X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=chiark-utils.git;a=blobdiff_plain;f=cprogs%2Fcgi-fcgi-interp.c;h=f59640f4305eb86342d135462f7aa02e3a44e2c5;hp=40cedb43e1402fd5f5412c8e37dea66284cadea0;hb=1e17ba9014e80fc58acfa88b20e8fd2744d994d5;hpb=cdcf090593a4598805cad2f81cf248f3cf5081ba

diff --git a/cprogs/cgi-fcgi-interp.c b/cprogs/cgi-fcgi-interp.c
index 40cedb4..f59640f 100644
--- a/cprogs/cgi-fcgi-interp.c
+++ b/cprogs/cgi-fcgi-interp.c
@@ -113,8 +113,8 @@
  *  - become a new process group
  *  - lstat <socket> to find its inum, mtime
  *  - fork/exec <interp> <script>
- *  - periodically lstat <socket> and
- *      if inum, mtime have changed
+ *  - periodically lstat <interp> and <script> and
+ *      if mtime is newer than our start time
  *      kill process group (at second iteration)
  */
 
@@ -138,6 +138,9 @@
 #include <fcntl.h>
 #include <pwd.h>
 #include <err.h>
+#include <time.h>
+#include <signal.h>
+#include <sys/wait.h>
 	
 #include <nettle/sha.h>
 
@@ -191,7 +194,7 @@ static const struct cmdinfo cmdinfos[]= {
 
 static uid_t us;
 static const char *run_base, *script, *socket_path;
-static struct stat sock_stab;
+static int stderr_copy;
 
 static bool find_run_base_var_run(void) {
   struct stat stab;
@@ -345,20 +348,14 @@ static bool stab_isnewer(const struct stat *a, const struct stat *b) {
 #endif
 }
 
-static bool check_garbage(void) {
+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;
 
@@ -373,6 +370,20 @@ static bool check_garbage(void) {
   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
@@ -401,6 +412,11 @@ static void tidy_garbage(void) {
   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);
@@ -409,12 +425,21 @@ static void shbang_opts(const char *const **argv_io,
   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, *us;
+  int r;
 
   us = argv[0];
 
-  if (argv>=4 && !strcmp(argv[1],"--stage2")) {
+  if (argc>=4 && !strcmp(argv[1],"--stage2")) {
     ++argv;
     stage2 = 1;
 
@@ -425,9 +450,9 @@ int main(int argc, const char *const *argv) {
     r = open("/dev/null",O_WRONLY);
     if (r<0) err(127,"open /dev/null as stdout");
     if (r>=3) close(r);
-    else if (r!=) errx(127,"open /dev/null gave bad fd %d",r);
+    else if (r!=1) errx(127,"open /dev/null for stdout gave bad fd %d",r);
 
-    sock_path = *++argv;
+    socket_path = *++argv;
   }
 
   if (argc>=2 &&
@@ -484,28 +509,151 @@ int main(int argc, const char *const *argv) {
     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", copy_stderr), socket_path,
+	   m_asprintf("%d", stderr_copy), socket_path,
 	   interp, script,
 	   (char*)0);
     err(127,"exec cgi-fcgi");
     
   } else { /*stage2*/
 
+    record_baseline_time();
     become_pgrp();
-    check_socket_baseline();
+    setup_handlers();
     spawn_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);
+    queue_alarm();
+    await_something();
+    abort();
+
   }
+}
 
+/* 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");
   }
 }