File System

Principle

The FS module defines a low-level File System framework for embedded devices. It allows you to manage abstract files and directories without worrying about the native underlying File System kind.

Functional Description

The MicroEJ Application manages File System elements using File/Directory abstraction. The FS implementation made for each MicroEJ Platform is responsible for surfacing the native File System specific behavior.

Dependencies

Installation

FS is an additional module. In the platform configuration file, check FS to install it. When checked, the properties file fs/fs.properties is required during platform creation in order to configure the module. This properties file specifies the characteristics of the File System used in the C project (case sensitivity, root directory, file separator, etc.).

The FS module defines two pre-configured File System types: Unix and FatFS. Some characteristics don’t need to be specified for these File System types, but they can be overridden if needed. For example, specifying a Unix File System type will automatically set the file separator to /.

If none of the pre-configured File System types correspond to the File System used in the C project, the Custom type can be used. When this type is selected, all the File System characteristics must be specified in the properties file.

The list below describes the properties that can be defined in the file fs/fs.properties:

  • fs: Defines the type of File System used in the C project (optional, the default value is Unix). This property can have one of the following values:
    • Unix: select this configuration when using a Unix-like File System (case-sensitive, file separator is /).
    • FatFS: select this configuration when using FatFS File System (case-insensitive, file separator is /).
    • Custom: select this configuration when using another type of File System.
  • root.dir: Defines the File System root volume. This property is optional for Unix and FatFS (/ by default for both).
  • user.dir: Defines the File System user directory. This property is optional for FatFS (/usr/ by default).
  • java.io.tmpdir: Defines the File System temporary directory. This property is optional for Unix and FatFS (/tmp/ by default for both).
  • file.separator: Defines the File System file separator. This property is optional for Unix and FatFS (/ by default for both).
  • path.separator: Defines the File System path separator. This property is optional for Unix and FatFS (: by default for both).
  • case.sensitivity: Defines the case sensitivity of the File System. This property is optional for Unix (caseSensitive by default) and FatFS (caseInsensitive by default). This property can have one of the following values:
    • caseSensitive: the File System is case-sensitive.
    • caseInsensitive: the File System is case-insensitive.

Properties File Template

The following snippet can be used as a template for fs.properties file:

# Defines the type of File System used in the C project.
# Possible values are:
#   - FatFs
#   - Unix
#   - Custom
# @optional, default value is "Unix"
#fs=

# Defines the File System root volume.
# @optional for the following File System types:
#   - FatFs (default value is "/")
#   - Unix (default value is "/")
# @mandatory for the following File System type:
#   - Custom
#root.dir=

# Defines the File System user directory.
# @optional for the following File System type:
#   - FatFs (default value is "/usr")
# @mandatory for the following File System types:
#   - Unix
#   - Custom
#user.dir=

# Defines the File System temporary directory.
# @optional for the following File System types:
#   - FatFs (default value is "/tmp")
#   - Unix (default value is "/tmp")
# @mandatory for the following File System type:
#   - Custom
#java.io.tmpdir=

# Defines the File System file separator.
# @optional for the following File System types:
#   - FatFs (default value is "/")
#   - Unix (default value is "/")
# @mandatory for the following File System type:
#   - Custom
#file.separator=

# Defines the File System path separator.
# @optional for the following File System types:
#   - FatFs (default value is ":")
#   - Unix (default value is ":")
# @mandatory for the following File System type:
#   - Custom
#path.separator=

# Defines the case sensitivity of the File System.
# Valid values are "caseInsensitive" and "caseSensitive".
# @optional for the following File System types:
#   - FatFs (default value is "caseInsensitive")
#   - Unix (default value is "caseSensitive")
# @mandatory for the following File System type:
#   - Custom
#case.sensitivity=

Use

The FS API Module must be added to the module.ivy of the MicroEJ Application project to use the FS library.

<dependency org="ej.api" name="fs" rev="2.0.6"/>