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libfossil: Fossil SCM Library API

See also: download, building, f-tools, DbFunctions, SQLSnippets, HackersGuide, doxygen docs (refreshed from current sources relatively frequently), "s2" script bindings

This source code repository houses an in-development library API for the Fossil SCM. The primary goal is to port existing behaviour into a library form (the v1 app is extremely monolithic in nature). This effort, officially called "libfossil", intends to introduce no breaking changes, and the intention is to provide an alternative interface into fossil repositories, as opposed to a replacement for the core fossil application.

This code currently doesn't do much which would interest non-Fossil hackers. It might be of interest to those wanting to follow or participate in the design of libfossil.

License: same as Fossil: the "2-Clause BSD" a.k.a. "FreeBSD License" with the same license holder (D. Richard Hipp, the primary author and architect of sqlite and Fossil). To keep this code as "license clean" as possible vis-a-vis Fossil, code contributions require having a Fossil copyright waiver on file. All Fossil committers (those who have a signed a license waiver on file with DRH, whether or not they actually commit code to Fossil) are unreservedly welcomed as libfossil contributors - email your preferred user name to get an account: Getting a waiver is a simple matter of filling it out and sending it off to DRH at the address shown on the form (please attach a note indicating that the waiver is for libfossil (as opposed to fossil), so that he knows no additional effort is necessary on his part!). Those without a waiver may of course contribute in other ways (ideas, discussions, docs, ...).

Online Demo

We have an online demonstration of CGI applications implemented using the th1ish bindings to libfossil here:

Those particular script bindings have been obsoleted by newer ones (based on a different language), but the newer ones don't yet have CGI-level demos.

Status, TODOs, and Whatnot

All of this code is an experiment, and it does not represent a commitment by anyone that any of this code will some day end up living under the umbrella of the larger Fossil SCM project. If all goes well, that's the eventual goal, though. It is alpha quality. What's there works but is subject to change and there is still a great deal of the higher-level SCM bits left to port in and refactor to make them usable via library-style interfaces. Anyone looking for a project roadmap/timeline is asked respectfully to look elsewhere - there is no timebox on nor schedule for this project/experiment. That said: the f-tools demonstrate what functionality is working.

The code changes can be followed via the timeline.

The current public (and documented) API can be found in the header files, and occasionally that gets exported to doxygen.

TODOs, design discussions, etc... you might want to get a coffee/tee/beer before starting through the list.

"Rules" for Code Contributors

  • All code contributors must have a license waiver on file with DRH, as the hope is to eventually release this code as the next generation of Fossil. Non-code contributions are happily accepted from anyone.
  • When working on bits which themselves write to the repository, e.g. creating checkins, please be exceedingly careful not to corrupt the db :-D.
  • Please try to conform to the overall coding style (as laid out by Fossil v1). We're not picky about whether or not spaces belong before/after an if, but the general overall style should be uniform.
  • Please build with the highest possible warning level and enable fatal warnings (in GCC and similar compilers: -Wall -Werror).
  • Don't bother using branches unless you really want to - the trunk has no stability guarantees and is very much in flux, so feel free to work there instead of a branch if you like.

There is nothing holy or sacred about this repo, so feel free to hack at will. Most of the library's sanity tests are packaged in f-sanity.c. See fossil-cli.h for a mini-framework to bootstrap new apps and f-tools.


Notable changes (newest at the top)...

  • 20130919: Realized i hadn't updated the news in a while. Future news will be posted as Events in the /timeline.
  • 20130901: Milestone: side-by-side (SBS) diff generation was ported in.
  • 20130831: Milestone: the basic diff-generation code has been ported in (context diffs only, not yet SBS).
  • 20130828: Milestone: we can now create new repos.
  • 20130825: Minor milestone: clients can now hook in to the crosslinking phase. This is the first step needed for generating native-language timeline views.
  • 20130824: Minor milestone: saved the first wiki changes today.
  • 20130822: Milestone: the "verify at commit" operation, which ensures that fossil can actually read back what the user would like to save before the transaction is committed, is in place and working (or not failing ;). This was the last missing piece of the lower-level SCM bits (or the last piece which was holding anything up - there might be more pieces to port once i get around to the 'rebuild' functionality).
  • 20130819: Minor milestone: we can now losslessly round-trip Event Artifacts to/from fossil. Event crosslinking was implemented.
  • 20130816: Milestone: manifest parsing is more or less complete, covering the whole range of control artifact types. Strict validation is done (including the Z-card hash) to ensure that bogus manifests cannot be read (and the generator does the same at several different levels). "Parsing," in this context means converting a raw Fossil manifest to a higher-level (OO) construct. That construct can then be output to a new manifest which is identical to the old one, providing a 100% loss-less round-trip conversion. (Such round-trips are useful only for testing/proof-of-concept, and are not needed in practice.)
  • 20130815: the past couple days have seen many incremental additions to the manifest machinery. We can now "round-trip" some artifact types, parsing them into a high-level form and re-generating them from that high-level form.
  • 20130812: Started the f-tools.
  • 20130811: Got "manifest crosslinking" of control artifact (tag changes) ported in.
  • 20130810: Milestone: the library saved its first tag today! (The timestamp of the tag was intentionally falsified for testing purposes.)
  • 20130808: Restructured source tree and ported build configuration process to autosetup (because that's what Fossil uses). Existing build files (not the sources) still require GNU Make on a Unix platform, though. Many thanks to Steve Bennett (autosetup's author) for his assistance.
  • 20130804: ported in the symbol-to-uuid resolution bits from the main repo. These are what allow apps to use short-form UUIDs and symbolic names like "trunk," instead of having to use 40-byte UUIDs everywhere.
  • 20130803: most of the infrastructure for creating manifests and control artifacts is in place, but we don't yet write them to the db.
  • 20130801: ported in the delta generation/apply code and added script bindings for them.
  • 20130730: changed internal handling of DBs from 1 connection per db to a single main connection to an in-memory db and attaching the repo/config/checkout to that. Not yet sure if this is a feature or a bug, but it simplifies the internal tracking of db handles notably.
  • 20130728: it can now search for and open a checkout based on a directory name, analog to how v1 finds an open checkout.
  • 20130727: started work on a th1ish script engine binding for v2. It is of course a work-in-progress but it is extended in parallel to the core lib because that simplifies testing and helps work the kinks out of the core API.
  • 20130726: when opening a repo db, the library now validates that it is a repo db, and can distinguish between/report various types of errors, e.g. repo schema is out of data or the db is not a fossil repo.
  • 20130725: removed the per-instance allocator configuration - it is now library-wide. This simplifies buffer usage and makes it legal to use them before instantiating a fossil context.