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fix(host/windows): merge host PUNKTFUNK_* env into the WGC helper's environment

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CreateProcessAsUserW gives the spawned helper the *user's* environment block, so
the host's PUNKTFUNK_ENCODER=nvenc (and ZEROCOPY/PERF/…) were dropped and the
helper fell back to the software (H.264-only) encoder — the client negotiated
H265 → "WGC helper exited". `merged_env_block` now parses the user block, strips
any PUNKTFUNK_* it carried, overlays this (host) process's PUNKTFUNK_* vars, and
passes the merged UTF-16 block.

Validated live on the RTX 4090 (host as SYSTEM): the helper spawns via
CreateProcessAsUserW, runs WGC with no hang (HDR FP16 BT.2020 PQ), opens NVENC
(D3D11 Main10), and relays AUs over the pipe — client-rs decoded 411 HEVC
Main-10 frames over the LAN. Step 4 (spawn + relay) complete.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This commit is contained in:
Enrico Bühler
2026-06-16 08:05:43 +00:00
parent 140209bbfc
commit 8d6cbb81fe
1 changed files with 47 additions and 5 deletions
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crates/punktfunk-host/src/capture/wgc_relay.rs
+47 -5
View File
@@ -152,6 +152,43 @@ unsafe fn no_inherit(h: HANDLE) {
let _ = SetHandleInformation(h, HANDLE_FLAG_INHERIT.0, HANDLE_FLAGS(0));
}
/// Build the helper's environment block: the user's block (so DLL/PATH/SystemRoot resolve) with this
/// (host) process's `PUNKTFUNK_*` vars overlaid, so the helper encodes with the SAME settings the
/// host runs with (`PUNKTFUNK_ENCODER=nvenc`, `PUNKTFUNK_ZEROCOPY`, …) instead of the user shell's.
/// Returns a UTF-16, double-null-terminated block suitable for `CREATE_UNICODE_ENVIRONMENT`.
unsafe fn merged_env_block(user_block: *const u16) -> Vec<u16> {
// Parse the user block ("VAR=VALUE\0" … "\0") into entries.
let mut entries: Vec<String> = Vec::new();
if !user_block.is_null() {
let mut p = user_block;
loop {
let mut len = 0isize;
while *p.offset(len) != 0 {
len += 1;
}
if len == 0 {
break; // the trailing empty string = end of block
}
let slice = std::slice::from_raw_parts(p, len as usize);
entries.push(String::from_utf16_lossy(slice));
p = p.offset(len + 1);
}
}
// Drop any PUNKTFUNK_* the user block carried, then overlay this process's PUNKTFUNK_* vars.
entries.retain(|e| !e.split('=').next().unwrap_or("").starts_with("PUNKTFUNK_"));
for (k, v) in std::env::vars().filter(|(k, _)| k.starts_with("PUNKTFUNK_")) {
entries.push(format!("{k}={v}"));
}
// Serialize back to a UTF-16 double-null-terminated block.
let mut block: Vec<u16> = Vec::new();
for e in entries {
block.extend(e.encode_utf16());
block.push(0);
}
block.push(0);
block
}
unsafe fn spawn_inner(cmdline: &str, w: u32, h: u32, hz: u32) -> Result<HelperRelay> {
// The user token of the active console session (requires the host to be SYSTEM).
let session = WTSGetActiveConsoleSessionId();
@@ -175,9 +212,17 @@ unsafe fn spawn_inner(cmdline: &str, w: u32, h: u32, hz: u32) -> Result<HelperRe
let _ = CloseHandle(user_token);
dup.context("DuplicateTokenEx(TokenPrimary)")?;
// The user's environment block (PATH, USERPROFILE, …) so the helper resolves config + DLLs.
// The user's environment block (PATH, USERPROFILE, SystemRoot → DLL resolution), MERGED with the
// host's PUNKTFUNK_* vars. CreateProcessAsUserW would otherwise give the helper the *user's* env
// only, dropping PUNKTFUNK_ENCODER=nvenc / PUNKTFUNK_ZEROCOPY/… that the host runs with — so the
// helper would fall back to the software (H.264-only) encoder. We parse the user block, strip any
// PUNKTFUNK_* it has, append the host's, and pass the merged block.
let mut env_block: *mut core::ffi::c_void = std::ptr::null_mut();
let _ = CreateEnvironmentBlock(&mut env_block, Some(primary), false);
let merged_env = merged_env_block(env_block as *const u16);
if !env_block.is_null() {
let _ = DestroyEnvironmentBlock(env_block);
}
// Three pipes: stdout (helper→host AUs), stdin (host→helper control), stderr (helper→host logs).
let (out_r, out_w) = make_pipe().context("stdout pipe")?;
@@ -211,7 +256,7 @@ unsafe fn spawn_inner(cmdline: &str, w: u32, h: u32, hz: u32) -> Result<HelperRe
None,
true, // inherit handles (the child's std ends)
CREATE_UNICODE_ENVIRONMENT | CREATE_NO_WINDOW,
Some(env_block),
Some(merged_env.as_ptr() as *const core::ffi::c_void),
None,
&si,
&mut pi,
@@ -221,9 +266,6 @@ unsafe fn spawn_inner(cmdline: &str, w: u32, h: u32, hz: u32) -> Result<HelperRe
let _ = CloseHandle(out_w);
let _ = CloseHandle(in_r);
let _ = CloseHandle(err_w);
if !env_block.is_null() {
let _ = DestroyEnvironmentBlock(env_block);
}
let _ = CloseHandle(primary);
if let Err(e) = created {