Re: [Bug-wget] flock is not available on solaris 10 (at least sparc)

[Tim Ruehsen]

On Wednesday 16 December 2015 10:31:33 Giuseppe Scrivano wrote:
> Tim Ruehsen <address@hidden> writes:
> > On Tuesday 15 December 2015 21:55:53 Kiyoshi KANAZAWA wrote:
> >> 2. about #error "Compiler or options invalid for pre-UNIX 03 X/Open
> >> applications" This error may depends on compilers.
> >> Both of  "solarisstudio12.4"  &  "gcc-4.8.5" can build wget-1.17.1
> >> without
> >> errors.
> >> 
> >> But I once experienced the similar problem when trying to compile
> >> "sam2p-0.49.2". At that time, gcc-4.4.7 passed, but gcc-4.8.* stopped
> >> with
> >> this error and I had to set "-D_XPG6" as optional cc flags.
> >> 
> >> ./configure of wget checks compiler to accept ISO C89, such as
> >> "checking for gcc -O3 option to accept ISO C89... none needed".
> >> If "-std=c89" is required for some versions of gcc, shouldn't it set in
> >> configure ?
> > 
> > You could try to insert AC_PROG_CC_C89 after AC_PROG_CC. AFAIK, it will
> > add - std=c89 but only if needed (if the compiler does not support C89
> > without it).
> > 
> > autoreconf && ./configure && make clean && make
> > to see if the problem still occurs.
> > 
> > Setting CFLAGS directly in configure.ac is not recommended, AFAIK. Maybe
> > just a set of compilers understands -std=c89 !? Also, setting -std=c89
> > might be helpful or not, depending of the compiler and version. Nobody is
> > going to waste time working on such a list/table.
> > 
> > Maybe we should ask the gnulib people, why flock() isn't emulated on
> > Solaris when -std=c89 is missing !? I could simply be a bug...
> 
> the gnulib documentation for flock says:
> 
>   Portability problems not fixed by Gnulib:
> 
>     This function is missing on some platforms:
>     AIX 5.1, HP-UX 11.23, Solaris 11 2011-11, BeOS.
> 
> This can either be because nobody cared before, or because there is no
> way to emulate it on these platforms.
> 
> Couldn't we replace the flock part with a write to a tmp file+atomic
> rename?  In the remote case of two wget processes trying to write the
> same file, at least we won't get garbage there.  What do you think?

There is no atomic rename for all OSes, AFAIK.

How about using fcntl() for locking ? The gnulib emulation might be better and 
it is a POSIX function.

Tim

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