--stdin-filename with path separator gives cryptic error message

[cdhowie]

Output of restic version

restic 0.9.3 compiled with go1.11.1 on linux/amd64

How did you run restic exactly?

RESTIC_REPOSITORY set to S3 bucket+prefix, and RESTIC_PASSWORD set appropriately.

# sudo -iu postgres pg_dumpall | restic backup -q --stdin --stdin-filename /root/postgresql-dump.sql
Fatal: unable to save snapshot: Lstat: file does not exist

What backend/server/service did you use to store the repository?

S3

Expected behavior

The backup should complete successfully, or at least a useful error message should be provided. I would not expect Restic to need to stat anything as part of this operation; the repository is in S3 and the file data is provided on standard input.

Actual behavior

Restic gives a "file does not exist" error message.

Steps to reproduce the behavior

Attempt to upload a file with --stdin-filename containing a path separator.

Do you have any idea what may have caused this?

It appears that Restic joins the provided filename to the current working directory Restic is run from; when I omit /root/ then the file is stored in the repository as /root/postgresql-dump.sql (cwd for the command is /root).

Do you have an idea how to solve the issue?

I would suspect this needs a patch to be fixed. A workaround is to cd before running Restic so that it's running from the directory where you want the backed-up file to appear to be stored.

Did restic help you or made you happy in any way?

Yes, this has become my go-to backup tool for all of my machines. My company is using it in production to backup multiple critical servers for quick recovery, while also providing inexpensive and easily-updated offsite backups.

[cdhowie]

As a follow up, I believe the stat errors are coming from restic trying to build the tree objects. I don't know for certain, but I suspect that with --stdin-filename /root/postgresql-dump.sql and a cwd of /root that restic is building the full path /root/root/postgresql-dump.sql. Then, when it tries to build the tree object for /root/root, it can't find that directory and chokes.

So I think the fix here is just to make restic able to handle absolute paths to --stdin-filename.

[fd0]

Thanks for the report, it's a bug!

[garrmcnu]

As pointed out, the error is caused by the parent directories. The fs.Reader Lstat() method succeeds for the filename (e.g. /root/postgresql-dump.sql) but returns os.ErrNotExist for all of the parent directories (e.g. /root).
Lstat() currently only allows "/" and "." directories.

Updated Lstat() to also allow the parent directory components of the filename.

Not sure if it makes sense to also allow relative directory paths, given that the snapshot path is prepended with "/" so will always be absolute?