atomically
Version:
Read and write files atomically and reliably.
103 lines (55 loc) • 2.78 kB
text/typescript
/* IMPORT */
import path from 'node:path';
import fs from 'stubborn-fs';
import whenExit from 'when-exit';
import {LIMIT_BASENAME_LENGTH} from '../constants';
import type {Disposer} from '../types';
/* MAIN */
//TODO: Maybe publish this as a standalone package
const Temp = {
/* VARIABLES */
store: <Record<string, boolean>> {}, // filePath => purge
/* API */
create: ( filePath: string ): string => {
const randomness = `000000${Math.floor ( Math.random () * 16777215 ).toString ( 16 )}`.slice ( -6 ); // 6 random-enough hex characters
const timestamp = Date.now ().toString ().slice ( -10 ); // 10 precise timestamp digits
const prefix = 'tmp-';
const suffix = `.${prefix}${timestamp}${randomness}`;
const tempPath = `${filePath}${suffix}`;
return tempPath;
},
get: ( filePath: string, creator: ( filePath: string ) => string, purge: boolean = true ): [string, Disposer] => {
const tempPath = Temp.truncate ( creator ( filePath ) );
if ( tempPath in Temp.store ) return Temp.get ( filePath, creator, purge ); // Collision found, try again
Temp.store[tempPath] = purge;
const disposer = () => delete Temp.store[tempPath];
return [tempPath, disposer];
},
purge: ( filePath: string ): void => {
if ( !Temp.store[filePath] ) return;
delete Temp.store[filePath];
fs.attempt.unlink ( filePath );
},
purgeSync: ( filePath: string ): void => {
if ( !Temp.store[filePath] ) return;
delete Temp.store[filePath];
fs.attempt.unlinkSync ( filePath );
},
purgeSyncAll: (): void => {
for ( const filePath in Temp.store ) {
Temp.purgeSync ( filePath );
}
},
truncate: ( filePath: string ): string => { // Truncating paths to avoid getting an "ENAMETOOLONG" error //FIXME: This doesn't really always work, the actual filesystem limits must be detected for this to be implemented correctly
const basename = path.basename ( filePath );
if ( basename.length <= LIMIT_BASENAME_LENGTH ) return filePath; //FIXME: Rough and quick attempt at detecting ok lengths
const truncable = /^(\.?)(.*?)((?:\.[^.]+)?(?:\.tmp-\d{10}[a-f0-9]{6})?)$/.exec ( basename );
if ( !truncable ) return filePath; //FIXME: No truncable part detected, can't really do much without also changing the parent path, which is unsafe, hoping for the best here
const truncationLength = basename.length - LIMIT_BASENAME_LENGTH;
return `${filePath.slice ( 0, - basename.length )}${truncable[1]}${truncable[2].slice ( 0, - truncationLength )}${truncable[3]}`; //FIXME: The truncable part might be shorter than needed here
}
};
/* INIT */
whenExit ( Temp.purgeSyncAll ); // Ensuring purgeable temp files are purged on exit
/* EXPORT */
export default Temp;