UTFS TAR-like – A new UTFS format aims to make storage management on resource-constrained embedded devices less painful. Built as a Micro (µ) Tar File System, it compares itself to TAR in spirit while staying small enough to fit in C99 across two source files with zero heap u
For developers building on resource-constrained embedded platforms, storage can turn into a trap. Drag in a filesystem dependency designed for heavier environments and you pay for it twice: the binary grows, and the filesystem overhead adds more weight than the device can spare.
A new UTFS format—short for Micro (µ) Tar File System—tries to cut through that. The premise is straightforward: instead of treating storage as a single blob of raw binary data, UTFS lets sections of the storage behave like files, with updates that can be made in place.
The concept is deliberately familiar but scaled down. UTFS follows the same broad idea as the venerable Tape ARchive (TAR) format. but it’s “very much slimmed down” to suit embedded constraints. The provided UTFS implementation is kept lean: it spans two source files in C99 and uses zero heap memory. That detail matters in the embedded world, where heap availability can be a luxury rather than a guarantee.
UTFS also doesn’t try to assume the hardware. To target a custom storage medium, the implementation asks for only two functions—one for reads and one for writes—so the rest of the format can plug into whatever lives under the platform.
The project includes concrete examples showing how UTFS behaves on real hardware-style storage. One example targets the built-in Flash of a SAMD20 MCU. Another works with the EEPROM of an ATmega328. In both cases, UTFS is positioned as an alternative to rewriting everything whenever a small change is needed. With raw binary data, updating typically means starting over and rewriting the full contents. UTFS, by contrast, is meant to make storage sections accessible “as files,” so they can be updated in place.
What makes the approach compelling isn’t just its familiarity to anyone who’s seen TAR—it’s the discipline around cost. With the implementation kept to two C99 source files. zero heap usage. and only a pair of platform hooks for I/O. UTFS is built around the reality that embedded developers often can’t afford general-purpose filesystem bloat.
It’s a small change in how you think about storage, but in environments with tight budgets, that can be the difference between shipping and waiting.
UTFS Micro Tar File System embedded storage filesystem for embedded C99 zero heap usage SAMD20 Flash ATmega328 EEPROM in-place updates