ipl_tools: Change buffer size and copy strings correctly

Change the buffer size to what we actually need and use util_strlcpy()
to correctly copy strings.

This gets rid of the following GCC8 compile warnings:

fcp.c: In function ‘fcp_wwpn_get’:
fcp.c:44:2: warning: ‘strncpy’ output may be truncated copying 20 bytes
from a string of length 4095 [-Wstringop-truncation]
  strncpy(wwpn, buf, 20);
  ^~~~~~~~~~~~~~~~~~~~~~
fcp.c: In function ‘fcp_lun_get’:
fcp.c:65:2: warning: ‘strncpy’ output may be truncated copying 20 bytes
from a string of length 4095 [-Wstringop-truncation]
  strncpy(lun, buf, 20);
  ^~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

ipl_tools/fcp.c

@@ -9,6 +9,7 @@
  * it under the terms of the MIT license. See LICENSE for details.
  */
 
+#include "lib/util_libc.h"
 #include "ipl_tools.h"
 
 /*
@@ -30,7 +31,7 @@ int fcp_is_device(const char *devno)
  */
 void fcp_wwpn_get(const char *device, char *wwpn)
 {
-	char path[PATH_MAX], buf[4096];
+	char path[PATH_MAX], buf[20];
 	FILE *fh;
 	int rc;
 
@@ -41,7 +42,7 @@ void fcp_wwpn_get(const char *device, char *wwpn)
 	rc = fscanf(fh, "%s", buf);
 	if (rc <= 0)
 		ERR_EXIT("Could not lookup WWPN \"%s\"", path);
-	strncpy(wwpn, buf, 20);
+	util_strlcpy(wwpn, buf, 20);
 	fclose(fh);
 }
 
@@ -51,7 +52,7 @@ void fcp_wwpn_get(const char *device, char *wwpn)
  */
 void fcp_lun_get(const char *device, char *lun)
 {
-	char path[PATH_MAX], buf[4096];
+	char path[PATH_MAX], buf[20];
 	FILE *fh;
 	int rc;
 
@@ -62,7 +63,7 @@ void fcp_lun_get(const char *device, char *lun)
 	rc = fscanf(fh, "%s", buf);
 	if (rc <= 0)
 		ERR_EXIT("Could not lookup LUN \"%s\"", path);
-	strncpy(lun, buf, 20);
+	util_strlcpy(lun, buf, 20);
 	fclose(fh);
 }