/* syslog.cc

   Copyright 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
   2006 Red Hat, Inc.

This file is part of Cygwin.

This software is a copyrighted work licensed under the terms of the
Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
details. */

#define  __INSIDE_CYGWIN_NET__

#include "winsup.h"
#include <stdlib.h>
#include <stdio.h>
#include <syslog.h>
#include <stdarg.h>
#include <unistd.h>
#include <sys/un.h>
#include <sys/uio.h>
#include "cygerrno.h"
#include "security.h"
#include "path.h"
#include "fhandler.h"
#include "dtable.h"
#include "cygheap.h"
#include "thread.h"
#include "cygtls.h"

/* FIXME: These should probably be in the registry. */
/* FIXME: The Win95 path should be whatever slash is */

#define WIN95_EVENT_LOG_PATH "C:\\CYGWIN_SYSLOG.TXT"
#define CYGWIN_LOG_NAME "Cygwin"

/*
 * Utility function to help enable moving
 * WIN95_EVENT_LOG_PATH into registry later.
 */
static const char *
get_win95_event_log_path ()
{
  return WIN95_EVENT_LOG_PATH;
}

/* openlog: save the passed args. Don't open the
   system log (NT) or log file (95) yet.  */
extern "C" void
openlog (const char *ident, int logopt, int facility)
{
    debug_printf ("openlog called with (%s, %d, %d)",
		       ident ? ident : "<NULL>", logopt, facility);

    if (_my_tls.locals.process_ident != NULL)
      {
	free (_my_tls.locals.process_ident);
	_my_tls.locals.process_ident = NULL;
      }
    if (ident)
      {
	_my_tls.locals.process_ident = (char *) malloc (strlen (ident) + 1);
	if (!_my_tls.locals.process_ident)
	  {
	    debug_printf ("failed to allocate memory for _my_tls.locals.process_ident");
	    return;
	  }
	strcpy (_my_tls.locals.process_ident, ident);
      }
    _my_tls.locals.process_logopt = logopt;
    _my_tls.locals.process_facility = facility;
}

/* setlogmask: set the log priority mask and return previous mask.
   If maskpri is zero, just return previous. */
int
setlogmask (int maskpri)
{
  if (maskpri == 0)
    return _my_tls.locals.process_logmask;

  int old_mask = _my_tls.locals.process_logmask;
  _my_tls.locals.process_logmask = maskpri;

  return old_mask;
}

/* Private class used to handle formatting of syslog message
   It is named pass_handler because it does a two-pass handling of log
   strings.  The first pass counts the length of the string, and the second
   one builds the string. */

class pass_handler
{
  private:
    FILE *fp_;
    char *message_;
    int total_len_;

    void shutdown ();

    /* Explicitly disallow copies */
    pass_handler (const pass_handler &);
    pass_handler & operator = (const pass_handler &);

  public:
    pass_handler ();
    ~pass_handler ();

    int initialize (int);

    int print (const char *,...);
    int print_va (const char *, va_list);
    char *get_message () const { return message_; }
    void set_message (char *s) { message_ = s; *message_ = '\0'; }
};

pass_handler::pass_handler () : fp_ (0), message_ (0), total_len_ (0)
{
  ;
}

pass_handler::~pass_handler ()
{
  shutdown ();
}

void
pass_handler::shutdown ()
{
  if (fp_ != NULL)
    {
      fclose (fp_);
      fp_ = 0;
    }
}

int
pass_handler::initialize (int pass_number)
{
    shutdown ();
    if (pass_number)
      return total_len_ + 1;

    fp_ = fopen ("/dev/null", "wb");
    setbuf (fp_, NULL);
    if (fp_ == NULL)
      {
	debug_printf ("failed to open /dev/null");
	return -1;
      }
    total_len_ = 0;
    return 0;
}

int
pass_handler::print (const char *fmt, ...)
{
    va_list ap;
    va_start (ap, fmt);
    int ret = print_va (fmt, ap);
    va_end (ap);
    return ret;
}

int
pass_handler::print_va (const char *fmt, va_list list)
{
    if (fp_ != NULL)
      {
	int len = vfprintf (fp_, fmt, list);
	if (len < 0)
	  return -1;
	total_len_ += len;
	return 0;
      }
    else if (message_ != NULL)
      {
	char *printpos = &message_[strlen (message_)];
	vsprintf (printpos, fmt, list);
	return 0;
      }
    debug_printf ("FAILURE ! fp_ and message_ both 0!! ");
    return -1;
}

static NO_COPY muto try_connect_guard;
static enum {
  not_inited,
  inited_failed,
  inited_dgram,
  inited_stream
} syslogd_inited;
static int syslogd_sock = -1;
extern "C" int cygwin_socket (int, int, int);
extern "C" int cygwin_connect (int, const struct sockaddr *, int);

static void
connect_syslogd ()
{
  struct __stat64 st;
  int fd;
  struct sockaddr_un sun;

  if (syslogd_inited != not_inited && syslogd_sock >= 0)
    close (syslogd_sock);
  syslogd_inited = inited_failed;
  syslogd_sock = -1;
  if (stat64 (_PATH_LOG, &st) || !S_ISSOCK (st.st_mode))
    return;
  if ((fd = cygwin_socket (AF_LOCAL, SOCK_DGRAM, 0)) < 0)
    return;
  sun.sun_family = AF_LOCAL;
  strncpy (sun.sun_path, _PATH_LOG, sizeof sun.sun_path);
  if (cygwin_connect (fd, (struct sockaddr *) &sun, sizeof sun))
    {
      if (get_errno () != EPROTOTYPE)
	{
	  close (fd);
	  return;
	}
      /* Retry with SOCK_STREAM. */
      if ((fd = cygwin_socket (AF_LOCAL, SOCK_STREAM, 0)) < 0)
	return;
      if (cygwin_connect (fd, (struct sockaddr *) &sun, sizeof sun))
	{
	  close (fd);
	  return;
	}
      syslogd_inited = inited_stream;
    }
  else
    syslogd_inited = inited_dgram;
  syslogd_sock = fd;
  fcntl (syslogd_sock, F_SETFD, FD_CLOEXEC);
  return;
}

static int
try_connect_syslogd (int priority, const char *msg, int len)
{
  ssize_t ret = -1;

  try_connect_guard.init ("try_connect_guard")->acquire ();
  if (syslogd_inited == not_inited)
    connect_syslogd ();
  if (syslogd_sock >= 0)
    {
      char pribuf[16];
      sprintf (pribuf, "<%d>", priority);
      struct iovec iv[2] =
      {
	{ pribuf, strlen (pribuf) },
	{ (char *) msg, len }
      };

      ret = writev (syslogd_sock, iv, 2);
      /* If the syslog daemon has been restarted and /dev/log was
	 a stream socket, the connection is broken.  In this case,
	 try to reopen the socket and try again. */
      if (ret < 0 && syslogd_inited == inited_stream)
	{
	  connect_syslogd ();
	  if (syslogd_sock >= 0)
	    ret = writev (syslogd_sock, iv, 2);
	}
      /* If write fails and LOG_CONS is set, return failure to vsyslog so
	 it falls back to the usual logging method for this OS. */
      if (ret >= 0 || !(_my_tls.locals.process_logopt & LOG_CONS))
	ret = syslogd_sock;
    }
  try_connect_guard.release ();
  return ret;
}

/*
 * syslog: creates the log message and writes to system
 * log (NT) or log file (95). FIXME. WinNT log error messages
 * don't look pretty, but in order to fix this we have to
 * embed resources in the code and tell the NT registry
 * where we are, blech (what happens if we move ?).
 * We could, however, add the resources in Cygwin and
 * always point to that.
 */

extern "C" void
vsyslog (int priority, const char *message, va_list ap)
{
    debug_printf ("%x %s", priority, message);
    /* If the priority fails the current mask, reject */
    if ((LOG_MASK (LOG_PRI (priority)) & _my_tls.locals.process_logmask) == 0)
      {
	debug_printf ("failing message %x due to priority mask %x",
		      priority, _my_tls.locals.process_logmask);
	return;
      }

    /* Add default facility if not in the given priority. */
    if (!(priority & LOG_FACMASK))
      priority |= _my_tls.locals.process_facility;

    /* Translate %m in the message to error text */
    char *errtext = strerror (get_errno ());
    int errlen = strlen (errtext);
    int numfound = 0;

    for (const char *cp = message; *cp; cp++)
      if (*cp == '%' && cp[1] == 'm')
	numfound++;

    char *newmessage = (char *) alloca (strlen (message) +
					(errlen * numfound) + 1);

    if (newmessage == NULL)
      {
	debug_printf ("failed to allocate newmessage");
	return;
      }

    char *dst = newmessage;
    for (const char *cp2 = message; *cp2; cp2++)
      if (*cp2 == '%' && cp2[1] == 'm')
	{
	  cp2++;
	  strcpy (dst, errtext);
	  while (*dst)
	    dst++;
	}
      else
	*dst++ = *cp2;

    *dst = '\0';
    message = newmessage;

    /* Work out the priority type - we ignore the facility for now.. */
    WORD eventType;
    switch (LOG_PRI (priority))
      {
      case LOG_EMERG:
      case LOG_ALERT:
      case LOG_CRIT:
      case LOG_ERR:
	eventType = EVENTLOG_ERROR_TYPE;
	break;
      case LOG_WARNING:
	eventType = EVENTLOG_WARNING_TYPE;
	break;
      case LOG_NOTICE:
      case LOG_INFO:
      case LOG_DEBUG:
	eventType = EVENTLOG_INFORMATION_TYPE;
	break;
      default:
	eventType = EVENTLOG_ERROR_TYPE;
	break;
      }

    /* We need to know how long the buffer needs to be.
       The only legal way I can see of doing this is to
       do a vfprintf to /dev/null, and count the bytes
       output, then do it again to a malloc'ed string. This
       is ugly, slow, but prevents core dumps :-).
     */
    pass_handler pass;
    for (int pass_number = 0; pass_number < 2; ++pass_number)
      {
	int n = pass.initialize (pass_number);
	if (n == -1)
	  return;
	else if (n > 0)
	  pass.set_message ((char *) alloca (n));

	/* Deal with ident_string */
	if (_my_tls.locals.process_ident != NULL)
	  {
	    if (pass.print ("%s: ", _my_tls.locals.process_ident) == -1)
	      return;
	  }
	if (_my_tls.locals.process_logopt & LOG_PID)
	  {
	    if (pass.print ("PID %u: ", getpid ()) == -1)
	      return;
	  }

	if (!wincap.has_eventlog ())
	  {
	    /* Add a priority string - not needed for systems with
	       eventlog capability. */
	    switch (LOG_PRI (priority))
	      {
	     case LOG_EMERG:
	       pass.print ("%s: ", "LOG_EMERG");
	       break;
	     case LOG_ALERT:
	       pass.print ("%s: ", "LOG_ALERT");
	       break;
	     case LOG_CRIT:
	       pass.print ("%s: ", "LOG_CRIT");
	       break;
	      case LOG_ERR:
		pass.print ("%s: ", "LOG_ERR");
		break;
	      case LOG_WARNING:
		pass.print ("%s: ", "LOG_WARNING");
		break;
	     case LOG_NOTICE:
	       pass.print ("%s: ", "LOG_NOTICE");
	       break;
	      case LOG_INFO:
		pass.print ("%s: ", "LOG_INFO");
	       break;
	     case LOG_DEBUG:
	       pass.print ("%s: ", "LOG_DEBUG");
		break;
	      default:
		pass.print ("%s: ", "LOG_ERR");
		break;
	      }
	  }

	/* Print out the variable part */
	if (pass.print_va (message, ap) == -1)
	  return;

      }
    const char *msg_strings[1];
    char *total_msg = pass.get_message ();
    int len = strlen (total_msg);
    if (len != 0 && (total_msg[len - 1] == '\n'))
      total_msg[--len] = '\0';

    msg_strings[0] = total_msg;

    if (_my_tls.locals.process_logopt & LOG_PERROR)
      {
	write (STDERR_FILENO, total_msg, len);
	write (STDERR_FILENO, "\n", 1);
      }

    int fd;
    if ((fd = try_connect_syslogd (priority, total_msg, len + 1)) >= 0)
      ;
    else if (wincap.has_eventlog ())
      {
	/* For NT, open the event log and send the message */
	HANDLE hEventSrc = RegisterEventSourceA (NULL, (_my_tls.locals.process_ident != NULL) ?
					 _my_tls.locals.process_ident : CYGWIN_LOG_NAME);
	if (hEventSrc == NULL)
	  {
	    debug_printf ("RegisterEventSourceA failed with %E");
	    return;
	  }
	if (!ReportEventA (hEventSrc, eventType, 0, 0,
			   cygheap->user.sid (), 1, 0, msg_strings, NULL))
	  debug_printf ("ReportEventA failed with %E");
	DeregisterEventSource (hEventSrc);
      }
    else
      {
	/* Under Windows 95, append the message to the log file */
	char timestamp[24];
	time_t ctime;
	FILE *fp = fopen (get_win95_event_log_path (), "a");
	if (fp == NULL)
	  {
	    debug_printf ("failed to open file %s",
			  get_win95_event_log_path ());
	    return;
	  }
	strftime (timestamp, sizeof timestamp, "%Y-%m-%d %H:%M:%S : ",
		  localtime (&(ctime = time (NULL))));

	/* Now to prevent several syslog messages from being
	   interleaved, we must lock the first byte of the file
	   This works on Win32 even if we created the file above.
	*/
	HANDLE fHandle = cygheap->fdtab[fileno (fp)]->get_handle ();
	for (int i = 0;; i++)
	  if (LockFile (fHandle, 0, 0, 1, 0) == FALSE)
	    if (i == 3)
	      {
		debug_printf ("failed to lock file %s", get_win95_event_log_path ());
		fclose (fp);
		return;
	      }
	    else
	      usleep (1000);
	  else
	    break;
	fputs (timestamp, fp);
	fputs (msg_strings[0], fp);
	fputc ('\n', fp);
	fclose (fp);
      }
}

extern "C" void
syslog (int priority, const char *message, ...)
{
  va_list ap;
  va_start (ap, message);
  vsyslog (priority, message, ap);
  va_end (ap);
}

static NO_COPY muto klog_guard;
fhandler_mailslot *dev_kmsg;

extern "C" void
vklog (int priority, const char *message, va_list ap)
{
  /* TODO: kernel messages are under our control entirely and they should
     be quick.  No playing with /dev/null, but a fixed upper size for now. */
  char buf[2060];	/* 2048 + a prority */
  if (!(priority & ~LOG_PRIMASK))
    priority = LOG_KERN | LOG_PRI (priority);
  __small_sprintf (buf, "<%d>", priority);
  __small_vsprintf (buf + strlen (buf), message, ap);
  klog_guard.init ("klog_guard")->acquire ();
  if (!dev_kmsg)
    dev_kmsg = (fhandler_mailslot *) build_fh_name ("/dev/kmsg");
  if (dev_kmsg && !dev_kmsg->get_handle ())
    dev_kmsg->open (O_WRONLY, 0);
  if (dev_kmsg && dev_kmsg->get_handle ())
    dev_kmsg->write (buf, strlen (buf) + 1);
  klog_guard.release ();
}

extern "C" void
klog (int priority, const char *message, ...)
{
  va_list ap;
  va_start (ap, message);
  vklog (priority, message, ap);
  va_end (ap);
}

extern "C" void
closelog (void)
{
  try_connect_guard.init ("try_connect_guard")->acquire ();
  if (syslogd_inited != not_inited && syslogd_sock >= 0)
    {
      close (syslogd_sock);
      syslogd_sock = -1;
      syslogd_inited = not_inited;
    }
  try_connect_guard.release ();
}