Support aarch64-unknown-linux-ohos (HarmonyOS): utmpx/fsext/hostid fixes and timezone pass-through

[YodonTan]

Support aarch64-unknown-linux-ohos (HarmonyOS): utmpx/fsext/hostid fixes and timezone pass-through

Background

HarmonyOS (OpenHarmony-based, aarch64-unknown-linux-ohos) ships toybox as its system toolset. Compared with the GNU coreutils set (108 commands, which uutils mirrors 1:1), the on-device toybox provides 83 and lacks 25: arch, b2sum, base32, basenc, csplit, dir, dircolors, fold, hostid, join, numfmt, pathchk, pinky, pr, ptx, runcon, sha224sum, shuf, stdbuf, stty, sum, tsort, unexpand, users, vdir. (runcon/chcon belong to the SELinux domain and are intentionally not built — OHOS has no SELinux.)

This change is the minimal patch set required to build uutils/coreutils natively on HarmonyOS (cargo build --no-default-features --features feat_os_unix and make build both pass, verified on a HarmonyOS PC, kernel HongMeng 1.13.0 aarch64).

Patch summary (verified root causes)

File	Root cause	Change
src/uucore/src/lib/features/utmpx.rs	OHOS libc has no glibc-prefixed __UT_HOSTSIZE/__UT_LINESIZE/__UT_NAMESIZE constants; the OHOS SDK libc.so no longer exports setutxent/getutxent/endutxent/utmpxname (linker: undefined symbol)	Route OHOS through the musl (UT_*) constant branch; provide same-signature stub functions (no-op / null, identical musl semantics) gated by #[cfg(target_env = "ohos")]. Existing musl allow(deprecated) attributes and all non-OHOS paths are untouched.
src/uucore/src/lib/features/fsext.rs	statfs.f_type is u64 on OHOS (musl-like libc), falling into the i64 branch → E0308	Include OHOS in the musl try_into().unwrap() branch.
src/uu/hostid/src/hostid.rs	gethostid is not exported by the OHOS SDK libc	OHOS-local implementation: read /etc/hostid, else FNV-1a hash of the hostname (glibc semantics). Non-OHOS keeps libc::gethostid.
src/uu/date/src/date.rs	jiff's TimeZone::try_system() only reads /etc/localtime / zoneinfo dirs, none exist on OHOS → always falls back to UTC (±0 offset vs system +08:00)	OHOS-only ohos_system_zone(): pass through the system time zone ID from OH_TimeService_GetTimeZone and resolve it via embedded IANA tzdata (jiff-tzdb) with TimeZone::tzif, preserving DST rules and historical transitions. Call sites are #[cfg(target_env = "ohos")]-gated; non-OHOS code paths are byte-identical to upstream.
src/uu/date/Cargo.toml	jiff needs tzdata to resolve the ID	[target.'cfg(target_env = "ohos")'.dependencies] jiff-tzdb = "0.1" (OHOS-only).
Cargo.lock	new dependency	+ jiff-tzdb (repo tracks the lockfile).

Build

Standard upstream flow, unix default feat_os_unix (96 commands; no selinux/systemd_logind):

export PATH="$HOME/.bitfun-ccshim:$HOME/.harmonybrew/bin:$PATH"   # cc→OHOS clang, ar→llvm-ar
make build      # per-command binaries → target/debug/<cmd>
make build MULTICALL=y   # multi-call → target/debug/coreutils

Verification (on-device, all passed)

Check	Command	Expected
System timezone	date "+%F %T %z %Z"	matches system date: +0800 CST
tzdata DST history	date -d 1987-06-01 "+%z %Z"	+0900 CDT (China DST era 1986–1991)
Missing commands	printf 'hello coreutils for HOS' | b2sum	128 hex
Negative (utmpx stub)	who; users	empty output (no utmp data source on OHOS, graceful degradation)
SELinux	runcon	not built (no SELinux on OHOS)

Known limitations (runtime degradation, not regressions)

• who/uptime/users/pinky: OHOS keeps no login session records; the utmpx stubs yield empty results (uptime still reads /proc).
• cp --preserve: sandbox restricts xattr/timestamp writes; uutils reports strictly (toybox silently skips).
• System dirs like / are subject to the app-sandbox read restrictions.

Implementation

In fork YodonTan/coreutils, branch ohos-pr (single commit 85de24e1c) — code only; documentation lives in this issue and the PR. Happy to iterate on CI (a aarch64-unknown-linux-ohos workflow would mirror android.yml/freebsd.yml).