* speedy, the specified number of servers is started
* right away.) The default is 4.
*
+ * -c<interval>
+ * Stale server check interval, in seconds. The worker
+ * process group will get a SIGTERM when it is no longer
+ * needed to process new requests. Ideally it would continue
+ * to serve any existing requests. The SIGTERM will arrive no
+ * earlier than <interval> after the last request arrived at
+ * the containing webserver. Default is 300.
+ *
* -D
* Debug mode. Do not actually run program. Instead, print
* out what we would do.
* ~/.cgi-fcgi-interp/<node>/
* and inside there uses these paths
* s<ident>
- * g<inum>
+ * l<ident> used to lock around garbage collection
*
* If -M<ident> is not specified then an initial substricg of the
* lowercase hex of the sha256 of the <script> (ie, our argv[1]) is
* - check for and maybe create <base>
* - stat and lstat the <script>
* - stat the socket and check its timestamp
- * if it is too old, rename it to g<inum>.<pid> (where
- * <inum> and <pid> are in decimal)
- * and run garbage collection
- * - run cgi-fcgi -connect SOCKET SCRIPT
+ * if it is too old, unlink it
+ * - dup stderr, mark no cloexec
+ * - run cgi-fcgi -connect SOCKET \
+ * cgi-fcgi-interp \
+ * --stage2 <was-stderr> <socket> \
+ -c<check-interval> \
+ * \
+ * <interp> <script>
+ *
+ * --stage2 does this:
+ * - dup2 <was-stderr> to fd 2
+ * - open /dev/null and expect fd 1 (and if not, close it)
+ * - become a new process group
+ * - lstat <socket> to find its inum, mtime
+ * - fork/exec <interp> <script>
+ * - periodically lstat <interp> and <script> and
+ * if mtime is newer than our start time
+ * kill process group (at second iteration)
*/
#include "common.h"
#include <sys/utsname.h>
#include <sys/socket.h>
#include <sys/un.h>
+#include <sys/file.h>
#include <unistd.h>
+#include <fcntl.h>
#include <pwd.h>
#include <err.h>
-
+#include <time.h>
+#include <signal.h>
+#include <sys/wait.h>
+
#include <nettle/sha.h>
#include "myopt.h"
#define MINHEXHASH 33
static const char *interp, *ident;
-static int numservers, debugmode;
+static int numservers=4, debugmode, stage2;
+static int check_interval=300;
void diee(const char *m) {
err(127, "error: %s failed", m);
{ 0, 'g', 1, .sassignto= &ident },
{ 0, 'M', 1, .call=of_iassign, .iassignto= &numservers },
{ 0, 'D', 0, .iassignto= &debugmode, .arg= 1 },
+ { 0, 'c', 1, .call=of_iassign, .iassignto= &check_interval },
+ { "--stage2",0, 0, .iassignto= &stage2, .arg= 1 },
{ 0 }
};
static uid_t us;
static const char *run_base, *script, *socket_path;
+static int stderr_copy;
static bool find_run_base_var_run(void) {
struct stat stab;
((tvp)->tv_sec cmp (uvp)->tv_sec))
#endif /*timespeccmp*/
+
+
static bool stab_isnewer(const struct stat *a, const struct stat *b) {
- return 0;
+#ifdef st_mtime
+ return timespeccmp(&a->st_mtim, &b->st_mtim, >);
+#else
+ return a->st_mtime > &b->st_mtime;
+#endif
}
-static bool check_garbage(void) {
- struct stat sock_stab, script_stab;
+static bool check_garbage_vs(const struct stat *started) {
+ struct stat script_stab;
+ struct stat sock_stab;
int r;
r = lstat(script, &script_stab);
if (r) err(127,"lstat script (%s)",script);
- r = lstat(socket_path, &sock_stab);
- if (r) {
- if ((errno == ENOENT))
- return 0; /* well, no garbage then */
- err(127,"stat socket (%s)",socket_path);
- }
-
if (stab_isnewer(&script_stab, &sock_stab))
return 1;
return 0;
}
+static bool check_garbage(void) {
+ struct stat sock_stab;
+ int r;
+
+ r = lstat(socket_path, &sock_stab);
+ if (r) {
+ if ((errno == ENOENT))
+ return 0; /* well, no garbage then */
+ err(127,"stat socket (%s)",socket_path);
+ }
+
+ return check_garbage_vs(&sock_stab);
+}
+
+static void tidy_garbage(void) {
+ /* We lock l<ident> and re-check. The effect of this is that each
+ * stale socket is removed only once. So unless multiple updates to
+ * the script happen rapidly, we can't be racing with the cgi-fcgi
+ * (which is recreating the socket */
+ int lockfd = -1;
+ int r;
+
+ const char *lock_path = m_asprintf("%s/l%s",run_base,ident);
+
+ lockfd = open(lock_path, O_CREAT|O_RDWR, 0600);
+ if (lockfd<0) err(127,"create lock (%s)", lock_path);
+
+ r = flock(lockfd, LOCK_EX);
+ if (r) err(127,"lock lock (%s)", lock_path);
+
+ if (check_garbage()) {
+ r = unlink(socket_path);
+ if (r) {
+ if (!(errno == ENOENT))
+ err(127,"remove out-of-date socket (%s)", socket_path);
+ }
+ }
+
+ r = close(lockfd);
+ if (r) errx(127,"close lock (%s)", lock_path);
+}
+
+static void make_stderr_copy(void) {
+ stderr_copy = dup(2);
+ if (stderr_copy < 0) err(127,"dup stderr (for copy for stage2)");
+}
+
static void shbang_opts(const char *const **argv_io,
const struct cmdinfo *cmdinfos) {
myopt(argv_io, cmdinfos);
if (!interp) errx(127,"need interpreter argument");
}
+/* stage2 predeclarations */
+static void record_baseline_time(void);
+static void become_pgrp(void);
+static void setup_handlers(void);
+static void spawn_script(void);
+static void queue_alarm(void);
+static void await_something(void);
+
int main(int argc, const char *const *argv) {
- const char *smashedopt;
+ const char *smashedopt, *us;
+ int r;
+
+ us = argv[0];
+
+ if (argc>=4 && !strcmp(argv[1],"--stage2")) {
+ ++argv;
+ stage2 = 1;
+
+ int stderrfd = atoi(*++argv);
+ r = dup2(stderrfd, 2);
+ assert(r==2);
+
+ r = open("/dev/null",O_WRONLY);
+ if (r<0) err(127,"open /dev/null as stdout");
+ if (r>=3) close(r);
+ else if (r!=1) errx(127,"open /dev/null for stdout gave bad fd %d",r);
+
+ socket_path = *++argv;
+ }
if (argc>=2 &&
(smashedopt = argv[1]) &&
if (!script) errx(127,"need script argument");
if (*argv) errx(127,"too many arguments");
- find_socket_path();
+ if (!stage2) {
+
+ find_socket_path();
+
+ bool isgarbage = check_garbage();
- check_garbage();
+ if (debugmode) {
+ printf("socket: %s\n",socket_path);
+ printf("interp: %s\n",interp);
+ printf("script: %s\n",script);
+ printf("garbage: %d\n",isgarbage);
+ exit(0);
+ }
+
+ if (isgarbage)
+ tidy_garbage();
+
+ make_stderr_copy();
+
+ execlp("cgi-fcgi",
+ "cgi-fcti", "-connect", socket_path,
+ us, "--stage2",
+ m_asprintf("-c%d", check_interval),
+ m_asprintf("%d", stderr_copy), socket_path,
+ interp, script,
+ (char*)0);
+ err(127,"exec cgi-fcgi");
+
+ } else { /*stage2*/
+
+ record_baseline_time();
+ become_pgrp();
+ setup_handlers();
+ spawn_script();
+ queue_alarm();
+ await_something();
+ abort();
- if (debugmode) {
- printf("socket: %s\n",socket_path);
- printf("interp: %s\n",interp);
- printf("script: %s\n",script);
}
+}
- exit(0);
+/* stage2 */
+
+/* It is most convenient to handle the recheck timeout, as well as
+ * child death, in signal handlers. Our signals all block each other,
+ * and the main program has signals blocked except in sigsuspend, so
+ * we don't need to worry about async-signal-safety, or errno. */
+
+static struct stat baseline_time;
+static pid_t script_child, stage2_pgrp;
+static bool out_of_date;
+
+static void record_baseline_time(void) {
+#ifdef st_mtime
+ int r = clock_gettime(CLOCK_REALTIME, &baseline_time.st_mtim);
+ if (r) err(127,"(stage2) clock_gettime");
+#else
+ baseline_time.st_mtime = time(NULL);
+ if (baseline_time.st_mtime == (time_t)-1) err(127,"(stage2) time()");
+#endif
+}
+
+static void become_pgrp(void) {
+ int r;
+
+ stage2_pgrp = getpid();
+
+ r = setpgid(0,0);
+ if (r) err(127,"(stage2) setpgid");
+}
+
+static void atexit_handler(void) {
+ int r;
+
+ sighandler_t sigr = signal(SIGTERM,SIG_IGN);
+ if (sigr == SIG_ERR) warn("(stage2) signal(SIGTERM,SIG_IGN)");
+
+ r = killpg(stage2_pgrp,SIGTERM);
+ if (r) warn("(stage) killpg failed");
+}
+
+static void alarm_handler(int dummy) {
+ if (out_of_date)
+ /* second timeout */
+ exit(0); /* transfers control to atexit_handler */
+
+ out_of_date = check_garbage_vs(&baseline_time);
+ queue_alarm();
+}
+
+static void child_handler(int dummy) {
+ for (;;) {
+ int status;
+ pid_t got = waitpid(-1, &status, WNOHANG);
+ if (got == (pid_t)-1) err(127,"(stage2) waitpid");
+ if (got != script_child) {
+ warn("(stage2) waitpid got status %d for unknown child [%lu]",
+ status, (unsigned long)got);
+ continue;
+ }
+ if (WIFEXITED(status)) {
+ int v = WEXITSTATUS(status);
+ if (v) warn("program failed with error exit status %d", v);
+ exit(status);
+ } else if (WIFSIGNALED(status)) {
+ int s = WTERMSIG(status);
+ err(status & 0xff, "program died due to fatal signal %s%s",
+ strsignal(s), WCOREDUMP(status) ? " (core dumped" : "");
+ } else {
+ err(127, "program failed with crazy wait status %#x", status);
+ }
+ }
+ exit(127);
+}
+
+static void setup_handlers(void) {
+ struct sigaction sa;
+ int r;
+
+ r = atexit(atexit_handler);
+ if (r) err(127,"(stage2) atexit");
+
+ sigemptyset(&sa.sa_mask);
+ sigaddset(&sa.sa_mask, SIGALRM);
+ sigaddset(&sa.sa_mask, SIGCHLD);
+ sa.sa_flags = 0;
+
+ r = sigprocmask(SIG_BLOCK, &sa.sa_mask, 0);
+ if (r) err(127,"(stage2) sigprocmask(SIG_BLOCK,)");
+
+ sa.sa_handler = alarm_handler;
+ r = sigaction(SIGALRM, &sa, 0);
+ if (r) err(127,"(stage2) sigaction SIGALRM");
+
+ sa.sa_flags |= SA_NOCLDSTOP;
+ sa.sa_handler = child_handler;
+ r = sigaction(SIGCHLD, &sa, 0);
+ if (r) err(127,"(stage2) sigaction SIGCHLD");
+}
+
+static void spawn_script(void) {
+ script_child = fork();
+ if (script_child == (pid_t)-1) err(127,"(stage2) fork");
+ if (!script_child) {
+ execlp(interp,
+ interp, script, (char*)0);
+ err(127,"(stage2) exec interpreter (`%s', for `%s')\n",interp,script);
+ }
+}
+
+static void queue_alarm(void) {
+ alarm(check_interval);
+}
+
+static void await_something(void) {
+ int r;
+ sigset_t mask;
+ sigemptyset(&mask);
+
+ for (;;) {
+ r = sigsuspend(&mask);
+ assert(r==-1);
+ if (r != EINTR) err(127,"(stage2) sigsuspend");
+ }
}
~ian / chiark-utils.git / blobdiff