[PATCH] [v3] libxl: Add API to retrieve domain console tty

[Bamvor Jian Zhang <bjzhang@suse.com>]

This api retrieve domain console from xenstore. With this new api, it is easy to implement "virsh console" command in libvirt libxl driver.

Signed-off-by: Bamvor Jian Zhang <bjzhang@suse.com>

Changes since v2:
 * using ERROR_INVAL instead of ERROR_FAIL in libxl_console_get_tty and
 libxl__primary_console_find if need.
 * remove _out from some value name in libxl_primary_console_exec
 * add error handler and log message in libxl_console_get_tty.
 BUT, NOT update strdup to libxl__strdup. bacause libxl__strdup(0, tty) will lead to null pointer access in CTX maco.
 * add empty line between my comment and other function.

diff -r d7318231cfe3 -r 3496f86000b8 tools/libxl/libxl.c
--- a/tools/libxl/libxl.c	Thu May 31 10:18:52 2012 +0200
+++ b/tools/libxl/libxl.c	Fri Jun 01 15:10:45 2012 +0800
@@ -1188,7 +1188,8 @@ out:
     return rc;
 }
 
-int libxl_console_exec(libxl_ctx *ctx, uint32_t domid, int cons_num, libxl_console_type type)
+int libxl_console_exec(libxl_ctx *ctx, uint32_t domid, int cons_num,
+                       libxl_console_type type)
 {
     GC_INIT(ctx);
     char *p = libxl__sprintf(gc, "%s/xenconsole", libxl__private_bindir_path());
@@ -1214,25 +1215,82 @@ out:
     return ERROR_FAIL;
 }
 
-int libxl_primary_console_exec(libxl_ctx *ctx, uint32_t domid_vm)
+int libxl_console_get_tty(libxl_ctx *ctx, uint32_t domid, int cons_num, 
+                          libxl_console_type type, char **path)
+{
+    GC_INIT(ctx);
+    char *dom_path = 0;
+    char *tty_path = 0;
+    char *tty = 0;
+    int rc;
+
+    dom_path = libxl__xs_get_dompath(gc, domid);
+    if (!dom_path) {
+        rc = ERROR_FAIL;
+        goto out;
+    }
+
+    switch (type) {
+    case LIBXL_CONSOLE_TYPE_SERIAL:
+        tty_path = GCSPRINTF("%s/serial/0/tty", dom_path);
+        break;
+    case LIBXL_CONSOLE_TYPE_PV:
+        if (cons_num == 0)
+            tty_path = GCSPRINTF("%s/console/tty", dom_path);
+        else
+            tty_path = GCSPRINTF("%s/device/console/%d/tty", dom_path, 
+                                cons_num);
+        break;
+    default:
+        rc = ERROR_INVAL;
+        goto out;
+    }
+
+    tty = libxl__xs_read(gc, XBT_NULL, tty_path);
+    if (!tty) {
+       LOGE(ERROR,"unable to read console tty path `%s'",tty_path);
+       rc = ERROR_FAIL;
+       goto out;
+    }
+
+    *path = strdup(tty);
+    if (!*path)
+        libxl__alloc_failed(CTX, __func__, strlen(*path), 1);
+
+    rc = 0;
+
+out:
+    GC_FREE;
+    return rc;
+}
+
+static int libxl__primary_console_find(libxl_ctx *ctx, uint32_t domid_vm, 
+                                       uint32_t *domid, int *cons_num, 
+                                       libxl_console_type *type)
 {
     GC_INIT(ctx);
     uint32_t stubdomid = libxl_get_stubdom_id(ctx, domid_vm);
-    int rc;
-    if (stubdomid)
-        rc = libxl_console_exec(ctx, stubdomid,
-                                STUBDOM_CONSOLE_SERIAL, LIBXL_CONSOLE_TYPE_PV);
-    else {
+    int rc = 0;
+
+    if (stubdomid) {
+        *domid = stubdomid;
+        *cons_num = STUBDOM_CONSOLE_SERIAL;
+        *type = LIBXL_CONSOLE_TYPE_PV;
+    } else {
         switch (libxl__domain_type(gc, domid_vm)) {
         case LIBXL_DOMAIN_TYPE_HVM:
-            rc = libxl_console_exec(ctx, domid_vm, 0, LIBXL_CONSOLE_TYPE_SERIAL);
+            *domid = domid_vm;
+            *cons_num = 0;
+            *type = LIBXL_CONSOLE_TYPE_SERIAL;
             break;
         case LIBXL_DOMAIN_TYPE_PV:
-            rc = libxl_console_exec(ctx, domid_vm, 0, LIBXL_CONSOLE_TYPE_PV);
+            *domid = domid_vm;
+            *cons_num = 0;
+            *type = LIBXL_CONSOLE_TYPE_PV;
             break;
         case -1:
-            LOG(ERROR,"unable to get domain type for domid=%"PRIu32,domid_vm);
-            rc = ERROR_FAIL;
+            LOG(ERROR,"unable to get domain type for domid=%"PRIu32, domid_vm);
+            rc = ERROR_INVAL;
             break;
         default:
             abort();
@@ -1242,6 +1300,31 @@ int libxl_primary_console_exec(libxl_ctx
     return rc;
 }
 
+int libxl_primary_console_exec(libxl_ctx *ctx, uint32_t domid_vm)
+{
+    uint32_t domid;
+    int cons_num;
+    libxl_console_type type;
+    int rc;
+
+    rc = libxl__primary_console_find(ctx, domid_vm, &domid, &cons_num, &type);
+    if ( rc ) return rc;
+    return libxl_console_exec(ctx, domid, cons_num, type);
+}
+
+int libxl_primary_console_get_tty(libxl_ctx *ctx, uint32_t domid_vm,
+                                  char **path)
+{
+    uint32_t domid;
+    int cons_num;
+    libxl_console_type type;
+    int rc;
+
+    rc = libxl__primary_console_find(ctx, domid_vm, &domid, &cons_num, &type);
+    if ( rc ) return rc;
+    return libxl_console_get_tty(ctx, domid, cons_num, type, path);
+}
+
 int libxl_vncviewer_exec(libxl_ctx *ctx, uint32_t domid, int autopass)
 {
     GC_INIT(ctx);
diff -r d7318231cfe3 -r 3496f86000b8 tools/libxl/libxl.h
--- a/tools/libxl/libxl.h	Thu May 31 10:18:52 2012 +0200
+++ b/tools/libxl/libxl.h	Fri Jun 01 15:10:45 2012 +0800
@@ -570,6 +570,18 @@ int libxl_console_exec(libxl_ctx *ctx, u
  * guests using pygrub. */
 int libxl_primary_console_exec(libxl_ctx *ctx, uint32_t domid_vm);
 
+/* libxl_console_get_tty retrieves the specified domain's console tty path
+ * and stores it in path. Caller is responsible for freeing the memory.
+ */
+int libxl_console_get_tty(libxl_ctx *ctx, uint32_t domid, int cons_num, 
+                          libxl_console_type type, char **path);
+
+/* libxl_primary_console_get_tty retrieves the specified domain's primary 
+ * console tty path and stores it in path. Caller is responsible for freeing
+ * the memory.
+ */
+int libxl_primary_console_get_tty(libxl_ctx *ctx, uint32_t domid_vm, char **path);
+
 /* May be called with info_r == NULL to check for domain's existance */
 int libxl_domain_info(libxl_ctx*, libxl_dominfo *info_r,
                       uint32_t domid);