+ my $check_commit_hook="";
+ my $pre_exec="";
+ if ($config{post_commit}) {
+ # Optimise checking !commit_hook_enabled() ,
+ # so that ikiwiki does not have to be started if the
+ # hook is disabled.
+ #
+ # Note that perl's flock may be implemented using fcntl
+ # or lockf on some systems. If so, and if there is no
+ # interop between the locking systems, the true C flock will
+ # always succeed, and this optimisation won't work.
+ # The perl code will later correctly check the lock,
+ # so the right thing will still happen, though without
+ # the benefit of this optimisation.
+ $check_commit_hook=<<"EOF";
+ {
+ int fd=open("$config{wikistatedir}/commitlock", O_CREAT | O_RDWR, 0666);
+ if (fd != -1) {
+ if (flock(fd, LOCK_SH | LOCK_NB) != 0)
+ exit(0);
+ close(fd);
+ }
+ }
+EOF
+ }
+ elsif ($config{cgi}) {
+ # Avoid more than one ikiwiki cgi running at a time by
+ # taking a cgi lock. Since ikiwiki uses several MB of
+ # memory, a pile up of processes could cause thrashing
+ # otherwise. The fd of the lock is stored in
+ # IKIWIKI_CGILOCK_FD so unlockwiki can close it.
+ #
+ # A lot of cgi wrapper processes can potentially build
+ # up and clog an otherwise unloaded web server. To
+ # partially avoid this, when a GET comes in and the lock
+ # is already held, rather than blocking a html page is
+ # constructed that retries. This is enabled by setting
+ # cgi_overload_delay.
+ if (defined $config{cgi_overload_delay} &&
+ $config{cgi_overload_delay} =~/^[0-9]+/) {
+ my $i=int($config{cgi_overload_delay});
+ $pre_exec.="#define CGI_OVERLOAD_DELAY $i\n"
+ if $i > 0;
+ my $msg=gettext("Please wait");
+ $msg=~s/"/\\"/g;
+ $pre_exec.='#define CGI_PLEASE_WAIT_TITLE "'.$msg."\"\n";
+ if (defined $config{cgi_overload_message} && length $config{cgi_overload_message}) {
+ $msg=$config{cgi_overload_message};
+ $msg=~s/"/\\"/g;
+ }
+ $pre_exec.='#define CGI_PLEASE_WAIT_BODY "'.$msg."\"\n";
+ }
+ $pre_exec.=<<"EOF";
+ lockfd=open("$config{wikistatedir}/cgilock", O_CREAT | O_RDWR, 0666);
+ if (lockfd != -1) {
+#ifdef CGI_OVERLOAD_DELAY
+ char *request_method = getenv("REQUEST_METHOD");
+ if (request_method && strcmp(request_method, "GET") == 0) {
+ if (lockf(lockfd, F_TLOCK, 0) == 0) {
+ set_cgilock_fd(lockfd);
+ }
+ else {
+ printf("Content-Type: text/html\\nRefresh: %i; URL=%s\\n\\n<html><head><title>%s</title><head><body><p>%s</p></body></html>",
+ CGI_OVERLOAD_DELAY,
+ getenv("REQUEST_URI"),
+ CGI_PLEASE_WAIT_TITLE,
+ CGI_PLEASE_WAIT_BODY);
+ exit(0);
+ }
+ }
+ else if (lockf(lockfd, F_LOCK, 0) == 0) {
+ set_cgilock_fd(lockfd);
+ }
+#else
+ if (lockf(lockfd, F_LOCK, 0) == 0) {
+ set_cgilock_fd(lockfd);
+ }
+#endif
+ }
+EOF
+ }
+
+ my $set_background_command='';
+ if (defined $config{wrapper_background_command} &&
+ length $config{wrapper_background_command}) {
+ my $background_command=delete $config{wrapper_background_command};
+ $set_background_command=~s/"/\\"/g;
+ $set_background_command='#define BACKGROUND_COMMAND "'.$background_command.'"';