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diff --git a/doc/rscript_abnf.html b/doc/rscript_abnf.html new file mode 100644 index 00000000..9172d945 --- /dev/null +++ b/doc/rscript_abnf.html @@ -0,0 +1,94 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> +<html><head> +<meta http-equiv="Content-Language" content="en"><title>RainerScript ABNF</title></head> +<body> +<h1>RainerScript ABNF</h1> +<p>This is the formal definition of RainerScript, as supported by +rsyslog configuration. Please note that this currently is working +document and the actual implementation may be quite different.</p> +<p>The +first glimpse of RainerScript will be available as part of rsyslog +3.12.0 expression support. However, the 3.12. series of rsyslog will +have a partial script implementaiton, which will not necessariy be +compatible with the later full implementation. So if you use it, be +prepared for some config file changes as RainerScript evolves.</p> +<p>C-like comments (/* some comment */) are supported in all pure +RainerScript lines. However, legacy-mapped lines do not support them. +All lines support the hash mark "#" as a comment initiator. Everything +between the hash and the end of line is a comment (just like // in C++ +and many other languages).</p> +<h2>Formal Definition</h2> +<p>Below is the formal language definitionin ABNF (RFC 2234) +format: <br> +</p> +<pre>; <span style="font-weight: bold;">all of this is a working document and may change!</span> -- rgerhards, 2008-02-24<br> +<br> +script := *stmt<br> +stmt := (if_stmt / block / vardef / run_s / load_s)<br> +vardef := "var" ["scope" = ("global" / "event")] <br> +block := "begin" stmt "end"<br> +load_s := "load" constraint ("module") modpath params ; load mod only if expr is true<br> +run_s := "run" constraint ("input") name<br> +constraint:= "if" expr ; constrains some one-time commands<br> +modpath := expr<br> +params := ["params" *1param *("," param) "endparams"]<br> +param := paramname) "=" expr<br> +paramname := [*(obqualifier ".") name]<br> +modpath:= ; path to module<br> +?line? := cfsysline / cfli<br> +cfsysline:= BOL "$" *char EOL ; how to handle the first line? (no EOL in front!)<br> +BOL := ; Begin of Line - implicitely set on file beginning and after each EOL<br> +EOL := 0x0a ;LF<br> +if_stmt := "if" expr "then"<br> +old_filter:= BOL facility "." severity ; no whitespace allowed between BOL and facility!<br> +facility := "*" / "auth" / "authpriv" / "cron" / "daemon" / "kern" / "lpr" / <br> +"mail" / "mark" / "news" / "security" / "syslog" / "user" / "uucp" / <br> +"local0" .. "local7" / "mark"<br> +; The keyword security should not be used anymore<br> +; mark is just internal<br> +severity := TBD ; not really relevant in this context<br> +<br> +; and now the actual expression<br> +expr := e_and *("or" e_and)<br> +e_and := e_cmp *("and" e_cmp)<br> +e_cmp := val 0*1(cmp_op val)<br> +val := term *(("+" / "-" / "&") term)<br> +term := factor *(("*" / "/" / "%") factor)<br> +factor := ["not"] ["-"] terminal<br> +terminal := var / constant / function / ( "(" expr ")" )<br> +function := name "(" *("," expr) ")"<br> +var := "$" varname<br> +varname := msgvar / sysvar / ceevar<br> +msgvar := name<br> +ceevar := "!" name<br> +sysvar := "$" name<br> +name := alpha *(alnum)<br> +constant := string / number<br> +string := simpstr / tplstr ; tplstr will be implemented in next phase<br> +simpstr := "'" *char "'" ; use your imagination for char ;)<br> +tplstr := '"' template '"' ; not initially implemented<br> +number := ["-"] 1*digit ; 0nn = octal, 0xnn = hex, nn = decimal<br> +cmp_op := "==" / "!=" / "<>" / "<" / ">" / "<=" / ">=" / "contains" / "contains_i" / "startswith" / "startswith_i"<br> +digit := %x30-39<br> +alpha := "a" ... "z" # all letters<br> +alnum :* alpha / digit / "_" /"-" # "-" necessary to cover currently-existing message properties<br> +</pre> +<h2>Samples</h2> +<p>Some samples of RainerScript:</p><p>define function IsLinux<br>begin<br> if $environ contains "linux" then return true else return false<br>end</p><p>load if IsLinux() 'imklog.so' params name='klog' endparams /* load klog under linux only */<br>run if IsLinux() input 'klog'<br>load 'ommysql.so'</p><p>if $message contains "error" then<br> action<br> type='ommysql.so', queue.mode='disk', queue.highwatermark = 300,<br> action.dbname='events', action.dbuser='uid',<br> + [?action.template='templatename'?] or [?action.sql='insert into +table... values('&$facility&','&$severity&...?]<br> endaction<br><br>... or ...</p><p>define action writeMySQL<br> type='ommysql.so', queue.mode='disk', queue.highwatermark = 300,<br> action.dbname='events', action.dbuser='uid',<br> [?action.template='templatename'?] or [?action.sql='insert into table... values('<span style="font-family: monospace;"> &</span> $facility & ',' & $severity &...?]<br> endaction</p><p>if $message contains "error" then action writeMySQL</p><p>ALTERNATE APPROACH</p><p>define function IsLinux(<br> if $environ contains "linux" then return true else return false<br>)</p><p>load if IsLinux() 'imklog.so' params name='klog' endparams /* load klog under linux only */<br>run if IsLinux() input 'klog'<br>load 'ommysql.so'</p><p>if $message contains "error" then<br> action(<br> type='ommysql.so', queue.mode='disk', queue.highwatermark = 300,<br> action.dbname='events', action.dbuser='uid',<br> + [?action.template='templatename'?] or [?action.sql='insert into +table... values('&$facility&','&$severity&...?]<br> )<br><br>... or ...</p><p>define action writeMySQL(<br> type='ommysql.so', queue.mode='disk', queue.highwatermark = 300,<br> action.dbname='events', action.dbuser='uid',<br> + [?action.template='templatename'?] or [?action.sql='insert into +table... values('&$facility&','&$severity&...?]<br> )</p><p>if $message contains "error" then action writeMySQL(action.dbname='differentDB')</p><p></p><p>[<a href="rsyslog_conf.html">rsyslog.conf overview</a>] +<h2>Implementation</h2> +RainerScript will be implemented via a hand-crafted LL(1) parser. I was tempted to use yacc, but it turned out the resulting code was not thread-safe and as such did not fit within the context of rsyslog. Also, limited error handling is not a real problem for us: if there is a problem in parsing the configuration file, we stop processing. Guessing what was meant and trying to recover would IMHO not be good choices for something like a syslogd. +[<a href="manual.html">manual index</a>] [<a href="http://www.rsyslog.com/">rsyslog site</a>]</p> +<p><font size="2">This documentation is part of the +<a href="http://www.rsyslog.com/">rsyslog</a> +project.<br> +Copyright © 2008 by <a href="http://www.gerhards.net/rainer">Rainer +Gerhards</a> and +<a href="http://www.adiscon.com/">Adiscon</a>. +Released under the GNU GPL version 3 or higher.</font></p> +</body></html> |