drm: second review pass on the phase-2 split

1- make PipeWire init atomic: build every per-display capturer into owned staging
first and publish them to CAP_DISPLAY_INFO only after all succeed, so a mid-loop
Capturer::new failure neither leaves partial entries (which the next check_init
would treat as already-initialized) nor leaks the raw pointers already created.
2- pin the immutable libdrmtap commit, not just the tag: git clone --branch
follows a mutable tag, so verify the cloned HEAD equals DRMTAP_SHA in both the CI
workflow and build.py, failing on a moved/compromised tag.
3- drop the stale comment claiming a libdrmtap-sys crate pin (the drm backend has
no such dependency).

.github/workflows/flutter-build.yml

@@ -1702,11 +1702,13 @@ jobs:
               # exported so build.py reuses the exact same source. We clone + build
               # the .so here and hand it to build.py via DRMTAP_PREBUILT_DIR, because
               # a later build step in this container disturbs the working tree.
-              # DRMTAP_REF is an EXACT release tag (vX.Y.Z), NOT a branch: the bundled
+              # DRMTAP_REF is an EXACT release tag (vX.Y.Z), NOT a branch, and it is verified
-              # .so version must match the `libdrmtap-sys = "=0.4.13"` crate pin in
+              # against the pinned immutable commit DRMTAP_SHA after clone (below). The drm backend
-              # libs/scrap/Cargo.toml (the loader only checks ABI-major). Bump both together.
+              # has NO libdrmtap-sys Cargo dependency: rustdesk dlopens this .so at runtime
+              # (drmtap_dl.rs checks ABI-major). Keep DRMTAP_SHA in sync with the tag on every bump.
               export DRMTAP_REPO="https://github.com/rustdesk-org/libdrmtap"
               export DRMTAP_REF="v0.4.13"
+              export DRMTAP_SHA="${DRMTAP_SHA:-c9cf0938f3b10a3d4a9eeb9c6f97aaa1606c6b4a}"
               # Guard: refuse a loose/branch ref so a moving `main` can never silently
               # regress the pin. Only an EXACT vX.Y.Z tag is accepted (a strict anchored
               # match, so values like v0.4.13-ci or a branch that resolves under
@@ -1718,6 +1720,13 @@ jobs:
               rm -rf third_party/libdrmtap
               git clone --depth 1 --branch "$DRMTAP_REF" "$DRMTAP_REPO" third_party/libdrmtap
               test -f third_party/libdrmtap/meson.build || { echo "FATAL: libdrmtap source missing"; exit 1; }
+              # Pin the immutable commit, not only the tag name: `git clone --branch` follows a
+              # mutable tag, so a moved or compromised v0.4.13 could swap the root-loaded .so while
+              # the regex above still passes. Verify the cloned HEAD is exactly the pinned SHA.
+              got_sha="$(git -C third_party/libdrmtap rev-parse HEAD)"
+              if [ "$got_sha" != "$DRMTAP_SHA" ]; then
+                echo "FATAL: libdrmtap $DRMTAP_REF resolved to $got_sha, expected $DRMTAP_SHA (moved/compromised tag?)"; exit 1
+              fi
               # Build libdrmtap.so now, while the cloned source is definitely
               # present, and stash the real object OUTSIDE the source tree. A later
               # build step in this container disturbs that working tree (it ends up

build.py

@@ -8,6 +8,7 @@ import zipfile
 import urllib.request
 import shutil
 import hashlib
+import subprocess
 import argparse
 import sys
 from pathlib import Path
@@ -342,6 +343,10 @@ def ffi_bindgen_function_refactor():
 # local testing or another fork.
 LIBDRMTAP_REPO = os.environ.get('DRMTAP_REPO', 'https://github.com/rustdesk-org/libdrmtap')
 LIBDRMTAP_REF = os.environ.get('DRMTAP_REF', 'v0.4.13')
+# The immutable commit the release tag must resolve to. `git clone --branch` follows a mutable tag,
+# so verifying this after clone catches a moved/compromised tag swapping the .so. Keep in sync with
+# LIBDRMTAP_REF on every bump (override via DRMTAP_SHA together with DRMTAP_REF for a local fork).
+LIBDRMTAP_SHA = os.environ.get('DRMTAP_SHA', 'c9cf0938f3b10a3d4a9eeb9c6f97aaa1606c6b4a')
 
 
 def _single_real_so(paths, where):
@@ -378,6 +383,12 @@ def build_libdrmtap_so():
             shutil.rmtree(src)
         os.makedirs(os.path.dirname(src), exist_ok=True)
         system2(f'git clone --depth 1 --branch {LIBDRMTAP_REF} {LIBDRMTAP_REPO} {src}')
+        got_sha = subprocess.check_output(
+            ['git', '-C', src, 'rev-parse', 'HEAD']).decode().strip()
+        if got_sha != LIBDRMTAP_SHA:
+            raise Exception(
+                f'libdrmtap {LIBDRMTAP_REF} resolved to {got_sha}, expected {LIBDRMTAP_SHA} '
+                f'(moved/compromised tag?)')
     build_dir = os.path.join(src, 'build-pkg')
     if not os.path.exists(os.path.join(build_dir, 'build.ninja')):
         system2(f'meson setup {build_dir} {src} --buildtype=release')

src/server/wayland.rs

@@ -249,14 +249,20 @@ pub(super) async fn check_init() -> ResultType<()> {
                     num_cpus::get()
                 );
 
-                // Create individual CapDisplayInfo for each display with its own capturer
+                // Create every per-display capturer FIRST into owned temporary storage, so a failure
+                // partway does not publish a partial set. If `Capturer::new` errors, the `?` returns
+                // and the already-staged capturers drop cleanly (no leaked raw pointers, and
+                // CAP_DISPLAY_INFO stays empty so the next check_init retries instead of seeing a
+                // non-empty map and skipping re-init).
+                let mut staged = Vec::with_capacity(num);
                 for (idx, display) in all.into_iter().enumerate() {
-                    let capturer =
+                    let capturer = Capturer::new(display)
-                        Box::into_raw(Box::new(Capturer::new(display).with_context(|| {
+                        .with_context(|| format!("Failed to create capturer for display {}", idx))?;
-                            format!("Failed to create capturer for display {}", idx)
+                    staged.push((idx, capturer));
-                        })?));
+                }
-                    let capturer = CapturerPtr(capturer);
+                // All capturers created: publish them atomically.
-
+                for (idx, capturer) in staged {
+                    let capturer = CapturerPtr(Box::into_raw(Box::new(capturer)));
                     let cap_display_info = Box::into_raw(Box::new(CapDisplayInfo {
                         rects: rects.clone(),
                         displays: displays.clone(),
@@ -265,14 +271,11 @@ pub(super) async fn check_init() -> ResultType<()> {
                         current: idx,
                         capturer,
                     }));
-
                     lock.insert(idx, cap_display_info as u64);
                 }
-                // Mark PipeWire initialized only AFTER every per-display capturer was created and
+                // Mark PipeWire initialized only AFTER the full set was published, so a partial
-                // stored. Setting it earlier meant a partial failure above (a `Capturer::new` error
+                // failure above leaves the flag false and the next check_init retries. This matters
-                // propagated by `?`) returned Err with the flag already true, so the next check_init
+                // more now that the per-display DRM->PipeWire fallback funnels through here.
-                // saw "initialized", skipped re-init, and left CAP_DISPLAY_INFO empty (no capture).
-                // This matters more now that the per-display DRM->PipeWire fallback funnels through here.
                 *PIPEWIRE_INITIALIZED.write().unwrap() = true;
             }
         }