Re: Two questions regarding Opening files within Kernel!

[Jan Engelhardt <jengelh@linux01.gwdg.de>]

On Apr 7 2007 06:58, JanuGerman wrote:
>Hi Every one,
>
>  I have got two questions regarding opening files within the Linux 
>  kernel. If some body can help me, in sorting out this problem, i will 
>  be very thankful.
>
>1)   I have just a file path with me, an absolute path, but no dentry, 
>   no inode, no vfsmount object, which function i can call to get a 
>   "file" object associated with the absoulte file path. I have surfed 
>   arround the source code especially fs/open.c and some other files, 
>   but each function requires a parameter "mode" and "fd" beside file 
>   path. Actually, i was confuse about the "mode" parameter (and its 
>   differece with "flag"), like what to send, and secondly for "fd", i 
>   am not sure, what value to send as there is no file infact and only 
>   file path exists. Any idea?

Not sure if this is the right function, but it should get you started...

struct dentry *foooobar = lookup_one_len("/foo/bar", current->fs->root);

>2) Any functionality within linux kernel source code, to read one line 
>   per file? or some indirect way to set buffer size for one read?. 
>   That is, any existing header file for doing text I/O rather than 
>   binary within the kernel source code?

http://kernelnewbies.org/FAQ/WhyWritingFilesFromKernelIsBad
(same goes for reading)


Jan
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