Re: [boost] [filesystem] How to remove specific files from a directory?

Subject: Re: [boost] [filesystem] How to remove specific files from a directory?
From: Mateusz Loskot (mateusz_at_[hidden])
Date: 2016-09-07 10:07:20

On 7 September 2016 at 15:46, Andrey Semashev <andrey.semashev_at_[hidden]> wrote:
> On 09/07/16 16:06, Andrzej Krzemienski wrote:
>>
>> Hi,
>> I wonder what is boost::filesystem recommendation for solving the
>> following
>> problem.
>>
>> I want to remove all files from a given directory that satisfy a certain
>> predicate, e.g., only these whose names start with letter "s".
>>
>> It is my understanding that the calling filesystem::remove may invalidate
>> the iterator, and therefore the following solution is incorrect:
>>
>> fsys::directory_iterator it{path}, itEnd{};
>> for ( ; it != itEnd ; ++it )
>> {
>>   if (predicate(*it))
>>     fsys::remove(it->path());
>> }
>>
>> But, is the following guaranteed to work?:
>>
>> fsys::directory_iterator it{path}, itEnd{};
>> for ( ; it != itEnd ; )
>> {
>>   if (predicate(*it))
>>     fsys::remove((it++)->path());
>>   else
>>     ++it;
>> }
>
>
> From the documentation, it seems the behavior should be similar to readdir,
> in which case it would seem that both pieces of code above are valid.

Indeed, boost::filesystem and std::filesystem (ISO/IEC TS 18822:2015) as well
as POSIX readdir behave in the same way.
But, for all of them, behaviour is unspecified in case content of
directory that is
being traversed changes.

Best regards,
-- 
Mateusz Loskot, http://mateusz.loskot.net