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libudev-monitor: re-implement udev_monitor_receive_sd_device()
This commit is contained in:
Yu Watanabe
parent
759d9f3f8d
commit
23c457a7fb
@ -14,6 +14,8 @@
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#include "libudev.h"
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#include "alloc-util.h"
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#include "device-private.h"
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#include "device-util.h"
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#include "fd-util.h"
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#include "fileio.h"
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#include "format-util.h"
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@ -492,6 +494,137 @@ tag:
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return 0;
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}
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static int udev_monitor_receive_device_one(struct udev_monitor *udev_monitor, sd_device **ret) {
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_cleanup_(sd_device_unrefp) sd_device *device = NULL;
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union {
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struct udev_monitor_netlink_header nlh;
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char raw[8192];
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} buf;
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struct iovec iov = {
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.iov_base = &buf,
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.iov_len = sizeof(buf)
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};
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char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
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union sockaddr_union snl;
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struct msghdr smsg = {
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.msg_iov = &iov,
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.msg_iovlen = 1,
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.msg_control = cred_msg,
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.msg_controllen = sizeof(cred_msg),
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.msg_name = &snl,
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.msg_namelen = sizeof(snl),
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};
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struct cmsghdr *cmsg;
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struct ucred *cred;
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ssize_t buflen, bufpos;
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bool is_initialized = false;
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int r;
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assert(ret);
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buflen = recvmsg(udev_monitor->sock, &smsg, 0);
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if (buflen < 0) {
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if (errno != EINTR)
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log_debug_errno(errno, "Failed to receive message: %m");
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return -errno;
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}
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if (buflen < 32 || (smsg.msg_flags & MSG_TRUNC))
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return log_debug_errno(EINVAL, "Invalid message length.");
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if (snl.nl.nl_groups == UDEV_MONITOR_NONE) {
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/* unicast message, check if we trust the sender */
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if (udev_monitor->snl_trusted_sender.nl.nl_pid == 0 ||
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snl.nl.nl_pid != udev_monitor->snl_trusted_sender.nl.nl_pid)
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return log_debug_errno(EAGAIN, "Unicast netlink message ignored.");
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} else if (snl.nl.nl_groups == UDEV_MONITOR_KERNEL) {
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if (snl.nl.nl_pid > 0)
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return log_debug_errno(EAGAIN, "Multicast kernel netlink message from PID %"PRIu32" ignored.", snl.nl.nl_pid);
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}
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cmsg = CMSG_FIRSTHDR(&smsg);
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if (!cmsg || cmsg->cmsg_type != SCM_CREDENTIALS)
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return log_debug_errno(EAGAIN, "No sender credentials received, message ignored.");
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cred = (struct ucred*) CMSG_DATA(cmsg);
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if (cred->uid != 0)
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return log_debug_errno(EAGAIN, "Sender uid="UID_FMT", message ignored.", cred->uid);
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if (streq(buf.raw, "libudev")) {
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/* udev message needs proper version magic */
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if (buf.nlh.magic != htobe32(UDEV_MONITOR_MAGIC))
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return log_debug_errno(EAGAIN, "Invalid message signature (%x != %x)",
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buf.nlh.magic, htobe32(UDEV_MONITOR_MAGIC));
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if (buf.nlh.properties_off+32 > (size_t) buflen)
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return log_debug_errno(EAGAIN, "Invalid message length (%u > %zd)",
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buf.nlh.properties_off+32, buflen);
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bufpos = buf.nlh.properties_off;
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/* devices received from udev are always initialized */
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is_initialized = true;
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} else {
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/* kernel message with header */
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bufpos = strlen(buf.raw) + 1;
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if ((size_t) bufpos < sizeof("a@/d") || bufpos >= buflen)
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return log_debug_errno(EAGAIN, "Invalid message length");
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/* check message header */
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if (!strstr(buf.raw, "@/"))
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return log_debug_errno(EAGAIN, "Invalid message header");
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}
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r = device_new_from_nulstr(&device, (uint8_t*) &buf.raw[bufpos], buflen - bufpos);
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if (r < 0)
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return log_debug_errno(r, "Failed to create device: %m");
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if (is_initialized)
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device_set_is_initialized(device);
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/* skip device, if it does not pass the current filter */
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if (passes_filter(udev_monitor, device) <= 0)
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return 0;
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*ret = TAKE_PTR(device);
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return 1;
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}
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int udev_monitor_receive_sd_device(struct udev_monitor *udev_monitor, sd_device **ret) {
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struct pollfd pfd = {
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.fd = udev_monitor->sock,
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.events = POLLIN,
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};
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int r;
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assert(udev_monitor);
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assert(ret);
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for (;;) {
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/* r == 0 means a device is received but it does not pass the current filter. */
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r = udev_monitor_receive_device_one(udev_monitor, ret);
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if (r != 0)
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return r;
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for (;;) {
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/* wait next message */
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r = poll(&pfd, 1, 0);
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if (r < 0) {
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if (IN_SET(errno, EINTR, EAGAIN))
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continue;
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return -errno;
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} else if (r == 0)
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return -EAGAIN;
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/* receive next message */
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break;
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}
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}
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}
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/**
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* udev_monitor_receive_device:
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* @udev_monitor: udev monitor
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@ -511,159 +644,19 @@ tag:
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*
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* Returns: a new udev device, or #NULL, in case of an error
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**/
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_public_ struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor)
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{
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struct udev_device *udev_device;
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struct msghdr smsg;
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struct iovec iov;
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char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
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struct cmsghdr *cmsg;
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union sockaddr_union snl;
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struct ucred *cred;
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union {
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struct udev_monitor_netlink_header nlh;
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char raw[8192];
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} buf;
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ssize_t buflen;
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ssize_t bufpos;
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bool is_initialized = false;
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_public_ struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor) {
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_cleanup_(sd_device_unrefp) sd_device *device = NULL;
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int r;
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retry:
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if (udev_monitor == NULL) {
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errno = EINVAL;
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return NULL;
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}
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iov.iov_base = &buf;
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iov.iov_len = sizeof(buf);
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memzero(&smsg, sizeof(struct msghdr));
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smsg.msg_iov = &iov;
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smsg.msg_iovlen = 1;
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smsg.msg_control = cred_msg;
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smsg.msg_controllen = sizeof(cred_msg);
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smsg.msg_name = &snl;
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smsg.msg_namelen = sizeof(snl);
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assert_return(udev_monitor, NULL);
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buflen = recvmsg(udev_monitor->sock, &smsg, 0);
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if (buflen < 0) {
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if (errno != EINTR)
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log_debug("unable to receive message");
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r = udev_monitor_receive_sd_device(udev_monitor, &device);
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if (r < 0) {
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errno = -r;
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return NULL;
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}
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if (buflen < 32 || (smsg.msg_flags & MSG_TRUNC)) {
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log_debug("invalid message length");
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errno = EINVAL;
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return NULL;
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}
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if (snl.nl.nl_groups == 0) {
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/* unicast message, check if we trust the sender */
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if (udev_monitor->snl_trusted_sender.nl.nl_pid == 0 ||
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snl.nl.nl_pid != udev_monitor->snl_trusted_sender.nl.nl_pid) {
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log_debug("unicast netlink message ignored");
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errno = EAGAIN;
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return NULL;
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}
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} else if (snl.nl.nl_groups == UDEV_MONITOR_KERNEL) {
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if (snl.nl.nl_pid > 0) {
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log_debug("multicast kernel netlink message from PID %"PRIu32" ignored",
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snl.nl.nl_pid);
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errno = EAGAIN;
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return NULL;
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}
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}
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cmsg = CMSG_FIRSTHDR(&smsg);
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if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
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log_debug("no sender credentials received, message ignored");
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errno = EAGAIN;
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return NULL;
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}
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cred = (struct ucred *)CMSG_DATA(cmsg);
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if (cred->uid != 0) {
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log_debug("sender uid="UID_FMT", message ignored", cred->uid);
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errno = EAGAIN;
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return NULL;
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}
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if (memcmp(buf.raw, "libudev", 8) == 0) {
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/* udev message needs proper version magic */
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if (buf.nlh.magic != htobe32(UDEV_MONITOR_MAGIC)) {
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log_debug("unrecognized message signature (%x != %x)",
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buf.nlh.magic, htobe32(UDEV_MONITOR_MAGIC));
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errno = EAGAIN;
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return NULL;
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}
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if (buf.nlh.properties_off+32 > (size_t)buflen) {
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log_debug("message smaller than expected (%u > %zd)",
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buf.nlh.properties_off+32, buflen);
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errno = EAGAIN;
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return NULL;
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}
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bufpos = buf.nlh.properties_off;
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/* devices received from udev are always initialized */
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is_initialized = true;
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} else {
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/* kernel message with header */
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bufpos = strlen(buf.raw) + 1;
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if ((size_t)bufpos < sizeof("a@/d") || bufpos >= buflen) {
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log_debug("invalid message length");
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errno = EAGAIN;
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return NULL;
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}
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/* check message header */
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if (strstr(buf.raw, "@/") == NULL) {
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log_debug("unrecognized message header");
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errno = EAGAIN;
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return NULL;
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}
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}
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udev_device = udev_device_new_from_nulstr(udev_monitor->udev, &buf.raw[bufpos], buflen - bufpos);
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if (!udev_device) {
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log_debug_errno(errno, "could not create device: %m");
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return NULL;
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}
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if (is_initialized)
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udev_device_set_is_initialized(udev_device);
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/* skip device, if it does not pass the current filter */
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if (!passes_filter(udev_monitor, udev_device->device)) {
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struct pollfd pfd[1];
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int rc;
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udev_device_unref(udev_device);
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/* if something is queued, get next device */
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pfd[0].fd = udev_monitor->sock;
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pfd[0].events = POLLIN;
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rc = poll(pfd, 1, 0);
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if (rc > 0)
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goto retry;
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errno = EAGAIN;
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return NULL;
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}
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return udev_device;
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}
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int udev_monitor_receive_sd_device(struct udev_monitor *udev_monitor, sd_device **ret) {
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_cleanup_(udev_device_unrefp) struct udev_device *udev_device = NULL;
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assert(ret);
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udev_device = udev_monitor_receive_device(udev_monitor);
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if (!udev_device)
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return -errno;
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*ret = sd_device_ref(udev_device->device);
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return 0;
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return udev_device_new(udev_monitor->udev, device);
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}
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int udev_monitor_send_device(struct udev_monitor *udev_monitor,
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