reword misleading comment in struct got_repository WRT struct got_pack

gotd no longer uses chroot; remove comments suggesting otherwise

add got_repo_get_object_format() and use it to avoid hardcoding the digest type in a few places. ok stsp@

got-read-gitconfig: send key-value pairs for extensions Most extension allow only for a boolean value so the current behaviour of just sending the extension with a trueish value is fine. However, some extensions that we could eventually support (like "objectformat") have a string value. This is a preparatory step towards that. ok stsp@

use sub-second precision when checking for objects/pack/ modification Convert from st.m_time (second-precision time_t) to st.m_tim (struct timespec). To compensate for the potential case where a filesystem provides resolution in seconds only, always read the directory if no pack files are known to exist. Otherwise, there is a race condition when gotd repo_write creates a new pack and a request arrives for repo_read shortly after. Caught by a regression test for gotd on empty repositories. Test failure pointed out by Mikhail. ok op@

introduce gotd(8), a Git repository server reachable via ssh(1) This is an initial barebones implementation which provides the absolute minimum of functionality required to serve got(1) and git(1) clients. Basic fetch/send functionality has been tested and seems to work here, but this server is not yet expected to be stable. More testing is welcome. See the man pages for setup instructions. The current design uses one reader and one writer process per repository, which will have to be extended to N readers and N writers in the future. At startup, each process will chroot(2) into its assigned repository. This works because gotd(8) can only be started as root, and will then fork+exec, chroot, and privdrop. At present the parent process runs with the following pledge(2) promises: "stdio rpath wpath cpath proc getpw sendfd recvfd fattr flock unix unveil" The parent is the only process able to modify the repository in a way that becomes visible to Git clients. The parent uses unveil(2) to restrict its view of the filesystem to /tmp and the repositories listed in the configuration file gotd.conf(5). Per-repository chroot(2) processes use "stdio rpath sendfd recvfd". The writer defers to the parent for modifying references in the repository to point at newly uploaded commits. The reader is fine without such help, because Git repositories can be read without having to create any lock-files. gotd(8) requires a dedicated user ID, which should own repositories on the filesystem, and a separate secondary group, which should not have filesystem-level repository access, and must be allowed access to the gotd(8) socket. To obtain Git repository access, users must be members of this secondary group, and must have their login shell set to gotsh(1). gotsh(1) connects to the gotd(8) socket and speaks Git-protocol towards the client on the other end of the SSH connection. gotsh(1) is not an interactive command shell. At present, authenticated clients are granted read/write access to all repositories and all references (except for the "refs/got/" and the "refs/remotes/" namespaces, which are already being protected from modification). While complicated access control mechanism are not a design goal, making it possible to safely offer anonymous Git repository access over ssh(1) is on the road map.

move declaration of got_privsep_child out of got_lib_privsep.h This declaration is the only reason why got_lib_privsep.h must be included in order to use got_lib_repository.h. Moving this declaration will allow for cleaning up unnecessary includes of got_lib_privsep.h.

move code for reading Git's config file into new file read_gitconfig_privsep.c The end goal here is to remove the dependency of repository.c on privsep.c during compilation.

refresh our pack-index path list if the mtime of objects/pack has changed ok op@

implement support for commit coloring in got-read-pack for speed ok op, tracey

reduce GOT_PACK_CACHE_SIZE to 32, otherwise it uses too many open files found by tracey

cache a list of known pack index files when the repository is opened Avoids overhead due to readdir calls while searching a pack index. ok op@

reuse existing deltas when creating pack files tested by thomas, naddy, and myself

cache raw objects in order to speed up gotadmin pack

use RB_TREE instead of STAILQ to manage packindex bloom filters; much faster