mood.c: Avoid overflow in update_quadratic_deviation().

[paraslash.git] / mood.c

diff --git a/mood.c b/mood.c
index e905f92cc64b4e99d55691d3d9e5805e3f3985d1..45b051a7267cdd9cd1a9049a00685a150681a1cb 100644 (file)
--- a/mood.c
+++ b/mood.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2007-2012 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2007-2013 Andre Noll <maan@systemlinux.org>
  *
  * Licensed under the GPL v2. For licencing details see COPYING.
  */
@@ -77,6 +77,10 @@ struct mood {
        struct list_head score_list;
 };
 
+/*
+ * If current_mood is NULL then no mood is currently open. If
+ * current_mood->name is NULL, the dummy mood is currently open
+ */
 static struct mood *current_mood;
 
 /**
@@ -218,7 +222,8 @@ static void destroy_mood(struct mood *m)
 static struct mood *alloc_new_mood(const char *name)
 {
        struct mood *m = para_calloc(sizeof(struct mood));
-       m->name = para_strdup(name);
+       if (name)
+               m->name = para_strdup(name);
        INIT_LIST_HEAD(&m->accept_list);
        INIT_LIST_HEAD(&m->deny_list);
        INIT_LIST_HEAD(&m->score_list);
@@ -381,7 +386,7 @@ static int load_mood(const struct osl_row *mood_row, struct mood **m)
        if (!*mood_name)
                return -E_DUMMY_ROW;
        mlpd.m = alloc_new_mood(mood_name);
-       ret = for_each_line_ro(mood_def.data, mood_def.size,
+       ret = for_each_line(FELF_READ_ONLY, mood_def.data, mood_def.size,
                parse_mood_line, &mlpd);
        osl_close_disk_object(&mood_def);
        if (ret < 0) {
@@ -413,7 +418,7 @@ static int check_mood(struct osl_row *mood_row, void *data)
        ret = para_printf(pb, "checking mood %s...\n", mood_name);
        if (ret < 0)
                goto out;
-       ret = for_each_line_ro(mood_def.data, mood_def.size,
+       ret = for_each_line(FELF_READ_ONLY, mood_def.data, mood_def.size,
                parse_mood_line, &mlpd);
        if (ret < 0)
                para_printf(pb, "%s line %u: %s\n", mood_name, mlpd.line_num,
@@ -467,7 +472,7 @@ static int64_t normalized_value(int64_t x, int64_t n, int64_t sum, int64_t qd)
 {
        if (!n || !qd)
                return 0;
-       return 100 * (n * x - sum) / (int64_t)int_sqrt(n * qd);
+       return 100 * (n * x - sum) / (int64_t)int_sqrt(n) / (int64_t)int_sqrt(qd);
 }
 
 static long compute_num_played_score(struct afs_info *afsi)
@@ -499,7 +504,7 @@ static long compute_dynamic_score(const struct osl_row *aft_row)
 
 static int add_afs_statistics(const struct osl_row *row)
 {
-       uint64_t n, x, s;
+       uint64_t n, x, s, q;
        struct afs_info afsi;
        int ret;
 
@@ -509,14 +514,18 @@ static int add_afs_statistics(const struct osl_row *row)
        n = statistics.num;
        x = afsi.last_played;
        s = statistics.last_played_sum;
-       if (n > 0)
-               statistics.last_played_qd += (x - s / n) * (x - s / n) * n / (n + 1);
+       if (n > 0) {
+               q = (x > s / n)? x - s / n : s / n - x;
+               statistics.last_played_qd += q * q * n / (n + 1);
+       }
        statistics.last_played_sum += x;
 
        x = afsi.num_played;
        s = statistics.num_played_sum;
-       if (n > 0)
-               statistics.num_played_qd += (x - s / n) * (x - s / n) * n / (n + 1);
+       if (n > 0) {
+               q = (x > s / n)? x - s / n : s / n - x;
+               statistics.num_played_qd += q * q * n / (n + 1);
+       }
        statistics.num_played_sum += x;
        statistics.num++;
        return 1;
@@ -643,7 +652,8 @@ static int add_if_admissible(struct osl_row *aft_row, void *data)
  * the last number a_n was replaced by b) may be computed in O(1) time in terms
  * of n, q, a_n, b, and S as
  *
- *     q' = q + d * s - (2 * S + d) * d / n,
+ *     q' = q + d * s - (2 * S + d) * d / n
+ *        = q + d * (s - 2 * S / n - d /n),
  *
  * where d = b - a_n, and s = b + a_n.
  *
@@ -660,7 +670,7 @@ _static_inline_ int64_t update_quadratic_deviation(int64_t n, int64_t old_qd,
 {
        int64_t delta = new_val - old_val;
        int64_t sigma = new_val + old_val;
-       return old_qd + delta * sigma - (2 * old_sum + delta) * delta / n;
+       return old_qd + delta * (sigma - 2 * old_sum / n - delta / n);
 }
 
 static int update_afs_statistics(struct afs_info *old_afsi, struct afs_info *new_afsi)
@@ -850,9 +860,9 @@ int change_current_mood(char *mood_name)
                        return ret;
                close_current_mood();
                current_mood = m;
-       } else {
+       } else { /* load dummy mood */
                close_current_mood();
-               current_mood = alloc_new_mood("dummy");
+               current_mood = alloc_new_mood(NULL);
        }
        aa.m = current_mood;
        PARA_NOTICE_LOG("computing statistics of admissible files\n");
@@ -867,7 +877,7 @@ int change_current_mood(char *mood_name)
                if (ret < 0)
                        goto out;
        }
-       PARA_NOTICE_LOG("loaded mood %s\n", current_mood->name);
+       PARA_NOTICE_LOG("loaded mood %s\n", mood_name? mood_name : "(dummy)");
        ret = statistics.num;
 out:
        free(aa.array);
@@ -891,6 +901,9 @@ static int reload_current_mood(void)
        int ret;
        char *mood_name = NULL;
 
+       ret = clear_score_table();
+       if (ret < 0)
+               return ret;
        if (!current_mood)
                return 1;
        PARA_NOTICE_LOG("reloading %s\n", current_mood->name?
@@ -913,12 +926,12 @@ static int reload_current_mood(void)
  * This function performs actions required due to the occurrence of the given
  * event. Possible actions include reload of the current mood and update of the
  * score of an audio file.
+ *
+ * \return Standard.
  */
 int moods_event_handler(enum afs_events event, __a_unused struct para_buffer *pb,
                void *data)
 {
-       int ret;
-
        if (!current_mood)
                return 0;
        switch (event) {
@@ -931,10 +944,6 @@ int moods_event_handler(enum afs_events event, __a_unused struct para_buffer *pb
        case BLOB_ADD:
                if (data == moods_table || data == playlists_table)
                        return 1; /* no reload necessary for these */
-               ret = clear_score_table();
-               if (ret < 0)
-                       PARA_CRIT_LOG("clear score table returned %s\n",
-                               para_strerror(-ret));
                return reload_current_mood();
        /* these also require reload of the score table */
        case ATTRIBUTE_ADD: