Merge bitcoin/bitcoin#36218: build: avoid `pipe2` on Darwin (for now)
What the developer wrote
Authored by merge-script
Merge bitcoin/bitcoin#36218: build: avoid `pipe2` on Darwin (for now)
9c7748315d3124d1abe6a4606743cd9274beee66 build: avoid pipe2 on Darwin (for now) (fanquake)
Pull request description:
macOS 27 will support `pipe2` at runtime, and Xcode 27 (and Command Line Tools) support it at compile time. This means a macOS < 27 system will detect support for `pipe2`, but then binaries will crash at runtime, as pipe2 is not available.
Just avoid `pipe2` on macOS for now, and continue using `pipe`. Note that the compilation also produces availability warnings:
```bash
[415/1121] Building CXX object src/util/CMakeFiles/bitcoin_util.dir/tokenpipe.cpp.o
../src/util/tokenpipe.cpp:89:9: warning: 'pipe2' is only available on macOS 27.0 or newer [-Wunguarded-availability-new]
89 | if (pipe2(fds, O_CLOEXEC) != 0) {
| ^~~~~
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/unistd.h:219:9: note: 'pipe2' has been marked as being introduced in macOS 27.0 here, but the deployment target is macOS 26.0.0
219 | int pipe2(int [2], int);
| ^
../src/util/tokenpipe.cpp:89:9: note: enclose 'pipe2' in a __builtin_available check to silence this warning
89 | if (pipe2(fds, O_CLOEXEC) != 0) {
| ^~~~~
90 | return std::nullopt;
91 | }
```
and this will need to be backported. When macOS 27 is released, we could change approach, but wanted to PR something straightforward (and backportable) for `32.x`.
ACKs for top commit:
hebasto:
ACK 9c7748315d3124d1abe6a4606743cd9274beee66, tested on macOS Tahoe 26.6.2 with CLT 27.0:
willcl-ark:
ACK 9c7748315d3124d1abe6a4606743cd9274beee66
Tree-SHA512: 5aa97b93e7038344a5118eef2660b101e443eff52ab94fb4b8eb88ec4e09b8a3000b9b4e2aa59b406d8acbb6d9add8f0c3a2dd5e1db53b1dfc97a0fcbaf48995
What changed, and why it matters
This is a build-system fix for Bitcoin Core on macOS. Apple's upcoming developer tools report that a function called `pipe2` is available, but older macOS versions do not actually provide it at runtime, which would cause Bitcoin Core to crash when run on those systems. The change simply skips the `pipe2` feature check on macOS so the project falls back to the older, widely supported `pipe` function. It is a reliability/stability fix, not a security vulnerability patch.
Treat as a normal build/compat fix. Backport to the 32.x branch as the author intended. No special security response is needed; users building on macOS with Xcode/CLT 27 on older deployment targets will avoid runtime crashes.
Security signals we found
No security-relevant code change: only build-system feature detection logic
No memory safety, cryptography, network, or consensus code touched
Crash-on-launch on older macOS is a denial-of-service-like symptom, but caused by toolchain/SDK availability mismatch, not by an attacker
No CVE, advisory, or vendor security disclosure referenced in commit
Evidence from the diff
The commit modifies cmake/introspection.cmake to skip the check_cxx_symbol_exists(pipe2 ...) introspection test when the target system is Darwin (macOS). On macOS, Xcode 27 / Command Line Tools 27 expose pipe2 in headers even though the deployment target may be older than macOS 27, causing compile-time detection to succeed and runtime binaries to call a missing symbol on older systems. The project already has a fallback to pipe in src/util/tokenpipe.cpp, so the only effect is to ensure the fallback is selected on macOS. No code behavior changes on other platforms.
Changed components
cmake/introspection.cmakesrc/util/tokenpipe.cpp (indirectly, via HAVE_DECL_PIPE2 macro)Inspect captured patch +3 / −1
### cmake/introspection.cmake
@@ -8,7 +8,9 @@ include(CheckCXXSymbolExists)
check_cxx_symbol_exists(O_CLOEXEC "fcntl.h" HAVE_O_CLOEXEC)
check_cxx_symbol_exists(fdatasync "unistd.h" HAVE_FDATASYNC)
check_cxx_symbol_exists(fork "unistd.h" HAVE_DECL_FORK)
-check_cxx_symbol_exists(pipe2 "unistd.h" HAVE_DECL_PIPE2)
+if (NOT CMAKE_SYSTEM_NAME STREQUAL "Darwin")
+ check_cxx_symbol_exists(pipe2 "unistd.h" HAVE_DECL_PIPE2)
+endif()
check_cxx_symbol_exists(setsid "unistd.h" HAVE_DECL_SETSID)
if(NOT WIN32)Why this scored 33/100
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