Module `Tjr_path_resolution.Path_resolution`

Path resolution algorithm

The SibylFS spec contains a description of path resolution, parameterized for all the crazy behavioural differences (especially on Mac).

The following is an attempt to impose a comprehensible structure on the real-world messiness. The algorithm below executes a version of path resolution which takes account of the weirdnesses in real-world behaviour. It is structured so that

it "naturally" follows some notion of path resolution which is general enough to account for real-world behaviour
it makes minimal commitments at each stage
it tries to preserve complete information (of course, it drops bits of the path that have resolved uncontroversially)
path resolution is broken down into stages
getting the "next" path component
updating the state and returning a result
finally, implementing path resolution recursively
small steps are taken!
what is happening is clear at each step
the code is parameterized over the filesystem implementation (fs_ops)

At the moment, we do not take account of MAX_SYMLINK, MAX_PATH etc. But these are easy to add.

NOTE one of the problems is the overloading of '/' as a component separator, the root (not so bad) and an indicator that a symlink should be resolved

TODO:

add MAX_SYMLINK and MAX_PATH

construct a unix/windows path compatibility library based on this code

add testing and code coverage

test this code against SibylFS model and real-world traces; replace SibylFS model with this one

val is_finished : 'a Intf.state -> bool
val state_from_symlink : cwd:'a -> symlink_contents:string -> path:string -> 'a Intf.state
val get_next_comp : 'a Intf.state -> [> `Comp_with_slash of string | `Finished_no_slash of string | `Finished_slash of string | `Root_finished | `Root_unfinished ] * 'a Intf.state
val step : monad_ops:'a Tjr_monad.monad_ops -> fs_ops:('b, 'c, 'd, 'a) Intf.fs_ops -> 'c Intf.state -> ([> `Error of [> `File_followed_by_slash_etc of 'c Intf.state * Intf.comp_ * 'b ] | `Finished_no_slash of Intf.comp_ * 'c | `Finished_root | `Finished_slash of Intf.comp_ * 'c | `Missing_slash of Intf.comp_ * 'c Intf.state | `Ok of 'c Intf.state ], 'a) Tjr_monad.m
val resolve_butlast : monad_ops:'a Tjr_monad.monad_ops -> fs_ops:('b, 'c, 'd, 'a) Intf.fs_ops -> cwd:'c -> string -> ([> `Error of [> `File_followed_by_slash_etc of 'c Intf.state * Intf.comp_ * 'b ] | `Finished_no_slash of Intf.comp_ * 'c | `Finished_root | `Finished_slash of Intf.comp_ * 'c | `Missing_slash of Intf.comp_ * 'c Intf.state ], 'a) Tjr_monad.m: Resolve all but the last component; not used by the main `resolve` function

val resolve' : monad_ops:'a Tjr_monad.monad_ops -> fs_ops:('b, 'c, 'd, 'a) Intf.fs_ops -> follow_last_symlink:Intf.follow_last_symlink -> cwd:'c -> string -> ([> `Error of [> `File_followed_by_slash_etc of 'c Intf.state * Intf.comp_ * 'b ] | `Finished_no_slash_dir of 'c * Intf.comp_ * 'c | `Finished_no_slash_file of 'c * Intf.comp_ * 'b | `Finished_no_slash_symlink of 'c * Intf.comp_ * 'd * string | `Finished_root | `Finished_slash_dir of 'c * Intf.comp_ * 'c | `Finished_slash_file of 'c * Intf.comp_ * 'b | `Missing_finished_no_slash of 'c * Intf.comp_ | `Missing_finished_slash of 'c * Intf.comp_ | `Missing_slash of Intf.comp_ * 'c Intf.state ], 'a) Tjr_monad.m
val simplified_result_root : fs_ops:('a, 'b, 'c, 'd) Intf.fs_ops -> ('e, 'b, 'f) Intf.simplified_result: a "special" result for root

val resolve_simplified : monad_ops:'a Tjr_monad.monad_ops -> fs_ops:('b, 'c, 'd, 'a) Intf.fs_ops -> follow_last_symlink:Intf.follow_last_symlink -> cwd:'c -> string -> ((('b, 'c, 'd) Intf.simplified_result, [> `File_followed_by_slash_etc of 'c Intf.state * Intf.comp_ * 'b | `Missing_slash_etc of Intf.comp_ * 'c * string ]) Stdlib.result, 'a) Tjr_monad.m
val resolve : monad_ops:'t Tjr_monad.monad_ops -> fs_ops:('fid, 'did, 'sid, 't) Intf.fs_ops -> follow_last_symlink:Intf.follow_last_symlink -> cwd:'did -> string -> ((('fid, 'did, 'sid) Intf.simplified_result, [> `File_followed_by_slash_etc of 'did Intf.state * Intf.comp_ * 'fid | `Missing_slash_etc of Intf.comp_ * 'did * string ]) Stdlib.result, 't) Tjr_monad.m