From: Florian Forster <octo@collectd.org>
Date: Mon, 8 Sep 2014 15:07:39 +0000 (+0200)
Subject: processes plugin: Limit the buffer size used for command line matching.
X-Git-Tag: collectd-5.5.0~205
X-Git-Url: https://git.octo.it/?a=commitdiff_plain;h=c0a9b7b38edf881e134f602b62990518a79bf191;p=collectd.git

processes plugin: Limit the buffer size used for command line matching.

ARG_MAX is quite big on many systems, for example >100 kByte on
GNU/Linux. This is a problem for systems with tight memory constraints,
for example embedded devices.

This patch uses at most 4 kByte for this, which out to be enough for the
vast majority of users. Users with specific requirements can compile
with "CMDLINE_BUFFER_SIZE=${LOTS}" in their CPPFLAGS to override this
default.

Fixes: #652
---

diff --git a/src/processes.c b/src/processes.c
index 5601d290..aa47f332 100644
--- a/src/processes.c
+++ b/src/processes.c
@@ -128,8 +128,12 @@
 # include <kstat.h>
 #endif
 
-#ifndef ARG_MAX
-#  define ARG_MAX 4096
+#ifndef CMDLINE_BUFFER_SIZE
+# if defined(ARG_MAX) && (ARG_MAX < 4096)
+#  define CMDLINE_BUFFER_SIZE ARG_MAX
+# else
+#  define CMDLINE_BUFFER_SIZE 4096
+# endif
 #endif
 
 typedef struct procstat_entry_s
@@ -1686,7 +1690,7 @@ static int ps_read (void)
 	DIR           *proc;
 	int            pid;
 
-	char cmdline[ARG_MAX];
+	char cmdline[CMDLINE_BUFFER_SIZE];
 
 	int        status;
 	procstat_t ps;
@@ -1824,7 +1828,7 @@ static int ps_read (void)
 		 * filter out threads (duplicate PID entries). */
 		if ((proc_ptr == NULL) || (proc_ptr->ki_pid != procs[i].ki_pid))
 		{
-			char cmdline[ARG_MAX] = "";
+			char cmdline[CMDLINE_BUFFER_SIZE] = "";
 			_Bool have_cmdline = 0;
 
 			proc_ptr = &(procs[i]);