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Re: fdopen and errno


Momchil 'Velco' Velikov wrote:

> Mark Kettenis wrote:
> > to indicate the error.  Thus for Unix98 compatibility we should
> > probably set errno.  It looks as if we already detect EBADF and ENOMEM (I
> > don't think we will ever encounter a condition that should generate
> > EMFILE in glibc), and EINVAL in the case of a totally bogus mode
> > specification.  We should probably set errno to EINVAL as well if the
> > stream mode doesn't match the access mode.
> I'd suggest to set the errno to EBADF in order to be consistent
> with other functions, which report an error on incompatible open mode.
> Some of these functions are read(2) and write(2).
> Also, stdio sets EBADF in this case.
> IMHO, EINVAL is more applicable to bogus arguments, e.g. mode == "ix".

It would be more informative if fdopen() could distinguish between the cases:

EBADF      - Not an open file descriptor
EACCES   -  Requested access mode incompatible with file descriptor mode

Although unfortunately read(2), write(2) don't make any such distinction.

Ben



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