Syslog

The syslog package provides a Ruby interface to the POSIX system logging facility.

Syslog messages are typically passed to a central logging daemon. The daemon may filter them; route them into different files (usually found under /var/log); place them in SQL databases; forward them to centralized logging servers via TCP or UDP; or even alert the system administrator via email, pager or text message.

Unlike application-level logging via Logger or Log4r, syslog is designed to allow secure tamper-proof logging.

The syslog protocol is standardized in RFC 5424.

Public Class Methods

LOG_MASK(priority_level) => priority_mask click to toggle source

Generates a mask bit for a priority level. See mask=

                
static VALUE mSyslogConstants_LOG_MASK(VALUE klass, VALUE pri)
{
    return INT2FIX(LOG_MASK(NUM2INT(pri)));
}

LOG_UPTO(priority_level) => priority_mask click to toggle source

Generates a mask value for priority levels at or below the level specified. See mask=

                
static VALUE mSyslogConstants_LOG_UPTO(VALUE klass, VALUE pri)
{
    return INT2FIX(LOG_UPTO(NUM2INT(pri)));
}

close() click to toggle source

Closes the syslog facility. Raises a runtime exception if it is not open.

                
static VALUE mSyslog_close(VALUE self)
{
    rb_secure(4);
    if (!syslog_opened) {
        rb_raise(rb_eRuntimeError, "syslog not opened");
    }

    closelog();

    free((void *)syslog_ident);
    syslog_ident = NULL;
    syslog_options = syslog_facility = syslog_mask = -1;
    syslog_opened = 0;

    return Qnil;
}

facility() click to toggle source

Returns the facility number used in the last call to open()

                
static VALUE mSyslog_facility(VALUE self)
{
    return syslog_opened ? INT2NUM(syslog_facility) : Qnil;
}

ident() click to toggle source

Returns the identity string used in the last call to open()

                
static VALUE mSyslog_ident(VALUE self)
{
    return syslog_opened ? rb_str_new2(syslog_ident) : Qnil;
}

inspect() click to toggle source

Returns an inspect() string summarizing the object state.

                
static VALUE mSyslog_inspect(VALUE self)
{
    char buf[1024];

    if (syslog_opened) {
        snprintf(buf, sizeof(buf),
          "<#%s: opened=true, ident=\"%s\", options=%d, facility=%d, mask=%d>",
          rb_class2name(self),
          syslog_ident,
          syslog_options,
          syslog_facility,
          syslog_mask);
    } else {
        snprintf(buf, sizeof(buf),
          "<#%s: opened=false>", rb_class2name(self));
    }

    return rb_str_new2(buf);
}

instance() click to toggle source

Returns self, for backward compatibility.

                
static VALUE mSyslog_instance(VALUE self)
{
    return self;
}

log(priority, format_string, *format_args) click to toggle source

Log a message with the specified priority. Example:

Syslog.log(Syslog::LOG_CRIT, "Out of disk space")
Syslog.log(Syslog::LOG_CRIT, "User %s logged in", ENV['USER'])

The priority levels, in descending order, are:

LOG_EMERG	System is unusable
LOG_ALERT	Action needs to be taken immediately
LOG_CRIT	A critical condition has occurred
LOG_ERR	An error occurred
LOG_WARNING	Warning of a possible problem
LOG_NOTICE	A normal but significant condition occurred
LOG_INFO	Informational message
LOG_DEBUG	Debugging information

Each priority level also has a shortcut method that logs with it’s named priority. As an example, the two following statements would produce the same result:

Syslog.log(Syslog::LOG_ALERT, "Out of memory")
Syslog.alert("Out of memory")

Format strings are as for printf/sprintf, except that in addition %m is replaced with the error message string that would be returned by strerror(errno).

                
static VALUE mSyslog_log(int argc, VALUE *argv, VALUE self)
{
    VALUE pri;

    if (argc < 2) {
        rb_raise(rb_eArgError, "wrong number of arguments (%d for 2+)", argc);
    }

    argc--;
    pri = *argv++;

    if (!FIXNUM_P(pri)) {
      rb_raise(rb_eTypeError, "type mismatch: %s given", rb_class2name(CLASS_OF(pri)));
    }

    syslog_write(FIX2INT(pri), argc, argv);

    return self;
}

mask() click to toggle source

Returns the log priority mask in effect. The mask is not reset by opening or closing syslog.

                
static VALUE mSyslog_get_mask(VALUE self)
{
    return syslog_opened ? INT2NUM(syslog_mask) : Qnil;
}

mask=(priority_mask) click to toggle source

Sets the log priority mask. A method LOG_UPTO is defined to make it easier to set mask values. Example:

Syslog.mask = Syslog::LOG_UPTO(Syslog::LOG_ERR)

Alternatively, specific priorities can be selected and added together using binary OR. Example:

Syslog.mask = Syslog::LOG_MASK(Syslog::LOG_ERR) | Syslog::LOG_MASK(Syslog::LOG_CRIT)

The priority mask persists through calls to open() and close().

                
static VALUE mSyslog_set_mask(VALUE self, VALUE mask)
{
    rb_secure(4);
    if (!syslog_opened) {
        rb_raise(rb_eRuntimeError, "must open syslog before setting log mask");
    }

    setlogmask(syslog_mask = NUM2INT(mask));

    return mask;
}

open(ident, options, facility) => syslog click to toggle source

Open the syslog facility. Raises a runtime exception if it is already open.

Can be called with or without a code block. If called with a block, the Syslog object created is passed to the block.

If the syslog is already open, raises a RuntimeError.

ident is a String which identifies the calling program.

options is the logical OR of any of the following:

LOG_CONS	If there is an error while sending to the system logger, write directly to the console instead.
LOG_NDELAY	Open the connection now, rather than waiting for the first message to be written.
LOG_NOWAIT	Don’t wait for any child processes created while logging messages. (Has no effect on Linux.)
LOG_ODELAY	Opposite of LOG_NDELAY; wait until a message is sent before opening the connection. (This is the default.)
LOG_PERROR	Print the message to stderr as well as sending it to syslog. (Not in POSIX.1-2001.)
LOG_PID	Include the current process ID with each message.

facility describes the type of program opening the syslog, and is the logical OR of any of the following which are defined for the host OS:

LOG_AUTH	Security or authorization. Deprecated, use LOG_AUTHPRIV instead.
LOG_AUTHPRIV	Security or authorization messages which should be kept private.
LOG_CONSOLE	System console message.
LOG_CRON	System task scheduler (cron or at).
LOG_DAEMON	A system daemon which has no facility value of its own.
LOG_FTP	An FTP server.
LOG_KERN	A kernel message (not sendable by user processes, so not of much use to Ruby, but listed here for completeness).
LOG_LRP	Line printer subsystem.
LOG_MAIL	Mail delivery or transport subsystem.
LOG_NEWS	Usenet news system.
LOG_NTP	Network Time Protocol server.
LOG_SECURITY	General security message.
LOG_SYSLOG	Messages generated internally by syslog.
LOG_USER	Generic user-level message.
LOG_UUCP	UUCP subsystem.
LOG_LOCAL0 to LOG_LOCAL7	Locally-defined facilities.

Example:

Syslog.open("webrick", Syslog::LOG_PID,
            Syslog::LOG_DAEMON | Syslog::LOG_LOCAL3)

                
static VALUE mSyslog_open(int argc, VALUE *argv, VALUE self)
{
    VALUE ident, opt, fac;

    if (syslog_opened) {
        rb_raise(rb_eRuntimeError, "syslog already open");
    }

    rb_scan_args(argc, argv, "03", &ident, &opt, &fac);

    if (NIL_P(ident)) {
        ident = rb_gv_get("$0");
    }
    SafeStringValue(ident);
    syslog_ident = strdup(RSTRING_PTR(ident));

    if (NIL_P(opt)) {
        syslog_options = LOG_PID | LOG_CONS;
    } else {
        syslog_options = NUM2INT(opt);
    }

    if (NIL_P(fac)) {
        syslog_facility = LOG_USER;
    } else {
        syslog_facility = NUM2INT(fac);
    }

    openlog(syslog_ident, syslog_options, syslog_facility);

    syslog_opened = 1;

    setlogmask(syslog_mask = setlogmask(0));

    /* be like File.new.open {...} */
    if (rb_block_given_p()) {
        rb_ensure(rb_yield, self, mSyslog_close, self);
    }

    return self;
}

reopen(ident, options, facility) => syslog click to toggle source

Closes and then reopens the syslog.

Arguments are the same as for open().

                
static VALUE mSyslog_reopen(int argc, VALUE *argv, VALUE self)
{
    mSyslog_close(self);

    return mSyslog_open(argc, argv, self);
}

opened? click to toggle source

Returns true if the syslog is open.

                
static VALUE mSyslog_isopen(VALUE self)
{
    return syslog_opened ? Qtrue : Qfalse;
}

options() click to toggle source

Returns the options bitmask used in the last call to open()

                
static VALUE mSyslog_options(VALUE self)
{
    return syslog_opened ? INT2NUM(syslog_options) : Qnil;
}

reopen(ident, options, facility) => syslog click to toggle source

Closes and then reopens the syslog.

Arguments are the same as for open().

                
static VALUE mSyslog_reopen(int argc, VALUE *argv, VALUE self)
{
    mSyslog_close(self);

    return mSyslog_open(argc, argv, self);
}

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