/*
- * Copyright (C) 2004-2010 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2004 Andre Noll <maan@tuebingen.mpg.de>
*
* Licensed under the GPL v2. For licencing details see COPYING.
*/
#include <signal.h>
#include <sys/types.h>
-#include <dirent.h>
+#include <regex.h>
#include "para.h"
#include "error.h"
#include "fd.h"
+#include "list.h"
+#include "string.h"
+#include "sched.h"
+#include "signal.h"
static int signal_pipe[2];
* during the application's startup part, followed by subsequent calls
* to para_install_sighandler() for each signal that should be caught.
*
- * para_signal_init() installs a generic signal handler which is used for all
- * signals simultaneously. When a signal arrives, this generic signal handler
- * writes the corresponding signal number to the signal pipe so that the
- * application can test for pending signals simply by checking the signal pipe
- * for reading, e.g. by using the select(2) system call.
+ * A generic signal handler is used for all signals simultaneously. When a
+ * signal arrives, the signal handler writes the number of the signal received
+ * to one end of the signal pipe. The application can test for pending signals
+ * by checking if the file descriptor of the other end of the signal pipe is
+ * ready for reading, see select(2).
*
- * \return This function either succeeds or calls exit(2) to terminate
- * the current process. On success, the file descriptor of the signal pipe is
- * returned.
+ * \return This function either succeeds or calls exit(2) to terminate the
+ * current process. On success, a signal task structure is returned.
*/
-int para_signal_init(void)
+struct signal_task *signal_init_or_die(void)
{
+ struct signal_task *st;
int ret;
+
+ PARA_NOTICE_LOG("setting up signal handling\n");
if (pipe(signal_pipe) < 0) {
ret = -ERRNO_TO_PARA_ERROR(errno);
goto err_out;
ret = mark_fd_nonblocking(signal_pipe[1]);
if (ret < 0)
goto err_out;
- return signal_pipe[0];
+ st = para_calloc(sizeof(*st));
+ st->fd = signal_pipe[0];
+ return st;
err_out:
PARA_EMERG_LOG("%s\n", para_strerror(-ret));
exit(EXIT_FAILURE);
}
-/*
- * just write one integer to signal pipe
- */
+/* Write the signal number to signal pipe. */
static void generic_signal_handler(int s)
{
+ /*
+ * Signal handlers that make system calls must save a copy of errno on
+ * entry to the handler and restore it on exit, to prevent the
+ * possibility of overwriting a errno value that had previously been
+ * set in the main program.
+ */
+ int save_errno = errno;
ssize_t ret = write(signal_pipe[1], &s, sizeof(int));
- if (ret == sizeof(int))
+ if (ret == sizeof(int)) {
+ errno = save_errno;
return;
+ }
if (ret < 0)
PARA_EMERG_LOG("%s\n", strerror(errno));
else
para_sigaction(sig, &generic_signal_handler);
}
+/**
+ * Block a signal for the caller.
+ *
+ * \param sig The signal to block.
+ *
+ * This sets the given signal in the current signal mask of the calling process
+ * to prevent this signal from delivery.
+ *
+ * \sa \ref para_unblock_signal(), sigprocmask(2), sigaddset(3).
+ */
+void para_block_signal(int sig)
+{
+ sigset_t set;
+
+ PARA_DEBUG_LOG("blocking signal %d\n", sig);
+ sigemptyset(&set);
+ sigaddset(&set, sig);
+ sigprocmask(SIG_BLOCK, &set, NULL);
+}
+
+/**
+ * Unblock a signal.
+ *
+ * \param sig The signal to unblock.
+ *
+ * This function removes the given signal from the current set of blocked
+ * signals.
+ *
+ * \sa \ref para_block_signal(), sigprocmask(2), sigaddset(3).
+ */
+void para_unblock_signal(int sig)
+{
+ sigset_t set;
+
+ PARA_DEBUG_LOG("unblocking signal %d\n", sig);
+ sigemptyset(&set);
+ sigaddset(&set, sig);
+ sigprocmask(SIG_UNBLOCK, &set, NULL);
+}
+
/**
* Return the number of the next pending signal.
*
- * This should be called if the fd for the signal pipe is ready for reading.
+ * \param rfds The fd_set containing the signal pipe.
*
- * \return On success, the number of the received signal is returned. If the
- * read returned zero or was interrupted by another signal the function returns
- * 0. Otherwise, a negative error value is returned.
+ * \return On success, the number of the received signal is returned. If there
+ * is no signal currently pending, the function returns zero. On read errors
+ * from the signal pipe, the process is terminated.
*/
-int para_next_signal(void)
+int para_next_signal(fd_set *rfds)
{
- int s;
- ssize_t r = read(signal_pipe[0], &s, sizeof(s));
+ size_t n;
+ int s, ret = read_nonblock(signal_pipe[0], &s, sizeof(s), rfds, &n);
- if (!r) {
- PARA_CRIT_LOG("read from signal pipe returned zero\n");
- return 0;
- }
- if (r < 0) {
- if (errno == EAGAIN || errno == EINTR)
- return 0;
- return -ERRNO_TO_PARA_ERROR(errno);
+ if (ret < 0) {
+ PARA_EMERG_LOG("%s\n", para_strerror(-ret));
+ exit(EXIT_FAILURE);
}
- assert(r == sizeof(s));
+ if (n == 0)
+ return 0;
+ assert(n == sizeof(s));
PARA_DEBUG_LOG("next signal: %d\n", s);
return s;
}
/**
- * Close the write end of the signal pipe.
+ * Close the write end of the signal pipe, deallocate resources.
+ *
+ * \param st The pointer obtained earlier from signal_init_or_die().
*/
-void para_signal_shutdown(void)
+void signal_shutdown(struct signal_task *st)
{
close(signal_pipe[1]);
+ free(st);
}
projects / paraslash.git / blobdiff