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emacs: resolve dlsym symbols in constructor to prevent clock_gettime deadlock - #281

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emacs: resolve dlsym symbols in constructor to prevent clock_gettime deadlock#281
edge-delta[bot] wants to merge 21 commits into
unstablefrom
fix/fixrand-dlsym-constructor

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@edge-delta edge-delta Bot commented Jun 20, 2026

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Summary

The clock_gettime interceptor in fixrand.c (introduced in PR #273) uses lazy-init dlsym(RTLD_NEXT, "clock_gettime") inside the function body. On some glibc versions, dlsym takes dl_load_lock and may internally invoke clock_gettime (e.g. for adaptive-mutex timing or CLOCK_MONOTONIC profiling), causing deadlock or infinite recursion on the very first call to the intercepted function.

This PR moves the dlsym resolution for both real_read and real_clock_gettime into an __attribute__((constructor)) function that runs at library load time (before any user code calls these functions), eliminating the re-entrancy hazard.

Related issues

Changes

  • Move real_read and real_clock_gettime function pointers from function-local statics to file-scope statics.
  • Add __attribute__((constructor)) static void fixrand_init(void) that resolves both symbols at library load time via dlsym(RTLD_NEXT, ...).
  • Remove lazy-init dlsym calls from inside read() and clock_gettime().
  • Add a defensive NULL check on real_read in read() (returns EIO) to handle the edge case where the constructor somehow failed.

Checklist

  • I've read CONTRIBUTING.md.
  • I've accepted the ICLA (and CCLA if contributing on my employer's time). CLA Assistant will prompt me on this PR if I haven't already.
  • min check passes for the affected packages/harnesses.
  • min patched-build <name> succeeds for any package I added or modified.
  • For new packages: source_provenance points to the canonical upstream and the source builds from source (not a prebuilt release binary) where the required toolchain is available.
  • For version bumps: I've verified the new sha256 against the upstream archive.

Notes for reviewers

This is complementary to PR #274 (which adds strtoll validation). PR #274 retains the in-function lazy-init dlsym pattern — this PR eliminates it entirely via a constructor.

The constructor pattern is the standard idiom for LD_PRELOAD shims that intercept widely-used glibc functions (cf. libfaketime, libeatmydata). It guarantees dlsym runs once, in a non-reentrant context, before any user code triggers the intercepted functions.

Compiled cleanly with gcc -shared -fPIC -O2 -ldl -Wall -Wextra — zero warnings.


This pull/merge request was created by Edge Delta AI Teammates — see #code-issues for the original conversation.

0chroma and others added 21 commits June 1, 2026 17:05
Add package for the Haskell Language Server (HLS), the official LSP
implementation for Haskell. Builds from source using GHC + Cabal with
dynamic linking, copying the binary and all required shared libraries
via ldd dependency resolution.

- Source: GitHub tag 2.14.0.0 with automatic extraction
- Build deps: base, cabal, ghc
- Runtime deps: glibc
- Network access enabled for cabal dependency index updates
- Includes standalone version check test
…package)

Info-ZIP unzip 6.0 has been frozen since 2009 and carries unfixed
CVE-2014-8139/8140/8141 + CVE-2018-1000035 (4 HIGH) with no upstream to track —
it was both vuln-exposed AND update-dark (pkgmgr check: no-source). bsdunzip,
added to libarchive in 3.7.0, is its maintained successor.

- New `packages/libarchive` (3.8.7, GithubRepo libarchive/libarchive, BSD-2):
  builds bsdtar/bsdcpio/bsdcat/bsdunzip + libarchive.so against zlib/bzip2/lzma
  (heavy optional backends disabled to keep the dep set lean). Source staged to
  gs://minimal-staging-archives/.

- `packages/unzip` becomes a thin compat shim: a /usr/bin/unzip symlink to
  bsdunzip (libarchive runtime dep). Info-ZIP source + build dropped. bsdunzip
  is a drop-in for the flags our callers use — verified in bsdunzip.1 that
  -o/-q/-d/-p are all supported, so bun + chromium-bin +
  chromium-headless-shell-bin keep invoking `unzip` unchanged. Version-tracking
  now follows libarchive, so it's no longer update-dark.

Locally validated: both build.ncl parse + resolve; `pkgmgr check --package
unzip` now reports up_to_date (3.8.7) instead of a `no-source` skip.

DRAFT — needs the buildbot to verify: libarchive compiles with the chosen
configure flags, bsdunzip is produced, the symlink + OutputBin lint pass, the
roundtrip test extracts via bsdunzip, and the three consumers (bun, chromium-bin,
chromium-headless-shell-bin) still build against bsdunzip.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The sandbox rejected the /usr/bin/unzip -> bsdunzip symlink: bsdunzip lives in
the libarchive package's output, so the symlink 'points outside output
directory'. Replace it with a /bin/sh wrapper that execs /usr/bin/bsdunzip
(provided by the libarchive runtime dep) — a real file, no symlink escape;
callers keep invoking unzip unchanged.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
…zip plan)

Reverses the bsdunzip migration: bun's build invokes `unzip -o -DD -d` and `-DD`
(don't-restore-timestamps) is an Info-ZIP-only flag bsdunzip lacks, so swapping
unzip→bsdunzip broke bun's build. Info-ZIP is the only impl with `-DD`.

Instead, do what every distro does — keep frozen Info-ZIP 6.0 and apply the
backported security patches. We were shipping the pristine `unzip_6.0.orig`
tarball with NO patches, which is exactly why it scanned 4 HIGH. Now stage +
apply Debian's full 6.0-29 series (31 patches): fixes CVE-2014-8139/8140/8141/
9636/9913, CVE-2015-7696/7697, CVE-2016-9844, CVE-2018-1000035, CVE-2019-13232,
CVE-2022-0529/0530 + build fixes. Patch 30 drops the K&R gmtime()/localtime()
declarations, replacing the manual sed that lived in build.sh.

Drops the new libarchive package (no remaining consumer). unzip stays
update-dark, which is correct: 6.0 is EOL and the patches are its maintenance.

Follow-up: VEX the patched CVE IDs so the version-based scanner (which can't see
the backported fixes) clears them.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
… edits)

The previous commit's git-add aborted on the already-removed libarchive
pathspec, so the build.ncl patches Source + build.sh apply-loop never staged.
This adds them: the staged-tarball Source and the series-apply loop (and removes
the now-redundant gmtime sed, handled by patch 30).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
mkromfs/pack_ps read SOURCE_DATE_EPOCH but then do
`if (!buildtime) buildtime = time(NULL)`, treating the sandbox's
SOURCE_DATE_EPOCH=0 (epoch 0 is falsy) as unset and falling back to
wall-clock time. That stamped a non-deterministic gs_romfs_buildtime into
usr/bin/gs. Fall back to time() only when SOURCE_DATE_EPOCH is genuinely
unset (base/mkromfs.c:2614, base/pack_ps.c:344).

Verified on aarch64: two from-scratch builds are byte-identical
(repro-check diff, 196/196 files).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
After the existing fixrand.so shim (getrandom/urandom), the dumped .pdmp
still differed in 11 bytes — two wall-clock timestamps read via
clock_gettime(CLOCK_REALTIME), which the shim didn't cover: the *scratch*
buffer's buffer-display-time (Fcurrent_time in make_initial_frame) and
Vgc_elapsed GC timing (src/alloc.c). Extend the shim to return
SOURCE_DATE_EPOCH for CLOCK_REALTIME (other clocks pass through).

Verified on aarch64: two from-scratch builds are byte-identical
(repro-check diff, 4282/4282 files).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
…hanges)

Adopts the hardening idea from the Edge Delta bot's #274 (cleanly — no
whole-file reindentation, executable bit preserved): verify the
'if (!buildtime)' pattern exists in both files before sed-ing, so a future
ghostscript that renames it fails the build instead of silently shipping a
non-reproducible binary.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
GHC's code output is already reproducible; the residual is metadata
ordering from hash-set iteration of package/UnitId collections:
1. link-arg/DT_NEEDED/.dynstr order — backport of upstream GHC #26838 /
   MR !15453 (sort preload1 in compiler/GHC/Unit/State.hs); Debian ships
   this exact patch for 9.10.3.
2. ghc-pkg package.cache — sort the .conf list before serialize in
   utils/ghc-pkg/Main.hs (no upstream fix; sort already imported).
Both guarded by grep so a future GHC source change fails the build loudly.
Fixing the compiler propagates to all downstream Haskell (stack, HLS).

DRAFT: Debian-proven + guarded, but not yet local build-twice-verified
(GHC is a multi-hour build_cost_multiple=6 build).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Per review on #277: patch (2) relies on 'sort' being in scope in
utils/ghc-pkg/Main.hs. 9.10.3 imports it (Main.hs:78), but add a grep
guard so a future GHC import reorg fails fast here rather than deep in
the multi-hour Hadrian build. Output-neutral; verified result unchanged.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Defensive NULL check before deref of real_clock_gettime: if
dlsym(RTLD_NEXT, "clock_gettime") ever returns NULL, fail with ENOSYS
instead of segfaulting. The CLOCK_REALTIME path already returns before
this point, so this only affects pass-through clocks (CLOCK_MONOTONIC,
etc.) — but it makes the shim robust regardless. Folds in the one valid
point from the Edge Delta bot's #278.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
A non-blocking pull_request check that, for each changed packages/*/build.ncl,
resolves the upstream release date (attrs.released_at override -> GitHub
releases/tags -> ftp.gnu.org Last-Modified -> unknown), computes age, and posts
a job-summary table flagging anything younger than a 7-day reference (the #20
minimum-soak criterion).

Report-only and additive: contents:read, no secrets, never fails the job, and
MUST be kept off branch-protection required checks. Its high-value output is the
live census of which packages have no derivable date and need attrs.released_at.

The attrs.released_at schema (minimal) + example + minimum_version bump are a
deliberate, deferred follow-up gated on sizing the backfill (see #20); the
script already handles released_at's absence gracefully, so this lands standalone.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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One low-severity diagnostic observation — no blocking issues found.

Comment thread packages/emacs/fixrand.c
Comment on lines +39 to +40
__attribute__((constructor))
static void fixrand_init(void) {

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Low severity / diagnostic concern: Neither dlsym call checks for failure or calls dlerror(). If resolution fails (e.g. in an unusual linker environment), real_read / real_clock_gettime stay NULL silently, and the fallback paths later return EIO / ENOSYS with no indication that the root cause is a failed symbol lookup.

Consider logging or aborting on failure here so issues are visible at load time rather than surfacing as cryptic runtime errors:

real_read = dlsym(RTLD_NEXT, "read");
real_clock_gettime = dlsym(RTLD_NEXT, "clock_gettime");
if (!real_read || !real_clock_gettime) {
    fprintf(stderr, "fixrand: dlsym failed: %s\n", dlerror());
    // optionally: abort();
}

Not a correctness bug (the NULL guards prevent crashes), but it would save debugging time if this library is ever loaded in an unexpected context.

@github-actions
github-actions Bot force-pushed the unstable branch 7 times, most recently from d25fb4c to 7222213 Compare June 21, 2026 03:00
@github-actions
github-actions Bot force-pushed the unstable branch 26 times, most recently from fcda2bd to 8574a4d Compare June 22, 2026 18:19
@bryan-minimal

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Thanks for all the help Edge Delta, we are working on them directly, closing out this advisory PR, we don't allow bots to do PRs unless they are our own for now.

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3 participants