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udev-dev: enumerate DRM primary nodes via hw.dri sysctl in jails #18

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udev-dev: enumerate DRM primary nodes via hw.dri sysctl in jails #18

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61 changes: 28 additions & 33 deletions udev-dev.c
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Original file line number Diff line number Diff line change
Expand Up @@ -111,23 +111,15 @@ udev_dev_enumerate_cb(const char *path, mode_t type, void *arg)

#ifdef HAVE_SYSCTLBYNAME
/*
* Enumerate evdev input devices via the kern.evdev.input sysctl subtree.
* This is a fallback for jails where /dev/input/ is not exposed via devfs
* but the kern.evdev.input.* sysctls remain readable.
*
* We use the FreeBSD sysctl tree-walk protocol (OID 0.2 = CTL_SYSCTL_NEXT)
* to discover exactly the children that exist under kern.evdev.input, with
* no fixed upper bound. CTL_SYSCTL_NEXT skips CTLTYPE_NODE containers, so
* the walk lands on leaves of depth parent_len+2 such as
* kern.evdev.input.N.name rather than on kern.evdev.input.N itself.
* Each group of consecutive leaves sharing the same parent OID component at
* index parent_len corresponds to one evdev unit. When the component at
* next[parent_len] changes, we call CTL_SYSCTL_NAME on the depth-(parent_len+1)
* prefix to resolve the unit number N as a string, then add /dev/input/eventN.
* This yields each unit exactly once with no fixed upper bound.
* Walk a sysctl subtree rooted at root_name, discovering child units by their
* trailing numeric component. For each unit N found, add syspath_fmt % N to
* the enumerate. Uses the FreeBSD OID tree-walk protocol: CTL_SYSCTL_NEXT
* (0.2) to iterate leaves, CTL_SYSCTL_NAME (0.1) to resolve the unit number.
* Returns 0 on success or if root_name is absent; -1 on allocation error.
*/
static int
udev_dev_enumerate_evdev_sysctl(struct udev_enumerate *ue)
enumerate_sysctl_units(struct udev_enumerate *ue, const char *root_name,
const char *syspath_fmt)
{
int parent_mib[CTL_MAXNAME];
size_t parent_len;
Expand All @@ -146,10 +138,9 @@ udev_dev_enumerate_evdev_sysctl(struct udev_enumerate *ue)

parent_len = CTL_MAXNAME;
last_unit_oid = -1;
if (sysctlnametomib("kern.evdev.input", parent_mib, &parent_len) < 0)
return (0); /* no evdev support; nothing to enumerate */
if (sysctlnametomib(root_name, parent_mib, &parent_len) < 0)
return (0);

/* Seed the walk: oid[0..1] = { 0, 2 } (CTL_SYSCTL_NEXT), then parent */
oid[0] = 0;
oid[1] = 2; /* CTL_SYSCTL_NEXT */
memcpy(&oid[2], parent_mib, parent_len * sizeof(int));
Expand All @@ -158,30 +149,20 @@ udev_dev_enumerate_evdev_sysctl(struct udev_enumerate *ue)
for (;;) {
nextlen = sizeof(next);
if (sysctl(oid, (u_int)oidlen, next, &nextlen, NULL, 0) < 0)
break; /* end of tree or error — done */
break;

next_count = nextlen / sizeof(int);

/* Stop when we have walked out of the kern.evdev.input subtree */
if (next_count <= parent_len ||
memcmp(next, parent_mib, parent_len * sizeof(int)) != 0)
break;

/*
* next[parent_len] is the internal OID number of the unit
* node. When it changes we have entered a new unit's subtree.
* Resolve the unit number by asking CTL_SYSCTL_NAME for the
* depth-(parent_len+1) prefix, which yields the string
* "kern.evdev.input.N"; parse N from the last token.
*/
if (next_count >= parent_len + 2 &&
next[parent_len] != last_unit_oid) {
last_unit_oid = next[parent_len];

name_oid[0] = 0;
name_oid[1] = 1; /* CTL_SYSCTL_NAME */
memcpy(&name_oid[2], next,
(parent_len + 1) * sizeof(int));
memcpy(&name_oid[2], next, (parent_len + 1) * sizeof(int));
namelen = sizeof(name) - 1;
if (sysctl(name_oid, (u_int)(parent_len + 3),
name, &namelen, NULL, 0) < 0)
Expand All @@ -195,19 +176,31 @@ udev_dev_enumerate_evdev_sysctl(struct udev_enumerate *ue)
if (*endp != '\0')
goto advance;

snprintf(syspath, sizeof(syspath),
DEV_PATH_ROOT "/input/event%d", unit);
snprintf(syspath, sizeof(syspath), syspath_fmt, unit);
if (udev_enumerate_add_device(ue, syspath) == -1)
return (-1);
}

advance:
/* Advance: ask for the next OID after `next` */
memcpy(&oid[2], next, nextlen);
oidlen = next_count + 2;
}
return (0);
}

static int
udev_dev_enumerate_evdev_sysctl(struct udev_enumerate *ue)
{
return (enumerate_sysctl_units(ue, "kern.evdev.input",
DEV_PATH_ROOT "/input/event%d"));
}

static int
udev_dev_enumerate_drm_sysctl(struct udev_enumerate *ue)
{
return (enumerate_sysctl_units(ue, "hw.dri",
DEV_PATH_ROOT "/dri/card%d"));
}
#endif /* HAVE_SYSCTLBYNAME */

int
Expand All @@ -233,6 +226,8 @@ udev_dev_enumerate(struct udev_enumerate *ue)
if (sysctlbyname("security.jail.jailed", &jailed, &jailed_len, NULL,
0) == 0 && jailed != 0) {
ret = udev_dev_enumerate_evdev_sysctl(ue);
if (ret == 0)
ret = udev_dev_enumerate_drm_sysctl(ue);
}
#endif
return (ret);
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