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/* 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;
}
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