2 * "Interpreter" that you can put in #! like this
3 * #!/usr/bin/cgi-fcgi-interp [<options>] <interpreter>
6 * cgi-fcgi-interp.[ch] - Convenience wrapper for cgi-fcgi
8 * Copyright 2016 Ian Jackson
9 * Copyright 1982,1986,1993 The Regents of the University of California
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; either version 3 of the License, or
14 * (at your option) any later version.
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
21 * You should have received a copy of the GNU General Public
22 * License along with this file; if not, consult the Free Software
23 * Foundation's website at www.fsf.org, or the GNU Project website at
26 * See below for a BSD 3-clause notice regarding timespeccmp.
29 * The result is a program which looks, when executed via the #!
30 * line, like a CGI program. But the script inside will be executed
31 * via <interpreter> in an fcgi context.
36 * The real interpreter to use. Eg "perl". Need not
37 * be an absolute path; will be fed to execvp.
40 * Add <ident-info> to the unique identifying information for
41 * this fcgi program. May be repeated; order is significant.
43 * -E<ident-info-env-var>
44 * Look <ident-info-env-var> up in the environment and add
45 * <ident-info-env-var>=<value> as if specified with -G. If
46 * the variable is unset in the environment, it is as if
47 * -G<ident-info-env-var> was specified.
50 * Use <ident> rather than hex(sha256(<interp>\0<script>\0))
51 * as the basename of the leafname of the fcgi rendezvous
52 * socket. If <ident> contains only hex digit characters it
53 * ought to be no more than 32 characters. <ident> should
54 * not contain spaces or commas (see below).
57 * Start <numservers> instances of the program. This
58 * determines the maximum concurrency. (Note that unlike
59 * speedy, the specified number of servers is started
60 * right away.) The default is 4.
63 * Stale server check interval, in seconds. The worker
64 * process group will get a SIGTERM when it is no longer
65 * needed to process new requests. Ideally it would continue
66 * to serve any existing requests. The SIGTERM will arrive no
67 * earlier than <interval> after the last request arrived at
68 * the containing webserver. Default is 300.
71 * Debug mode. Do not actually run program. Instead, print
72 * out what we would do.
74 * <options> and <interpreter> can be put into a single argument
75 * to cgi-fcgi-interp, separated by spaces or commas. <interpreter>
78 * cgi-fcgi-interp automatically expires old sockets, including
79 * ones where the named script is out of date.
82 * Uses one of two directories
83 * /var/run/user/<UID>/cgi-fcgi-interp/
84 * ~/.cgi-fcgi-interp/<node>/
85 * and inside there uses these paths
87 * l<ident> used to lock around garbage collection
89 * If -M<ident> is not specified then an initial substring of the
90 * lowercase hex of the sha256 of <interp>\0<script>\0 is
91 * used. The substring is chosen so that the whole path is 10 bytes
92 * shorter than sizeof(sun_path). But always at least 33 characters.
94 * <node> is truncated at the first `.' and after the first 32
98 * - see if /var/run/user exists
99 * if so, lstat /var/run/user/<UID> and check that
100 * we own it and it's X700; if not, fail
101 * if it's ok then <base> is /var/run/user/<UID>
102 * otherwise, look for and maybe create ~/.cgi-fcgi-interp
103 * (where ~ is HOME or from getpwuid)
104 * and then <base> is ~/.cgi-fcgi-interp/<node>
105 * - calculate pathname (checking <ident> length is OK)
106 * - check for and maybe create <base>
107 * - stat and lstat the <script>
108 * - stat the socket and check its timestamp
109 * if it is too old, unlink it
110 * - dup stderr, mark no cloexec
111 * - set CHIARKUTILS_CGIFCGIINTERP_STAGE2=<stderr-copy-fd>
112 * - run cgi-fcgi -connect SOCKET <script>
114 * When CHIARKUTILS_CGIFCGIINTERP_STAGE2 is set, --stage2 does this:
115 * - dup2 <was-stderr> to fd 2
116 * - open /dev/null and expect fd 1 (and if not, close it)
117 * - become a new process group
118 * - lstat <socket> to find its inum, mtime
119 * - fork/exec <interp> <script>
120 * - periodically lstat <interp> and <script> and
121 * if mtime is newer than our start time
122 * kill process group (at second iteration)
127 static const char *stage2;
129 const struct cmdinfo cmdinfos[]= {
130 { "help", 0, .call=of_help },
131 { 0, 'g', 1, .sassignto= &ident },
132 { 0, 'G', 1, .call= ident_addstring },
133 { 0, 'E', 1, .call= off_ident_addenv },
134 { 0, 'M', 1, .call=of_iassign, .iassignto= &numservers },
135 { 0, 'D', 0, .iassignto= &debugmode, .arg= 1 },
136 { 0, 'c', 1, .call=of_iassign, .iassignto= &check_interval },
140 void fusagemessage(FILE *f) {
141 fprintf(f, "usage: #!/usr/bin/cgi-fcgi-interp [<options>]\n");
144 static int stderr_copy;
146 static void make_stderr_copy(void) {
147 stderr_copy = dup(2);
148 if (stderr_copy < 0) diee("dup stderr (for copy for stage2)");
151 static void prep_stage2(void) {
154 const char *stage2_val = m_asprintf("%d", stderr_copy);
155 r = setenv(STAGE2_VAR, stage2_val, 1);
156 if (r) diee("set %s (to announce to stage2)", STAGE2_VAR);
159 /* stage2 predeclarations */
160 static void record_baseline_time(void);
161 static void become_pgrp(void);
162 static void setup_handlers(void);
163 static void spawn_script(void);
164 static void queue_alarm(void);
165 static void start_logging(void);
166 static void await_something(void);
168 int main(int argc, const char *const *argv) {
171 stage2 = getenv(STAGE2_VAR);
173 int stderrfd = atoi(stage2);
176 r = dup2(stderrfd, 2);
179 r = open("/dev/null",O_WRONLY);
180 if (r<0) diee("open /dev/null as stdout");
182 else if (r!=1) die("open /dev/null for stdout gave bad fd %d",r);
185 if (r) diee("close saved stderr fd");
188 script = process_opts(argc, argv);
194 bool isgarbage = check_garbage();
197 printf("socket: %s\n",socket_path);
198 printf("interp: %s\n",interp);
199 printf("script: %s\n",script);
200 printf("garbage: %d\n",isgarbage);
211 "cgi-fcgi", "-connect", socket_path,
213 m_asprintf("%d", numservers),
215 diee("exec cgi-fcgi");
219 record_baseline_time();
233 /* It is most convenient to handle the recheck timeout, as well as
234 * child death, in signal handlers. Our signals all block each other,
235 * and the main program has signals blocked except in sigsuspend, so
236 * we don't need to worry about async-signal-safety, or errno. */
238 static struct stat baseline_time;
239 static pid_t script_child, stage2_pgrp;
240 static bool out_of_date;
243 static void record_baseline_time(void) {
244 stab_mtimenow(&baseline_time);
247 static void become_pgrp(void) {
250 stage2_pgrp = getpid();
253 if (r) diee("(stage2) setpgid");
256 static void atexit_handler(void) {
259 sighandler_t sigr = signal(SIGTERM,SIG_IGN);
260 if (sigr == SIG_ERR) warninge("(stage2) signal(SIGTERM,SIG_IGN)");
262 r = killpg(stage2_pgrp,SIGTERM);
263 if (r) warninge("(stage) killpg failed");
266 static void alarm_handler(int dummy) {
269 exit(0); /* transfers control to atexit_handler */
271 out_of_date = check_garbage_vs(&baseline_time);
275 static void child_handler(int dummy) {
278 pid_t got = waitpid(-1, &status, WNOHANG);
279 if (got == (pid_t)-1) diee("(stage2) waitpid");
280 if (got != script_child) {
281 warning("(stage2) waitpid got status %d for unknown child [%lu]",
282 status, (unsigned long)got);
285 if (WIFEXITED(status)) {
286 int v = WEXITSTATUS(status);
287 if (v) warning("program failed with error exit status %d", v);
289 } else if (WIFSIGNALED(status)) {
290 int s = WTERMSIG(status);
291 warning("program died due to fatal signal %s%s",
292 strsignal(s), WCOREDUMP(status) ? " (core dumped" : "");
293 assert(status & 0xff);
296 die("program failed with crazy wait status %#x", status);
302 static void setup_handlers(void) {
306 r = atexit(atexit_handler);
307 if (r) diee("(stage2) atexit");
309 sigemptyset(&sa.sa_mask);
310 sigaddset(&sa.sa_mask, SIGALRM);
311 sigaddset(&sa.sa_mask, SIGCHLD);
314 r = sigprocmask(SIG_BLOCK, &sa.sa_mask, 0);
315 if (r) diee("(stage2) sigprocmask(SIG_BLOCK,)");
317 sa.sa_handler = alarm_handler;
318 r = sigaction(SIGALRM, &sa, 0);
319 if (r) diee("(stage2) sigaction SIGALRM");
321 sa.sa_flags |= SA_NOCLDSTOP;
322 sa.sa_handler = child_handler;
323 r = sigaction(SIGCHLD, &sa, 0);
324 if (r) diee("(stage2) sigaction SIGCHLD");
327 static void spawn_script(void) {
332 if (r) diee("(stage2) pipe");
334 script_child = fork();
335 if (script_child == (pid_t)-1) diee("(stage2) fork");
337 r = close(errpipes[0]);
338 if (r) diee("(stage2 child) close errpipes[0]");
340 r = dup2(errpipes[1], 2);
341 if (r != 2) diee("(stage2 child) dup2 stderr");
344 interp, script, (char*)0);
345 diee("(stage2) exec interpreter (`%s', for `%s')\n",interp,script);
348 r = close(errpipes[1]);
349 if (r) diee("(stage2) close errpipes[1]");
351 errpipe = errpipes[0];
352 r = fcntl(errpipe, F_SETFL, O_NONBLOCK);
353 if (r) diee("(stage2) set errpipe nonblocking");
356 static void queue_alarm(void) {
357 alarm(check_interval);
360 static void start_logging(void) {
363 openlog(script, LOG_NOWAIT|LOG_PID, LOG_USER);
366 if (r!=2) diee("dup2 stdout to stderr");
369 static void errpipe_readable(void) {
370 static char buf[1024];
373 /* %: does not contain newlines
377 /* %%%%%%%%%%%__________________ */
381 int avail = sizeof(buf) - pending;
382 ssize_t got = read(errpipe, buf+pending, avail);
384 if (errno==EINTR) continue;
385 else if (errno==EWOULDBLOCK || errno==EAGAIN) return;
386 else diee("(stage2) errpipe read");
389 warning("program closed its stderr fd");
393 int scanned = pending;
397 const char *newline = memchr(buf+scanned, '\n', pending-scanned);
400 printupto = newline-buf;
402 } else if (!eaten && pending==sizeof(buf)) { /* overflow */
408 syslog(LOG_ERR,"stderr: %.*s", printupto-eaten, buf+eaten);
413 memmove(buf, buf+eaten, pending);
417 static void await_something(void) {
426 FD_SET(errpipe, &rfds);
427 r = pselect(errpipe+1, &rfds,0,0, 0, &mask);
429 if (errno != EINTR) diee("(stage2) sigsuspend");
433 assert(FD_ISSET(errpipe, &rfds));