Fd leaks and cloexec#508
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gh-worker-dd-mergequeue-cf854d[bot] merged 3 commits intoMar 11, 2026
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In library mode, ddprof_start_profiling() fork+execs the daemon. Every FD without CLOEXEC in the parent leaks into the child process. Changes: - create_elf.cc: use UniqueFd for RAII cleanup (fixes FD leak on error paths), add O_CLOEXEC, fix "prox" typo in log message - ringbuffer_utils.cc: close mapfd on ftruncate/eventfd error paths, add EFD_CLOEXEC to eventfd() - ipc.cc: use accept4() with SOCK_CLOEXEC (parent socket already uses SOCK_CLOEXEC but accepted connections didn't inherit it), add SFD_CLOEXEC to signalfd() - daemonize.cc: add O_CLOEXEC to pipe2() - ddprof_module_lib.cc: add O_CLOEXEC to open() calls (already uses UniqueFd for RAII) Fixes #497
The write end is passed to ddprof via --pipefd and must survive the execve() in exec_ddprof() so ddprof can write back the socket path. Setting O_CLOEXEC caused it to be closed on exec, breaking profiler startup in library mode.
r1viollet
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Mar 6, 2026
| const int exe_fd = ::open("/proc/self/exe", O_RDONLY); | ||
| if (exe_fd == -1) { | ||
| LG_WRN("Failed to open /prox/self/exe"); | ||
| const UniqueFd exe_fd{::open("/proc/self/exe", O_RDONLY | O_CLOEXEC)}; |
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cloexec is probably useless here
nsavoire
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Mar 6, 2026
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These fixes improve correctness and are good defensive hygiene. However, they are unlikely to resolve FD accumulation in long-running services using library mode: the CLOEXEC additions are all in ddprof's own process (the daemon), not in the target process or the injected library. FDs in the target process that would leak into a restarted ddprof daemon across fork+exec cycles would need to be investigated on the library side (dd_profiling.cc).