CPack External generator runs CPACK_EXTERNAL_PACKAGE_SCRIPT before creating JSON metadata

Usage
1

Hi.

I’m having some trouble understanding how the CPack external generator is supposed to work. I’m running CPack via the CMake “package” target. In CMake I’m setting CPACK_EXTERNAL_PACKAGE_SCRIPT to point to a CMake script that invokes an external tool using execute_process. I want the external process to read the metadata from the CPack generated JSON file and use it to package my library. However, when I run a clean build, the external script runs before the JSON metadata is created causing my packaging step to fail. Is there a way to instruct CPack to generate the JSON metadata before my external script is executed?

Thanks.

2

It looks like the package.json is written out before the script is executed. Could you get a trace of why the package.json is disappearing perhaps?

3

A long time has passed since the OP, but I’m seeing the same problem, when running the CPACK_EXTERNAL_PACKAGE_SCRIPT the JSON metadata file is present, but with partial contents. Running the same script later/manually works without problems i.e. after cpack has finished. I also tried just copying the JSON metadata file to another location at that point and it has partial content at that time.

Could there be some race condition/file flush issue making the script run before the JSON metadata file is fully completed and/or flushed to disk?

4

We see the same issue here. @ben.boeckel , it’s not that the file does not exist, it does but as @t1-nva mentions it is not complete, like it has not been fully flushed.

In our case it just ends like so:

   ⋮

    "tests" : 
    {
      "archiveFile" : "",
      "dependencies" : [],
      "description" : "",
      "displayName" : "Unit Tests",
      "group" : "Development",
      "installationTypes" : [],
      "isDisabledByDefault" : true,
      "isDownloaded" : false,
      "isHidden" : true,
      "isRequired" : false,
      "name" : "tests"
    }
  },
  "errorOnAbsoluteInstallDes

so it ends right in the middle of a word and is thus not even valid json.

5

Ah, that makes the problem a lot clearer, thanks for the extra details. Can you test this patch: https://gitlab.kitware.com/cmake/cmake/-/merge_requests/9669

1 Like
6

In CMake 3.30.2 this issue has been fixed and CMAKE_EXTERNAL_PACKAGE_SCRIPT is working as expected!

Thanks a lot!