sd-daemon: introduce sd_booted() and set ELF visibility to hidden for all symbols

3 files changed, 194 insertions, 119 deletions

diff --git a/src/macro.h b/src/macro.h
index 763a4de27a..d00e70bf6d 100644
--- a/src/macro.h
+++ b/src/macro.h
@@ -38,6 +38,8 @@
 #define _weak_ __attribute__ ((weak))
 #define _likely_(x) (__builtin_expect(!!(x),1))
 #define _unlikely_(x) (__builtin_expect(!!(x),0))
+#define _public_ __attribute__ ((visibility("default")))
+#define _hidden_ __attribute__ ((visibility("hidden")))
 
 /* Rounds up */
 static inline size_t ALIGN(size_t l) {
diff --git a/src/sd-daemon.c b/src/sd-daemon.c
index e6b9a6f3c2..cb568b5e65 100644
--- a/src/sd-daemon.c
+++ b/src/sd-daemon.c
@@ -426,3 +426,23 @@ int sd_notifyf(int unset_environment, const char *format, ...) {
         return r;
 #endif
 }
+
+int sd_booted(void) {
+#if defined(DISABLE_SYSTEMD) || !defined(__linux__)
+        return 0;
+#else
+
+        struct stat a, b;
+
+        /* We simply test whether the systemd cgroup hierarchy is
+         * mounted */
+
+        if (lstat("/cgroup", &a) < 0)
+                return 0;
+
+        if (lstat("/cgroup/systemd", &b) < 0)
+                return 0;
+
+        return a.st_dev != b.st_dev;
+#endif
+}
diff --git a/src/sd-daemon.h b/src/sd-daemon.h
index 20c260c40d..dc18f42eaa 100644
--- a/src/sd-daemon.h
+++ b/src/sd-daemon.h
@@ -34,17 +34,43 @@
 extern "C" {
 #endif
 
-/* Reference implementation of a few systemd related interfaces for
- * writing daemons. These interfaces are trivial to implement. To
- * simplify porting we provide this reference
- * implementation. Applications are welcome to reimplement the
- * algorithms described here, if they do not want to include these two
- * source files. */
-
-#ifdef __GNUC__
+/*
+  Reference implementation of a few systemd related interfaces for
+  writing daemons. These interfaces are trivial to implement. To
+  simplify porting we provide this reference implementation.
+  Applications are welcome to reimplement the algorithms described
+  here if they do not want to include these two source files.
+
+  The following functionality is provided:
+
+  - Support for logging with log levels on stderr
+  - File descriptor passing for socket-based activation
+  - Daemon startup and status notification
+  - Detection of systemd boots
+
+  You may compile this with -DDISABLE_SYSTEMD to disable systemd
+  support. This make all those calls NOPs that are directly related to
+  systemd (i.e. only sd_is_xxx() will stay useful).
+
+  Since this is drop-in code we don't want any of our symbols to be
+  exported in any case. Hence we declare hidden visibility for all of
+  them.
+
+  You may find an up-to-date version of these source files online:
+
+  http://cgit.freedesktop.org/systemd/plain/src/sd-daemon.h
+  http://cgit.freedesktop.org/systemd/plain/src/sd-daemon.c
+
+  This should compile on non-Linux systems, too, but with the
+  exception of the sd_is_xxx() calls all functions will become NOPs.
+*/
+
+#if __GNUC__ >= 4
 #define _sd_printf_attr_(a,b) __attribute__ ((format (printf, a, b)))
+#define _sd_hidden_ __attribute__ ((visibility("hidden")))
 #else
 #define _sd_printf_attr_(a,b)
+#define _sd_hidden_
 #endif
 
 /*
@@ -54,7 +80,6 @@ extern "C" {
 
   This is similar to printk() usage in the kernel.
 */
-
 #define SD_EMERG   "<0>"  /* system is unusable */
 #define SD_ALERT   "<1>"  /* action must be taken immediately */
 #define SD_CRIT    "<2>"  /* critical conditions */
@@ -67,116 +92,144 @@ extern "C" {
 /* The first passed file descriptor is fd 3 */
 #define SD_LISTEN_FDS_START 3
 
-/* Returns how many file descriptors have been passed, or a negative
- * errno code on failure. Optionally, removes the $LISTEN_FDS and
- * $LISTEN_PID file descriptors from the environment (recommended, but
- * problematic in threaded environments). If r is the return value of
- * this function you'll find the file descriptors passed as fds
- * SD_LISTEN_FDS_START to SD_LISTEN_FDS_START+r-1. Returns a negative
- * errno style error code on failure. This function call ensures that
- * the FD_CLOEXEC flag is set for the passed file descriptors, to make
- * sure they are not passed on to child processes. If FD_CLOEXEC shall
- * not be set, the caller needs to unset it after this call for all file
- * descriptors that are used.*/
-int sd_listen_fds(int unset_environment);
-
-/* Helper call for identifying a passed file descriptor. Returns 1 if
- * the file descriptor is a FIFO in the file system stored under the
- * specified path, 0 otherwise. If path is NULL a path name check will
- * not be done and the call only verifies if the file descriptor
- * refers to a FIFO. Returns a negative errno style error code on
- * failure. */
-int sd_is_fifo(int fd, const char *path);
-
-/* Helper call for identifying a passed file descriptor. Returns 1 if
- * the file descriptor is a socket of the specified family (AF_INET,
- * ...) and type (SOCK_DGRAM, SOCK_STREAM, ...), 0 otherwise. If
- * family is 0 a socket family check will not be done. If type is 0 a
- * socket type check will not be done and the call only verifies if
- * the file descriptor refers to a socket. If listening is > 0 it is
- * verified that the socket is in listening mode. (i.e. listen() has
- * been called) If listening is == 0 it is verified that the socket is
- * not in listening mode. If listening is < 0 no listening mode check
- * is done. Returns a negative errno style error code on failure. */
-int sd_is_socket(int fd, int family, int type, int listening);
-
-/* Helper call for identifying a passed file descriptor. Returns 1 if
- * the file descriptor is an Internet socket, of the specified family
- * (either AF_INET or AF_INET6) and the specified type (SOCK_DGRAM,
- * SOCK_STREAM, ...), 0 otherwise. If version is 0 a protocol version
- * check is not done. If type is 0 a socket type check will not be
- * done. If port is 0 a socket port check will not be done. The
- * listening flag is used the same way as in sd_is_socket(). Returns a
- * negative errno style error code on failure. */
-int sd_is_socket_inet(int fd, int family, int type, int listening, uint16_t port);
-
-/* Helper call for identifying a passed file descriptor. Returns 1 if
- * the file descriptor is an AF_UNIX socket of the specified type
- * (SOCK_DGRAM, SOCK_STREAM, ...) and path, 0 otherwise. If type is 0
- * a socket type check will not be done. If path is NULL a socket path
- * check will not be done. For normal AF_UNIX sockets set length to
- * 0. For abstract namespace sockets set length to the length of the
- * socket name (including the initial 0 byte), and pass the full
- * socket path in path (including the initial 0 byte). The listening
- * flag is used the same way as in sd_is_socket(). Returns a negative
- * errno style error code on failure. */
-int sd_is_socket_unix(int fd, int type, int listening, const char *path, size_t length);
-
-/* Informs systemd about changed daemon state. This takes a numeber of
- * newline seperated environment-style variable assignments in a
- * string. The following strings are known:
- *
- *    READY=1      Tells systemd that daemon startup is finished (only
- *                 relevant for services of Type=notify). The passed
- *                 argument is a boolean "1" or "0". Since there is
- *                 little value in signalling non-readiness the only
- *                 value daemons should send is "READY=1".
- *
- *    STATUS=...   Passes a single-line status string back to systemd
- *                 that describes the daemon state. This is free-from
- *                 and can be used for various purposes: general state
- *                 feedback, fsck-like programs could pass completion
- *                 percentages and failing programs could pass a human
- *                 readable error message. Example: "STATUS=Completed
- *                 66% of file system check..."
- *
- *    ERRNO=...    If a daemon fails, the errno-style error code,
- *                 formatted as string. Example: "ERRNO=2" for ENOENT.
- *
- *    BUSERROR=... If a daemon fails, the D-Bus error-style error
- *                 code. Example: "BUSERROR=org.freedesktop.DBus.Error.TimedOut"
- *
- *    MAINPID=...  The main pid of a daemon, in case systemd did not
- *                 fork off the process itself. Example: "MAINPID=4711"
- *
- * Daemons can choose to send additional variables.
- *
- * Returns a negative errno-style error code on failure. Returns > 0
- * if systemd could be notified, 0 if it couldn't possibly because
- * systemd is not running.
- *
- * See sd_notifyf() for more complete examples.
- */
-int sd_notify(int unset_environment, const char *state);
-
-/* Similar to sd_send_state() but takes a format string.
- *
- * Example 1: A daemon could send the following after initialization:
- *
- * sd_notifyf(0, "READY=1\n"
- *               "STATUS=Processing requests...\n"
- *               "MAINPID=%lu",
- *               (unsigned long) getpid());
- *
- * Example 2: A daemon could send the following shortly before
- * exiting, on failure:
- *
- * sd_notifyf(0, "STATUS=Failed to start up: %s\n"
- *               "ERRNO=%i",
- *               strerror(errno),
- *               errno);
- */
-int sd_notifyf(int unset_environment, const char *format, ...) _sd_printf_attr_(2,3);
+/*
+  Returns how many file descriptors have been passed, or a negative
+  errno code on failure. Optionally, removes the $LISTEN_FDS and
+  $LISTEN_PID file descriptors from the environment (recommended, but
+  problematic in threaded environments). If r is the return value of
+  this function you'll find the file descriptors passed as fds
+  SD_LISTEN_FDS_START to SD_LISTEN_FDS_START+r-1. Returns a negative
+  errno style error code on failure. This function call ensures that
+  the FD_CLOEXEC flag is set for the passed file descriptors, to make
+  sure they are not passed on to child processes. If FD_CLOEXEC shall
+  not be set, the caller needs to unset it after this call for all file
+  descriptors that are used.
+*/
+int sd_listen_fds(int unset_environment) _sd_hidden_;
+
+/*
+  Helper call for identifying a passed file descriptor. Returns 1 if
+  the file descriptor is a FIFO in the file system stored under the
+  specified path, 0 otherwise. If path is NULL a path name check will
+  not be done and the call only verifies if the file descriptor
+  refers to a FIFO. Returns a negative errno style error code on
+  failure.
+*/
+int sd_is_fifo(int fd, const char *path) _sd_hidden_;
+
+/*
+  Helper call for identifying a passed file descriptor. Returns 1 if
+  the file descriptor is a socket of the specified family (AF_INET,
+  ...) and type (SOCK_DGRAM, SOCK_STREAM, ...), 0 otherwise. If
+  family is 0 a socket family check will not be done. If type is 0 a
+  socket type check will not be done and the call only verifies if
+  the file descriptor refers to a socket. If listening is > 0 it is
+  verified that the socket is in listening mode. (i.e. listen() has
+  been called) If listening is == 0 it is verified that the socket is
+  not in listening mode. If listening is < 0 no listening mode check
+  is done. Returns a negative errno style error code on failure.
+*/
+int sd_is_socket(int fd, int family, int type, int listening) _sd_hidden_;
+
+/*
+  Helper call for identifying a passed file descriptor. Returns 1 if
+  the file descriptor is an Internet socket, of the specified family
+  (either AF_INET or AF_INET6) and the specified type (SOCK_DGRAM,
+  SOCK_STREAM, ...), 0 otherwise. If version is 0 a protocol version
+  check is not done. If type is 0 a socket type check will not be
+  done. If port is 0 a socket port check will not be done. The
+  listening flag is used the same way as in sd_is_socket(). Returns a
+  negative errno style error code on failure.
+*/
+int sd_is_socket_inet(int fd, int family, int type, int listening, uint16_t port) _sd_hidden_;
+
+/*
+  Helper call for identifying a passed file descriptor. Returns 1 if
+  the file descriptor is an AF_UNIX socket of the specified type
+  (SOCK_DGRAM, SOCK_STREAM, ...) and path, 0 otherwise. If type is 0
+  a socket type check will not be done. If path is NULL a socket path
+  check will not be done. For normal AF_UNIX sockets set length to
+  0. For abstract namespace sockets set length to the length of the
+  socket name (including the initial 0 byte), and pass the full
+  socket path in path (including the initial 0 byte). The listening
+  flag is used the same way as in sd_is_socket(). Returns a negative
+  errno style error code on failure.
+*/
+int sd_is_socket_unix(int fd, int type, int listening, const char *path, size_t length) _sd_hidden_;
+
+/*
+  Informs systemd about changed daemon state. This takes a numeber of
+  newline seperated environment-style variable assignments in a
+  string. The following strings are known:
+
+     READY=1      Tells systemd that daemon startup is finished (only
+                  relevant for services of Type=notify). The passed
+                  argument is a boolean "1" or "0". Since there is
+                  little value in signalling non-readiness the only
+                  value daemons should send is "READY=1".
+
+     STATUS=...   Passes a single-line status string back to systemd
+                  that describes the daemon state. This is free-from
+                  and can be used for various purposes: general state
+                  feedback, fsck-like programs could pass completion
+                  percentages and failing programs could pass a human
+                  readable error message. Example: "STATUS=Completed
+                  66% of file system check..."
+
+     ERRNO=...    If a daemon fails, the errno-style error code,
+                  formatted as string. Example: "ERRNO=2" for ENOENT.
+
+     BUSERROR=... If a daemon fails, the D-Bus error-style error
+                  code. Example: "BUSERROR=org.freedesktop.DBus.Error.TimedOut"
+
+     MAINPID=...  The main pid of a daemon, in case systemd did not
+                  fork off the process itself. Example: "MAINPID=4711"
+
+  Daemons can choose to send additional variables.
+
+  Returns a negative errno-style error code on failure. Returns > 0
+  if systemd could be notified, 0 if it couldn't possibly because
+  systemd is not running.
+
+  Example: When a daemon finished starting up, it could issue this
+  call to notify systemd about it:
+
+     sd_notify(0, "READY=1");
+
+  See sd_notifyf() for more complete examples.
+*/
+int sd_notify(int unset_environment, const char *state) _sd_hidden_;
+
+/*
+  Similar to sd_notify() but takes a format string.
+
+  Example 1: A daemon could send the following after initialization:
+
+     sd_notifyf(0, "READY=1\n"
+                   "STATUS=Processing requests...\n"
+                   "MAINPID=%lu",
+                   (unsigned long) getpid());
+
+  Example 2: A daemon could send the following shortly before
+  exiting, on failure:
+
+     sd_notifyf(0, "STATUS=Failed to start up: %s\n"
+                   "ERRNO=%i",
+                   strerror(errno),
+                   errno);
+*/
+int sd_notifyf(int unset_environment, const char *format, ...) _sd_printf_attr_(2,3) _sd_hidden_;
+
+/*
+  Returns > 0 if the system was booted with systemd. Returns < 0 on
+  error. Returns 0 if the system was not booted with systemd. Note
+  that all of the functions above handle non-systemd boots just
+  fine. You should NOT protect them with a call to this function. Also
+  note that this function checks whether the system, not the user
+  session is controlled by systemd. However the functions above work
+  for both session and system services.
+*/
+int sd_booted(void) _sd_hidden_;
 
 #ifdef __cplusplus
 }