#if APR_HAS_FORK
/**
 * This is currently the only non-portable call in APR.  This executes 
 * a standard unix fork.
 * @param proc The resulting process handle. 
 * @param cont The pool to use. 
 */
APR_DECLARE(apr_status_t) apr_proc_fork(apr_proc_t *proc, apr_pool_t *cont);
#endif

/**
 * Create a new process and execute a new program within that process.
 * @param new_proc The resulting process handle.
 * @param progname The program to run 
 * @param args the arguments to pass to the new program.  The first 
 *             one should be the program name.
 * @param env The new environment table for the new process.  This 
 *            should be a list of NULL-terminated strings. This argument
 *            is ignored for APR_PROGRAM_ENV, APR_PROGRAM_PATH, and
 *            APR_SHELLCMD_ENV types of commands.
 * @param attr the procattr we should use to determine how to create the new
 *         process
 * @param cont The pool to use. 
 */
APR_DECLARE(apr_status_t) apr_proc_create(apr_proc_t *new_proc,
                                             const char *progname,
                                             const char * const *args,
                                             const char * const *env, 
                                             apr_procattr_t *attr, 
                                             apr_pool_t *cont);

/**
 * Wait for a child process to die
 * @param proc The process handle that corresponds to the desired child process 
 * @param exitcode The returned exit status of the child, if a child process 
 *                 dies, or the signal that caused the child to die.
 *                 On platforms that don't support obtaining this information, 
 *                 the status parameter will be returned as APR_ENOTIMPL.
 * @param exitwhy Why the child died, the bitwise or of:
 * <PRE>
 *            APR_PROC_EXIT         -- process terminated normally
 *            APR_PROC_SIGNAL       -- process was killed by a signal
 *            APR_PROC_SIGNAL_CORE  -- process was killed by a signal, and
 *                                     generated a core dump.
 * </PRE>
 * @param waithow How should we wait.  One of:
 * <PRE>
 *            APR_WAIT   -- block until the child process dies.
 *            APR_NOWAIT -- return immediately regardless of if the 
 *                          child is dead or not.
 * </PRE>
 * @remark The childs status is in the return code to this process.  It is one of:
 * <PRE>
 *            APR_CHILD_DONE     -- child is no longer running.
 *            APR_CHILD_NOTDONE  -- child is still running.
 * </PRE>
 */
APR_DECLARE(apr_status_t) apr_proc_wait(apr_proc_t *proc,
                                        int *exitcode, apr_exit_why_e *exitwhy,
                                        apr_wait_how_e waithow);

/**
 * Wait for any current child process to die and return information 
 * about that child.
 * @param proc Pointer to NULL on entry, will be filled out with child's 
 *             information 
 * @param exitcode The returned exit status of the child, if a child process 
 *                 dies, or the signal that caused the child to die.
 *                 On platforms that don't support obtaining this information, 
 *                 the status parameter will be returned as APR_ENOTIMPL.
 * @param exitwhy Why the child died, the bitwise or of:
 * <PRE>
 *            APR_PROC_EXIT         -- process terminated normally
 *            APR_PROC_SIGNAL       -- process was killed by a signal
 *            APR_PROC_SIGNAL_CORE  -- process was killed by a signal, and
 *                                     generated a core dump.
 * </PRE>
 * @param waithow How should we wait.  One of:
 * <PRE>
 *            APR_WAIT   -- block until the child process dies.
 *            APR_NOWAIT -- return immediately regardless of if the 
 *                          child is dead or not.
 * </PRE>
 * @param p Pool to allocate child information out of.
 * @bug Passing proc as a *proc rather than **proc was an odd choice
 * for some platforms... this should be revisited in 1.0
 */
APR_DECLARE(apr_status_t) apr_proc_wait_all_procs(apr_proc_t *proc,
                                                  int *exitcode,
                                                  apr_exit_why_e *exitwhy,
                                                  apr_wait_how_e waithow,
                                                  apr_pool_t *p);

#define APR_PROC_DETACH_FOREGROUND 0    /**< Do not detach */
#define APR_PROC_DETACH_DAEMONIZE 1     /**< Detach */

/**
 * Detach the process from the controlling terminal.
 * @param daemonize set to non-zero if the process should daemonize
 *                  and become a background process, else it will
 *                  stay in the foreground.
 */
APR_DECLARE(apr_status_t) apr_proc_detach(int daemonize);

/**
 * Register an other_child -- a child associated to its registered 
 * maintence callback.  This callback is invoked when the process
 * dies, is disconnected or disappears.
 * @param proc The child process to register.
 * @param maintenance maintenance is a function that is invoked with a 
 *                    reason and the data pointer passed here.
 * @param data Opaque context data passed to the maintenance function.
 * @param write_fd An fd that is probed for writing.  If it is ever unwritable
 *                 then the maintenance is invoked with reason 
 *                 OC_REASON_UNWRITABLE.
 * @param p The pool to use for allocating memory.
 * @bug write_fd duplicates the proc->out stream, it's really redundant
 * and should be replaced in the APR 1.0 API with a bitflag of which
 * proc->in/out/err handles should be health checked.
 * @bug no platform currently tests the pipes health.
 */
APR_DECLARE(void) apr_proc_other_child_register(apr_proc_t *proc, 
                                           void (*maintenance) (int reason, 
                                                                void *, 
                                                                int status),
                                           void *data, apr_file_t *write_fd,
                                           apr_pool_t *p);

/**
 * Stop watching the specified other child.  
 * @param data The data to pass to the maintenance function.  This is
 *             used to find the process to unregister.
 * @warning Since this can be called by a maintenance function while we're
 *          scanning the other_children list, all scanners should protect 
 *          themself by loading ocr->next before calling any maintenance 
 *          function.
 */
APR_DECLARE(void) apr_proc_other_child_unregister(void *data);

/**
 * Notify the maintenance callback of a registered other child process
 * that application has detected an event, such as death.
 * @param proc The process to check
 * @param reason The reason code to pass to the maintenance function
 * @param status The status to pass to the maintenance function
 * @remark An example of code using this behavior;
 * <pre>
 * rv = apr_proc_wait_all_procs(&proc, &exitcode, &status, APR_WAIT, p);
 * if (APR_STATUS_IS_CHILD_DONE(rv)) {
 * #if APR_HAS_OTHER_CHILD
 *     if (apr_proc_other_child_alert(&proc, APR_OC_REASON_DEATH, status)
 *             == APR_SUCCESS) {
 *         ;  (already handled)
 *     }
 *     else
 * #endif
 *         [... handling non-otherchild processes death ...]
 * </pre>
 */
APR_DECLARE(apr_status_t) apr_proc_other_child_alert(apr_proc_t *proc, 
                                                     int reason,
                                                     int status);

/**
 * Test one specific other child processes and invoke the maintenance callback 
 * with the appropriate reason code, if still running, or the appropriate reason 
 * code if the process is no longer healthy.
 * @param ocr The registered other child
 * @param reason The reason code (e.g. APR_OC_REASON_RESTART) if still running
 */
APR_DECLARE(void) apr_proc_other_child_refresh(apr_other_child_rec_t *ocr,
                                               int reason);

/**
 * Test all registered other child processes and invoke the maintenance callback 
 * with the appropriate reason code, if still running, or the appropriate reason 
 * code if the process is no longer healthy.
 * @param reason The reason code (e.g. APR_OC_REASON_RESTART) to running processes
 */
APR_DECLARE(void) apr_proc_other_child_refresh_all(int reason);

/** @deprecated @see apr_proc_other_child_refresh_all
 * @remark Call apr_proc_other_child_refresh_all(APR_OC_REASON_RESTART)
 * or apr_proc_other_child_refresh_all(APR_OC_REASON_RUNNING) instead.
 * @bug The differing implementations of this function on Win32 (_RUNNING checks) 
 * and Unix (used only for _RESTART) are the reason it will be dropped with APR 1.0.
 */
APR_DECLARE(void) apr_proc_other_child_check(void);

/** @deprecated @see apr_proc_other_child_alert
 * @bug This function's name had nothing to do with it's purpose
 */
APR_DECLARE(apr_status_t) apr_proc_other_child_read(apr_proc_t *proc, int status);


/** 
 * Terminate a process.
 * @param proc The process to terminate.
 * @param sig How to kill the process.
 */
APR_DECLARE(apr_status_t) apr_proc_kill(apr_proc_t *proc, int sig);

/**
 * Register a process to be killed when a pool dies.
 * @param a The pool to use to define the processes lifetime 
 * @param proc The process to register
 * @param how How to kill the process, one of:
 * <PRE>
 *         APR_KILL_NEVER         -- process is never sent any signals
 *         APR_KILL_ALWAYS        -- process is sent SIGKILL on apr_pool_t cleanup
 *         APR_KILL_AFTER_TIMEOUT -- SIGTERM, wait 3 seconds, SIGKILL
 *         APR_JUST_WAIT          -- wait forever for the process to complete
 *         APR_KILL_ONLY_ONCE     -- send SIGTERM and then wait
 * </PRE>
 */
APR_DECLARE(void) apr_pool_note_subprocess(apr_pool_t *a, apr_proc_t *proc,
                                           apr_kill_conditions_e how);

#if APR_HAS_THREADS 

#if (APR_HAVE_SIGWAIT || APR_HAVE_SIGSUSPEND) && !defined(OS2)

/**
 * Setup the process for a single thread to be used for all signal handling.
 * @warning This must be called before any threads are created
 */
APR_DECLARE(apr_status_t) apr_setup_signal_thread(void);

/**
 * Make the current thread listen for signals.  This thread will loop
 * forever, calling a provided function whenever it receives a signal.  That
 * functions should return 1 if the signal has been handled, 0 otherwise.
 * @param signal_handler The function to call when a signal is received
 * apr_status_t apr_signal_thread((int)(*signal_handler)(int signum))
 */
APR_DECLARE(apr_status_t) apr_signal_thread(int(*signal_handler)(int signum));

#endif /* (APR_HAVE_SIGWAIT || APR_HAVE_SIGSUSPEND) && !defined(OS2) */

/**
 * Get the child-pool used by the thread from the thread info.
 * @return apr_pool_t the pool
 */
APR_POOL_DECLARE_ACCESSOR(thread);

#endif /* APR_HAS_THREADS */

/** @} */

#ifdef __cplusplus
}
#endif

#endif  /* ! APR_THREAD_PROC_H */