cache: support *BSD

[williballenthin]

closes #2930

thanks @res2500

Checklist

• No CHANGELOG update needed

• No new tests needed

• No documentation update needed

• This submission includes AI-generated code and I have provided details in the description.

[github-actions]

Please add bug fixes, new features, breaking changes and anything else you think is worthwhile mentioning to the master (unreleased) section of CHANGELOG.md. If no CHANGELOG update is needed add the following to the PR description: [x] No CHANGELOG update needed

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the capa tool's compatibility by updating its cache directory detection mechanism. It specifically adds support for various *BSD operating systems, ensuring that the application correctly identifies and utilizes the appropriate cache location on these platforms. This change addresses a reported issue where capa might not have functioned optimally on *BSD systems due to incorrect cache path resolution.

Highlights

• Platform Support: Extended the get_default_cache_directory function to recognize and correctly handle *BSD operating systems (FreeBSD, OpenBSD, NetBSD, DragonflyBSD) for cache directory resolution.

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[gemini-code-assist]

Code Review

This pull request correctly extends cache directory support to *BSD systems by updating the platform check to include freebsd, openbsd, netbsd, and dragonfly. This improves cross-platform compatibility. I have one minor suggestion to improve code readability and maintainability.

CHANGELOG updated or no update needed, thanks! 😄

[mike-hunhoff]

Thanks @williballenthin !

[res2500]

Tested on FreeBSD 15.0. pkgsrc capa, good work
Output:

@res:~/Downloads $ capa -r capa-rules/ --signature sigs/ crek.exe
┌─────────────┬────────────────────────────────────────────────────────────────────────────────────┐
│ md5         │ 83242cefb305cc32a2a108d8614eb182                                                   │
│ sha1        │ 5249c83fc824236d5a092d1f0afd50050f8e6171                                           │
│ sha256      │ 9b5d86dd14d40edb38ae3751bf8807ae94d5cd9d524ff51ef9180462b7aa780e                   │
│ analysis    │ static                                                                             │
│ os          │ windows                                                                            │
│ format      │ pe                                                                                 │
│ arch        │ i386                                                                               │
│ path        │ /home/res2500/Downloads/crek.exe                                                   │
└─────────────┴────────────────────────────────────────────────────────────────────────────────────┘
┏━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
┃ ATT&CK Tactic        ┃ ATT&CK Technique                                                          ┃
┡━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩
│ DEFENSE EVASION      │ Obfuscated Files or Information::Indicator Removal from Tools [T1027.005] │
└──────────────────────┴───────────────────────────────────────────────────────────────────────────┘
┏━━━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
┃ MBC Objective            ┃ MBC Behavior                                                          ┃
┡━━━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩
│ ANTI-STATIC ANALYSIS     │ Executable Code Obfuscation::Argument Obfuscation [B0032.020]         │
│                          │ Executable Code Obfuscation::Stack Strings [B0032.017]                │
└──────────────────────────┴───────────────────────────────────────────────────────────────────────┘
┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
┃ Capability                              ┃ Namespace                                              ┃
┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩
│ contain obfuscated stackstrings         │ anti-analysis/obfuscation/string/stackstring           │
└─────────────────────────────────────────┴────────────────────────────────────────────────────────┘

res2500@res:~/Downloads $ uname -a
FreeBSD res 15.0-RELEASE FreeBSD 15.0-RELEASE releng/15.0-n280995-7aedc8de6446 GENERIC amd64
res2500@res:~/Downloads $ capa --version
capa 9.3.1

I'll also try this on NetBSD 10.1 and follow up if anything comes up.

[res2500]

NetBSD capa test elf32