Re: [PATCH] udev - advanced user query options

[Kay Sievers <kay.sievers@vrfy.org>]

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On Mon, Jan 12, 2004 at 01:21:30PM -0800, Greg KH wrote:
> On Sun, Jan 11, 2004 at 03:33:00AM +0100, Kay Sievers wrote:
> > This patch improves the user options for udev.
> > It is possible now to query for the name, the symlinks or owner/group.
> > If asked for the name of the node we are able to prepend the udev_root
> > with the -r option.
> > 
> > SAMPLE:
> > 
> >   kay@pim:~/src/udev.test$ ./udev -V
> >   udev, version 012_bk
> > 
> >   kay@pim:~/src/udev.test$ ./udev -h
> >   Usage: [-qrVh]
> >     -q <name>  query database for the specified value
> >     -p <path>  device path used for query
> >     -r         print udev root
> >     -V         print udev version
> >     -h         print this help text
> > 
> >   kay@pim:~/src/udev.test$ ./udev -r
> >   /udev/
> > 
> >   kay@pim:~/src/udev.test$ ./udev -q name -p /class/video4linux/video0
> >   video/webcam0
> > 
> >   kay@pim:~/src/udev.test$ ./udev -q symlink -p /class/video4linux/video0
> >   camera0 kamera0
> > 
> >   kay@pim:~/src/udev.test$ ./udev -q owner -p /class/video4linux/video0
> >   501
> > 
> >   kay@pim:~/src/udev.test$ ./udev -r -q name -p /class/video4linux/video0
> >   /udev/video/webcam0
> 
> Very nice, applied, thanks.
> 
> Hm, care to update the man page with this information, and the '-h'
> option to explain queries a bit more?

Yes, I'll take the man page in the next two hours.

Here is the '-h' and a '-d' to dump the whole database:

  kay@pim:~/src/udev.kay$ ./udev -d
  P: /block/hdb/hdb1
  N: hdb1
  S: 
  O: 
  G: 

  P: /class/video4linux/video0
  N: video/webcam0
  S: camera0 kamera0
  O: 500
  G: 500

  P: /block/hdc
  N: hdc
  S: 
  O: 
  G: 

thanks,
Kay

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diff -Nru a/udev.c b/udev.c
--- a/udev.c	Tue Jan 13 00:40:56 2004
+++ b/udev.c	Tue Jan 13 00:40:56 2004
@@ -82,6 +82,16 @@
 	return seqnum;
 }
 
+static void print_record(char *path, struct udevice *dev)
+{
+	printf("P: %s\n", path);
+	printf("N: %s\n", dev->name);
+	printf("S: %s\n", dev->symlink);
+	printf("O: %s\n", dev->owner);
+	printf("G: %s\n", dev->group);
+	printf("\n");
+}
+
 enum query_type {
 	NONE,
 	NAME,
@@ -92,7 +102,7 @@
 
 static inline int udev_user(int argc, char **argv)
 {
-	static const char short_options[] = "p:q:rVh";
+	static const char short_options[] = "dp:q:rVh";
 	int option;
 	int retval = -EINVAL;
 	struct udevice dev;
@@ -144,6 +154,16 @@
 			root = 1;
 			break;
 
+		case 'd':
+			retval = udevdb_open_ro();
+			if (retval != 0) {
+				printf("unable to open udev database\n");
+				return -EACCES;
+			}
+			retval = udevdb_dump(print_record);
+			udevdb_exit();
+			return retval;
+
 		case 'V':
 			printf("udev, version %s\n", UDEV_VERSION);
 			return 0;
@@ -206,12 +226,17 @@
 	}
 
 help:
-	printf("Usage: [-qrVh]\n"
-	       "  -q <name>  query database for the specified value\n"
-	       "  -p <path>  device path used for query\n"
-	       "  -r         print udev root\n"
-	       "  -V         print udev version\n"
-	       "  -h         print this help text\n"
+	printf("Usage: [-pqrdVh]\n"
+	       "  -q TYPE  query database for the specified value:\n"
+	       "             'name'    name of device node\n"
+	       "             'symlink' pointing to node\n"
+	       "             'owner'   of node\n"
+	       "             'group'   of node\n"
+	       "  -p PATH  sysfs device path used for query\n"
+	       "  -r       print udev root\n"
+	       "  -d       dump whole database\n"
+	       "  -V       print udev version\n"
+	       "  -h       print this help text\n"
 	       "\n");
 	return retval;
 }
diff -Nru a/udevdb.c b/udevdb.c
--- a/udevdb.c	Tue Jan 13 00:40:56 2004
+++ b/udevdb.c	Tue Jan 13 00:40:56 2004
@@ -124,7 +124,7 @@
 			dbg("unable to initialize in-memory database");
 		else
 			dbg("unable to initialize database at '%s'", udev_db_filename);
-		return -EINVAL;
+		return -EACCES;
 	}
 	return 0;
 }
@@ -137,7 +137,30 @@
 	udevdb = tdb_open(udev_db_filename, 0, 0, O_RDONLY, 0);
 	if (udevdb == NULL) {
 		dbg("unable to open database at '%s'", udev_db_filename);
+		return -EACCES;
+	}
+	return 0;
+}
+
+void (*user_record_callback) (char *path, struct udevice *dev);
+
+static int traverse_callback(TDB_CONTEXT *tdb, TDB_DATA key, TDB_DATA dbuf, void *state)
+{
+	user_record_callback((char*) key.dptr, (struct udevice*) dbuf.dptr);
+	return 0;
+}
+
+/**
+ * udevdb_dump: dumps whole database by passing record data to user function
+ * @user_record_handler: user function called for every record in the database
+ */
+int udevdb_dump(void (*user_record_handler) (char *path, struct udevice *dev))
+{
+	if (user_record_handler == NULL) {
+		dbg("invalid user record handling function");
 		return -EINVAL;
 	}
+	user_record_callback = user_record_handler;
+	tdb_traverse(udevdb, traverse_callback, NULL);
 	return 0;
 }
diff -Nru a/udevdb.h b/udevdb.h
--- a/udevdb.h	Tue Jan 13 00:40:56 2004
+++ b/udevdb.h	Tue Jan 13 00:40:56 2004
@@ -12,6 +12,7 @@
 extern void udevdb_exit(void);
 extern int udevdb_init(int init_flag);
 extern int udevdb_open_ro(void);
+extern int udevdb_dump(void (*user_record_handler) (char *path, struct udevice *dev));
 
 extern int udevdb_add_dev(const char *path, const struct udevice *dev);
 extern int udevdb_get_dev(const char *path, struct udevice *dev);