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17d6207bf5
PR #396's X2 dry-run caught a wheel-import failure on the manylinux_2_28 floor matrix entry (both x86_64 and aarch64). Same class as #355: ImportError: ... undefined symbol: __libc_single_threaded `__libc_single_threaded` is a single-byte char added in glibc 2.32. Newer libstdc++ (gcc 11+) reads it inside `__cxa_thread_atexit_impl` to elide locking on the single-threaded fast path. ORT prebuilt static archives compiled with gcc-14.2.1 against glibc-2.38+ headers bake in the reference. Users with glibc < 2.32 hit ImportError on `import headroom._core`. Latent since the ORT artifact bump that started using gcc 14. X1 is the gate that catches it at release time; X2 caught it at PR time — exactly as designed. Fix: 1. glibc_compat.c adds Section B: `char __libc_single_threaded = 0;` Setting to 0 (multi-threaded) is safe; libstdc++ takes the locked slow path. Setting to 1 would race in any multithreaded Rust wheel. 2. build.rs adds `-Wl,-u,__libc_single_threaded` so the shim's archive members are pulled regardless of scan order. 3. audit_wheel_glibc_symbols.py POST_FLOOR_SYMBOLS adds the new symbol — verified locally: the audit now rejects the failing PR #396 wheel with the right message.
77 lines
3.5 KiB
Rust
77 lines
3.5 KiB
Rust
// Compile a tiny C shim that provides local definitions of glibc
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// symbols introduced after the manylinux_2_28 floor that our static
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// deps reference:
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//
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// - C23 strtol family (`__isoc23_strtol`, `__isoc23_strtoll`, ...)
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// introduced in glibc 2.38 — see `glibc_compat.c` Section A.
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// - `__libc_single_threaded` introduced in glibc 2.32 — see
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// `glibc_compat.c` Section B (caught by X1 smoke gate on PR
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// #396 X2 dry-run; latent since the ORT artifact bump).
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//
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// Static dependencies in `_core.so` (notably the prebuilt ONNX
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// Runtime artifacts compiled with gcc 14.x) reference all of these,
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// so without this shim the wheel fails to import on user machines
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// whose system glibc is below the build host's. The shim is
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// Linux/glibc-only — macOS, Windows, and musl don't ship glibc and
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// don't reference any of these symbols.
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//
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// Issues:
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// - #355 (https://github.com/chopratejas/headroom/issues/355)
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// for the `__isoc23_*` family
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// - PR #396 dry-run for the `__libc_single_threaded` symbol
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fn main() {
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println!("cargo:rerun-if-changed=glibc_compat.c");
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println!("cargo:rerun-if-changed=build.rs");
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// The shim is glibc-specific. Skip on every other target: macOS
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// uses Darwin libc, Windows has MSVCRT, musl handles strtoll
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// identically and never emits __isoc23_* / __libc_single_threaded.
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let target_os = std::env::var("CARGO_CFG_TARGET_OS").unwrap_or_default();
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let target_env = std::env::var("CARGO_CFG_TARGET_ENV").unwrap_or_default();
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if target_os != "linux" || target_env != "gnu" {
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return;
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}
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cc::Build::new()
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.file("glibc_compat.c")
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// -fPIC because we link into a cdylib. -O2 for size — the
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// file is ~10 lines but every byte counts in a wheel that's
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// already 35 MiB.
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.flag_if_supported("-fPIC")
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.opt_level(2)
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.compile("headroom_glibc_compat");
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// Force the linker to pull our shim's objects into _core.so even
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// if at archive-scan time no UND `__isoc23_*` reference exists
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// yet. Without this, the ORT prebuilt static archives — which
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// are downloaded by ort-sys and link AFTER our shim's archive
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// on aarch64 (observed in PR #386's release run) — leave the
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// `__isoc23_*` references unresolved at the .so level even
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// though our archive defines them. The audit then rightly
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// rejects the wheel.
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//
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// `-u <sym>` (a.k.a. `--undefined`) tells the linker: "treat
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// this symbol as undefined at the start of linking, which forces
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// any archive defining it to be scanned and its members pulled
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// in." Once our archive's objects are in, the shim's strong
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// definitions are present in `_core.so` and ORT's later
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// references resolve to them. On x86_64 the ORT archive
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// happened to scan first; on aarch64 it did not, so this gate
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// is the load-bearing fix that makes the shim work uniformly.
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for sym in [
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"__isoc23_strtol",
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"__isoc23_strtoll",
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"__isoc23_strtoul",
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"__isoc23_strtoull",
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// glibc 2.32+ — see glibc_compat.c Section B. Force-undefined
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// here for the same reason as the __isoc23_* family: archives
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// that DEFINE the symbol must be scanned before archives that
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// REFERENCE it, otherwise our shim's archive is dropped and
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// the .so ships with a UND `__libc_single_threaded` that
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// breaks import on glibc < 2.32.
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"__libc_single_threaded",
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] {
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println!("cargo:rustc-link-arg=-Wl,-u,{sym}");
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}
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}
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