From fa8740b675b0da1fa67370ccf042a78ae802b227 Mon Sep 17 00:00:00 2001 From: Simon Marchi Date: Mon, 5 Jul 2021 09:56:10 -0400 Subject: [PATCH] gdb: fall back on sigpending + sigwait if sigtimedwait is not available The macOS platform does not provide sigtimedwait, so we get: CXX compile/compile.o In file included from /Users/smarchi/src/binutils-gdb/gdb/compile/compile.c:46: /Users/smarchi/src/binutils-gdb/gdb/../gdbsupport/scoped_ignore_signal.h:69:4: error: use of undeclared identifier 'sigtimedwait' sigtimedwait (&set, nullptr, &zero_timeout); ^ An alternative to sigtimedwait with a timeout of 0 is to use sigpending, to first check which signals are pending, and then sigwait, to consume them. Since that's slightly more expensive (2 syscalls instead of 1), keep using sigtimedwait for the platforms that provide it, and fall back to sigpending + sigwait for the others. gdbsupport/ChangeLog: * scoped_ignore_signal.h (struct scoped_ignore_signal) <~scoped_ignore_signal>: Use sigtimedwait if HAVE_SIGTIMEDWAIT is defined, else use sigpending + sigwait. Change-Id: I2a72798337e81dd1bbd21214736a139dd350af87 Co-Authored-By: John Baldwin --- gdbsupport/ChangeLog | 6 ++++++ gdbsupport/scoped_ignore_signal.h | 15 +++++++++++++-- 2 files changed, 19 insertions(+), 2 deletions(-) diff --git a/gdbsupport/ChangeLog b/gdbsupport/ChangeLog index afe9171ff75..bb54ff82f86 100644 --- a/gdbsupport/ChangeLog +++ b/gdbsupport/ChangeLog @@ -1,3 +1,9 @@ +2021-07-05 Simon Marchi + + * scoped_ignore_signal.h (struct scoped_ignore_signal) + <~scoped_ignore_signal>: Use sigtimedwait if HAVE_SIGTIMEDWAIT + is defined, else use sigpending + sigwait. + 2021-07-05 Simon Marchi * common.m4 (GDB_AC_COMMON): Check for sigtimedwait. diff --git a/gdbsupport/scoped_ignore_signal.h b/gdbsupport/scoped_ignore_signal.h index a14c96779bf..57dd4b6d402 100644 --- a/gdbsupport/scoped_ignore_signal.h +++ b/gdbsupport/scoped_ignore_signal.h @@ -58,7 +58,6 @@ public: if (!m_was_blocked) { sigset_t set; - const timespec zero_timeout = {}; sigemptyset (&set); sigaddset (&set, Sig); @@ -66,7 +65,19 @@ public: /* If we got a pending Sig signal, consume it before unblocking. */ if (ConsumePending) - sigtimedwait (&set, nullptr, &zero_timeout); + { +#ifdef HAVE_SIGTIMEDWAIT + const timespec zero_timeout = {}; + + sigtimedwait (&set, nullptr, &zero_timeout); +#else + sigset_t pending; + + sigpending (&pending); + if (sigismember (&pending, Sig)) + sigwait (&set, nullptr); +#endif + } sigprocmask (SIG_UNBLOCK, &set, nullptr); } -- 2.47.3