Re: [PATCH] Input: atmel_mxt_ts - Use snprintf for sysfs attribute show method

Hi Joonyoung,

Thanks for replying.

On Fri, Sep 16, 2011 at 8:52 AM, Joonyoung Shim [off-list ref] wrote:

Hi,

On 2011-09-16 오전 4:40, Daniel Kurtz wrote:

quoted

Sysfs attribute show methods are always passed a buffer of length
PAGE_SIZE.  To keep from overwriting this buffer and causing havoc, use
snprintf() to guarantee we never write more than the buffer can hold.

In addition, at least for my touchscreen, the number and size of objects
was far too big to fit in a single 4K page.  Therefore, this patch also
trims some redundant framing text to leave more room for actual data.

Signed-off-by: Daniel Kurtz<redacted>

This patch is working but original problem is object size is increasing
as atmel touchscreen chip updates and we should consider also the
instances of object.

"This patch is working" = Acked-By ?

How about splitting attributes to each object?

I agree.  Can we do that in another patch (with instance printing)?

Iiro, do you have any update plans about atmel touchscreen driver?

I have several more patches coming for this driver, mostly to speed up
startup time, cleanup the MT-B implementation, and optimize interrupt
handling.

Thanks,
Daniel

quoted

---
 drivers/input/touchscreen/atmel_mxt_ts.c |   21 +++++++++++++++------
 1 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c

b/drivers/input/touchscreen/atmel_mxt_ts.c
index f5d6685..a596c27 100644

--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c

@@ -910,12 +910,17 @@ static ssize_t mxt_object_show(struct device *dev,

       for (i = 0; i<  data->info.object_num; i++) {
               object = data->object_table + i;

-               count += sprintf(buf + count,
-                               "Object Table Element %d(Type %d)\n",
+               count += snprintf(buf + count, PAGE_SIZE - count,
+                               "Object[%d] (Type %d)\n",
                               i + 1, object->type);
+               if (count>= PAGE_SIZE)
+                       return PAGE_SIZE - 1;

               if (!mxt_object_readable(object->type)) {
-                       count += sprintf(buf + count, "\n");
+                       count += snprintf(buf + count, PAGE_SIZE - count,
+                                       "\n");
+                       if (count>= PAGE_SIZE)
+                               return PAGE_SIZE - 1;
                       continue;
               }

@@ -925,11 +930,15 @@ static ssize_t mxt_object_show(struct device *dev,

                       if (error)
                               return error;

-                       count += sprintf(buf + count,
-                                       "  Byte %d: 0x%x (%d)\n", j, val,
val);
+                       count += snprintf(buf + count, PAGE_SIZE - count,
+                                       "\t[%2d]: %02x (%d)\n", j, val,
val);
+                       if (count>= PAGE_SIZE)
+                               return PAGE_SIZE - 1;
               }

-               count += sprintf(buf + count, "\n");
+               count += snprintf(buf + count, PAGE_SIZE - count, "\n");
+               if (count>= PAGE_SIZE)
+                       return PAGE_SIZE - 1;
       }

       return count;