Merge pull request #1924 from RincewindsHat/compiler_warnings_4_1

Centralise and refactor maxfd related functionality

4 files changed, 43 insertions, 9 deletions

diff --git a/lib/Makefile.am b/lib/Makefile.am
index 01d73a6..1a47395 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -7,7 +7,7 @@ noinst_LIBRARIES = libmonitoringplug.a
 AM_CPPFLAGS = -DNP_STATE_DIR_PREFIX=\"$(localstatedir)\" \
         -I$(srcdir) -I$(top_srcdir)/gl -I$(top_srcdir)/intl -I$(top_srcdir)/plugins
 
-libmonitoringplug_a_SOURCES = utils_base.c utils_disk.c utils_tcp.c utils_cmd.c
+libmonitoringplug_a_SOURCES = utils_base.c utils_disk.c utils_tcp.c utils_cmd.c maxfd.c
 EXTRA_DIST = utils_base.h utils_disk.h utils_tcp.h utils_cmd.h parse_ini.h extra_opts.h
 
 if USE_PARSE_INI
diff --git a/lib/maxfd.c b/lib/maxfd.c
new file mode 100644
index 0000000..529b356
--- /dev/null
+++ b/lib/maxfd.c
@@ -0,0 +1,26 @@
+#include "./maxfd.h"
+#include <errno.h>
+
+long mp_open_max (void) {
+        long maxfd = 0L;
+        /* Try sysconf(_SC_OPEN_MAX) first, as it can be higher than OPEN_MAX.
+         * If that fails and the macro isn't defined, we fall back to an educated
+         * guess. There's no guarantee that our guess is adequate and the program
+         * will die with SIGSEGV if it isn't and the upper boundary is breached. */
+
+#ifdef _SC_OPEN_MAX
+        errno = 0;
+        if ((maxfd = sysconf (_SC_OPEN_MAX)) < 0) {
+                if (errno == 0)
+                        maxfd = DEFAULT_MAXFD;   /* it's indeterminate */
+                else
+                        die (STATE_UNKNOWN, _("sysconf error for _SC_OPEN_MAX\n"));
+        }
+#elif defined(OPEN_MAX)
+        return OPEN_MAX
+#else   /* sysconf macro unavailable, so guess (may be wildly inaccurate) */
+        return DEFAULT_MAXFD;
+#endif
+
+        return(maxfd);
+}
diff --git a/lib/maxfd.h b/lib/maxfd.h
new file mode 100644
index 0000000..45218d0
--- /dev/null
+++ b/lib/maxfd.h
@@ -0,0 +1,9 @@
+#ifndef _MAXFD_
+#define _MAXFD_
+
+#define DEFAULT_MAXFD  256   /* fallback value if no max open files value is set */
+#define MAXFD_LIMIT   8192   /* upper limit of open files */
+
+long mp_open_max (void);
+
+#endif // _MAXFD_
diff --git a/lib/utils_cmd.c b/lib/utils_cmd.c
index 883f1ec..f66fd57 100644
--- a/lib/utils_cmd.c
+++ b/lib/utils_cmd.c
@@ -53,6 +53,9 @@
 static pid_t *_cmd_pids = NULL;
 
 #include "utils_base.h"
+
+#include "./maxfd.h"
+
 #include <fcntl.h>
 
 #ifdef HAVE_SYS_WAIT_H
@@ -96,13 +99,7 @@ extern void die (int, const char *, ...)
 void
 cmd_init (void)
 {
-#ifndef maxfd
-        if (!maxfd && (maxfd = sysconf (_SC_OPEN_MAX)) < 0) {
-                /* possibly log or emit a warning here, since there's no
-                 * guarantee that our guess at maxfd will be adequate */
-                maxfd = DEFAULT_MAXFD;
-        }
-#endif
+        long maxfd = mp_open_max();
 
         /* if maxfd is unnaturally high, we force it to a lower value
          * ( e.g. on SunOS, when ulimit is set to unlimited: 2147483647 this would cause
@@ -158,6 +155,7 @@ _cmd_open (char *const *argv, int *pfd, int *pfderr)
                 /* close all descriptors in _cmd_pids[]
                  * This is executed in a separate address space (pure child),
                  * so we don't have to worry about async safety */
+                long maxfd = mp_open_max();
                 for (i = 0; i < maxfd; i++)
                         if (_cmd_pids[i] > 0)
                                 close (i);
@@ -184,6 +182,7 @@ _cmd_close (int fd)
         pid_t pid;
 
         /* make sure the provided fd was opened */
+        long maxfd = mp_open_max();
         if (fd < 0 || fd > maxfd || !_cmd_pids || (pid = _cmd_pids[fd]) == 0)
                 return -1;
 
@@ -275,7 +274,6 @@ _cmd_fetch_output (int fd, output * op, int flags)
 int
 cmd_run (const char *cmdstring, output * out, output * err, int flags)
 {
-        int fd, pfd_out[2], pfd_err[2];
         int i = 0, argc;
         size_t cmdlen;
         char **argv = NULL;
@@ -397,6 +395,7 @@ timeout_alarm_handler (int signo)
                 printf (_("%s - Plugin timed out after %d seconds\n"),
                                                 state_text(timeout_state), timeout_interval);
 
+                long maxfd = mp_open_max();
                 if(_cmd_pids) for(i = 0; i < maxfd; i++) {
                         if(_cmd_pids[i] != 0) kill(_cmd_pids[i], SIGKILL);
                 }