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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 21:12:04 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 21:12:04 +0000
commiteac54b7c4aec25060d7bd856f7cdc290943d6aae (patch)
tree9a6d81c9f88df4698e746d63d14ddafeddd918b8 /src/xz/signals.c
parentInitial commit. (diff)
downloadxz-utils-eac54b7c4aec25060d7bd856f7cdc290943d6aae.tar.xz
xz-utils-eac54b7c4aec25060d7bd856f7cdc290943d6aae.zip
Adding upstream version 5.4.1.upstream/5.4.1upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/xz/signals.c')
-rw-r--r--src/xz/signals.c209
1 files changed, 209 insertions, 0 deletions
diff --git a/src/xz/signals.c b/src/xz/signals.c
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+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file signals.c
+/// \brief Handling signals to abort operation
+//
+// Author: Lasse Collin
+//
+// This file has been put into the public domain.
+// You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "private.h"
+
+
+volatile sig_atomic_t user_abort = false;
+
+
+#if !(defined(_WIN32) && !defined(__CYGWIN__))
+
+/// If we were interrupted by a signal, we store the signal number so that
+/// we can raise that signal to kill the program when all cleanups have
+/// been done.
+static volatile sig_atomic_t exit_signal = 0;
+
+/// Mask of signals for which we have established a signal handler to set
+/// user_abort to true.
+static sigset_t hooked_signals;
+
+/// True once signals_init() has finished. This is used to skip blocking
+/// signals (with uninitialized hooked_signals) if signals_block() and
+/// signals_unblock() are called before signals_init() has been called.
+static bool signals_are_initialized = false;
+
+/// signals_block() and signals_unblock() can be called recursively.
+static size_t signals_block_count = 0;
+
+
+static void
+signal_handler(int sig)
+{
+ exit_signal = sig;
+ user_abort = true;
+
+#ifndef TUKLIB_DOSLIKE
+ io_write_to_user_abort_pipe();
+#endif
+
+ return;
+}
+
+
+extern void
+signals_init(void)
+{
+ // List of signals for which we establish the signal handler.
+ static const int sigs[] = {
+ SIGINT,
+ SIGTERM,
+#ifdef SIGHUP
+ SIGHUP,
+#endif
+#ifdef SIGPIPE
+ SIGPIPE,
+#endif
+#ifdef SIGXCPU
+ SIGXCPU,
+#endif
+#ifdef SIGXFSZ
+ SIGXFSZ,
+#endif
+ };
+
+ // Mask of the signals for which we have established a signal handler.
+ sigemptyset(&hooked_signals);
+ for (size_t i = 0; i < ARRAY_SIZE(sigs); ++i)
+ sigaddset(&hooked_signals, sigs[i]);
+
+#ifdef SIGALRM
+ // Add also the signals from message.c to hooked_signals.
+ for (size_t i = 0; message_progress_sigs[i] != 0; ++i)
+ sigaddset(&hooked_signals, message_progress_sigs[i]);
+#endif
+
+ // Using "my_sa" because "sa" may conflict with a sockaddr variable
+ // from system headers on Solaris.
+ struct sigaction my_sa;
+
+ // All the signals that we handle we also blocked while the signal
+ // handler runs.
+ my_sa.sa_mask = hooked_signals;
+
+ // Don't set SA_RESTART, because we want EINTR so that we can check
+ // for user_abort and cleanup before exiting. We block the signals
+ // for which we have established a handler when we don't want EINTR.
+ my_sa.sa_flags = 0;
+ my_sa.sa_handler = &signal_handler;
+
+ for (size_t i = 0; i < ARRAY_SIZE(sigs); ++i) {
+ // If the parent process has left some signals ignored,
+ // we don't unignore them.
+ struct sigaction old;
+ if (sigaction(sigs[i], NULL, &old) == 0
+ && old.sa_handler == SIG_IGN)
+ continue;
+
+ // Establish the signal handler.
+ if (sigaction(sigs[i], &my_sa, NULL))
+ message_signal_handler();
+ }
+
+ signals_are_initialized = true;
+
+ return;
+}
+
+
+#ifndef __VMS
+extern void
+signals_block(void)
+{
+ if (signals_are_initialized) {
+ if (signals_block_count++ == 0) {
+ const int saved_errno = errno;
+ mythread_sigmask(SIG_BLOCK, &hooked_signals, NULL);
+ errno = saved_errno;
+ }
+ }
+
+ return;
+}
+
+
+extern void
+signals_unblock(void)
+{
+ if (signals_are_initialized) {
+ assert(signals_block_count > 0);
+
+ if (--signals_block_count == 0) {
+ const int saved_errno = errno;
+ mythread_sigmask(SIG_UNBLOCK, &hooked_signals, NULL);
+ errno = saved_errno;
+ }
+ }
+
+ return;
+}
+#endif
+
+
+extern void
+signals_exit(void)
+{
+ const int sig = (int)exit_signal;
+
+ if (sig != 0) {
+#if defined(TUKLIB_DOSLIKE) || defined(__VMS)
+ // Don't raise(), set only exit status. This avoids
+ // printing unwanted message about SIGINT when the user
+ // presses C-c.
+ set_exit_status(E_ERROR);
+#else
+ struct sigaction sa;
+ sa.sa_handler = SIG_DFL;
+ sigfillset(&sa.sa_mask);
+ sa.sa_flags = 0;
+ sigaction(sig, &sa, NULL);
+ raise(sig);
+#endif
+ }
+
+ return;
+}
+
+#else
+
+// While Windows has some very basic signal handling functions as required
+// by C89, they are not really used, and e.g. SIGINT doesn't work exactly
+// the way it does on POSIX (Windows creates a new thread for the signal
+// handler). Instead, we use SetConsoleCtrlHandler() to catch user
+// pressing C-c, because that seems to be the recommended way to do it.
+//
+// NOTE: This doesn't work under MSYS. Trying with SIGINT doesn't work
+// either even if it appeared to work at first. So test using Windows
+// console window.
+
+static BOOL WINAPI
+signal_handler(DWORD type lzma_attribute((__unused__)))
+{
+ // Since we don't get a signal number which we could raise() at
+ // signals_exit() like on POSIX, just set the exit status to
+ // indicate an error, so that we cannot return with zero exit status.
+ set_exit_status(E_ERROR);
+ user_abort = true;
+ return TRUE;
+}
+
+
+extern void
+signals_init(void)
+{
+ if (!SetConsoleCtrlHandler(&signal_handler, TRUE))
+ message_signal_handler();
+
+ return;
+}
+
+#endif