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fix(publication): complete concurrent rotation handoff #51

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Merged
rynfar merged 1 commit into from
Sep 3, 2026
+1,296 −33
Merged

fix(publication): complete concurrent rotation handoff #51

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126 changes: 112 additions & 14 deletions scripts/lib/pylon-bounded-file.mjs
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,33 @@ export class BoundedFileUnlinkedDuringReadError extends Error {
}
}

function statEvidence(stat) {
return Object.freeze({
dev: stat.dev,
ino: stat.ino,
size: stat.size,
mtimeMs: stat.mtimeMs,
ctimeMs: stat.ctimeMs,
nlink: stat.nlink,
});
}

export class BoundedFileLinkRetiredBeforeReadError extends Error {
constructor(path, description, bytes, expectedSha256, pathEntry, openedHandle) {
super(`${description} changed while it was read because one publication hardlink was retired before the file was opened.`);
this.name = "BoundedFileLinkRetiredBeforeReadError";
this.path = path;
this.description = description;
this.bytes = Buffer.from(bytes);
this.expectedSha256 = expectedSha256;
this.sha256 = createHash("sha256").update(this.bytes).digest("hex");
this.statTransition = Object.freeze({
pathEntry: statEvidence(pathEntry),
openedHandle: statEvidence(openedHandle),
});
}
}

function sameInodeReadBounds(left, right) {
return left.dev === right.dev && left.ino === right.ino && left.size === right.size &&
left.mtimeMs === right.mtimeMs;
Expand All @@ -37,6 +64,25 @@ function isPinnedHandleRemoval(pathEntry, before, after, extraBytes, finalPathMi
sameInodeReadBounds(before, after) && before.nlink > 0 && after.nlink === 0;
}

function initialRetirementKind(pathEntry, openedHandle, expectedSha256) {
if (
expectedSha256 === null || !sameInodeReadBounds(pathEntry, openedHandle) ||
pathEntry.ctimeMs === openedHandle.ctimeMs
) return null;
if (pathEntry.nlink === 2 && openedHandle.nlink === 1) return "link-retired";
if (pathEntry.nlink === 1 && openedHandle.nlink === 0) return "unlinked";
return null;
}

function isStableLinkRetirementBeforeRead(before, after, extraBytes, finalPathEntry, finalPathMissing) {
return !finalPathMissing && extraBytes === 0 && !finalPathEntry.isSymbolicLink?.() && finalPathEntry.isFile() &&
sameStat(before, after) && sameStat(after, finalPathEntry);
}

function isStableHandleRemovalBeforeRead(before, after, extraBytes, finalPathMissing) {
return finalPathMissing && extraBytes === 0 && sameStat(before, after);
}

function exactSha256(bytes, expectedSha256) {
return expectedSha256 !== null && createHash("sha256").update(bytes).digest("hex") === expectedSha256;
}
Expand Down Expand Up @@ -84,7 +130,11 @@ export async function readBoundedRegularFile(
let before = await handle.stat();
if (!before.isFile()) throw new Error(`${description} is not one regular non-symlink file.`);
if (validateHandle) before = await validateHandle(handle, before, description);
if (!sameStat(pathEntry, before)) throw new Error(`${description} changed while it was read.`);
let retirementBeforeRead = null;
if (!sameStat(pathEntry, before)) {
retirementBeforeRead = initialRetirementKind(pathEntry, before, expectedSha256);
if (retirementBeforeRead === null) throw new Error(`${description} changed while it was read.`);
}
if (before.size < minBytes || before.size > maxBytes) throw new Error(`${description} exceeds its format byte limit or is malformed.`);
await hooks?.afterInitialStat?.({ path, handle, stat: before });
const bytes = Buffer.alloc(before.size);
Expand All @@ -106,14 +156,36 @@ export async function readBoundedRegularFile(
if (error?.code !== "ENOENT") throw error;
finalPathMissing = true;
}
if (
isPinnedHandleRemoval(pathEntry, before, after, extraBytes, finalPathMissing) &&
exactSha256(bytes, expectedSha256)
) {
throw new BoundedFileUnlinkedDuringReadError(path, description, bytes, expectedSha256);
if (exactSha256(bytes, expectedSha256)) {
if (
retirementBeforeRead === "link-retired" &&
isStableLinkRetirementBeforeRead(before, after, extraBytes, finalPathEntry, finalPathMissing)
) {
throw new BoundedFileLinkRetiredBeforeReadError(
path,
description,
bytes,
expectedSha256,
pathEntry,
before,
);
}
if (
retirementBeforeRead === "unlinked" &&
isStableHandleRemovalBeforeRead(before, after, extraBytes, finalPathMissing)
) {
throw new BoundedFileUnlinkedDuringReadError(path, description, bytes, expectedSha256);
}
if (
retirementBeforeRead === null &&
isPinnedHandleRemoval(pathEntry, before, after, extraBytes, finalPathMissing)
) {
throw new BoundedFileUnlinkedDuringReadError(path, description, bytes, expectedSha256);
}
}
if (
extraBytes !== 0 || finalPathMissing || finalPathEntry.isSymbolicLink?.() || !finalPathEntry.isFile() ||
retirementBeforeRead !== null || extraBytes !== 0 || finalPathMissing ||
finalPathEntry.isSymbolicLink?.() || !finalPathEntry.isFile() ||
!sameStat(before, after) || !sameStat(after, finalPathEntry)
) throw new Error(`${description} changed while it was read.`);
return bytes;
Expand Down Expand Up @@ -165,7 +237,11 @@ export function readBoundedRegularFileSync(
try {
const before = statFile(descriptor);
if (!before.isFile()) throw new Error(`${description} is not one regular non-symlink file.`);
if (!sameStat(pathEntry, before)) throw new Error(`${description} changed while it was read.`);
let retirementBeforeRead = null;
if (!sameStat(pathEntry, before)) {
retirementBeforeRead = initialRetirementKind(pathEntry, before, expectedSha256);
if (retirementBeforeRead === null) throw new Error(`${description} changed while it was read.`);
}
if (before.size < minBytes || before.size > maxBytes) throw new Error(`${description} exceeds its format byte limit or is malformed.`);
hooks?.afterInitialStat?.({ path, descriptor, stat: before });
const bytes = Buffer.alloc(before.size);
Expand All @@ -187,14 +263,36 @@ export function readBoundedRegularFileSync(
if (error?.code !== "ENOENT") throw error;
finalPathMissing = true;
}
if (
isPinnedHandleRemoval(pathEntry, before, after, extraBytes, finalPathMissing) &&
exactSha256(bytes, expectedSha256)
) {
throw new BoundedFileUnlinkedDuringReadError(path, description, bytes, expectedSha256);
if (exactSha256(bytes, expectedSha256)) {
if (
retirementBeforeRead === "link-retired" &&
isStableLinkRetirementBeforeRead(before, after, extraBytes, finalPathEntry, finalPathMissing)
) {
throw new BoundedFileLinkRetiredBeforeReadError(
path,
description,
bytes,
expectedSha256,
pathEntry,
before,
);
}
if (
retirementBeforeRead === "unlinked" &&
isStableHandleRemovalBeforeRead(before, after, extraBytes, finalPathMissing)
) {
throw new BoundedFileUnlinkedDuringReadError(path, description, bytes, expectedSha256);
}
if (
retirementBeforeRead === null &&
isPinnedHandleRemoval(pathEntry, before, after, extraBytes, finalPathMissing)
) {
throw new BoundedFileUnlinkedDuringReadError(path, description, bytes, expectedSha256);
}
}
if (
extraBytes !== 0 || finalPathMissing || finalPathEntry.isSymbolicLink?.() || !finalPathEntry.isFile() ||
retirementBeforeRead !== null || extraBytes !== 0 || finalPathMissing ||
finalPathEntry.isSymbolicLink?.() || !finalPathEntry.isFile() ||
!sameStat(before, after) || !sameStat(after, finalPathEntry)
) throw new Error(`${description} changed while it was read.`);
return bytes;
Expand Down
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