My thoughts ... cat >> /dev/CharDev0 should open the device in append mode flag, and your code will set the file pointer to the size. It is up to you to honour the file position field ( f_pos) in your device read and device write functions. Also I think you should increment the file positions your own after read and write. Since it is a device file I do not think kernel is going to execute any file system's file or inode operations. I guess you will have implement all these operations on your own. Aboo -----Original Message----- From: kernelnewbies-bounce@xxxxxxxxxxxx [mailto:kernelnewbies-bounce@xxxxxxxxxxxx] On Behalf Of Dinesh Ahuja Sent: Sunday, October 10, 2004 11:17 PM To: kernelnewbies@xxxxxxxxxxxx Subject: Appending functionality in Character Device Driver I want to provide a appending functionality in a character device driver and I have done the following thing in a device_open function. if (pfile->f_flags & O_APPEND) { // Opening a device file in Append Mode. printk("<1> Append Flag has been Used\n"); pfile->f_pos = pdevice_data->size; } else if ((pfile->f_flags & O_ACCMODE) == O_WRONLY) { // Opening a device file in Write Mode if (pdevice_data->data) { kfree(pdevice_data->data); pdevice_data->data = NULL; pdevice_data->size = 0; } } In this , pdevice_data is a pointer to Device_Data structure which is defined as follows: typedef struct Device_Data { void * data; unsigned long size; unsigned long max_size; }Device_Data; Is my approach fine and is it fine If I modify on my own pfile->f_pos in the device_open ? Is there any way by which Kernel takes cares of this on its own and set the file position at the end of the file when I use the following commmand cat >> /dev/CharDev0 Regards Dinesh ________________________________________________________________________ Yahoo! India Matrimony: Find your life partner online Go to: http://yahoo.shaadi.com/india-matrimony -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/ -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
