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WebSVN – planix.SVN – Blame – /os/branches/feature-vt/sys/src/cmd/unix/u9fs/random.c – Rev 2

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#include <plan9.h>
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#include <fcall.h>
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#include <u9fs.h>
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#include <stdlib.h>
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#include <sys/time.h>
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#include <fcntl.h>
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static long
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getseed(void)
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{
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	struct timeval tv;
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	long seed;
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	int fd, len;
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	len = 0;
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	fd = open("/dev/urandom", O_RDONLY);
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	if(fd > 0){
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		len = readn(fd, &seed, sizeof(seed));
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		close(fd);
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	}
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	if(len != sizeof(seed)){
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		gettimeofday(&tv, nil);
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		seed = tv.tv_sec ^ tv.tv_usec ^ (getpid()<<8);
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	}
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	return seed;
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}
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static int seeded;
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void
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randombytes(uchar *r, uint nr)
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{
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	int i;
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	ulong l;
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	if(!seeded){
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		seeded=1;
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		srandom(getseed());
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	}
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	for(i=0; i+4<=nr; i+=4,r+=4){
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		l = (ulong)random();
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		r[0] = l;
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		r[1] = l>>8;
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		r[2] = l>>16;
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		r[3] = l>>24;
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	}
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	if(i<nr){
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		l = (ulong)random();
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		switch(nr-i){
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		case 3:
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			r[2] = l>>16;
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		case 2:
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			r[1] = l>>8;
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		case 1:
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			r[0] = l;
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		}
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	}
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}