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: golang/go#62392 (comment)

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 🙏