Re: Problem parsing %s in udev rules

[Andrew Patterson <andrew.patterson@hp.com>]

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Kay,

On Thu, 2004-10-07 at 02:30 +0200, Kay Sievers wrote:
> On Wed, Oct 06, 2004 at 06:23:05PM -0600, Andrew Patterson wrote:
> > On Thu, 2004-10-07 at 01:50 +0200, Kay Sievers wrote:
> > > On Wed, Oct 06, 2004 at 05:33:04PM -0600, Andrew Patterson wrote:
> > > > Udev seems to be chopping off anything seen in a rule after a %s.  For
> > > > example, if I have the following rule:
> > > > 
> > > > BUS="scsi", KERNEL="sd*", PROGRAM="/sbin/scsi_id", NAME="%k",
> > > > SYMLINK="scsi_disks/some-proceeding-stuff-%s{model}-some-following-
> > > > stuff"
> > > > 
> > > > Everything after the %s{model} is ignored.
> > > > 
> > > > Furthermore, everything in model following whitespace is ignored as
> > > > well.  I.e, if model contains "HP 34.7G", the resulting device file
> > > > created is /dev/scsi_disks/some-proceeding-stuff-HP.
> > > > 
> > > > I used the following command to run this test:
> > > > 
> > > > # DEVPATH=/block/sda ACTION=add ./udev block
> > > > 
> > > > I also get the same behavior when using udevstart (patched to fix
> > > > parameter passing problems).
> > > 
> > > If your sysfs value contains spaces, which is the delimiter for multiple
> > > symlinks, it will not work.
> > > 
> > > udev can't do this now, you need to wrap the call with an external script,
> > > which ensures sane values.
> > > 
> > 
> > That explains the spaces.  What about stuff trailing %s, if %s does not
> > contain spaces.  I.e, in the above example, model is ST336753LC and the
> > resulting device file is /dev/scsi_disks/some-proceding-stuff-
> > ST336753LC.
> 
> I expect the model value has trailing spaces.
> 
> You may look with:
>   udevinfo -a -p /block/sdX

Yes it does, and it seems for most SCSI devices, vendor and model will
have trailing spaces.  I have included a patch to udev-036 to deal with
this issue.  It trims off trailing whitespace for all sysfs attributes.
It might be better to trim off leading whitespace as well.  

I also wonder if it might be a good idea to do some sort of
transformation for characters in an attribute that are illegal in a file
system, rather than just chopping everything off. e.g, spaces that are
not leading or trailing would be changed to underscores.

Andrew

> 
> Kay
> 
-- 
Andrew Patterson                
Hewlett-Packard

diff -Nur udev-036.orig/namedev.c udev-036/namedev.c
--- udev-036.orig/namedev.c	2004-10-12 14:52:18.000000000 -0600
+++ udev-036/namedev.c	2004-10-12 16:51:05.000000000 -0600
@@ -511,7 +511,7 @@
 static struct sysfs_attribute *find_sysfs_attribute(struct sysfs_class_device *class_dev, struct sysfs_device *sysfs_device, char *attr)
 {
 	struct sysfs_attribute *tmpattr = NULL;
-	char *c;
+	int endidx;
 
 	dbg("look for device attribute '%s'", attr);
 	/* try to find the attribute in the class device directory */
@@ -529,9 +529,9 @@
 	return NULL;
 
 attr_found:
-	c = strchr(tmpattr->value, '\n');
-	if (c != NULL)
-		c[0] = '\0';
+	endidx = strcspn(tmpattr->value, " \t\n");
+	if (endidx > 0)
+		tmpattr->value[endidx - 1] = '\0';
 
 	dbg("found attribute '%s'", tmpattr->path);
 	return tmpattr;


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