1 files changed, 139 insertions, 0 deletions
diff --git a/src/lpj.c b/src/lpj.c
new file mode 100644
index 00000000..9c1acce9
--- /dev/null
+++ b/src/lpj.c
@@ -0,0 +1,139 @@
+/* libguestfs
+ * Copyright (C) 2012 Red Hat Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+
+#include "glthread/lock.h"
+
+#include "guestfs.h"
+#include "guestfs-internal.h"
+
+/* Calculate host kernel loops_per_jiffy, so that this can be passed
+ * to TCG guests (only) using the lpj= kernel parameter, which avoids
+ * have to compute this at kernel boot time in a VM.
+ *
+ * Currently this is only available in the boot messages, but I have
+ * posted a patch asking for this to be added to /proc/cpuinfo too.
+ *
+ * Notes:
+ * - We only try to calculate lpj once.
+ * - Trying to calculate lpj must not fail.  If the return value is
+ *   <= 0, it is ignored by the caller.
+ *
+ * (Suggested by Marcelo Tosatti)
+ */
+
+gl_lock_define_initialized (static, lpj_lock);
+static int lpj = 0;
+static int read_lpj_from_var_log_dmesg (guestfs_h *g);
+static int read_lpj_from_dmesg (guestfs_h *g);
+static int read_lpj_common (guestfs_h *g, const char *func, const char *command);
+
+int
+guestfs___get_lpj (guestfs_h *g)
+{
+  int r;
+
+  gl_lock_lock (lpj_lock);
+  if (lpj != 0)
+    goto out;
+
+  /* Try reading lpj from these sources:
+   * - /proc/cpuinfo [in future]
+   * - dmesg
+   * - /var/log/dmesg
+   */
+  r = read_lpj_from_dmesg (g);
+  if (r > 0) {
+    lpj = r;
+    goto out;
+  }
+  lpj = read_lpj_from_var_log_dmesg (g);
+
+ out:
+  gl_lock_unlock (lpj_lock);
+  return lpj;
+}
+
+static int
+read_lpj_from_dmesg (guestfs_h *g)
+{
+  return read_lpj_common (g, __func__,
+                          "dmesg | grep -Eo 'lpj=[[:digit:]]+'");
+}
+
+static int
+read_lpj_from_var_log_dmesg (guestfs_h *g)
+{
+  return read_lpj_common (g, __func__,
+                          "grep -Eo 'lpj=[[:digit:]]+' /var/log/dmesg");
+}
+
+static void
+read_all (guestfs_h *g, void *retv, const char *buf, size_t len)
+{
+  char **ret = retv;
+
+  *ret = safe_strndup (g, buf, len);
+}
+
+static int
+read_lpj_common (guestfs_h *g, const char *func, const char *command)
+{
+  struct command *cmd;
+  int r;
+  char *buf = NULL;
+
+  cmd = guestfs___new_command (g);
+  guestfs___cmd_add_string_unquoted (cmd, command);
+  guestfs___cmd_set_stdout_callback (cmd, read_all, &buf,
+                                     CMD_STDOUT_FLAG_WHOLE_BUFFER);
+  r = guestfs___cmd_run (cmd);
+  guestfs___cmd_close (cmd);
+
+  if (r == -1 || !WIFEXITED (r) || WEXITSTATUS (r) != 0) {
+    debug (g, "%s: command failed with code %d: %s", func, r, command);
+    free (buf);
+    return -1;
+  }
+
+  if (buf == NULL) {
+    debug (g, "%s: callback not called", func);
+    return -1;
+  }
+
+  if (strlen (buf) < 4 || sscanf (&buf[4], "%d", &r) != 1) {
+    debug (g, "%s: invalid buffer returned by grep: %s", func, buf);
+    free (buf);
+    return -1;
+  }
+
+  free (buf);
+
+  debug (g, "%s: calculated lpj=%d", func, r);
+
+  return r;
+}