Initial s390-tools-2.0.0 import

This commit is based on the s390-tools-1.39.0 version.

Changes on top of s390-tools-1.39.0:

 - Add MIT license to all source files
 - Add LICENSE file
 - Transform REAMDE to README.md (markdown)
 - Add AUTHORS.md file
 - Add CONTRIBUTING.md file
 - Move changelog from README to CHANGELOG.md file

Reviewed-by: Stefan Haberland <sth@linux.vnet.ibm.com>
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>

zdev/src/iscsi.c

@@ -0,0 +1,110 @@
+/*
+ * zdev - Modify and display the persistent configuration of devices
+ *
+ * Copyright IBM Corp. 2016, 2017
+ *
+ * s390-tools is free software; you can redistribute it and/or modify
+ * it under the terms of the MIT license. See LICENSE for details.
+ */
+
+#include <ctype.h>
+#include <string.h>
+
+#include "devnode.h"
+#include "iscsi.h"
+#include "misc.h"
+#include "path.h"
+
+/* Retrieve the IP address of the iSCSI initiator networking portal associated
+ * with block device @blkdev. */
+static char *ip_from_blockdev(struct devnode *blkdev)
+{
+	char *link, *curr, *end, *path = NULL, *ip = NULL;
+
+	link = devnode_readlink(blkdev);
+	if (!link)
+		return NULL;
+
+	/* ../../devices/platform/host0/session1/target0:0:0/0:0:0:1/... */
+	curr = strstr(link, "/devices/");
+	if (!curr)
+		goto out;
+	curr++;
+
+	/* curr=devices/platform/host0/session1/target0:0:0/0:0:0:1/... */
+	end = strstr(curr, "/session");
+	if (!end)
+		goto out;
+	*end = 0;
+
+	/* curr=devices/platform/host0 */
+	end = strstr(curr, "/host");
+	if (!end)
+		goto out;
+	end++;
+
+	/* curr=devices/platform/host0
+	 * end=host0 */
+	path = path_get("/sys/%s/iscsi_host/%s/ipaddress", curr, end);
+	ip = misc_read_text_file(path, 0, err_ignore);
+
+out:
+	free(path);
+	free(link);
+
+	return ip;
+}
+
+static struct devnode *netdev_from_ip(char *ip)
+{
+	char *cmd, *text, *dev, *end;
+	struct devnode *devnode = NULL;
+
+	cmd = misc_asprintf("%s -o address show to %s 2>/dev/null", PATH_IP,
+			    ip);
+	text = misc_read_cmd_output(cmd, 0, err_ignore);
+	if (!text)
+		goto out;
+
+	/* text=2: enccw0.0.f5f0    inet ... */
+	for (dev = text; *dev && !isspace(*dev); dev++);
+
+	/* dev= enccw0.0.f5f0    inet ... */
+	for (; isspace(*dev); dev++);
+
+	/* dev=enccw0.0.f5f0    inet ... */
+	for (end = dev; *end && !isspace(*end); end++);
+	if (end == dev)
+		goto out;
+	*end = 0;
+
+	/* dev=enccw0.0.f5f0 */
+	devnode = devnode_new(NETDEV, 0, 0, dev);
+
+out:
+	free(cmd);
+	free(text);
+
+	return devnode;
+}
+
+/* Retrieve the networking device devnode that provides the specified
+ * iSCSI block device @blkdev. */
+struct devnode *iscsi_get_net_devnode(struct devnode *blkdev)
+{
+	struct devnode *devnode = NULL;
+	char *ip;
+
+	if (blkdev->type != BLOCKDEV)
+		return NULL;
+
+	ip = ip_from_blockdev(blkdev);
+	if (!ip)
+		return NULL;
+
+	devnode = netdev_from_ip(ip);
+
+	free(ip);
+
+	return devnode;
+}