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Date: Wed, 24 Aug 2016 10:19:16 +0300
From: Alexey Dobriyan <adobriyan@gmail.com>
Subject: Re: [PATCH] fixdep: faster CONFIG_ search
Message-ID: <20160824071916.GA1844@p183.telecom.by>
References: <20160823184724.GA11707@p183.telecom.by>
 <20160824050108.GA19050@ravnborg.org>
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To: Sam Ravnborg <sam@ravnborg.org>
Cc: mmarek@suse.com, akpm@linux-foundation.org, linux-kbuild@vger.kernel.org

On Wed, Aug 24, 2016 at 07:01:08AM +0200, Sam Ravnborg wrote:
> > -	map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
> > -	if ((long) map == -1) {
> > -		perror("fixdep: mmap");
> > +	map = malloc(st.st_size + 1);
> > +	if (!map) {
> > +		perror("fixdep: malloc");
> >  		close(fd);
> >  		return;
> >  	}
> > +	if (read(fd, map, st.st_size) != st.st_size) {
> > +		perror("fixdep: read");
> > +		close(fd);
> > +		return;
> > +	}
> > +	map[st.st_size] = '\0';
> > +	close(fd);
> >  
> > -	parse_config_file(map, st.st_size);
> > -
> > -	munmap(map, st.st_size);
> > +	parse_config_file(map);
> >  
> > -	close(fd);
> > +	free(map);
> >  }
> This change is not described in the changelog..
> What is the rationale?

There is no raw memory equivalent of strstr(), so a file is made into
a string.