Re: directing xm dmesg to syslog

[MINAI Katsuhito <minai@jp.fujitsu.com>]

[-- Attachment #1: Type: text/plain, Size: 1411 bytes --]

Hi all,

I made the logging daemon of the Xen message.
This daemon outputs the messege to syslog if messages were found
in the console ring by the polling every one second.

Following is the usage, but usually no option is necessary.
It will automatically be daemon.

usage: xenlogd [-h] [-k] [-r]
       -h: print help
       -k: kill alive logging daemon
       -r: restart logging daemon after kill alive one

Signed-off-by: Katsuhito Minai <minai@jp.fujitsu.com>

Best regards,
Katsuhito Minai



On Tue, 23 May 2006 16:31:44 +0100
Mark Williamson <mark.williamson@cl.cam.ac.uk> wrote:
> > short questin: I want to direct the oputput of xm dmesg in (near) realtime
> > to syslog.
> >
> > Is this possible?
> 
> dom0 Linux doesn't (currently) get any notifications that the xm dmesg output 
> has changed.
> 
> You could write a daemon to poll xm dmesg and send changes to syslog...  You 
> might like to consider having it clear the dmesg also, since it uses a 
> fixed-size buffer and won't work once that is full.
> 
> Cheers,
> Mark
> 
> -- 
> Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
> Mark: To answer a question with a question: What use is a skateboard?
> Dave: Skateboards have wheels.
> Mark: My wheel has a wheel!
> 
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users


[-- Attachment #2: xenlogd.patch --]
[-- Type: application/octet-stream, Size: 6425 bytes --]

diff -r 4f1e39ec05d6 tools/xenlogd/Makefile
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tools/xenlogd/Makefile	Fri Jun 09 15:40:36 2006 +0900
@@ -0,0 +1,7 @@
+CC=gcc
+CFLAGS=-lxenctrl
+
+xenlogd:
+
+clean:
+	rm -f xenlogd
diff -r 4f1e39ec05d6 tools/xenlogd/TODO
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tools/xenlogd/TODO	Fri Jun 09 15:40:36 2006 +0900
@@ -0,0 +1,9 @@
+
+Following is the usage, but usually no option is necessary.
+It will automatically be daemon.
+
+usage: xenlogd [-h] [-n] [-k] [-r]
+       -h: print help
+       -n: no daemonize
+       -k: kill alive logging daemon
+       -r: restart logging daemon after kill alive one
diff -r 4f1e39ec05d6 tools/xenlogd/xenlogd.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tools/xenlogd/xenlogd.c	Fri Jun 09 15:40:36 2006 +0900
@@ -0,0 +1,283 @@
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <syslog.h>
+#include <signal.h>
+#include <errno.h>
+#include <stdarg.h>
+#include <fcntl.h>
+#include <string.h>
+
+
+#define XCDSIZE (4096)
+#define XENHEAD "(XEN) "
+#define PIDFILE "/var/run/xenlogd.pid"
+#define STARTMSG "logging has been started."
+
+static char *cmdname;
+
+quit(int xc, char *fmt, ...)
+{
+  va_list ap;
+  
+  va_start(ap, fmt);
+  vsyslog(LOG_KERN|LOG_ALERT, fmt, ap);
+  va_end(ap);
+  exit(xc);
+}
+
+putsyslog(char *bp, int size)
+{
+  static char *prsvp = NULL;
+  static int prsvc = 0;
+  char *endp;
+  int offset;
+
+  if ((prsvp == NULL) && ((prsvp = malloc(XCDSIZE)) == NULL)) {
+    quit(1, "allocate buffer failed");
+  }
+
+  bp[size] = '\0';
+
+  for (endp = bp + size; bp < endp; bp++) {
+    if (*bp == '\n') {
+      prsvp[prsvc]  = '\0';
+      if ((strncmp(prsvp, XENHEAD, strlen(XENHEAD)) == 0)) {
+	offset = strlen(XENHEAD);
+      } else {
+	offset = 0;
+      }
+      syslog(LOG_KERN|LOG_ALERT, "%s", prsvp + offset);
+      prsvc = 0;
+    } else {
+      prsvp[prsvc] = *bp;
+      prsvc++;
+    }
+  }
+}
+
+static void child_exit(int sig)
+{
+  while (waitpid(-1, NULL, WNOHANG) > 0);
+}
+
+static void term_daemon(int sig)
+{
+  unlink(PIDFILE);
+  quit(0, "logging ended normally.");
+}
+
+void daemonize()
+{
+  pid_t pid;
+  int fd;
+  int len;
+  int i;
+  int pfd[2];
+  char buf[1024];
+  
+  if (getppid() == 1) {
+    return;
+  }
+
+  signal(SIGPIPE, SIG_IGN);
+
+  if (pipe(pfd) < 0) {
+    quit(1, "open pipe failed");
+  }
+
+  if ((pid = fork()) > 0) {
+    exit(0);
+  } 
+  if (pid < 0) {
+    quit(1, "fork failed: errno = %d", errno);
+  }
+  
+  setsid();
+  
+  if ((pid = fork()) > 0) {
+    exit(0);
+  } 
+  if (pid < 0) {
+    quit(1, "fork failed: errno = %d", errno);
+  }
+  
+  if ((fd = open("/dev/null",O_RDWR)) == -1) {
+    quit(1, "open /dev/null failed: errno = %d", errno);
+  }
+  
+  for (i = 0; i <= 2; i++) {
+    close(i);
+    dup2(fd, i);
+  }
+  
+  close(fd);
+  umask(027);
+
+  if (chdir("/") < 0) {
+    quit(1, "change to root dir failed: errno = %d", errno);
+  }
+
+  pid = getpid();
+  snprintf(buf, sizeof(buf), "%s.%d", PIDFILE, pid);
+  
+  fd = open(buf, O_RDWR | O_CREAT | O_EXCL);
+  if (fd < 0) {
+    quit(1, "open %s failed: errno = %d", buf, errno);
+  }
+
+  if (link(buf, PIDFILE) < 0) {
+    unlink(buf);
+    quit(1, "other logging daemon may keep alive");
+  }
+  unlink(buf);
+  
+  len = sprintf(buf, "%d\n", pid);
+  if (write(fd, buf, len) < 0) {
+    quit(1, "write %s failed: errno = %d", PIDFILE, errno);
+  }
+
+  signal(SIGCHLD, child_exit);
+  signal(SIGTSTP, SIG_IGN);
+  signal(SIGTTOU, SIG_IGN);
+  signal(SIGTTIN, SIG_IGN);
+  sigset(SIGTERM, term_daemon);
+
+  close(pfd[1]);
+  read(pfd[0], buf, sizeof(buf));
+  close(pfd[0]);
+}
+
+int kill_daemon()
+{
+  int fd, pid, len;
+  char buf[1024];
+  char *comm;
+
+  fd = open(PIDFILE, O_RDWR);
+  if (fd < 0) {
+    if (errno == ENOENT) {
+      fprintf(stderr,"%s: no other daemon exist\n", cmdname);
+    } else {
+      perror("open error: ");
+    }
+    return(1);
+  }
+  len = read(fd, buf, sizeof(buf));
+  if (len < 0) {
+    perror("read error: ");
+    return(1);
+  }
+  close(fd);
+  buf[len] = '\0';
+  pid = atoi(buf);
+  
+  if (pid) {
+    snprintf(buf, sizeof(buf), "/proc/%d/stat", pid);
+    if ((fd = open(buf, O_RDONLY)) >= 0) {
+      len = read(fd, buf, sizeof(buf));
+      strtok(buf, " ");
+      if (((comm = strtok(NULL, " ")) != NULL) 
+	  && (strcmp(comm, "(xenlogd)") == 0)) {
+	if (kill(pid, SIGTERM) < 0) {
+	  perror("kill error: ");
+	  return(1);
+	}
+	while (kill(pid, SIGTERM) == 0);
+	if (errno != ESRCH) {
+	  perror("kill error: ");
+	}
+      }
+    }
+  }
+  if ((fd = open(PIDFILE, O_RDWR)) >= 0) {
+    close(fd);
+    unlink(PIDFILE);
+    fprintf(stderr, "%s: lockfile existed but no daemon alive. it was deleted.\n", cmdname);
+  }
+}
+
+void usage()
+{
+  fprintf(stderr, "usage: %s [-h] [-n] [-k] [-r]\n", cmdname);
+  fprintf(stderr, "       -h: print help\n");
+  fprintf(stderr, "       -n: no daemonize\n");
+  fprintf(stderr, "       -k: kill alive logging daemon\n");
+  fprintf(stderr, "       -r: restart logging daemon after kill alive one\n");
+  exit(0);
+}
+
+
+main(int argc, char *argv[])
+{
+  int fd;
+  int rc;
+  int bufsize;
+  int opt;
+  char *bufaddr;
+  char *tmpp;
+  int no_daemonize = 0;
+  int kill_d = 0;
+  int restart_d = 0;
+
+  cmdname = argv[0];
+
+  while ((opt = getopt(argc, argv, "hnkr")) != -1) {
+    switch (opt) {
+    case 'h':
+    case '?':
+    default:
+      usage();
+      break;
+    case 'n':
+      no_daemonize = 1;
+      break;
+    case 'r':
+      restart_d = 1;
+      /* fall through */
+    case 'k':
+      kill_d = 1;
+      break;
+    }
+  }
+
+  openlog(XENHEAD, LOG_NDELAY|LOG_CONS, LOG_KERN);
+
+  fd = xc_interface_open();
+  if (fd < 0) {
+    quit(1, "failed to open xen interface");
+  }
+
+  if ((bufaddr = malloc(XCDSIZE)) ==NULL) {
+    quit(1, "allocate buffer failed");
+  }
+
+  if (kill_d) {
+    kill_daemon();
+    if (!restart_d) {
+      exit(0);
+    }
+  }
+
+  if (!no_daemonize) {
+    daemonize();
+  }
+  
+  syslog(LOG_KERN|LOG_ALERT, "logging has been started.");
+
+  for (;;) {
+    bufsize = XCDSIZE;
+
+    rc = xc_readconsolering(fd, &bufaddr, &bufsize, 1);
+    if (rc < 0) {
+      quit(1, "error: read console ring: %d: errno %d", rc, errno);
+    }
+
+    if (bufsize) {
+      putsyslog(bufaddr, bufsize);
+    }
+    sleep(1);
+  }
+}

[-- Attachment #3: Type: text/plain, Size: 137 bytes --]

_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users