Avoid deadlocks after fork

[danth]

Fork only copies the current thread, so from that point on we could deadlock if we access anything that was locked by another thread at the time of the fork.

According to man 2 fork we should only use async signal safe functions between fork and execve.

[github-actions]

License Check Results

🚀 The license check job ran with the Bazel command:

bazel run --lockfile_mode=error //:license-check

Status: ⚠️ Needs Review

Click to expand output

[License Check Output]
Extracting Bazel installation...
Starting local Bazel server (8.6.0) and connecting to it...
INFO: Invocation ID: 63381e2f-9846-4148-9917-bf0885655cad
Computing main repo mapping: 
Computing main repo mapping: 
Loading: 
Loading: 0 packages loaded
Loading: 0 packages loaded
Loading: 0 packages loaded
    currently loading: 
Loading: 0 packages loaded
    currently loading: 
Loading: 0 packages loaded
    currently loading: 
Analyzing: target //:license-check (1 packages loaded, 0 targets configured)
Analyzing: target //:license-check (1 packages loaded, 0 targets configured)

Analyzing: target //:license-check (34 packages loaded, 10 targets configured)

Analyzing: target //:license-check (85 packages loaded, 10 targets configured)

Analyzing: target //:license-check (141 packages loaded, 2459 targets configured)

Analyzing: target //:license-check (151 packages loaded, 5480 targets configured)

Analyzing: target //:license-check (152 packages loaded, 5571 targets configured)

Analyzing: target //:license-check (163 packages loaded, 8263 targets configured)

Analyzing: target //:license-check (164 packages loaded, 8271 targets configured)

Analyzing: target //:license-check (164 packages loaded, 8271 targets configured)

Analyzing: target //:license-check (164 packages loaded, 8271 targets configured)

Analyzing: target //:license-check (167 packages loaded, 10159 targets configured)

Analyzing: target //:license-check (168 packages loaded, 10283 targets configured)

INFO: Analyzed target //:license-check (169 packages loaded, 10409 targets configured).
[13 / 16] JavaToolchainCompileClasses external/rules_java+/toolchains/platformclasspath_classes; 0s disk-cache, processwrapper-sandbox
[14 / 16] JavaToolchainCompileBootClasspath external/rules_java+/toolchains/platformclasspath.jar; 0s disk-cache, processwrapper-sandbox
INFO: Found 1 target...
Target //:license.check.license_check up-to-date:
  bazel-bin/license.check.license_check
  bazel-bin/license.check.license_check.jar
INFO: Elapsed time: 24.280s, Critical Path: 2.56s
INFO: 16 processes: 12 internal, 3 processwrapper-sandbox, 1 worker.
INFO: Build completed successfully, 16 total actions
INFO: Running command line: bazel-bin/license.check.license_check ./formatted.txt <args omitted>
usage: org.eclipse.dash.licenses.cli.Main [-batch <int>] [-cd <url>]
       [-confidence <int>] [-ef <url>] [-excludeSources <sources>] [-help] [-lic
       <url>] [-project <shortname>] [-repo <url>] [-review] [-summary <file>]
       [-timeout <seconds>] [-token <token>]

[github-actions]

The created documentation from the pull request is available at: docu-html

[danth]

Tests failed due to a network error.

[danth]

New implementation considering previous feedback:

• Use a separate function, not the assertion handler, so it cannot be swapped out for something unsafe
• Use signal safe implementations of strerror, otherwise fall back to printing the raw error number
• Build the error message in a fixed size buffer to avoid allocations and multiple writes
• Comments on all affected functions to avoid later changes making this unsafe again
• Minimal diff to aid review