populatefs 1.2

A nearly drop-in replacement for genext2fs from tytso/e2fsprogs that is compatible with ext4.

version 1.1+ has added support for offset images

version 1.2 adds the -d @/top-dir syntax to allow composing multiple root-level-dirs into an image.

Image generation

To produce a 42MiB filesytem image:

label=OpenWrt
inodes=8096
fsopts=has_journal,ext_attr,resize_inode,dir_index,filetype,extent,flex_bg,sparse_super,large_file,uninit_bg,dir_nlink,extra_isize

dd if=/dev/zero of=root.ext4 seek=42720 count=0 bs=1k
mkfs.ext4 -F -E root_owner=0:0 -L $label] -N $inodes -O $fsopts -m 0 root.ext4

then use populatefs to populate the empty filesystem: populatefs -U -d [directory containing files to go into root] -D devtable.txt root.ext4

Usage

Usage:./populatefs [options] (image | diskimage?offset=<starting-byte-of-ext4-partition>)"
Manipulate ext4 images from directories/files

 -d @/directory   Add the given directory to the image's root as-a-dir
 -d <directory>   Add the given directory's contents into the image's root
 -D <file>        Add device nodes and directories from filespec
 -U               Squash owners making all files be owner by root:root
 -P               Squash permissions on all files
 -q               Same as "-U -P"
 -S <number>      Shift UIDs & GIDs by decrementing S-many from source value
 -h               Display this usage guide
 -V               Show version
 -v               Be verbose
 -w               Be even more verbose

Advanced use

You can add multiple directories of filespecs with multiple -d or -D options.
These are processed in the order you give 'em to command-line.

If these sources contain pathnames that will overlap:

previously added files will be overwritten by new files.
previously added directories will include new source's files.
error will be printed out if adding a directory and that pathname is already a file.

Rules are simple: do not overwrite directory with file, or file with directory.

Offset-images ("disk images") can be handled using some under-documented syntax to provide the starting byte of the EXT superblock.

The same offset can be used to perform a loop-mount to verify the image contents.

Compilation

No autohell, just a Makefile with overridable variables.

CC=gcc make or CC=gcc DESTDIR=/tmp make install

Study the values from Makefile. If your system did not ship or does not have getopt.. Try: EXTRA_CFLAGS="" make

Requirements

libext2fs and libmath must be available for compilation.

Debian: sudo apt-get install libext2fs-dev libc6-dev

For runtime, kernel must have support for debugfs.

Credits

This is a fork from oskarirauta/populatefs 0.9 & lipnitsk/populatefs 1.0

kfix / populatefs