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