[monitoring-plugins] fix maxfd being zero

[Sven Nierlein]

    Module: monitoring-plugins
    Branch: master
    Commit: e8325b39c47e6fbf7c8c1e31f9026870d9520af5
    Author: Sven Nierlein <sven at nierlein.de>
 Committer: Sven Nierlein <sven at nierlein.org>
      Date: Thu Apr 25 13:03:10 2019 +0200
       URL: https://www.monitoring-plugins.org/repositories/monitoring-plugins/commit/?id=e8325b3

fix maxfd being zero

If _SC_OPEN_MAX is available then maxfd was zero initialized and never set to the value from sysconf.
This leads to segfaults with free(): invalid size introduced by commit 7cafb0e84550035fe671662c293122be975065ca.

Signed-off-by: Sven Nierlein <sven at nierlein.de>

---

 plugins/popen.c  | 52 +++-------------------------------------------------
 plugins/runcmd.c | 10 ++--------
 plugins/utils.c  | 16 ++++++++++++++++
 plugins/utils.h  |  2 ++
 4 files changed, 23 insertions(+), 57 deletions(-)

diff --git a/plugins/popen.c b/plugins/popen.c
index 116d168..557fb44 100644
--- a/plugins/popen.c
+++ b/plugins/popen.c
@@ -78,14 +78,9 @@ RETSIGTYPE popen_timeout_alarm_handler (int);
 
 #define	min(a,b)	((a) < (b) ? (a) : (b))
 #define	max(a,b)	((a) > (b) ? (a) : (b))
-static void err_sys (const char *, ...) __attribute__((noreturn,format(printf, 1, 2)));
-char *rtrim (char *, const char *);
 
 char *pname = NULL;							/* caller can set this from argv[0] */
 
-/*int *childerr = NULL;*//* ptr to array allocated at run-time */
-/*extern pid_t *childpid = NULL; *//* ptr to array allocated at run-time */
-
 #ifdef REDHAT_SPOPEN_ERROR
 static volatile int childtermd = 0;
 #endif
@@ -184,6 +179,9 @@ spopen (const char *cmdstring)
 	}
 	argv[i] = NULL;
 
+	if(maxfd == 0)
+		maxfd = open_max();
+
 	if (childpid == NULL) {				/* first time through */
 		if ((childpid = calloc ((size_t)maxfd, sizeof (pid_t))) == NULL)
 			return (NULL);
@@ -296,47 +294,3 @@ popen_timeout_alarm_handler (int signo)
 		exit (STATE_CRITICAL);
 	}
 }
-
-
-/* Fatal error related to a system call.
- * Print a message and die. */
-
-#define MAXLINE 2048
-static void
-err_sys (const char *fmt, ...)
-{
-	int errnoflag = 1;
-	int errno_save;
-	char buf[MAXLINE];
-
-	va_list ap;
-
-	va_start (ap, fmt);
-	/* err_doit (1, fmt, ap); */
-	errno_save = errno;						/* value caller might want printed */
-	vsprintf (buf, fmt, ap);
-	if (errnoflag)
-		sprintf (buf + strlen (buf), ": %s", strerror (errno_save));
-	strcat (buf, "\n");
-	fflush (stdout);							/* in case stdout and stderr are the same */
-	fputs (buf, stderr);
-	fflush (NULL);								/* flushes all stdio output streams */
-	va_end (ap);
-	exit (1);
-}
-
-char *
-rtrim (char *str, const char *tok)
-{
-	int i = 0;
-	int j = sizeof (str);
-
-	while (str != NULL && i < j) {
-		if (*(str + i) == *tok) {
-			sprintf (str + i, "%s", "\0");
-			return str;
-		}
-		i++;
-	}
-	return str;
-}
diff --git a/plugins/runcmd.c b/plugins/runcmd.c
index c382867..a7155d2 100644
--- a/plugins/runcmd.c
+++ b/plugins/runcmd.c
@@ -86,14 +86,8 @@ extern void die (int, const char *, ...)
  * through this api and thus achieve async-safeness throughout the api */
 void np_runcmd_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 = 256;
-	}
-#endif
-
+	if(maxfd == 0)
+		maxfd = open_max();
 	if(!np_pids) np_pids = calloc(maxfd, sizeof(pid_t));
 }
 
diff --git a/plugins/utils.c b/plugins/utils.c
index ee62013..348ec02 100644
--- a/plugins/utils.c
+++ b/plugins/utils.c
@@ -678,3 +678,19 @@ 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);
+}
diff --git a/plugins/utils.h b/plugins/utils.h
index 6aa316f..33a2054 100644
--- a/plugins/utils.h
+++ b/plugins/utils.h
@@ -97,6 +97,8 @@ 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 */