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docs: update assessment — S1-S4 all implemented, remove stale 'no implementation' claims

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Vasilito
2026-05-05 21:59:45 +01:00
parent cfe9d70e47
commit 0a81b7e1e9
1 changed files with 9 additions and 11 deletions
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local/docs/RELIBC-AGAINST-GLIBC-ASSESSMENT.md
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@@ -20,18 +20,16 @@ EFD_NONBLOCK = 00004000 // octal 0x800
glibc calls `INLINE_SYSCALL(eventfd2, 2, initval, flags)` — a kernel syscall. The kernel creates an anonymous file descriptor for event notification. Supports `EFD_SEMAPHORE` (semaphore-like counting), `EFD_CLOEXEC`, `EFD_NONBLOCK`.
### relibc current state
### relibc current state (updated 2026-05-05 — S1-S4 implemented)
```rust
// src/header/sys_eventfd/mod.rs — 8 lines
pub const EFD_SEMAPHORE: c_int = 1;
pub const EFD_CLOEXEC: c_int = 0x80000;
pub const EFD_NONBLOCK: c_int = 0x800;
// No eventfd() function — constants only
// src/header/sys_eventfd/mod.rs — 30 lines
// Full eventfd() implementation with EFD_SEMAPHORE/CLOEXEC/NONBLOCK.
// Opens scheme:event/eventfd/{initval}/{sem} via Sys::open.
```
**Constants match** ✅
**No implementation** ❌ — libwayland provides inline `eventfd()` via `/scheme/event`
**Implementation shipped** ✅
**Kernel support**: `P0-eventfd-kernel.patch` extends event scheme with eventfd path parsing ✅
### Gaps
@@ -129,9 +127,9 @@ glibc uses a sophisticated named semaphore implementation:
| Gap | Severity | Detail |
|-----|----------|--------|
| **No name canonicalization** | Medium | Names go directly to `shm_open` without prefix/suffix. glibc uses `/dev/shm/sem.NAME` |
| **No existing mapping reuse** | High | Every `sem_open` creates a NEW mmap even if already open. Wasteful and races with `sem_close` on shared references |
| **No refcounting** | High | `sem_close` unconditionally munmaps. If two threads open the same semaphore, one close breaks the other |
| **No name canonicalization** | ~~Medium~~ ✅ FIXED | Names now prefixed with `sem.` before `shm_open`. glibc uses `/dev/shm/sem.NAME` equivalent. |
| **No existing mapping reuse** | ~~High~~ ✅ FIXED | Global `BTreeMap<String, NamedSemEntry>` with `AtomicUsize` refcount. `sem_open` reuses existing mappings, increments refcount. |
| **No refcounting** | ~~High~~ ✅ FIXED | `sem_close` decrements `AtomicUsize`, munmaps only when zero. |
| **No cancellation safety** | Low | No `pthread_setcancelstate` around file ops |
| **va_list not parsed** | Medium | `sem_open` hardcodes `value=0` when O_CREAT, ignoring mode and initial value from varargs |
| **No `__sem_check_add_mapping` equivalent** | High | Opens named sem every time instead of reusing existing mapping |