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* LVM2/daemons/common daemon-server.h daemon-ser ...
@ 2011-05-13 8:45 mornfall
0 siblings, 0 replies; only message in thread
From: mornfall @ 2011-05-13 8:45 UTC (permalink / raw)
To: lvm-devel, lvm2-cvs
CVSROOT: /cvs/lvm2
Module name: LVM2
Changes by: mornfall@sourceware.org 2011-05-13 08:45:47
Modified files:
daemons/common : daemon-server.h
Added files:
daemons/common : daemon-server.c
Log message:
Start filling in some of the common daemon (server-side) functionality, taking
dmeventd code as a starting point.
Patches:
http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/daemons/common/daemon-server.c.diff?cvsroot=lvm2&r1=NONE&r2=1.1
http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/daemons/common/daemon-server.h.diff?cvsroot=lvm2&r1=1.1&r2=1.2
/cvs/lvm2/LVM2/daemons/common/daemon-server.c,v --> standard output
revision 1.1
--- LVM2/daemons/common/daemon-server.c
+++ - 2011-05-13 08:45:47.525615000 +0000
@@ -0,0 +1,204 @@
+/*
+ * Copyright (C) 2011 Red Hat, Inc. All rights reserved.
+ *
+ * This copyrighted material is made available to anyone wishing to use,
+ * modify, copy, or redistribute it subject to the terms and conditions
+ * of the GNU Lesser General Public License v.2.1.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <dlfcn.h>
+#include <errno.h>
+#include <pthread.h>
+#include <sys/file.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <sys/time.h>
+#include <sys/resource.h>
+#include <unistd.h>
+#include <signal.h>
+
+#include <syslog.h>
+
+/* Create a device monitoring thread. */
+static int _pthread_create(pthread_t *t, void *(*fun)(void *), void *arg, int stacksize)
+{
+ pthread_attr_t attr;
+ pthread_attr_init(&attr);
+ /*
+ * We use a smaller stack since it gets preallocated in its entirety
+ */
+ pthread_attr_setstacksize(&attr, stacksize);
+ return pthread_create(t, &attr, fun, arg);
+}
+
+static volatile sig_atomic_t _shutdown_requested = 0;
+
+static void _exit_handler(int sig __attribute__((unused)))
+{
+ _shutdown_requested = 1;
+}
+
+#ifdef linux
+# define OOM_ADJ_FILE "/proc/self/oom_adj"
+
+/* From linux/oom.h */
+# define OOM_DISABLE (-17)
+# define OOM_ADJUST_MIN (-16)
+
+/*
+ * Protection against OOM killer if kernel supports it
+ */
+static int _set_oom_adj(int val)
+{
+ FILE *fp;
+
+ struct stat st;
+
+ if (stat(OOM_ADJ_FILE, &st) == -1) {
+ if (errno == ENOENT)
+ perror(OOM_ADJ_FILE " not found");
+ else
+ perror(OOM_ADJ_FILE ": stat failed");
+ return 1;
+ }
+
+ if (!(fp = fopen(OOM_ADJ_FILE, "w"))) {
+ perror(OOM_ADJ_FILE ": fopen failed");
+ return 0;
+ }
+
+ fprintf(fp, "%i", val);
+ if (dm_fclose(fp))
+ perror(OOM_ADJ_FILE ": fclose failed");
+
+ return 1;
+}
+#endif
+
+static void remove_lockfile(const char *file)
+{
+ if (unlink(file))
+ perror(file ": unlink failed");
+}
+
+static void _daemonise(void)
+{
+ int child_status;
+ int fd;
+ pid_t pid;
+ struct rlimit rlim;
+ struct timeval tval;
+ sigset_t my_sigset;
+
+ sigemptyset(&my_sigset);
+ if (sigprocmask(SIG_SETMASK, &my_sigset, NULL) < 0) {
+ fprintf(stderr, "Unable to restore signals.\n");
+ exit(EXIT_FAILURE);
+ }
+ signal(SIGTERM, &_exit_handler);
+
+ switch (pid = fork()) {
+ case -1:
+ perror("fork failed:");
+ exit(EXIT_FAILURE);
+
+ case 0: /* Child */
+ break;
+
+ default:
+ /* Wait for response from child */
+ while (!waitpid(pid, &child_status, WNOHANG) && !_exit_now) {
+ tval.tv_sec = 0;
+ tval.tv_usec = 250000; /* .25 sec */
+ select(0, NULL, NULL, NULL, &tval);
+ }
+
+ if (_shutdown_requested) /* Child has signaled it is ok - we can exit now */
+ exit(0);
+
+ /* Problem with child. Determine what it is by exit code */
+ switch (WEXITSTATUS(child_status)) {
+ case EXIT_DESC_CLOSE_FAILURE:
+ case EXIT_DESC_OPEN_FAILURE:
+ case EXIT_FIFO_FAILURE:
+ case EXIT_CHDIR_FAILURE:
+ default:
+ fprintf(stderr, "Child exited with code %d\n", WEXITSTATUS(child_status));
+ break;
+ }
+
+ exit(WEXITSTATUS(child_status));
+ }
+
+ if (chdir("/"))
+ exit(1);
+
+ if (getrlimit(RLIMIT_NOFILE, &rlim) < 0)
+ fd = 256; /* just have to guess */
+ else
+ fd = rlim.rlim_cur;
+
+ for (--fd; fd >= 0; fd--)
+ close(fd);
+
+ if ((open("/dev/null", O_RDONLY) < 0) ||
+ (open("/dev/null", O_WRONLY) < 0) ||
+ (open("/dev/null", O_WRONLY) < 0))
+ exit(1);
+
+ setsid();
+}
+
+void daemon_start(daemon_state s, handle_request r)
+{
+ /*
+ * Switch to C locale to avoid reading large locale-archive file used by
+ * some glibc (on some distributions it takes over 100MB). Some daemons
+ * need to use mlockall().
+ */
+ if (setenv("LANG", "C", 1))
+ perror("Cannot set LANG to C");
+
+ if (!s.foreground)
+ _daemonise();
+
+ /* TODO logging interface should be somewhat more elaborate */
+ openlog(s.name, LOG_PID, LOG_DAEMON);
+
+ (void) dm_prepare_selinux_context(s.pidfile, S_IFREG);
+
+ /*
+ * NB. Past this point, exit is not allowed. You have to return to this
+ * function at all costs. More or less.
+ */
+ if (dm_create_lockfile(s.pidfile) == 0)
+ exit(1);
+
+ (void) dm_prepare_selinux_context(NULL, 0);
+
+ /* Set normal exit signals to request shutdown instead of dying. */
+ signal(SIGINT, &_exit_handler);
+ signal(SIGHUP, &_exit_handler);
+ signal(SIGQUIT, &_exit_handler);
+
+#ifdef linux
+ if (s.avoid_oom && !_set_oom_adj(OOM_DISABLE) && !_set_oom_adj(OOM_ADJUST_MIN))
+ syslog(LOG_ERR, "Failed to set oom_adj to protect against OOM killer");
+#endif
+
+ /* Signal parent, letting them know we are ready to go. */
+ if (!s.foreground)
+ kill(getppid(), SIGTERM);
+
+ while (!_shutdown_requested) {
+ /* TODO: do work */
+ }
+
+ syslog(LOG_NOTICE, "%s shutting down", s.name);
+ closelog();
+ remove_lockfile(s.pidfile);
+}
--- LVM2/daemons/common/daemon-server.h 2011/05/13 08:07:28 1.1
+++ LVM2/daemons/common/daemon-server.h 2011/05/13 08:45:46 1.2
@@ -23,6 +23,19 @@
} client_handle;
typedef struct {
+ /*
+ * The maximal stack size for individual daemon threads. This is
+ * essential for daemons that need to be locked into memory, since
+ * pthread's default is 10M per thread.
+ */
+ int thread_stack_size;
+
+ /* Flags & attributes affecting the behaviour of the daemon. */
+ unsigned avoid_oom:1;
+ unsigned foreground:1;
+ const char *name;
+ const char *pidfile;
+
void *private; /* the global daemon state */
} daemon_state;
@@ -45,7 +58,8 @@
/*
* Start serving the requests. This does all the daemonisation, socket setup
- * work and so on.
+ * work and so on. This function takes over the process, and upon failure, it
+ * will terminate execution. It may be called at most once.
*/
void daemon_start(daemon_state s, handle_request r);
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2011-05-13 8:45 LVM2/daemons/common daemon-server.h daemon-ser mornfall
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