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fix: avoid vfork stack corruption and x86-64 charset abort #27

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fix: avoid vfork stack corruption and x86-64 charset abort #27

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b502271
fix: stop interposing vfork in Plex process
Sep 26, 2026
7171fb7
fix: redirect ASCII codecvt to UTF-8 on x86-64
Sep 26, 2026
1320342
fix: allow strict migration counters under errexit
Sep 26, 2026
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27 changes: 3 additions & 24 deletions rust/plex-pg-core/src/pms_process_compat.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,9 @@ use crate::db_interpose_common;
use crate::db_interpose_common::stderr_ptr;
use crate::env_utils;

// Do not interpose vfork. Until the child execs, it shares the parent's stack;
// returning through a Rust wrapper can corrupt the suspended caller's frame.

type CloneStartFn = unsafe extern "C" fn(*mut libc::c_void) -> c_int;
type CloneFn = unsafe extern "C" fn(
Option<CloneStartFn>,
Expand Down Expand Up @@ -39,7 +42,6 @@ type SyscallFn = unsafe extern "C" fn(
libc::c_long,
libc::c_long,
) -> libc::c_long;
type VForkFn = unsafe extern "C" fn() -> libc::pid_t;

static mut ORIG_DAEMON: Option<DaemonFn> = None;
static mut ORIG_FORK: Option<ForkFn> = None;
Expand All @@ -48,7 +50,6 @@ static mut ORIG_PRCTL: Option<PrctlFn> = None;
static mut ORIG_PTHREAD_SETNAME_NP: Option<PthreadSetnameNpFn> = None;
static mut ORIG_SETSID: Option<SetsidFn> = None;
static mut ORIG_SYSCALL: Option<SyscallFn> = None;
static mut ORIG_VFORK: Option<VForkFn> = None;

static PROCESS_COMPAT_LOG_BUDGET: AtomicI32 = AtomicI32::new(0);
static SUPPRESS_DAEMON: AtomicI32 = AtomicI32::new(0);
Expand Down Expand Up @@ -117,10 +118,6 @@ unsafe fn resolve_syscall() -> Option<SyscallFn> {
resolve_symbol(&mut ORIG_SYSCALL, b"syscall\0")
}

unsafe fn resolve_vfork() -> Option<VForkFn> {
resolve_symbol(&mut ORIG_VFORK, b"vfork\0")
}

unsafe fn set_errno(err: c_int) {
*libc::__errno_location() = err;
}
Expand Down Expand Up @@ -370,24 +367,6 @@ pub unsafe extern "C" fn clone(
rc
}

#[no_mangle]
/// # Safety
/// ABI interposition wrapper for `vfork`. Callers must obey libc preconditions.
pub unsafe extern "C" fn vfork() -> libc::pid_t {
let Some(orig) = resolve_vfork() else {
set_errno(libc::ENOSYS);
return -1;
};

let rc = orig();
if rc > 0 {
maybe_log_event(b"vfork\0", i64::from(rc), 0);
} else if rc < 0 {
maybe_log_event(b"vfork\0", -1, *libc::__errno_location());
}
rc
}

#[no_mangle]
/// # Safety
/// ABI interposition wrapper for `prctl`. Callers must obey libc preconditions.
Expand Down
37 changes: 37 additions & 0 deletions rust/plex-pg-core/src/runtime_linux.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -525,6 +525,43 @@ static INIT: extern "C" fn() = shim_init_wrapper;
#[cfg_attr(target_os = "linux", link_section = ".fini_array")]
static FINI: extern "C" fn() = shim_cleanup_wrapper;

// ────────────────────────────────────────────────────────────────────────────
// The bundled x86-64 Boost codecvt also rejects the "ASCII" name. Preserve
// the C++ hidden return pointer in rdi and tail-call the UTF-8 variant with
// its two explicit arguments (locale in rsi, facet moved from ecx to edx).
#[cfg(all(feature = "interpose", target_arch = "x86_64"))]
std::arch::global_asm!(
".global _ZN5boost6locale4util21create_simple_codecvtERKNSt3__26localeERKNS2_12basic_stringIcNS2_11char_traitsIcEENS2_9allocatorIcEEEENS0_12char_facet_tE",
".type _ZN5boost6locale4util21create_simple_codecvtERKNSt3__26localeERKNS2_12basic_stringIcNS2_11char_traitsIcEENS2_9allocatorIcEEEENS0_12char_facet_tE, @function",
"_ZN5boost6locale4util21create_simple_codecvtERKNSt3__26localeERKNS2_12basic_stringIcNS2_11char_traitsIcEENS2_9allocatorIcEEEENS0_12char_facet_tE:",
"cmp byte ptr [rdx], 65",
"jne .Lshim_x86_csc_orig",
"cmp byte ptr [rdx + 1], 83",
"jne .Lshim_x86_csc_orig",
"cmp byte ptr [rdx + 2], 67",
"jne .Lshim_x86_csc_orig",
"cmp byte ptr [rdx + 3], 73",
"jne .Lshim_x86_csc_orig",
"cmp byte ptr [rdx + 4], 73",
"jne .Lshim_x86_csc_orig",
"cmp byte ptr [rdx + 5], 0",
"jne .Lshim_x86_csc_orig",
"mov r11, qword ptr [rip + SHIM_CREATE_UTF8_CODECVT_PTR@GOTPCREL]",
"mov r11, qword ptr [r11]",
"test r11, r11",
"je .Lshim_x86_csc_orig",
"mov edx, ecx",
"jmp r11",
".Lshim_x86_csc_orig:",
"mov r11, qword ptr [rip + SHIM_CREATE_SIMPLE_CODECVT_PTR@GOTPCREL]",
"mov r11, qword ptr [r11]",
"test r11, r11",
"je .Lshim_x86_csc_abort",
"jmp r11",
".Lshim_x86_csc_abort:",
"jmp abort@PLT",
);

// ────────────────────────────────────────────────────────────────────────────
// ────────────────────────────────────────────────────────────────────────────
// AArch64 assembly hook for boost::locale::util::create_simple_codecvt.
Expand Down
7 changes: 4 additions & 3 deletions scripts/migrate_lib.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -199,7 +199,8 @@ migrate_sqlite_to_pg() {

if [[ -z "$pg_cols" ]]; then
echo -e "${YELLOW}SKIP (no PG table)${NC}"
((skipped++))
# Prefix increment succeeds when this script runs under set -e.
((++skipped))
continue
fi

Expand Down Expand Up @@ -276,10 +277,10 @@ migrate_sqlite_to_pg() {
if python3 "$migrate_py" \
"$SQLITE_DB" "$table" "$sqlite_select" "$pg_cols_list" "$schema" 2>>"$log_dir/migration_errors.log"; then
echo -e "${GREEN}OK${NC}"
((migrated++))
((++migrated))
else
echo -e "${RED}FAIL${NC}"
((failed++))
((++failed))
fi

# Restore check constraints and triggers
Expand Down