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From: "Krzysztof Duleba" <krzysan AT skrzynka DOT pl>
Subject:  Re: cygwin setup 2.510.2.1 does not work because of an invalid iterator.
Date:  Sun, 11 Sep 2005 14:08:48 +0200
Lines: 39
Message-ID: <dg16o0$n7d$1@sea.gmane.org>
References:  <20050910 DOT 112834 DOT 57973656 DOT boochang AT m4 DOT kcn DOT ne DOT jp>
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This was originally sent to gmane.os.cygwin.applications, but I can't
write there.

M.Fujii wrote:
>
> Calling erase() in packagemata::ScanDownloadedFiles() invalidates
> iterator i.
> Therefore, ++i after erase() means an operation to a invalid
> iterator. I guess it is the cause of a crash of setup.exe.
>
> -      for (set<packageversion>::iterator i = pkg.versions.begin ();
> -    i != pkg.versions.end (); ++i)
> +      set<packageversion>::iterator i = pkg.versions.begin ();
> +      while (i != pkg.versions.end ())

> -          pkg.versions.erase(i);
> +          pkg.versions.erase(i++);

What's the difference? I mean, you're still using i after erasing it.
Shouldn't it be something along the lines of

{
    /* Should we erase */
    pkg.versions::iterator next_i = i;
    ++next_i;
    if(next_i == pkg.versions.end()){
        pkg.versions.erase(i);
        break;
    }else{
        pkg::value_type tmp = *next_i;
        pkg.versions.erase(i);
        i = pkg.versions.find(tmp);
    }
}else ++i;


Regards
Krzysztof Duleba



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