergmann <arnd@arndb.de>
Subject: [RFC] proposed libc interface and man page for listmount
Date: Tue, 5 Dec 2023 17:27:58 +0100 [thread overview]
Message-ID: <CAJfpeguMViqawKfJtM7_M9=m+6WsTcPfa_18t_rM9iuMG096RA@mail.gmail.com> (raw)
[-- Attachment #1: Type: text/plain, Size: 2071 bytes --]
Attaching the proposed man page for listing mounts (based on the new
listmount() syscall).
The raw interface is:
syscall(__NR_listmount, const struct mnt_id_req __user *, req,
u64 __user *, buf, size_t, bufsize, unsigned int, flags);
The proposed libc API is.
struct listmount *listmount_start(uint64_t mnt_id, unsigned int flags);
uint64_t listmount_next(struct listmount *lm);
void listmount_end(struct listmount *lm);
I'm on the opinion that no wrapper is needed for the raw syscall, just
like there isn't one for getdents(2).
Comments?
Thanks,
Miklos
Sample implementation:
--------------------------------
#define LM_BUFSIZE 4096
struct listmount {
size_t num;
size_t pos;
uint64_t mnt_id;
unsigned int flags;
uint64_t buf[LM_BUFSIZE];
};
static int do_listmount(struct listmount *lm)
{
struct mnt_id_req req = {
.mnt_id = lm->mnt_id,
.param = lm->buf[LM_BUFSIZE - 1],
};
long res;
res = syscall(__NR_listmount, &req, lm->buf, LM_BUFSIZE, lm->flags);
if (res != -1) {
lm->num = res;
lm->pos = 0;
}
return res;
}
struct listmount *listmount_start(uint64_t mnt_id, unsigned int flags)
{
int res;
struct listmount *lm = calloc(1, sizeof(*lm));
if (lm) {
lm->mnt_id = mnt_id;
lm->flags = flags;
res = do_listmount(lm);
if (res == -1) {
free(lm);
lm = NULL;
}
}
return lm;
}
uint64_t listmount_next(struct listmount *lm)
{
int res;
if (lm->pos == LM_BUFSIZE) {
res = do_listmount(lm);
if (res == -1)
return 0;
}
/* End of list? */
if (lm->pos == lm->num)
return 0;
return lm->buf[lm->pos++];
}
void listmount_end(struct listmount *lm)
{
free(lm);
}
[-- Attachment #2: listmount_start.3 --]
[-- Type: application/x-troff-man, Size: 1998 bytes --]
next reply other threads:[~2023-12-05 16:28 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-05 16:27 Miklos Szeredi [this message]
2023-12-05 17:51 ` [RFC] proposed libc interface and man page for listmount Matthew House
2023-12-06 9:38 ` Miklos Szeredi
2023-12-06 16:53 ` Matthew House
2023-12-05 18:26 ` Karel Zak
2023-12-06 9:40 ` Miklos Szeredi
2023-12-06 11:05 ` Florian Weimer
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