[PATCH LIBVIRT v2] libxl: Support cmdline= in xl config files

[Ian Campbell <ian.campbell@citrix.com>]

... and consolidate the cmdline/extra/root parsing to facilitate doing
so.

The logic is the same as xl's parse_cmdline from the current xen.git master
branch (e6f0e099d2c17de47fd86e817b1998db903cab61).

In order to introduce a use of VIR_WARN for logging I had to add
virerror.h and VIR_LOG_INIT.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
---
NB: I was unsure if I was supposed to change VIR_FROM_NONE into
VIR_FROM_XEN, so I didn't (but will on advice).

v2: Use VIR_INFO (adding necessary infra)
    Don't initialise things to NULL when there is no need.
---
 src/xenconfig/xen_xl.c | 66 +++++++++++++++++++++++++++++++-------------------
 1 file changed, 41 insertions(+), 25 deletions(-)

diff --git a/src/xenconfig/xen_xl.c b/src/xenconfig/xen_xl.c
index 91cdff6..3d820cc 100644
--- a/src/xenconfig/xen_xl.c
+++ b/src/xenconfig/xen_xl.c
@@ -27,6 +27,7 @@
 
 #include "virconf.h"
 #include "virerror.h"
+#include "virlog.h"
 #include "domain_conf.h"
 #include "viralloc.h"
 #include "virstring.h"
@@ -35,6 +36,8 @@
 
 #define VIR_FROM_THIS VIR_FROM_NONE
 
+VIR_LOG_INIT("xen.xen_xl");
+
 /*
  * Xen provides a libxl utility library, with several useful functions,
  * specifically xlu_disk_parse for parsing xl disk config strings.
@@ -58,11 +61,46 @@ extern int xlu_disk_parse(XLU_Config *cfg,
                           libxl_device_disk *disk);
 #endif
 
+static int xenParseCmdline(virConfPtr conf, char **r_cmdline)
+{
+    char *cmdline;
+    const char *root, *extra, *buf;
+
+    if (xenConfigGetString(conf, "cmdline", &buf, NULL) < 0)
+        return -1;
+
+    if (xenConfigGetString(conf, "root", &root, NULL) < 0)
+        return -1;
+
+    if (xenConfigGetString(conf, "extra", &extra, NULL) < 0)
+        return -1;
+
+    if (buf) {
+        if (VIR_STRDUP(cmdline, buf) < 0)
+            return -1;
+        if (root || extra)
+            VIR_WARN("ignoring root= and extra= in favour of cmdline=");
+    } else {
+        if (root && extra) {
+            if (virAsprintf(&cmdline, "root=%s %s", root, extra) < 0)
+                return -1;
+        } else if (root) {
+            if (virAsprintf(&cmdline, "root=%s", root) < 0)
+                return -1;
+        } else if (extra) {
+            if (VIR_STRDUP(cmdline, extra) < 0)
+                return -1;
+        }
+    }
+
+    *r_cmdline = cmdline;
+    return 0;
+}
+
 static int
 xenParseXLOS(virConfPtr conf, virDomainDefPtr def, virCapsPtr caps)
 {
     size_t i;
-    const char *extra, *root;
 
     if (def->os.type == VIR_DOMAIN_OSTYPE_HVM) {
         const char *boot;
@@ -84,19 +122,8 @@ xenParseXLOS(virConfPtr conf, virDomainDefPtr def, virCapsPtr caps)
         if (xenConfigCopyStringOpt(conf, "ramdisk", &def->os.initrd) < 0)
             return -1;
 
-        if (xenConfigGetString(conf, "extra", &extra, NULL) < 0)
-            return -1;
-
-        if (xenConfigGetString(conf, "root", &root, NULL) < 0)
+        if (xenParseCmdline(conf, &def->os.cmdline) < 0)
             return -1;
-
-        if (root) {
-            if (virAsprintf(&def->os.cmdline, "root=%s %s", root, extra) < 0)
-                return -1;
-        } else {
-            if (VIR_STRDUP(def->os.cmdline, extra) < 0)
-                return -1;
-        }
 #endif
 
         if (xenConfigGetString(conf, "boot", &boot, "c") < 0)
@@ -132,19 +159,8 @@ xenParseXLOS(virConfPtr conf, virDomainDefPtr def, virCapsPtr caps)
         if (xenConfigCopyStringOpt(conf, "ramdisk", &def->os.initrd) < 0)
             return -1;
 
-        if (xenConfigGetString(conf, "extra", &extra, NULL) < 0)
-            return -1;
-
-        if (xenConfigGetString(conf, "root", &root, NULL) < 0)
+        if (xenParseCmdline(conf, &def->os.cmdline) < 0)
             return -1;
-
-        if (root) {
-            if (virAsprintf(&def->os.cmdline, "root=%s %s", root, extra) < 0)
-                return -1;
-        } else {
-            if (VIR_STRDUP(def->os.cmdline, extra) < 0)
-                return -1;
-        }
     }
 
     return 0;
-- 
2.1.4