basic,shared: move a bunch of files to src/shared/

The goal is to move everything that requires selinux or smack
away from src/basic/. This means that src/basic/label.[ch] must move,
which implies btrfs-util.[ch], copy.[ch], and a bunch of other files
which form a cluster of internal use.

This is just moving text around, so there should be no functional difference.

test-blockdev-util is new, because path_is_encrypted() is moved to
blockdev-util.c, and so far we didn't have any tests for code there.

src/shared/socket-label.c

@@ -0,0 +1,133 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <netinet/in.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <string.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+#include "alloc-util.h"
+#include "fd-util.h"
+#include "fs-util.h"
+#include "log.h"
+#include "macro.h"
+#include "missing_socket.h"
+#include "mkdir.h"
+#include "selinux-util.h"
+#include "socket-util.h"
+#include "umask-util.h"
+
+int socket_address_listen(
+                const SocketAddress *a,
+                int flags,
+                int backlog,
+                SocketAddressBindIPv6Only only,
+                const char *bind_to_device,
+                bool reuse_port,
+                bool free_bind,
+                bool transparent,
+                mode_t directory_mode,
+                mode_t socket_mode,
+                const char *label) {
+
+        _cleanup_close_ int fd = -1;
+        const char *p;
+        int r;
+
+        assert(a);
+
+        r = socket_address_verify(a, true);
+        if (r < 0)
+                return r;
+
+        if (socket_address_family(a) == AF_INET6 && !socket_ipv6_is_supported())
+                return -EAFNOSUPPORT;
+
+        if (label) {
+                r = mac_selinux_create_socket_prepare(label);
+                if (r < 0)
+                        return r;
+        }
+
+        fd = socket(socket_address_family(a), a->type | flags, a->protocol);
+        r = fd < 0 ? -errno : 0;
+
+        if (label)
+                mac_selinux_create_socket_clear();
+
+        if (r < 0)
+                return r;
+
+        if (socket_address_family(a) == AF_INET6 && only != SOCKET_ADDRESS_DEFAULT) {
+                r = setsockopt_int(fd, IPPROTO_IPV6, IPV6_V6ONLY, only == SOCKET_ADDRESS_IPV6_ONLY);
+                if (r < 0)
+                        return r;
+        }
+
+        if (IN_SET(socket_address_family(a), AF_INET, AF_INET6)) {
+                if (bind_to_device) {
+                        r = socket_bind_to_ifname(fd, bind_to_device);
+                        if (r < 0)
+                                return r;
+                }
+
+                if (reuse_port) {
+                        r = setsockopt_int(fd, SOL_SOCKET, SO_REUSEPORT, true);
+                        if (r < 0)
+                                log_warning_errno(r, "SO_REUSEPORT failed: %m");
+                }
+
+                if (free_bind) {
+                        r = socket_set_freebind(fd, socket_address_family(a), true);
+                        if (r < 0)
+                                log_warning_errno(r, "IP_FREEBIND/IPV6_FREEBIND failed: %m");
+                }
+
+                if (transparent) {
+                        r = socket_set_transparent(fd, socket_address_family(a), true);
+                        if (r < 0)
+                                log_warning_errno(r, "IP_TRANSPARENT/IPV6_TRANSPARENT failed: %m");
+                }
+        }
+
+        r = setsockopt_int(fd, SOL_SOCKET, SO_REUSEADDR, true);
+        if (r < 0)
+                return r;
+
+        p = socket_address_get_path(a);
+        if (p) {
+                /* Create parents */
+                (void) mkdir_parents_label(p, directory_mode);
+
+                /* Enforce the right access mode for the socket */
+                RUN_WITH_UMASK(~socket_mode) {
+                        r = mac_selinux_bind(fd, &a->sockaddr.sa, a->size);
+                        if (r == -EADDRINUSE) {
+                                /* Unlink and try again */
+
+                                if (unlink(p) < 0)
+                                        return r; /* didn't work, return original error */
+
+                                r = mac_selinux_bind(fd, &a->sockaddr.sa, a->size);
+                        }
+                        if (r < 0)
+                                return r;
+                }
+        } else {
+                if (bind(fd, &a->sockaddr.sa, a->size) < 0)
+                        return -errno;
+        }
+
+        if (socket_address_can_accept(a))
+                if (listen(fd, backlog) < 0)
+                        return -errno;
+
+        /* Let's trigger an inotify event on the socket node, so that anyone waiting for this socket to be connectable
+         * gets notified */
+        if (p)
+                (void) touch(p);
+
+        return TAKE_FD(fd);
+}