No such file or directory for symlinks whose targets don't exist

[vjpr]

If a symlink points to a file that doesn't exist, it should not break the diff.

It looks like symlinks are not handled well in general.

[gliviu]

It looks like symlinks are not handled well in general.

Aside 'symlink does not exist' is it any other issue that you saw? Please be speciffic. There has been a lot of effort added to properly support symlinks in this project.

If a symlink points to a file that doesn't exist, it should not break the diff.

This was a design decision. If you know you have broken symlinks you can always use --skip-symlinks option.
What you probably want is a 'ignore broken symlinks' option which was not implemented because it was never requested.

[szpak]

Recently I have encounter the same issue with a broken symlink (1.8.0):

$ dircompare.js -c -lrd /home/foobar/Documents/ /mnt/foo/home/foobar/Documents/
Error occurred: Error: ENOENT: no such file or directory, stat '/home/foobar/Documents/broken-symlink'
    at Object.statSync (fs.js:855:3)
    at /home/foobar/binary/dir-compare/node_modules/dir-compare/compareSync.js:28:35
    at Array.forEach (<anonymous>)
    at getEntries (/home/foobar/binary/dir-compare/node_modules/dir-compare/compareSync.js:19:20)
    at compare (/home/foobar/binary/dir-compare/node_modules/dir-compare/compareSync.js:83:37)
    at compare (/home/foobar/binary/dir-compare/node_modules/dir-compare/compareSync.js:141:17)
    at Object.compareSync (/home/foobar/binary/dir-compare/node_modules/dir-compare/index.js:39:5)
    at /home/foobar/binary/dir-compare/node_modules/dir-compare/dircompare.js:113:38
    at Promise._execute (/home/foobar/binary/dir-compare/node_modules/bluebird/js/release/debuggability.js:272:9)
    at Promise._resolveFromExecutor (/home/foobar/binary/dir-compare/node_modules/bluebird/js/release/promise.js:475:18)
    at new Promise (/home/foobar/binary/dir-compare/node_modules/bluebird/js/release/promise.js:77:14)
    at run (/home/foobar/binary/dir-compare/node_modules/dir-compare/dircompare.js:112:35)
    at Object.<anonymous> (/home/foobar/binary/dir-compare/node_modules/dir-compare/dircompare.js:144:1)
    at Module._compile (internal/modules/cjs/loader.js:778:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)
    at Module.load (internal/modules/cjs/loader.js:653:32)

It helped me to find some broken symlinks ;-), however, in some corner cases I had to exclude proper paths (or ignore symlinks at all), e.g.:

$ ll /home/foobar/.mozilla/firefox/some-profile/lock
lrwxrwxrwx. 1 foobar foobar 19 Dec 17 00:30 /home/foobar/.mozilla/firefox/some-profile/lock -> 192.168.1.10:+15293

In a situation the implementation is not overly complicated it would be useful to have an option to ignore broken symlinks assuming they are broken on the both side.

[gliviu]

I think this issue will be resolved if we implement #19.
If dircompare is used with default comparison options (ie. dircompare a b) it will crash as above.
If it uses new 'symlink aware' options (ie. `dircompare --compare-symlinks a b') it will include symlink differences in the report (including broken symlinks).

What do you think?

[szpak]

I'm not sure if crash is the best behavior for broken symlinks. It happens occasionally to break a link (to make it unresolvable) and then it is required to disable all links processing in the comparison . Maybe it could report it as "missing" if a broken link on one side, but is resolvable on the other?

[gliviu]

Agreed, better to avoid crash by default.
I like the idea of reporting 'missing'. Still we can treat it as a special type of entry.

# broken symlink on the left, regular file on the right
[/] a1.txt->missing(broken symlink)
[/] missing->a1.txt(file)
Entries are different
total: 2, equal: 0, distinct: 0, only left: 1, only right: 1

# broken symlink on both sides
[/] a1.txt->missing(broken symlink)
[/] missing->a1.txt(broken symlink)
Entries are different
total: 2, equal: 1, distinct: 0, only left: 0, only right: 0

[szpak]

[/] a1.txt->missing(broken symlink)
[/] a1.txt->missing(broken symlink)
[/] missing->a1.txt(broken symlink)

It sounds good!