nlplug: refactor to reduce forks

- prepare for loading modaliases with libkmod
- only fork/exec when there is a DEVNAME

2 files changed, 78 insertions, 43 deletions

diff --git a/Makefile b/Makefile
index bbd1213..67347f5 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 
 CFLAGS ?= -Wall -Werror -g
-CFLAGS += -D_GNU_SOURCE
+CFLAGS += -D_GNU_SOURCE -DDEBUG
 
 nlsockd_SRCS = nlsockd.c
 nlsockd_OBJS = $(nlsockd_SRCS:%.c=%.o)
@@ -8,14 +8,17 @@ nlsockd_OBJS = $(nlsockd_SRCS:%.c=%.o)
 nlplug_SRCS = nlplug.c
 nlplug_OBJS = $(nlplug_SRCS:%.c=%.o)
 
-all: nlsockd nlplug
+handler_SRCS = handler.c
+handler_OBJS = $(handler_SRCS:%.c=%.o)
 
-nlsockd: $(nlsockd_OBJS)
+all: nlsockd nlplug handler
 
+nlsockd: $(nlsockd_OBJS)
 nlplug: $(nlplug_OBJS)
+handler: $(handler_OBJS)
 
 
-nlsockd nlplug:
+handler nlsockd nlplug:
 	$(CC) -o $@ $(CFLAGS) $($@_CFLAGS) $($@_OBJS) $(LDFLAGS) $($@_LDFLAGS)
 
 clean:
diff --git a/nlplug.c b/nlplug.c
index ed3dbcd..d8212fb 100644
--- a/nlplug.c
+++ b/nlplug.c
@@ -9,6 +9,7 @@
 #include <err.h>
 #include <errno.h>
 #include <poll.h>
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
@@ -44,13 +45,15 @@ dbg(char *fmt, ...)
 #define dbg(...)
 #endif
 
+static int fork_count = 0, modalias_count = 0, event_count = 0;
+
 void
 run_child(char **argv)
 {
 	pid_t pid;
 
 	if (!(pid = fork())) {
-		dbg("running %s", runpath);
+		dbg("running %s", argv[0]);
 		if (execv(argv[0], argv) < 0)
 			err(1, argv[0]);
 		exit(0);
@@ -59,8 +62,70 @@ run_child(char **argv)
 		err(1,"fork");
 
 	waitpid(pid, NULL, 0);
+	fork_count++;
 }
 
+int process_kbuf(char *buf, const size_t len, char **argv, const char *subsys)
+{
+	char *modalias = NULL;
+
+	int i, slen = 0;
+	char *key, *value;
+
+	clearenv();
+	setenv("PATH", "/sbin:/bin", 1);
+
+	for (i = 0; i < len; i += slen + 1) {
+
+		key = buf + i;
+		value = strchr(key, '=');
+		slen = strlen(buf+i);
+
+		if (!slen) {
+			dbg("=== empty string ===");
+			continue;
+		}
+
+		if (value == NULL) {
+			dbg("=== uevent: '%s'", key);
+			continue;
+		}
+
+		if (subsys && !strncmp(key, "SUBSYSTEM=", 10)
+				&& !strstr(key+10, subsys)) {
+			dbg("subsystem filter '%s' applied.", subsys);
+			break;
+		}
+
+		value[0] = '\0';
+		value++;
+
+		if (!strncmp(key, "MODALIAS", 9))
+			modalias = 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) {
+		if (modalias != NULL)
+			dbg("MODALIAS: %s", modalias);
+		else if (getenv("DEVNAME") != NULL) {
+			run_child(argv);
+/*
+		else if(getenv("DEVPATH") != NULL &&
+			getenv("SUBSYSTEM") != NULL &&
+			getenv("SEQNUM") != NULL) {
+*/
+		}
+	}
+	return modalias != NULL ? 1 : 0;
+}
 
 void
 usage(void)
@@ -103,8 +168,6 @@ int main(int argc, char *argv[])
 	fds.events = POLLIN;
 	while ((r = poll(&fds, 1, EVENT_TIMEOUT)) > 0) {
 		size_t len;
-		int i, slen;
-		char *key, *value;
 		struct iovec iov;
 		char cbuf[CMSG_SPACE(sizeof(struct ucred))];
 		char buf[16384];
@@ -113,9 +176,6 @@ int main(int argc, char *argv[])
 		struct msghdr hdr;
 		struct sockaddr_nl cnls;
 
-		clearenv();
-		setenv("PATH", "/sbin:/bin", 1);
-
 		if (!(fds.revents & POLLIN))
 			continue;
 
@@ -170,39 +230,9 @@ int main(int argc, char *argv[])
 				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) {
-			run_child(argv);
-		}
-
+		modalias_count += process_kbuf(buf, len, argv, subsystem);
+		event_count++;
+		dbg("-------------------------\n");
 		if (fds.revents & POLLHUP) {
 			dbg("parent hung up\n");
 			return 0;
@@ -213,6 +243,8 @@ int main(int argc, char *argv[])
 
 	if (r == 0)
 		dbg("exit due to timeout");
+	dbg("modaliases: %i, forks: %i, events: %i", modalias_count, fork_count,
+		event_count);
 
 	return 0;
 }