diff --git a/docs/CODING_STYLE.md b/docs/CODING_STYLE.md
index b8337fd097..e70c56b766 100644
--- a/docs/CODING_STYLE.md
+++ b/docs/CODING_STYLE.md
@@ -373,12 +373,16 @@
   something some time", or so is a lazy excuse. Always wait for the
   proper event, instead of doing time-based poll loops.
 
-- To determine the length of a constant string `"foo"`, don't bother
-  with `sizeof("foo")-1`, please use `STRLEN()` instead.
+- To determine the length of a constant string `"foo"`, don't bother with
+  `sizeof("foo")-1`, please use `strlen()` instead (both gcc and clang optimize
+  the call away for fixed strings). The only exception is when declaring an
+  array. In that case use STRLEN, which evalutates to a static constant and
+  doesn't force the compiler to create a VLA.
 
-- If you want to concatenate two or more strings, consider using
-  `strjoin()` rather than `asprintf()`, as the latter is a lot
-  slower. This matters particularly in inner loops.
+- If you want to concatenate two or more strings, consider using `strjoina()`
+  or `strjoin()` rather than `asprintf()`, as the latter is a lot slower. This
+  matters particularly in inner loops (but note that `strjoina()` cannot be
+  used there).
 
 - Please avoid using global variables as much as you can. And if you
   do use them make sure they are static at least, instead of
@@ -431,12 +435,13 @@
   want to call it "big endian" right-away.
 
 - You might wonder what kind of common code belongs in `src/shared/` and what
-  belongs in `src/basic/`. The split is like this: anything that uses public APIs
-  we expose (i.e. any of the sd-bus, sd-login, sd-id128, ... APIs) must be
-  located in `src/shared/`. All stuff that only uses external libraries from
-  other projects (such as glibc's APIs), or APIs from `src/basic/` itself should
-  be placed in `src/basic/`. Conversely, `src/libsystemd/` may only use symbols
-  from `src/basic`, but not from `src/shared/`.
+  belongs in `src/basic/`. The split is like this: anything that is used to
+  implement the public shared object we provide (sd-bus, sd-login, sd-id128,
+  nss-systemd, nss-mymachines, nss-resolve, nss-myhostname, pam_systemd), must
+  be located in `src/basic` (those objects are not allowed to link to
+  libsystemd-shared.so). Conversly, anything which is shared between multiple
+  components and does not need to be in `src/basic/`, should be in
+  `src/shared/`.
 
   To summarize:
 
@@ -449,7 +454,9 @@
   - may not use any code outside of `src/basic/`, `src/libsystemd/`
 
   `src/shared/`
-  - may be used by all code in the tree, except for code in `src/basic/`, `src/libsystemd/`
+  - may be used by all code in the tree, except for code in `src/basic/`,
+    `src/libsystemd/`, `src/nss-*`, `src/login/pam_systemd.*`, and files under
+    `src/journal/` that end up in `libjournal-client.a` convenience library.
   - may not use any code outside of `src/basic/`, `src/libsystemd/`, `src/shared/`
 
 - Our focus is on the GNU libc (glibc), not any other libcs. If other libcs are
diff --git a/meson.build b/meson.build
index 906960fb71..b989c664b1 100644
--- a/meson.build
+++ b/meson.build
@@ -1666,7 +1666,7 @@ endif
 if conf.get('HAVE_BLKID') == 1
         executable('systemd-gpt-auto-generator',
                    'src/gpt-auto-generator/gpt-auto-generator.c',
-                   'src/basic/blkid-util.h',
+                   'src/shared/blkid-util.h',
                    include_directories : includes,
                    link_with : [libshared],
                    dependencies : libblkid,
diff --git a/src/basic/meson.build b/src/basic/meson.build
index 3e2325f41f..abd54db8cc 100644
--- a/src/basic/meson.build
+++ b/src/basic/meson.build
@@ -15,23 +15,14 @@ basic_sources = files('''
         async.h
         audit-util.c
         audit-util.h
-        barrier.c
-        barrier.h
-        bitmap.c
-        bitmap.h
-        blkid-util.h
         blockdev-util.c
         blockdev-util.h
-        bpf-program.c
-        bpf-program.h
         btrfs-ctree.h
         btrfs-util.c
         btrfs-util.h
         build.h
         bus-label.c
         bus-label.h
-        calendarspec.c
-        calendarspec.h
         cap-list.c
         cap-list.h
         capability-util.c
@@ -40,16 +31,10 @@ basic_sources = files('''
         cgroup-util.h
         chattr-util.c
         chattr-util.h
-        clock-util.c
-        clock-util.h
         conf-files.c
         conf-files.h
         copy.c
         copy.h
-        cpu-set-util.c
-        cpu-set-util.h
-        crypt-util.c
-        crypt-util.h
         def.h
         device-nodes.c
         device-nodes.h
@@ -63,20 +48,12 @@ basic_sources = files('''
         escape.h
         ether-addr-util.c
         ether-addr-util.h
-        exec-util.c
-        exec-util.h
-        exit-status.c
-        exit-status.h
         extract-word.c
         extract-word.h
         fd-util.c
         fd-util.h
-        fileio-label.c
-        fileio-label.h
         fileio.c
         fileio.h
-        format-table.c
-        format-table.h
         format-util.h
         fs-util.c
         fs-util.h
@@ -97,11 +74,6 @@ basic_sources = files('''
         io-util.c
         io-util.h
         ioprio.h
-        journal-importer.c
-        journal-importer.h
-        json-internal.h
-        json.c
-        json.h
         khash.c
         khash.h
         label.c
@@ -109,8 +81,6 @@ basic_sources = files('''
         list.h
         locale-util.c
         locale-util.h
-        lockfile-util.c
-        lockfile-util.h
         log.c
         log.h
         login-util.c
@@ -129,8 +99,6 @@ basic_sources = files('''
         nss-util.h
         ordered-set.c
         ordered-set.h
-        os-util.c
-        os-util.h
         pager.c
         pager.h
         parse-util.c
@@ -151,17 +119,11 @@ basic_sources = files('''
         ratelimit.h
         raw-clone.h
         raw-reboot.h
-        reboot-util.c
-        reboot-util.h
         refcnt.h
         replace-var.c
         replace-var.h
-        rlimit-util.c
-        rlimit-util.h
         rm-rf.c
         rm-rf.h
-        securebits-util.c
-        securebits-util.h
         securebits.h
         selinux-util.c
         selinux-util.h
@@ -175,8 +137,6 @@ basic_sources = files('''
         smack-util.c
         smack-util.h
         socket-label.c
-        socket-protocol-list.c
-        socket-protocol-list.h
         socket-util.c
         socket-util.h
         sparse-endian.h
@@ -213,16 +173,10 @@ basic_sources = files('''
         utf8.h
         util.c
         util.h
-        verbs.c
-        verbs.h
         virt.c
         virt.h
-        web-util.c
-        web-util.h
         xattr-util.c
         xattr-util.h
-        xml.c
-        xml.h
 '''.split())
 
 missing_h = files('missing.h')
@@ -315,7 +269,6 @@ libbasic = static_library(
         include_directories : includes,
         dependencies : [threads,
                         libcap,
-                        libblkid,
                         libmount,
                         libselinux,
                         libm],
diff --git a/src/journal/journal-file.c b/src/journal/journal-file.c
index 390996a815..1174a52a66 100644
--- a/src/journal/journal-file.c
+++ b/src/journal/journal-file.c
@@ -10,6 +10,8 @@
 #include <sys/uio.h>
 #include <unistd.h>
 
+#include "sd-event.h"
+
 #include "alloc-util.h"
 #include "btrfs-util.h"
 #include "chattr-util.h"
@@ -23,7 +25,6 @@
 #include "parse-util.h"
 #include "path-util.h"
 #include "random-util.h"
-#include "sd-event.h"
 #include "set.h"
 #include "stat-util.h"
 #include "string-util.h"
diff --git a/src/journal/journal-file.h b/src/journal/journal-file.h
index 09b7ba090d..29e324d8cf 100644
--- a/src/journal/journal-file.h
+++ b/src/journal/journal-file.h
@@ -4,16 +4,16 @@
 #include <inttypes.h>
 
 #if HAVE_GCRYPT
-#include <gcrypt.h>
+#  include <gcrypt.h>
 #endif
 
+#include "sd-event.h"
 #include "sd-id128.h"
 
 #include "hashmap.h"
 #include "journal-def.h"
 #include "macro.h"
 #include "mmap-cache.h"
-#include "sd-event.h"
 #include "sparse-endian.h"
 
 typedef struct JournalMetrics {
diff --git a/src/basic/barrier.c b/src/shared/barrier.c
similarity index 100%
rename from src/basic/barrier.c
rename to src/shared/barrier.c
diff --git a/src/basic/barrier.h b/src/shared/barrier.h
similarity index 100%
rename from src/basic/barrier.h
rename to src/shared/barrier.h
diff --git a/src/basic/bitmap.c b/src/shared/bitmap.c
similarity index 100%
rename from src/basic/bitmap.c
rename to src/shared/bitmap.c
diff --git a/src/basic/bitmap.h b/src/shared/bitmap.h
similarity index 100%
rename from src/basic/bitmap.h
rename to src/shared/bitmap.h
diff --git a/src/basic/blkid-util.h b/src/shared/blkid-util.h
similarity index 100%
rename from src/basic/blkid-util.h
rename to src/shared/blkid-util.h
diff --git a/src/basic/bpf-program.c b/src/shared/bpf-program.c
similarity index 100%
rename from src/basic/bpf-program.c
rename to src/shared/bpf-program.c
diff --git a/src/basic/bpf-program.h b/src/shared/bpf-program.h
similarity index 100%
rename from src/basic/bpf-program.h
rename to src/shared/bpf-program.h
diff --git a/src/basic/calendarspec.c b/src/shared/calendarspec.c
similarity index 100%
rename from src/basic/calendarspec.c
rename to src/shared/calendarspec.c
diff --git a/src/basic/calendarspec.h b/src/shared/calendarspec.h
similarity index 100%
rename from src/basic/calendarspec.h
rename to src/shared/calendarspec.h
diff --git a/src/basic/clock-util.c b/src/shared/clock-util.c
similarity index 100%
rename from src/basic/clock-util.c
rename to src/shared/clock-util.c
diff --git a/src/basic/clock-util.h b/src/shared/clock-util.h
similarity index 100%
rename from src/basic/clock-util.h
rename to src/shared/clock-util.h
diff --git a/src/basic/cpu-set-util.c b/src/shared/cpu-set-util.c
similarity index 100%
rename from src/basic/cpu-set-util.c
rename to src/shared/cpu-set-util.c
diff --git a/src/basic/cpu-set-util.h b/src/shared/cpu-set-util.h
similarity index 100%
rename from src/basic/cpu-set-util.h
rename to src/shared/cpu-set-util.h
diff --git a/src/basic/crypt-util.c b/src/shared/crypt-util.c
similarity index 100%
rename from src/basic/crypt-util.c
rename to src/shared/crypt-util.c
diff --git a/src/basic/crypt-util.h b/src/shared/crypt-util.h
similarity index 100%
rename from src/basic/crypt-util.h
rename to src/shared/crypt-util.h
diff --git a/src/basic/exec-util.c b/src/shared/exec-util.c
similarity index 100%
rename from src/basic/exec-util.c
rename to src/shared/exec-util.c
diff --git a/src/basic/exec-util.h b/src/shared/exec-util.h
similarity index 100%
rename from src/basic/exec-util.h
rename to src/shared/exec-util.h
diff --git a/src/basic/exit-status.c b/src/shared/exit-status.c
similarity index 100%
rename from src/basic/exit-status.c
rename to src/shared/exit-status.c
diff --git a/src/basic/exit-status.h b/src/shared/exit-status.h
similarity index 100%
rename from src/basic/exit-status.h
rename to src/shared/exit-status.h
diff --git a/src/basic/fileio-label.c b/src/shared/fileio-label.c
similarity index 100%
rename from src/basic/fileio-label.c
rename to src/shared/fileio-label.c
diff --git a/src/basic/fileio-label.h b/src/shared/fileio-label.h
similarity index 100%
rename from src/basic/fileio-label.h
rename to src/shared/fileio-label.h
diff --git a/src/basic/format-table.c b/src/shared/format-table.c
similarity index 100%
rename from src/basic/format-table.c
rename to src/shared/format-table.c
diff --git a/src/basic/format-table.h b/src/shared/format-table.h
similarity index 100%
rename from src/basic/format-table.h
rename to src/shared/format-table.h
diff --git a/src/basic/journal-importer.c b/src/shared/journal-importer.c
similarity index 100%
rename from src/basic/journal-importer.c
rename to src/shared/journal-importer.c
diff --git a/src/basic/journal-importer.h b/src/shared/journal-importer.h
similarity index 100%
rename from src/basic/journal-importer.h
rename to src/shared/journal-importer.h
diff --git a/src/basic/json-internal.h b/src/shared/json-internal.h
similarity index 100%
rename from src/basic/json-internal.h
rename to src/shared/json-internal.h
diff --git a/src/basic/json.c b/src/shared/json.c
similarity index 100%
rename from src/basic/json.c
rename to src/shared/json.c
diff --git a/src/basic/json.h b/src/shared/json.h
similarity index 100%
rename from src/basic/json.h
rename to src/shared/json.h
diff --git a/src/basic/lockfile-util.c b/src/shared/lockfile-util.c
similarity index 100%
rename from src/basic/lockfile-util.c
rename to src/shared/lockfile-util.c
diff --git a/src/basic/lockfile-util.h b/src/shared/lockfile-util.h
similarity index 100%
rename from src/basic/lockfile-util.h
rename to src/shared/lockfile-util.h
diff --git a/src/shared/meson.build b/src/shared/meson.build
index c692f012b1..f7f63a5404 100644
--- a/src/shared/meson.build
+++ b/src/shared/meson.build
@@ -8,24 +8,39 @@ shared_sources = files('''
         apparmor-util.h
         ask-password-api.c
         ask-password-api.h
+        barrier.c
+        barrier.h
         base-filesystem.c
         base-filesystem.h
+        bitmap.c
+        bitmap.h
+        blkid-util.h
         boot-timestamps.c
         boot-timestamps.h
         bootspec.c
         bootspec.h
+        bpf-program.c
+        bpf-program.h
         bus-unit-util.c
         bus-unit-util.h
         bus-util.c
         bus-util.h
+        calendarspec.c
+        calendarspec.h
         cgroup-show.c
         cgroup-show.h
         clean-ipc.c
         clean-ipc.h
+        clock-util.c
+        clock-util.h
         condition.c
         condition.h
         conf-parser.c
         conf-parser.h
+        cpu-set-util.c
+        cpu-set-util.h
+        crypt-util.c
+        crypt-util.h
         dev-setup.c
         dev-setup.h
         dissect-image.c
@@ -37,9 +52,17 @@ shared_sources = files('''
         efivars.c
         efivars.h
         enable-mempool.c
+        exec-util.c
+        exec-util.h
+        exit-status.c
+        exit-status.h
         fdset.c
         fdset.h
+        fileio-label.c
+        fileio-label.h
         firewall-util.h
+        format-table.c
+        format-table.h
         fstab-util.c
         fstab-util.h
         generator.c
@@ -56,8 +79,15 @@ shared_sources = files('''
         install-printf.h
         install.c
         install.h
+        journal-importer.c
+        journal-importer.h
         journal-util.c
         journal-util.h
+        json-internal.h
+        json.c
+        json.h
+        lockfile-util.c
+        lockfile-util.h
         logs-show.c
         logs-show.h
         loop-util.c
@@ -69,19 +99,29 @@ shared_sources = files('''
         module-util.h
         nsflags.c
         nsflags.h
+        os-util.c
+        os-util.h
         output-mode.c
         output-mode.h
         path-lookup.c
         path-lookup.h
         ptyfwd.c
         ptyfwd.h
+        reboot-util.c
+        reboot-util.h
         resolve-util.c
         resolve-util.h
+        rlimit-util.c
+        rlimit-util.h
         seccomp-util.h
+        securebits-util.c
+        securebits-util.h
         serialize.c
         serialize.h
         sleep-config.c
         sleep-config.h
+        socket-protocol-list.c
+        socket-protocol-list.h
         spawn-ask-password-agent.c
         spawn-ask-password-agent.h
         spawn-polkit-agent.c
@@ -99,13 +139,19 @@ shared_sources = files('''
         uid-range.c
         uid-range.h
         utmp-wtmp.h
+        verbs.c
+        verbs.h
         vlan-util.c
         vlan-util.h
         volatile-util.c
         volatile-util.h
         watchdog.c
         watchdog.h
+        web-util.c
+        web-util.h
         wireguard-netlink.h
+        xml.c
+        xml.h
 '''.split())
 
 if get_option('tests') != 'false'
diff --git a/src/basic/os-util.c b/src/shared/os-util.c
similarity index 100%
rename from src/basic/os-util.c
rename to src/shared/os-util.c
diff --git a/src/basic/os-util.h b/src/shared/os-util.h
similarity index 100%
rename from src/basic/os-util.h
rename to src/shared/os-util.h
diff --git a/src/basic/reboot-util.c b/src/shared/reboot-util.c
similarity index 100%
rename from src/basic/reboot-util.c
rename to src/shared/reboot-util.c
diff --git a/src/basic/reboot-util.h b/src/shared/reboot-util.h
similarity index 100%
rename from src/basic/reboot-util.h
rename to src/shared/reboot-util.h
diff --git a/src/basic/rlimit-util.c b/src/shared/rlimit-util.c
similarity index 100%
rename from src/basic/rlimit-util.c
rename to src/shared/rlimit-util.c
diff --git a/src/basic/rlimit-util.h b/src/shared/rlimit-util.h
similarity index 100%
rename from src/basic/rlimit-util.h
rename to src/shared/rlimit-util.h
diff --git a/src/basic/securebits-util.c b/src/shared/securebits-util.c
similarity index 100%
rename from src/basic/securebits-util.c
rename to src/shared/securebits-util.c
diff --git a/src/basic/securebits-util.h b/src/shared/securebits-util.h
similarity index 100%
rename from src/basic/securebits-util.h
rename to src/shared/securebits-util.h
diff --git a/src/basic/socket-protocol-list.c b/src/shared/socket-protocol-list.c
similarity index 100%
rename from src/basic/socket-protocol-list.c
rename to src/shared/socket-protocol-list.c
diff --git a/src/basic/socket-protocol-list.h b/src/shared/socket-protocol-list.h
similarity index 100%
rename from src/basic/socket-protocol-list.h
rename to src/shared/socket-protocol-list.h
diff --git a/src/basic/verbs.c b/src/shared/verbs.c
similarity index 100%
rename from src/basic/verbs.c
rename to src/shared/verbs.c
diff --git a/src/basic/verbs.h b/src/shared/verbs.h
similarity index 100%
rename from src/basic/verbs.h
rename to src/shared/verbs.h
diff --git a/src/basic/web-util.c b/src/shared/web-util.c
similarity index 100%
rename from src/basic/web-util.c
rename to src/shared/web-util.c
diff --git a/src/basic/web-util.h b/src/shared/web-util.h
similarity index 100%
rename from src/basic/web-util.h
rename to src/shared/web-util.h
diff --git a/src/basic/xml.c b/src/shared/xml.c
similarity index 100%
rename from src/basic/xml.c
rename to src/shared/xml.c
diff --git a/src/basic/xml.h b/src/shared/xml.h
similarity index 100%
rename from src/basic/xml.h
rename to src/shared/xml.h