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

[Giuseppe Scrivano]

Tim Ruehsen <address@hidden> writes:

> 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.

it will break on mingw :(

fcntl:

  Portability problems not fixed by Gnulib:
    The replacement function does not support F_SETFD,
      F_GETFL, F_SETFL, F_GETOWN, F_SETOWN,
      F_GETLK, F_SETLK, and F_SETLKW on some platforms:
      mingw, MSVC 9.

but we can perhaps use this when flock is not available.

Regards,
Giuseppe