tint2/src/util/uevent.c

208 lines
5.4 KiB
C

/**************************************************************************
*
* Linux Kernel uevent handler
*
* Copyright (C) 2015 Sebastian Reichel <sre@ring0.de>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version 2
* or any later version as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
**************************************************************************/
#include "uevent.h"
int uevent_fd = -1;
#ifdef ENABLE_UEVENT
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <linux/types.h>
#include <linux/netlink.h>
#include "common.h"
static struct sockaddr_nl nls;
static GList *notifiers = NULL;
static const char *has_prefix(const char *str, const char *end, const char *prefix, size_t prefixlen)
{
if ((end - str) < prefixlen)
return NULL;
if (!memcmp(str, prefix, prefixlen))
return str + prefixlen;
return NULL;
}
#define HAS_CONST_PREFIX(str, end, prefix) has_prefix((str), end, prefix, sizeof(prefix) - 1)
static void uevent_param_free(gpointer data)
{
struct uevent_parameter *param = data;
free(param->key);
free(param->val);
free(param);
}
static void uevent_free(struct uevent *ev)
{
free(ev->path);
free(ev->subsystem);
g_list_free_full(ev->params, uevent_param_free);
free(ev);
}
static struct uevent *uevent_new(char *buffer, int size)
{
gboolean first = TRUE;
if (size == 0)
return NULL;
struct uevent *ev = calloc(1, sizeof(*ev));
if (!ev)
return NULL;
/* ensure nul termination required by strlen() */
buffer[size - 1] = '\0';
const char *s = buffer;
const char *end = s + size;
for (; s < end; s += strlen(s) + 1) {
if (first) {
const char *p = strchr(s, '@');
if (!p) {
/* error: kernel events contain @ */
/* triggered by udev events, though */
free(ev);
return NULL;
}
ev->path = strdup(p + 1);
first = FALSE;
} else {
const char *val;
if ((val = HAS_CONST_PREFIX(s, end, "ACTION=")) != NULL) {
if (!strcmp(val, "add"))
ev->action = UEVENT_ADD;
else if (!strcmp(val, "remove"))
ev->action = UEVENT_REMOVE;
else if (!strcmp(val, "change"))
ev->action = UEVENT_CHANGE;
else
ev->action = UEVENT_UNKNOWN;
} else if ((val = HAS_CONST_PREFIX(s, end, "SEQNUM=")) != NULL) {
ev->sequence = atoi(val);
} else if ((val = HAS_CONST_PREFIX(s, end, "SUBSYSTEM=")) != NULL) {
ev->subsystem = strdup(val);
} else {
val = strchr(s, '=');
if (val) {
struct uevent_parameter *param = malloc(sizeof(*param));
if (param) {
param->key = strndup(s, val - s);
param->val = strdup(val + 1);
ev->params = g_list_append(ev->params, param);
}
}
}
}
}
return ev;
}
void uevent_register_notifier(struct uevent_notify *nb)
{
notifiers = g_list_append(notifiers, nb);
}
void uevent_unregister_notifier(struct uevent_notify *nb)
{
GList *l = notifiers;
while (l != NULL) {
GList *next = l->next;
struct uevent_notify *lnb = l->data;
if (memcmp(nb, lnb, sizeof(struct uevent_notify)) == 0)
notifiers = g_list_delete_link(notifiers, l);
l = next;
}
}
void uevent_handler()
{
if (uevent_fd < 0)
return;
char buf[512];
int len = recv(uevent_fd, buf, sizeof(buf), MSG_DONTWAIT);
if (len < 0)
return;
struct uevent *ev = uevent_new(buf, len);
if (ev) {
for (GList *l = notifiers; l; l = l->next) {
struct uevent_notify *nb = l->data;
if (!(ev->action & nb->action))
continue;
if (nb->subsystem && strcmp(ev->subsystem, nb->subsystem))
continue;
nb->cb(ev, nb->userdata);
}
uevent_free(ev);
}
}
int uevent_init()
{
/* Open hotplug event netlink socket */
memset(&nls, 0, sizeof(struct sockaddr_nl));
nls.nl_family = AF_NETLINK;
nls.nl_pid = getpid();
nls.nl_groups = -1;
/* open socket */
uevent_fd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
if (uevent_fd < 0) {
fprintf(stderr, "Error: socket open failed\n");
return -1;
}
/* Listen to netlink socket */
if (bind(uevent_fd, (void *)&nls, sizeof(struct sockaddr_nl))) {
fprintf(stderr, "Bind failed\n");
return -1;
}
fprintf(stderr, "Kernel uevent interface initialized...\n");
return uevent_fd;
}
void uevent_cleanup()
{
if (uevent_fd >= 0)
close(uevent_fd);
}
#endif