fix(fslib): handle float timestamps in convertToBigIntStats (#6988)

## Summary
Fixes RangeError when converting floating-point timestamps to BigInt in
the `convertToBigIntStats` function.

## Problem
The `convertToBigIntStats()` function fails when file stats contain
non-integer timestamps (e.g., `1763746784088.47`), throwing:
```
RangeError: The number 1763746784088.47 cannot be converted to a BigInt because it is not an integer
```

This occurs when ZIP file entries have timestamps with floating-point
precision, particularly observed in Yarn 6.0.0-rc.5 when building with
Storybook.

## Solution
Use `Math.floor()` to ensure integer values before BigInt conversion on
line 194 of `packages/yarnpkg-fslib/sources/statUtils.ts`.

## Changes
- Changed `BigInt(element)` to `BigInt(Math.floor(element))`

## Testing
- Tested with Yarn 6.0.0-rc.5 + Storybook build
- Verified the RangeError no longer occurs with floating-point
timestamps

## Related
This issue was discovered while running `yarn storybook build` with Yarn
6.0.0-rc.5.

---------

Co-authored-by: Maël Nison <[email protected]>

Author: nelsondude

.pnp.cjs

@@ -0,0 +1,38 @@
+releases:
+  "@yarnpkg/fslib": patch
+
+declined:
+  - "@yarnpkg/plugin-catalog"
+  - "@yarnpkg/plugin-compat"
+  - "@yarnpkg/plugin-constraints"
+  - "@yarnpkg/plugin-dlx"
+  - "@yarnpkg/plugin-essentials"
+  - "@yarnpkg/plugin-exec"
+  - "@yarnpkg/plugin-file"
+  - "@yarnpkg/plugin-git"
+  - "@yarnpkg/plugin-github"
+  - "@yarnpkg/plugin-init"
+  - "@yarnpkg/plugin-jsr"
+  - "@yarnpkg/plugin-link"
+  - "@yarnpkg/plugin-nm"
+  - "@yarnpkg/plugin-npm"
+  - "@yarnpkg/plugin-npm-cli"
+  - "@yarnpkg/plugin-pack"
+  - "@yarnpkg/plugin-patch"
+  - "@yarnpkg/plugin-pnp"
+  - "@yarnpkg/plugin-pnpm"
+  - "@yarnpkg/plugin-stage"
+  - "@yarnpkg/plugin-typescript"
+  - "@yarnpkg/plugin-version"
+  - "@yarnpkg/plugin-workspace-tools"
+  - vscode-zipfs
+  - "@yarnpkg/builder"
+  - "@yarnpkg/cli"
+  - "@yarnpkg/core"
+  - "@yarnpkg/doctor"
+  - "@yarnpkg/libzip"
+  - "@yarnpkg/nm"
+  - "@yarnpkg/pnp"
+  - "@yarnpkg/pnpify"
+  - "@yarnpkg/sdks"
+  - "@yarnpkg/shell"

.yarn/versions/78344001.yml

@@ -191,18 +191,18 @@ export function convertToBigIntStats(stats: Stats): BigIntStats {
       const element = stats[key as keyof typeof stats];
       if (typeof element === `number`) {
         // @ts-expect-error Typescript isn't able to tell this is valid
-        bigintStats[key as keyof typeof bigintStats] = BigInt(element);
+        bigintStats[key as keyof typeof bigintStats] = BigInt(Math.floor(element));
       } else if (nodeUtils.types.isDate(element)) {
         // @ts-expect-error Typescript isn't able to tell this is valid
         bigintStats[key as keyof typeof bigintStats] = new Date(element);
       }
     }
   }
 
-  bigintStats.atimeNs = bigintStats.atimeMs * BigInt(1e6);
-  bigintStats.mtimeNs = bigintStats.mtimeMs * BigInt(1e6);
-  bigintStats.ctimeNs = bigintStats.ctimeMs * BigInt(1e6);
-  bigintStats.birthtimeNs = bigintStats.birthtimeMs * BigInt(1e6);
+  bigintStats.atimeNs = bigintStats.atimeMs * BigInt(1e6) + BigInt(Math.floor((stats.atimeMs % 1) * 1e3)) * BigInt(1e3);
+  bigintStats.mtimeNs = bigintStats.mtimeMs * BigInt(1e6) + BigInt(Math.floor((stats.mtimeMs % 1) * 1e3)) * BigInt(1e3);
+  bigintStats.ctimeNs = bigintStats.ctimeMs * BigInt(1e6) + BigInt(Math.floor((stats.ctimeMs % 1) * 1e3)) * BigInt(1e3);
+  bigintStats.birthtimeNs = bigintStats.birthtimeMs * BigInt(1e6) + BigInt(Math.floor((stats.birthtimeMs % 1) * 1e3)) * BigInt(1e3);
 
   return bigintStats as unknown as BigIntStats;
 }

packages/yarnpkg-fslib/sources/statUtils.ts

@@ -17,11 +17,16 @@ export const ZIP_DIR4 = ppath.join(
   npath.toPortablePath(__dirname),
   `fixtures/symlink.zip` as Filename,
 );
+export const ZIP_DIR5 = ppath.join(
+  npath.toPortablePath(__dirname),
+  `fixtures/implicit-folders.zip` as Filename,
+);
 
 export const ZIP_FILE1 = ppath.join(ZIP_DIR1, `foo.txt`);
 export const ZIP_FILE2 = ppath.join(ZIP_DIR2, `foo.txt`);
 export const ZIP_FILE3 = ppath.join(ZIP_DIR3, `foo.txt`);
 export const ZIP_FILE4 = ppath.join(ZIP_DIR4, `foo.txt`);
+export const ZIP_FILE5 = ppath.join(ZIP_DIR5, `foo.txt`);
 
 afterEach(() => {
   jest.useRealTimers();
@@ -86,6 +91,15 @@ describe(`ZipOpenFS`, () => {
     fs.discardAndClose();
   });
 
+  it(`can read stats from a zip file with implicit folders`, () => {
+    const fs = new ZipOpenFS();
+
+    expect(fs.statSync(ppath.join(ZIP_DIR5, `node_modules`)).isDirectory()).toBe(true);
+    expect(fs.statSync(ppath.join(ZIP_DIR5, `node_modules`), {bigint: true}).isDirectory()).toBe(true);
+
+    fs.discardAndClose();
+  });
+
   it(`can read from a zip file that's a symlink`, () => {
     const fs = new ZipOpenFS();