Prevent to divide by zero and range out of 0..1

diff --git a/contrib/tsearch2/rank.c b/contrib/tsearch2/rank.c
index a58986e474118fd8f04936a0afd00b923aa12ed2..046b062b97d7ea45e6369fbea0f03003cc6dfddc 100644 (file)
--- a/contrib/tsearch2/rank.c
+++ b/contrib/tsearch2/rank.c
@@ -288,6 +288,7 @@ calc_rank(float *w, tsvector * t, QUERYTYPE * q, int4 method)
 {
    ITEM       *item = GETQUERY(q);
    float       res = 0.0;
+   int        len;
 
    if (!t->size || !q->size)
        return 0.0;
@@ -303,10 +304,11 @@ calc_rank(float *w, tsvector * t, QUERYTYPE * q, int4 method)
        case 0:
            break;
        case 1:
-           res /= log((float) cnt_length(t));
+           res /= log( (float)(cnt_length(t)+1) ) / log(2.0);
            break;
        case 2:
-           res /= (float) cnt_length(t);
+           len = cnt_length(t);
+           if ( len > 0 )  res /= (float)len; 
            break;
        default:
            /* internal error */
@@ -609,10 +611,11 @@ rank_cd(PG_FUNCTION_ARGS)
        case 0:
            break;
        case 1:
-           res /= log((float) cnt_length(txt));
+           res /= log( (float)(cnt_length(txt)+1) );
            break;
        case 2:
-           res /= (float) cnt_length(txt);
+           len = cnt_length(txt);
+           if ( len > 0 )  res /= (float)len; 
            break;
        default:
            /* internal error */