+static int should_lookahead(struct grep_opt *opt)
+{
+ struct grep_pat *p;
+
+ if (opt->extended)
+ return 0; /* punt for too complex stuff */
+ if (opt->invert)
+ return 0;
+ for (p = opt->pattern_list; p; p = p->next) {
+ if (p->token != GREP_PATTERN)
+ return 0; /* punt for "header only" and stuff */
+ }
+ return 1;
+}
+
+static int look_ahead(struct grep_opt *opt,
+ unsigned long *left_p,
+ unsigned *lno_p,
+ char **bol_p)
+{
+ unsigned lno = *lno_p;
+ char *bol = *bol_p;
+ struct grep_pat *p;
+ char *sp, *last_bol;
+ regoff_t earliest = -1;
+
+ for (p = opt->pattern_list; p; p = p->next) {
+ int hit;
+ regmatch_t m;
+
+ if (p->fixed)
+ hit = !fixmatch(p->pattern, bol, p->ignore_case, &m);
+ else {
+#ifdef REG_STARTEND
+ m.rm_so = 0;
+ m.rm_eo = *left_p;
+ hit = !regexec(&p->regexp, bol, 1, &m, REG_STARTEND);
+#else
+ hit = !regexec(&p->regexp, bol, 1, &m, 0);
+#endif
+ }
+ if (!hit || m.rm_so < 0 || m.rm_eo < 0)
+ continue;
+ if (earliest < 0 || m.rm_so < earliest)
+ earliest = m.rm_so;
+ }
+
+ if (earliest < 0) {
+ *bol_p = bol + *left_p;
+ *left_p = 0;
+ return 1;
+ }
+ for (sp = bol + earliest; bol < sp && sp[-1] != '\n'; sp--)
+ ; /* find the beginning of the line */
+ last_bol = sp;
+
+ for (sp = bol; sp < last_bol; sp++) {
+ if (*sp == '\n')
+ lno++;
+ }
+ *left_p -= last_bol - bol;
+ *bol_p = last_bol;
+ *lno_p = lno;
+ return 0;
+}
+
+int grep_threads_ok(const struct grep_opt *opt)
+{
+ /* If this condition is true, then we may use the attribute
+ * machinery in grep_buffer_1. The attribute code is not
+ * thread safe, so we disable the use of threads.
+ */
+ if (opt->funcname && !opt->unmatch_name_only && !opt->status_only &&
+ !opt->name_only)
+ return 0;
+
+ /* If we are showing hunk marks, we should not do it for the
+ * first match. The synchronization problem we get for this
+ * constraint is not yet solved, so we disable threading in
+ * this case.
+ */
+ if (opt->pre_context || opt->post_context)
+ return 0;
+
+ return 1;
+}
+
+static void std_output(struct grep_opt *opt, const void *buf, size_t size)
+{
+ fwrite(buf, size, 1, stdout);
+}
+