util: move all to shared/ and split external dependencies in separate internal libraries

Before:
  $ ldd /lib/systemd/systemd-timestamp
  linux-vdso.so.1 =>  (0x00007fffb05ff000)
  libselinux.so.1 => /lib64/libselinux.so.1 (0x00007f90aac57000)
  libcap.so.2 => /lib64/libcap.so.2 (0x00007f90aaa53000)
  librt.so.1 => /lib64/librt.so.1 (0x00007f90aa84a000)
  libc.so.6 => /lib64/libc.so.6 (0x00007f90aa494000)
  /lib64/ld-linux-x86-64.so.2 (0x00007f90aae90000)
  libdl.so.2 => /lib64/libdl.so.2 (0x00007f90aa290000)
  libattr.so.1 => /lib64/libattr.so.1 (0x00007f90aa08a000)
  libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f90a9e6e000)

After:
  $ ldd systemd-timestamp
  linux-vdso.so.1 =>  (0x00007fff3cbff000)
  libselinux.so.1 => /lib64/libselinux.so.1 (0x00007f5eaa1c3000)
  librt.so.1 => /lib64/librt.so.1 (0x00007f5ea9fbb000)
  libc.so.6 => /lib64/libc.so.6 (0x00007f5ea9c04000)
  /lib64/ld-linux-x86-64.so.2 (0x00007f5eaa3fc000)
  libdl.so.2 => /lib64/libdl.so.2 (0x00007f5ea9a00000)
  libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f5ea97e4000)

1 files changed, 118 insertions, 0 deletions

diff --git a/src/shared/audit.c b/src/shared/audit.c
new file mode 100644
index 000000000..385005913
--- /dev/null
+++ b/src/shared/audit.c
@@ -0,0 +1,118 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <assert.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <ctype.h>
+#include <sys/prctl.h>
+#include <sys/capability.h>
+
+#include "macro.h"
+#include "audit.h"
+#include "util.h"
+#include "log.h"
+
+int audit_session_from_pid(pid_t pid, uint32_t *id) {
+        char *s;
+        uint32_t u;
+        int r;
+
+        assert(id);
+
+        if (have_effective_cap(CAP_AUDIT_CONTROL) <= 0)
+                return -ENOENT;
+
+        if (pid == 0)
+                r = read_one_line_file("/proc/self/sessionid", &s);
+        else {
+                char *p;
+
+                if (asprintf(&p, "/proc/%lu/sessionid", (unsigned long) pid) < 0)
+                        return -ENOMEM;
+
+                r = read_one_line_file(p, &s);
+                free(p);
+        }
+
+        if (r < 0)
+                return r;
+
+        r = safe_atou32(s, &u);
+        free(s);
+
+        if (r < 0)
+                return r;
+
+        if (u == (uint32_t) -1 || u <= 0)
+                return -ENOENT;
+
+        *id = u;
+        return 0;
+}
+
+int audit_loginuid_from_pid(pid_t pid, uid_t *uid) {
+        char *s;
+        uid_t u;
+        int r;
+
+        assert(uid);
+
+        /* Only use audit login uid if we are executed with sufficient
+         * capabilities so that pam_loginuid could do its job. If we
+         * are lacking the CAP_AUDIT_CONTROL capabality we most likely
+         * are being run in a container and /proc/self/loginuid is
+         * useless since it probably contains a uid of the host
+         * system. */
+
+        if (have_effective_cap(CAP_AUDIT_CONTROL) <= 0)
+                return -ENOENT;
+
+        if (pid == 0)
+                r = read_one_line_file("/proc/self/loginuid", &s);
+        else {
+                char *p;
+
+                if (asprintf(&p, "/proc/%lu/loginuid", (unsigned long) pid) < 0)
+                        return -ENOMEM;
+
+                r = read_one_line_file(p, &s);
+                free(p);
+        }
+
+        if (r < 0)
+                return r;
+
+        r = parse_uid(s, &u);
+        free(s);
+
+        if (r < 0)
+                return r;
+
+        if (u == (uid_t) -1)
+                return -ENOENT;
+
+        *uid = (uid_t) u;
+        return 0;
+}