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1) Fix longstanding math bug with denominator > 1 (wrong probability).

Browse Source 
Test case:
	random -f some_small_file 10000
(in most cases must be no output)
2) Prevent number of lines > RANDOM_MAX (overflow or nothing may be
choosed) with EFBIG err()
3) After line is found, terminate list loop for -U case too,
since nothing to do in the rest of the loop left.
This commit is contained in:
Andrey A. Chernov 2008-08-08 02:46:47 +00:00
parent 67cc8dbb1a
commit 2c38883d2a
1 changed files with 16 additions and 8 deletions
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24
games/random/randomize_fd.c
View File

@ -32,6 +32,7 @@ __FBSDID("$FreeBSD$");
#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
@ -94,10 +95,11 @@ int
randomize_fd(int fd, int type, int unique, double denom)
{
u_char *buf;
u_int numnode, j, selected, slen;
u_int slen;
u_long i, j, numnode, selected;
struct rand_node *n, *prev;
int bufleft, eof, fndstr, ret;
size_t bufc, buflen, i;
size_t bufc, buflen;
ssize_t len;
rand_root = rand_tail = NULL;
@ -173,6 +175,11 @@ randomize_fd(int fd, int type, int unique, double denom)
(type == RANDOM_TYPE_WORDS && isspace(buf[i])) ||
(eof && i == buflen - 1)) {
make_token:
if (numnode == RANDOM_MAX) {
errno = EFBIG;
err(1, "too many lines");
}
numnode++;
n = rand_node_allocate();
if (-1 != (int)i) {
slen = i - (u_long)bufc;
@ -188,7 +195,6 @@ randomize_fd(int fd, int type, int unique, double denom)
}
rand_node_append(n);
fndstr = 1;
numnode++;
}
}
}
@ -202,16 +208,18 @@ randomize_fd(int fd, int type, int unique, double denom)
}
for (i = numnode; i > 0; i--) {
selected = ((int)denom * random())/(RANDOM_MAX / numnode);
selected = random() % numnode;
for (j = 0, prev = n = rand_root; n != NULL; j++, prev = n, n = n->next) {
if (j == selected) {
if (n->cp == NULL)
break;
ret = printf("%.*s", (int)n->len - 1, n->cp);
if (ret < 0)
err(1, "printf");
if ((int)(denom * random() / RANDOM_MAX) == 0) {
ret = printf("%.*s", (int)n->len - 1, n->cp);
if (ret < 0)
err(1, "printf");
}
if (unique) {
if (n == rand_root)
rand_root = n->next;
@ -221,8 +229,8 @@ randomize_fd(int fd, int type, int unique, double denom)
prev->next = n->next;
rand_node_free(n);
numnode--;
break;
}
break;
}
}
}