system/nxpkg: Make the storage root configurable and crash-safe.

[aviralgarg05]

Note: Please adhere to Contributing Guidelines.

Summary

This PR has been reduced to the storage layer. The rest of what it used to
contain is now in #3718, #3719 and #3720, in that order.

The package store, the catalog and the temporary download area were fixed
paths spread across /etc, /var/lib and /var/cache. A board rarely has
all three, and nothing let it put them somewhere it does have, such as a
removable card. They are now derived from CONFIG_SYSTEM_NXPKG_ROOT.

Every file the package manager owns was also written in place, so a reset
partway through a write left a truncated catalog or database behind. Writes
now go to a temporary file that is renamed into place.

Locking used only the file modification time. A card whose clock does not
follow CLOCK_REALTIME reports a file created a moment ago as decades old,
so a live lock looked stale to the next caller and was taken away from its
owner. Each lock now records a per-boot token and the owning task, so a
contender can tell a live owner from an abandoned one, and reclaims the
lock only in the second case.

Diagnostics go to syslog, since a package operation started by a supervisor
has no console to print to. pkg_runtime_compat() also falls back to
CONFIG_ARCH_BOARD_CUSTOM_NAME, because a board with a custom board
directory defines no CONFIG_ARCH_BOARD at all, which does not build.

Impact

• New feature: NO, this is the foundation the other three parts build on.
• User adaptation: YES. The storage root moves to
  CONFIG_SYSTEM_NXPKG_ROOT, default /var/lib/nxpkg. A board that mounts
  writable storage elsewhere sets that symbol.
• Build: NO.
• Hardware: NO.
• Documentation: The companion documentation is Documentation: Update nxpkg and add nxstore guide. nuttx#18875.
• Security: NO new boundary.
• Compatibility: A store created under the old fixed paths is not migrated;
  point CONFIG_SYSTEM_NXPKG_ROOT at the old location to keep it.

Testing

Build host: macOS 26.5, arm64, xtensa-esp-elf-gcc 14.2.0
(esp-14.2.0_20251107).

Target: Xtensa / ESP32-S3, Waveshare ESP32-S3-Touch-LCD-7.

• nxstyle, tools/checkpatch.sh, codespell and git diff --check on
  every changed file
• all system/nxpkg sources compiled for the target
• this part builds on master on its own; the three that follow declare it
  with Depends-On

On the target: a lock held by a running task was kept while a second caller
asked for it, and locks left by an exited task and by an earlier boot were
both reclaimed.

PR verification Self-Check

• This PR introduces one focused change.
• I have updated all required description fields above.
• I have reviewed and signed every commit.
• This PR adheres to the current contribution and coding guidelines.
• My PR is still work in progress.
• My PR is ready for review and can be safely merged.

[aviralgarg05]

Rebased onto current master (2aebae740) and squashed to a single commit.

The squash also removes an artefact of the previous history: the first commit added system/nxpkg/README.txt and a later commit removed it again after review, which made tools/checkpatch.sh fail on the intermediate commit while trying to resolve a path that no longer exists. All checks pass on the squashed commit.

The diff is limited to system/nxpkg/. Keeping this as a draft until I attach the full HTTP lifecycle transcript (sync, install, update, rollback, remove, and checksum rejection) from the ESP32-S3 target.

[linguini1]

This is a 2.5k LoC patch with 1 commit. Your PR lists a bunch of functionally different features in this PR (i.e adding an icon, adding SHA checks). Please split this into multiple commits, and ideally open a few PRs.

[acassis]

This is a 2.5k LoC patch with 1 commit. Your PR lists a bunch of functionally different features in this PR (i.e adding an icon, adding SHA checks). Please split this into multiple commits, and ideally open a few PRs.

I suggest dividing in more commit inside this PR, because he has already many PRs opened and the final evaluation date is arriving

[linguini1]

It won't make much difference except that the patches will be easier to review if split into many.

[aviralgarg05]

It won't make much difference except that the patches will be easier to review if split into many.

I will split and stack the PRs, it will be easy for review then

[linguini1]

Thank you Aviral!

[aviralgarg05]

Split as asked. This PR now carries only the storage layer, and the rest went into three follow-ups:

• system/nxpkg: Validate catalog and database contents before use. #3718 catalog and database validation
• system/nxpkg: Fetch the catalog and artifacts over the network. #3719 network fetch
• system/nxpkg: Complete the package lifecycle and command line. #3720 install lifecycle and command line

Each declares the one before it with Depends-On, so CI applies them in order. Only this one builds on master by itself, which is why it is first.

The content is unchanged from what you already reviewed; it is the same tree, cut into six commits across four PRs.

[xiaoxiang781216]

@aviralgarg05 sqaush your temp change into patch.

[halyssonJr]

@aviralgarg05,

Use this way:

git rebase -i HEAD~ N
git push origin your-branch -f

fixed