Ignore SIGHUP when running as a daemon

configure.ac

@@ -292,6 +292,7 @@ fi
 AC_CHECK_FUNCS(mlockall)
 AC_CHECK_FUNCS(getpagesizes)
 AC_CHECK_FUNCS(memcntl)
+AC_CHECK_FUNCS(sigignore)
 
 AC_DEFUN([AC_C_ALIGNMENT],
 [AC_CACHE_CHECK(for alignment, ac_cv_c_alignment,
@@ -353,9 +354,11 @@ if test "$ICC" = "yes"
 then
    dnl ICC trying to be gcc.
    CFLAGS="$CFLAGS -diag-disable 187 -Wall -Werror"
+   AC_DEFINE([_GNU_SOURCE],[1],[find sigignore on Linux])
 elif test "$GCC" = "yes"
 then
   CFLAGS="$CFLAGS -Wall -Werror -pedantic -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations -Wredundant-decls"
+  AC_DEFINE([_GNU_SOURCE],[1],[find sigignore on Linux])
 elif test "$SUNCC" = "yes"
 then
   CFLAGS="$CFLAGS -errfmt=error -errwarn -errshort=tags"

internal_tests.c

@@ -1,8 +1,9 @@
 /* -*- Mode: C; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */
-
+#undef NDEBUG
 #include <assert.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <signal.h>
 
 #include "memcached.h"
 
@@ -104,11 +105,33 @@ static void test_safe_strtol() {
   assert(val == 123);
 }
 
+static void test_issue_44(void) {
+    char pidfile[80];
+    char buffer[256];
+    sprintf(pidfile, "/tmp/memcached.%d", getpid());
+    sprintf(buffer, "./memcached-debug -p 0 -P %s -d", pidfile);
+    assert(system(buffer) == 0);
+    sleep(1);
+    FILE *fp = fopen(pidfile, "r");
+    assert(fp);
+    assert(fgets(buffer, sizeof(buffer), fp));
+    fclose(fp);
+    pid_t pid = atol(buffer);
+    assert(kill(pid, 0) == 0);
+    assert(kill(pid, SIGHUP) == 0);
+    sleep(1);
+    assert(kill(pid, 0) == 0);
+    assert(kill(pid, SIGTERM) == 0);
+    assert(remove(pidfile) == 0);
+}
+
+
 int main(int argc, char **argv) {
   test_safe_strtoull();
   test_safe_strtoll();
   test_safe_strtoul();
   test_safe_strtol();
+  test_issue_44();
   printf("OK.\n");
   return 0;
 }

memcached.c

@@ -3895,6 +3895,18 @@ static void sig_handler(const int sig) {
     exit(EXIT_SUCCESS);
 }
 
+#ifndef HAVE_SIGIGNORE
+static int sigignore(int sig) {
+    struct sigaction sa = { .sa_handler = SIG_IGN, .sa_flags = 0 };
+
+    if (sigemptyset(&sa.sa_mask) == -1 || sigaction(sig, &sa, 0) == -1) {
+        return -1;
+    }
+    return 0;
+}
+#endif
+
+
 #if defined(HAVE_GETPAGESIZES) && defined(HAVE_MEMCNTL)
 /*
  * On systems that supports multiple page sizes we may reduce the
@@ -3945,7 +3957,6 @@ int main (int argc, char **argv) {
     char *username = NULL;
     char *pid_file = NULL;
     struct passwd *pw;
-    struct sigaction sa;
     struct rlimit rlim;
     /* listening sockets */
     static int *l_socket = NULL;
@@ -4159,9 +4170,10 @@ int main (int argc, char **argv) {
     /* daemonize if requested */
     /* if we want to ensure our ability to dump core, don't chdir to / */
     if (do_daemonize) {
-        int res;
-        res = daemonize(maxcore, settings.verbose);
-        if (res == -1) {
+        if (sigignore(SIGHUP) == -1) {
+            perror("Failed to ignore SIGHUP");
+        }
+        if (daemonize(maxcore, settings.verbose) == -1) {
             fprintf(stderr, "failed to daemon() in order to daemonize\n");
             exit(EXIT_FAILURE);
         }
@@ -4196,10 +4208,7 @@ int main (int argc, char **argv) {
      * ignore SIGPIPE signals; we can use errno == EPIPE if we
      * need that information
      */
-    sa.sa_handler = SIG_IGN;
-    sa.sa_flags = 0;
-    if (sigemptyset(&sa.sa_mask) == -1 ||
-        sigaction(SIGPIPE, &sa, 0) == -1) {
+    if (sigignore(SIGPIPE) == -1) {
         perror("failed to ignore SIGPIPE; sigaction");
         exit(EX_OSERR);
     }