vpdupdate: Fixes syntax error bug on LE

From: Janani <jananive@linux.vnet.ibm.com>

[root@ltcbrazos2-lp12 home]# vpdupdate
sh: -c: line 1: syntax error: unexpected end of file

Some junk characters get introduced as parameters in the iprconfig command line.
This causes the unexpected end of file error. We clear out the string before
assigning it, in order to clear the junk.

Signed-off-by: Janani Venkataraman <jananive@linux.vnet.ibm.com>
---
 src/helper_functions.cpp |   14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/helper_functions.cpp b/src/helper_functions.cpp
index a9524f7..a46119d 100644
--- a/src/helper_functions.cpp
+++ b/src/helper_functions.cpp
@@ -28,9 +28,10 @@
 #include <cstdlib>
 #include <cstring>
 #include <fstream>
+#include <linux/limits.h>
 
 
-#define BUF_SIZE 512
+#define BUF_SIZE PATH_MAX
 
 using namespace std;
 using namespace lsvpd;
@@ -156,12 +157,13 @@ string HelperFunctions::parseString(const string& line, int str_pos, string& out
 	 */
 	string HelperFunctions::getSymLinkTarget(const string& symLinkPath)
 	{
-		char linkTarget[BUF_SIZE], *buf;
-		
+		char linkTarget[BUF_SIZE], *buf = NULL;
+		memset (linkTarget, 0, BUF_SIZE);
+
 		buf = strdup(symLinkPath.c_str());
-		int len = readlink(buf, linkTarget, sizeof(
-			linkTarget));
-		linkTarget[len] = '\0';
+		if (buf !=  NULL)
+			readlink(buf, linkTarget, BUF_SIZE - 1);
+
 		return string(getAbsolutePath(linkTarget, buf));
 	}