[MESOS-4576] Introduce a stout helper for "which"

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.0.0
• Component/s: stout
• Labels: mesosphere
• Sprint: Mesosphere Sprint 29, Mesosphere Sprint 30
• Story Points: 2
• Assignee: Guangya Liu
• Reporter: Joseph Wu
• Created: 01/Feb/16 21:12
• Updated: 26/Nov/18 12:21
• Resolved: 26/Nov/18 12:21

Description

We may want to add a helper to stout/os.hpp that will natively emulate the functionality of the Linux utility which. i.e.

Option<string> which(const string& command)
{
  Option<string> path = os::getenv("PATH");

  // Loop through path and return the first one which os::exists(...).

  return None();
}

This helper may be useful:

• for test filters in src/tests/environment.cpp
• a few tests in src/tests/containerizer/port_mapping_tests.cpp
• the sha512 utility in src/common/command_utils.cpp
• as runtime checks in the LogrotateContainerLogger
• etc.

Issue Links

• relates to: MESOS-4454 Create common sha512 compute utility function.
• relates to: MESOS-4556 ShasumTest.SHA512SimpleFile failed on centos7.