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

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.

1 files changed, 16 insertions, 8 deletions

diff --git a/games/random/randomize_fd.c b/games/random/randomize_fd.c
index e1011fb..c625d14 100644
--- a/games/random/randomize_fd.c
+++ b/games/random/randomize_fd.c
@@ -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;
 			}
 		}
 	}