2003-01-03 Till Straumann <strauman@slac.stanford.edu>

* ChangeLog, base_fs.c, getpwent.c, privateenv.c
	Per PR303, Fix violation of node_access copy syemantics

cpukit/libcsupport/src/base_fs.c

@@ -49,6 +49,7 @@ void rtems_filesystem_initialize( void )
   int                                   status;
   rtems_filesystem_mount_table_entry_t *entry;
   rtems_filesystem_mount_table_t       *mt;
+  rtems_filesystem_location_info_t		loc;
   
   /*
    *  Set the default umask to "022".
@@ -75,8 +76,38 @@ void rtems_filesystem_initialize( void )
     rtems_fatal_error_occurred( 0xABCD0002 );
 
   rtems_filesystem_link_counts = 0;
+
+  /* setup the 'current' and 'root' directories
+   *
+   * NOTE: cloning the pathlocs is not strictly
+   *       necessary. Since we implicitely let
+   *       all threads that don't call
+   *       libio_set_private_env() share the same
+   *       (initial) 'root' and 'current' locs,
+   *       we (also implicitely) assume that the
+   *       root filesystem doesn't care about
+   *       reference counts.
+   *       I just inserted the code snippet below
+   *       to remind everybody of the fact by
+   *       making it more explicit...
+   *       Ideally, every thread would have to
+   *       call either share_private_env() or
+   *       set_private_env() - but then: that's
+   *       gonna hit performance.
+   *
+   *       Till Straumann, 10/25/2002
+   */
   rtems_filesystem_root        = entry->mt_fs_root;
-  rtems_filesystem_current     = rtems_filesystem_root;
+  /* Clone the root pathloc */
+  rtems_filesystem_evaluate_path("/", 0, &loc, 0);
+  rtems_filesystem_root        = loc;
+  /* One more clone for the current node */
+  rtems_filesystem_evaluate_path("/", 0, &loc, 0);
+  rtems_filesystem_current     = loc;
+
+  /* Note: the global_env's refcnt doesn't matter
+   * as the global env is never released
+   */
 
 
   /*

cpukit/libcsupport/src/getpwent.c

@@ -185,21 +185,17 @@ static int getpw_r(
 {
   FILE *fp;
   int match;
-  rtems_user_env_t * aux=rtems_current_user_env; /* save */
 
   init_etc_passwd_group();
-  rtems_current_user_env=&rtems_global_user_env; /* set root */
 
   if ((fp = fopen("/etc/passwd", "r")) == NULL) {
     errno = EINVAL;
-    rtems_current_user_env=aux; /* restore */
     return -1;
   }
   for(;;) {
     if (!scanpw(fp, pwd, buffer, bufsize)) {
       errno = EINVAL;
       fclose(fp);
-      rtems_current_user_env=aux; /* restore */
       return -1;
     }
     if (name) {
@@ -211,13 +207,11 @@ static int getpw_r(
     if (match) {
       fclose(fp);
       *result = pwd;
-      rtems_current_user_env=aux; /* restore */
       return 0;
     }
   }
   fclose(fp);
   errno = EINVAL;
-  rtems_current_user_env=aux; /* restore */
   return -1;
 }
 
@@ -276,14 +270,11 @@ struct passwd *getpwent()
 
 void setpwent(void)
 {
-  rtems_user_env_t * aux=rtems_current_user_env; /* save */
   init_etc_passwd_group();
-  rtems_current_user_env=&rtems_global_user_env; /* set root */
 
   if (passwd_fp != NULL)
     fclose(passwd_fp);
   passwd_fp = fopen("/etc/passwd", "r");
-  rtems_current_user_env=aux; /* restore */
 }
 
 void endpwent(void)
@@ -353,21 +344,17 @@ static int getgr_r(
 {
   FILE *fp;
   int match;
-  rtems_user_env_t * aux=rtems_current_user_env; /* save */
 
   init_etc_passwd_group();
-  rtems_current_user_env=&rtems_global_user_env; /* set root */
 
   if ((fp = fopen("/etc/group", "r")) == NULL) {
     errno = EINVAL;
-    rtems_current_user_env=aux; /* restore */
     return -1;
   }
   for(;;) {
     if (!scangr(fp, grp, buffer, bufsize)) {
       errno = EINVAL;
       fclose(fp);
-      rtems_current_user_env=aux; /* restore */
       return -1;
     }
     if (name) {
@@ -379,13 +366,11 @@ static int getgr_r(
     if (match) {
       fclose(fp);
       *result = grp;
-      rtems_current_user_env=aux; /* restore */
       return 0;
     }
   }
   fclose(fp);
   errno = EINVAL;
-  rtems_current_user_env=aux; /* restore */
   return -1;
 }
 
@@ -444,14 +429,11 @@ struct group *getgrent()
 
 void setgrent(void)
 {
-  rtems_user_env_t * aux=rtems_current_user_env; /* save */
   init_etc_passwd_group();
-  rtems_current_user_env=&rtems_global_user_env; /* set root */
 
   if (group_fp != NULL)
     fclose(group_fp);
   group_fp = fopen("/etc/group", "r");
-  rtems_current_user_env=aux; /* restore */
 }
 
 void endgrent(void)

cpukit/libcsupport/src/privateenv.c

@@ -23,25 +23,75 @@
 #include <rtems/libio.h>
 #include <rtems/libio_.h>
 
+extern Chain_Control rtems_filesystem_mount_table_control;
+
+#define THE_ROOT_FS_LOC \
+	(((rtems_filesystem_mount_table_entry_t*)\
+	   rtems_filesystem_mount_table_control.first)->mt_fs_root)
+
+/* cleanup a user environment
+ * NOTE: this must be called with
+ *       thread dispatching disabled!
+ */
+static void
+free_user_env(rtems_user_env_t *env)
+{
+	if (env != &rtems_global_user_env 
+#ifdef HAVE_USERENV_REFCNT
+		&& --env->refcnt <= 0
+#endif
+		) {
+		rtems_filesystem_freenode( &env->current_directory);
+		rtems_filesystem_freenode( &env->root_directory);
+		free(env);
+	}
+}
+
 rtems_status_code rtems_libio_set_private_env(void) {
-  rtems_status_code sc;
-  rtems_id          task_id;
+  rtems_status_code 					sc;
+  rtems_id          					task_id;
+  rtems_filesystem_location_info_t		loc;
 
   sc=rtems_task_ident(RTEMS_SELF,0,&task_id);
   if (sc != RTEMS_SUCCESSFUL) return sc;
 
   /* Only for the first time a malloc is necesary */
-  if (rtems_current_user_env==&rtems_global_user_env) { 
-   sc = rtems_task_variable_add(RTEMS_SELF,(void*)&rtems_current_user_env,free);
-   if (sc != RTEMS_SUCCESSFUL) return sc;
-   rtems_current_user_env = malloc(sizeof(rtems_user_env_t));
-   if (!rtems_current_user_env)
+  if (rtems_current_user_env==&rtems_global_user_env) {
+   rtems_user_env_t	*tmp = malloc(sizeof(rtems_user_env_t));
+   if (!tmp)
      return RTEMS_NO_MEMORY;
+
+#ifdef HAVE_USERENV_REFCNT
+   tmp->refcnt = 1;
+#endif
+
+   sc = rtems_task_variable_add(RTEMS_SELF,(void*)&rtems_current_user_env,free_user_env);
+   if (sc != RTEMS_SUCCESSFUL) {
+	 /* don't use free_user_env because the pathlocs are
+	  * not initialized yet
+	  */
+     free(tmp);
+     return sc;
+   }
+   rtems_current_user_env = tmp;
   }; 
 
-  /* the side effect desired . chroot("/") */
   *rtems_current_user_env = rtems_global_user_env; /* get the global values*/
   rtems_current_user_env->task_id=task_id;         /* mark the local values*/
+  
+  /* get a clean root */
+  rtems_filesystem_root    = THE_ROOT_FS_LOC;
+
+  /* Clone the pathlocs. In contrast to most other
+   * code we must _not_ free the original locs because
+   * what we are trying to do here is forking off
+   * clones.
+   */
+
+  rtems_filesystem_evaluate_path("/", 0, &loc, 0);
+  rtems_filesystem_root    = loc;
+  rtems_filesystem_evaluate_path("/", 0, &loc, 0);
+  rtems_filesystem_current = loc;
 
   return RTEMS_SUCCESSFUL;
 }
@@ -51,6 +101,21 @@ rtems_status_code rtems_libio_set_private_env(void) {
  *   Task_id (remote) and RTEMS_SELF(current).
  */
 
+/* NOTE:
+ *
+ * THIS CODE HAS NO PROTECTION IMPLEMENTED
+ *
+ * Tasks who wish to share their environments must
+ *
+ *  a) assert that no participants are concurrently
+ *     executing
+ *     libio_share_private_env() and/or libio_set_private_env()
+ *
+ *  b) mutex access to rtems_filesystem_current, rtems_filesytem_root
+ *     while changing any of those (chdir(), chroot()).
+ */
+
+#ifndef HAVE_USERENV_REFCNT
 rtems_status_code rtems_libio_share_private_env(rtems_id task_id) {
   rtems_status_code  sc;
   rtems_user_env_t * shared_user_env;
@@ -61,21 +126,36 @@ rtems_status_code rtems_libio_share_private_env(rtems_id task_id) {
 
   if (rtems_current_user_env->task_id==current_task_id) {
    /* kill the current user env & task_var*/	  
-   free(rtems_current_user_env);	  
+	rtems_user_env_t 	*tmp = rtems_current_user_env;
    sc = rtems_task_variable_delete(RTEMS_SELF,(void*)&rtems_current_user_env);
    if (sc != RTEMS_SUCCESSFUL) return sc;
+   free_user_env(tmp);	  
   };
 
+  /* AT THIS POINT, rtems_current_user_env is DANGLING */
+
   sc = rtems_task_variable_get(task_id,(void*)&rtems_current_user_env,
 		                       (void*)&shared_user_env       );
-  if (sc != RTEMS_SUCCESSFUL) return sc;
+  if (sc != RTEMS_SUCCESSFUL)
+    goto bailout;
 
-  /* don't free(NULL'ed) at the task_delete. It is a shared var... */	   
-  sc = rtems_task_variable_add(RTEMS_SELF,(void*)&rtems_current_user_env,NULL);
-  if (sc != RTEMS_SUCCESSFUL) return sc;
+  sc = rtems_task_variable_add(RTEMS_SELF,(void*)&rtems_current_user_env,free_user_env);
+  if (sc != RTEMS_SUCCESSFUL)
+    goto bailout;
   
   /* the current_user_env is the same pointer that remote env */
   rtems_current_user_env = shared_user_env;
 
+  /* increase the reference count */
+#ifdef HAVE_USERENV_REFCNT
+  rtems_current_user_env->refcnt++;
+#endif
+
   return RTEMS_SUCCESSFUL;
+
+bailout:
+  /* fallback to the global env */
+  rtems_current_user_env = &rtems_global_user_env;
+  return sc;
 }
+#endif