lkml.org 
[lkml]   [2004]   [Oct]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Write USB Device Driver entry not called
On Sat, 23 Oct 2004 07:12:56 +0530, eshwar <eshwar@moschip.com> wrote:
> I agree but the return value from the vfs_write should not be the -EBADF
> (Bad File descriptor) it might be -EACCES (premission denied)... Correct me
> if I am wrong...
>
> this can be code in fs/read_write.c vfs_write()
>
> if (!(file->f_mode & FMODE_WRITE))
> return -EACCES;

Wrong. You are confused between file perms & mode of access to files.
If you cannot open a file due to insufficient perms, then EACCESS is
what you get.
If you opened a file for reading, but you tried to write, the you get a EBADF.

Run the following code, after you create two files, 'foo' ( perms 0400
) and 'bar' ( 0700 ).

#include <fcntl.h>

int main()
{
int fd;

fd = open("foo",O_WRONLY);

if(fd < 0)
perror("Opening foo:");
else
close (fd);

fd = open("bar",O_RDONLY);

if(fd < 0)
perror("Opening bar: ");
else {
if(write(fd,'a',1) < 0)
perror("Write to bar failed: ");
close(fd);
}

}

Output would be:
Opening foo:: Permission denied
Write to bar failed: : Bad file descriptor
--
######
raj
######
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 14:07    [W:0.049 / U:7.192 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site