Fix #456, improve filesystem type identification

Add a distinct type for FS_BASED entries, and an UNKNOWN value
for when a type is actually not yet identified.

This can be used to identify the FS type first at the shared
layer, then in the implementation layer as a fallback option
if not identifiable in the shared layer.

Use the volume name prefix "RAM" as a hint that the volume
is supposed to be a VOLATILE disk as opposed to a normal disk.
This is done in shared layer so it applies to all OS types.

src/os/inc/osapi-os-filesys.h

@@ -763,7 +763,7 @@ int32 OS_rmdir (const char *path);
  * @brief Create a fixed mapping between an existing directory and a virtual OSAL mount point.
  *
  * This mimics the behavior of a "FS_BASED" entry in the VolumeTable but is registered
- * at runtime. It is intended to be called by the PSP/BSP prior to starting the OSAL.
+ * at runtime. It is intended to be called by the PSP/BSP prior to starting the application.
  *
  * @param[out] filesys_id An OSAL ID reflecting the file system
  * @param[in] phys_path The native system directory (an existing mount point)
@@ -781,10 +781,15 @@ int32 OS_FileSysAddFixedMap(uint32 *filesys_id, const char *phys_path,
  * Makes a file system on the target. Highly dependent on underlying OS and
  * dependent on OS volume table definition.
  *
+ * @note The "volname" parameter of RAM disks should always begin with the string "RAM",
+ * e.g. "RAMDISK" or "RAM0","RAM1", etc if multiple devices are created. The underlying
+ * implementation uses this to select the correct filesystem type/format, and this may
+ * also be used to differentiate between RAM disks and real physical disks.
+ *
  * @param[in] address The address at which to start the new disk. If address == 0
  * space will be allocated by the OS.
- * @param[in] devname The name of the "generic" drive
- * @param[in] volname The name of the volume (if needed, used on VxWorks)
+ * @param[in] devname The underlying kernel device to use, if applicable.
+ * @param[in] volname The name of the volume (see note)
  * @param[in] blocksize The size of a single block on the drive
  * @param[in] numblocks The number of blocks to allocate for the drive
  *
@@ -816,10 +821,15 @@ int32 OS_mount (const char *devname, const char *mountpoint);
  *
  * Initializes a file system on the target.
  *
+ * @note The "volname" parameter of RAM disks should always begin with the string "RAM",
+ * e.g. "RAMDISK" or "RAM0","RAM1", etc if multiple devices are created. The underlying
+ * implementation uses this to select the correct filesystem type/format, and this may
+ * also be used to differentiate between RAM disks and real physical disks.
+ *
  * @param[in] address The address at which to start the new disk. If address == 0,
  * then space will be allocated by the OS
- * @param[in] devname The name of the "generic" drive
- * @param[in] volname The name of the volume (if needed, used on VxWorks)
+ * @param[in] devname The underlying kernel device to use, if applicable.
+ * @param[in] volname The name of the volume (see note)
  * @param[in] blocksize The size of a single block on the drive
  * @param[in] numblocks The number of blocks to allocate for the drive
  *

src/os/posix/src/os-impl-filesys.c

@@ -47,6 +47,7 @@
 /****************************************************************************************
  GLOBAL DATA
  ***************************************************************************************/
+const char OS_POSIX_DEVICEFILE_PREFIX[] = "/dev/";
 
 /****************************************************************************************
  Filesys API
@@ -93,13 +94,26 @@ int32 OS_FileSysStartVolume_Impl (uint32 filesys_id)
  VOLATILE_DISK_LOC_MAX
  };
 
+ /*
+ * Determine basic type of filesystem, if not already known
+ */
+ if (local->fstype == OS_FILESYS_TYPE_UNKNOWN &&
+ strncmp(local->device_name, OS_POSIX_DEVICEFILE_PREFIX, sizeof(OS_POSIX_DEVICEFILE_PREFIX)-1) == 0)
+ {
+ /*
+ * If referring to a real device in the /dev filesystem,
+ * then assume it is a normal disk.
+ */
+ local->fstype = OS_FILESYS_TYPE_NORMAL_DISK;
+ }
 
  /*
- * For RAM_DISK volumes, there are two options:
+ * For VOLATILE volumes, there are two options:
  * - The /dev/shm filesystem, if it exists
  * - The /tmp filesystem
  *
- * The /dev/shm is preferable because it should actually be a ramdisk.
+ * The /dev/shm is preferable because it should actually be a ramdisk, but
+ * it is system-specific - should exist on Linux if it is mounted.
  * The /tmp file system might be a regular persistent disk, but should always exist
  * on any POSIX-compliant OS.
  */
@@ -252,9 +266,10 @@ int32 OS_FileSysMountVolume_Impl (uint32 filesys_id)
  * mount point exists. For any other FS type, trigger an
  * error to indicate that it is not implemented in this OSAL.
  */
- if (local->fstype != OS_FILESYS_TYPE_VOLATILE_DISK)
+ if (local->fstype != OS_FILESYS_TYPE_VOLATILE_DISK &&
+ local->fstype != OS_FILESYS_TYPE_FS_BASED)
  {
- /* the mount command is only allowed on a ram disk */
+ /* the mount command is not implemented for this FS type */
  return OS_ERR_NOT_IMPLEMENTED;
  }
 

src/os/rtems/src/os-impl-filesys.c

@@ -59,6 +59,11 @@ typedef struct
  GLOBAL DATA
  ***************************************************************************************/
 
+/*
+ * The prefix used for "real" device nodes on this platform
+ */
+const char OS_RTEMS_DEVICEFILE_PREFIX[] = "/dev/";
+
 /*
  * The implementation-specific file system state table.
  * This keeps record of the RTEMS driver and mount options for each filesystem
@@ -116,12 +121,25 @@ int32 OS_FileSysStartVolume_Impl (uint32 filesys_id)
  return_code = OS_ERR_NOT_IMPLEMENTED;
  memset(impl,0,sizeof(*impl));
 
+ /*
+ * Determine basic type of filesystem, if not already known
+ */
+ if (local->fstype == OS_FILESYS_TYPE_UNKNOWN &&
+ strncmp(local->device_name, OS_RTEMS_DEVICEFILE_PREFIX, sizeof(OS_RTEMS_DEVICEFILE_PREFIX)-1) == 0)
+ {
+ /*
+ * If referring to a real device in the /dev filesystem,
+ * then assume it is a normal disk.
+ */
+ local->fstype = OS_FILESYS_TYPE_NORMAL_DISK;
+ }
+
  /*
  * Take action based on the type of volume
  */
  switch (local->fstype)
  {
- case OS_FILESYS_TYPE_DEFAULT:
+ case OS_FILESYS_TYPE_FS_BASED:
  {
  /*
  * This "mount" type is basically not a mount at all,
@@ -244,7 +262,7 @@ int32 OS_FileSysFormatVolume_Impl (uint32 filesys_id)
 
  switch(local->fstype)
  {
- case OS_FILESYS_TYPE_DEFAULT:
+ case OS_FILESYS_TYPE_FS_BASED:
  {
  /*
  * In this mode a format is a no-op, as it is simply a directory
@@ -323,14 +341,22 @@ int32 OS_FileSysMountVolume_Impl (uint32 filesys_id)
  }
 
  /*
- ** Mount the Disk
- */
- if ( mount(impl->blockdev_name, local->system_mountpt,
- impl->mount_fstype, impl->mount_options, impl->mount_data) != 0 )
+ * Only do the mount() syscall for real devices.
+ * For other types of filesystem mounts (e.g. FS_BASED), this is a no-op
+ */
+ if (local->fstype == OS_FILESYS_TYPE_VOLATILE_DISK ||
+ local->fstype == OS_FILESYS_TYPE_NORMAL_DISK)
  {
- OS_DEBUG("OSAL: Error: mount of %s to %s failed: %s\n",
- impl->blockdev_name, local->system_mountpt, strerror(errno));
- return OS_ERROR;
+ /*
+ ** Mount the Disk
+ */
+ if ( mount(impl->blockdev_name, local->system_mountpt,
+ impl->mount_fstype, impl->mount_options, impl->mount_data) != 0 )
+ {
+ OS_DEBUG("OSAL: Error: mount of %s to %s failed: %s\n",
+ impl->blockdev_name, local->system_mountpt, strerror(errno));
+ return OS_ERROR;
+ }
  }
 
  return OS_SUCCESS;
@@ -350,13 +376,17 @@ int32 OS_FileSysUnmountVolume_Impl (uint32 filesys_id)
 {
  OS_filesys_internal_record_t *local = &OS_filesys_table[filesys_id];
 
- /*
- ** Try to unmount the disk
- */
- if ( unmount(local->system_mountpt) < 0)
+ if (local->fstype == OS_FILESYS_TYPE_VOLATILE_DISK ||
+ local->fstype == OS_FILESYS_TYPE_NORMAL_DISK)
  {
- OS_DEBUG("OSAL: RTEMS unmount of %s failed :%s\n",local->system_mountpt, strerror(errno));
- return OS_ERROR;
+ /*
+ ** Try to unmount the disk
+ */
+ if ( unmount(local->system_mountpt) < 0)
+ {
+ OS_DEBUG("OSAL: RTEMS unmount of %s failed :%s\n",local->system_mountpt, strerror(errno));
+ return OS_ERROR;
+ }
  }
 
  return OS_SUCCESS;

src/os/shared/inc/os-shared-filesys.h

@@ -69,7 +69,8 @@
  */
 enum
 {
- OS_FILESYS_TYPE_DEFAULT = 0, /**< Unspecified or unknown file system type */
+ OS_FILESYS_TYPE_UNKNOWN = 0, /**< Unspecified or unknown file system type */
+ OS_FILESYS_TYPE_FS_BASED, /**< A emulated virtual file system that maps to another file system location */
  OS_FILESYS_TYPE_NORMAL_DISK, /**< A traditional disk drive or something that emulates one */
  OS_FILESYS_TYPE_VOLATILE_DISK, /**< A temporary/volatile file system or RAM disk */
  OS_FILESYS_TYPE_MTD, /**< A "memory technology device" such as FLASH or EEPROM */

src/os/shared/src/osapi-filesys.c

@@ -62,6 +62,14 @@ extern const OS_VolumeInfo_t OS_VolumeTable[];
 
 #endif
 
+/*
+ * A string that should be the prefix of RAM disk volume names, which
+ * provides a hint that the file system refers to a RAM disk.
+ *
+ * If multiple RAM disks are required then these can be numbered,
+ * e.g. RAM0, RAM1, etc.
+ */
+const char OS_FILESYS_RAMDISK_VOLNAME_PREFIX[] = "RAM";
 
 /*----------------------------------------------------------------
  *
@@ -146,6 +154,7 @@ int32 OS_FileSys_InitLocalFromVolTable(OS_filesys_internal_record_t *local, cons
  */
  if (Vol->VolumeType == FS_BASED)
  {
+ local->fstype = OS_FILESYS_TYPE_FS_BASED;
  local->flags |= OS_FILESYS_FLAG_IS_FIXED;
  }
  else if (Vol->VolumeType == RAM_DISK || Vol->VolatileFlag)
@@ -287,24 +296,7 @@ int32 OS_FileSys_Initialize(char *address, const char *fsdevname, const char * f
 
  /* Get the initial settings from the classic volume table.
  * If this fails, that is OK - because passed-in values get preference anyway */
- if (OS_FileSys_SetupInitialParamsForDevice(fsdevname, local) != OS_SUCCESS)
- {
- /*
- * No known parameters for the device.
- *
- * if address was supplied, assume it is a RAM disk, otherwise
- * assume it is a regular disk.
- */
- if (address == NULL)
- {
- local->fstype = OS_FILESYS_TYPE_NORMAL_DISK;
- }
- else
- {
- local->fstype = OS_FILESYS_TYPE_VOLATILE_DISK;
- }
-
- }
+ OS_FileSys_SetupInitialParamsForDevice(fsdevname, local);
 
  /* populate the VolumeName and BlockSize ahead of the Impl call,
  * so the implementation can reference this info if necessary */
@@ -313,6 +305,21 @@ int32 OS_FileSys_Initialize(char *address, const char *fsdevname, const char * f
  local->address = address;
  strcpy(local->volume_name, fsvolname);
 
+ /*
+ * Determine basic type of filesystem, if not already known
+ *
+ * if either an address was supplied, or if the volume name 
+ * contains the string "RAM" then it is a RAM disk. Otherwise
+ * leave the type as UNKNOWN and let the implementation decide.
+ */
+ if (local->fstype == OS_FILESYS_TYPE_UNKNOWN &&
+ (local->address != NULL || 
+ strncmp(local->volume_name, OS_FILESYS_RAMDISK_VOLNAME_PREFIX, 
+ sizeof(OS_FILESYS_RAMDISK_VOLNAME_PREFIX)-1) == 0))
+ {
+ local->fstype = OS_FILESYS_TYPE_VOLATILE_DISK;
+ }
+
  return_code = OS_FileSysStartVolume_Impl(local_id);
 
  if (return_code == OS_SUCCESS)
@@ -487,11 +494,30 @@ int32 OS_FileSysAddFixedMap(uint32 *filesys_id, const char *phys_path, const cha
  /*
  * mark the entry that it is a fixed disk
  */
- local->flags =
- OS_FILESYS_FLAG_IS_FIXED |
- OS_FILESYS_FLAG_IS_READY |
- OS_FILESYS_FLAG_IS_MOUNTED_SYSTEM |
- OS_FILESYS_FLAG_IS_MOUNTED_VIRTUAL;
+ local->fstype = OS_FILESYS_TYPE_FS_BASED;
+ local->flags = OS_FILESYS_FLAG_IS_FIXED;
+
+ /*
+ * The "mount" implementation is required as it will
+ * create the mountpoint if it does not already exist
+ */
+ return_code = OS_FileSysStartVolume_Impl(local_id);
+
+ if (return_code == OS_SUCCESS)
+ {
+ local->flags |= OS_FILESYS_FLAG_IS_READY;
+ return_code = OS_FileSysMountVolume_Impl(local_id);
+ }
+
+ if (return_code == OS_SUCCESS)
+ {
+ /*
+ * mark the entry that it is a fixed disk
+ */
+ local->flags |=
+ OS_FILESYS_FLAG_IS_MOUNTED_SYSTEM |
+ OS_FILESYS_FLAG_IS_MOUNTED_VIRTUAL;
+ }
 
  /* Check result, finalize record, and unlock global table. */
  return_code = OS_ObjectIdFinalizeNew(return_code, global, filesys_id);
@@ -671,11 +697,12 @@ int32 OS_mount (const char *devname, const char* mountpoint)
  /* mount() cannot be used on this file system at this time */
  return_code = OS_ERR_INCORRECT_OBJ_STATE;
  }
- else if ((local->flags & OS_FILESYS_FLAG_IS_FIXED) != 0)
+ else if (local->system_mountpt[0] == 0)
  {
- /* Won't mount if FIXED, but return SUCCESS for compatibility
- * with existing apps/PSP that attempt this operation. */
- return_code = OS_SUCCESS;
+ /*
+ * The system mount point should be a non-empty string.
+ */
+ return_code = OS_FS_ERR_PATH_INVALID;
  }
  else
  {
@@ -751,12 +778,6 @@ int32 OS_unmount (const char *mountpoint)
  /* unmount() cannot be used on this file system at this time */
  return_code = OS_ERR_INCORRECT_OBJ_STATE;
  }
- else if ((local->flags & OS_FILESYS_FLAG_IS_FIXED) != 0)
- {
- /* Won't unmount if FIXED, but return SUCCESS for compatibility
- * with existing apps/PSP that attempt this operation. */
- return_code = OS_SUCCESS;
- }
  else
  {
  return_code = OS_FileSysUnmountVolume_Impl(local_id);