Filesystem: Reference counting for locations

 o A new data structure rtems_filesystem_global_location_t was
   introduced to be used for
    o the mount point location in the mount table entry,
    o the file system root location in the mount table entry,
    o the root directory location in the user environment, and
    o the current directory location in the user environment.
   During the path evaluation global start locations are obtained to
   ensure that the current file system instance will be not unmounted in
   the meantime.
 o The user environment uses now reference counting and is protected
   from concurrent access.
 o The path evaluation process was completely rewritten and simplified.
   The IMFS, RFS, NFS, and DOSFS use now a generic path evaluation
   method.  Recursive calls in the path evaluation have been replaced
   with iteration to avoid stack overflows.  Only the evaluation of
   symbolic links is recursive.  No dynamic memory allocations and
   intermediate buffers are used in the high level path evaluation.  No
   global locks are held during the file system instance specific path
   evaluation process.
 o Recursive symbolic link evaluation is now limited by
   RTEMS_FILESYSTEM_SYMLOOP_MAX.  Applications can retrieve this value
   via sysconf().
 o The device file system (devFS) uses now no global variables and
   allocation from the workspace.  Node names are allocated from the
   heap.
 o The upper layer lseek() performs now some parameter checks.
 o The upper layer ftruncate() performs now some parameter checks.
 o unmask() is now restricted to the RWX flags and protected from
   concurrent access.
 o The fchmod_h and rmnod_h file system node handlers are now a file
   system operation.
 o The unlink_h operation has been removed.  All nodes are now destroyed
   with the rmnod_h operation.
 o New lock_h, unlock_h, clonenod_h, and are_nodes_equal_h file system
   operations.
 o The path evaluation and file system operations are now protected by
   per file system instance lock and unlock operations.
 o Fix and test file descriptor duplicate in fcntl().
 o New test fstests/fsnofs01.

1 files changed, 141 insertions, 198 deletions

diff --git a/c/src/lib/libbsp/shared/umon/tfsDriver.c b/c/src/lib/libbsp/shared/umon/tfsDriver.c
index bf56e2a8b4..fcff017b94 100644
--- a/c/src/lib/libbsp/shared/umon/tfsDriver.c
+++ b/c/src/lib/libbsp/shared/umon/tfsDriver.c
@@ -3,6 +3,9 @@
  *
  *  Initial release: Oct 1, 2004   by Ed Sutter
  *
+ *  Modifications to support reference counting in the file system are
+ *  Copyright (c) 2012 embedded brains GmbH.
+ *
  *  This code was derived from the tftpDriver.c code written by
  *  W. Eric Norum, which was apparently derived from the IMFS driver.
  *
@@ -69,79 +72,31 @@ struct tfdinfo {
  */
 char TFS_PATHNAME_PREFIX[128];
 
-/*
- * Root node_access value
- * By using the address of a local static variable
- * we ensure a unique value for this identifier.
- */
-#define ROOT_NODE_ACCESS    (&tfs_mutex)
-
-/* Number of streams open at the same time
- */
-static rtems_id tfs_mutex;
-
-extern rtems_filesystem_operations_table  rtems_tfs_ops;
-extern rtems_filesystem_file_handlers_r   rtems_tfs_handlers;
-
-/* Direct copy from the IMFS.  Look at this.
- */
+static const rtems_filesystem_operations_table  rtems_tfs_ops;
+static const rtems_filesystem_file_handlers_r   rtems_tfs_handlers;
 
-rtems_filesystem_limits_and_options_t rtems_tfs_limits_and_options = {
-  5,   /* link_max */
-  6,   /* max_canon */
-  7,   /* max_input */
-  255, /* name_max */
-  255, /* path_max */
-  2,   /* pipe_buf */
-  1,   /* posix_async_io */
-  2,   /* posix_chown_restrictions */
-  3,   /* posix_no_trunc */
-  4,   /* posix_prio_io */
-  5,   /* posix_sync_io */
-  6    /* posix_vdisable */
-};
+static bool rtems_tfs_is_directory(
+    const char *path,
+    size_t pathlen
+)
+{
+    return path [pathlen - 1] == '/';
+}
 
 static int rtems_tfs_mount_me(
   rtems_filesystem_mount_table_entry_t *mt_entry,
   const void                           *data
 )
 {
-  rtems_status_code  sc;
-
-  mt_entry->mt_fs_root.handlers = &rtems_tfs_handlers;
-  mt_entry->mt_fs_root.ops      = &rtems_tfs_ops;
-
-  /* We have no TFS specific data to maintain.  This filesystem
-   * may only be mounted once. And we maintain no real filesystem
-   * nodes, so there is no real root.
-   */
-
-  mt_entry->fs_info                = NULL;
-  mt_entry->mt_fs_root.node_access = ROOT_NODE_ACCESS;
+  char *root_path = strdup("/");
 
-  /* These need to be looked at for full POSIX semantics.
-   */
-
-  mt_entry->pathconf_limits_and_options = rtems_tfs_limits_and_options;
-
-
-  /*  Now allocate a semaphore for mutual exclusion.
-   *  NOTE:  This could be in an fsinfo for this filesystem type.
-   */
-
-  sc = rtems_semaphore_create (
-    rtems_build_name('U', 'M', 'O', 'N'),
-    1,
-    RTEMS_FIFO |
-      RTEMS_BINARY_SEMAPHORE |
-      RTEMS_NO_INHERIT_PRIORITY |
-      RTEMS_NO_PRIORITY_CEILING |
-      RTEMS_LOCAL,
-    0,
-    &tfs_mutex);
+  if (root_path == NULL) {
+    rtems_set_errno_and_return_minus_one(ENOMEM);
+  }
 
-  if (sc != RTEMS_SUCCESSFUL)
-    rtems_set_errno_and_return_minus_one( ENOMEM );
+  mt_entry->mt_fs_root->location.handlers = &rtems_tfs_handlers;
+  mt_entry->mt_fs_root->location.ops = &rtems_tfs_ops;
+  mt_entry->mt_fs_root->location.node_access = root_path;
 
   return 0;
 }
@@ -180,16 +135,6 @@ int rtems_initialize_tfs_filesystem(
   return(status);
 }
 
-static int rtems_tfs_evaluate_for_make(
-  const char                         *path,
-  rtems_filesystem_location_info_t   *pathloc,
-  const char                        **name
-)
-{
-  pathloc->node_access = NULL;
-  rtems_set_errno_and_return_minus_one( EIO );
-}
-
 /*
  * Convert a path to canonical form
  */
@@ -242,53 +187,41 @@ static void fixPath(char *path)
   *outp = '\0';
 }
 
-static int rtems_tfs_eval_path(
-  const char                        *pathname,
-  size_t                             pathnamelen,
-  int                                flags,
-  rtems_filesystem_location_info_t  *pathloc
-)
+static void rtems_tfs_eval_path(rtems_filesystem_eval_path_context_t *self)
 {
-  pathloc->handlers    = &rtems_tfs_handlers;
-
-  /*
-   * Hack to provide the illusion of directories inside the TFS file system.
-   * Paths ending in a / are assumed to be directories.
-   */
-  if (pathname[strlen(pathname)-1] == '/') {
-    int isRelative = (pathloc->node_access != ROOT_NODE_ACCESS);
-    char *cp;
-
-    /*
-     * Reject attempts to open() directories
-     */
-    if (flags & RTEMS_LIBIO_PERMS_RDWR)
-      rtems_set_errno_and_return_minus_one( EISDIR );
-    if (isRelative) {
-      cp = malloc (strlen(pathloc->node_access)+strlen(pathname)+1);
-      if (cp == NULL)
-        rtems_set_errno_and_return_minus_one( ENOMEM );
-      strcpy (cp, pathloc->node_access);
-      strcat (cp, pathname);
+  int eval_flags = rtems_filesystem_eval_path_get_flags(self);
+
+  if ((eval_flags & RTEMS_LIBIO_MAKE) == 0) {
+    int rw = RTEMS_LIBIO_PERMS_READ | RTEMS_LIBIO_PERMS_WRITE;
+
+    if ((eval_flags & rw) != rw) {
+      rtems_filesystem_location_info_t *currentloc =
+        rtems_filesystem_eval_path_get_currentloc(self);
+      char *current = currentloc->node_access;
+      size_t currentlen = strlen(current);
+      const char *path = rtems_filesystem_eval_path_get_path(self);
+      size_t pathlen = rtems_filesystem_eval_path_get_pathlen(self);
+      size_t len = currentlen + pathlen;
+
+      rtems_filesystem_eval_path_clear_path(self);
+
+      current = realloc(current, len + 1);
+      if (current != NULL) {
+        memcpy(current + currentlen, path, pathlen);
+        current [len] = '\0';
+        if (!rtems_tfs_is_directory(current, len)) {
+          fixPath (current);
+        }
+        currentloc->node_access = current;
+      } else {
+        rtems_filesystem_eval_path_error(self, ENOMEM);
+      }
     } else {
-      cp = strdup (pathname);
-      if (cp == NULL)
-        rtems_set_errno_and_return_minus_one( ENOMEM );
+      rtems_filesystem_eval_path_error(self, EINVAL);
     }
-    fixPath (cp);
-    pathloc->node_access = cp;
-    return 0;
+  } else {
+    rtems_filesystem_eval_path_error(self, EIO);
   }
-  if (pathloc->node_access != ROOT_NODE_ACCESS)
-    pathloc->node_access = 0;
-
-  /*
-   * Reject it if it's not read-only or write-only.
-   */
-  flags &= RTEMS_LIBIO_PERMS_READ | RTEMS_LIBIO_PERMS_WRITE;
-  if ((flags != RTEMS_LIBIO_PERMS_READ) && (flags != RTEMS_LIBIO_PERMS_WRITE) )
-    rtems_set_errno_and_return_minus_one( EINVAL );
-  return 0;
 }
 
 /*
@@ -310,8 +243,8 @@ static int rtems_tfs_eval_path(
 static int rtems_tfs_open_worker(
   rtems_libio_t *iop,
   char          *path,
-  uint32_t       flags,
-  uint32_t       mode
+  int            oflag,
+  mode_t         mode
 )
 {
   static int beenhere = 0;
@@ -321,7 +254,7 @@ static int rtems_tfs_open_worker(
   char *buf, *fstr, *istr, *bstr, pathcopy[TFSNAMESIZE*3+1];
 
   if (RTEMS_TFS_DEBUG)
-    printk("_open_r(%s,0x%" PRIx32 ",0x%" PRIx32 ")\n",path,flags,mode);
+    printk("_open_r(%s,0x%" PRIx32 ",0x%" PRIx32 ")\n",path,oflag,mode);
 
   if (!beenhere) {
     newlib_tfdlock();
@@ -371,7 +304,7 @@ static int rtems_tfs_open_worker(
 
   /* If O_EXCL and O_CREAT are set, then fail if the file exists...
    */
-  if ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL)) {
+  if ((oflag & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL)) {
     if (mon_tfsstat((char *)pathcopy)) {
       return(EEXIST);
     }
@@ -384,7 +317,7 @@ static int rtems_tfs_open_worker(
    * O_WRONLY | O_CREAT       Create if it doesn't exist
    * O_WRONLY | O_CREAT | O_EXCL   Fail if file exists
    */
-  switch(flags & O_ACCMODE) {
+  switch(oflag & O_ACCMODE) {
     case O_RDONLY:
       flagmode = TFS_RDONLY;
       break;
@@ -405,7 +338,7 @@ static int rtems_tfs_open_worker(
       flagmode = TFS_CREATE|TFS_APPEND;
       break;
     default:
-      printk("_open_r(): flag 0x%" PRIx32 " not supported\n",flags);
+      printk("_open_r(): flag 0x%i not supported\n",oflag);
       return(ENOTSUP);
   }
 
@@ -489,41 +422,27 @@ static int rtems_tfs_open_worker(
 static int rtems_tfs_open(
   rtems_libio_t *iop,
   const char    *new_name,
-  uint32_t       flags,
-  uint32_t       mode
+  int            oflag,
+  mode_t         mode
 )
 {
   char *full_path_name;
-  char *s1;
   int err;
 
+  full_path_name = iop->pathinfo.node_access;
+
   if (RTEMS_TFS_DEBUG)
-    printk("rtems_tfs_open(%s)\n",new_name);
+    printk("rtems_tfs_open(%s)\n",full_path_name);
 
-  /*
-   * Tack the `current directory' on to relative paths.
-   * We know that the current directory ends in a / character.
-   */
-  if (*new_name == '/') {
-    /*
-     * Skip the TFS filesystem prefix.
-     */
-    int len = strlen (TFS_PATHNAME_PREFIX);
-    if (strncmp (new_name, TFS_PATHNAME_PREFIX, len))
-      return ENOENT;
-    new_name += len;
-    s1 = "";
-  } else {
-    s1 = rtems_filesystem_current.node_access;
+  if (rtems_tfs_is_directory(full_path_name, strlen(full_path_name))) {
+    rtems_set_errno_and_return_minus_one (ENOTSUP);
   }
-  full_path_name = malloc (strlen (s1) + strlen (new_name) + 1);
-  if (full_path_name == NULL)
-    return ENOMEM;
-  strcpy (full_path_name, s1);
-  strcat (full_path_name, new_name);
-  fixPath (full_path_name);
-  err = rtems_tfs_open_worker (iop, full_path_name, flags, mode);
-  free (full_path_name);
+
+  err = rtems_tfs_open_worker (iop, full_path_name, oflag, mode);
+  if (err != 0) {
+     rtems_set_errno_and_return_minus_one (err);
+  }
+
   return err;
 }
 
@@ -671,68 +590,92 @@ static int rtems_tfs_ioctl(
   void          *buf
 )
 {
-  int  fd, ret;
+  int ret;
 
-  fd = (int) iop->data0;
   ret = mon_tfsctrl(cmd,(long)buf,0);
-  return(-1);
+  if (ret != TFS_OKAY)
+    return(-1);
+
+  return(0);
 }
 
 static rtems_filesystem_node_types_t rtems_tfs_node_type(
-  rtems_filesystem_location_info_t *pathloc
+  const rtems_filesystem_location_info_t *loc
 )
 {
-  if ((pathloc->node_access == NULL) ||
-      (pathloc->node_access == ROOT_NODE_ACCESS))
-    return RTEMS_FILESYSTEM_MEMORY_FILE;
-  return RTEMS_FILESYSTEM_DIRECTORY;
-}
+  const char *path = loc->node_access;
+  size_t pathlen = strlen(path);
 
-static int rtems_tfs_free_node_info(
+  return rtems_tfs_is_directory(path, pathlen) ?
+    RTEMS_FILESYSTEM_DIRECTORY
+      : RTEMS_FILESYSTEM_MEMORY_FILE;
+}
 
-rtems_filesystem_location_info_t *pathloc)
+static int rtems_tfs_clone_node_info(
+  rtems_filesystem_location_info_t *loc
+)
 {
-  if (pathloc->node_access && (pathloc->node_access != ROOT_NODE_ACCESS)) {
-    free (pathloc->node_access);
-    pathloc->node_access = NULL;
+  int rv = 0;
+
+  loc->node_access = strdup(loc->node_access);
+
+  if (loc->node_access == NULL) {
+    errno = ENOMEM;
+    rv = -1;
   }
-  return 0;
+
+  return rv;
 }
 
+static void rtems_tfs_free_node_info(
+  const rtems_filesystem_location_info_t *loc
+)
+{
+  free(loc->node_access);
+}
+
+static bool rtems_tfs_are_nodes_equal(
+  const rtems_filesystem_location_info_t *a,
+  const rtems_filesystem_location_info_t *b
+)
+{
+  return strcmp(a->node_access, b->node_access) == 0;
+}
 
-rtems_filesystem_operations_table  rtems_tfs_ops = {
-  rtems_tfs_eval_path,                    /* eval_path */
-  rtems_tfs_evaluate_for_make,            /* evaluate_for_make */
-  rtems_filesystem_default_link,          /* link */
-  rtems_filesystem_default_unlink,        /* unlink */
-  rtems_tfs_node_type,                    /* node_type */
-  rtems_filesystem_default_mknod,         /* mknod */
-  rtems_filesystem_default_chown,         /* chown */
-  rtems_tfs_free_node_info,               /* freenodinfo */
-  rtems_filesystem_default_mount,         /* mount */
-  rtems_tfs_mount_me,                     /* initialize */
-  rtems_filesystem_default_unmount,       /* unmount */
-  rtems_filesystem_default_fsunmount,     /* fsunmount */
-  rtems_filesystem_default_utime,         /* utime */
-  rtems_filesystem_default_evaluate_link, /* evaluate_link */
-  rtems_filesystem_default_symlink,       /* symlink */
-  rtems_filesystem_default_readlink,      /* readlin */
-  rtems_filesystem_default_rename,        /* rename */
-  rtems_filesystem_default_statvfs        /* statvfs */
+static const rtems_filesystem_operations_table  rtems_tfs_ops = {
+  .lock_h = rtems_filesystem_default_lock,
+  .unlock_h = rtems_filesystem_default_unlock,
+  .eval_path_h = rtems_tfs_eval_path,
+  .link_h = rtems_filesystem_default_link,
+  .are_nodes_equal_h = rtems_tfs_are_nodes_equal,
+  .node_type_h = rtems_tfs_node_type,
+  .mknod_h = rtems_filesystem_default_mknod,
+  .rmnod_h = rtems_filesystem_default_rmnod,
+  .fchmod_h = rtems_filesystem_default_fchmod,
+  .chown_h = rtems_filesystem_default_chown,
+  .clonenod_h = rtems_tfs_clone_node_info,
+  .freenod_h = rtems_tfs_free_node_info,
+  .mount_h = rtems_filesystem_default_mount,
+  .fsmount_me_h = rtems_tfs_mount_me,
+  .unmount_h = rtems_filesystem_default_unmount,
+  .fsunmount_me_h = rtems_filesystem_default_fsunmount,
+  .utime_h = rtems_filesystem_default_utime,
+  .symlink_h = rtems_filesystem_default_symlink,
+  .readlink_h = rtems_filesystem_default_readlink,
+  .rename_h = rtems_filesystem_default_rename,
+  .statvfs_h = rtems_filesystem_default_statvfs
 };
 
-rtems_filesystem_file_handlers_r rtems_tfs_handlers = {
-  rtems_tfs_open,                     /* open */
-  rtems_tfs_close,                    /* close */
-  rtems_tfs_read,                     /* read */
-  rtems_tfs_write,                    /* write */
-  rtems_tfs_ioctl,                    /* ioctl */
-  rtems_tfs_lseek,                    /* lseek */
-  rtems_filesystem_default_fstat,     /* fstat */
-  rtems_filesystem_default_fchmod,    /* fchmod */
-  rtems_tfs_ftruncate,                /* ftruncate */
-  rtems_filesystem_default_fsync,     /* fsync */
-  rtems_filesystem_default_fdatasync, /* fdatasync */
-  rtems_filesystem_default_fcntl,     /* fcntl */
-  rtems_filesystem_default_rmnod      /* rmnod */
+static const rtems_filesystem_file_handlers_r rtems_tfs_handlers = {
+  .open_h = rtems_tfs_open,
+  .close_h = rtems_tfs_close,
+  .read_h = rtems_tfs_read,
+  .write_h = rtems_tfs_write,
+  .ioctl_h = rtems_tfs_ioctl,
+  .lseek_h = rtems_tfs_lseek,
+  .fstat_h = rtems_filesystem_default_fstat,
+  .ftruncate_h = rtems_tfs_ftruncate,
+  .fsync_h = rtems_filesystem_default_fsync,
+  .fdatasync_h = rtems_filesystem_default_fdatasync,
+  .fcntl_h = rtems_filesystem_default_fcntl
 };