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/*
* failsafe.c
*
* Copyright (C) 1998, <okir@monad.swb.de>
*
* Implements fail-safe mode for nfsd/mountd.
*/
#include "system.h"
#include "logging.h"
#include "signals.h"
#include <sys/wait.h>
static const char * get_signame(int signo);
void
failsafe(int level, int ncopies)
{
int *servers, running, child, i;
int pid, signo, status;
time_t last_restart = 0, now;
int restarts = 0, backoff = 60;
servers = (int *) xmalloc(ncopies * sizeof(int));
memset(servers, 0, ncopies * sizeof(int));
/* Loop forever, until we get SIGTERM */
running = 0;
while (1) {
while (running < ncopies) {
if ((now = time(NULL)) == last_restart) {
if (++restarts > 2 * ncopies) {
Dprintf(L_ERROR,
"Servers restarting too "
"quickly, backing off.");
if (backoff < 60 * 60)
backoff <<= 1;
sleep(backoff);
}
} else {
last_restart = now;
restarts = 0;
backoff = 60;
}
/* Locate a free pid slot */
for (i = 0, child = -1; i < ncopies; i++) {
if (servers[i] == 0) {
child = i;
break;
}
}
if (child < 0)
Dprintf(L_FATAL, "failsafe: no pid slot?!");
Dprintf(D_GENERAL,
"starting server thread %d...\n", child + 1);
pid = fork();
if (pid < 0)
Dprintf(L_FATAL,
"Unable to fork for failsafe: %s",
strerror(errno));
if (pid == 0) {
/* Child process: continue with execution. */
return;
}
servers[child] = pid;
running++;
}
/* Ignore some signals */
ignore_signal(SIGTERM);
ignore_signal(SIGHUP);
ignore_signal(SIGINT);
ignore_signal(SIGCHLD);
if ((pid = wait(&status)) < 0) {
Dprintf((errno == ECHILD)? L_FATAL : L_WARNING,
"failsafe: wait(): %s", strerror(errno));
continue;
}
/* Locate the child */
for (i = 0, child = -1; i < ncopies; i++) {
if (servers[i] == pid) {
child = i;
break;
}
}
if (child < 0) {
Dprintf(L_WARNING,
"failsafe: unknown child (pid %d) terminated",
pid);
continue;
}
/* Book-keeping */
servers[child] = 0;
running--;
if (WIFSIGNALED(status)) {
signo = WTERMSIG(status);
if (signo == SIGTERM) {
Dprintf(L_NOTICE, "failsafe: "
"child %d terminated by SIGTERM. %s.",
pid, running? "Continue" : "Exit");
} else {
Dprintf(L_WARNING, "failsafe: "
"child %d terminated by %s. "
"Restarting.",
pid, get_signame(signo));
child = -1; /* Restart */
}
} else if (WIFEXITED(status)) {
Dprintf(L_NOTICE, "failsafe: "
"child %d exited, status %d.",
pid, WEXITSTATUS(status));
} else {
Dprintf(L_ERROR, "failsafe: "
"abnormal child termination, "
"pid=%d status=%d. Restarting.",
pid, status);
child = -1; /* Restart */
}
/* If child >= 0, we should not restart */
if (child >= 0) {
if (!running) {
Dprintf(D_GENERAL,
"No more children, exiting.");
exit(0);
}
for (i = child; i < ncopies-1; i++)
servers[i] = servers[i+1];
ncopies--; /* Make sure we start no new servers */
}
}
}
/*
* Failsafe session, catch core file.
*
* Not yet implemented.
* General outline: we need to fork first, because nfsd changes
* uids frequently, and the kernel won't write out a core file after
* that. The forked proc starts out with a clean dumpable flag though.
*
* After the fork, we might want to make sure we end up in some common
* directory that the failsafe loop knows about.
*/
void
failsafe_loop(int level, void (*function)(void))
{
/* NOP */
}
static const char *
get_signame(int signo)
{
static char namebuf[30];
switch (signo) {
case SIGHUP: return "SIGHUP";
case SIGINT: return "SIGINT";
case SIGQUIT: return "SIGQUIT";
case SIGILL: return "SIGILL";
case SIGTRAP: return "SIGTRAP";
case SIGIOT: return "SIGIOT";
case SIGBUS: return "SIGBUS";
case SIGFPE: return "SIGFPE";
case SIGKILL: return "SIGKILL";
case SIGUSR1: return "SIGUSR1";
case SIGSEGV: return "SIGSEGV";
case SIGUSR2: return "SIGUSR2";
case SIGPIPE: return "SIGPIPE";
case SIGALRM: return "SIGALRM";
case SIGTERM: return "SIGTERM";
case SIGCHLD: return "SIGCHLD";
case SIGCONT: return "SIGCONT";
case SIGSTOP: return "SIGSTOP";
case SIGTSTP: return "SIGTSTP";
case SIGTTIN: return "SIGTTIN";
case SIGTTOU: return "SIGTTOU";
case SIGURG: return "SIGURG";
case SIGXCPU: return "SIGXCPU";
case SIGXFSZ: return "SIGXFSZ";
case SIGVTALRM: return "SIGVTALRM";
case SIGPROF: return "SIGPROF";
case SIGWINCH: return "SIGWINCH";
case SIGIO: return "SIGIO";
case SIGPWR: return "SIGPWR";
}
sprintf(namebuf, "signal #%d", signo);
return namebuf;
}
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