/*
  chronyd/chronyc - Programs for keeping computer clocks accurate.

 **********************************************************************
 * Copyright (C) Richard P. Curnow  1997-2003
 * Copyright (C) Miroslav Lichvar  2011-2014, 2018-2020
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 * 
 * This program 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
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 * 
 **********************************************************************

  =======================================================================

  Module to handle logging of diagnostic information
  */

#include "config.h"

#include "sysincl.h"

#include <syslog.h>

#include "conf.h"
#include "logging.h"
#include "memory.h"
#include "util.h"

/* This is used by DEBUG_LOG macro */
LOG_Severity log_min_severity = LOGS_INFO;

/* Current logging contexts */
static LOG_Context log_contexts;

/* ================================================== */
/* Flag indicating we have initialised */
static int initialised = 0;

static char *file_log_path = NULL;
static FILE *file_log = NULL;
static int system_log = 0;

static int parent_fd = 0;

struct LogFile {
  const char *name;
  const char *banner;
  FILE *file;
  unsigned long writes;
};

static int n_filelogs = 0;

/* Increase this when adding a new logfile */
#define MAX_FILELOGS 6

static struct LogFile logfiles[MAX_FILELOGS];

/* Global prefix for debug messages */
static char *debug_prefix;

/* ================================================== */
/* Init function */

void
LOG_Initialise(void)
{
  debug_prefix = Strdup("");
  log_contexts = 0;

  initialised = 1;
  LOG_OpenFileLog(NULL);
}

/* ================================================== */
/* Fini function */

void
LOG_Finalise(void)
{
  if (system_log)
    closelog();

  if (file_log && file_log != stderr)
    fclose(file_log);
  file_log = NULL;
  Free(file_log_path);
  file_log_path = NULL;

  LOG_CycleLogFiles();

  Free(debug_prefix);

  initialised = 0;
}

/* ================================================== */

static void log_message(int fatal, LOG_Severity severity, const char *message)
{
  if (system_log) {
    int priority;
    switch (severity) {
      case LOGS_DEBUG:
        priority = LOG_DEBUG;
        break;
      case LOGS_INFO:
        priority = LOG_INFO;
        break;
      case LOGS_WARN:
        priority = LOG_WARNING;
        break;
      case LOGS_ERR:
        priority = LOG_ERR;
        break;
      case LOGS_FATAL:
        priority = LOG_CRIT;
        break;
      default:
        assert(0);
    }
    syslog(priority, fatal ? "Fatal error : %s" : "%s", message);
  } else if (file_log) {
    fprintf(file_log, fatal ? "Fatal error : %s\n" : "%s\n", message);
  }
}

/* ================================================== */

void LOG_Message(LOG_Severity severity,
#if DEBUG > 0
                 int line_number, const char *filename, const char *function_name,
#endif
                 const char *format, ...)
{
  char buf[2048];
  va_list other_args;
  time_t t;
  struct tm *tm;

  assert(initialised);
  severity = CLAMP(LOGS_DEBUG, severity, LOGS_FATAL);

  if (!system_log && file_log && severity >= log_min_severity) {
    /* Don't clutter up syslog with timestamps and internal debugging info */
    time(&t);
    tm = gmtime(&t);
    if (tm) {
      strftime(buf, sizeof (buf), "%Y-%m-%dT%H:%M:%SZ", tm);
      fprintf(file_log, "%s ", buf);
    }
#if DEBUG > 0
    if (log_min_severity <= LOGS_DEBUG) {
      /* Log severity to character mapping (debug, info, warn, err, fatal) */
      const char severity_chars[LOGS_FATAL - LOGS_DEBUG + 1] = {'D', 'I', 'W', 'E', 'F'};

      fprintf(file_log, "%c:%s%s:%d:(%s) ", severity_chars[severity - LOGS_DEBUG],
              debug_prefix, filename, line_number, function_name);
    }
#endif
  }

  va_start(other_args, format);
  vsnprintf(buf, sizeof(buf), format, other_args);
  va_end(other_args);

  switch (severity) {
    case LOGS_DEBUG:
    case LOGS_INFO:
    case LOGS_WARN:
    case LOGS_ERR:
      if (severity >= log_min_severity)
        log_message(0, severity, buf);
      break;
    case LOGS_FATAL:
      if (severity >= log_min_severity)
        log_message(1, severity, buf);

      /* Send the message also to the foreground process if it is
         still running, or stderr if it is still open */
      if (parent_fd > 0) {
        if (!LOG_NotifyParent(buf))
          ; /* Not much we can do here */
      } else if (system_log && parent_fd == 0) {
        system_log = 0;
        log_message(1, severity, buf);
      }
      exit(1);
      break;
    default:
      assert(0);
  }
}

/* ================================================== */

static FILE *
open_file_log(const char *log_file, char mode)
{
  FILE *f;

  if (log_file) {
    f = UTI_OpenFile(NULL, log_file, NULL, mode, 0640);
  } else {
    f = stderr;
  }

  /* Enable line buffering */
  if (f)
    setvbuf(f, NULL, _IOLBF, BUFSIZ);

  return f;
}

/* ================================================== */

void
LOG_OpenFileLog(const char *log_file)
{
  if (file_log_path)
    Free(file_log_path);
  if (log_file)
    file_log_path = Strdup(log_file);
  else
    file_log_path = NULL;

  if (file_log && file_log != stderr)
    fclose(file_log);

  file_log = open_file_log(file_log_path, 'A');
}

/* ================================================== */

void
LOG_OpenSystemLog(void)
{
  system_log = 1;
  openlog("chronyd", LOG_PID, LOG_DAEMON);
}

/* ================================================== */

void LOG_SetMinSeverity(LOG_Severity severity)
{
  /* Don't print any debug messages in a non-debug build */
  log_min_severity = CLAMP(DEBUG > 0 ? LOGS_DEBUG : LOGS_INFO, severity, LOGS_FATAL);
}

/* ================================================== */

LOG_Severity
LOG_GetMinSeverity(void)
{
  return log_min_severity;
}

/* ================================================== */

void
LOG_SetContext(LOG_Context context)
{
  log_contexts |= context;
}

/* ================================================== */

void
LOG_UnsetContext(LOG_Context context)
{
  log_contexts &= ~context;
}

/* ================================================== */

LOG_Severity
LOG_GetContextSeverity(LOG_Context contexts)
{
  return log_contexts & contexts ? LOGS_INFO : LOGS_DEBUG;
}

/* ================================================== */

void
LOG_SetDebugPrefix(const char *prefix)
{
  Free(debug_prefix);
  debug_prefix = Strdup(prefix);
}

/* ================================================== */

void
LOG_SetParentFd(int fd)
{
  parent_fd = fd;
  if (file_log == stderr)
    file_log = NULL;
}

/* ================================================== */

int
LOG_NotifyParent(const char *message)
{
  if (parent_fd <= 0)
    return 1;

  return write(parent_fd, message, strlen(message) + 1) > 0;
}

/* ================================================== */

void
LOG_CloseParentFd()
{
  if (parent_fd > 0)
    close(parent_fd);
  parent_fd = -1;
}

/* ================================================== */

LOG_FileID
LOG_FileOpen(const char *name, const char *banner)
{
  if (n_filelogs >= MAX_FILELOGS) {
    assert(0);
    return -1;
  }

  logfiles[n_filelogs].name = name;
  logfiles[n_filelogs].banner = banner;
  logfiles[n_filelogs].file = NULL;
  logfiles[n_filelogs].writes = 0;

  return n_filelogs++;
}

/* ================================================== */

void
LOG_FileWrite(LOG_FileID id, const char *format, ...)
{
  va_list other_args;
  int banner;

  if (id < 0 || id >= n_filelogs || !logfiles[id].name)
    return;

  if (!logfiles[id].file) {
    char *logdir = CNF_GetLogDir();

    if (!logdir) {
      LOG(LOGS_WARN, "logdir not specified");
      logfiles[id].name = NULL;
      return;
    }

    logfiles[id].file = UTI_OpenFile(logdir, logfiles[id].name, ".log", 'a', 0644);
    if (!logfiles[id].file) {
      /* Disable the log */
      logfiles[id].name = NULL;
      return;
    }
  }

  banner = CNF_GetLogBanner();
  if (banner && logfiles[id].writes++ % banner == 0) {
    char bannerline[256];
    int i, bannerlen;

    bannerlen = MIN(strlen(logfiles[id].banner), sizeof (bannerline) - 1);

    for (i = 0; i < bannerlen; i++)
      bannerline[i] = '=';
    bannerline[i] = '\0';

    fprintf(logfiles[id].file, "%s\n", bannerline);
    fprintf(logfiles[id].file, "%s\n", logfiles[id].banner);
    fprintf(logfiles[id].file, "%s\n", bannerline);
  }

  va_start(other_args, format);
  vfprintf(logfiles[id].file, format, other_args);
  va_end(other_args);
  fprintf(logfiles[id].file, "\n");

  fflush(logfiles[id].file);
}

/* ================================================== */

void
LOG_CycleLogFiles(void)
{
  struct stat st;
  LOG_FileID i;
  FILE *f;

  /* The log will be opened later when an entry is logged */
  for (i = 0; i < n_filelogs; i++) {
    if (logfiles[i].file)
      fclose(logfiles[i].file);
    logfiles[i].file = NULL;
    logfiles[i].writes = 0;
  }

  /* Try to open the log specified by the -l option, but only if nothing is
     present at its path to avoid unnecessary error messages.  Keep the
     original file if that fails (the process might no longer have the
     necessary privileges to write in the directory). */
  if (file_log && file_log != stderr && stat(file_log_path, &st) < 0 && errno == ENOENT) {
    f = open_file_log(file_log_path, 'a');
    if (f) {
      fclose(file_log);
      file_log = f;
    }
  }
}

/* ================================================== */