roobie / fspec-tools

Tools to create filesystem images from an fspec filesystem specification.

fspec-tools

Tools to create filesystem images from an fspec filesystem specification.

Examples

Generate an fspec from the current directory:

$ fspec-fromdir

/README.md
type=reg
mode=0644
uid=1000
gid=100

...

Generate an fspec from another directory:

$ fspec-fromdir -C / dev

/dev/null
type=chardev
devnum=259
mode=0666
uid=0
gid=0

...

Create a tarball:

$ fspec-tar < fs.fspec | gzip > out.tar.gz

Create an initramfs:

$ fspec-cpio < fs.fspec | gzip > out.cpio.gz

Extract a tarball:

# no root needed for special devices
$ gzip -d < fs.tar.gz | fspec-fromarchive -d ./data > fs.fspec

Format

fspec     ::= record ("\n" record)* "\n"?
record    ::= name attribute+
name      ::= "/" [^\n]* "\n"
attribute ::= [a-zA-Z0-9_]+ "=" [^\n]+ "\n"

An fspec file consists of a sequence of records separated by blank lines. Each record describes a node in the filesystem. The first line in a record is the file path, and it is followed by one or more attribute lines. Since newline characters are used to separate the parts of a record, they are banned from file names and attribute values.

The following attributes are available:

• type (required): Type of filesystem node.
  • reg: Regular file
  • sym: Symbolic link
  • dir: Directory
  • fifo: FIFO special file.
  • chardev: Character device node
  • blockdev: Block device node
• mode: File permission bits, represented as exactly four octal digits. If not present, the default depends on type:
  • reg: 0644
  • sym: 0777
  • dir: 0755
  • fifo: 0644
  • chardev: 0600
  • blockdev: 0600
• uid: File owner's ID. If not present, 0 is used.
• gid: File group's ID. If not present, 0 is used.
• source: Local path to file containing the contents to be added to the filesystem image. Only valid for type=reg. If not present, the entry name is used, relative to the directory containing the manifest.
• target: Symlink target. Only valid and required for type=sym.
• devnum: Device number. Only valid and required for type=chardev or type=blockdev.