| 1 | import type { File } from "expo-file-system"; |
| 2 | |
| 3 | let tempFileSequence = 0; |
| 4 | |
| 5 | /** |
| 6 | * Replaces a file's contents through a sibling temp file and an overwriting |
| 7 | * rename, so an interrupted write (app restart, process death) never leaves a |
| 8 | * truncated document at the final path. Each write stages through its own |
| 9 | * temp file so concurrent writers to the same destination cannot move or |
| 10 | * clobber each other's staging file mid-flight. |
| 11 | */ |
| 12 | export async function writeFileAtomically(file: File, contents: string): Promise<void> { |
| 13 | const { File: FileConstructor } = await import("expo-file-system"); |
| 14 | tempFileSequence += 1; |
| 15 | const temp = new FileConstructor(file.parentDirectory, `${file.name}.${tempFileSequence}.tmp`); |
| 16 | temp.create({ intermediates: true, overwrite: true }); |
| 17 | await temp.write(contents); |
| 18 | temp.moveSync(file, { overwrite: true }); |
| 19 | } |