Nanoc 4.9.2+ crashes when creating hard links on Chrome OS, running inside Termux.

[printfn]

Nanoc 4.9.2+ crashes when creating hard links on Chrome OS, running inside Termux.

Steps to reproduce

rm -rf docs # I've renamed the output directory to 'docs'
nanoc

Expected behavior

Building the nanoc site

Actual behavior

Crash log:
https://gist.github.com/printfn/6791787b4fb0bb68c86c08b94031a6ea

Details

The issue seems to be caused by the use of hard links in nanoc 4.9.2. I can reproduce it on 4.9.2, and on the latest 4.11.0. The issue does NOT occur on 4.9.1.

I'm using an Acer Chromebook 15 (CB5-571), running nanoc through Termux from the Play Store. The environment is sandboxed, and the developer mode is disabled.

[denisdefreyne]

Hey,

I investigated this but unfortunately couldn’t find directly what is causing this. I don’t have a Chromebook device to test this out, unfortunately.

Can you do something for me, that would shed more light on the situation?

1. Set a breakpoint in lib/nanoc/base/services/item_rep_writer.rb:53, or perhaps add sleep 120 right in front of that line to emulate a breakpoint.

2. Right before the breakpoint (or the sleep call), add puts ">>> temp_path = #{temp_path}".

3. Run the modified Nanoc again. You’ll see something like this in the output:

   >>> temp_path = /data/data/com.termux/files/usr/tmp/nanoc20190206-4245-mvsz4o/text_items/4
   

4. Let me know whether the base directory (printed above) exists. Following the example above, /data/data/com.termux/files/usr/tmp/nanoc20190206-4245-mvsz4o/text_items should exist, as well as its parent directory.

5. Let me know what the permissions are of the base directory (…/text_items).

6. Let me know whether you can manually create a file in the directory (e.g. touch …/text_items/12345, replacing … with the base directory).

Hopefully, that will give me enough information to debug this further.

[printfn]

I tried your suggestions, with these results:

The text_items directory exists, and the files 0 to 4 also exist. These are the permissions:

$ ls -al ../../usr/tmp/nanoc20190209-2226-13g4tvj/text_items/
total 76
drwx------    2 u0_a55   u0_a55        4096 Feb  9 11:53 .
drwx------    3 u0_a55   u0_a55        4096 Feb  9 11:52 ..
-rw-------    1 u0_a55   u0_a55        6243 Feb  9 11:52 0
-rw-------    1 u0_a55   u0_a55        4472 Feb  9 11:52 1
-rw-------    1 u0_a55   u0_a55        3647 Feb  9 11:52 2
-rw-------    1 u0_a55   u0_a55        9165 Feb  9 11:52 3
-rw-------    1 u0_a55   u0_a55        4882 Feb  9 11:52 4

Manually creating a file in this directory also works, and it has default permissions of -rw-------.

[printfn]

I also tried running:

ln ../../usr/tmp/nanoc20190209-2226-13g4tvj/text_items/4 test

This fails with ln: test: Permission denied.

On the other hand, running

ln -s ../../usr/tmp/nanoc20190209-2226-13g4tvj/text_items/4 test

succeeds, and vim test afterwards lets me edit the file.

[denisdefreyne]

Can you replace

          begin
            FileUtils.ln(temp_path, raw_path, force: true)
          rescue Errno::EXDEV
            FileUtils.cp(temp_path, raw_path)
          end

in item_rep_writer.rb, lines 62 to 66, with

          FileUtils.cp(temp_path, raw_path)

and let me know whether that works?

[printfn]

Yes, that causes it to work.

[denisdefreyne]

OK, I think #1406 has a workaround — it falls back to not using hardlinking, which is suboptimal, but at least the desires behavior (having the right files in the right places) is there.

[printfn]

Your patch uses EACCESS, but it should be EACCES. I've applied it now, and it fixes the bug.

[denisdefreyne]

Whoops, I thought that was a typo on my part. Fixed.

[denisdefreyne]

I found something relevant:

facebook/create-react-app#1832 (comment)

Due to Android's SELinux policies, you cannot hard link as non-root

So I suppose that copying (rather than hardlinking) is the proper fix.

[denisdefreyne]

I will merge and release Nanoc once CI has passed.

[denisdefreyne]

Nanoc 4.11.1 is now released. Can you double-check to verify that this release works for you?