wordsplit/README

README file for the wordsplit library
See the end of file for copying conditions.

* Overview

This package provides a set of C functions for parsing input strings.
Default parsing rules are similar to those used in Bourne shell.
This includes tilde expansion, variable expansion, quote removal, word
splitting, command substitution, and path expansion.  Parsing is
controlled by a number of settings which allow the caller to alter
processing at each of these phases or even to disable any of them.
Thus, wordsplit can be used for parsing inputs in different formats,
from simple character-delimited entries, as in /etc/passwd, and up to
complex shell statements.

The following code fragment shows the basic usage:

   /* This variable controls parsing */
   wordsplit_t ws;
   int rc;

   /* Provide variable definitions */
   ws.ws_env = (const char **) environ;
   /* Provide a function for expanding commands */
   ws.ws_command = runcom;
   /* Split input_string into words */
   rc = wordsplit(input_string, &ws,
		  WRDSF_QUOTE     /* Handle both single and
				     double quoted strings as words. */
		  | WRDSF_SQUEEZE_DELIMS /* Compress adjacent delimiters */
		  | WRDSF_PATHEXPAND     /* Expand pathnames */
		  | WRDSF_SHOWERR);      /* Show errors */
   if (rc == 0) {
       /* Success.  The resulting words are returned in the NULL-terminated
	  array ws.ws_wordv.  Number of words is in ws.ws_wordc */
   }
   /* Reclaim the allocated memory */
   wordsplit_free(&ws);

For a detailed discussion, please see the man page wordsplit.3 included
in the package.

* Description

The package is designed as a drop-in facility for use in larger
programs.  It consists of the following files:

  wordsplit.h   - Interface header.
  wordsplit.c   - Main source file.
  wordsplit.3   - Documentation.

For most uses, you will need only these three.  The remaining files
are for building the autotest-based testsuite:

  wsp.c         - Auxiliary test program.
  wordsplit.at  - The source for the testsuite.

* Incorporating wordsplit into your project

Wordsplit is designed to be used as a git submodule.  To incorporate
it into your project, first select the location for the wordsplit
directory within your project.  Then add the submodule at this
location.  The rest is quite straightforward: you need to add
wordsplit.c to your sources and add both wordsplit.c and wordsplit.h
to the distributed files.

The following will describe each step in detail.  For the rest of this
discussion it is supposed that 'wordsplit' is the name of the location
selected for the submodule.  It is also supposed that your project
uses GNU autotools framework.  If you are using plain makefiles, these
instructions are easy to convert to such use as well.

To add the submodule do:

  git submodule add git://git.gnu.org.ua/wordsplit.git wordsplit

There are two methods of including the sources to the project: direct
incorporation and incorporation via VPATH.

** Direct incorporation

Add the subdir-objects option to the invocation of AM_INIT_AUTOMAKE macro in
your configure.ac:

  AM_INIT_AUTOMAKE([subdir-objects])

In your Makefile.am, add both wordsplit/wordsplit.c and wordsplit/wordsplit.h
to the sources and -Iwordsplit to the cpp flags.  For example:

  program_SOURCES = main.c \
		    wordsplit/wordsplit.c \
		    wordsplit/wordsplit.h
  AM_CPPFLAGS = -I$(srcdir)/wordsplit

You can also put wordsplit.h in the noinst_HEADERS variable, if you like:

  program_SOURCES = main.c \
		    wordsplit/wordsplit.c
  noinst_HEADERS = wordsplit/wordsplit.h
  AM_CPPFLAGS = -I$(srcdir)/wordsplit

If you are building an installable library and wish to export the
wordsplit API, install wordsplit.h to $(pkgincludedir), e.g.

  lib_LTLIBRARIES = libmy.la
  libmy_la_SOURCES = main.c \
		     wordsplit/wordsplit.c
  AM_CPPFLAGS = -I$(srcdir)/wordsplit
  pkginclude_HEADERS = wordsplit/wordsplit.h

** VPATH-based incorporation

Modify the VPATH variable in your Makefile.am:

  VPATH = $(srcdir):$(srcdir)/wordsplit

Add wordsplit.c to the nodist_program_SOURCES variable:

  nodist_program_SOURCES = wordsplit.c

The nodist_ prefix is necessary to prevent Make from trying to
distribute this file from the current directory (where it doesn't
exist, of course).  During compilation it will be located using VPATH.

Finally, add both wordsplit/wordsplit.c and wordsplit/wordsplit.h to
the EXTRA_DIST variable and modify AM_CPPFLAGS as shown in the
previous section.

An example Makefile.am:

  program_SOURCES = main.c
  nodist_program_SOURCES = wordsplit.c
  VPATH = $(srcdir):$(srcdir)/wordsplit
  EXTRA_DIST = wordsplit/wordsplit.c wordsplit/wordsplit.h
  AM_CPPFLAGS = -I$(srcdir)/wordsplit

It is also possible to use LDADD as shown in the example below:

  program_SOURCES = main.c
  LDADD = wordsplit.o
  VPATH = $(srcdir):$(srcdir)/wordsplit
  EXTRA_DIST = wordsplit/wordsplit.c wordsplit/wordsplit.h
  AM_CPPFLAGS = -I$(srcdir)/wordsplit

* The testsuite

The package contains two files for building the testsuite: wsp.c,
which is used to build the auxiliary binary wsp, and wordsplit.at,
which can be included to a GNU autotest-based testsuite source.

The discussion below is for those who wish to include wordsplit
testsuite into their project.  It assumes that the hosting project
already has an autotest-based testsuite.

** Additional files

To build the auxiliary tool wsp, it is recommended to define the
WORDSPLIT_VERSION macro to the actual version of the wordsplit
package.  There are two ways of doing so.  First, you can define
WORDSPLIT_VERSION in your config.h or pass its definition via the
AM_CPPFLAGS variable.  Secondly, you can create an additional file,
wordsplit-version.h, containing its definition and define the
HAVE_WORDSPLIT_VERSION_H macro to make sure it is included.  The
following shell fragment can be used to create the header:

  version=$(cd wordsplit; git describe)
  cat > wordsplit-version.h <<EOF
  #define WORDSPLIT_VERSION "$version"
  EOF

This file should be listed in the EXTRA_DIST variable to make sure
it is distributed with the tarball.

** testsuite.at

Include the file wordsplit.at to your testsuite.at:

  m4_include(wordsplit.at)

** Makefile.am

In the Makefile.am responsible for creating the testsuite, make sure
that the path to the wordsplit module is passed to the autotest
invocation, so that the above m4_include statement will work.  The
usual make goal to build the testsuite looks as follows:

  $(TESTSUITE): package.m4 $(TESTSUITE_AT)
	$(AM_V_GEN)$(AUTOTEST) \
	      -I $(srcdir)\
	      -I $(top_srcdir)/wordsplit\
	      testsuite.at -o $@.tmp
	$(AM_V_at)mv $@.tmp $@

Then, add the following fragment to build the auxiliary files:

  # ###########################
  # Wordsplit testsuite
  # ###########################
  EXTRA_DIST += wordsplit-version.h
  $(srcdir)/wordsplit-version.h: $(top_srcdir)/configure.ac
	$(AM_V_GEN){\
	  if test -e $(top_srcdir)/libmailutils/wordsplit/.git; then \
	      wsversion=$$(cd $(top_srcdir)/libmailutils/wordsplit; git describe); \
	  else \
	      wsversion="unknown"; \
	  fi;\
	  echo "#define WORDSPLIT_VERSION \"$$wsversion\""; } > \
	 > $(srcdir)/wordsplit-version.h

  AM_CPPFLAGS += -DHAVE_WORDSPLIT_VERSION_H
  noinst_PROGRAMS += wsp
  wsp_SOURCES =
  nodist_wsp_SOURCES = wsp.c
  wsp.o: $(srcdir)/wordsplit-version.h
  VPATH = $(srcdir):$(top_srcdir)/wordsplit

* History

First version of wordsplit appeared in March 2009 as part of the
Wydawca[1] project.  Its main usage was to assist in configuration
file parsing.  The parser subsystem proved to be quite useful and
soon evolved into a separate project - Grecs[2].  This package had been
since used (as a git submodule) in a number of other projects, such as
GNU Dico[3] and Direvent[4], to name a few.

In 2010 wordsplit sources were incorporated to the GNU Mailutils[5]
package, where they replaced the obsolete argcv module.  Mailutils
uses its own configuration package, which meant that using Grecs was
not expedient.  Therefore the sources had been exported from
Grecs. Since then both Mailutils and Grecs versions were periodically
synchronized.

Several other projects, such as GNU Rush[6] and fileserv[7], followed
suit.  It was therefore decided that it would be advisable to
have wordsplit as a separate package which could be easily included in
another project without incurring unnecessary overhead.

By the end of July 2019, all mentioned packages switched to using
wordsplit as a submodule.

* References

[1] Wydawca - an automatic release submission daemon
    Home: <http://puszcza.gnu.org.ua/software/wydawca>
    Git: <http://git.gnu.org.ua/cgit/wydawca.git>
[2] Grecs - a library for parsing structured configuration files
    Home: <https://puszcza.gnu.org.ua/projects/grecs>
    Git: <http://git.gnu.org.ua/cgit/grecs.git>
[3] GNU Dico - a dictionary server
    Home: <https://puszcza.gnu.org.ua/projects/dico>
    Git: <http://git.gnu.org.ua/cgit/dico.git>
[4] GNU Direvent - filesystem event watching daemon
    Home: <http://puszcza.gnu.org.ua/software/direvent>
    Git: <http://git.gnu.org.ua/cgit/direvent.git>
[5] GNU Mailutils - a general-purpose mail package
    Home: <http://mailutils.org>
    Git: <http://git.savannah.gnu.org/cgit/mailutils.git>
[6] GNU Rush - a restricted user shell for remote access
    Home: <http://puszcza.gnu.org.ua/software/rush>
    Git: <http://git.gnu.org.ua/cgit/rush.git>
[7] fileserv - simple http server for serving static files
    Home: <https://puszcza.gnu.org.ua/projects/fileserv>
    Git: <http://git.gnu.org.ua/cgit/fileserv.git>
[8] vmod-dbrw -	Database-driven rewrite rules for Varnish Cache
    Home: <http://puszcza.gnu.org.ua/software/vmod-dbrw>
    Git: <http://git.gnu.org.ua/cgit/vmod-dbrw.git>

* Bug reporting

Please send bug reports, questions, suggestions and criticism to
<gray@gnu.org>.  When sending bug reports, please make sure to provide
the following information:

  1. Wordsplit invocation flags.
  2. Input string.
  3. Produced output.
  4. Expected output.

* Copying

Copyright (C) 2009-2025 Sergey Poznyakoff

Permission is granted to anyone to make or distribute verbatim copies
of this document as received, in any medium, provided that the
copyright notice and this permission notice are preserved,
thus giving the recipient permission to redistribute in turn.

Permission is granted to distribute modified versions
of this document, or of portions of it, under the above conditions,
provided also that they carry prominent notices stating who last
changed them.

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