Rework maxfd/open_max to avoid unused variables

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

lib/utils_cmd.c

@@ -43,6 +43,9 @@
 #include "utils.h"
 #include "utils_cmd.h"
 #include "utils_base.h"
+
+#include "./maxfd.h"
+
 #include <fcntl.h>
 
 #ifdef HAVE_SYS_WAIT_H
@@ -86,13 +89,7 @@ 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 = 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
@@ -148,6 +145,7 @@ _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 = open_max();
 		for (i = 0; i < maxfd; i++)
 			if (_cmd_pids[i] > 0)
 				close (i);
@@ -174,6 +172,7 @@ _cmd_close (int fd)
 	pid_t pid;
 
 	/* make sure the provided fd was opened */
+	long maxfd = open_max();
 	if (fd < 0 || fd > maxfd || !_cmd_pids || (pid = _cmd_pids[fd]) == 0)
 		return -1;
 
@@ -265,7 +264,6 @@ _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;
@@ -387,6 +385,7 @@ timeout_alarm_handler (int signo)
 		printf (_("%s - Plugin timed out after %d seconds\n"),
 						state_text(timeout_state), timeout_interval);
 
+		long maxfd = open_max();
 		if(_cmd_pids) for(i = 0; i < maxfd; i++) {
 			if(_cmd_pids[i] != 0) kill(_cmd_pids[i], SIGKILL);
 		}

plugins/common.h

@@ -225,18 +225,4 @@ enum {
 # define __attribute__(x) /* do nothing */
 #endif
 
-/* 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. */
-#define DEFAULT_MAXFD  256   /* fallback value if no max open files value is set */
-#define MAXFD_LIMIT   8192   /* upper limit of open files */
-#ifdef _SC_OPEN_MAX
-static long maxfd = 0;
-#elif defined(OPEN_MAX)
-# define maxfd OPEN_MAX
-#else	/* sysconf macro unavailable, so guess (may be wildly inaccurate) */
-# define maxfd DEFAULT_MAXFD
-#endif
-
 #endif /* _COMMON_H_ */

plugins/popen.c

@@ -38,8 +38,9 @@
 * 
 *****************************************************************************/
 
-#include "common.h"
-#include "utils.h"
+#include "./common.h"
+#include "./utils.h"
+#include "../lib/maxfd.h"
 
 /* extern so plugin has pid to kill exec'd process on timeouts */
 extern pid_t *childpid;
@@ -177,8 +178,7 @@ spopen (const char *cmdstring)
 	}
 	argv[i] = NULL;
 
-	if(maxfd == 0)
-		maxfd = open_max();
+	long maxfd = open_max();
 
 	if (childpid == NULL) {				/* first time through */
 		if ((childpid = calloc ((size_t)maxfd, sizeof (pid_t))) == NULL)

plugins/runcmd.c

@@ -88,8 +88,7 @@ extern void die (int, const char *, ...)
  * through this api and thus achieve async-safeness throughout the api */
 void np_runcmd_init(void)
 {
-	if(maxfd == 0)
-		maxfd = open_max();
+  long maxfd = open_max();
 	if(!np_pids) np_pids = calloc(maxfd, sizeof(pid_t));
 }
 
@@ -192,6 +191,7 @@ np_runcmd_open(const char *cmdstring, int *pfd, int *pfderr)
 		/* close all descriptors in np_pids[]
 		 * This is executed in a separate address space (pure child),
 		 * so we don't have to worry about async safety */
+    long maxfd = open_max();
 		for (i = 0; i < maxfd; i++)
 			if(np_pids[i] > 0)
 				close (i);
@@ -219,6 +219,7 @@ np_runcmd_close(int fd)
 	pid_t pid;
 
 	/* make sure this fd was opened by popen() */
+  long maxfd = open_max();
 	if(fd < 0 || fd > maxfd || !np_pids || (pid = np_pids[fd]) == 0)
 		return -1;
 
@@ -242,6 +243,7 @@ runcmd_timeout_alarm_handler (int signo)
 	if (signo == SIGALRM)
 		puts(_("CRITICAL - Plugin timed out while executing system call"));
 
+  long maxfd = open_max();
 	if(np_pids) for(i = 0; i < maxfd; i++) {
 		if(np_pids[i] != 0) kill(np_pids[i], SIGKILL);
 	}

plugins/utils.c

@@ -804,19 +804,3 @@ char *sperfdata_int (const char *label,
 
 	return data;
 }
-
-int
-open_max (void)
-{
-	errno = 0;
-	if (maxfd > 0)
-		return(maxfd);
-
-	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"));
-	}
-	return(maxfd);
-}

plugins/utils.h

@@ -106,8 +106,6 @@ char *sperfdata (const char *, double, const char *, char *, char *,
 char *sperfdata_int (const char *, int, const char *, char *, char *,
                      int, int, int, int);
 
-int open_max (void);
-
 /* The idea here is that, although not every plugin will use all of these, 
    most will or should.  Therefore, for consistency, these very common 
    options should have only these meanings throughout the overall suite */