From:	gpk AT physics DOT att DOT com
Date:	Tue, 2 Feb 93 08:44:03 EST
Original-From:	physics!gpk (Greg Kochanski)
To:	djgpp AT sun DOT soe DOT clarkson DOT edu
Subject:	Gcc 2.3.3

>I was thinking about a solution to use gcc 2.3.3 on a 8.3 dos file
>system.
>The idea is to intercept the "creat" and "open" calls either in the
>library or in go32 so that they generate unique file names for the
>TMPDIR.

It's a nice solution.  You'd just use those open, creat (and unlink,
and stat(), and access()) in Gcc itself, and fall back to the normal
versions in the library.

>There will be need to keep a corespondance table between the
>long file names and the generated ones

Too much work.  Just write a good hash function from an arbitrary string
into an 8+3 filename.  There are about 10^16 possible 8+3 filenames,
so the odds of getting a duplicate are pretty small.

Something like (and this is just a sketch):

const char fnset[] = "abcdefghijklmnopqrstuvwxyz0123456789-_+";
#define NC (sizeof(fnset)-1)
#define BIGPRIME	something_big_that_fits_in_an_int

void makedosname(const char *s, char name[13])
{
 const static int mult[11] = {1, 2, 3, 5, 7, 11, 13, 17, 19, 23, 29};
 int i;
 char *p;
 for(i=0;i<11;i++)	{
	int accum = 0;
	for(p=s;*p;p++)
		accum = (accum*mult[i] + ((unsigned)(*p)&0377))%BIGPRIME;
	name[i>=8 ? i+1 : i] = fnset[accum%NC];
	}
 name[8] = ".";
 name[12] = '\0';
}

So, every input string will be mapped into a filename, and the mapping
will be the same every time (depending only on NC, BIGPRIME, and mult[i]).
The names will be totally garbled, but it doesn't matter for temp. files.


Greg Kochanski   gpk AT physics DOT att DOT com
AT&T Physics Research -- Physics for Fun and Profit

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