This commit is the result of running the gdb/copyright.py script,
which automated the update of the copyright year range for all
source files managed by the GDB project to be updated to include
year 2023.
I tried building GDB on GNU/Hurd, and ran into this warning:
gdbsupport/scoped_ignore_signal.h:78:16: error: null argument where non-null required (argument 2) [-Werror=nonnull]
This is because in this commit:
commit 99624310dd82542c389c89c2e55d8cae36bb74e1
Date: Sun Jun 27 15:13:14 2021 -0400
gdb: fall back on sigpending + sigwait if sigtimedwait is not available
A call to sigwait was introduced that passes nullptr as the second
argument, this call is only reached if sigtimedwait is not supported.
The original patch was written for macOS, I assume on that target
passing nullptr as the second argument is fine.
On my GNU/Linux box, the man-page for sigwait doesn't mention that
nullptr is allowed for the second argument, so my assumption would be
that nullptr is not OK, and, if I change the '#ifdef
HAVE_SIGTIMEDWAIT' introduced by the above patch to '#if 0', and
rebuild on GNU/Linux, I see the same warning that I see on GNU/Hurd.
I propose that we stop passing nullptr as the second argument to
sigwait, and instead pass a valid int pointer. The value returned in
the int can then be used in an assert.
For testing, I (locally) made the change to the #ifdef I mentioned
above, compiled GDB, and ran the usual tests, this meant I was using
sigwait instead on sigtimedwait on GNU/Linux, I saw no regressions.
This commit brings all the changes made by running gdb/copyright.py
as per GDB's Start of New Year Procedure.
For the avoidance of doubt, all changes in this commits were
performed by the script.
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 <jhb@FreeBSD.org>
Because SIGTTOU is sent to the whole process instead of to a specific
thread, consuming a pending SIGTTOU in the destructor of
scoped_ignore_sigttou could consume a SIGTTOU signal raised due to
actions done by some other thread. Simply avoid sigtimedwait in
scoped_ignore_sigttou, thus plugging the race. This works because we
know that when the thread writes to the terminal and the signal is
blocked, the kernel does not raise the signal at all.
Tested on GNU/Linux, Solaris 11 and FreeBSD.
gdb/ChangeLog:
yyyy-mm-dd Pedro Alves <pedro@palves.net>
* scoped_ignore_signal.h (scoped_ignore_signal): Add
ConsumePending template parameter.
(scoped_ignore_signal::~scoped_ignore_signal): Skip calling
sigtimedwait if ConsumePending is false.
(scoped_ignore_sigpipe): Initialize with ConsumePending=true.
* scoped_ignore_sigttou.h (scoped_ignore_sigttou)
<m_ignore_signal>: Initialize with ConsumePending=false.
Change-Id: I92f754dbc45c45819dce2ce68b8c067d8d5c61b1
The problem with using signal(...) to temporarily ignore a signal, is
that that changes the the signal disposition for the whole process.
If multiple threads do it at the same time, you have a race.
Fix this by using sigprocmask + sigtimedwait to implement the ignoring
instead, if available, which I think probably means everywhere except
Windows nowadays. This way, we only change the signal mask for the
current thread, so there's no race.
Change-Id: Idfe3fb08327ef8cae926f3de9ee81c56a83b1738
gdbsupport/ChangeLog:
yyyy-mm-dd Pedro Alves <pedro@palves.net>
* scoped_ignore_signal.h
(scoped_ignore_signal::scoped_ignore_signal)
[HAVE_SIGPROCMASK]: Use sigprocmask to block the signal instead of
changing the signal disposition for the whole process.
(scoped_ignore_signal::~scoped_ignore_signal) [HAVE_SIGPROCMASK]:
Use sigtimedwait and sigprocmask to flush and unblock the signal.
We currently have scoped_restore_sigttou and scoped_restore_sigpipe
doing basically the same thing -- temporarily ignoring a specific
signal.
This patch introduce a scoped_restore_signal type that can be used for
both. This will become more important for the next patch which
changes how the signal-ignoring is implemented.
scoped_restore_sigpipe is a straight alias to
scoped_restore_signal<SIGPIPE> on systems that define SIGPIPE, and an
alias to scoped_restore_signal_nop (a no-op version of
scoped_restore_signal) otherwise.
scoped_restore_sigttou is not a straight alias because it wants to
check the job_control global.
gdb/ChangeLog:
yyyy-mm-dd Pedro Alves <pedro@palves.net>
* gdbsupport/scoped_ignore_signal.h: New.
* compile/compile.c: Include gdbsupport/scoped_ignore_signal.h
instead of <signal.h>. Don't include <unistd.h>.
(scoped_ignore_sigpipe): Remove.
* gdbsupport/scoped_ignore_sigttou.h: Include gdbsupport/scoped_ignore_signal.h
instead of <signal.h>. Don't include <unistd.h>.
(lazy_init): New.
(scoped_ignore_sigttou): Reimplement using scoped_ignore_signal
and lazy_init.
Change-Id: Ibb44d0bd705e96df03ef0787c77358a4a7b7086c
