[PATCH] Creating nodes actually works.

udev.c

@@ -23,6 +23,11 @@
 
 #include <stdlib.h>
 #include <string.h>
+#include <stdio.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+
 #include "udev.h"
 #include "udev_version.h"
 
@@ -36,11 +41,9 @@ static char *get_action(void)
 }
 
 
-/* yeah this should be dynamically allocated... */
-static char device[255];
-
 static char *get_device(void)
 {
+	static char device[255];
 	char *temp;
 
 	temp = getenv("DEVPATH");
@@ -52,32 +55,216 @@ static char *get_device(void)
 	return device;
 }
 
+/* 
+ * Right now the major/minor of a device is stored in a file called
+ * "dev" in sysfs.
+ * The number is stored as:
+ * 	MMmm
+ * 		MM is the major
+ * 		mm is the minor
+ * 		The value is in hex.
+ * Yes, this will probably change when we go to a bigger major/minor
+ * range, and will have to be changed at that time.
+ */
+static int get_major_minor (char *dev, int *major, int *minor)
+{
+	char filename[255];
+	char line[20];
+	char temp[3];
+	int fd;
+	int retval = 0;
+
+	/* add the dev file to the directory and see if it's present */
+	strncpy(filename, dev, sizeof(filename));
+	strncat(filename, DEV_FILE, sizeof(filename));
+	fd = open(filename, O_RDONLY);
+	if (fd < 0) {
+		dbg("Can't open %s", filename);
+		return -ENODEV;
+	}
+
+	/* get the major/minor */
+	retval = read(fd, line, sizeof(line));
+	if (retval < 0) {
+		dbg("read error on %s", dev);
+		goto exit;
+	}
+
+	temp[0] = line[0];
+	temp[1] = line[1];
+	temp[2] = 0x00;
+	*major = (int)strtol(&temp[0], NULL, 16);
+
+	temp[0] = line[2];
+	temp[1] = line[3];
+	temp[2] = 0x00;
+	*minor = (int)strtol(&temp[0], NULL, 16);
+
+	dbg("found major = %d, minor = %d", *major, *minor);
+
+	retval = 0;
+exit:
+	close(fd);
+	return retval;
+}
+
+/*
+ * Here would go a call to the naming deamon, to get the name we want to have
+ * for this device.  But for now, let's just default to whatever the kernel is
+ * calling the device as that will keep the "old-style" naming policy
+ */
+static char *get_name(char *dev, int major, int minor)
+{
+	static char name[100];
+	char *temp;
+
+	temp = strrchr(dev, '/');
+	if (temp == NULL)
+		return NULL;
+	strncpy(name, &temp[1], sizeof(name));
+
+	dbg("name is %s", name);
+
+	return &name[0];
+}
+
+/*
+ * Again, this will live in the naming deamon
+ */
+static int get_mode(char *name, char *dev, int major, int minor)
+{
+	/* just default everyone to rw for the world! */
+	return 0666;
+}
+
+/*
+ * We also want to add some permissions here, and possibly some symlinks
+ */
+static int create_node(char *name, char type, int major, int minor, int mode)
+{
+	char *argv[7];
+	char mode_string[100];
+	char type_string[3];
+	char major_string[20];
+	char minor_string[20];
+	char filename[255];
+	int retval = 0;
+
+	strncpy(filename, UDEV_ROOT, sizeof(filename));
+	strncat(filename, name, sizeof(filename));
+
+	snprintf(mode_string, sizeof(mode_string), "--mode=%#o", mode);
+	snprintf(type_string, sizeof(type_string), "%c", type);
+	snprintf(major_string, sizeof(major_string), "%d", major);
+	snprintf(minor_string, sizeof(minor_string), "%d", minor);
+	
+	argv[0] = MKNOD;
+	argv[1] = mode_string;
+	argv[2] = filename;
+	argv[3] = type_string;
+	argv[4] = major_string;
+	argv[5] = minor_string;
+	argv[6] = NULL;
+	dbg ("executing %s %s %s %s %s %s",
+		argv[0], argv[1], argv[2], argv[3], argv[4], argv[5]);
+	switch (fork()) {
+		case 0:
+			/* we are the child, so lets run the program */
+			execv (MKNOD, argv);
+			exit(0);
+			break;
+		case (-1):
+			dbg ("fork failed.");
+			retval = -EFAULT;
+			break;
+		default:
+			break;
+	}
+	return retval;
+}
+
+static int remove_node(char *name)
+{
+	return 0;
+}
+
+static int do_it(char *action, char *name, char type, int major, int minor, int mode)
+{
+	if (strcmp(action, "add") == 0)
+		return create_node(name, type, major, minor, mode);
+
+	if (strcmp(action, "remove") == 0)
+		return remove_node(name);
+
+	dbg("Unknown action: %s", action);
+	return -EINVAL;
+}
 
 int main(int argc, char *argv[])
 {
 	char *subsystem;
 	char *action;
-	char *dev;
+	char *device;
+	char *name;
+	char type;
+	int major;
+	int minor;
+	int mode;
+	int retval = -EINVAL;
 	
 	if (argc != 2) {
 		dbg ("unknown number of arguments");
-		return 1;
+		goto exit;
 	}
 
+	/* for now, the block layer is the only place where block devices are */
 	subsystem = argv[1];
+	if (strcmp(subsystem, "block") == 0)
+		type = 'b';
+	else
+		type = 'c';
 
 	action = get_action();
 	if (!action) {
 		dbg ("no action?");
-		return 1;
+		goto exit;
 	}
 
-	dev = get_device();
-	if (!dev) {
+	device = get_device();
+	if (!device) {
 		dbg ("no device?");
-		return 1;
+		goto exit;
+	}
+	dbg("looking at %s", device);
+
+	retval = get_major_minor(device, &major, &minor);
+	if (retval) {
+		dbg ("get_major_minor failed");
+		goto exit;
 	}
 
-	return 0;
+	name = get_name(device, major, minor);
+	if (name == NULL) {
+		dbg ("get_name failed");
+		retval = -ENODEV;
+		goto exit;
+	}
+
+	mode = get_mode(name, device, major, minor);
+	if (mode < 0) {
+		dbg ("get_mode failed");
+		retval = -EINVAL;
+		goto exit;
+	}
+
+	retval = do_it(action, name, type, major, minor, mode);
+	if (retval) {
+		dbg ("do_it failed");
+		goto exit;
+	}
+
+	retval = 0;
+exit:	
+	return retval;
 }
 

udev.h

@@ -36,10 +36,21 @@
 
 
 /* Lots of constants that should be in a config file sometime */
+
+/* Location of sysfs mount */
 #define SYSFS_ROOT	"/sys"
+
+/* Where udev should create its device nodes, trailing / needed */
+#define UDEV_ROOT	"/home/greg/linux/udev/"
+
+/* device file in sysfs that contains major/minor number, leading / needed */
+#define DEV_FILE	"/dev"
+
+/* Binaries that udev calls to do stuff */
 #define MKNOD		"/bin/mknod"
 
 
+
 extern int log_message (int level, const char *format, ...);