libfaketime should depend on coreutils

[jsoref]

• [x] are reporting a bug others will be able to reproduce and not asking a question.
• [x] have a problem with brew install a single, official formula (not cask)?

  $ brew info libfaketime
  libfaketime: stable 0.9.7 (bottled), HEAD
  Report faked system time to programs
  https://github.com/wolfcw/libfaketime
  /usr/local/Cellar/libfaketime/0.9.7 (9 files, 93.4KB) *
  Poured from bottle on 2018-04-13 at 13:33:25
  From: https://github.com/Homebrew/homebrew-core/blob/master/Formula/libfaketime.rb
  ==> Requirements
  Required: macOS >= 10.7 ✔
  ==> Options
  --HEAD
  Install HEAD version

• [x] ran brew update and can still reproduce the problem?
• [x] ran brew doctor, fixed all issues and can still reproduce the problem?
• [x] ran brew gist-logs <formula> (where <formula> is the name of the formula that failed) and included the output link?

  $ brew gist-logs libfaketime
  Error: No logs.

• [x] if brew gist-logs didn't work: ran brew config and brew doctor and included their output with your issue?

To help us debug your issue please explain:

• What you were trying to do (and why) install and use faketime (libfaketime)

• What happened (include command output)

  $ brew install libfaketime
  ==> Downloading https://homebrew.bintray.com/bottles/libfaketime-0.9.7.high_sierra.bottle.tar.gz
  Already downloaded: /Users/jsoref/Library/Caches/Homebrew/libfaketime-0.9.7.high_sierra.bottle.tar.gz
  ==> Pouring libfaketime-0.9.7.high_sierra.bottle.tar.gz
  🍺  /usr/local/Cellar/libfaketime/0.9.7: 9 files, 93.4KB
  $ cp `which date` .
  $ faketime '2010-01-01 12:00:00Z' ./date
  Running (g)date failed: No such file or directory
  Error: Timestamp to fake not recognized, please re-try with a different timestamp.

• What you expected to happen The libfaketime package should depend on coreutils

• Step-by-step reproduction instructions (by running brew install commands)

  brew uninstall --force coreutils
  brew install libfaketime
  cp `which date` .
  faketime '2010-01-01 12:00:00Z' ./date

Note: on my system, coreutils was installed and linked, and thus faketime worked for me. When I had a colleague install libfaketime, faketime didn't work, because he hadn't installed coreutils. But, essentially libfaketime isn't functional without coreutils, and thus it should depend on it. For lack of a better reference: https://github.com/wolfcw/libfaketime/blob/c9a681c3e36c453affb7ff393458478a953d886c/src/faketime.c#L174

Manually "fixing" libfaketime can be achieved by: brew install coreutils as:

brew install coreutils

After which, this works:

$ faketime '2010-01-01 12:00:00Z' ./date
Fri Jan  1 07:00:00 EST 2010

Note: while my sample includes copying date to ., that's coincidental. Because of macOS's System Integrity Protection, one can't shim system programs. For our actual use case, we aren't shimming date, although we do copy the program we are shimming to a non protected directory in order to shim it.

[ilovezfs]

Are you saying it's incompatible with BSD date command? That sounds like an upstream porting issue to me.

[jsoref]

It requires gnu date. That's an upstream choice. And since it requires it, the brew formula needs to make gnu date available.

[jsoref]

https://github.com/wolfcw/libfaketime/blob/c9a681c3e36c453affb7ff393458478a953d886c/src/faketime.c#L54

[ilovezfs]

Please create an issue upstream about this as I'm not comfortable resorting to a coreutils dependency unless there's some reason the BSD date command cannot do what's needed, which is unlikely.

the brew formula needs to make gnu date available.

We could simply remove the faketime command as the library is still useful without it.

[jsoref]

@ilovezfs: in https://github.com/wolfcw/libfaketime/issues/158#issuecomment-381385252 @wolfcw indicates that a distinct package for faketime that depended on either a gdate or coreutils package seems reasonable.

How does that sound to you?

[ilovezfs]

@jsoref we'll just depend on coreutils. This is now fixed.