jochen
76b63744e6
Modules talk over the bus. The power module's bundle puts each fresh reading of its own sampler in its state draw, keyed by the machine; the bar's block shows that state, which the bar's bundle watches under the read the mesh grants it. A new catalogue check refuses a module naming another module's path under /run or /var/lib.
119 lines
3.9 KiB
Go
119 lines
3.9 KiB
Go
package main
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import (
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"encoding/json"
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"fmt"
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"os"
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"path/filepath"
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"regexp"
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"sort"
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"strconv"
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"time"
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stdio "git.novox.be/novox/mesh-sdk/go"
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)
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// The values other modules keep on the bus for a block they contributed (novox/hq ADR 0260).
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//
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// A block that `shows` a state is rendered as a custom block running `i3status-value <state> <key>`.
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// i3status-rs cannot reach the bus, and this bundle can: the node's runtime launched it, and the mesh
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// granted this module a read of every state the modules on its machine offer the bar. So it watches each
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// state its bars name and leaves the value's text in this module's own directory, where the block's
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// command reads it. No file of another module is read, and nothing but the bus passes between them.
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// valueCall is how a bar names a value: the command the template renders.
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var valueCall = regexp.MustCompile(`i3status-value ([a-z0-9][a-z0-9-]*\.[a-z0-9][a-z0-9-]*) ([^\s"]+)`)
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// Wanted is one state and key a bar shows.
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type Wanted struct{ State, Key string }
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func (w Wanted) file() string { return w.State + "@" + w.Key }
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// wantedIn is every value the bars' files name, each once, in order.
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func wantedIn(files []string) []Wanted {
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seen := map[Wanted]bool{}
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for _, f := range files {
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raw, err := os.ReadFile(f)
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if err != nil {
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continue
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}
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for _, m := range valueCall.FindAllStringSubmatch(string(raw), -1) {
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seen[Wanted{State: m[1], Key: m[2]}] = true
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}
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}
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out := make([]Wanted, 0, len(seen))
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for w := range seen {
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out = append(out, w)
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}
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sort.Slice(out, func(i, j int) bool { return out[i].file() < out[j].file() })
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return out
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}
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// valuesDir is where the values are left: the account's runtime directory, gone at logout.
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func valuesDir() string {
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return filepath.Join(runUserDir, strconv.Itoa(os.Getuid()), "i3status-rust", "values")
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}
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// keep writes one change of a value to its file: the value's `text`, or no file once it is deleted.
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func keep(dir string, w Wanted, c stdio.StateChange) error {
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path := filepath.Join(dir, w.file())
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if c.Op == "delete" || c.Op == "purge" {
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if err := os.Remove(path); err != nil && !os.IsNotExist(err) {
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return err
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}
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return nil
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}
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var v struct {
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Text string `json:"text"`
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}
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if err := json.Unmarshal(c.Value, &v); err != nil {
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return fmt.Errorf("%s's value for %s has no text: %w", w.State, w.Key, err)
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}
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if err := os.MkdirAll(dir, 0o700); err != nil {
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return err
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}
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tmp := path + ".new"
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if err := os.WriteFile(tmp, []byte(v.Text+"\n"), 0o600); err != nil {
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return err
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}
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return os.Rename(tmp, path)
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}
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// Watcher is a function that watches one key of one state; the SDK's in the bundle, a fake in a test.
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type Watcher func(state, key string, handle func(stdio.StateChange) error) error
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// followValues watches every value the bars name, starting the ones not yet watched each time it is
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// called; one the runtime refuses — a read not granted yet — is tried again the next time.
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func followValues(files []string, dir string, watching map[Wanted]bool, watch Watcher) []string {
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var said []string
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for _, w := range wantedIn(files) {
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if watching[w] {
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continue
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}
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w := w
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err := watch(w.State, w.Key, func(c stdio.StateChange) error { return keep(dir, w, c) })
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if err != nil {
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said = append(said, fmt.Sprintf("cannot watch %s %s: %v", w.State, w.Key, err))
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continue
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}
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watching[w] = true
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}
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return said
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}
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// FollowValues runs followValues every half minute for as long as the bundle runs, so a block a push
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// adds is followed without a restart.
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func FollowValues() {
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watching := map[Wanted]bool{}
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watch := func(state, key string, handle func(stdio.StateChange) error) error {
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return stdio.State(state).Watch(key, handle)
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}
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for {
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files, _ := filepath.Glob(filepath.Join(configDir(), "*.toml"))
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for _, s := range followValues(files, valuesDir(), watching, watch) {
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fmt.Fprintln(os.Stderr, "i3status-rust:", s)
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}
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time.Sleep(30 * time.Second)
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}
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}
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