.\" Copyright (c) 2013-2014 Devin Teske <dteske@FreeBSD.org>
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd Oct 24, 2014
.Dt FIGPAR 3
.Os
.Sh NAME
.Nm figpar ,
.Nm parse_config ,
.Nm get_config_option
.Nd configuration file parsing library
.Sh LIBRARY
.Lb libfigpar
.Sh SYNOPSIS
.In figpar.h
.Ft int
.Fo parse_config
.Fa "struct fp_config options[], const char *path"
.Fa "int \*[lp]*unknown\*[rp]\*[lp]struct fp_config *option, uint32_t line"
.Fa "char *directive, char *value\*[rp], uint8_t processing_options"
.Fc
.Ft "struct fp_config *"
.Fo get_config_option
.Fa "struct fp_config options[], const char *directive"
.Fc
.In string_m.h
.Ft int
.Fo replaceall
.Fa "char *source, const char *find, const char *replace"
.Fc
.Ft unsigned int
.Fo strcount
.Fa "const char *source, const char *find"
.Fc
.Ft void
.Fo strexpand
.Fa "char *source"
.Fc
.Ft void
.Fo strexpandnl
.Fa "char *source"
.Fc
.Ft void
.Fo strtolower
.Fa "char *source"
.Fc
.Sh DESCRIPTION
The
.Nm
library provides a light-weight, portable framework for parsing configuration
files.
The library uses
.Xr open 2 ,
.Xr read 2 ,
and
.Xr lseek 2
within the file pointed to by
.Fa path
to find directives and values which are then made available to the application.
.Pp
Due to the fact that configuration files may have basic syntax differences,
the library does not attempt to impose any structure on the data but instead
provides raw data to a set of callback functions.
These callback functions can in-turn initiate abort through their return value,
allowing custom syntax validation during parsing.
.Pp
Configuration directives, types, and callback functions are provided through
data structures defined in
.In figpar.h :
.Bd -literal -offset indent
struct fp_config {
    enum fp_cfgtype	type;		/* value type */
    const char		*directive;	/* keyword */
    union fp_cfgvalue	value;		/* value */

    /* Pointer to function used when directive is found */
    int (*action)(struct fp_config *option, uint32_t line,
        char *directive, char *value);
};

enum fp_cfgtype {
    FP_TYPE_NONE      = 0x0000, /* for directives with no value */
    FP_TYPE_BOOL      = 0x0001, /* boolean */
    FP_TYPE_INT       = 0x0002, /* signed 32 bit integer */
    FP_TYPE_UINT      = 0x0004, /* unsigned 32 bit integer */
    FP_TYPE_STR       = 0x0008, /* string pointer */
    FP_TYPE_STRARRAY  = 0x0010, /* string array pointer */
    FP_TYPE_DATA1     = 0x0020, /* void data type-1 (whatever) */
    FP_TYPE_DATA2     = 0x0040, /* void data type-2 (whatever) */
    FP_TYPE_DATA3     = 0x0080, /* void data type-3 (whatever) */
    FP_TYPE_RESERVED1 = 0x0100, /* reserved data type-1 (future) */
    FP_TYPE_RESERVED2 = 0x0200, /* reserved data type-2 (future) */
    FP_TYPE_RESERVED3 = 0x0400, /* reserved data type-3 (future) */
};

union fp_cfgvalue {
    void	*data;      /* Pointer to NUL-terminated string */
    char	*str;       /* Pointer to NUL-terminated string */
    char	**strarray; /* Pointer to an array of strings */
    int32_t	num;        /* Signed 32-bit integer value */
    uint32_t	u_num;      /* Unsigned 32-bit integer value */
    uint32_t	boolean:1;  /* Boolean integer value (0 or 1) */
};
.Ed
.Pp
The
.Fa processing_options
argument to
.Fn parse_config
is a mask of bit fields which indicate various
processing options.
The possible flags are as follows:
.Bl -tag -width FP_BREAK_ON_SEMICOLON
.It Dv FP_BREAK_ON_EQUALS
An equals sign
.Pq Ql Li =
is normally considered part of the directive.
This flag enables terminating the directive at the equals sign.
Also makes equals sign optional and transient.
.It Dv FP_BREAK_ON_SEMICOLON
A semicolon
.Pq Ql Li \;
is normally considered part of the value.
This flag enables terminating the value at the semicolon.
Also allows multiple statements on a single line separated by semicolon.
.It Dv FP_CASE_SENSITIVE
Normally directives are matched case insensitively using
.Xr fnmatch 3 .
This flag enables directive matching to be case sensitive.
.It Dv FP_REQUIRE_EQUALS
If a directive is not followed by an equals, processing is aborted.
.It Dv FP_STRICT_EQUALS
Equals must be part of the directive to be considered a delimiter between
directive and value.
.El
.Pp
The
.Fa options
struct array pointer can be NULL and every directive will invoke the
.Fn unknown
function argument.
.Pp
The directive for each fp_config item in the
.Fn parse_config
options argument is matched against each parsed directive using
.Xr fnmatch 3
until a match is found.
If a match is found, the
.Fn action
function for that fp_config directive is invoked with the line number,
directive, and value.
Otherwise if no match, the
.Fn unknown
function is invoked
.Pq with the same arguments .
.Pp
If either
.Fa action
or
.Fa unknown
return non-zero,
.Fn parse_config
aborts reading the file and returns the error value to its caller.
.Pp
.Fn get_config_option
traverses the options-array and returns the option that matches via
.Xr strcmp 3 ,
or if no match a pointer to a static dummy struct is returned
.Pq whose values are all zero or NULL .
.Pp
The use of
.Fa "struct fp_config"
is entirely optional as-is the use of
.Fa "enum fp_cfgtype"
or
.Fa "union fp_cfgvalue" .
For example, you could choose to pass a NULL pointer to
.Fn parse_config
for the first argument and then provide a simple
.Fa unknown
function based on
.Xr queue 3
that populates a singly-linked list of your own struct containing the
.Fa directive
and
.Fa value .
.Pp
In addition, the following miscellaneous string manipulation routines are
provided by
.In string_m.h :
.Bl -tag -width strexpandnl()
.It Fn replaceall
Replace all occurrences of
.Fa find
in
.Fa source
with
.Fa replace .
.It Fn strcount
Count the number of occurrences of one string that appear in the
.Fa source
string.
Return value is the total count.
An example use would be if you need to know how large a block of memory needs
to be for a
.Fn replaceall
series.
.It Fn strexpand
Expand escape sequences in a buffer pointed to by
.Fa source .
.It Fn strexpandnl
Expand only the escaped newlines in a buffer pointed to by
.Fa source .
.It Fn strtolower
Convert a string to lower case.
.El
.Sh SEE ALSO
.Xr queue 3
.Sh HISTORY
The
.Nm
library first appeared in
.Fx 11.0 .
.Sh AUTHORS
.An Devin Teske Aq dteske@FreeBSD.org
.Sh BUGS
This is the first implementation of the library,
and the interface may be subject to refinement.