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    SubjectRe: 2.6.13-rc6-mm1
    On 8/22/05, Benoit Boissinot <benoit.boissinot@ens-lyon.org> wrote:
    > On Sun, Aug 21, 2005 at 06:34:48PM -0400, Jon Smirl wrote:
    > > This should fix it, but I'm not on a machine where I can test it. Can
    > > you give it a try and let me know?
    > >
    >
    > it works ok.
    > But there is still at least one problem: if ops->store returns an error,
    > then there will be a substraction and the write will loop (i could do it
    > with a store wich returned EINVAL and a 22 length string).
    >
    > I don't know if you can put a '\0' at buffer->page[count] if
    > count == PAGE_SIZE.
    >
    > Moreover, i think it is more correct to add only the leading
    > whitespace from the count because if the ops->store doesn't read
    > everything it will do something weird:
    >
    > For example, if we have ' 123 ' and ops->store read only one char,
    > then the function will return 7 (1 leading + 4 trailing + 1 read). For
    > the next call the buffer will be filled only by spaces which is
    > incorrect (it should be '23 ').

    The attached version tries to fix these issues. I am still not
    somewhere where I can test, so please check it out.

    --
    Jon Smirl
    jonsmirl@gmail.com
    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;
    }

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