openvz: convert popen to virCommand

popen must be matched with pclose (not fclose), or it will leak
resources.  Furthermore, it is a lousy interface when it comes to
signal handling.  We're much better off using our decent command
wrapper.  Note that virCommand guarantees that VIR_FREE(outbuf) is
both required and safe to call, whether virCommandRun succeeded or
failed.

* src/openvz/openvz_conf.c (openvzLoadDomains, openvzGetVEID):
Replace popen with virCommand usage.

src/openvz/openvz_conf.c

@@ -51,6 +51,7 @@
 #include "util.h"
 #include "nodeinfo.h"
 #include "files.h"
+#include "command.h"
 
 #define VIR_FROM_THIS VIR_FROM_OPENVZ
 
@@ -433,26 +434,26 @@ openvzFreeDriver(struct openvz_driver *driver)
 
 
 int openvzLoadDomains(struct openvz_driver *driver) {
-    FILE *fp;
     int veid, ret;
     char status[16];
     char uuidstr[VIR_UUID_STRING_BUFLEN];
     virDomainObjPtr dom = NULL;
     char temp[50];
+    char *outbuf = NULL;
+    char *line;
+    virCommandPtr cmd = NULL;
 
     if (openvzAssignUUIDs() < 0)
         return -1;
 
-    if ((fp = popen(VZLIST " -a -ovpsid,status -H 2>/dev/null", "r")) == NULL) {
-        openvzError(VIR_ERR_INTERNAL_ERROR, "%s", _("popen failed"));
-        return -1;
-    }
-
-    while (!feof(fp)) {
-        if (fscanf(fp, "%d %s\n", &veid, status) != 2) {
-            if (feof(fp))
-                break;
+    cmd = virCommandNewArgList(VZLIST, "-a", "-ovpsid,status", "-H", NULL);
+    virCommandSetOutputBuffer(cmd, &outbuf);
+    if (virCommandRun(cmd, NULL) < 0)
+        goto cleanup;
 
+    line = *outbuf ? outbuf : NULL;
+    while (line) {
+        if (sscanf(line, "%d %s\n", &veid, status) != 2) {
             openvzError(VIR_ERR_INTERNAL_ERROR, "%s",
                         _("Failed to parse vzlist output"));
             goto cleanup;
@@ -526,9 +527,14 @@ int openvzLoadDomains(struct openvz_driver *driver) {
 
         virDomainObjUnlock(dom);
         dom = NULL;
+
+        line = strchr(line, '\n');
+        if (line)
+            line++;
     }
 
-    VIR_FORCE_FCLOSE(fp);
+    virCommandFree(cmd);
+    VIR_FREE(outbuf);
 
     return 0;
 
@@ -536,7 +542,8 @@ int openvzLoadDomains(struct openvz_driver *driver) {
     virReportOOMError();
 
  cleanup:
-    VIR_FORCE_FCLOSE(fp);
+    virCommandFree(cmd);
+    VIR_FREE(outbuf);
     if (dom)
         virDomainObjUnref(dom);
     return -1;
@@ -978,27 +985,23 @@ static int openvzAssignUUIDs(void)
  */
 
 int openvzGetVEID(const char *name) {
-    char *cmd;
+    virCommandPtr cmd;
+    char *outbuf;
     int veid;
-    FILE *fp;
     bool ok;
 
-    if (virAsprintf(&cmd, "%s %s -ovpsid -H", VZLIST, name) < 0) {
-        openvzError(VIR_ERR_INTERNAL_ERROR, "%s",
-                    _("virAsprintf failed"));
+    cmd = virCommandNewArgList(VZLIST, name, "-ovpsid", "-H", NULL);
+    virCommandSetOutputBuffer(cmd, &outbuf);
+    if (virCommandRun(cmd, NULL) < 0) {
+        virCommandFree(cmd);
+        VIR_FREE(outbuf);
         return -1;
     }
 
-    fp = popen(cmd, "r");
-    VIR_FREE(cmd);
-
-    if (fp == NULL) {
-        openvzError(VIR_ERR_INTERNAL_ERROR, "%s", _("popen failed"));
-        return -1;
-    }
+    virCommandFree(cmd);
+    ok = sscanf(outbuf, "%d\n", &veid) == 1;
+    VIR_FREE(outbuf);
 
-    ok = fscanf(fp, "%d\n", &veid ) == 1;
-    VIR_FORCE_FCLOSE(fp);
     if (ok && veid >= 0)
         return veid;