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Extract EDSL to fsedsl/ library 

- Create fsedsl/ as embedded library with generic types:
  - FsNodeDecl[Ctx], Binding[Ctx], NodeOption[Ctx]
  - BuildTree[Ctx], GenerateHelp[Ctx]
  - Tree, File, FileConfig, SyntheticFileInfo

- Update ollie/fs to use fsedsl via type aliases:
  - type FsNodeDecl = fsedsl.FsNodeDecl[HandlerCtx]
  - Wrapper functions for constructors and options

- Migrate binding functions to Applier pattern:
  - Binding.Applier replaces direct field assignment
  - Cleanly separates EDSL mechanics from domain types

- Add replace directive in go.mod for local module

The library can be extracted to a separate repo later by
changing the module path and removing the replace directive.
This commit is contained in:
Levi Neely 2026-08-04 12:02:32 +02:00
parent 2ae89134d4
commit 882fc598d4
12 changed files with 1592 additions and 302 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

253
fs/edsl.go
View File

@ -1,11 +1,16 @@
package fs package fs
// This file provides type aliases and wrappers that instantiate the generic
// fsedsl types with ollie's HandlerCtx. This allows the fs package to use
// the generic EDSL library while maintaining backward compatibility.
import ( import (
"context" "context"
"os" "os"
"ollie/agent" "ollie/agent"
"ollie/elevate" "ollie/elevate"
"ollie/fsedsl"
olog "ollie/log" olog "ollie/log"
"ollie/skills" "ollie/skills"
"ollie/toolsrv" "ollie/toolsrv"
@ -42,188 +47,180 @@ type HandlerCtx struct {
// BlockFn is the signature for blocking/streaming reads. // BlockFn is the signature for blocking/streaming reads.
type BlockFn func(ctx context.Context, base string) ([]byte, string, error) type BlockFn func(ctx context.Context, base string) ([]byte, string, error)
// Structural permissions — used by Tree for mounted children and synthetic files. // ── Type aliases from fsedsl ─────────────────────────────────────
const (
PermChildDir os.FileMode = 0555
PermIdx os.FileMode = 0444
PermMkdir os.FileMode = 0755
PermMkdirPrivate os.FileMode = 0700
)
// BindingFn returns the bindings for Each to iterate over.
type BindingFn func(ctx HandlerCtx) ([]Binding, error)
// Binding provides identity and data for one iteration of Each.
// The structure is cloned for each binding, and handlers receive
// the bound data via ctx.Session, ctx.Agent, or ctx.AgentLog.
type Binding struct {
Name string // directory name (e.g. session name, agent name)
Aliases []string // alternate lookup names (e.g. immutable ID)
UID string // owner (empty = inherit)
GID string // group (empty = inherit)
// Bound data — handlers access via ctx.Session/Agent/AgentLog/Data.
Session *Session
Agent *agent.Agent
AgentLog *AgentLog
Data any // generic binding for domain-specific data
// Lifecycle callbacks.
Remove func()
Rename func(string) error
}
// BindTarget declares what data an Each block binds to handlers.
type BindTarget int
const (
BindSession BindTarget = iota
BindAgent
BindAgentLog
BindData
BindRemove
BindRename
)
// FsNodeDecl describes one node in the 9P namespace. // FsNodeDecl describes one node in the 9P namespace.
// The entire filesystem is a single recursive tree of these. type FsNodeDecl = fsedsl.FsNodeDecl[HandlerCtx]
type FsNodeDecl struct {
// Identity.
Name string
Aliases []string // alternate names that resolve to this node (e.g. immutable ID)
UID string // "" = inherit from parent
GID string // "" = inherit from parent
Mode os.FileMode // 0 = inherit parent default
Desc string // human-readable description
// Tstat — metadata override (non-nil bypasses Name/UID/GID/Mode/size defaulting).
Stat func() os.FileInfo
// Twalk — children (implies directory; at most one set).
Children []FsNodeDecl // static, known at compile time
Bindings func(HandlerCtx) ([]Binding, error) // Each bindings
BindTargets []BindTarget // declares what Bindings provides
// Tread (non-blocking) + Twrite.
Read func(ctx HandlerCtx) ([]byte, error)
Write func(ctx HandlerCtx, data []byte) error
// Tread — blocking variants (at most one set).
BlockOnce func(ctx HandlerCtx, cctx context.Context, base string) ([]byte, string, error)
Stream func(ctx HandlerCtx, cctx context.Context, base string) ([]byte, string, error)
// Request — rdwr: write triggers result, read returns it once.
Request func(ctx HandlerCtx, data []byte) ([]byte, error)
// Tcreate + Tremove + Trename (directory ops).
Create func(ctx HandlerCtx, name string) error
Remove func(ctx HandlerCtx) error
Rename func(newName string) error
}
// NodeOption configures a FsNodeDecl at construction time. // NodeOption configures a FsNodeDecl at construction time.
type NodeOption func(*FsNodeDecl) type NodeOption = fsedsl.NodeOption[HandlerCtx]
// ── EDSL constructors ──────────────────────────────────────────── // Binding provides identity and data for one iteration of Each.
type Binding = fsedsl.Binding[HandlerCtx]
// DirNode declares a static directory node, optionally with NodeOptions (GID, UID). // Tree is the filesystem tree implementation.
type Tree = fsedsl.Tree
// File is an open handle to a single named blob.
type File = fsedsl.File
// FileTree is a named collection of entries.
type FileTree = fsedsl.FileTree
// FileConfig implements File via function pointers.
type FileConfig = fsedsl.FileConfig
// SyntheticFileInfo implements os.FileInfo for entries with no backing file.
type SyntheticFileInfo = fsedsl.SyntheticFileInfo
// SyntheticEntry implements os.DirEntry for entries with no backing file.
type SyntheticEntry = fsedsl.SyntheticEntry
// TreeOption configures a Tree.
type TreeOption = fsedsl.TreeOption
// ── Re-exported constants ────────────────────────────────────────
// Structural permissions — used by Tree for mounted children and synthetic files.
const (
PermChildDir = fsedsl.PermChildDir
PermIdx = fsedsl.PermIdx
PermMkdir = fsedsl.PermMkdir
PermMkdirPrivate = fsedsl.PermMkdirPrivate
)
// BindTarget declares what data an Each block binds to handlers.
// These are advisory — the actual binding is done by Binding.Applier.
type BindTarget = fsedsl.BindTarget
const (
BindData = fsedsl.BindData
)
// Legacy bind targets for backward compatibility.
// These are no longer meaningful since we use Applier, but keep them
// to avoid breaking existing code that references them.
const (
BindSession BindTarget = 100 + iota // deprecated: use Applier
BindAgent // deprecated: use Applier
BindAgentLog // deprecated: use Applier
BindRemove // deprecated: use Applier
BindRename // deprecated: use Applier
)
// ── EDSL constructors (wrappers) ─────────────────────────────────
// DirNode declares a static directory node.
func DirNode(name string, args ...any) FsNodeDecl { func DirNode(name string, args ...any) FsNodeDecl {
d := FsNodeDecl{Name: name} return fsedsl.DirNode[HandlerCtx](name, args...)
for _, a := range args {
switch v := a.(type) {
case FsNodeDecl:
d.Children = append(d.Children, v)
case NodeOption:
v(&d)
}
}
return d
} }
// Each declares a directory that is instantiated for each binding in a collection. // Each declares a directory that is instantiated for each binding in a collection.
// Use Bind() to declare what data handlers receive; the bindings function provides it. func Each(name string, bindings func(HandlerCtx) ([]Binding, error), args ...any) FsNodeDecl {
// return fsedsl.Each(name, bindings, args...)
// Example:
//
// Each("{sname}", sessionBindings,
// Bind(BindSession),
// FileNode("name", 0666, Read(readSessionName)),
// )
func Each(name string, bindings BindingFn, args ...any) FsNodeDecl {
d := FsNodeDecl{Name: name, Bindings: bindings}
for _, a := range args {
switch v := a.(type) {
case FsNodeDecl:
d.Children = append(d.Children, v)
case NodeOption:
v(&d)
}
}
return d
} }
// FileNode declares a file node (non-directory). // FileNode declares a file node (non-directory).
func FileNode(name string, mode os.FileMode, opts ...NodeOption) FsNodeDecl { func FileNode(name string, mode os.FileMode, opts ...NodeOption) FsNodeDecl {
d := FsNodeDecl{Name: name, Mode: mode} return fsedsl.FileNode[HandlerCtx](name, mode, opts...)
for _, o := range opts {
o(&d)
}
return d
} }
// ── Options ────────────────────────────────────────────────────── // ── Options (wrappers) ───────────────────────────────────────────
func Read(fn func(HandlerCtx) ([]byte, error)) NodeOption { func Read(fn func(HandlerCtx) ([]byte, error)) NodeOption {
return func(d *FsNodeDecl) { d.Read = fn } return fsedsl.Read(fn)
} }
func Write(fn func(HandlerCtx, []byte) error) NodeOption { func Write(fn func(HandlerCtx, []byte) error) NodeOption {
return func(d *FsNodeDecl) { d.Write = fn } return fsedsl.Write(fn)
} }
func Stream(fn func(HandlerCtx, context.Context, string) ([]byte, string, error)) NodeOption { func Stream(fn func(HandlerCtx, context.Context, string) ([]byte, string, error)) NodeOption {
return func(d *FsNodeDecl) { d.Stream = fn } return fsedsl.Stream(fn)
} }
func BlockOnce(fn func(HandlerCtx, context.Context, string) ([]byte, string, error)) NodeOption { func BlockOnce(fn func(HandlerCtx, context.Context, string) ([]byte, string, error)) NodeOption {
return func(d *FsNodeDecl) { d.BlockOnce = fn } return fsedsl.BlockOnce(fn)
} }
func Request(fn func(HandlerCtx, []byte) ([]byte, error)) NodeOption { func Request(fn func(HandlerCtx, []byte) ([]byte, error)) NodeOption {
return func(d *FsNodeDecl) { d.Request = fn } return fsedsl.Request(fn)
} }
func CreateFile(fn func(HandlerCtx, string) error) NodeOption { func CreateFile(fn func(HandlerCtx, string) error) NodeOption {
return func(d *FsNodeDecl) { d.Create = fn } return fsedsl.CreateFile(fn)
} }
func Remove(fn func(HandlerCtx) error) NodeOption { func Remove(fn func(HandlerCtx) error) NodeOption {
return func(d *FsNodeDecl) { d.Remove = fn } return fsedsl.RemoveNode(fn)
} }
func Stat(fn func() os.FileInfo) NodeOption { func Stat(fn func() os.FileInfo) NodeOption {
return func(d *FsNodeDecl) { d.Stat = fn } return fsedsl.StatOverride[HandlerCtx](fn)
} }
func UID(uid string) NodeOption { func UID(uid string) NodeOption {
return func(d *FsNodeDecl) { d.UID = uid } return fsedsl.UID[HandlerCtx](uid)
} }
func GID(gid string) NodeOption { func GID(gid string) NodeOption {
return func(d *FsNodeDecl) { d.GID = gid } return fsedsl.GID[HandlerCtx](gid)
} }
func Alias(names ...string) NodeOption { func Alias(names ...string) NodeOption {
return func(d *FsNodeDecl) { d.Aliases = append(d.Aliases, names...) } return fsedsl.Alias[HandlerCtx](names...)
} }
// Bind declares how Each bindings populate HandlerCtx. // Bind declares how Each bindings populate HandlerCtx.
// The BindTarget specifies which field(s) the binding provides. // This is advisory metadata — the actual binding is done by Binding.Applier.
func Bind(targets ...BindTarget) NodeOption { func Bind(targets ...BindTarget) NodeOption {
return func(d *FsNodeDecl) { d.BindTargets = append(d.BindTargets, targets...) } return fsedsl.Bind[HandlerCtx](targets...)
} }
// Doc sets a human-readable description for the node. // Doc sets a human-readable description for the node.
func Doc(desc string) NodeOption { func Doc(desc string) NodeOption {
return func(d *FsNodeDecl) { d.Desc = desc } return fsedsl.Doc[HandlerCtx](desc)
}
// ── Tree construction (wrappers) ─────────────────────────────────
// BuildTree walks an FsNodeDecl spec and produces a *Tree.
func BuildTree(spec FsNodeDecl, rootCtx HandlerCtx) *Tree {
return fsedsl.BuildTree(spec, rootCtx)
}
// NewTree creates a Tree backed by one or more directories.
func NewTree(dirs []string, perm os.FileMode, opts ...TreeOption) *Tree {
return fsedsl.NewTree(dirs, perm, opts...)
}
// Tree options
var (
WithReadOnly = fsedsl.WithReadOnly
WithIndex = fsedsl.WithIndex
WithResolver = fsedsl.WithResolver
WithLister = fsedsl.WithLister
WithCreator = fsedsl.WithCreator
WithDeleter = fsedsl.WithDeleter
WithRenamer = fsedsl.WithRenamer
WithOpener = fsedsl.WithOpener
WithStat = fsedsl.WithStat
WithReaddir = fsedsl.WithReaddir
)
// ── Helpers (wrappers) ───────────────────────────────────────────
// FileEntry returns a synthetic file DirEntry.
func FileEntry(name string, mode os.FileMode) os.DirEntry {
return fsedsl.FileEntry(name, mode)
}
// DirEntry returns a synthetic directory DirEntry.
func DirEntry(name string, mode os.FileMode) os.DirEntry {
return fsedsl.DirEntry(name, mode)
}
// GenerateHelp produces help text from a filesystem spec tree.
func GenerateHelp(root FsNodeDecl) string {
return fsedsl.GenerateHelp(root)
} }

89
fs/handlers.go
View File

@ -42,69 +42,6 @@ var (
helpText string helpText string
) )
// GenerateHelp produces help text from a filesystem spec tree.
func GenerateHelp(root FsNodeDecl) string {
return generateHelp(root, "")
}
func generateHelp(node FsNodeDecl, prefix string) string {
var sb strings.Builder
path := node.Name
if prefix != "" {
path = prefix + "/" + node.Name
}
if node.Name == "/" {
path = ""
}
// Write this node's doc if it has one
if node.Desc != "" {
displayPath := path
if displayPath == "" {
displayPath = "/"
}
mode := node.Mode
if len(node.Children) > 0 || node.Bindings != nil {
mode = 0755 | os.ModeDir
}
fmt.Fprintf(&sb, "%-40s %s %s\n", displayPath, fmtMode(mode), node.Desc)
}
// Recurse into children
for _, child := range node.Children {
sb.WriteString(generateHelp(child, path))
}
return sb.String()
}
func fmtMode(m os.FileMode) string {
if m == 0 {
return "----"
}
var buf [4]byte
buf[0] = '-'
if m.IsDir() {
buf[0] = 'd'
}
buf[1] = 'r'
if m&0200 != 0 {
buf[1] = 'w'
}
if m&0400 != 0 {
buf[2] = 'r'
} else {
buf[2] = '-'
}
if m&0100 != 0 {
buf[3] = 'x'
} else {
buf[3] = '-'
}
return string(buf[:])
}
func readModels(ctx HandlerCtx) ([]byte, error) { func readModels(ctx HandlerCtx) ([]byte, error) {
if ctx.Models != nil { if ctx.Models != nil {
return ctx.Models.Get(), nil return ctx.Models.Get(), nil
@ -262,9 +199,13 @@ func elevateBindings(ctx HandlerCtx) ([]Binding, error) {
pending := ctx.Elevate.Pending() pending := ctx.Elevate.Pending()
out := make([]Binding, len(pending)) out := make([]Binding, len(pending))
for i, r := range pending { for i, r := range pending {
req := r // capture
out[i] = Binding{ out[i] = Binding{
Name: r.ID, Name: r.ID,
Data: r, Applier: func(c HandlerCtx) HandlerCtx {
c.Data = req
return c
},
} }
} }
return out, nil return out, nil
@ -323,7 +264,12 @@ func sessionBindings(_ HandlerCtx) ([]Binding, error) {
Aliases: []string{s.RunnableID()}, Aliases: []string{s.RunnableID()},
UID: s.Uname(), UID: s.Uname(),
GID: "agent", GID: "agent",
Session: s, Applier: func(c HandlerCtx) HandlerCtx {
c.Session = s
c.Remove = func() { Kill(rs, s.Name()) }
c.Rename = func(newName string) error { return Rename(rs, s.Name(), newName) }
return c
},
Remove: func() { Kill(rs, s.Name()) }, Remove: func() { Kill(rs, s.Name()) },
Rename: func(newName string) error { return Rename(rs, s.Name(), newName) }, Rename: func(newName string) error { return Rename(rs, s.Name(), newName) },
}) })
@ -454,8 +400,11 @@ func agentBindings(ctx HandlerCtx) ([]Binding, error) {
Aliases: []string{a.ID()}, Aliases: []string{a.ID()},
UID: a.ID(), UID: a.ID(),
GID: "agent", GID: "agent",
Agent: a, Applier: func(c HandlerCtx) HandlerCtx {
AgentLog: al, c.Agent = a
c.AgentLog = al
return c
},
Rename: func(newName string) error { Rename: func(newName string) error {
a.SetName(newName) a.SetName(newName)
persistSession(globalRootState, sess.Name()) persistSession(globalRootState, sess.Name())
@ -808,9 +757,13 @@ func processBindings(ctx HandlerCtx) ([]Binding, error) {
procs := ctx.Agent.ListDetached() procs := ctx.Agent.ListDetached()
out := make([]Binding, len(procs)) out := make([]Binding, len(procs))
for i, p := range procs { for i, p := range procs {
pid := p.PID // capture
out[i] = Binding{ out[i] = Binding{
Name: strconv.Itoa(p.PID), Name: strconv.Itoa(p.PID),
Data: p.PID, Applier: func(c HandlerCtx) HandlerCtx {
c.Data = pid
return c
},
} }
} }
return out, nil return out, nil

675
fsedsl/LICENSE.md Normal file
View File

@ -0,0 +1,675 @@
# GNU GENERAL PUBLIC LICENSE
Version 3, 29 June 2007
Copyright (C) 2007 Free Software Foundation, Inc.
<https://fsf.org/>
Everyone is permitted to copy and distribute verbatim copies of this
license document, but changing it is not allowed.
## Preamble
The GNU General Public License is a free, copyleft license for
software and other kinds of works.
The licenses for most software and other practical works are designed
to take away your freedom to share and change the works. By contrast,
the GNU General Public License is intended to guarantee your freedom
to share and change all versions of a program--to make sure it remains
free software for all its users. We, the Free Software Foundation, use
the GNU General Public License for most of our software; it applies
also to any other work released this way by its authors. You can apply
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When we speak of free software, we are referring to freedom, not
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To protect your rights, we need to prevent others from denying you
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For example, if you distribute copies of such a program, whether
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Developers that use the GNU GPL protect your rights with two steps:
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For the developers' and authors' protection, the GPL clearly explains
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### 7. Additional Terms.
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### 8. Termination.
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### 9. Acceptance Not Required for Having Copies.
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### 11. Patents.
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A contributor's "essential patent claims" are all patent claims owned
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Nothing in this License shall be construed as excluding or limiting
any implied license or other defenses to infringement that may
otherwise be available to you under applicable patent law.
### 12. No Surrender of Others' Freedom.
If conditions are imposed on you (whether by court order, agreement or
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terms that obligate you to collect a royalty for further conveying
from those to whom you convey the Program, the only way you could
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from conveying the Program.
### 13. Use with the GNU Affero General Public License.
Notwithstanding any other provision of this License, you have
permission to link or combine any covered work with a work licensed
under version 3 of the GNU Affero General Public License into a single
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License will continue to apply to the part which is the covered work,
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section 13, concerning interaction through a network will apply to the
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### 14. Revised Versions of this License.
The Free Software Foundation may publish revised and/or new versions
of the GNU General Public License from time to time. Such new versions
will be similar in spirit to the present version, but may differ in
detail to address new problems or concerns.
Each version is given a distinguishing version number. If the Program
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of any later version published by the Free Software Foundation. If the
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Software Foundation.
If the Program specifies that a proxy can decide which future versions
of the GNU General Public License can be used, that proxy's public
statement of acceptance of a version permanently authorizes you to
choose that version for the Program.
Later license versions may give you additional or different
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author or copyright holder as a result of your choosing to follow a
later version.
### 15. Disclaimer of Warranty.
THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT
WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE
DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR
CORRECTION.
### 16. Limitation of Liability.
IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR
CONVEYS THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES
ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT
NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR
LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM
TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER
PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
### 17. Interpretation of Sections 15 and 16.
If the disclaimer of warranty and limitation of liability provided
above cannot be given local legal effect according to their terms,
reviewing courts shall apply local law that most closely approximates
an absolute waiver of all civil liability in connection with the
Program, unless a warranty or assumption of liability accompanies a
copy of the Program in return for a fee.
END OF TERMS AND CONDITIONS
## How to Apply These Terms to Your New Programs
If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these
terms.
To do so, attach the following notices to the program. It is safest to
attach them to the start of each source file to most effectively state
the exclusion of warranty; and each file should have at least the
"copyright" line and a pointer to where the full notice is found.
<one line to give the program's name and a brief idea of what it does.>
Copyright (C) <year> <name of author>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
Also add information on how to contact you by electronic and paper
mail.
If the program does terminal interaction, make it output a short
notice like this when it starts in an interactive mode:
<program> Copyright (C) <year> <name of author>
This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
This is free software, and you are welcome to redistribute it
under certain conditions; type `show c' for details.
The hypothetical commands \`show w' and \`show c' should show the
appropriate parts of the General Public License. Of course, your
program's commands might be different; for a GUI interface, you would
use an "about box".
You should also get your employer (if you work as a programmer) or
school, if any, to sign a "copyright disclaimer" for the program, if
necessary. For more information on this, and how to apply and follow
the GNU GPL, see <https://www.gnu.org/licenses/>.
The GNU General Public License does not permit incorporating your
program into proprietary programs. If your program is a subroutine
library, you may consider it more useful to permit linking proprietary
applications with the library. If this is what you want to do, use the
GNU Lesser General Public License instead of this License. But first,
please read <https://www.gnu.org/licenses/why-not-lgpl.html>.

127
fsedsl/README.md Normal file
View File

@ -0,0 +1,127 @@
# fsedsl
A Go library providing an embedded domain-specific language (EDSL) for declaring synthetic filesystems. Designed for building 9P namespaces where the entire structure is declared statically but populated dynamically at runtime.
## Features
- **Declarative filesystem specification**: Define your namespace structure with `DirNode`, `FileNode`, and `Each` constructors
- **Generic context propagation**: Type-safe context passing through the tree via `Binding.Applier`
- **Dynamic bindings**: `Each` nodes iterate over runtime-determined collections
- **Auto-generated help**: `GenerateHelp` produces documentation from `Doc()` annotations
- **Standard filesystem semantics**: Implements read, write, stat, list, create, delete, rename
## Installation
```bash
go get git.lneely.de/lkn/fsedsl
```
## Quick Example
```go
package main
import (
"fmt"
"git.lneely.de/lkn/fsedsl"
)
type Ctx struct {
User *User
}
type User struct {
ID string
Name string
}
var users = []*User{
{ID: "1", Name: "alice"},
{ID: "2", Name: "bob"},
}
func main() {
spec := fsedsl.DirNode[Ctx]("/",
fsedsl.FileNode[Ctx]("version", 0444,
fsedsl.Doc[Ctx]("API version"),
fsedsl.Read(func(ctx Ctx) ([]byte, error) {
return []byte("1.0\n"), nil
}),
),
fsedsl.Each("{user}", func(ctx Ctx) ([]fsedsl.Binding[Ctx], error) {
var out []fsedsl.Binding[Ctx]
for _, u := range users {
user := u // capture
out = append(out, fsedsl.Binding[Ctx]{
Name: user.Name,
Aliases: []string{user.ID},
Applier: func(c Ctx) Ctx {
c.User = user
return c
},
})
}
return out, nil
},
fsedsl.FileNode[Ctx]("id", 0444,
fsedsl.Read(func(ctx Ctx) ([]byte, error) {
return []byte(ctx.User.ID + "\n"), nil
}),
),
fsedsl.FileNode[Ctx]("name", 0666,
fsedsl.Read(func(ctx Ctx) ([]byte, error) {
return []byte(ctx.User.Name + "\n"), nil
}),
),
),
)
tree := fsedsl.BuildTree(spec, Ctx{})
// List root
entries, _ := tree.List()
for _, e := range entries {
fmt.Println(e.Name())
}
// Read a file
f, _ := tree.Open("alice/name")
data, _ := f.Read()
fmt.Printf("alice/name: %s", data)
}
```
## API Overview
### Constructors
- `DirNode[Ctx](name, children/options...)` — static directory
- `FileNode[Ctx](name, mode, options...)` — file with handlers
- `Each[Ctx](pattern, bindingsFn, children/options...)` — dynamic directory template
### Options
- `Read(fn)` — read handler
- `Write(fn)` — write handler
- `Stream(fn)` — streaming read (blocks indefinitely)
- `BlockOnce(fn)` — blocking read (returns once)
- `Request(fn)` — request/response pattern (rdwr)
- `Doc(desc)` — human-readable description
- `UID(uid)`, `GID(gid)` — ownership
- `Alias(names...)` — alternate lookup names
### Building
```go
tree := fsedsl.BuildTree(spec, rootCtx)
```
### Help Generation
```go
help := fsedsl.GenerateHelp(spec)
```
## License
GPLv3

93
fs/builder.go → fsedsl/builder.go
View File

@ -1,4 +1,4 @@
package fs package fsedsl
import ( import (
"context" "context"
@ -9,7 +9,7 @@ import (
// BuildTree walks an FsNodeDecl spec and produces a *Tree. // BuildTree walks an FsNodeDecl spec and produces a *Tree.
// It validates the spec, resolves inheritance, and wires handlers. // It validates the spec, resolves inheritance, and wires handlers.
func BuildTree(spec FsNodeDecl, rootCtx HandlerCtx) *Tree { func BuildTree[Ctx any](spec FsNodeDecl[Ctx], rootCtx Ctx) *Tree {
validate(&spec, "") validate(&spec, "")
tree := build(&spec, "", "", rootCtx) tree := build(&spec, "", "", rootCtx)
return tree return tree
@ -17,7 +17,7 @@ func BuildTree(spec FsNodeDecl, rootCtx HandlerCtx) *Tree {
// ── validation ─────────────────────────────────────────────────── // ── validation ───────────────────────────────────────────────────
func validate(d *FsNodeDecl, path string) { func validate[Ctx any](d *FsNodeDecl[Ctx], path string) {
hasChildren := len(d.Children) > 0 hasChildren := len(d.Children) > 0
hasBindings := d.Bindings != nil hasBindings := d.Bindings != nil
hasFileHandlers := d.Read != nil || d.Write != nil || d.BlockOnce != nil || d.Stream != nil || d.Request != nil hasFileHandlers := d.Read != nil || d.Write != nil || d.BlockOnce != nil || d.Stream != nil || d.Request != nil
@ -78,7 +78,7 @@ func validate(d *FsNodeDecl, path string) {
// build ──────────────────────────────────────────────────────── // build ────────────────────────────────────────────────────────
func build(d *FsNodeDecl, parentUid, parentGid string, parentCtx HandlerCtx) *Tree { func build[Ctx any](d *FsNodeDecl[Ctx], parentUid, parentGid string, parentCtx Ctx) *Tree {
// Resolve inheritance. // Resolve inheritance.
uid := d.UID uid := d.UID
if uid == "" { if uid == "" {
@ -144,7 +144,7 @@ func build(d *FsNodeDecl, parentUid, parentGid string, parentCtx HandlerCtx) *Tr
// ── directory ops ──────────────────────────────────────────────── // ── directory ops ────────────────────────────────────────────────
func listDir(d *FsNodeDecl, uid, gid string, ctx HandlerCtx) ([]os.DirEntry, error) { func listDir[Ctx any](d *FsNodeDecl[Ctx], uid, gid string, ctx Ctx) ([]os.DirEntry, error) {
// Static directories: return static children and also resolve // Static directories: return static children and also resolve
// template/blueprint children for dynamic entries. // template/blueprint children for dynamic entries.
var entries []os.DirEntry var entries []os.DirEntry
@ -189,7 +189,7 @@ func listDir(d *FsNodeDecl, uid, gid string, ctx HandlerCtx) ([]os.DirEntry, err
return entries, nil return entries, nil
} }
func readdirDir(d *FsNodeDecl, uid, gid, name string, ctx HandlerCtx) ([]os.DirEntry, error) { func readdirDir[Ctx any](d *FsNodeDecl[Ctx], uid, gid, name string, ctx Ctx) ([]os.DirEntry, error) {
child, childCtx := findChild(d, name, ctx) child, childCtx := findChild(d, name, ctx)
if child == nil { if child == nil {
return nil, fmt.Errorf("%s: not found", name) return nil, fmt.Errorf("%s: not found", name)
@ -197,7 +197,7 @@ func readdirDir(d *FsNodeDecl, uid, gid, name string, ctx HandlerCtx) ([]os.DirE
return listDir(child, resolveUID(child, uid), resolveGID(child, gid), childCtx) return listDir(child, resolveUID(child, uid), resolveGID(child, gid), childCtx)
} }
func statDir(d *FsNodeDecl, uid, gid, name string, ctx HandlerCtx) (os.FileInfo, error) { func statDir[Ctx any](d *FsNodeDecl[Ctx], uid, gid, name string, ctx Ctx) (os.FileInfo, error) {
// Stat of the dir itself. // Stat of the dir itself.
if name == "" || name == "." { if name == "" || name == "." {
m := d.Mode m := d.Mode
@ -228,7 +228,7 @@ func statDir(d *FsNodeDecl, uid, gid, name string, ctx HandlerCtx) (os.FileInfo,
return &SyntheticFileInfo{Name_: name, Mode_: cm, UID_: cu, GID_: cg}, nil return &SyntheticFileInfo{Name_: name, Mode_: cm, UID_: cu, GID_: cg}, nil
} }
func openDir(d *FsNodeDecl, uid, gid string, name string, ctx HandlerCtx) (File, error) { func openDir[Ctx any](d *FsNodeDecl[Ctx], uid, gid string, name string, ctx Ctx) (File, error) {
child, childCtx := findChild(d, name, ctx) child, childCtx := findChild(d, name, ctx)
if child == nil { if child == nil {
return nil, fmt.Errorf("%s: not found", name) return nil, fmt.Errorf("%s: not found", name)
@ -237,7 +237,7 @@ func openDir(d *FsNodeDecl, uid, gid string, name string, ctx HandlerCtx) (File,
return sub.Open("") return sub.Open("")
} }
func deleteDir(d *FsNodeDecl, name string, ctx HandlerCtx) error { func deleteDir[Ctx any](d *FsNodeDecl[Ctx], name string, ctx Ctx) error {
child, childCtx := findChild(d, name, ctx) child, childCtx := findChild(d, name, ctx)
if child == nil { if child == nil {
return fmt.Errorf("%s: not found", name) return fmt.Errorf("%s: not found", name)
@ -248,7 +248,7 @@ func deleteDir(d *FsNodeDecl, name string, ctx HandlerCtx) error {
return fmt.Errorf("%s: not removable", name) return fmt.Errorf("%s: not removable", name)
} }
func renameDir(d *FsNodeDecl, old, new string, ctx HandlerCtx) error { func renameDir[Ctx any](d *FsNodeDecl[Ctx], old, new string, ctx Ctx) error {
child, _ := findChild(d, old, ctx) child, _ := findChild(d, old, ctx)
if child == nil { if child == nil {
return fmt.Errorf("%s: not found", old) return fmt.Errorf("%s: not found", old)
@ -261,7 +261,7 @@ func renameDir(d *FsNodeDecl, old, new string, ctx HandlerCtx) error {
// ── leaf ops ───────────────────────────────────────────────────── // ── leaf ops ─────────────────────────────────────────────────────
func openLeaf(d *FsNodeDecl, uid, gid string, mode os.FileMode, ctx HandlerCtx, name string) (File, error) { func openLeaf[Ctx any](d *FsNodeDecl[Ctx], uid, gid string, mode os.FileMode, ctx Ctx, name string) (File, error) {
notBlocking := func(context.Context, string) ([]byte, string, error) { notBlocking := func(context.Context, string) ([]byte, string, error) {
return nil, "", fmt.Errorf("blocking read not supported") return nil, "", fmt.Errorf("blocking read not supported")
} }
@ -342,7 +342,7 @@ func openLeaf(d *FsNodeDecl, uid, gid string, mode os.FileMode, ctx HandlerCtx,
// ── helpers ────────────────────────────────────────────────────── // ── helpers ──────────────────────────────────────────────────────
func findChild(d *FsNodeDecl, name string, ctx HandlerCtx) (*FsNodeDecl, HandlerCtx) { func findChild[Ctx any](d *FsNodeDecl[Ctx], name string, ctx Ctx) (*FsNodeDecl[Ctx], Ctx) {
// Handle nested paths recursively. // Handle nested paths recursively.
if i := strings.IndexByte(name, '/'); i >= 0 { if i := strings.IndexByte(name, '/'); i >= 0 {
prefix := name[:i] prefix := name[:i]
@ -372,7 +372,10 @@ func findChild(d *FsNodeDecl, name string, ctx HandlerCtx) (*FsNodeDecl, Handler
if b.Name == name || matchAlias(b.Aliases, name) { if b.Name == name || matchAlias(b.Aliases, name) {
// Clone the blueprint with binding identity and apply context. // Clone the blueprint with binding identity and apply context.
clone := cloneBlueprint(&d.Children[i], b) clone := cloneBlueprint(&d.Children[i], b)
boundCtx := applyBinding(ctx, b, d.Children[i].BindTargets) boundCtx := ctx
if b.Applier != nil {
boundCtx = b.Applier(ctx)
}
return clone, boundCtx return clone, boundCtx
} }
} }
@ -383,7 +386,7 @@ func findChild(d *FsNodeDecl, name string, ctx HandlerCtx) (*FsNodeDecl, Handler
} }
// cloneBlueprint creates a copy of the blueprint with binding identity applied. // cloneBlueprint creates a copy of the blueprint with binding identity applied.
func cloneBlueprint(bp *FsNodeDecl, b Binding) *FsNodeDecl { func cloneBlueprint[Ctx any](bp *FsNodeDecl[Ctx], b Binding[Ctx]) *FsNodeDecl[Ctx] {
clone := *bp clone := *bp
clone.Name = b.Name clone.Name = b.Name
clone.Aliases = b.Aliases clone.Aliases = b.Aliases
@ -399,64 +402,6 @@ func cloneBlueprint(bp *FsNodeDecl, b Binding) *FsNodeDecl {
return &clone return &clone
} }
// applyBinding populates the HandlerCtx with binding data based on BindTargets.
// If no targets are specified, all non-nil fields are applied (legacy behavior).
func applyBinding(ctx HandlerCtx, b Binding, targets []BindTarget) HandlerCtx {
if len(targets) == 0 {
// Legacy: apply all non-nil fields.
if b.Session != nil {
ctx.Session = b.Session
}
if b.Agent != nil {
ctx.Agent = b.Agent
}
if b.AgentLog != nil {
ctx.AgentLog = b.AgentLog
}
if b.Data != nil {
ctx.Data = b.Data
}
if b.Remove != nil {
ctx.Remove = b.Remove
}
if b.Rename != nil {
ctx.Rename = b.Rename
}
return ctx
}
// Apply only specified targets.
for _, t := range targets {
switch t {
case BindSession:
if b.Session != nil {
ctx.Session = b.Session
}
case BindAgent:
if b.Agent != nil {
ctx.Agent = b.Agent
}
case BindAgentLog:
if b.AgentLog != nil {
ctx.AgentLog = b.AgentLog
}
case BindData:
if b.Data != nil {
ctx.Data = b.Data
}
case BindRemove:
if b.Remove != nil {
ctx.Remove = b.Remove
}
case BindRename:
if b.Rename != nil {
ctx.Rename = b.Rename
}
}
}
return ctx
}
func matchAlias(aliases []string, name string) bool { func matchAlias(aliases []string, name string) bool {
for _, a := range aliases { for _, a := range aliases {
if a == name { if a == name {
@ -466,14 +411,14 @@ func matchAlias(aliases []string, name string) bool {
return false return false
} }
func resolveUID(d *FsNodeDecl, parent string) string { func resolveUID[Ctx any](d *FsNodeDecl[Ctx], parent string) string {
if d.UID != "" { if d.UID != "" {
return d.UID return d.UID
} }
return parent return parent
} }
func resolveGID(d *FsNodeDecl, parent string) string { func resolveGID[Ctx any](d *FsNodeDecl[Ctx], parent string) string {
if d.GID != "" { if d.GID != "" {
return d.GID return d.GID
} }

224
fsedsl/decl.go Normal file
View File

@ -0,0 +1,224 @@
// Package fsedsl provides an embedded domain-specific language for declaring
// synthetic filesystems. It is designed for building 9P namespaces where the
// entire filesystem structure is declared statically but populated dynamically.
//
// The core type is FsNodeDecl[Ctx], a recursive structure that describes
// directories, files, and template nodes (Each). Handlers receive a context
// of type Ctx, allowing domain-specific data to flow through the tree.
//
// Example usage:
//
// type MyCtx struct {
// User *User
// Data any
// }
//
// spec := DirNode[MyCtx]("/",
// FileNode[MyCtx]("version", 0444,
// Doc("API version"),
// Read(func(ctx MyCtx) ([]byte, error) {
// return []byte("1.0\n"), nil
// }),
// ),
// Each[MyCtx]("{user}", userBindings,
// FileNode[MyCtx]("name", 0444,
// Read(func(ctx MyCtx) ([]byte, error) {
// return []byte(ctx.User.Name + "\n"), nil
// }),
// ),
// ),
// )
//
// tree := BuildTree(spec, MyCtx{})
package fsedsl
import (
"context"
"os"
)
// FsNodeDecl describes one node in a filesystem namespace.
// The entire filesystem is a single recursive tree of these declarations.
// Ctx is the context type passed to all handler functions.
type FsNodeDecl[Ctx any] struct {
// Identity.
Name string
Aliases []string // alternate names that resolve to this node (e.g. immutable ID)
UID string // "" = inherit from parent
GID string // "" = inherit from parent
Mode os.FileMode // 0 = inherit parent default
Desc string // human-readable description
// Tstat — metadata override (non-nil bypasses Name/UID/GID/Mode/size defaulting).
Stat func() os.FileInfo
// Twalk — children (implies directory; at most one set).
Children []FsNodeDecl[Ctx] // static, known at compile time
Bindings func(Ctx) ([]Binding[Ctx], error) // Each bindings
BindTargets []BindTarget // declares what Bindings provides
// Tread (non-blocking) + Twrite.
Read func(ctx Ctx) ([]byte, error)
Write func(ctx Ctx, data []byte) error
// Tread — blocking variants (at most one set).
BlockOnce func(ctx Ctx, cctx context.Context, base string) ([]byte, string, error)
Stream func(ctx Ctx, cctx context.Context, base string) ([]byte, string, error)
// Request — rdwr: write triggers result, read returns it once.
Request func(ctx Ctx, data []byte) ([]byte, error)
// Tcreate + Tremove + Trename (directory ops).
Create func(ctx Ctx, name string) error
Remove func(ctx Ctx) error
Rename func(newName string) error
}
// NodeOption configures a FsNodeDecl at construction time.
type NodeOption[Ctx any] func(*FsNodeDecl[Ctx])
// Binding provides identity and data for one iteration of Each.
// The structure is cloned for each binding, and handlers receive
// the bound data via the Ctx fields specified by BindTargets.
type Binding[Ctx any] struct {
Name string // directory/file name (e.g. session name, agent name)
Aliases []string // alternate lookup names (e.g. immutable ID)
UID string // owner (empty = inherit)
GID string // group (empty = inherit)
// Applier updates the context with bound data.
// Called when traversing into this binding's node.
Applier func(ctx Ctx) Ctx
// Lifecycle callbacks.
Remove func()
Rename func(string) error
}
// BindTarget declares what data an Each block binds to handlers.
// This is advisory — the actual binding is done by Binding.Applier.
type BindTarget int
const (
BindData BindTarget = iota // generic data binding
)
// ── EDSL constructors ────────────────────────────────────────────
// DirNode declares a static directory node.
// Arguments can be FsNodeDecl[Ctx] children or NodeOption[Ctx] modifiers.
func DirNode[Ctx any](name string, args ...any) FsNodeDecl[Ctx] {
d := FsNodeDecl[Ctx]{Name: name}
for _, a := range args {
switch v := a.(type) {
case FsNodeDecl[Ctx]:
d.Children = append(d.Children, v)
case NodeOption[Ctx]:
v(&d)
}
}
return d
}
// Each declares a directory that is instantiated for each binding in a collection.
// The bindings function is called at list/traverse time to determine instances.
//
// Example:
//
// Each[MyCtx]("{id}", func(ctx MyCtx) ([]Binding[MyCtx], error) {
// return []Binding[MyCtx]{
// {Name: "foo", Applier: func(c MyCtx) MyCtx { c.Data = "foo"; return c }},
// }, nil
// },
// FileNode[MyCtx]("name", 0444, Read(readName)),
// )
func Each[Ctx any](name string, bindings func(Ctx) ([]Binding[Ctx], error), args ...any) FsNodeDecl[Ctx] {
d := FsNodeDecl[Ctx]{Name: name, Bindings: bindings}
for _, a := range args {
switch v := a.(type) {
case FsNodeDecl[Ctx]:
d.Children = append(d.Children, v)
case NodeOption[Ctx]:
v(&d)
}
}
return d
}
// FileNode declares a file node (non-directory).
func FileNode[Ctx any](name string, mode os.FileMode, opts ...NodeOption[Ctx]) FsNodeDecl[Ctx] {
d := FsNodeDecl[Ctx]{Name: name, Mode: mode}
for _, o := range opts {
o(&d)
}
return d
}
// ── Options ──────────────────────────────────────────────────────
// Read sets the read handler for a file node.
func Read[Ctx any](fn func(Ctx) ([]byte, error)) NodeOption[Ctx] {
return func(d *FsNodeDecl[Ctx]) { d.Read = fn }
}
// Write sets the write handler for a file node.
func Write[Ctx any](fn func(Ctx, []byte) error) NodeOption[Ctx] {
return func(d *FsNodeDecl[Ctx]) { d.Write = fn }
}
// Stream sets a streaming read handler that blocks indefinitely.
func Stream[Ctx any](fn func(Ctx, context.Context, string) ([]byte, string, error)) NodeOption[Ctx] {
return func(d *FsNodeDecl[Ctx]) { d.Stream = fn }
}
// BlockOnce sets a blocking read handler that returns once.
func BlockOnce[Ctx any](fn func(Ctx, context.Context, string) ([]byte, string, error)) NodeOption[Ctx] {
return func(d *FsNodeDecl[Ctx]) { d.BlockOnce = fn }
}
// Request sets a request-response handler (rdwr pattern).
func Request[Ctx any](fn func(Ctx, []byte) ([]byte, error)) NodeOption[Ctx] {
return func(d *FsNodeDecl[Ctx]) { d.Request = fn }
}
// CreateFile sets the file creation handler for a directory node.
func CreateFile[Ctx any](fn func(Ctx, string) error) NodeOption[Ctx] {
return func(d *FsNodeDecl[Ctx]) { d.Create = fn }
}
// RemoveNode sets the removal handler for a node.
func RemoveNode[Ctx any](fn func(Ctx) error) NodeOption[Ctx] {
return func(d *FsNodeDecl[Ctx]) { d.Remove = fn }
}
// StatOverride sets a custom stat handler that bypasses default metadata.
func StatOverride[Ctx any](fn func() os.FileInfo) NodeOption[Ctx] {
return func(d *FsNodeDecl[Ctx]) { d.Stat = fn }
}
// UID sets the owner for a node.
func UID[Ctx any](uid string) NodeOption[Ctx] {
return func(d *FsNodeDecl[Ctx]) { d.UID = uid }
}
// GID sets the group for a node.
func GID[Ctx any](gid string) NodeOption[Ctx] {
return func(d *FsNodeDecl[Ctx]) { d.GID = gid }
}
// Alias adds alternate names for resolving this node.
func Alias[Ctx any](names ...string) NodeOption[Ctx] {
return func(d *FsNodeDecl[Ctx]) { d.Aliases = append(d.Aliases, names...) }
}
// Bind declares how Each bindings populate the context.
// This is advisory metadata; the actual binding is done by Binding.Applier.
func Bind[Ctx any](targets ...BindTarget) NodeOption[Ctx] {
return func(d *FsNodeDecl[Ctx]) { d.BindTargets = append(d.BindTargets, targets...) }
}
// Doc sets a human-readable description for the node.
// Used by GenerateHelp to produce documentation.
func Doc[Ctx any](desc string) NodeOption[Ctx] {
return func(d *FsNodeDecl[Ctx]) { d.Desc = desc }
}

295
fsedsl/decl_test.go Normal file
View File

@ -0,0 +1,295 @@
package fsedsl
import (
"os"
"testing"
)
// TestCtx is a simple test context.
type TestCtx struct {
Data any
}
// TestEachBasic tests the basic Blueprint pattern:
// - Declares structure statically
// - Bindings function provides identity (name, aliases, UID/GID)
// - Handlers receive context with bound data
func TestEachBasic(t *testing.T) {
type testData struct {
ID string
Name string
}
instances := []testData{
{ID: "aaa-111", Name: "first"},
{ID: "bbb-222", Name: "second"},
}
spec := DirNode[TestCtx]("/",
Each("{id}", func(ctx TestCtx) ([]Binding[TestCtx], error) {
var out []Binding[TestCtx]
for _, d := range instances {
data := d // capture
out = append(out, Binding[TestCtx]{
Name: data.Name,
Aliases: []string{data.ID},
UID: data.ID,
GID: "testgroup",
})
}
return out, nil
},
FileNode[TestCtx]("id", 0444, Read(func(ctx TestCtx) ([]byte, error) {
return []byte("test-id\n"), nil
})),
FileNode[TestCtx]("name", 0666,
Read(func(ctx TestCtx) ([]byte, error) {
return []byte("test-name\n"), nil
}),
Write(func(ctx TestCtx, data []byte) error {
return nil // no-op for test
}),
),
),
)
tree := BuildTree(spec, TestCtx{})
// Test: List root should show the two instances by name
entries, err := tree.List()
if err != nil {
t.Fatalf("List root: %v", err)
}
if len(entries) != 2 {
t.Errorf("List root: got %d entries, want 2", len(entries))
}
names := make(map[string]bool)
for _, e := range entries {
names[e.Name()] = true
}
if !names["first"] {
t.Error("List root: missing 'first'")
}
if !names["second"] {
t.Error("List root: missing 'second'")
}
// Test: Access by name
sub, err := tree.Readdir("first")
if err != nil {
t.Fatalf("Readdir(first): %v", err)
}
foundID := false
foundName := false
for _, e := range sub {
switch e.Name() {
case "id":
foundID = true
case "name":
foundName = true
}
}
if !foundID {
t.Error("Readdir(first): missing 'id' leaf")
}
if !foundName {
t.Error("Readdir(first): missing 'name' leaf")
}
// Test: Access by alias
subByAlias, err := tree.Readdir("aaa-111")
if err != nil {
t.Fatalf("Readdir(aaa-111): %v", err)
}
if len(subByAlias) != len(sub) {
t.Errorf("Readdir by alias: got %d entries, want %d", len(subByAlias), len(sub))
}
// Test: Read leaf file
f, err := tree.Open("first/id")
if err != nil {
t.Fatalf("Open(first/id): %v", err)
}
data, err := f.Read()
if err != nil {
t.Fatalf("Read(first/id): %v", err)
}
if string(data) != "test-id\n" {
t.Errorf("Read(first/id) = %q, want %q", data, "test-id\n")
}
// Test: Stat instance directory
fi, err := tree.Stat("first")
if err != nil {
t.Fatalf("Stat(first): %v", err)
}
if !fi.IsDir() {
t.Error("Stat(first): expected directory")
}
if fi.Name() != "first" {
t.Errorf("Stat(first).Name() = %q, want 'first'", fi.Name())
}
// Test: Stat via alias
fiAlias, err := tree.Stat("aaa-111")
if err != nil {
t.Fatalf("Stat(aaa-111): %v", err)
}
if fiAlias.Name() != "aaa-111" {
t.Errorf("Stat(aaa-111).Name() = %q, want 'aaa-111'", fiAlias.Name())
}
}
// TestContextApplier tests that Binding.Applier correctly propagates context
func TestContextApplier(t *testing.T) {
type Ctx struct {
UserID string
}
spec := DirNode[Ctx]("/",
Each("{user}", func(ctx Ctx) ([]Binding[Ctx], error) {
return []Binding[Ctx]{
{
Name: "alice",
Applier: func(c Ctx) Ctx {
c.UserID = "alice-123"
return c
},
},
{
Name: "bob",
Applier: func(c Ctx) Ctx {
c.UserID = "bob-456"
return c
},
},
}, nil
},
FileNode[Ctx]("whoami", 0444, Read(func(ctx Ctx) ([]byte, error) {
return []byte(ctx.UserID + "\n"), nil
})),
),
)
tree := BuildTree(spec, Ctx{})
// Test: Read alice's whoami
f, err := tree.Open("alice/whoami")
if err != nil {
t.Fatalf("Open(alice/whoami): %v", err)
}
data, err := f.Read()
if err != nil {
t.Fatalf("Read: %v", err)
}
if string(data) != "alice-123\n" {
t.Errorf("alice/whoami = %q, want 'alice-123\\n'", data)
}
// Test: Read bob's whoami
f2, err := tree.Open("bob/whoami")
if err != nil {
t.Fatalf("Open(bob/whoami): %v", err)
}
data2, err := f2.Read()
if err != nil {
t.Fatalf("Read: %v", err)
}
if string(data2) != "bob-456\n" {
t.Errorf("bob/whoami = %q, want 'bob-456\\n'", data2)
}
}
// TestGenerateHelp tests help generation
func TestGenerateHelp(t *testing.T) {
spec := DirNode[TestCtx]("/",
FileNode[TestCtx]("version", 0444,
Doc[TestCtx]("API version"),
Read(func(ctx TestCtx) ([]byte, error) {
return []byte("1.0\n"), nil
}),
),
DirNode[TestCtx]("data",
Doc[TestCtx]("Data directory"),
FileNode[TestCtx]("config", 0666,
Doc[TestCtx]("Configuration file"),
),
),
)
help := GenerateHelp(spec)
if help == "" {
t.Error("GenerateHelp returned empty string")
}
if !contains(help, "version") {
t.Error("help missing 'version'")
}
if !contains(help, "API version") {
t.Error("help missing 'API version' description")
}
if !contains(help, "data") {
t.Error("help missing 'data'")
}
}
func contains(s, substr string) bool {
return len(s) >= len(substr) && (s == substr || len(s) > 0 && containsAt(s, substr))
}
func containsAt(s, substr string) bool {
for i := 0; i <= len(s)-len(substr); i++ {
if s[i:i+len(substr)] == substr {
return true
}
}
return false
}
// TestStatMode tests file modes are preserved
func TestStatMode(t *testing.T) {
spec := DirNode[TestCtx]("/",
Each("{id}", func(ctx TestCtx) ([]Binding[TestCtx], error) {
return []Binding[TestCtx]{{Name: "instance"}}, nil
},
FileNode[TestCtx]("readable", 0444, Read(func(ctx TestCtx) ([]byte, error) {
return []byte("r\n"), nil
})),
FileNode[TestCtx]("writable", 0666,
Read(func(ctx TestCtx) ([]byte, error) {
return []byte("rw\n"), nil
}),
Write(func(ctx TestCtx, data []byte) error {
return nil
}),
),
FileNode[TestCtx]("executable", 0555, Read(func(ctx TestCtx) ([]byte, error) {
return []byte("#!/bin/sh\n"), nil
})),
),
)
tree := BuildTree(spec, TestCtx{})
tests := []struct {
path string
mode os.FileMode
}{
{"instance", os.ModeDir | 0755},
{"instance/readable", 0444},
{"instance/writable", 0666},
{"instance/executable", 0555},
}
for _, tc := range tests {
fi, err := tree.Stat(tc.path)
if err != nil {
t.Errorf("Stat(%q): %v", tc.path, err)
continue
}
if fi.Mode() != tc.mode {
t.Errorf("Stat(%q).Mode() = %o, want %o", tc.path, fi.Mode(), tc.mode)
}
}
}

21
fs/file.go → fsedsl/file.go
View File

@ -1,6 +1,4 @@
// Package fs defines the file tree interfaces and implementation. package fsedsl
// implementation used by the 9P server.
package fs
import ( import (
"context" "context"
@ -34,15 +32,6 @@ type FileTree interface {
Rename(oldName, newName string) error Rename(oldName, newName string) error
} }
// Runnable is a running agent that can be observed and controlled.
type Runnable interface {
RunnableID() string
Cancel()
Interrupt()
AppendLog([]byte)
LogInfo() (length int, vers uint32)
}
// FileConfig implements File via function pointers. // FileConfig implements File via function pointers.
type FileConfig struct { type FileConfig struct {
StatFn func() (os.FileInfo, error) StatFn func() (os.FileInfo, error)
@ -127,3 +116,11 @@ func FileEntry(name string, mode os.FileMode) os.DirEntry {
func DirEntry(name string, mode os.FileMode) os.DirEntry { func DirEntry(name string, mode os.FileMode) os.DirEntry {
return &SyntheticEntry{Name_: name, Mode_: mode, IsDir_: true} return &SyntheticEntry{Name_: name, Mode_: mode, IsDir_: true}
} }
// Structural permissions — used by Tree for mounted children and synthetic files.
const (
PermChildDir os.FileMode = 0555
PermIdx os.FileMode = 0444
PermMkdir os.FileMode = 0755
PermMkdirPrivate os.FileMode = 0700
)

3
fsedsl/go.mod Normal file
View File

@ -0,0 +1,3 @@
module ollie/fsedsl
go 1.25.6

71
fsedsl/help.go Normal file
View File

@ -0,0 +1,71 @@
package fsedsl
import (
"fmt"
"os"
"strings"
)
// GenerateHelp produces documentation from a filesystem spec tree.
// It walks the tree recursively and emits a line for each node with a Doc description.
func GenerateHelp[Ctx any](root FsNodeDecl[Ctx]) string {
return generateHelp(root, "")
}
func generateHelp[Ctx any](node FsNodeDecl[Ctx], prefix string) string {
var sb strings.Builder
path := node.Name
if prefix != "" {
path = prefix + "/" + node.Name
}
if node.Name == "/" {
path = ""
}
// Write this node's doc if it has one
if node.Desc != "" {
displayPath := path
if displayPath == "" {
displayPath = "/"
}
mode := node.Mode
if len(node.Children) > 0 || node.Bindings != nil {
mode = 0755 | os.ModeDir
}
fmt.Fprintf(&sb, "%-40s %s %s\n", displayPath, fmtMode(mode), node.Desc)
}
// Recurse into children
for _, child := range node.Children {
sb.WriteString(generateHelp(child, path))
}
return sb.String()
}
func fmtMode(m os.FileMode) string {
if m == 0 {
return "----"
}
var buf [4]byte
buf[0] = '-'
if m.IsDir() {
buf[0] = 'd'
}
buf[1] = 'r'
if m&0200 != 0 {
buf[1] = 'w'
}
if m&0400 != 0 {
buf[2] = 'r'
} else {
buf[2] = '-'
}
if m&0100 != 0 {
buf[3] = 'x'
} else {
buf[3] = '-'
}
return string(buf[:])
}

28
fs/tree.go → fsedsl/tree.go
View File

@ -1,4 +1,4 @@
package fs package fsedsl
import ( import (
"context" "context"
@ -28,61 +28,61 @@ type Tree struct {
Data any // user-attached state Data any // user-attached state
} }
// Option configures a Tree. // TreeOption configures a Tree.
type Option func(*Tree) type TreeOption func(*Tree)
// WithReadOnly makes the tree reject writes, creates, deletes, and renames. // WithReadOnly makes the tree reject writes, creates, deletes, and renames.
func WithReadOnly() Option { return func(d *Tree) { d.readOnly = true } } func WithReadOnly() TreeOption { return func(d *Tree) { d.readOnly = true } }
// WithIndex adds a synthetic read-only "idx" entry whose content is // WithIndex adds a synthetic read-only "idx" entry whose content is
// generated by calling fn with the tree itself. // generated by calling fn with the tree itself.
func WithIndex(fn func(FileTree) ([]byte, error)) Option { func WithIndex(fn func(FileTree) ([]byte, error)) TreeOption {
return func(d *Tree) { d.indexFn = fn } return func(d *Tree) { d.indexFn = fn }
} }
// WithResolver overrides how virtual names map to filesystem paths. // WithResolver overrides how virtual names map to filesystem paths.
func WithResolver(fn func(dirs []string, name string) (string, error)) Option { func WithResolver(fn func(dirs []string, name string) (string, error)) TreeOption {
return func(d *Tree) { d.resolveFn = fn } return func(d *Tree) { d.resolveFn = fn }
} }
// WithLister overrides how the tree lists its entries. // WithLister overrides how the tree lists its entries.
func WithLister(fn func(dirs []string) ([]os.DirEntry, error)) Option { func WithLister(fn func(dirs []string) ([]os.DirEntry, error)) TreeOption {
return func(d *Tree) { d.listFn = fn } return func(d *Tree) { d.listFn = fn }
} }
// WithCreator overrides file creation logic. // WithCreator overrides file creation logic.
func WithCreator(fn func(dirs []string, name string, perm os.FileMode) error) Option { func WithCreator(fn func(dirs []string, name string, perm os.FileMode) error) TreeOption {
return func(d *Tree) { d.createFn = fn } return func(d *Tree) { d.createFn = fn }
} }
// WithDeleter overrides file deletion logic. // WithDeleter overrides file deletion logic.
func WithDeleter(fn func(dirs []string, name string) error) Option { func WithDeleter(fn func(dirs []string, name string) error) TreeOption {
return func(d *Tree) { d.deleteFn = fn } return func(d *Tree) { d.deleteFn = fn }
} }
// WithRenamer overrides rename logic. // WithRenamer overrides rename logic.
func WithRenamer(fn func(dirs []string, old, new string) error) Option { func WithRenamer(fn func(dirs []string, old, new string) error) TreeOption {
return func(d *Tree) { d.renameFn = fn } return func(d *Tree) { d.renameFn = fn }
} }
// WithOpener overrides how entries are opened (bypasses filesystem read). // WithOpener overrides how entries are opened (bypasses filesystem read).
func WithOpener(fn func(dirs []string, name string) (File, error)) Option { func WithOpener(fn func(dirs []string, name string) (File, error)) TreeOption {
return func(d *Tree) { d.openFn = fn } return func(d *Tree) { d.openFn = fn }
} }
// WithStat overrides how entries are stat'd. // WithStat overrides how entries are stat'd.
func WithStat(fn func(dirs []string, name string) (os.FileInfo, error)) Option { func WithStat(fn func(dirs []string, name string) (os.FileInfo, error)) TreeOption {
return func(d *Tree) { d.statFn = fn } return func(d *Tree) { d.statFn = fn }
} }
// WithReaddir overrides subdirectory listing. // WithReaddir overrides subdirectory listing.
func WithReaddir(fn func(dirs []string, name string) ([]os.DirEntry, error)) Option { func WithReaddir(fn func(dirs []string, name string) ([]os.DirEntry, error)) TreeOption {
return func(d *Tree) { d.readdirFn = fn } return func(d *Tree) { d.readdirFn = fn }
} }
// NewTree creates a Tree backed by one or more directories. // NewTree creates a Tree backed by one or more directories.
// The first directory is the write target for unions. // The first directory is the write target for unions.
func NewTree(dirs []string, perm os.FileMode, opts ...Option) *Tree { func NewTree(dirs []string, perm os.FileMode, opts ...TreeOption) *Tree {
d := &Tree{Tree: dirs, perm: perm} d := &Tree{Tree: dirs, perm: perm}
for _, o := range opts { for _, o := range opts {
o(d) o(d)

3
go.mod
View File

@ -9,6 +9,9 @@ require (
github.com/simonfxr/pubsub v0.0.5 github.com/simonfxr/pubsub v0.0.5
golang.org/x/time v0.15.0 golang.org/x/time v0.15.0
gopkg.in/yaml.v3 v3.0.1 gopkg.in/yaml.v3 v3.0.1
ollie/fsedsl v0.0.0
) )
require golang.org/x/sys v0.47.0 // indirect require golang.org/x/sys v0.47.0 // indirect
replace ollie/fsedsl => ./fsedsl