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evdev: get devnum through sysctl when available #15

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17 changes: 17 additions & 0 deletions udev-dev.c
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@
#include <assert.h>
#include <fcntl.h>
#include <fnmatch.h>
#include <inttypes.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
Expand Down Expand Up @@ -267,6 +268,7 @@ create_evdev_handler(struct udev_device *ud)
unsigned long sw_bits[NLONGS(SW_CNT)];
unsigned long prp_bits[NLONGS(INPUT_PROP_CNT)];
struct input_id id;
uint64_t devnum = 0;
#ifdef HAVE_SYSCTLBYNAME
const char *unit;
char mib[32];
Expand Down Expand Up @@ -316,6 +318,16 @@ create_evdev_handler(struct udev_device *ud)
if (sysctlbyname(mib, prp_bits, &len, NULL, 0) < 0)
goto use_ioctl;

/*
* devnum sysctl is optional: sysctlbyname on kernels predacting its
* introduction will fail but that does not mean we should fall back to
* ioctl. We just leave devnum untouched, with its initialization value
* of zero.
*/
snprintf(mib, sizeof(mib), "kern.evdev.input.%s.devnum", unit);
len = sizeof(devnum);
(void)sysctlbyname(mib, &devnum, &len, NULL, 0);

goto found_values;

use_ioctl:
Expand Down Expand Up @@ -346,6 +358,11 @@ create_evdev_handler(struct udev_device *ud)
#ifdef HAVE_SYSCTLBYNAME
found_values:
#endif
if (devnum != 0) {
udev_list_insertf(udev_device_get_properties_list(ud),
"DEVNUM", "%" PRIu64, devnum);
}

/* Derived from EvdevProbe() function of xf86-input-evdev driver */
has_keys = bit_find(key_bits, 0, BTN_MISC);
has_buttons = bit_find(key_bits, BTN_MISC, BTN_JOYSTICK);
Expand Down
12 changes: 12 additions & 0 deletions udev-device.c
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Original file line number Diff line number Diff line change
Expand Up @@ -439,8 +439,20 @@ udev_device_get_devnum(struct udev_device *ud)
{
const char *devpath;
struct stat st;
const char *dn;

TRC("(%p) %s", ud, ud->syspath);

/*
* If a DEVNUM udev property is set (populated from a kernel
* sysctl by the evdev create handler), trust it. This avoids a
* stat(2) that would fail when the device node is not visible, such as
* in a jail without devfs.
*/
dn = udev_device_get_property_value(ud, "DEVNUM");
if (dn != NULL)
return ((dev_t)strtoull(dn, NULL, 10));

devpath = get_devpath_by_syspath(ud->syspath);
if (devpath == NULL ||
stat(devpath, &st) < 0 ||
Expand Down