28 lines
662 B
C
28 lines
662 B
C
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#include <u.h>
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#include <libc.h>
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ulong
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truerand(void)
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{
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int i, n;
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uchar buf[sizeof(ulong)];
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ulong x;
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static int randfd = -1;
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static char *randfile;
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if(randfd < 0){
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randfd = open(randfile="/dev/random", OREAD);
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/* OpenBSD lets you open /dev/random but not read it! */
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if(randfd < 0 || read(randfd, buf, 1) != 1)
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randfd = open(randfile="/dev/srandom", OREAD); /* OpenBSD */
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if(randfd < 0)
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sysfatal("can't open %s: %r", randfile);
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fcntl(randfd, F_SETFD, FD_CLOEXEC);
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}
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for(i=0; i<sizeof(buf); i += n)
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if((n = readn(randfd, buf+i, sizeof(buf)-i)) < 0)
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sysfatal("can't read %s: %r", randfile);
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memmove(&x, buf, sizeof x);
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return x;
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}
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