jochen
9cef820117
After the operator removes by hand what the last search found, no apply says so and nothing searched again until the next day. node setuid-search <node> signs the ask as a hand-over is, under its own context, on a subject only the node's engine hears and only the controller may publish.
200 lines
11 KiB
Go
200 lines
11 KiB
Go
package broker
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import (
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"fmt"
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"slices"
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"strings"
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)
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// The writers table (novox/hq to-be 45 §1, ADR 0227 rule 1), compiled in.
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//
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// **Every kind of state the core keeps has one writer; anyone else asks it.** The table is the design's,
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// row for row, with what each row writes on the bus where it writes there. Two things read it: the
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// composition of every principal's grants (PermissionsFor), which **refuses a grant that lets a
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// principal publish on a subject another writes** — so a second writer cannot be granted by accident,
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// and the composition says which state and whose — and the test beside it, which walks the rows
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// against the design's list and the composition of a whole mesh. Changing a writer is a change to
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// this table, through a decision.
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// WriterRow is one row of the writers table.
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type WriterRow struct {
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State string
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Writer string
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KeptIn string
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Others string
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// Subjects are the bus subjects a write of this state is a publish to; none for state kept off the
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// bus (the controller's store, a module's own) or not built yet.
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Subjects []string
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// Writes says a principal granted a publish pattern overlapping Subjects is this state's writer —
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// given the pattern, because a machine writes its own report and no other's.
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Writes func(p Principal, pattern string) bool
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// Shared says why more than one principal may publish here; empty for one writer.
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Shared string
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}
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// isController, and the other writers' tests, are who a row's writer is as a principal.
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func isController(p Principal, _ string) bool { return p.Kind == KindController }
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// ownMachine is a node writing a subject whose third token is its own name, and no wildcard there.
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func ownMachine(p Principal, pattern string) bool {
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tokens := strings.Split(pattern, ".")
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return p.Kind == KindNode && len(tokens) > 2 && tokens[2] == p.Node
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}
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// holdsSeatOf is a principal holding the seat a `mesh.seat.<seat>.…` pattern names: its module's own
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// principal, or the node tools carrying a module that holds it (ADR 0175, the runtime is its modules).
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func holdsSeatOf(p Principal, pattern string) bool {
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tokens := strings.Split(pattern, ".")
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if len(tokens) < 3 {
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return false
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}
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seat := tokens[2]
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holds := func(seats []Seat) bool {
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return slices.ContainsFunc(seats, func(s Seat) bool { return s.Name == seat })
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}
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switch p.Kind {
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case KindModule:
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return holds(p.Holds)
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case KindNodeTools:
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return slices.ContainsFunc(p.Carries, func(d Declared) bool { return holds(d.Holds) })
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}
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return false
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}
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// ownModule is a module publishing under its own name, or the node tools carrying it.
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func ownModule(p Principal, pattern string) bool {
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tokens := strings.Split(pattern, ".")
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if len(tokens) < 3 {
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return false
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}
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module := tokens[2]
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switch p.Kind {
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case KindModule:
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return p.Module == module
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case KindNodeTools:
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return slices.ContainsFunc(p.Carries, func(d Declared) bool { return d.Module == module })
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}
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return false
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}
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// kvOf is a bucket's write subjects.
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func kvOf(bucket string) []string { return []string{"$KV." + bucket + ".>"} }
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// WritersTable is to-be 45 §1, in its order.
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var WritersTable = []WriterRow{
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{State: "a machine's declaration", Writer: "controller (lease holder)", KeptIn: "the bus, last per subject",
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Others: "read", Subjects: []string{"mesh.node.*.declare"}, Writes: isController},
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// The operator's hand-over of a directory used as found, asked of the machine's engine at the controller's
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// terminal (novox/hq issue 356). One publisher; and because a responder can still reach the subject through a
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// reply, the ask is signed with the mesh's key and the engine verifies it — the row bounds who is granted the
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// publish, the signature who is believed.
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{State: "a hand-over asked of a machine", Writer: "controller, at its terminal", KeptIn: "the machine, beside its state",
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Others: "the engine verifies the mesh's signature and records it, or refuses",
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Subjects: []string{"mesh.node.*.ask.hand-over"}, Writes: isController},
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// The operator asking a machine's engine for a fresh search for setuid programs, at the controller's
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// terminal (novox/hq issue 361): signed as a hand-over is, under a signing context of its own.
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{State: "a fresh setuid search asked of a machine", Writer: "controller, at its terminal",
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KeptIn: "the machine, which throws its last search away", Others: "the engine verifies the mesh's signature and starts it, or refuses",
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Subjects: []string{"mesh.node.*.ask.setuid-search"}, Writes: isController},
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{State: "a machine's applied state and its report", Writer: "the node-engine's apply queue",
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KeptIn: "the machine; the report on the bus", Others: "the reconcile and a delivery enqueue, never apply",
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// And its health statement between reports (novox/hq ADR 0240): the same writer stating the same
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// machine, inside the grant it already had (`mesh.control.<its own>.>`). And a line mesh-cli was given
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// on the machine (novox/hq ADR 0272): the node is what the controller judges the terminal by, so that
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// subject is this machine's engine's alone.
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Subjects: []string{"mesh.control.*.report", "mesh.control.*.health", "mesh.control.*.cli"}, Writes: ownMachine},
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{State: "the controller lease", Writer: "the controller instance holding it", KeptIn: "key-value " + LeaseBucket,
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Others: "a candidate waits", Subjects: kvOf(LeaseBucket), Writes: isController},
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{State: "plans and their tiers", Writer: "controller (lease holder), compare-and-set on the plan's revision",
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KeptIn: "the controller's store", Others: "read through plans"},
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{State: "conditions", Writer: "controller", KeptIn: "key-value " + ConditionsBucket + " (and its history, " +
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ConditionHistoryBucket + ")", Others: "raise or clear only through observations the controller reads",
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Subjects: append(kvOf(ConditionsBucket), kvOf(ConditionHistoryBucket)...), Writes: isController},
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{State: "calls and their outcomes", Writer: "controller", KeptIn: "key-value " + CallsBucket,
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Others: "read by id", Subjects: kvOf(CallsBucket), Writes: isController},
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{State: "the hand-act log", Writer: "controller, through the verbs that act", KeptIn: "key-value " + HandActsBucket,
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Others: "—", Subjects: kvOf(HandActsBucket), Writes: isController},
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// What the healers did (novox/hq to-be 45 §7, Phase 3): the controller's alone, in its store — the
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// budgets and the mesh-wide brake are counted from it, so a controller restarting cannot reset them.
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{State: "the healers' acts and their brake", Writer: "controller (lease holder), each act begun before it is made",
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KeptIn: "the controller's store", Others: "read through healers; each act said as healer-acted and in its condition's tried"},
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{State: "stream definitions and bus permissions", Writer: "controller", KeptIn: "the bus", Others: "—",
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// A stream's definition, and a durable consumer's by the API that names it so. Not every
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// consumer create: a module watching its own bucket makes and deletes an ordered consumer on the
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// bucket's stream (ADR 0201), which defines nothing the mesh keeps.
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Subjects: []string{"$JS.API.STREAM.CREATE.>", "$JS.API.STREAM.UPDATE.>", "$JS.API.STREAM.DELETE.>",
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"$JS.API.CONSUMER.DURABLE.CREATE.>"},
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Writes: isController},
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{State: "builds and their outcomes", Writer: "the build seat's holder", KeptIn: "its own state",
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Others: "the controller asks",
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Subjects: []string{"mesh.seat.node-build-agent.event.built", "mesh.seat.mesh-build-machine.event.built"},
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Writes: holdsSeatOf,
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Shared: "every machine holding the build seat answers the asks it took; each outcome names its ask"},
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{State: "a merge announced", Writer: "one announcer per forge (the hook, or the poll when the hook is absent — never both)",
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KeptIn: "the bus", Others: "—", Subjects: []string{"mesh.mod.*.event.pull.merged"}, Writes: ownModule},
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// A pull request's head, before it merges (novox/hq to-be 45 §9): the same one announcer.
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{State: "a pull request's head announced", Writer: "the forge's announcer, the one that announces its merges",
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KeptIn: "the bus", Others: "the controller asks the build seat to check it", Subjects: []string{"mesh.mod.*.event.pull.updated"},
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Writes: ownModule},
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{State: "a pull request's merge check", Writer: "the build seat's holder that ran it, said as the controller's `checked`",
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KeptIn: "the bus", Others: "the forge's holder sets it as the pull request's status"},
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{State: "a provider's standing", Writer: "the provider", KeptIn: "the provider's events",
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Others: "the controller keeps the newest word as a condition",
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Subjects: []string{"mesh.mod.*.event.provisioner.failing", "mesh.mod.*.event.provisioner.recovered",
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"mesh.mod.*.event.provisioner.retirement"},
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Writes: ownModule},
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{State: "the operator-channel's open messages", Writer: "the seat's holder", KeptIn: "its own key-value state",
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Others: "—"},
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{State: "the facts snapshot", Writer: "controller", KeptIn: "the artifact store, facts/latest",
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Others: "the build seat reads"},
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// What a consumer gave up on (novox/hq issue 330): copied by the controller from the server's notice,
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// and delivered again or dropped only through its verb, with why.
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{State: "a message a consumer gave up on", Writer: "controller", KeptIn: "the bus, the stream " + DeadLettersStream,
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Others: "read, delivered again or dropped through the controller's dead-letters verb",
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Subjects: []string{deadLetterPrefix + ">", againPrefix + ">"}, Writes: isController},
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}
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// CheckWriters refuses a grant that lets a principal publish on a subject the writers table gives
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// another writer (to-be 45 §1): which state, whose, and the pattern that would make a second writer.
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func CheckWriters(p Principal, publish []string) error {
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var problems []string
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for _, pattern := range publish {
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for _, row := range WritersTable {
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if row.Writes == nil {
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continue
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}
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for _, subject := range row.Subjects {
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if !SubjectsOverlap(pattern, subject) || row.Writes(p, pattern) {
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continue
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}
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problems = append(problems, fmt.Sprintf("%s may publish %s, which writes %s (%s), whose writer is %s",
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p.Username(), pattern, row.State, subject, row.Writer))
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}
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}
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}
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if len(problems) == 0 {
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return nil
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}
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return fmt.Errorf("a second writer would be granted (novox/hq to-be 45 §1, one writer per piece of state):\n %s",
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strings.Join(problems, "\n "))
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}
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// SubjectsOverlap says some subject matches both patterns: `*` is one token, `>` one or more to the end.
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func SubjectsOverlap(a, b string) bool {
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x, y := strings.Split(a, "."), strings.Split(b, ".")
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for i := 0; ; i++ {
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switch {
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case i == len(x) && i == len(y):
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return true
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case i == len(x) || i == len(y):
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return false
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case x[i] == ">" || y[i] == ">":
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return true
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case x[i] == "*" || y[i] == "*" || x[i] == y[i]:
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continue
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default:
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return false
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}
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}
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}
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