[Patch] Selective removal mode for udev

[Hannes Reinecke <hare@suse.de>]

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Because we are chicken ...

This patch adds a 'removal' mode for udev, with three possible choices:

- all: default behaviour; remove all nodes and symlinks
- symlink_only: only remove symlinks, but keep device nodes
- none: do not remove nodes nor symlinks.

The latter is equivalent with the existing 'ignore_remove' rule 
statement, but implemented as a global switch.

Properly documented in the man-page etc.

This is basically for those worrying about 'my device node may be 
vanishing and ooh everything will stop working'.

Comments etc welcome.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke			hare@suse.de
SuSE Linux AG				S390 & zSeries
Maxfeldstraße 5				+49 911 74053 688
90409 Nürnberg				http://www.suse.de

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===== udev.8.in 1.77 vs edited =====
--- 1.77/udev.8.in	2005-02-10 01:03:54 +01:00
+++ edited/udev.8.in	2005-02-11 09:41:11 +01:00
@@ -59,6 +59,21 @@
 The switch to enable/disable logging of udev information
 The default value is
 .IR yes .
+.TP
+.B udev_remove
+Configure the behaviour for remove events. Possible values are
+.IR all ,
+.IR symlinks_only ,
+.IR none .
+When set to
+.IR all ,
+udev will remove all device information (this is the default). When
+set to
+.IR symlinks_only ,
+udev will remove all symlinks but leave the device node
+intact. When set to
+.IR none ,
+udev will not remove any device information.
 .P
 .RI "A sample " udev.conf " file might look like this:
 .sp
===== udev_config.c 1.31 vs edited =====
--- 1.31/udev_config.c	2005-01-04 21:37:01 +01:00
+++ edited/udev_config.c	2005-02-11 10:04:16 +01:00
@@ -48,6 +48,7 @@
 int udev_log;
 int udev_dev_d;
 int udev_hotplug_d;
+int udev_remove_mode = UDEV_REMOVE_ALL;
 
 
 static int string_is_true(const char *str)
@@ -164,6 +165,17 @@
 
 		if (strcasecmp(variable, "udev_log") == 0) {
 			udev_log = string_is_true(value);
+			continue;
+		}
+
+		if (strcasecmp(variable, "udev_remove") == 0) {
+			if (strcasecmp(value,"all") == 0) {
+				udev_remove_mode=UDEV_REMOVE_ALL;
+			} else if (strcasecmp(value,"symlinks_only") == 0) {
+				udev_remove_mode=UDEV_REMOVE_SYMLINKS;
+			} else if (strcasecmp(value,"none")) {
+				udev_remove_mode=UDEV_REMOVE_NONE;
+			}
 			continue;
 		}
 	}
===== udev_db.c 1.41 vs edited =====
--- 1.41/udev_db.c	2005-02-04 18:38:55 +01:00
+++ edited/udev_db.c	2005-02-11 09:45:54 +01:00
@@ -165,6 +165,11 @@
 	get_db_filename(udev, filename, SYSFS_PATH_MAX);
 	unlink(filename);
 
+	if (udev_remove_mode == UDEV_REMOVE_SYMLINKS) {
+		memset(udev->symlink, 0, NAME_SIZE);
+		udev_db_add_device(udev);
+	}
+
 	return 0;
 }
 
===== udev.h 1.84 vs edited =====
--- 1.84/udev.h	2005-02-09 00:43:18 +01:00
+++ edited/udev.h	2005-02-11 09:32:14 +01:00
@@ -48,6 +48,11 @@
 
 #define DEFAULT_PARTITIONS_COUNT	15
 
+/* Removal modes to keep whiners happy */
+#define UDEV_REMOVE_ALL			0
+#define UDEV_REMOVE_SYMLINKS		1
+#define UDEV_REMOVE_NONE		2
+
 struct udevice {
 	char devpath[DEVPATH_SIZE];
 	char subsystem[SUBSYSTEM_SIZE];
@@ -89,5 +94,6 @@
 extern int udev_log;
 extern int udev_dev_d;
 extern int udev_hotplug_d;
+extern int udev_remove_mode;
 
 #endif
===== udev_remove.c 1.45 vs edited =====
--- 1.45/udev_remove.c	2005-02-09 00:43:18 +01:00
+++ edited/udev_remove.c	2005-02-11 10:07:52 +01:00
@@ -80,6 +80,11 @@
 	snprintf(filename, NAME_SIZE, "%s/%s", udev_root, udev->name);
 	filename[NAME_SIZE-1] = '\0';
 
+	if (udev_remove_mode == UDEV_REMOVE_SYMLINKS) {
+		dbg("remove device nodes for '%s' requested to be ignored by config", udev->name);
+		goto remove_symlinks;
+	}
+
 	info("removing device node '%s'", filename);
 	retval = unlink_secure(filename);
 	if (retval)
@@ -104,6 +109,7 @@
 	if (strchr(udev->name, '/'))
 		delete_path(filename);
 
+ remove_symlinks:
 	foreach_strpart(udev->symlink, " ", pos, len) {
 		char linkname[NAME_SIZE];
 
@@ -152,6 +158,11 @@
 
 	if (udev->ignore_remove) {
 		dbg("remove event for '%s' requested to be ignored by rule", udev->name);
+		return 0;
+	}
+
+	if (udev_remove_mode == UDEV_REMOVE_NONE) {
+		dbg("remove event for '%s' requested to be ignored by config", udev->name);
 		return 0;
 	}