ENT-10961, CFE-1840: Files promise can now modify immutable bit in file system attributes

[larsewi]

TODO:

• handle content attribute
• handle copy_from attribute
• handle delete attribute
• handle edit_line attribute
• handle edit_xml attribute
• handle perms attribute
• handle touch attribute
• handle edit_template attribute
• handle acl attribute
• handle transformer attribute
• handle rename attribute

Is there any other ones that I've missed?

[cf-bottom]

Thank you for submitting a PR! Maybe @craigcomstock can review this?

[nickanderson]

MMM, the transformer attribute comes to mind.

  bundle agent __main__
  {
    files:
        "/tmp/example.txt"
          content => "Hello World";
  
        "/tmp/example.txt"
          transformer => "/usr/bin/gzip $(this.promiser)";
  
    reports:
        "$(with)" with => join( ",", lsdir( "/tmp", "example.*", "true" ));
  }

Looking at the files promise docs I imagine that create would also be affected:

bundle agent __main__
{
  vars:
      "check_file" string => "/tmp/check-file.txt";

  files:
      "$(check_file)"
        handle => "create_file",
        create => "true",
        if => "file_absent_report_kept";

   reports:
      "$(check_file) does not exist"
        classes => results( "namespace", "file_absent_report" );

      "$(check_file) was repaired"
        depends_on => { "create_file" };

      "$(check_file) exists"
        if => fileexists( "/tmp/check-file.txt" );
}

R: /tmp/check-file.txt does not exist
R: /tmp/check-file.txt was repaired
R: /tmp/check-file.txt exists

And the delete attribute would seem to be affected as well.

And rename too

bundle agent __main__
{
  files:
    "/tmp/example.txt"
      content => "Disable me!";

    "/tmp/example.txt"
      rename => default:disable;
}
# For reference:
# body rename disable
# # @brief Disable the file
# {
#         disable => "true";
# }

   info: Created file '/tmp/example.txt', mode 0600
   info: Updated file '/tmp/example.txt' with content 'Disable me!'
warning: File object '/tmp/example.txt' exists, contrary to promise
   info: Changed permissions of '/tmp/example.txt' to 'mode 0600'
   info: Disabled file '/tmp/example.txt' by renaming to '/tmp/example.txt.cfdisabled' with mode 0600

I added them to the description.

[larsewi]

@cf-bottom Jenkins with exotics please :)

[cf-bottom]

Alright, I triggered a build:

(with exotics)

Jenkins: https://ci.cfengine.com/job/pr-pipeline/12188/

Packages: http://buildcache.cfengine.com/packages/testing-pr/jenkins-pr-pipeline-12188/

[cf-bottom]

Sure, I triggered a build:

(with exotics)

Jenkins: https://ci.cfengine.com/job/pr-pipeline/12284/

Packages: http://buildcache.cfengine.com/packages/testing-pr/jenkins-pr-pipeline-12284/

[craigcomstock]

Looks good! A high-level question about atomicity and maybe one typo. :)

[craigcomstock]

I think you should change the orig file to immutable just before this copy. Not 100% atomic but pretty close so that between this Begin() and the Commit() no one else can "easily" modify the file without also modifying the immutable bit of course.

[craigcomstock]

Here it seems that we should have something like:

OverrideImmutableBegin(struct utimbuf *times) to capture the modified/access times when we begin the "transaction"

Also, during this Begin() we should make the file immutable to attempt to restrict access as much as possible while we do "work" and before we call Commit().

And then OverrideImmutableCommit() takes that as a parameter and if the original file has changed mod/access since Begin() we should fail to commit saying that the file changed inside of the window of time of the transaction to modify the immutable file.

[craigcomstock]

Suggested change

	/* Here we only handle the clearing of the immutable the immutable
	/* Here we only handle the clearing of the immutable

[craigcomstock]

Suggested change

	* by temporarily clearing it when ever needed. */
	* by temporarily clearing it whenever needed. */

[craigcomstock]

So this is our "menu" item list for an attribute right? Is this required and if not, defaulted to "default"? I will probably find out later in the review. :)