https://github.com/katef/liblf
Apache LogFormat log format format parsing library
https://github.com/katef/liblf
apache apache-httpd fmtstring logfmt logfmt-parser logformat logs parser parser-library
Last synced: 3 months ago
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Apache LogFormat log format format parsing library
- Host: GitHub
- URL: https://github.com/katef/liblf
- Owner: katef
- License: bsd-2-clause
- Created: 2017-09-20T01:48:06.000Z (almost 8 years ago)
- Default Branch: main
- Last Pushed: 2022-05-16T04:15:20.000Z (about 3 years ago)
- Last Synced: 2025-01-24T23:43:07.965Z (5 months ago)
- Topics: apache, apache-httpd, fmtstring, logfmt, logfmt-parser, logformat, logs, parser, parser-library
- Language: C
- Homepage:
- Size: 59.6 KB
- Stars: 2
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
## liblf: A parser for the syntax used by Apache's LogFormat Directive
The LogFormat directive provides a printf-like syntax for specifying
user-defined custom formats for log messages. It's intended for logs
about HTTP traffic, and includes formatting for IP addresses, response
status, and other relevant things.
There's an [EBNF grammar for the syntax](doc/logfmt.ebnf).
[Apache's documentation](https://httpd.apache.org/docs/current/mod/mod_log_config.html#formats)
is the authoritative reference for the various format directives.
## What would I use it for?
Maybe you're writing a daemon that serves requests (not necessarily HTTP)
and you'd like to give your users a familiar-feeling syntax for
configuring what to log. Or perhaps you're writing a tool to convert
Apache configurations to another system.
You can disable the directives you don't need, and add custom ones.
## How do I use it?
This library aims to provide a complete implementation, presenting an
API independent of any particular source for data, and of any particular
output. The entry point is lf_parse(), which calls various callbacks as
it parses each part of the format string. See [](include/lf/lf.h)
for the API.
* As a parser: Have your callbacks store the data,
and act on it later.
* As an interpreter: Parse log format strings whilst serving a request,
and have your callbacks output the relevant items immediately.
* As a compiler: Parse log format strings ahead of time, and output
generated code.
There's an example program which just prints out directives as they come.
You get pretty decent error messages:
```
; lfdump '%{}e %v %h %l %u %t \"%r\" %>s %b %{user-agent}i'
error: Empty name
at 1: '%{}e %v %h %l %u %t \"%r\" %>s %b %{user-agent}i'
--------^^
```
Related projects:
* This C library is an independent implementation, and uses no code from
[Apache's original implementation](https://github.com/apache/httpd/blob/trunk/modules/loggers/mod_log_config.c).
* Kazeburo's [Apache::LogFormat::Compiler](https://github.com/kazeburo/Apache-LogFormat-Compiler),
the inspiration for this project.
* Miyagawa's [port of Apache::LogFormat::Compiler to Go](https://github.com/miyagawa/go-apache-logformat).
Clone with submodules (contains required .mk files):
; git clone --recursive https://github.com/katef/liblf.git
To build and install:
; pmake -r install
You can override a few things:
; CC=clang PREFIX=$HOME pmake -r install
Building depends on:
* Any BSD make. This includes OpenBSD, FreeBSD and NetBSD make(1)
and sjg's portable bmake (also packaged as pmake).
* A C compiler. Any should do, but GCC and clang are best supported.
* ar, ld, and a bunch of other stuff you probably already have.
Fuzzing depends on:
* [Radamsa](https://gitlab.com/akihe/radamsa)
* [Blab](https://github.com/aoh/blab)
* [KGT](https://github.com/katef/kgt)
```
; pmake -r CC=gcc DEBUG=1 && pmake VERBOSE=1 -r fuzz
```
Ideas, comments or bugs: [email protected]