Fixed "changing binary" when reaper is not init.

On some systems, it's possible that reaper of orphaned processes is
set to something other than "init" process.  On such systems, the
changing binary procedure did not work.

The fix is to check if PPID has changed, instead of assuming it's
always 1 for orphaned processes.

src/core/nginx.c

@@ -228,6 +228,7 @@ main(int argc, char *const *argv)
 #endif
 
     ngx_pid = ngx_getpid();
+    ngx_parent = ngx_getppid();
 
     log = ngx_log_init(ngx_prefix);
     if (log == NULL) {

src/os/unix/ngx_daemon.c

@@ -26,6 +26,7 @@ ngx_daemon(ngx_log_t *log)
         exit(0);
     }
 
+    ngx_parent = ngx_pid;
     ngx_pid = ngx_getpid();
 
     if (setsid() == -1) {

src/os/unix/ngx_process.c

@@ -194,6 +194,7 @@ ngx_spawn_process(ngx_cycle_t *cycle, ngx_spawn_proc_pt proc, void *data,
         return NGX_INVALID_PID;
 
     case 0:
+        ngx_parent = ngx_pid;
         ngx_pid = ngx_getpid();
         proc(cycle, data);
         break;
@@ -371,12 +372,12 @@ ngx_signal_handler(int signo, siginfo_t *siginfo, void *ucontext)
             break;
 
         case ngx_signal_value(NGX_CHANGEBIN_SIGNAL):
-            if (getppid() > 1 || ngx_new_binary > 0) {
+            if (ngx_getppid() == ngx_parent || ngx_new_binary > 0) {
 
                 /*
                  * Ignore the signal in the new binary if its parent is
-                 * not the init process, i.e. the old binary's process
+                 * not changed, i.e. the old binary's process is still
-                 * is still running.  Or ignore the signal in the old binary's
+                 * running.  Or ignore the signal in the old binary's
                  * process if the new binary's process is already running.
                  */
 

src/os/unix/ngx_process.h

@@ -54,6 +54,7 @@ typedef struct {
 
 
 #define ngx_getpid   getpid
+#define ngx_getppid  getppid
 
 #ifndef ngx_log_pid
 #define ngx_log_pid  ngx_pid
@@ -79,6 +80,7 @@ extern char         **ngx_argv;
 extern char         **ngx_os_argv;
 
 extern ngx_pid_t      ngx_pid;
+extern ngx_pid_t      ngx_parent;
 extern ngx_socket_t   ngx_channel;
 extern ngx_int_t      ngx_process_slot;
 extern ngx_int_t      ngx_last_process;

src/os/unix/ngx_process_cycle.c

@@ -31,6 +31,7 @@ static void ngx_cache_loader_process_handler(ngx_event_t *ev);
 ngx_uint_t    ngx_process;
 ngx_uint_t    ngx_worker;
 ngx_pid_t     ngx_pid;
+ngx_pid_t     ngx_parent;
 
 sig_atomic_t  ngx_reap;
 sig_atomic_t  ngx_sigio;

src/os/win32/ngx_process.h

@@ -14,6 +14,7 @@ typedef DWORD               ngx_pid_t;
 
 
 #define ngx_getpid          GetCurrentProcessId
+#define ngx_getppid()       0
 #define ngx_log_pid         ngx_pid
 
 
@@ -73,6 +74,7 @@ extern ngx_int_t            ngx_last_process;
 extern ngx_process_t        ngx_processes[NGX_MAX_PROCESSES];
 
 extern ngx_pid_t            ngx_pid;
+extern ngx_pid_t            ngx_parent;
 
 
 #endif /* _NGX_PROCESS_H_INCLUDED_ */

src/os/win32/ngx_process_cycle.c

@@ -31,6 +31,7 @@ static ngx_thread_value_t __stdcall ngx_cache_loader_thread(void *data);
 ngx_uint_t     ngx_process;
 ngx_uint_t     ngx_worker;
 ngx_pid_t      ngx_pid;
+ngx_pid_t      ngx_parent;
 
 ngx_uint_t     ngx_inherited;
 ngx_pid_t      ngx_new_binary;