global/pidfile: do not start two daemons with a single pid-file

add functions named pidfile_open and pidfile_verify to avoid starting two daemons by a single pid-file

Fixes: #13422
Signed-off-by: shun song <song.shun3@zte.com.cn>
(cherry picked from commit f2c0ef40fd674fecc6e3e97cd6155b976e6759b4)

diff --git a/src/global/global_init.cc b/src/global/global_init.cc
index 3464b0aff534fa7f5e299c87f731d384d2505cc5..6be6b2e717e580af798779c61b1cf65e7008e5ee 100644 (file)
--- a/src/global/global_init.cc
+++ b/src/global/global_init.cc
@@ -160,14 +160,19 @@ int global_init_prefork(CephContext *cct, int flags)
 {
   if (g_code_env != CODE_ENVIRONMENT_DAEMON)
     return -1;
+
   const md_config_t *conf = cct->_conf;
   if (!conf->daemonize) {
+
+    if (pidfile_open(g_conf) < 0) {
+      exit(1);
+    }
+
     if (atexit(pidfile_remove_void)) {
       derr << "global_init_daemonize: failed to set pidfile_remove function "
           << "to run at exit." << dendl;
     }
-
-    pidfile_write(g_conf);
+    pidfile_write();
 
     return -1;
   }
@@ -190,7 +195,7 @@ void global_init_daemonize(CephContext *cct, int flags)
         << cpp_strerror(ret) << dendl;
     exit(1);
   }
-
+ 
   global_init_postfork_start(cct);
   global_init_postfork_finish(cct, flags);
 }
@@ -200,6 +205,10 @@ void global_init_postfork_start(CephContext *cct)
   // restart log thread
   g_ceph_context->_log->start();
 
+  if (pidfile_open(g_conf) < 0) {
+    exit(1);
+  }
+
   if (atexit(pidfile_remove_void)) {
     derr << "global_init_daemonize: failed to set pidfile_remove function "
         << "to run at exit." << dendl;
@@ -228,7 +237,7 @@ void global_init_postfork_start(CephContext *cct)
     exit(1);
   }
 
-  pidfile_write(g_conf);
+  pidfile_write();
 }
 
 void global_init_postfork_finish(CephContext *cct, int flags)

diff --git a/src/global/pidfile.cc b/src/global/pidfile.cc
index 3b8962a0ea34b7cb48f3f31ecbec2fd0aef22aa6..c9452647ae99bc25c7b8916282902c2a5e64c6a9 100644 (file)
--- a/src/global/pidfile.cc
+++ b/src/global/pidfile.cc
@@ -31,68 +31,144 @@
 
 #define dout_prefix *_dout
 
-static char pid_file[PATH_MAX] = "";
+struct pidfh {
+  int pf_fd;
+  char pf_path[PATH_MAX + 1];
+  dev_t pf_dev;
+  ino_t pf_ino;
+ 
+  pidfh() : pf_fd(-1), pf_dev(0), pf_ino(0) {
+    memset(pf_path, 0, sizeof(pf_path));
+  }
+  
+  void close() {
+    pf_fd = -1;
+    pf_path[0] = '\0';
+    pf_dev = 0;
+    pf_ino = 0;
+  }
+};
+static pidfh pfh;
 
-int pidfile_write(const md_config_t *conf)
-{
-  int ret, fd;
+static int pidfile_verify() {
+  struct stat st;
 
-  if (conf->pid_file.empty()) {
-    return pidfile_remove();
+  if (pfh.pf_fd == -1) {
+    return -EINVAL;
+  }
+  /*
+   * Check remembered descriptor
+   */ 
+  if (fstat(pfh.pf_fd, &st) == -1) {
+    return -errno;
   }
-  snprintf(pid_file, PATH_MAX, "%s", conf->pid_file.c_str());
 
-  fd = TEMP_FAILURE_RETRY(::open(pid_file,
-                                O_CREAT|O_TRUNC|O_WRONLY, 0644));
-  if (fd < 0) {
-    int err = errno;
-    derr << "write_pid_file: failed to open pid file '"
-        << pid_file << "': " << cpp_strerror(err) << dendl;
-    return err;
+  if (st.st_dev != pfh.pf_dev || st.st_ino != pfh.pf_ino) {
+    return -ESTALE;
+  }
+  return 0;
+}
+
+int pidfile_write() 
+{
+  if (!pfh.pf_path[0]) {
+    return 0;
   }
 
-  char buf[20];
+  int ret;
+  if ((ret = pidfile_verify()) < 0) {
+    return ret;
+  }
+  
+  char buf[32];
   int len = snprintf(buf, sizeof(buf), "%d\n", getpid());
-  ret = safe_write(fd, buf, len);
+  ret = safe_write(pfh.pf_fd, buf, len);
   if (ret < 0) {
     derr << "write_pid_file: failed to write to pid file '"
-        << pid_file << "': " << cpp_strerror(ret) << dendl;
-    VOID_TEMP_FAILURE_RETRY(::close(fd));
+        << pfh.pf_path << "': " << cpp_strerror(ret) << dendl;
+    pfh.close(); 
     return ret;
   }
-  if (TEMP_FAILURE_RETRY(::close(fd))) {
-    ret = errno;
-    derr << "SimpleMessenger::write_pid_file: failed to close to pid file '"
-        << pid_file << "': " << cpp_strerror(ret) << dendl;
-    return -ret;
-  }
 
   return 0;
 }
 
-int pidfile_remove(void)
+int pidfile_remove()
 {
-  if (!pid_file[0])
+  if (!pfh.pf_path[0]) {
     return 0;
+  }
+
+  int ret;
+  if ((ret = pidfile_verify()) < 0) {
+    if (pfh.pf_fd != -1) {
+      ::close(pfh.pf_fd);
+    }
+    return ret;
+  }
 
   // only remove it if it has OUR pid in it!
-  int fd = TEMP_FAILURE_RETRY(::open(pid_file, O_RDONLY));
-  if (fd < 0)
-    return -errno;
   char buf[32];
   memset(buf, 0, sizeof(buf));
-  ssize_t res = safe_read(fd, buf, sizeof(buf));
-  VOID_TEMP_FAILURE_RETRY(::close(fd));
-  if (res < 0)
+  ssize_t res = safe_read(pfh.pf_fd, buf, sizeof(buf));
+  if (pfh.pf_fd != -1) {
+    ::close(pfh.pf_fd);
+  }
+
+  if (res < 0) {
     return res;
+  }
+  
   int a = atoi(buf);
-  if (a != getpid())
+  if (a != getpid()) {
     return -EDOM;
-
-  res = ::unlink(pid_file);
-  if (res)
+  }
+  res = ::unlink(pfh.pf_path);
+  if (res) {
     return res;
+  }
+  pfh.close();
+  return 0;
+}
+
+int pidfile_open(const md_config_t *conf) 
+{
+  if (conf->pid_file.empty()) {
+    return 0;
+  }
+  int len = snprintf(pfh.pf_path, sizeof(pfh.pf_path),
+                    "%s", conf->pid_file.c_str());
+
+  if (len >= (int)sizeof(pfh.pf_path)) { 
+    return -ENAMETOOLONG;
+  }
 
-  pid_file[0] = '\0';
+  int fd;
+  fd = ::open(pfh.pf_path, O_CREAT|O_WRONLY, 0644);
+  if (fd < 0) {
+    int err = errno;
+    derr << "write_pid_file: failed to open pid file '"
+         << pfh.pf_path << "': " << cpp_strerror(err) << dendl;
+    pfh.close();
+    return -errno;
+  }
+  struct stat st;   
+  if (fstat(fd, &st) == -1) {
+    close(fd);
+    pfh.close();  
+    return -errno;
+  }
+  pfh.pf_fd = fd;
+  pfh.pf_dev = st.st_dev;
+  pfh.pf_ino = st.st_ino;
+  
+  struct flock l = { F_WRLCK, SEEK_SET, 0, 0, 0 };
+  int r = ::fcntl(pfh.pf_fd, F_SETLK, &l);
+  if (r < 0) {
+    derr << "failed to lock pidfile - " << pfh.pf_path << ". is there another process in use?" << dendl;
+    close(pfh.pf_fd);
+    pfh.close();
+    return -errno;
+  }
   return 0;
 }

diff --git a/src/global/pidfile.h b/src/global/pidfile.h
index 6b60a5a16b50f489ecbcb9704370c452af39fedb..49ea5416ac1488b31789db7c4b041830d3f3570b 100644 (file)
--- a/src/global/pidfile.h
+++ b/src/global/pidfile.h
@@ -19,10 +19,13 @@ struct md_config_t;
 
 // Write a pidfile with the current pid, using the configuration in the
 // provided conf structure.
-int pidfile_write(const md_config_t *conf);
+int pidfile_write();
 
 // Remove the pid file that was previously written by pidfile_write.
 // This is safe to call in a signal handler context.
-int pidfile_remove(void);
+int pidfile_remove();
+
+// test whether the pid_file is being used by another process
+int pidfile_open(const md_config_t *conf);
 
 #endif