From e2c236b300e4fa9f4f7fdb672251892c2be3e149 Mon Sep 17 00:00:00 2001
From: Christoph Lohmann <20h@r-36.net>
Date: Sun, 15 Apr 2012 23:08:48 +0200
Subject: Initial commit.

---
 nldev.c | 288 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 288 insertions(+)
 create mode 100644 nldev.c

(limited to 'nldev.c')

diff --git a/nldev.c b/nldev.c
new file mode 100644
index 0000000..400379a
--- /dev/null
+++ b/nldev.c
@@ -0,0 +1,288 @@
+/*
+ * Copy me if you can.
+ * by 20h
+ */
+
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <poll.h>
+#include <ctype.h>
+#include <string.h>
+#include <errno.h>
+#include <signal.h>
+#include <libgen.h>
+#include <fcntl.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/stat.h>
+#include <linux/types.h>
+#include <linux/netlink.h>
+
+#include "arg.h"
+
+char *argv0;
+int listfd = -1;
+int dofork = 0, dodebug = 0;
+
+void
+edie(char *fmt, ...)
+{
+	va_list fmtargs;
+
+	va_start(fmtargs, fmt);
+	vfprintf(stderr, fmt, fmtargs);
+	va_end(fmtargs);
+	fprintf(stderr, ": ");
+
+	perror(NULL);
+
+	exit(1);
+}
+
+void
+die(char *fmt, ...)
+{
+	va_list fmtargs;
+
+	va_start(fmtargs, fmt);
+	vfprintf(stderr, fmt, fmtargs);
+	va_end(fmtargs);
+
+	exit(1);
+}
+
+void
+dbg(char *fmt, ...)
+{
+	va_list fmtargs;
+
+	if (dodebug) {
+		fprintf(stderr, "%s: ", argv0);
+		va_start(fmtargs, fmt);
+		vfprintf(stderr, fmt, fmtargs);
+		va_end(fmtargs);
+		fprintf(stderr, "\n");
+	}
+}
+
+void
+disableoom(void)
+{
+	int fd;
+
+	fd = open("/proc/self/oom_score_adj", O_RDWR);
+	if (fd < 0) {
+		fd = open("/proc/self/oom_adj", O_RDWR);
+		if (fd < 0)
+			edie("disabling oom failed.");
+		write(fd, "-17", 3);
+		close(fd);
+	} else {
+		write(fd, "-1000", 5);
+		close(fd);
+	}
+}
+
+void
+child(char *runpath)
+{
+	int fd, pid;
+
+	if (!(pid = fork())) {
+		if (dofork) {
+			fd = open("/dev/null", O_RDWR);
+			if (fd >= 0) {
+				if (write(0, 0, 0) < 0)
+					dup2(fd, 0);
+				if (write(2, 0, 0) < 0)
+					dup2(fd, 0);
+				if (fd > 2)
+					close(fd);
+			}
+		}
+
+		dbg("running %s", runpath);
+		if (execlp(runpath, basename(runpath), NULL) < 0)
+			edie("execvp");
+		exit(0);
+	}
+	if (pid < 0)
+		edie("fork");
+
+	waitpid(pid, NULL, 0);
+}
+
+void
+sighandler(int sig)
+{
+	switch(sig) {
+	case SIGHUP:
+	case SIGINT:
+	case SIGQUIT:
+	case SIGABRT:
+	case SIGTERM:
+	case SIGKILL:
+		if (listfd >= 0) {
+			shutdown(listfd, SHUT_RDWR);
+			close(listfd);
+		}
+		exit(0);
+		break;
+	default:
+		break;
+	}
+}
+
+void
+initsignals(void)
+{
+	signal(SIGHUP, sighandler);
+	signal(SIGINT, sighandler);
+	signal(SIGQUIT, sighandler);
+	signal(SIGABRT, sighandler);
+	signal(SIGTERM, sighandler);
+	signal(SIGKILL, sighandler);
+
+	signal(SIGCHLD, SIG_IGN);
+	signal(SIGPIPE, SIG_IGN);
+}
+
+void
+usage(void)
+{
+	die("usage: %s [-hdb] [-kl] [-f subsystem] [-r run]\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	struct sockaddr_nl nls;
+	struct pollfd fds;
+	char buf[4097], *subsystem, *runpath, *key, *value;
+	int i, len, slen, showudev, showkernel;
+
+	showkernel = 1;
+	showudev = 1;
+	subsystem = NULL;
+	runpath = "/bin/mdev";
+
+	ARGBEGIN {
+	case 'b':
+		dofork = 1;
+		break;
+	case 'd':
+		dodebug = 1;
+		break;
+	case 'f':
+		subsystem = EARGF(usage());
+		break;
+	case 'k':
+		showudev = 0;
+		break;
+	case 'l':
+		showkernel = 0;
+		break;
+	case 'r':
+		runpath = EARGF(usage());
+		break;
+	default:
+		usage();
+	} ARGEND;
+
+	memset(&nls, 0, sizeof(nls));
+	nls.nl_family = AF_NETLINK;
+	nls.nl_pid = getpid();
+	nls.nl_groups = -1;
+
+	fds.events = POLLIN;
+	fds.fd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
+	listfd = fds.fd;
+	if (fds.fd < 0)
+		edie("socket");
+
+	slen = 128*1024*1024;
+	if (setsockopt(fds.fd, SOL_SOCKET, SO_RCVBUFFORCE, &slen,
+				sizeof(slen)) < 0) {
+		edie("setsockopt");
+	}
+
+	if (bind(fds.fd, (void *)&nls, sizeof(nls)))
+		edie("bind");
+
+	if (dofork) {
+		if (daemon(0, 0) < 0)
+			edie("daemon");
+		umask(022);
+	}
+
+	initsignals();
+	disableoom();
+
+	buf[sizeof(buf)-1] = '\0';
+	while (poll(&fds, 1, -1) > -1) {
+		unsetenv("ACTION");
+		unsetenv("DEVPATH");
+		unsetenv("SUBSYSTEM");
+		unsetenv("SEQNUM");
+		unsetenv("MODALIAS");
+		unsetenv("DEVNAME");
+		unsetenv("DEVTYPE");
+		unsetenv("MAJOR");
+		unsetenv("MINOR");
+		unsetenv("FIRMWARE");
+
+		len = recv(fds.fd, buf, sizeof(buf)-1, MSG_DONTWAIT);
+		if (len < 0)
+			edie("recv");
+
+		if (strstr(buf, "libudev")) {
+			if (!showudev)
+				continue;
+		} else {
+			if (!showkernel)
+				continue;
+		}
+
+		for (i = 0; i < len; i += slen + 1) {
+			key = buf + i;
+			value = strchr(key, '=');
+			slen = strlen(buf+i);
+
+			if (!slen || value == NULL)
+				continue;
+			if (subsystem && !strncmp(key, "SUBSYSTEM=", 10)
+					&& !strstr(key+10, subsystem)) {
+				dbg("subsystem filter '%s' applied.",
+						subsystem);
+				break;
+			}
+
+			value[0] = '\0';
+			value++;
+
+			/*
+			 * We generally trust the kernel. But there
+			 * might be some udev flaw. (It's >20k sloc!)
+			 */
+			if (strcmp(key, "PATH")) {
+				setenv(key, value, 1);
+				dbg("%s = \"%s\"", key, value);
+			}
+		}
+		if (getenv("ACTION") != NULL &&
+				getenv("DEVPATH") != NULL &&
+				getenv("SUBSYSTEM") != NULL &&
+				getenv("SEQNUM") != NULL) {
+			child(runpath);
+		}
+	}
+
+	shutdown(listfd, SHUT_RDWR);
+	close(listfd);
+
+	return 0;
+}
+
-- 
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