Flaky checks on STDIN for purl provider

[sfc-gh-ylefloch]

What happened:

I tried to run Grype for a single package coming from stdin:

> echo "pkg:rpm/some-rpm" | grype purl:/dev/stdin
failed to catalog: purl file is empty: /dev/stdin

This works on OSX, but not in a Linux container.

What you expected to happen:

The scanning happens as normal on all platforms.

How to reproduce it (as minimally and precisely as possible):

Running the example command above on Linux.

Anything else we need to know?:

That is the same problem as there: https://github.com/golang/go/issues/62392#issuecomment-1702010687

Because there is a check in Grype for the size of the input file, which could be stdin. The behaviour of Size() is system-dependent according to the std docs.

I recommend getting rid of fileHasContent() entirely, since it's only used by the purl provider and doesn't have a reliable behaviour.

Environment:

• Output of grype version for OSX:

  Application:         grype
  Version:             0.82.0
  BuildDate:           2024-10-07T21:20:18Z
  GitCommit:           brew
  GitDescription:      [not provided]
  Platform:            darwin/arm64
  GoVersion:           go1.23.2
  Compiler:            gc
  Syft Version:        v1.14.0
  Supported DB Schema: 5

• Output of grype version for Linux:

  Application:         grype
  Version:             0.82.0
  BuildDate:           2024-10-07T21:36:44Z
  GitCommit:           6b09bb857564cd3c59c0cc1b6ea997c5ee198b6d
  GitDescription:      v0.82.0
  Platform:            linux/amd64
  GoVersion:           go1.23.2
  Compiler:            gc
  Syft Version:        v1.14.0
  Supported DB Schema: 5

• OS (e.g: cat /etc/os-release or similar): OSX 14.6.1 / Debian 12

[sfc-gh-ylefloch]

Thank you @wagoodman 🙏