PATCH: Avoid accidentally opening files for write

[Nick Clifton]

Hi Mark,

>> patch to a generic part of BFD it would be good if you could also test 
>> with a --enable-targets=all build, just to make sure.

> I didn't know about that, but will try it before check-in. 

Thanks.

> Just a build, or should I try to run some kind of testsuite as well?

Just a build, since there will no binutils executable which will 
exercise the new code anyway.  (You could run a GDB testsuite with a 
patched GDB linked against the BFD library built for an all targets 
toolchain but I think that is needlessly paranoid).

 > (Is there a way to run the binutils testuite on all targets all at once?)

Not really.  You can run the binutils testsuites with an all-targets 
toolchain but it will just check the toolchain's default target, not all 
of the targets it can possibly support.

>> This assumes that the contents of 'mode' are well defined.  Is this 
>> the case for non-POSIX environments ?  For example can we be sure that 
>> the character 'R' is never used to indicate read-only status, or that 
>> an OS might allow a file created with just "a" to have the 
>> newly-written-to parts read back, effectively making "a" a 
>> read-and-write mode ?  What I am getting at is, should bfd_fopen() 
>> take an explicit extra parameter which tells BFD whether this file is 
>> intended for reading, writing or both ?
> 
> 
> Hmm.  In practice, we always use one of the FOPEN_* macros as an 
> argument, and these do follow the rules implied by what I wrote.  But, I 
> could tighten the test to check for just what ISO C requires, which is 
> that the characters must occur at the start of the string, so using 
> strchr is probably incorrect.  OK to make that change before check-in, 
> or would you like me to resubmit?

No please just make the change before check-in.

> I'm not aware of OSes that do as you say, but, in any case, I don't 
> think we need to worry about OSes that accept other variations.  Clients 
> of BFD should be using the standard syntax.  It's OK if they use OS 
> extensions, but I think it's reasonable to say that if they mean "read" 
> they use "r" and not "R".

Fair enough.

Cheers
   Nick