Cleaning up FILE in stdio..

[John Baldwin]

On Wednesday 27 February 2008 01:54:46 pm Garrett Wollman wrote:
> <<On Wed, 27 Feb 2008 11:34:04 -0500, John Baldwin <jhb at freebsd.org> said:
> 
> > I avoided EMFILE in all 3 cases as it struck me as being not really true 
(an 
> > app would find the rlimit higher than the current fd for example).  Also, 
> > EMFILE doesn't really make sense from fdopen() at all.  You've already 
opened 
> > the fd, so you know you can't run out of fd's.
> 
> [EMFILE] is does not imply that you have run out of fds.  POSIX
> says (for fdopen()):
> 
> The fdopen( ) function may fail if:
> [EBADF]            The fildes argument is not a valid file descriptor.
> [EINVAL]           The mode argument is not a valid mode.
> [EMFILE]           {FOPEN_MAX} streams are currently open in the
>                    calling process.
> [EMFILE]           {STREAM_MAX} streams are currently open in the
>                    calling process.
> [ENOMEM]           Insufficient space to allocate a buffer.
> 
> My change to sysconf() causes {STREAM_MAX} to be clamped at
> {SHRT_MAX}, so a user calling sysconf(_PC_STREAM_MAX) or
> $(getconf STREAM_MAX) will see a different value from the resource
> limit and understand that there is a limit (even if it's not quite on
> the number of streams).
> 
> For fopen(), the errors are defined as follows:
> 
> "shall fail":
> [EMFILE] {OPEN_MAX} file descriptors are currently open in the calling
> process.
> [ENFILE] The maximum allowable number of files is currently open in
> the system.
> 
> "may fail":
> [EINVAL] The value of the mode argument is not valid.
> [EMFILE] {FOPEN_MAX} streams are currently open in the calling
> process.
> [EMFILE] {STREAM_MAX} streams are currently open in the calling
> process.
> 
> The other possibility would be [EOVERFLOW], which is defined as:
> 
> [EOVERFLOW] The named file is a regular file and the size of the file
>             cannot be represented correctly in an object of type off_t.
> 
> But I truly believe that [EMFILE] is the best option.

Ok.  I was going based on our manpages, but I will happily use EMFILE instead 
given this.  I will commit the temp fix today so we can MFC it.

-- 
John Baldwin