1 files changed, 105 insertions, 0 deletions
diff --git a/sub/filter_regex.c b/sub/filter_regex.c
new file mode 100644
index 0000000000..a5aa03a849
--- /dev/null
+++ b/sub/filter_regex.c
@@ -0,0 +1,105 @@
+#include <regex.h>
+#include <sys/types.h>
+
+#include "common/common.h"
+#include "common/msg.h"
+#include "misc/bstr.h"
+#include "options/options.h"
+#include "sd.h"
+
+struct priv {
+    int offset;
+    regex_t *regexes;
+    int num_regexes;
+};
+
+static bool rf_init(struct sd_filter *ft)
+{
+    if (strcmp(ft->codec, "ass") != 0)
+        return false;
+
+    if (!ft->opts->rf_enable)
+        return false;
+
+    struct priv *p = talloc_zero(ft, struct priv);
+    ft->priv = p;
+
+    for (int n = 0; ft->opts->rf_items && ft->opts->rf_items[n]; n++) {
+        char *item = ft->opts->rf_items[n];
+
+        MP_TARRAY_GROW(p, p->regexes, p->num_regexes);
+        regex_t *preg = &p->regexes[p->num_regexes];
+
+        int err = regcomp(preg, item, REG_ICASE | REG_EXTENDED | REG_NOSUB);
+        if (err) {
+            char errbuf[512];
+            regerror(err, preg, errbuf, sizeof(errbuf));
+            MP_ERR(ft, "Regular expression error: '%s'\n", errbuf);
+            continue;
+        }
+
+        p->num_regexes += 1;
+    }
+
+    if (!p->num_regexes)
+        return false;
+
+    char *headers = ft->event_format;
+    while (headers && headers[0]) {
+        p->offset += 1;
+        headers = strchr(headers, ',');
+        if (headers)
+            headers += 1;
+    }
+    p->offset -= 1; // removes Start/End, adds ReadOrder
+
+    return true;
+}
+
+static void rf_uninit(struct sd_filter *ft)
+{
+    struct priv *p = ft->priv;
+
+    for (int n = 0; n < p->num_regexes; n++)
+        regfree(&p->regexes[n]);
+}
+
+static struct demux_packet *rf_filter(struct sd_filter *ft,
+                                      struct demux_packet *pkt)
+{
+    struct priv *p = ft->priv;
+    char *line = bstrto0(NULL, (bstr){(char *)pkt->buffer, pkt->len});
+    bool drop = false;
+
+    char *text = line;
+    for (int n = 0; n < p->offset - 1; n++) {
+        text = strchr(text, ',');
+        if (!text) {
+            MP_WARN(ft, "Malformed event: '%s'\n", line);
+            text = line; // shouldn't happen; random fallback
+            break;
+        }
+        text = text + 1;
+    }
+
+    for (int n = 0; n < p->num_regexes; n++) {
+        int err = regexec(&p->regexes[n], text, 0, NULL, 0);
+        if (err == 0) {
+            int level = ft->opts->rf_warn ? MSGL_WARN : MSGL_V;
+            MP_MSG(ft, level, "Matching regex %d => drop: '%s'\n", n, text);
+            drop = true;
+            break;
+        } else if (err != REG_NOMATCH) {
+            MP_WARN(ft, "Error on regexec() on regex %d.\n", n);
+        }
+    }
+
+    talloc_free(line);
+    return drop ? NULL : pkt;
+}
+
+const struct sd_filter_functions sd_filter_regex = {
+    .init   = rf_init,
+    .uninit = rf_uninit,
+    .filter = rf_filter,
+};