error: Uncaught (in promise) AlreadyExists: File exists (os error 17): symlink

[magnusviri]

sudo /usr/local/bin/pkgm install pipenv
error: Uncaught (in promise) AlreadyExists: File exists (os error 17): symlink 'python' -> '/usr/local/pkgs/pipenv.pypa.io/v3000.0.0/venv/bin/python3'
  Deno.symlinkSync(src, dst);
       ^
    at Object.symlinkSync (ext:deno_fs/30_fs.js:519:3)
    at symlink_with_overwrite (file:///Users/james/.pkgx/pkgx.sh/pkgm/v0.11.1/bin/pkgm:501:8)
    at processEntry (file:///Users/james/.pkgx/pkgx.sh/pkgm/v0.11.1/bin/pkgm:375:7)
    at async processEntry (file:///Users/james/.pkgx/pkgx.sh/pkgm/v0.11.1/bin/pkgm:363:9)
    at async processEntry (file:///Users/james/.pkgx/pkgx.sh/pkgm/v0.11.1/bin/pkgm:363:9)
    at async processEntry (file:///Users/james/.pkgx/pkgx.sh/pkgm/v0.11.1/bin/pkgm:363:9)
    at async mirror_directory (file:///Users/james/.pkgx/pkgx.sh/pkgm/v0.11.1/bin/pkgm:350:3)
    at async install (file:///Users/james/.pkgx/pkgx.sh/pkgm/v0.11.1/bin/pkgm:153:5)
    at async file:///Users/james/.pkgx/pkgx.sh/pkgm/v0.11.1/bin/pkgm:65:20

I get this a lot. I have to fix it by just rm -r'ing whatever it says already exists.

[jhheider]

here's the relevant lines:

pkgm/pkgm.ts

Lines 497 to 502 in e3934de

	function symlink_with_overwrite(src: string, dst: string) {
	if (existsSync(dst) && Deno.lstatSync(dst).isSymlink) {
	Deno.removeSync(dst);
	}
	Deno.symlinkSync(src, dst);
	}

notably, the trap checks that the thing it's removing is a symlink before removing it. soooooo... that suggests there's something other than a symlink there. next time you see this, can you ls -l $whatever and check? that trap should probably exit gracefully with a better error message if it finds something other than a symlink.

notably, this will fail with a hard link (i.e. "a file"). so we might be hitting that if it's hardlinking to deal with a boundary issue. as it can do on line 371:

pkgm/pkgm.ts

Lines 352 to 380 in e3934de

	async function processEntry(sourcePath: string, targetPath: string) {
	const fileInfo = await Deno.lstat(sourcePath);
	if (fileInfo.isDirectory) {
	// Create the target directory
	await ensureDir(targetPath);
	// Recursively process the contents of the directory
	for await (const entry of Deno.readDir(sourcePath)) {
	const entrySourcePath = join(sourcePath, entry.name);
	const entryTargetPath = join(targetPath, entry.name);
	await processEntry(entrySourcePath, entryTargetPath);
	}
	} else if (fileInfo.isFile) {
	// Remove the target file if it exists
	if (existsSync(targetPath)) {
	await Deno.remove(targetPath);
	}
	// Create a hard link for files
	await Deno.link(sourcePath, targetPath);
	} else if (fileInfo.isSymlink) {
	// Recreate symlink in the target directory
	const linkTarget = await Deno.readLink(sourcePath);
	symlink_with_overwrite(linkTarget, targetPath);
	} else {
	throw new Error(`unsupported file type at: ${sourcePath}`);
	}
	}
	}

[magnusviri]

I figured this out. existsSync(dst) is returning false when Deno.lstatSync(dst).isSymlink returns true, and it looks like it's because dst is a link to a file that doesn't exist. So existsSync(dst) must be following the link and checking that file if it exists.

[jhheider]

Fascinating and brutal. So, perhaps either the existsSync() is purely redundant, or perhaps we should just switch the ||. || means it'll remove hard links (which is good), but also means it will remove files we didn't install (which is bad).

[magnusviri]

I didn't see your comment until just now. The pull request is what ChatGPT said to do.

[magnusviri]

Sigh, I'm still getting this error. I'll debug it some more next time I work on this.

[jhheider]

The answer is probably:

If deno lstat issymlink then remove
After that, if exists then we need to do something. Probably error unless we have a --force flag, is my guess. Since it'll remove any file. Not the biggest problem in /usr/local, but potentially lossy. Could delete something someone wanted.

[jhheider]

@magnusviri see if #79 fixes it for you. this tries to take a more considered approach:

• if it's a symlink, confidently remove it
• if it still exists afterward, remove it iff -f/--force was passed
• otherwise, complain with a (hopefully) helpful error message

[magnusviri]

It fixed one instance of the problem. I'll keep testing it and let you know if it causes me problems.

[jhheider]

result! i'm hopeful. i didn't want it to smash stuff you wanted, but you should have some recourse to move forward.