From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jonathan Larmour To: Masaki Sawanobori Cc: ecos-discuss@sourceware.cygnus.com Subject: Re: [ECOS] I/O driver lookup handler: read/write mode Date: Tue, 30 Nov 1999 07:36:00 -0000 Message-id: <3843EEE1.26F8019@cygnus.co.uk> References: <062c01bf3b22$2a8be000$437201aa@atlantis7> X-SW-Source: 1999-11/msg00080.html Masaki Sawanobori wrote: > > I am implementing a simple flash memory file system in the framework of eCos > I/O device driver model and C language libc stdio module so the user can > access a file using fopen() as follows. > > FILE *fp = fopen("/dev/flash0/filename", "r"); > FILE *fp = fopen("/flash0/filename", "w"); Gosh. That's good. Are you considering contributing it back? > The problem is that the second paramter(read/write mode) of fopen() is not > passed down to a "lookup" device driver handler(via the cyg_io_lookup > function). The "lookup" handler has no way of returning a correct > return/error value without knowing whether a file(existing or non-existing) > is for read or write. > > I would not like to resort to a workaround of adding a read/write mode > specifier as part of a filename parameter like "/nvram/filename/w" or > "/nvram/filename/r" or "/nvramR"/filename" or "/nvramW/filename". This > would be redundant for fopen(). Quite, although it wouldn't need to be passed that way for fopen, only cyg_io_lookup. > Is there any other workaround or a solution for this situation? Am I missing > something ? Using cyg_io_get_config() after the cyg_io_lookup() would seem a better approach. > Here is another wish about I/O device driver handlers. There is no "close" > handler. I could use a "close" handler since it seems to be a right place > to free memory allocated in my "lookup" handler. This is true. We intend to do something about that in the eCos implementation of EL/IX, but that may take some time. We intend to do pluggable filesystems as well, so everything should get sorted out eventually. Jifl -- Cygnus Solutions, 35 Cambridge Place, Cambridge, UK. Tel: +44 (1223) 728762 "I used to have an open mind but || Get yer free open source RTOS's here... my brains kept falling out." || http://sourceware.cygnus.com/ecos Help fight spam! http://spam.abuse.net/ These opinions are all my own fault