basic: split ifname related calls from format-util.h into format-ifname.h

This way we don't have to pull in net/if.h into format-util.h.

This is supposed to address https://github.com/systemd/systemd/pull/32212#discussion_r1755639881

No actual code changes, just a .c/.h file split-up.

1 files changed, 37 insertions, 0 deletions

diff --git a/src/basic/format-ifname.c b/src/basic/format-ifname.c
new file mode 100644
index 0000000000..ce4933c57d
--- /dev/null
+++ b/src/basic/format-ifname.c
@@ -0,0 +1,37 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "format-ifname.h"
+#include "string-util.h"
+
+assert_cc(STRLEN("%") + DECIMAL_STR_MAX(int) <= IF_NAMESIZE);
+
+int format_ifname_full(int ifindex, FormatIfnameFlag flag, char buf[static IF_NAMESIZE]) {
+        if (ifindex <= 0)
+                return -EINVAL;
+
+        if (if_indextoname(ifindex, buf))
+                return 0;
+
+        if (!FLAGS_SET(flag, FORMAT_IFNAME_IFINDEX))
+                return -errno;
+
+        if (FLAGS_SET(flag, FORMAT_IFNAME_IFINDEX_WITH_PERCENT))
+                assert_se(snprintf_ok(buf, IF_NAMESIZE, "%%%d", ifindex));
+        else
+                assert_se(snprintf_ok(buf, IF_NAMESIZE, "%d", ifindex));
+
+        return 0;
+}
+
+int format_ifname_full_alloc(int ifindex, FormatIfnameFlag flag, char **ret) {
+        char buf[IF_NAMESIZE];
+        int r;
+
+        assert(ret);
+
+        r = format_ifname_full(ifindex, flag, buf);
+        if (r < 0)
+                return r;
+
+        return strdup_to(ret, buf);
+}