2 * "Interpreter" that you can put in #! like this
3 * #!/usr/bin/cgi-fcgi-interp [<options>] <interpreter>
6 * cgi-fcgi-interp [<option> ..] <interpreter> <script> [<ignored> ...]
7 * cgi-fcgi-interp [<option>,..],<interpreter> <script> [<ignored> ...]
8 * cgi-fcgi-interp '[<option> ..] <interpreter>' <script> [<ignored> ...]
11 * cgi-fcgi-interp.[ch] - Convenience wrapper for cgi-fcgi
13 * Copyright 2016 Ian Jackson
14 * Copyright 1982,1986,1993 The Regents of the University of California
16 * This program is free software; you can redistribute it and/or modify
17 * it under the terms of the GNU General Public License as published by
18 * the Free Software Foundation; either version 3 of the License, or
19 * (at your option) any later version.
21 * This program is distributed in the hope that it will be useful,
22 * but WITHOUT ANY WARRANTY; without even the implied warranty of
23 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
24 * GNU General Public License for more details.
26 * You should have received a copy of the GNU General Public
27 * License along with this file; if not, consult the Free Software
28 * Foundation's website at www.fsf.org, or the GNU Project website at
31 * See below for a BSD 3-clause notice regarding timespeccmp.
34 * The result is a program which looks, when executed via the #!
35 * line, like a CGI program. But the script inside will be executed
36 * via <interpreter> in an fcgi context.
41 * The real interpreter to use. Eg "perl". Need not
42 * be an absolute path; will be fed to execvp.
45 * Add <ident-info> to the unique identifying information for
46 * this fcgi program. May be repeated; order is significant.
48 * -E<ident-info-env-var>
49 * Look <ident-info-env-var> up in the environment and add
50 * <ident-info-env-var>=<value> as if specified with -G. If
51 * the variable is unset in the environment, it is as if
52 * -G<ident-info-env-var> was specified.
55 * Use <ident> rather than hex(sha256(<interp>\0<script>\0))
56 * as the basename of the leafname of the fcgi rendezvous
57 * socket. If <ident> contains only hex digit characters it
58 * ought to be no more than 32 characters. <ident> should
59 * not contain spaces or commas (see below).
62 * Start <numservers> instances of the program. This
63 * determines the maximum concurrency. (Note that unlike
64 * speedy, the specified number of servers is started
65 * right away.) The default is 4.
68 * Stale server check interval, in seconds. The worker
69 * process group will get a SIGTERM when it is no longer
70 * needed to process new requests. Ideally it would continue
71 * to serve any existing requests. The SIGTERM will arrive no
72 * earlier than <interval> after the last request arrived at
73 * the containing webserver. Default is 300.
76 * Debug mode. Do not actually run program. Instead, print
77 * out what we would do.
79 * <options> and <interpreter> can be put into a single argument
80 * to cgi-fcgi-interp, separated by spaces or commas. <interpreter>
83 * cgi-fcgi-interp automatically expires old sockets, including
84 * ones where the named script is out of date.
87 * Uses one of two directories
88 * /var/run/user/<UID>/cgi-fcgi-interp/
89 * ~/.cgi-fcgi-interp/<node>/
90 * and inside there uses these paths
92 * l<ident> used to lock around garbage collection
94 * If -M<ident> is not specified then an initial substring of the
95 * lowercase hex of the sha256 of <interp>\0<script>\0 is
96 * used. The substring is chosen so that the whole path is 10 bytes
97 * shorter than sizeof(sun_path). But always at least 33 characters.
99 * <node> is truncated at the first `.' and after the first 32
103 * - see if /var/run/user exists
104 * if so, lstat /var/run/user/<UID> and check that
105 * we own it and it's X700; if not, fail
106 * if it's ok then <base> is /var/run/user/<UID>
107 * otherwise, look for and maybe create ~/.cgi-fcgi-interp
108 * (where ~ is HOME or from getpwuid)
109 * and then <base> is ~/.cgi-fcgi-interp/<node>
110 * - calculate pathname (checking <ident> length is OK)
111 * - check for and maybe create <base>
112 * - stat and lstat the <script>
113 * - stat the socket and check its timestamp
114 * if it is too old, unlink it
115 * - dup stderr, mark no cloexec
116 * - set CHIARKUTILS_CGIFCGIINTERP_STAGE2=<stderr-copy-fd>
117 * - run cgi-fcgi -connect SOCKET <script>
119 * When CHIARKUTILS_CGIFCGIINTERP_STAGE2 is set, --stage2 does this:
120 * - dup2 <was-stderr> to fd 2
121 * - open /dev/null and expect fd 1 (and if not, close it)
122 * - become a new process group
123 * - lstat <socket> to find its inum, mtime
124 * - fork/exec <interp> <script>
125 * - periodically lstat <interp> and <script> and
126 * if mtime is newer than our start time
127 * kill process group (at second iteration)
132 #define STAGE2_VAR "CHIARKUTILS_CGIFCGIINTERP_STAGE2"
134 static const char *stage2;
136 const char our_name[] = "cgi-fcgi-interp";
138 static int numservers=4, debugmode;
139 static int check_interval=300;
141 const struct cmdinfo cmdinfos[]= {
143 { 0, 'M', 1, .call=of_iassign, .iassignto= &numservers },
144 { 0, 'D', 0, .iassignto= &debugmode, .arg= 1 },
145 { 0, 'c', 1, .call=of_iassign, .iassignto= &check_interval },
149 void fusagemessage(FILE *f) {
150 fprintf(f, "usage: #!/usr/bin/cgi-fcgi-interp [<options>]\n");
153 void ident_addinit(void) {
156 static int stderr_copy;
158 static void make_stderr_copy(void) {
159 stderr_copy = dup(2);
160 if (stderr_copy < 0) diee("dup stderr (for copy for stage2)");
163 static void prep_stage2(void) {
166 const char *stage2_val = m_asprintf("%d", stderr_copy);
167 r = setenv(STAGE2_VAR, stage2_val, 1);
168 if (r) diee("set %s (to announce to stage2)", STAGE2_VAR);
173 static bool stab_isnewer(const struct stat *a, const struct stat *b) {
175 fprintf(stderr,"stab_isnewer mtim %lu.%06lu %lu.06%lu\n",
176 (unsigned long)a->st_mtim.tv_sec,
177 (unsigned long)a->st_mtim.tv_nsec,
178 (unsigned long)b->st_mtim.tv_sec,
179 (unsigned long)b->st_mtim.tv_nsec);
180 return timespeccmp(&a->st_mtim, &b->st_mtim, >);
183 static void stab_mtimenow(struct stat *out) {
184 int r = clock_gettime(CLOCK_REALTIME, &out->st_mtim);
185 if (r) diee("(stage2) clock_gettime");
187 fprintf(stderr,"stab_mtimenow mtim %lu.%06lu\n",
188 (unsigned long)out->st_mtim.tv_sec,
189 (unsigned long)out->st_mtim.tv_nsec);
192 #else /* !defined(st_mtime) */
194 static bool stab_isnewer(const struct stat *a, const struct stat *b) {
196 fprintf(stderr,"stab_isnewer mtime %lu %lu\n",
197 (unsigned long)a->st_mtime,
198 (unsigned long)b->st_mtime);
199 return a->st_mtime > b->st_mtime;
202 static void stab_mtimenow(struct stat *out) {
203 out->st_mtime = time(NULL);
204 if (out->st_mtime == (time_t)-1) diee("(stage2) time()");
206 fprintf(stderr,"stab_mtimenow mtime %lu\n",
207 (unsigned long)out->st_mtime);
210 #endif /* !defined(st_mtime) */
212 static bool check_garbage_vs(const struct stat *started) {
213 struct stat script_stab;
216 r = lstat(script, &script_stab);
217 if (r) diee("lstat script (%s)",script);
219 if (stab_isnewer(&script_stab, started))
222 if (S_ISLNK(script_stab.st_mode)) {
223 r = stat(script, &script_stab);
224 if (r) diee("stat script (%s0",script);
226 if (stab_isnewer(&script_stab, started))
233 static bool check_garbage(void) {
234 struct stat sock_stab;
237 r = lstat(socket_path, &sock_stab);
239 if ((errno == ENOENT))
240 return 0; /* well, no garbage then */
241 diee("stat socket (%s)",socket_path);
244 return check_garbage_vs(&sock_stab);
247 static void tidy_garbage(void) {
248 /* We lock l<ident> and re-check. The effect of this is that each
249 * stale socket is removed only once. So unless multiple updates to
250 * the script happen rapidly, we can't be racing with the cgi-fcgi
251 * (which is recreating the socket */
255 lockfd = acquire_lock();
257 if (check_garbage()) {
258 r = unlink(socket_path);
260 if (!(errno == ENOENT))
261 diee("remove out-of-date socket (%s)", socket_path);
266 if (r) diee("close lock (%s)", lock_path);
269 /* stage2 predeclarations */
270 static void record_baseline_time(void);
271 static void become_pgrp(void);
272 static void setup_handlers(void);
273 static void spawn_script(void);
274 static void queue_alarm(void);
275 static void start_logging(void);
276 static void await_something(void);
278 int main(int unused_argc, const char *const *argv) {
281 stage2 = getenv(STAGE2_VAR);
283 int stderrfd = atoi(stage2);
286 r = dup2(stderrfd, 2);
289 r = open("/dev/null",O_WRONLY);
290 if (r<0) diee("open /dev/null as stdout");
292 else if (r!=1) die("open /dev/null for stdout gave bad fd %d",r);
295 if (r) diee("close saved stderr fd");
299 if (!script) badusage("need script argument");
305 bool isgarbage = check_garbage();
308 printf("socket: %s\n",socket_path);
309 printf("interp: %s\n",interp);
310 printf("script: %s\n",script);
311 printf("garbage: %d\n",isgarbage);
322 "cgi-fcgi", "-connect", socket_path,
324 m_asprintf("%d", numservers),
326 diee("exec cgi-fcgi");
330 record_baseline_time();
344 /* It is most convenient to handle the recheck timeout, as well as
345 * child death, in signal handlers. Our signals all block each other,
346 * and the main program has signals blocked except in sigsuspend, so
347 * we don't need to worry about async-signal-safety, or errno. */
349 static struct stat baseline_time;
350 static pid_t script_child, stage2_pgrp;
351 static bool out_of_date;
354 static void record_baseline_time(void) {
355 stab_mtimenow(&baseline_time);
358 static void become_pgrp(void) {
361 stage2_pgrp = getpid();
364 if (r) diee("(stage2) setpgid");
367 static void atexit_handler(void) {
370 sighandler_t sigr = signal(SIGTERM,SIG_IGN);
371 if (sigr == SIG_ERR) warninge("(stage2) signal(SIGTERM,SIG_IGN)");
373 r = killpg(stage2_pgrp,SIGTERM);
374 if (r) warninge("(stage) killpg failed");
377 static void alarm_handler(int dummy) {
380 exit(0); /* transfers control to atexit_handler */
382 out_of_date = check_garbage_vs(&baseline_time);
386 static void child_handler(int dummy) {
389 pid_t got = waitpid(-1, &status, WNOHANG);
390 if (got == (pid_t)-1) diee("(stage2) waitpid");
391 if (got != script_child) {
392 warning("(stage2) waitpid got status %d for unknown child [%lu]",
393 status, (unsigned long)got);
396 if (WIFEXITED(status)) {
397 int v = WEXITSTATUS(status);
398 if (v) warning("program failed with error exit status %d", v);
400 } else if (WIFSIGNALED(status)) {
401 int s = WTERMSIG(status);
402 warning("program died due to fatal signal %s%s",
403 strsignal(s), WCOREDUMP(status) ? " (core dumped" : "");
404 assert(status & 0xff);
407 die("program failed with crazy wait status %#x", status);
413 static void setup_handlers(void) {
417 r = atexit(atexit_handler);
418 if (r) diee("(stage2) atexit");
420 sigemptyset(&sa.sa_mask);
421 sigaddset(&sa.sa_mask, SIGALRM);
422 sigaddset(&sa.sa_mask, SIGCHLD);
425 r = sigprocmask(SIG_BLOCK, &sa.sa_mask, 0);
426 if (r) diee("(stage2) sigprocmask(SIG_BLOCK,)");
428 sa.sa_handler = alarm_handler;
429 r = sigaction(SIGALRM, &sa, 0);
430 if (r) diee("(stage2) sigaction SIGALRM");
432 sa.sa_flags |= SA_NOCLDSTOP;
433 sa.sa_handler = child_handler;
434 r = sigaction(SIGCHLD, &sa, 0);
435 if (r) diee("(stage2) sigaction SIGCHLD");
438 static void spawn_script(void) {
443 if (r) diee("(stage2) pipe");
445 script_child = fork();
446 if (script_child == (pid_t)-1) diee("(stage2) fork");
448 r = close(errpipes[0]);
449 if (r) diee("(stage2 child) close errpipes[0]");
451 r = dup2(errpipes[1], 2);
452 if (r != 2) diee("(stage2 child) dup2 stderr");
455 interp, script, (char*)0);
456 diee("(stage2) exec interpreter (`%s', for `%s')\n",interp,script);
459 r = close(errpipes[1]);
460 if (r) diee("(stage2) close errpipes[1]");
462 errpipe = errpipes[0];
463 r = fcntl(errpipe, F_SETFL, O_NONBLOCK);
464 if (r) diee("(stage2) set errpipe nonblocking");
467 static void queue_alarm(void) {
468 alarm(check_interval);
471 static void start_logging(void) {
474 openlog(script, LOG_NOWAIT|LOG_PID, LOG_USER);
477 if (r!=2) diee("dup2 stdout to stderr");
480 static void errpipe_readable(void) {
481 static char buf[1024];
484 /* %: does not contain newlines
488 /* %%%%%%%%%%%__________________ */
492 int avail = sizeof(buf) - pending;
493 ssize_t got = read(errpipe, buf+pending, avail);
495 if (errno==EINTR) continue;
496 else if (errno==EWOULDBLOCK || errno==EAGAIN) return;
497 else diee("(stage2) errpipe read");
500 warning("program closed its stderr fd");
504 int scanned = pending;
508 const char *newline = memchr(buf+scanned, '\n', pending-scanned);
511 printupto = newline-buf;
513 } else if (!eaten && pending==sizeof(buf)) { /* overflow */
519 syslog(LOG_ERR,"stderr: %.*s", printupto-eaten, buf+eaten);
524 memmove(buf, buf+eaten, pending);
528 static void await_something(void) {
537 FD_SET(errpipe, &rfds);
538 r = pselect(errpipe+1, &rfds,0,0, 0, &mask);
540 if (errno != EINTR) diee("(stage2) sigsuspend");
544 assert(FD_ISSET(errpipe, &rfds));