+/**************************************************************/
+/* Pretrigger handling for debug. The debug_printf implementation
+diverts output to a circular buffer if the buffer is set up.
+The routines here set up the buffer, and unload it to file (and release it).
+What ends up in the buffer is subject to the usual debug_selector. */
+
+void
+debug_pretrigger_setup(const uschar * size_string)
+{
+long size = Ustrtol(size_string, NULL, 0);
+if (size > 0)
+ {
+ unsigned bufsize = MIN(size, 16384);
+
+ dtrigger_selector |= BIT(DTi_pretrigger);
+ if (debug_pretrigger_buf) store_free(debug_pretrigger_buf);
+ debug_pretrigger_buf = store_malloc((size_t)(debug_pretrigger_bsize = bufsize));
+ pretrigger_readoff = pretrigger_writeoff = 0;
+ }
+}
+
+void
+debug_trigger_fire(void)
+{
+int nbytes;
+
+if (!debug_pretrigger_buf) return;
+
+if (debug_file && (nbytes = pretrigger_writeoff - pretrigger_readoff) != 0)
+ if (nbytes > 0)
+ fwrite(debug_pretrigger_buf + pretrigger_readoff, 1, nbytes, debug_file);
+ else
+ {
+ fwrite(debug_pretrigger_buf + pretrigger_readoff, 1,
+ debug_pretrigger_bsize - pretrigger_readoff, debug_file);
+ fwrite(debug_pretrigger_buf, 1, pretrigger_writeoff, debug_file);
+ }
+
+debug_pretrigger_discard();
+}
+
+void
+debug_pretrigger_discard(void)
+{
+if (debug_pretrigger_buf) store_free(debug_pretrigger_buf);
+debug_pretrigger_buf = NULL;
+dtrigger_selector = 0;
+}
+
+