From add83539899242bf8ddbbac28fe2fde17c4c0bce Mon Sep 17 00:00:00 2001
From: Oneric <oneric@oneric.stub>
Date: Mon, 12 Oct 2020 22:47:03 +0200
Subject: Allocate and set default style directly at track creation

This way we can ensure that there's always one style in the track (which
some parts of the code already assume) and that this style is actually
valid.
If the style alloc fails, the whole track alloc will fail and we're
likely seriously short on memory anyway
---
 libass/ass.c | 41 ++++++++++++++++++++---------------------
 1 file changed, 20 insertions(+), 21 deletions(-)

(limited to 'libass')

diff --git a/libass/ass.c b/libass/ass.c
index 87edd90..b64b070 100644
--- a/libass/ass.c
+++ b/libass/ass.c
@@ -334,14 +334,6 @@ static int process_event_tail(ASS_Track *track, ASS_Event *event,
     char *format = strdup(track->event_format);
     char *q = format;           // format scanning pointer
 
-    if (track->n_styles == 0) {
-        // add "Default" style to the end
-        // will be used if track does not contain a default style (or even does not contain styles at all)
-        int sid = ass_alloc_style(track);
-        set_default_style(&track->styles[sid]);
-        track->default_style = sid;
-    }
-
     for (i = 0; i < n_ignored; ++i) {
         NEXT(q, tname);
     }
@@ -492,14 +484,6 @@ static int process_style(ASS_Track *track, char *str)
 
     q = format = strdup(track->style_format);
 
-    // Add default style first
-    if (track->n_styles == 0) {
-        // will be used if track does not contain a default style (or even does not contain styles at all)
-        int sid = ass_alloc_style(track);
-        set_default_style(&track->styles[sid]);
-        track->default_style = sid;
-    }
-
     ass_msg(track->library, MSGL_V, "[%p] Style: %s", track, str);
 
     sid = ass_alloc_style(track);
@@ -1478,18 +1462,33 @@ long long ass_step_sub(ASS_Track *track, long long now, int movement)
 
 ASS_Track *ass_new_track(ASS_Library *library)
 {
+    int def_sid = -1;
     ASS_Track *track = calloc(1, sizeof(ASS_Track));
     if (!track)
-        return NULL;
+        goto fail;
     track->library = library;
     track->ScaledBorderAndShadow = 0;
     track->parser_priv = calloc(1, sizeof(ASS_ParserPriv));
-    if (!track->parser_priv) {
-        free(track);
-        return NULL;
-    }
+    if (!track->parser_priv)
+        goto fail;
+    def_sid = ass_alloc_style(track);
+    if (def_sid < 0)
+        goto fail;
+    set_default_style(track->styles + def_sid);
+    track->default_style = def_sid;
+    if (!track->styles[def_sid].Name || !track->styles[def_sid].FontName)
+        goto fail;
     track->parser_priv->check_readorder = 1;
     return track;
+
+fail:
+    if (track) {
+        if (def_sid >= 0)
+            ass_free_style(track, def_sid);
+        free(track->parser_priv);
+        free(track);
+    }
+    return NULL;
 }
 
 int ass_track_set_feature(ASS_Track *track, ASS_Feature feature, int enable)
-- 
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