[PATCH] fix whitespace handling on sysfs attributes

[PATCH] fix whitespace handling on sysfs attributes

[Jon Smirl]

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The first version of this patch didn't allow for the request firmware
case which does multiple parsing passes on the parameter. This was
discussed in the thread '2.6.13-rc6-mm1'

gregkh-driver-sysfs-strip_leading_trailing_whitespace-3.patch
  should replace in 2.6.13-rc6-mm1
gregkh-driver-sysfs-strip_leading_trailing_whitespace.patch

Signed-off-by: Jon Smirl <jonsmirl@gmail.com>

-- 
Jon Smirl
jonsmirl@gmail.com

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diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -6,6 +6,7 @@
 #include <linux/fsnotify.h>
 #include <linux/kobject.h>
 #include <linux/namei.h>
+#include <linux/ctype.h>
 #include <asm/uaccess.h>
 #include <asm/semaphore.h>
 
@@ -207,8 +208,41 @@ flush_write_buffer(struct dentry * dentr
 	struct attribute * attr = to_attr(dentry);
 	struct kobject * kobj = to_kobj(dentry->d_parent);
 	struct sysfs_ops * ops = buffer->ops;
+	size_t ws_count = count, leading = 0;
+	int ret = 0;
+	char *x;
 
-	return ops->store(kobj,attr,buffer->page,count);
+	/* locate trailing white space */
+	while ((ws_count > 0) && isspace(buffer->page[ws_count - 1]))
+		ws_count--;
+	if (ws_count == 0)
+		return count;
+
+	/* locate leading white space */
+	x = buffer->page;
+	while (isspace(*x))
+		x++;
+	leading = x - buffer->page;
+	ws_count -= leading;
+
+	/* interface is still ambigous about this */
+	/* string is both passed by length and terminated */
+	if (ws_count != PAGE_SIZE)
+		x[ws_count] = '\0';
+
+	ret = ops->store(kobj, attr, x, ws_count);
+
+	/* is it an error? */
+	if (ret < 0) 
+		return ret;
+
+	/* the whole string was consumed */
+	if (ret == ws_count)
+		return count;
+
+	/* only part of the string was consumed */
+	/* return count can not include trailing space */
+	return leading + ret;
 }
 
 

Re: [PATCH] fix whitespace handling on sysfs attributes

[Pavel Machek]

Hi!

> The first version of this patch didn't allow for the request firmware
> case which does multiple parsing passes on the parameter. This was
> discussed in the thread '2.6.13-rc6-mm1'

I still thing this is very wrong to do. sysfs should not try to outguess users.



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