Adding upstream version 4.94.2.upstream/4.94.2upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1525 insertions, 0 deletions

diff --git a/src/log.c b/src/log.c
new file mode 100644
index 0000000..5d36b49
--- /dev/null
+++ b/src/log.c
@@ -0,0 +1,1525 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2018 */
+/* Copyright (c) The Exim Maintainers 2020 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* Functions for writing log files. The code for maintaining datestamped
+log files was originally contributed by Tony Sheen. */
+
+
+#include "exim.h"
+
+#define LOG_NAME_SIZE 256
+#define MAX_SYSLOG_LEN 870
+
+#define LOG_MODE_FILE   1
+#define LOG_MODE_SYSLOG 2
+
+enum { lt_main, lt_reject, lt_panic, lt_debug };
+
+static uschar *log_names[] = { US"main", US"reject", US"panic", US"debug" };
+
+
+
+/*************************************************
+*           Local static variables               *
+*************************************************/
+
+static uschar mainlog_name[LOG_NAME_SIZE];
+static uschar rejectlog_name[LOG_NAME_SIZE];
+static uschar debuglog_name[LOG_NAME_SIZE];
+
+static uschar *mainlog_datestamp = NULL;
+static uschar *rejectlog_datestamp = NULL;
+
+static int    mainlogfd = -1;
+static int    rejectlogfd = -1;
+static ino_t  mainlog_inode = 0;
+static ino_t  rejectlog_inode = 0;
+
+static uschar *panic_save_buffer = NULL;
+static BOOL   panic_recurseflag = FALSE;
+
+static BOOL   syslog_open = FALSE;
+static BOOL   path_inspected = FALSE;
+static int    logging_mode = LOG_MODE_FILE;
+static uschar *file_path = US"";
+
+static size_t pid_position[2];
+
+
+/* These should be kept in-step with the private delivery error
+number definitions in macros.h */
+
+static const uschar * exim_errstrings[] = {
+  US"",
+  US"unknown error",
+  US"user slash",
+  US"exist race",
+  US"not regular",
+  US"not directory",
+  US"bad ugid",
+  US"bad mode",
+  US"inode changed",
+  US"lock failed",
+  US"bad address2",
+  US"forbid pipe",
+  US"forbid file",
+  US"forbid reply",
+  US"missing pipe",
+  US"missing file",
+  US"missing reply",
+  US"bad redirect",
+  US"smtp closed",
+  US"smtp format",
+  US"spool format",
+  US"not absolute",
+  US"Exim-imposed quota",
+  US"held",
+  US"Delivery filter process failure",
+  US"Delivery add/remove header failure",
+  US"Delivery write incomplete error",
+  US"Some expansion failed",
+  US"Failed to get gid",
+  US"Failed to get uid",
+  US"Unset or non-existent transport",
+  US"MBX length mismatch",
+  US"Lookup failed routing or in smtp tpt",
+  US"Can't match format in appendfile",
+  US"Creation outside home in appendfile",
+  US"Can't check a list; lookup defer",
+  US"DNS lookup defer",
+  US"Failed to start TLS session",
+  US"Mandatory TLS session not started",
+  US"Failed to chown a file",
+  US"Failed to create a pipe",
+  US"When verifying",
+  US"When required by client",
+  US"Used internally in smtp transport",
+  US"RCPT gave 4xx error",
+  US"MAIL gave 4xx error",
+  US"DATA gave 4xx error",
+  US"Negotiation failed for proxy configured host",
+  US"Authenticator 'other' failure",
+  US"target not supporting SMTPUTF8",
+  US"",
+
+  US"Not time for routing",
+  US"Not time for local delivery",
+  US"Not time for any remote host",
+  US"Local-only delivery",
+  US"Domain in queue_domains",
+  US"Transport concurrency limit",
+  US"Event requests alternate response",
+};
+
+
+/************************************************/
+const uschar *
+exim_errstr(int err)
+{
+return err < 0 ? exim_errstrings[-err] : CUS strerror(err);
+}
+
+/*************************************************
+*              Write to syslog                   *
+*************************************************/
+
+/* The given string is split into sections according to length, or at embedded
+newlines, and syslogged as a numbered sequence if it is overlong or if there is
+more than one line. However, if we are running in the test harness, do not do
+anything. (The test harness doesn't use syslog - for obvious reasons - but we
+can get here if there is a failure to open the panic log.)
+
+Arguments:
+  priority       syslog priority
+  s              the string to be written
+
+Returns:         nothing
+*/
+
+static void
+write_syslog(int priority, const uschar *s)
+{
+int len;
+int linecount = 0;
+
+if (!syslog_pid && LOGGING(pid))
+  s = string_sprintf("%.*s%s", (int)pid_position[0], s, s + pid_position[1]);
+if (!syslog_timestamp)
+  {
+  len = log_timezone ? 26 : 20;
+  if (LOGGING(millisec)) len += 4;
+  s += len;
+  }
+
+len = Ustrlen(s);
+
+#ifndef NO_OPENLOG
+if (!syslog_open && !f.running_in_test_harness)
+  {
+# ifdef SYSLOG_LOG_PID
+  openlog(CS syslog_processname, LOG_PID|LOG_CONS, syslog_facility);
+# else
+  openlog(CS syslog_processname, LOG_CONS, syslog_facility);
+# endif
+  syslog_open = TRUE;
+  }
+#endif
+
+/* First do a scan through the message in order to determine how many lines
+it is going to end up as. Then rescan to output it. */
+
+for (int pass = 0; pass < 2; pass++)
+  {
+  const uschar * ss = s;
+  for (int i = 1, tlen = len; tlen > 0; i++)
+    {
+    int plen = tlen;
+    uschar *nlptr = Ustrchr(ss, '\n');
+    if (nlptr != NULL) plen = nlptr - ss;
+#ifndef SYSLOG_LONG_LINES
+    if (plen > MAX_SYSLOG_LEN) plen = MAX_SYSLOG_LEN;
+#endif
+    tlen -= plen;
+    if (ss[plen] == '\n') tlen--;    /* chars left */
+
+    if (pass == 0)
+      linecount++;
+    else if (f.running_in_test_harness)
+      if (linecount == 1)
+        fprintf(stderr, "SYSLOG: '%.*s'\n", plen, ss);
+      else
+        fprintf(stderr, "SYSLOG: '[%d%c%d] %.*s'\n", i,
+          ss[plen] == '\n' && tlen != 0 ? '\\' : '/',
+          linecount, plen, ss);
+    else
+      if (linecount == 1)
+        syslog(priority, "%.*s", plen, ss);
+      else
+        syslog(priority, "[%d%c%d] %.*s", i,
+          ss[plen] == '\n' && tlen != 0 ? '\\' : '/',
+          linecount, plen, ss);
+
+    ss += plen;
+    if (*ss == '\n') ss++;
+    }
+  }
+}
+
+
+
+/*************************************************
+*             Die tidily                         *
+*************************************************/
+
+/* This is called when Exim is dying as a result of something going wrong in
+the logging, or after a log call with LOG_PANIC_DIE set. Optionally write a
+message to debug_file or a stderr file, if they exist. Then, if in the middle
+of accepting a message, throw it away tidily by calling receive_bomb_out();
+this will attempt to send an SMTP response if appropriate. Passing NULL as the
+first argument stops it trying to run the NOTQUIT ACL (which might try further
+logging and thus cause problems). Otherwise, try to close down an outstanding
+SMTP call tidily.
+
+Arguments:
+  s1         Error message to write to debug_file and/or stderr and syslog
+  s2         Error message for any SMTP call that is in progress
+Returns:     The function does not return
+*/
+
+static void
+die(uschar *s1, uschar *s2)
+{
+if (s1)
+  {
+  write_syslog(LOG_CRIT, s1);
+  if (debug_file) debug_printf("%s\n", s1);
+  if (log_stderr && log_stderr != debug_file)
+    fprintf(log_stderr, "%s\n", s1);
+  }
+if (f.receive_call_bombout) receive_bomb_out(NULL, s2);  /* does not return */
+if (smtp_input) smtp_closedown(s2);
+exim_exit(EXIT_FAILURE);
+}
+
+
+
+/*************************************************
+*             Create a log file                  *
+*************************************************/
+
+/* This function is called to create and open a log file. It may be called in a
+subprocess when the original process is root.
+
+Arguments:
+  name         the file name
+
+The file name has been build in a working buffer, so it is permissible to
+overwrite it temporarily if it is necessary to create the directory.
+
+Returns:       a file descriptor, or < 0 on failure (errno set)
+*/
+
+static int
+log_open_already_exim(uschar * const name)
+{
+int fd = -1;
+const int flags = O_WRONLY | O_APPEND | O_CREAT | O_NONBLOCK;
+
+if (geteuid() != exim_uid)
+  {
+  errno = EACCES;
+  return -1;
+  }
+
+fd = Uopen(name, flags, LOG_MODE);
+
+/* If creation failed, attempt to build a log directory in case that is the
+problem. */
+
+if (fd < 0 && errno == ENOENT)
+  {
+  BOOL created;
+  uschar *lastslash = Ustrrchr(name, '/');
+  *lastslash = 0;
+  created = directory_make(NULL, name, LOG_DIRECTORY_MODE, FALSE);
+  DEBUG(D_any) debug_printf("%s log directory %s\n",
+    created ? "created" : "failed to create", name);
+  *lastslash = '/';
+  if (created) fd = Uopen(name, flags, LOG_MODE);
+  }
+
+return fd;
+}
+
+
+
+/* Inspired by OpenSSH's mm_send_fd(). Thanks! */
+
+static int
+log_send_fd(const int sock, const int fd)
+{
+struct msghdr msg;
+union {
+  struct cmsghdr hdr;
+  char buf[CMSG_SPACE(sizeof(int))];
+} cmsgbuf;
+struct cmsghdr *cmsg;
+struct iovec vec;
+char ch = 'A';
+ssize_t n;
+
+memset(&msg, 0, sizeof(msg));
+memset(&cmsgbuf, 0, sizeof(cmsgbuf));
+msg.msg_control = &cmsgbuf.buf;
+msg.msg_controllen = sizeof(cmsgbuf.buf);
+
+cmsg = CMSG_FIRSTHDR(&msg);
+cmsg->cmsg_len = CMSG_LEN(sizeof(int));
+cmsg->cmsg_level = SOL_SOCKET;
+cmsg->cmsg_type = SCM_RIGHTS;
+*(int *)CMSG_DATA(cmsg) = fd;
+
+vec.iov_base = &ch;
+vec.iov_len = 1;
+msg.msg_iov = &vec;
+msg.msg_iovlen = 1;
+
+while ((n = sendmsg(sock, &msg, 0)) == -1 && errno == EINTR);
+if (n != 1) return -1;
+return 0;
+}
+
+/* Inspired by OpenSSH's mm_receive_fd(). Thanks! */
+
+static int
+log_recv_fd(const int sock)
+{
+struct msghdr msg;
+union {
+  struct cmsghdr hdr;
+  char buf[CMSG_SPACE(sizeof(int))];
+} cmsgbuf;
+struct cmsghdr *cmsg;
+struct iovec vec;
+ssize_t n;
+char ch = '\0';
+int fd = -1;
+
+memset(&msg, 0, sizeof(msg));
+vec.iov_base = &ch;
+vec.iov_len = 1;
+msg.msg_iov = &vec;
+msg.msg_iovlen = 1;
+
+memset(&cmsgbuf, 0, sizeof(cmsgbuf));
+msg.msg_control = &cmsgbuf.buf;
+msg.msg_controllen = sizeof(cmsgbuf.buf);
+
+while ((n = recvmsg(sock, &msg, 0)) == -1 && errno == EINTR);
+if (n != 1 || ch != 'A') return -1;
+
+cmsg = CMSG_FIRSTHDR(&msg);
+if (cmsg == NULL) return -1;
+if (cmsg->cmsg_type != SCM_RIGHTS) return -1;
+fd = *(const int *)CMSG_DATA(cmsg);
+if (fd < 0) return -1;
+return fd;
+}
+
+
+
+/*************************************************
+*     Create a log file as the exim user         *
+*************************************************/
+
+/* This function is called when we are root to spawn an exim:exim subprocess
+in which we can create a log file. It must be signal-safe since it is called
+by the usr1_handler().
+
+Arguments:
+  name         the file name
+
+Returns:       a file descriptor, or < 0 on failure (errno set)
+*/
+
+int
+log_open_as_exim(uschar * const name)
+{
+int fd = -1;
+const uid_t euid = geteuid();
+
+if (euid == exim_uid)
+  {
+  fd = log_open_already_exim(name);
+  }
+else if (euid == root_uid)
+  {
+  int sock[2];
+  if (socketpair(AF_UNIX, SOCK_STREAM, 0, sock) == 0)
+    {
+    const pid_t pid = exim_fork(US"logfile-open");
+    if (pid == 0)
+      {
+      (void)close(sock[0]);
+      if (setgroups(1, &exim_gid) != 0) _exit(EXIT_FAILURE);
+      if (setgid(exim_gid) != 0) _exit(EXIT_FAILURE);
+      if (setuid(exim_uid) != 0) _exit(EXIT_FAILURE);
+
+      if (getuid() != exim_uid || geteuid() != exim_uid) _exit(EXIT_FAILURE);
+      if (getgid() != exim_gid || getegid() != exim_gid) _exit(EXIT_FAILURE);
+
+      fd = log_open_already_exim(name);
+      if (fd < 0) _exit(EXIT_FAILURE);
+      if (log_send_fd(sock[1], fd) != 0) _exit(EXIT_FAILURE);
+      (void)close(sock[1]);
+      _exit(EXIT_SUCCESS);
+      }
+
+    (void)close(sock[1]);
+    if (pid > 0)
+      {
+      fd = log_recv_fd(sock[0]);
+      while (waitpid(pid, NULL, 0) == -1 && errno == EINTR);
+      }
+    (void)close(sock[0]);
+    }
+  }
+
+if (fd >= 0)
+  {
+  int flags;
+  flags = fcntl(fd, F_GETFD);
+  if (flags != -1) (void)fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
+  flags = fcntl(fd, F_GETFL);
+  if (flags != -1) (void)fcntl(fd, F_SETFL, flags & ~O_NONBLOCK);
+  }
+else
+  {
+  errno = EACCES;
+  }
+
+return fd;
+}
+
+
+
+
+/*************************************************
+*                Open a log file                 *
+*************************************************/
+
+/* This function opens one of a number of logs, creating the log directory if
+it does not exist. This may be called recursively on failure, in order to open
+the panic log.
+
+The directory is in the static variable file_path. This is static so that it
+the work of sorting out the path is done just once per Exim process.
+
+Exim is normally configured to avoid running as root wherever possible, the log
+files must be owned by the non-privileged exim user. To ensure this, first try
+an open without O_CREAT - most of the time this will succeed. If it fails, try
+to create the file; if running as root, this must be done in a subprocess to
+avoid races.
+
+Arguments:
+  fd         where to return the resulting file descriptor
+  type       lt_main, lt_reject, lt_panic, or lt_debug
+  tag        optional tag to include in the name (only hooked up for debug)
+
+Returns:   nothing
+*/
+
+static void
+open_log(int *fd, int type, uschar *tag)
+{
+uid_t euid;
+BOOL ok, ok2;
+uschar buffer[LOG_NAME_SIZE];
+
+/* The names of the log files are controlled by file_path. The panic log is
+written to the same directory as the main and reject logs, but its name does
+not have a datestamp. The use of datestamps is indicated by %D/%M in file_path.
+When opening the panic log, if %D or %M is present, we remove the datestamp
+from the generated name; if it is at the start, remove a following
+non-alphanumeric character as well; otherwise, remove a preceding
+non-alphanumeric character. This is definitely kludgy, but it sort of does what
+people want, I hope. */
+
+ok = string_format(buffer, sizeof(buffer), CS file_path, log_names[type]);
+
+/* Save the name of the mainlog for rollover processing. Without a datestamp,
+it gets statted to see if it has been cycled. With a datestamp, the datestamp
+will be compared. The static slot for saving it is the same size as buffer,
+and the text has been checked above to fit, so this use of strcpy() is OK. */
+
+if (type == lt_main && string_datestamp_offset >= 0)
+  {
+  Ustrcpy(mainlog_name, buffer);
+  mainlog_datestamp = mainlog_name + string_datestamp_offset;
+  }
+
+/* Ditto for the reject log */
+
+else if (type == lt_reject && string_datestamp_offset >= 0)
+  {
+  Ustrcpy(rejectlog_name, buffer);
+  rejectlog_datestamp = rejectlog_name + string_datestamp_offset;
+  }
+
+/* and deal with the debug log (which keeps the datestamp, but does not
+update it) */
+
+else if (type == lt_debug)
+  {
+  Ustrcpy(debuglog_name, buffer);
+  if (tag)
+    {
+    /* this won't change the offset of the datestamp */
+    ok2 = string_format(buffer, sizeof(buffer), "%s%s",
+      debuglog_name, tag);
+    if (ok2)
+      Ustrcpy(debuglog_name, buffer);
+    }
+  }
+
+/* Remove any datestamp if this is the panic log. This is rare, so there's no
+need to optimize getting the datestamp length. We remove one non-alphanumeric
+char afterwards if at the start, otherwise one before. */
+
+else if (string_datestamp_offset >= 0)
+  {
+  uschar * from = buffer + string_datestamp_offset;
+  uschar * to = from + string_datestamp_length;
+
+  if (from == buffer || from[-1] == '/')
+    {
+    if (!isalnum(*to)) to++;
+    }
+  else
+    if (!isalnum(from[-1])) from--;
+
+  /* This copy is ok, because we know that to is a substring of from. But
+  due to overlap we must use memmove() not Ustrcpy(). */
+  memmove(from, to, Ustrlen(to)+1);
+  }
+
+/* If the file name is too long, it is an unrecoverable disaster */
+
+if (!ok)
+  die(US"exim: log file path too long: aborting",
+      US"Logging failure; please try later");
+
+/* We now have the file name. After a successful open, return. */
+
+*fd = log_open_as_exim(buffer);
+
+if (*fd >= 0)
+  {
+  return;
+  }
+
+euid = geteuid();
+
+/* Creation failed. There are some circumstances in which we get here when
+the effective uid is not root or exim, which is the problem. (For example, a
+non-setuid binary with log_arguments set, called in certain ways.) Rather than
+just bombing out, force the log to stderr and carry on if stderr is available.
+*/
+
+if (euid != root_uid && euid != exim_uid && log_stderr)
+  {
+  *fd = fileno(log_stderr);
+  return;
+  }
+
+/* Otherwise this is a disaster. This call is deliberately ONLY to the panic
+log. If possible, save a copy of the original line that was being logged. If we
+are recursing (can't open the panic log either), the pointer will already be
+set.  Also, when we had to use a subprocess for the create we didn't retrieve
+errno from it, so get the error from the open attempt above (which is often
+meaningful enough, so leave it). */
+
+if (!panic_save_buffer)
+  if ((panic_save_buffer = US malloc(LOG_BUFFER_SIZE)))
+    memcpy(panic_save_buffer, log_buffer, LOG_BUFFER_SIZE);
+
+log_write(0, LOG_PANIC_DIE, "Cannot open %s log file \"%s\": %s: "
+  "euid=%d egid=%d", log_names[type], buffer, strerror(errno), euid, getegid());
+/* Never returns */
+}
+
+
+static void
+unlink_log(int type)
+{
+if (type == lt_debug) unlink(CS debuglog_name);
+}
+
+
+
+/*************************************************
+*     Add configuration file info to log line    *
+*************************************************/
+
+/* This is put in a function because it's needed twice (once for debugging,
+once for real).
+
+Arguments:
+  ptr         pointer to the end of the line we are building
+  flags       log flags
+
+Returns:      updated pointer
+*/
+
+static gstring *
+log_config_info(gstring * g, int flags)
+{
+g = string_cat(g, US"Exim configuration error");
+
+if (flags & (LOG_CONFIG_FOR & ~LOG_CONFIG))
+  return string_cat(g, US" for ");
+
+if (flags & (LOG_CONFIG_IN & ~LOG_CONFIG))
+  g = string_fmt_append(g, " in line %d of %s", config_lineno, config_filename);
+
+return string_catn(g, US":\n  ", 4);
+}
+
+
+/*************************************************
+*           A write() operation failed           *
+*************************************************/
+
+/* This function is called when write() fails on anything other than the panic
+log, which can happen if a disk gets full or a file gets too large or whatever.
+We try to save the relevant message in the panic_save buffer before crashing
+out.
+
+The potential invoker should probably not call us for EINTR -1 writes.  But
+otherwise, short writes are bad as we don't do non-blocking writes to fds
+subject to flow control.  (If we do, that's new and the logic of this should
+be reconsidered).
+
+Arguments:
+  name      the name of the log being written
+  length    the string length being written
+  rc        the return value from write()
+
+Returns:    does not return
+*/
+
+static void
+log_write_failed(uschar *name, int length, int rc)
+{
+int save_errno = errno;
+
+if (!panic_save_buffer)
+  if ((panic_save_buffer = US malloc(LOG_BUFFER_SIZE)))
+    memcpy(panic_save_buffer, log_buffer, LOG_BUFFER_SIZE);
+
+log_write(0, LOG_PANIC_DIE, "failed to write to %s: length=%d result=%d "
+  "errno=%d (%s)", name, length, rc, save_errno,
+  (save_errno == 0)? "write incomplete" : strerror(save_errno));
+/* Never returns */
+}
+
+
+
+/*************************************************
+*     Write to an fd, retrying after signals     *
+*************************************************/
+
+/* Basic write to fd for logs, handling EINTR.
+
+Arguments:
+  fd        the fd to write to
+  buf       the string to write
+  length    the string length being written
+
+Returns:
+  length actually written, persisting an errno from write()
+*/
+ssize_t
+write_to_fd_buf(int fd, const uschar *buf, size_t length)
+{
+ssize_t wrote;
+size_t total_written = 0;
+const uschar *p = buf;
+size_t left = length;
+
+while (1)
+  {
+  wrote = write(fd, p, left);
+  if (wrote == (ssize_t)-1)
+    {
+    if (errno == EINTR) continue;
+    return wrote;
+    }
+  total_written += wrote;
+  if (wrote == left)
+    break;
+  else
+    {
+    p += wrote;
+    left -= wrote;
+    }
+  }
+return total_written;
+}
+
+
+
+static void
+set_file_path(void)
+{
+int sep = ':';              /* Fixed separator - outside use */
+uschar *t;
+const uschar *tt = US LOG_FILE_PATH;
+while ((t = string_nextinlist(&tt, &sep, log_buffer, LOG_BUFFER_SIZE)))
+  {
+  if (Ustrcmp(t, "syslog") == 0 || t[0] == 0) continue;
+  file_path = string_copy(t);
+  break;
+  }
+}
+
+
+void
+mainlog_close(void)
+{
+if (mainlogfd < 0) return;
+(void)close(mainlogfd);
+mainlogfd = -1;
+mainlog_inode = 0;
+}
+
+/*************************************************
+*            Write message to log file           *
+*************************************************/
+
+/* Exim can be configured to log to local files, or use syslog, or both. This
+is controlled by the setting of log_file_path. The following cases are
+recognized:
+
+  log_file_path = ""               write files in the spool/log directory
+  log_file_path = "xxx"            write files in the xxx directory
+  log_file_path = "syslog"         write to syslog
+  log_file_path = "syslog : xxx"   write to syslog and to files (any order)
+
+The message always gets '\n' added on the end of it, since more than one
+process may be writing to the log at once and we don't want intermingling to
+happen in the middle of lines. To be absolutely sure of this we write the data
+into a private buffer and then put it out in a single write() call.
+
+The flags determine which log(s) the message is written to, or for syslogging,
+which priority to use, and in the case of the panic log, whether the process
+should die afterwards.
+
+The variable really_exim is TRUE only when exim is running in privileged state
+(i.e. not with a changed configuration or with testing options such as -brw).
+If it is not, don't try to write to the log because permission will probably be
+denied.
+
+Avoid actually writing to the logs when exim is called with -bv or -bt to
+test an address, but take other actions, such as panicking.
+
+In Exim proper, the buffer for building the message is got at start-up, so that
+nothing gets done if it can't be got. However, some functions that are also
+used in utilities occasionally obey log_write calls in error situations, and it
+is simplest to put a single malloc() here rather than put one in each utility.
+Malloc is used directly because the store functions may call log_write().
+
+If a message_id exists, we include it after the timestamp.
+
+Arguments:
+  selector  write to main log or LOG_INFO only if this value is zero, or if
+              its bit is set in log_selector[0]
+  flags     each bit indicates some independent action:
+              LOG_SENDER      add raw sender to the message
+              LOG_RECIPIENTS  add raw recipients list to message
+              LOG_CONFIG      add "Exim configuration error"
+              LOG_CONFIG_FOR  add " for " instead of ":\n  "
+              LOG_CONFIG_IN   add " in line x[ of file y]"
+              LOG_MAIN        write to main log or syslog LOG_INFO
+              LOG_REJECT      write to reject log or syslog LOG_NOTICE
+              LOG_PANIC       write to panic log or syslog LOG_ALERT
+              LOG_PANIC_DIE   write to panic log or LOG_ALERT and then crash
+  format    a printf() format
+  ...       arguments for format
+
+Returns:    nothing
+*/
+
+void
+log_write(unsigned int selector, int flags, const char *format, ...)
+{
+int paniclogfd;
+ssize_t written_len;
+gstring gs = { .size = LOG_BUFFER_SIZE-1, .ptr = 0, .s = log_buffer };
+gstring * g;
+va_list ap;
+
+/* If panic_recurseflag is set, we have failed to open the panic log. This is
+the ultimate disaster. First try to write the message to a debug file and/or
+stderr and also to syslog. If panic_save_buffer is not NULL, it contains the
+original log line that caused the problem. Afterwards, expire. */
+
+if (panic_recurseflag)
+  {
+  uschar *extra = panic_save_buffer ? panic_save_buffer : US"";
+  if (debug_file) debug_printf("%s%s", extra, log_buffer);
+  if (log_stderr && log_stderr != debug_file)
+    fprintf(log_stderr, "%s%s", extra, log_buffer);
+  if (*extra) write_syslog(LOG_CRIT, extra);
+  write_syslog(LOG_CRIT, log_buffer);
+  die(US"exim: could not open panic log - aborting: see message(s) above",
+    US"Unexpected log failure, please try later");
+  }
+
+/* Ensure we have a buffer (see comment above); this should never be obeyed
+when running Exim proper, only when running utilities. */
+
+if (!log_buffer)
+  if (!(log_buffer = US malloc(LOG_BUFFER_SIZE)))
+    {
+    fprintf(stderr, "exim: failed to get store for log buffer\n");
+    exim_exit(EXIT_FAILURE);
+    }
+
+/* If we haven't already done so, inspect the setting of log_file_path to
+determine whether to log to files and/or to syslog. Bits in logging_mode
+control this, and for file logging, the path must end up in file_path. This
+variable must be in permanent store because it may be required again later in
+the process. */
+
+if (!path_inspected)
+  {
+  BOOL multiple = FALSE;
+  int old_pool = store_pool;
+
+  store_pool = POOL_PERM;
+
+  /* If nothing has been set, don't waste effort... the default values for the
+  statics are file_path="" and logging_mode = LOG_MODE_FILE. */
+
+  if (*log_file_path)
+    {
+    int sep = ':';              /* Fixed separator - outside use */
+    uschar *s;
+    const uschar *ss = log_file_path;
+
+    logging_mode = 0;
+    while ((s = string_nextinlist(&ss, &sep, log_buffer, LOG_BUFFER_SIZE)))
+      {
+      if (Ustrcmp(s, "syslog") == 0)
+        logging_mode |= LOG_MODE_SYSLOG;
+      else if (logging_mode & LOG_MODE_FILE)
+	multiple = TRUE;
+      else
+        {
+        logging_mode |= LOG_MODE_FILE;
+
+        /* If a non-empty path is given, use it */
+
+        if (*s)
+          file_path = string_copy(s);
+
+        /* If the path is empty, we want to use the first non-empty, non-
+        syslog item in LOG_FILE_PATH, if there is one, since the value of
+        log_file_path may have been set at runtime. If there is no such item,
+        use the ultimate default in the spool directory. */
+
+        else
+	  set_file_path();  /* Empty item in log_file_path */
+        }    /* First non-syslog item in log_file_path */
+      }      /* Scan of log_file_path */
+    }
+
+  /* If no modes have been selected, it is a major disaster */
+
+  if (logging_mode == 0)
+    die(US"Neither syslog nor file logging set in log_file_path",
+        US"Unexpected logging failure");
+
+  /* Set up the ultimate default if necessary. Then revert to the old store
+  pool, and record that we've sorted out the path. */
+
+  if (logging_mode & LOG_MODE_FILE  &&  !file_path[0])
+    file_path = string_sprintf("%s/log/%%slog", spool_directory);
+  store_pool = old_pool;
+  path_inspected = TRUE;
+
+  /* If more than one file path was given, log a complaint. This recursive call
+  should work since we have now set up the routing. */
+
+  if (multiple)
+    log_write(0, LOG_MAIN|LOG_PANIC,
+      "More than one path given in log_file_path: using %s", file_path);
+  }
+
+/* If debugging, show all log entries, but don't show headers. Do it all
+in one go so that it doesn't get split when multi-processing. */
+
+DEBUG(D_any|D_v)
+  {
+  int i;
+
+  g = string_catn(&gs, US"LOG:", 4);
+
+  /* Show the selector that was passed into the call. */
+
+  for (i = 0; i < log_options_count; i++)
+    {
+    unsigned int bitnum = log_options[i].bit;
+    if (bitnum < BITWORDSIZE && selector == BIT(bitnum))
+      g = string_fmt_append(g, " %s", log_options[i].name);
+    }
+
+  g = string_fmt_append(g, "%s%s%s%s\n  ",
+    flags & LOG_MAIN ?    " MAIN"   : "",
+    flags & LOG_PANIC ?   " PANIC"  : "",
+    (flags & LOG_PANIC_DIE) == LOG_PANIC_DIE ? " DIE" : "",
+    flags & LOG_REJECT ?  " REJECT" : "");
+
+  if (flags & LOG_CONFIG) g = log_config_info(g, flags);
+
+  /* We want to be able to log tainted info, but log_buffer is directly
+  malloc'd.  So use deliberately taint-nonchecking routines to build into
+  it, trusting that we will never expand the results. */
+
+  va_start(ap, format);
+  i = g->ptr;
+  if (!string_vformat(g, SVFMT_TAINT_NOCHK, format, ap))
+    {
+    g->ptr = i;
+    g = string_cat(g, US"**** log string overflowed log buffer ****");
+    }
+  va_end(ap);
+
+  g->size = LOG_BUFFER_SIZE;
+  g = string_catn(g, US"\n", 1);
+  debug_printf("%s", string_from_gstring(g));
+
+  gs.size = LOG_BUFFER_SIZE-1;	/* Having used the buffer for debug output, */
+  gs.ptr = 0;			/* reset it for the real use. */
+  gs.s = log_buffer;
+  }
+/* If no log file is specified, we are in a mess. */
+
+if (!(flags & (LOG_MAIN|LOG_PANIC|LOG_REJECT)))
+  log_write(0, LOG_MAIN|LOG_PANIC_DIE, "log_write called with no log "
+    "flags set");
+
+/* There are some weird circumstances in which logging is disabled. */
+
+if (f.disable_logging)
+  {
+  DEBUG(D_any) debug_printf("log writing disabled\n");
+  if ((flags & LOG_PANIC_DIE) == LOG_PANIC_DIE) exim_exit(EXIT_FAILURE);
+  return;
+  }
+
+/* Handle disabled reject log */
+
+if (!write_rejectlog) flags &= ~LOG_REJECT;
+
+/* Create the main message in the log buffer. Do not include the message id
+when called by a utility. */
+
+g = string_fmt_append(&gs, "%s ", tod_stamp(tod_log));
+
+if (LOGGING(pid))
+  {
+  if (!syslog_pid) pid_position[0] = g->ptr;		/* remember begin … */
+  g = string_fmt_append(g, "[%d] ", (int)getpid());
+  if (!syslog_pid) pid_position[1] = g->ptr;		/*  … and end+1 of the PID */
+  }
+
+if (f.really_exim && message_id[0] != 0)
+  g = string_fmt_append(g, "%s ", message_id);
+
+if (flags & LOG_CONFIG)
+  g = log_config_info(g, flags);
+
+va_start(ap, format);
+  {
+  int i = g->ptr;
+
+  /* We want to be able to log tainted info, but log_buffer is directly
+  malloc'd.  So use deliberately taint-nonchecking routines to build into
+  it, trusting that we will never expand the results. */
+
+  if (!string_vformat(g, SVFMT_TAINT_NOCHK, format, ap))
+    {
+    g->ptr = i;
+    g = string_cat(g, US"**** log string overflowed log buffer ****\n");
+    }
+  }
+va_end(ap);
+
+/* Add the raw, unrewritten, sender to the message if required. This is done
+this way because it kind of fits with LOG_RECIPIENTS. */
+
+if (   flags & LOG_SENDER
+   && g->ptr < LOG_BUFFER_SIZE - 10 - Ustrlen(raw_sender))
+  g = string_fmt_append_f(g, SVFMT_TAINT_NOCHK, " from <%s>", raw_sender);
+
+/* Add list of recipients to the message if required; the raw list,
+before rewriting, was saved in raw_recipients. There may be none, if an ACL
+discarded them all. */
+
+if (  flags & LOG_RECIPIENTS
+   && g->ptr < LOG_BUFFER_SIZE - 6
+   && raw_recipients_count > 0)
+  {
+  int i;
+  g = string_fmt_append_f(g, SVFMT_TAINT_NOCHK, " for", NULL);
+  for (i = 0; i < raw_recipients_count; i++)
+    {
+    uschar * s = raw_recipients[i];
+    if (LOG_BUFFER_SIZE - g->ptr < Ustrlen(s) + 3) break;
+    g = string_fmt_append_f(g, SVFMT_TAINT_NOCHK, " %s", s);
+    }
+  }
+
+g = string_catn(g, US"\n", 1);
+string_from_gstring(g);
+
+/* Handle loggable errors when running a utility, or when address testing.
+Write to log_stderr unless debugging (when it will already have been written),
+or unless there is no log_stderr (expn called from daemon, for example). */
+
+if (!f.really_exim || f.log_testing_mode)
+  {
+  if (  !debug_selector
+     && log_stderr
+     && (selector == 0 || (selector & log_selector[0]) != 0)
+    )
+    if (host_checking)
+      fprintf(log_stderr, "LOG: %s", CS(log_buffer + 20));  /* no timestamp */
+    else
+      fprintf(log_stderr, "%s", CS log_buffer);
+
+  if ((flags & LOG_PANIC_DIE) == LOG_PANIC_DIE) exim_exit(EXIT_FAILURE);
+  return;
+  }
+
+/* Handle the main log. We know that either syslog or file logging (or both) is
+set up. A real file gets left open during reception or delivery once it has
+been opened, but we don't want to keep on writing to it for too long after it
+has been renamed. Therefore, do a stat() and see if the inode has changed, and
+if so, re-open. */
+
+if (  flags & LOG_MAIN
+   && (!selector ||  selector & log_selector[0]))
+  {
+  if (  logging_mode & LOG_MODE_SYSLOG
+     && (syslog_duplication || !(flags & (LOG_REJECT|LOG_PANIC))))
+    write_syslog(LOG_INFO, log_buffer);
+
+  if (logging_mode & LOG_MODE_FILE)
+    {
+    struct stat statbuf;
+
+    /* Check for a change to the mainlog file name when datestamping is in
+    operation. This happens at midnight, at which point we want to roll over
+    the file. Closing it has the desired effect. */
+
+    if (mainlog_datestamp)
+      {
+      uschar *nowstamp = tod_stamp(string_datestamp_type);
+      if (Ustrncmp (mainlog_datestamp, nowstamp, Ustrlen(nowstamp)) != 0)
+        {
+        (void)close(mainlogfd);       /* Close the file */
+        mainlogfd = -1;               /* Clear the file descriptor */
+        mainlog_inode = 0;            /* Unset the inode */
+        mainlog_datestamp = NULL;     /* Clear the datestamp */
+        }
+      }
+
+    /* Otherwise, we want to check whether the file has been renamed by a
+    cycling script. This could be "if else", but for safety's sake, leave it as
+    "if" so that renaming the log starts a new file even when datestamping is
+    happening. */
+
+    if (mainlogfd >= 0)
+      if (Ustat(mainlog_name, &statbuf) < 0 || statbuf.st_ino != mainlog_inode)
+	mainlog_close();
+
+    /* If the log is closed, open it. Then write the line. */
+
+    if (mainlogfd < 0)
+      {
+      open_log(&mainlogfd, lt_main, NULL);     /* No return on error */
+      if (fstat(mainlogfd, &statbuf) >= 0) mainlog_inode = statbuf.st_ino;
+      }
+
+    /* Failing to write to the log is disastrous */
+
+    written_len = write_to_fd_buf(mainlogfd, g->s, g->ptr);
+    if (written_len != g->ptr)
+      {
+      log_write_failed(US"main log", g->ptr, written_len);
+      /* That function does not return */
+      }
+    }
+  }
+
+/* Handle the log for rejected messages. This can be globally disabled, in
+which case the flags are altered above. If there are any header lines (i.e. if
+the rejection is happening after the DATA phase), log the recipients and the
+headers. */
+
+if (flags & LOG_REJECT)
+  {
+  if (header_list && LOGGING(rejected_header))
+    {
+    gstring * g2;
+    int i;
+
+    if (recipients_count > 0)
+      {
+      /* List the sender */
+
+      g2 = string_fmt_append_f(g, SVFMT_TAINT_NOCHK,
+			"Envelope-from: <%s>\n", sender_address);
+      if (g2) g = g2;
+
+      /* List up to 5 recipients */
+
+      g2 = string_fmt_append_f(g, SVFMT_TAINT_NOCHK,
+			"Envelope-to: <%s>\n", recipients_list[0].address);
+      if (g2) g = g2;
+
+      for (i = 1; i < recipients_count && i < 5; i++)
+        {
+        g2 = string_fmt_append_f(g, SVFMT_TAINT_NOCHK,
+			"    <%s>\n", recipients_list[i].address);
+	if (g2) g = g2;
+        }
+
+      if (i < recipients_count)
+        {
+        g2 = string_fmt_append_f(g, SVFMT_TAINT_NOCHK, "    ...\n", NULL);
+	if (g2) g = g2;
+        }
+      }
+
+    /* A header with a NULL text is an unfilled in Received: header */
+
+    for (header_line * h = header_list; h; h = h->next) if (h->text)
+      {
+      g2 = string_fmt_append_f(g, SVFMT_TAINT_NOCHK,
+			"%c %s", h->type, h->text);
+      if (g2)
+	g = g2;
+      else		/* Buffer is full; truncate */
+        {
+        g->ptr -= 100;        /* For message and separator */
+        if (g->s[g->ptr-1] == '\n') g->ptr--;
+        g = string_cat(g, US"\n*** truncated ***\n");
+        break;
+        }
+      }
+    }
+
+  /* Write to syslog or to a log file */
+
+  if (  logging_mode & LOG_MODE_SYSLOG
+     && (syslog_duplication || !(flags & LOG_PANIC)))
+    write_syslog(LOG_NOTICE, string_from_gstring(g));
+
+  /* Check for a change to the rejectlog file name when datestamping is in
+  operation. This happens at midnight, at which point we want to roll over
+  the file. Closing it has the desired effect. */
+
+  if (logging_mode & LOG_MODE_FILE)
+    {
+    struct stat statbuf;
+
+    if (rejectlog_datestamp)
+      {
+      uschar *nowstamp = tod_stamp(string_datestamp_type);
+      if (Ustrncmp (rejectlog_datestamp, nowstamp, Ustrlen(nowstamp)) != 0)
+        {
+        (void)close(rejectlogfd);       /* Close the file */
+        rejectlogfd = -1;               /* Clear the file descriptor */
+        rejectlog_inode = 0;            /* Unset the inode */
+        rejectlog_datestamp = NULL;     /* Clear the datestamp */
+        }
+      }
+
+    /* Otherwise, we want to check whether the file has been renamed by a
+    cycling script. This could be "if else", but for safety's sake, leave it as
+    "if" so that renaming the log starts a new file even when datestamping is
+    happening. */
+
+    if (rejectlogfd >= 0)
+      if (Ustat(rejectlog_name, &statbuf) < 0 ||
+           statbuf.st_ino != rejectlog_inode)
+        {
+        (void)close(rejectlogfd);
+        rejectlogfd = -1;
+        rejectlog_inode = 0;
+        }
+
+    /* Open the file if necessary, and write the data */
+
+    if (rejectlogfd < 0)
+      {
+      open_log(&rejectlogfd, lt_reject, NULL); /* No return on error */
+      if (fstat(rejectlogfd, &statbuf) >= 0) rejectlog_inode = statbuf.st_ino;
+      }
+
+    written_len = write_to_fd_buf(rejectlogfd, g->s, g->ptr);
+    if (written_len != g->ptr)
+      {
+      log_write_failed(US"reject log", g->ptr, written_len);
+      /* That function does not return */
+      }
+    }
+  }
+
+
+/* Handle the panic log, which is not kept open like the others. If it fails to
+open, there will be a recursive call to log_write(). We detect this above and
+attempt to write to the system log as a last-ditch try at telling somebody. In
+all cases except mua_wrapper, try to write to log_stderr. */
+
+if (flags & LOG_PANIC)
+  {
+  if (log_stderr && log_stderr != debug_file && !mua_wrapper)
+    fprintf(log_stderr, "%s", CS string_from_gstring(g));
+
+  if (logging_mode & LOG_MODE_SYSLOG)
+    write_syslog(LOG_ALERT, log_buffer);
+
+  /* If this panic logging was caused by a failure to open the main log,
+  the original log line is in panic_save_buffer. Make an attempt to write it. */
+
+  if (logging_mode & LOG_MODE_FILE)
+    {
+    panic_recurseflag = TRUE;
+    open_log(&paniclogfd, lt_panic, NULL);  /* Won't return on failure */
+    panic_recurseflag = FALSE;
+
+    if (panic_save_buffer)
+      {
+      int i = write(paniclogfd, panic_save_buffer, Ustrlen(panic_save_buffer));
+      i = i;	/* compiler quietening */
+      }
+
+    written_len = write_to_fd_buf(paniclogfd, g->s, g->ptr);
+    if (written_len != g->ptr)
+      {
+      int save_errno = errno;
+      write_syslog(LOG_CRIT, log_buffer);
+      sprintf(CS log_buffer, "write failed on panic log: length=%d result=%d "
+        "errno=%d (%s)", g->ptr, (int)written_len, save_errno, strerror(save_errno));
+      write_syslog(LOG_CRIT, string_from_gstring(g));
+      flags |= LOG_PANIC_DIE;
+      }
+
+    (void)close(paniclogfd);
+    }
+
+  /* Give up if the DIE flag is set */
+
+  if ((flags & LOG_PANIC_DIE) != LOG_PANIC)
+    die(NULL, US"Unexpected failure, please try later");
+  }
+}
+
+
+
+/*************************************************
+*            Close any open log files            *
+*************************************************/
+
+void
+log_close_all(void)
+{
+if (mainlogfd >= 0)
+  { (void)close(mainlogfd); mainlogfd = -1; }
+if (rejectlogfd >= 0)
+  { (void)close(rejectlogfd); rejectlogfd = -1; }
+closelog();
+syslog_open = FALSE;
+}
+
+
+
+/*************************************************
+*             Multi-bit set or clear             *
+*************************************************/
+
+/* These functions take a list of bit indexes (terminated by -1) and
+clear or set the corresponding bits in the selector.
+
+Arguments:
+  selector       address of the bit string
+  selsize        number of words in the bit string
+  bits           list of bits to set
+*/
+
+void
+bits_clear(unsigned int *selector, size_t selsize, int *bits)
+{
+for(; *bits != -1; ++bits)
+  BIT_CLEAR(selector, selsize, *bits);
+}
+
+void
+bits_set(unsigned int *selector, size_t selsize, int *bits)
+{
+for(; *bits != -1; ++bits)
+  BIT_SET(selector, selsize, *bits);
+}
+
+
+
+/*************************************************
+*         Decode bit settings for log/debug      *
+*************************************************/
+
+/* This function decodes a string containing bit settings in the form of +name
+and/or -name sequences, and sets/unsets bits in a bit string accordingly. It
+also recognizes a numeric setting of the form =<number>, but this is not
+intended for user use. It's an easy way for Exim to pass the debug settings
+when it is re-exec'ed.
+
+The option table is a list of names and bit indexes. The index -1
+means "set all bits, except for those listed in notall". The notall
+list is terminated by -1.
+
+The action taken for bad values varies depending upon why we're here.
+For log messages, or if the debugging is triggered from config, then we write
+to the log on the way out.  For debug setting triggered from the command-line,
+we treat it as an unknown option: error message to stderr and die.
+
+Arguments:
+  selector       address of the bit string
+  selsize        number of words in the bit string
+  notall         list of bits to exclude from "all"
+  string         the configured string
+  options        the table of option names
+  count          size of table
+  which          "log" or "debug"
+  flags          DEBUG_FROM_CONFIG
+
+Returns:         nothing on success - bomb out on failure
+*/
+
+void
+decode_bits(unsigned int *selector, size_t selsize, int *notall,
+  uschar *string, bit_table *options, int count, uschar *which, int flags)
+{
+uschar *errmsg;
+if (!string) return;
+
+if (*string == '=')
+  {
+  char *end;    /* Not uschar */
+  memset(selector, 0, sizeof(*selector)*selsize);
+  *selector = strtoul(CS string+1, &end, 0);
+  if (!*end) return;
+  errmsg = string_sprintf("malformed numeric %s_selector setting: %s", which,
+    string);
+  goto ERROR_RETURN;
+  }
+
+/* Handle symbolic setting */
+
+else for(;;)
+  {
+  BOOL adding;
+  uschar *s;
+  int len;
+  bit_table *start, *end;
+
+  Uskip_whitespace(&string);
+  if (!*string) return;
+
+  if (*string != '+' && *string != '-')
+    {
+    errmsg = string_sprintf("malformed %s_selector setting: "
+      "+ or - expected but found \"%s\"", which, string);
+    goto ERROR_RETURN;
+    }
+
+  adding = *string++ == '+';
+  s = string;
+  while (isalnum(*string) || *string == '_') string++;
+  len = string - s;
+
+  start = options;
+  end = options + count;
+
+  while (start < end)
+    {
+    bit_table *middle = start + (end - start)/2;
+    int c = Ustrncmp(s, middle->name, len);
+    if (c == 0)
+      if (middle->name[len] != 0) c = -1; else
+        {
+        unsigned int bit = middle->bit;
+
+	if (bit == -1)
+	  {
+	  if (adding)
+	    {
+	    memset(selector, -1, sizeof(*selector)*selsize);
+	    bits_clear(selector, selsize, notall);
+	    }
+	  else
+	    memset(selector, 0, sizeof(*selector)*selsize);
+	  }
+	else if (adding)
+	  BIT_SET(selector, selsize, bit);
+	else
+	  BIT_CLEAR(selector, selsize, bit);
+
+        break;  /* Out of loop to match selector name */
+        }
+    if (c < 0) end = middle; else start = middle + 1;
+    }  /* Loop to match selector name */
+
+  if (start >= end)
+    {
+    errmsg = string_sprintf("unknown %s_selector setting: %c%.*s", which,
+      adding? '+' : '-', len, s);
+    goto ERROR_RETURN;
+    }
+  }    /* Loop for selector names */
+
+/* Handle disasters */
+
+ERROR_RETURN:
+if (Ustrcmp(which, "debug") == 0)
+  {
+  if (flags & DEBUG_FROM_CONFIG)
+    {
+    log_write(0, LOG_CONFIG|LOG_PANIC, "%s", errmsg);
+    return;
+    }
+  fprintf(stderr, "exim: %s\n", errmsg);
+  exit(EXIT_FAILURE);
+  }
+else log_write(0, LOG_CONFIG|LOG_PANIC_DIE, "%s", errmsg);
+}
+
+
+
+/*************************************************
+*        Activate a debug logfile (late)         *
+*************************************************/
+
+/* Normally, debugging is activated from the command-line; it may be useful
+within the configuration to activate debugging later, based on certain
+conditions.  If debugging is already in progress, we return early, no action
+taken (besides debug-logging that we wanted debug-logging).
+
+Failures in options are not fatal but will result in paniclog entries for the
+misconfiguration.
+
+The first use of this is in ACL logic, "control = debug/tag=foo/opts=+expand"
+which can be combined with conditions, etc, to activate extra logging only
+for certain sources. The second use is inetd wait mode debug preservation. */
+
+void
+debug_logging_activate(uschar *tag_name, uschar *opts)
+{
+int fd = -1;
+
+if (debug_file)
+  {
+  debug_printf("DEBUGGING ACTIVATED FROM WITHIN CONFIG.\n"
+      "DEBUG: Tag=\"%s\" opts=\"%s\"\n", tag_name, opts ? opts : US"");
+  return;
+  }
+
+if (tag_name != NULL && (Ustrchr(tag_name, '/') != NULL))
+  {
+  log_write(0, LOG_MAIN|LOG_PANIC, "debug tag may not contain a '/' in: %s",
+      tag_name);
+  return;
+  }
+
+debug_selector = D_default;
+if (opts)
+  decode_bits(&debug_selector, 1, debug_notall, opts,
+      debug_options, debug_options_count, US"debug", DEBUG_FROM_CONFIG);
+
+/* When activating from a transport process we may never have logged at all
+resulting in certain setup not having been done.  Hack this for now so we
+do not segfault; note that nondefault log locations will not work */
+
+if (!*file_path) set_file_path();
+
+open_log(&fd, lt_debug, tag_name);
+
+if (fd != -1)
+  debug_file = fdopen(fd, "w");
+else
+  log_write(0, LOG_MAIN|LOG_PANIC, "unable to open debug log");
+}
+
+
+void
+debug_logging_stop(void)
+{
+if (!debug_file || !debuglog_name[0]) return;
+
+debug_selector = 0;
+fclose(debug_file);
+debug_file = NULL;
+unlink_log(lt_debug);
+}
+
+
+/* End of log.c */