Allow chardev of type 'file' for UML domains.

Like the comment suggested, we just open the file and pass the file
descriptor to uml. The input "stream" is set to "null", since I couldn't
find any useful way to actually use a file for input for a chardev and
this also mimics what e.g. QEmu does internally.
Signed-off-by: NSoren Hansen <soren@linux2go.dk>

src/uml/uml_conf.c

@@ -295,7 +295,8 @@ error:
 
 static char *
 umlBuildCommandLineChr(virDomainChrDefPtr def,
-                       const char *dev)
+                       const char *dev,
+                       fd_set *keepfd)
 {
     char *ret = NULL;
 
@@ -344,8 +345,27 @@ umlBuildCommandLineChr(virDomainChrDefPtr def,
         break;
 
     case VIR_DOMAIN_CHR_TYPE_FILE:
-    case VIR_DOMAIN_CHR_TYPE_PIPE:
-        /* XXX could open the file/pipe & just pass the FDs */
+         {
+            int fd_out;
+
+            if ((fd_out = open(def->data.file.path,
+                               O_WRONLY | O_APPEND | O_CREAT, 0660)) < 0) {
+                virReportSystemError(errno,
+                                     _("failed to open chardev file: %s"),
+                                     def->data.file.path);
+                return NULL;
+            }
+            if (virAsprintf(&ret, "%s%d=null,fd:%d", dev, def->target.port, fd_out) < 0) {
+                virReportOOMError();
+                close(fd_out);
+                return NULL;
+            }
+            FD_SET(fd_out, keepfd);
+        }
+        break;
+   case VIR_DOMAIN_CHR_TYPE_PIPE:
+        /* XXX could open the pipe & just pass the FDs. Be wary of
+         * the effects of blocking I/O, though. */
 
     case VIR_DOMAIN_CHR_TYPE_VC:
     case VIR_DOMAIN_CHR_TYPE_UDP:
@@ -391,6 +411,7 @@ static char *umlNextArg(char *args)
 int umlBuildCommandLine(virConnectPtr conn,
                         struct uml_driver *driver ATTRIBUTE_UNUSED,
                         virDomainObjPtr vm,
+                        fd_set *keepfd,
                         const char ***retargv,
                         const char ***retenv)
 {
@@ -513,7 +534,7 @@ int umlBuildCommandLine(virConnectPtr conn,
     for (i = 0 ; i < UML_MAX_CHAR_DEVICE ; i++) {
         char *ret = NULL;
         if (i == 0 && vm->def->console)
-            ret = umlBuildCommandLineChr(vm->def->console, "con");
+            ret = umlBuildCommandLineChr(vm->def->console, "con", keepfd);
         if (!ret)
             if (virAsprintf(&ret, "con%d=none", i) < 0)
                 goto no_memory;
@@ -527,7 +548,7 @@ int umlBuildCommandLine(virConnectPtr conn,
             if (vm->def->serials[j]->target.port == i)
                 chr = vm->def->serials[j];
         if (chr)
-            ret = umlBuildCommandLineChr(chr, "ssl");
+            ret = umlBuildCommandLineChr(chr, "ssl", keepfd);
         if (!ret)
             if (virAsprintf(&ret, "ssl%d=none", i) < 0)
                 goto no_memory;

src/uml/uml_conf.h

@@ -71,6 +71,7 @@ virCapsPtr  umlCapsInit               (void);
 int         umlBuildCommandLine       (virConnectPtr conn,
                                        struct uml_driver *driver,
                                        virDomainObjPtr dom,
+                                       fd_set *keepfd,
                                        const char ***retargv,
                                        const char ***retenv);
 

src/uml/uml_driver.c

@@ -869,7 +869,7 @@ static int umlStartVMDaemon(virConnectPtr conn,
         return -1;
     }
 
-    if (umlBuildCommandLine(conn, driver, vm,
+    if (umlBuildCommandLine(conn, driver, vm, &keepfd,
                             &argv, &progenv) < 0) {
         close(logfd);
         umlCleanupTapDevices(conn, vm);
@@ -908,6 +908,14 @@ static int umlStartVMDaemon(virConnectPtr conn,
                            NULL, NULL, NULL);
     close(logfd);
 
+    /*
+     * At the moment, the only thing that populates keepfd is
+     * umlBuildCommandLineChr. We want to close every fd it opens.
+     */
+    for (i = 0; i < FD_SETSIZE; i++)
+        if (FD_ISSET(i, &keepfd))
+            close(i);
+
     for (i = 0 ; argv[i] ; i++)
         VIR_FREE(argv[i]);
     VIR_FREE(argv);