/*
- * Copyright (c) 2008, 2009 Nicira Networks.
+ * Copyright (c) 2008, 2009, 2010 Nicira Networks.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
/* Hooks to call upon catching a signal */
struct hook {
- void (*func)(void *aux);
+ void (*hook_cb)(void *aux);
+ void (*cancel_cb)(void *aux);
void *aux;
bool run_at_exit;
};
static int signal_fds[2];
static volatile sig_atomic_t stored_sig_nr = SIG_ATOMIC_MAX;
-/* Disabled by fatal_signal_fork()? */
-static bool disabled;
-
static void fatal_signal_init(void);
static void atexit_handler(void);
static void call_hooks(int sig_nr);
}
}
-/* Registers 'hook' to be called when a process termination signal is raised.
- * If 'run_at_exit' is true, 'hook' is also called during normal process
- * termination, e.g. when exit() is called or when main() returns.
+/* Registers 'hook_cb' to be called when a process termination signal is
+ * raised. If 'run_at_exit' is true, 'hook_cb' is also called during normal
+ * process termination, e.g. when exit() is called or when main() returns.
*
- * The hook is not called immediately from the signal handler but rather the
+ * 'hook_cb' is not called immediately from the signal handler but rather the
* next time the poll loop iterates, so it is freed from the usual restrictions
- * on signal handler functions. */
+ * on signal handler functions.
+ *
+ * If the current process forks, fatal_signal_fork() may be called to clear the
+ * parent process's fatal signal hooks, so that 'hook_cb' is only called when
+ * the child terminates, not when the parent does. When fatal_signal_fork() is
+ * called, it calls the 'cancel_cb' function if it is nonnull, passing 'aux',
+ * to notify that the hook has been canceled. This allows the hook to free
+ * memory, etc. */
void
-fatal_signal_add_hook(void (*func)(void *aux), void *aux, bool run_at_exit)
+fatal_signal_add_hook(void (*hook_cb)(void *aux), void (*cancel_cb)(void *aux),
+ void *aux, bool run_at_exit)
{
fatal_signal_init();
+
assert(n_hooks < MAX_HOOKS);
- hooks[n_hooks].func = func;
+ hooks[n_hooks].hook_cb = hook_cb;
+ hooks[n_hooks].cancel_cb = cancel_cb;
hooks[n_hooks].aux = aux;
hooks[n_hooks].run_at_exit = run_at_exit;
n_hooks++;
static void
atexit_handler(void)
{
- if (!disabled) {
- call_hooks(0);
- }
+ call_hooks(0);
}
static void
for (i = 0; i < n_hooks; i++) {
struct hook *h = &hooks[i];
if (sig_nr || h->run_at_exit) {
- h->func(h->aux);
+ h->hook_cb(h->aux);
}
}
}
}
\f
+/* Files to delete on exit. (The 'data' member of each node is unused.) */
static struct shash files = SHASH_INITIALIZER(&files);
+/* Has a hook function been registered with fatal_signal_add_hook() (and not
+ * cleared by fatal_signal_fork())? */
+static bool added_hook;
+
static void unlink_files(void *aux);
+static void cancel_files(void *aux);
static void do_unlink_files(void);
/* Registers 'file' to be unlinked when the program terminates via exit() or a
void
fatal_signal_add_file_to_unlink(const char *file)
{
- static bool added_hook = false;
if (!added_hook) {
added_hook = true;
- fatal_signal_add_hook(unlink_files, NULL, true);
+ fatal_signal_add_hook(unlink_files, cancel_files, NULL, true);
}
if (!shash_find(&files, file)) {
do_unlink_files();
}
+static void
+cancel_files(void *aux UNUSED)
+{
+ shash_clear(&files);
+ added_hook = false;
+}
+
static void
do_unlink_files(void)
{
}
}
\f
-/* Disables the fatal signal hook mechanism. Following a fork, one of the
- * resulting processes can call this function to allow it to terminate without
- * triggering fatal signal processing or removing files. Fatal signal
- * processing is still enabled in the other process. */
+/* Clears all of the fatal signal hooks without executing them. If any of the
+ * hooks passed a 'cancel_cb' function to fatal_signal_add_hook(), then those
+ * functions will be called, allowing them to free resources, etc.
+ *
+ * Following a fork, one of the resulting processes can call this function to
+ * allow it to terminate without calling the hooks registered before calling
+ * this function. New hooks registered after calling this function will take
+ * effect normally. */
void
fatal_signal_fork(void)
{
size_t i;
- disabled = true;
-
- for (i = 0; i < ARRAY_SIZE(fatal_signals); i++) {
- int sig_nr = fatal_signals[i];
- if (signal(sig_nr, SIG_DFL) == SIG_IGN) {
- signal(sig_nr, SIG_IGN);
+ for (i = 0; i < n_hooks; i++) {
+ struct hook *h = &hooks[i];
+ if (h->cancel_cb) {
+ h->cancel_cb(h->aux);
}
}
+ n_hooks = 0;
/* Raise any signals that we have already received with the default
* handler. */
projects / openvswitch / commitdiff