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vmd(8): disambiguate log messages per vm and device.

The logging output from vmd(8) often specifies the function performing
the logging, but leaves which vm or vm device to guesswork and
reading tea leaves.

Change the logging formatting to prefix with information about the
specific vm and potentially the device subprocess. Most of this
logging is behind the "verbose" mode, but for warnings this will
clarify which vm or device logged the warning.

The format of vm/<name>/<device><index> is chosen to be concise and
less ugly than other approaches. This adjusts the process naming
for devices to match, dropping the use of brackets.

In the process of this change, updating log settings dynamically
via vmctl(8) is fixed by properly broadcasting that information to
the device subprocesses. The "vmm" process also now updates its own
state properly, so settings survive vm reboots.

ok mlarkin@

/*	$OpenBSD: log.c,v 1.9 2023/09/26 01:53:54 dv Exp $	*/

/*
 * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <syslog.h>
#include <errno.h>
#include <time.h>

#include "proc.h"

static int	 debug;
static int	 verbose;
static char	 log_procname[2048];

void
log_init(int n_debug, int facility)
{
	extern char	*__progname;

	debug = n_debug;
	verbose = n_debug;
	log_procinit("%s", __progname);

	if (!debug)
		openlog(__progname, LOG_PID | LOG_NDELAY, facility);

	tzset();
}

void
log_procinit(const char *fmt, ...)
{
	va_list ap;
	va_start(ap, fmt);
	vsnprintf(log_procname, sizeof(log_procname), fmt, ap);
	va_end(ap);
}

void
log_setverbose(int v)
{
	verbose = v;
}

int
log_getverbose(void)
{
	return (verbose);
}

void
logit(int pri, const char *fmt, ...)
{
	va_list	ap;

	va_start(ap, fmt);
	vlog(pri, fmt, ap);
	va_end(ap);
}

void
vlog(int pri, const char *fmt, va_list ap)
{
	char	*nfmt;
	int	 saved_errno = errno;

	if (debug) {
		/* best effort in out of mem situations */
		if (asprintf(&nfmt, "%s: %s\n", log_procname, fmt) == -1) {
			vfprintf(stderr, fmt, ap);
			fprintf(stderr, "\n");
		} else {
			vfprintf(stderr, nfmt, ap);
			free(nfmt);
		}
		fflush(stderr);
	} else
		vsyslog(pri, fmt, ap);

	errno = saved_errno;
}

void
log_warn(const char *emsg, ...)
{
	char		*nfmt;
	va_list		 ap;
	int		 saved_errno = errno;

	/* best effort to even work in out of memory situations */
	if (emsg == NULL)
		logit(LOG_ERR, "%s", strerror(saved_errno));
	else {
		va_start(ap, emsg);

		if (asprintf(&nfmt, "%s: %s", emsg,
		    strerror(saved_errno)) == -1) {
			/* we tried it... */
			vlog(LOG_ERR, emsg, ap);
			logit(LOG_ERR, "%s", strerror(saved_errno));
		} else {
			vlog(LOG_ERR, nfmt, ap);
			free(nfmt);
		}
		va_end(ap);
	}

	errno = saved_errno;
}

void
log_warnx(const char *emsg, ...)
{
	va_list	 ap;

	va_start(ap, emsg);
	vlog(LOG_ERR, emsg, ap);
	va_end(ap);
}

void
log_info(const char *emsg, ...)
{
	va_list	 ap;

	va_start(ap, emsg);
	vlog(LOG_INFO, emsg, ap);
	va_end(ap);
}

void
log_debug(const char *emsg, ...)
{
	va_list	 ap;

	if (verbose > 1) {
		va_start(ap, emsg);
		vlog(LOG_DEBUG, emsg, ap);
		va_end(ap);
	}
}

static void
vfatalc(int code, const char *emsg, va_list ap)
{
	static char	s[BUFSIZ];
	const char	*sep;

	if (emsg != NULL) {
		(void)vsnprintf(s, sizeof(s), emsg, ap);
		sep = ": ";
	} else {
		s[0] = '\0';
		sep = "";
	}
	if (code)
		logit(LOG_CRIT, "%s: %s%s%s",
		    log_procname, s, sep, strerror(code));
	else
		logit(LOG_CRIT, "%s%s%s", log_procname, sep, s);
}

void
fatal(const char *emsg, ...)
{
	va_list	ap;

	va_start(ap, emsg);
	vfatalc(errno, emsg, ap);
	va_end(ap);
	exit(1);
}

void
fatalx(const char *emsg, ...)
{
	va_list	ap;

	va_start(ap, emsg);
	vfatalc(0, emsg, ap);
	va_end(ap);
	exit(1);
}