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Fixed OverlayFS not copying before write
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@james-pre
james-pre committed Oct 17, 2024
1 parent f396938 commit e1636e0
Showing 1 changed file with 41 additions and 34 deletions.
75 changes: 41 additions & 34 deletions src/backends/overlay.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -75,15 +75,15 @@ export class UnmutexedOverlayFS extends FileSystem {
}

public async sync(path: string, data: Uint8Array, stats: Readonly<Stats>): Promise<void> {
await this.createParentDirectories(path);
await this.copyForWrite(path);
if (!(await this.writable.exists(path))) {
await this.writable.createFile(path, 'w', 0o644);
}
await this.writable.sync(path, data, stats);
}

public syncSync(path: string, data: Uint8Array, stats: Readonly<Stats>): void {
this.createParentDirectoriesSync(path);
this.copyForWriteSync(path);
this.writable.syncSync(path, data, stats);
}

Expand Down Expand Up @@ -126,6 +126,8 @@ export class UnmutexedOverlayFS extends FileSystem {
this.checkPath(oldPath);
this.checkPath(newPath);

await this.copyForWrite(oldPath);

try {
await this.writable.rename(oldPath, newPath);
} catch (e) {
Expand All @@ -140,6 +142,8 @@ export class UnmutexedOverlayFS extends FileSystem {
this.checkPath(oldPath);
this.checkPath(newPath);

this.copyForWriteSync(oldPath);

try {
this.writable.renameSync(oldPath, newPath);
} catch (e) {
Expand All @@ -158,7 +162,7 @@ export class UnmutexedOverlayFS extends FileSystem {
throw ErrnoError.With('ENOENT', path, 'stat');
}
const oldStat = new Stats(await this.readable.stat(path));
// Make the oldStat's mode writable. Preserve the topmost part of the mode, which specifies the type
// Make the oldStat's mode writable.
oldStat.mode |= 0o222;
return oldStat;
}
Expand All @@ -173,7 +177,7 @@ export class UnmutexedOverlayFS extends FileSystem {
throw ErrnoError.With('ENOENT', path, 'stat');
}
const oldStat = new Stats(this.readable.statSync(path));
// Make the oldStat's mode writable. Preserve the topmost part of the mode, which specifies the type.
// Make the oldStat's mode writable.
oldStat.mode |= 0o222;
return oldStat;
}
Expand All @@ -185,7 +189,7 @@ export class UnmutexedOverlayFS extends FileSystem {
}
// Create an OverlayFile.
const file = await this.readable.openFile(path, parseFlag('r'));
const stats = new Stats(await file.stat());
const stats = await file.stat();
const { buffer } = await file.read(new Uint8Array(stats.size));
return new PreloadFile(this, path, flag, stats, buffer);
}
Expand All @@ -196,7 +200,7 @@ export class UnmutexedOverlayFS extends FileSystem {
}
// Create an OverlayFile.
const file = this.readable.openFileSync(path, parseFlag('r'));
const stats = new Stats(file.statSync());
const stats = file.statSync();
const data = new Uint8Array(stats.size);
file.readSync(data);
return new PreloadFile(this, path, flag, stats, data);
Expand All @@ -216,11 +220,13 @@ export class UnmutexedOverlayFS extends FileSystem {

public async link(srcpath: string, dstpath: string): Promise<void> {
this.checkInitialized();
await this.copyForWrite(srcpath);
await this.writable.link(srcpath, dstpath);
}

public linkSync(srcpath: string, dstpath: string): void {
this.checkInitialized();
this.copyForWriteSync(srcpath);
this.writable.linkSync(srcpath, dstpath);
}

Expand Down Expand Up @@ -266,14 +272,14 @@ export class UnmutexedOverlayFS extends FileSystem {
if (await this.writable.exists(path)) {
await this.writable.rmdir(path);
}
if (await this.exists(path)) {
// Check if directory is empty.
if ((await this.readdir(path)).length > 0) {
throw ErrnoError.With('ENOTEMPTY', path, 'rmdir');
} else {
await this.deletePath(path);
}
if (!(await this.exists(path))) {
return;
}
// Check if directory is empty.
if ((await this.readdir(path)).length) {
throw ErrnoError.With('ENOTEMPTY', path, 'rmdir');
}
await this.deletePath(path);
}

public rmdirSync(path: string): void {
Expand All @@ -284,14 +290,14 @@ export class UnmutexedOverlayFS extends FileSystem {
if (this.writable.existsSync(path)) {
this.writable.rmdirSync(path);
}
if (this.existsSync(path)) {
// Check if directory is empty.
if (this.readdirSync(path).length > 0) {
throw ErrnoError.With('ENOTEMPTY', path, 'rmdir');
} else {
void this.deletePath(path);
}
if (!this.existsSync(path)) {
return;
}
// Check if directory is empty.
if (this.readdirSync(path).length) {
throw ErrnoError.With('ENOTEMPTY', path, 'rmdir');
}
void this.deletePath(path);
}

public async mkdir(path: string, mode: number): Promise<void> {
Expand Down Expand Up @@ -463,20 +469,25 @@ export class UnmutexedOverlayFS extends FileSystem {
* - Ensures p is on writable before proceeding. Throws an error if it doesn't exist.
* - Calls f to perform operation on writable.
*/
private operateOnWritable(path: string): void {
private copyForWriteSync(path: string): void {
if (!this.existsSync(path)) {
throw ErrnoError.With('ENOENT', path, 'operateOnWriteable');
throw ErrnoError.With('ENOENT', path, 'copyForWrite');
}
if (!this.writable.existsSync(dirname(path))) {
this.createParentDirectoriesSync(path);
}
if (!this.writable.existsSync(path)) {
// File is on readable storage. Copy to writable storage before
// changing its mode.
this.copyToWritableSync(path);
}
}

private async operateOnWritableAsync(path: string): Promise<void> {
private async copyForWrite(path: string): Promise<void> {
if (!(await this.exists(path))) {
throw ErrnoError.With('ENOENT', path, 'operateOnWritable');
throw ErrnoError.With('ENOENT', path, 'copyForWrite');
}

if (!(await this.writable.exists(dirname(path)))) {
await this.createParentDirectories(path);
}

if (!(await this.writable.exists(path))) {
Expand All @@ -496,12 +507,10 @@ export class UnmutexedOverlayFS extends FileSystem {
}

const data = new Uint8Array(stats.size);
const readable = this.readable.openFileSync(path, parseFlag('r'));
using readable = this.readable.openFileSync(path, parseFlag('r'));
readable.readSync(data);
readable.closeSync();
const writable = this.writable.openFileSync(path, parseFlag('w'));
using writable = this.writable.openFileSync(path, parseFlag('w'));
writable.writeSync(data);
writable.closeSync();
}

private async copyToWritable(path: string): Promise<void> {
Expand All @@ -512,12 +521,10 @@ export class UnmutexedOverlayFS extends FileSystem {
}

const data = new Uint8Array(stats.size);
const readable = await this.readable.openFile(path, parseFlag('r'));
await using readable = await this.readable.openFile(path, parseFlag('r'));
await readable.read(data);
await readable.close();
const writable = await this.writable.openFile(path, parseFlag('w'));
await using writable = await this.writable.openFile(path, parseFlag('w'));
await writable.write(data);
await writable.close();
}
}

Expand Down

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