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https://github.com/tytso/pwgen.git
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1459a31e07
Get rid of 2 left-overs from commit ccda6f21 and in addition remove a misleading comment.
Signed-off-by: Toralf Förster <toralf.foerster@gmx.de>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
71 lines
1.3 KiB
C
71 lines
1.3 KiB
C
/*
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* randnum.c -- generate (good) randum numbers.
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*
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* Copyright (C) 2001,2002 by Theodore Ts'o
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*
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* This file may be distributed under the terms of the GNU Public
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* License.
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*/
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#include <stdio.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <sys/types.h>
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#include <sys/time.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <errno.h>
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#include "pwgen.h"
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static int get_random_fd(void);
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static int get_random_fd()
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{
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static int fd = -2;
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if (fd == -2) {
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fd = open("/dev/urandom", O_RDONLY);
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if (fd == -1)
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fd = open("/dev/random", O_RDONLY | O_NONBLOCK);
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}
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return fd;
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}
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/*
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* Generate a random number n, where 0 <= n < max_num, using
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* /dev/urandom if possible.
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*/
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int pw_random_number(max_num)
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int max_num;
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{
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unsigned int rand_num;
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int i, fd = get_random_fd();
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int lose_counter = 0, nbytes = sizeof(rand_num);
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char *cp = (char *) &rand_num;
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if (fd >= 0) {
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while (nbytes > 0) {
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i = read(fd, cp, nbytes);
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if ((i < 0) &&
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((errno == EINTR) || (errno == EAGAIN)))
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continue;
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if (i <= 0) {
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if (lose_counter++ == 8)
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break;
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continue;
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}
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nbytes -= i;
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cp += i;
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lose_counter = 0;
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}
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}
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if (nbytes == 0)
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return (rand_num % max_num);
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/* We weren't able to use /dev/random, fail hard */
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fprintf(stderr, "No entropy available!\n");
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exit(1);
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}
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