1 files changed, 78 insertions, 0 deletions
diff --git a/src/master/dup2-array.c b/src/master/dup2-array.c
new file mode 100644
index 0000000..062590a
--- /dev/null
+++ b/src/master/dup2-array.c
@@ -0,0 +1,78 @@
+/* Copyright (c) 2007-2018 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+#include "array.h"
+#include "dup2-array.h"
+
+#include <unistd.h>
+
+void dup2_append(ARRAY_TYPE(dup2) *dups, int fd_src, int fd_dest)
+{
+	struct dup2 d;
+
+	i_assert(fd_src >= 0);
+	i_assert(fd_dest >= 0);
+
+	d.fd_src = fd_src;
+	d.fd_dest = fd_dest;
+	array_push_back(dups, &d);
+}
+
+int dup2_array(ARRAY_TYPE(dup2) *dups_arr)
+{
+	struct dup2 *dups;
+	bool *moved, moves;
+	unsigned int i, j, count, conflict;
+	int fd;
+
+	dups = array_get_modifiable(dups_arr, &count);
+
+	moved = t_new(bool, count);
+	for (;;) {
+		conflict = count;
+		moves = FALSE;
+		for (i = 0; i < count; i++) {
+			if (moved[i])
+				continue;
+
+			for (j = 0; j < count; j++) {
+				if (dups[j].fd_src == dups[i].fd_dest &&
+				    !moved[j]) {
+					conflict = j;
+					break;
+				}
+			}
+
+			if (j == count) {
+				/* no conflicts, move it */
+				moved[i] = TRUE;
+				moves = TRUE;
+				if (dup2(dups[i].fd_src, dups[i].fd_dest) < 0) {
+					i_error("dup2(%d, %d) failed: %m",
+						dups[i].fd_src,
+						dups[i].fd_dest);
+					return -1;
+				}
+			}
+		}
+		if (conflict == count)
+			break;
+
+		if (moves) {
+			/* it's possible that the conflicting fd was
+			   moved already. try again. */
+			continue;
+		}
+
+		/* ok, we have to dup() */
+		fd = dup(dups[conflict].fd_src);
+		if (fd == -1) {
+			i_error("dup(%d) failed: %m", dups[conflict].fd_src);
+			return -1;
+		}
+		fd_close_on_exec(fd, TRUE);
+                dups[conflict].fd_src = fd;
+	}
+	return 0;
+}
+