freebsd-nq/lib/libfigpar/figpar.3

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.Dd March 13, 2018
.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 figpar_config options[]"
.Fa "const char *path"
.Fa "int \*[lp]*unknown\*[rp]\*[lp]struct figpar_config *option"
.Fa "uint32_t line"
.Fa "char *directive"
.Fa "char *value\*[rp]"
.Fa "uint8_t processing_options"
.Fc
.Ft "struct figpar_config *"
.Fo get_config_option
.Fa "struct figpar_config options[]"
.Fa "const char *directive"
.Fc
.In string_m.h
.Ft int
.Fo replaceall
.Fa "char *source"
.Fa "const char *find"
.Fa "const char *replace"
.Fc
.Ft unsigned int
.Fo strcount
.Fa "const char *source"
.Fa "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 figpar_config {
    enum figpar_cfgtype		type;		/* value type */
    const char			*directive;	/* keyword */
    union figpar_cfgvalue	value;		/* value */

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

enum figpar_cfgtype {
    FIGPAR_TYPE_NONE      = 0x0000, /* directives with no value */
    FIGPAR_TYPE_BOOL      = 0x0001, /* boolean */
    FIGPAR_TYPE_INT       = 0x0002, /* signed 32 bit integer */
    FIGPAR_TYPE_UINT      = 0x0004, /* unsigned 32 bit integer */
    FIGPAR_TYPE_STR       = 0x0008, /* string pointer */
    FIGPAR_TYPE_STRARRAY  = 0x0010, /* string array pointer */
    FIGPAR_TYPE_DATA1     = 0x0020, /* void data type-1 (open) */
    FIGPAR_TYPE_DATA2     = 0x0040, /* void data type-2 (open) */
    FIGPAR_TYPE_DATA3     = 0x0080, /* void data type-3 (open) */
    FIGPAR_TYPE_RESERVED1 = 0x0100, /* reserved data type-1 */
    FIGPAR_TYPE_RESERVED2 = 0x0200, /* reserved data type-2 */
    FIGPAR_TYPE_RESERVED3 = 0x0400, /* reserved data type-3 */
};

union figpar_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:
.Bl -tag -width FIGPAR_BREAK_ON_SEMICOLON
.It Dv FIGPAR_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 FIGPAR_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 FIGPAR_CASE_SENSITIVE
Normally directives are matched case insensitively using
.Xr fnmatch 3 .
This flag enables directive matching to be case sensitive.
.It Dv FIGPAR_REQUIRE_EQUALS
If a directive is not followed by an equals,
processing is aborted.
.It Dv FIGPAR_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 run the
.Fn unknown
function argument.
.Pp
The directive for each figpar_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 figpar_config directive is run with the line number,
directive,
and value.
Otherwise if no match,
the
.Fn unknown
function is run
.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 figpar_config"
is entirely optional as-is the use of
.Fa "enum figpar_cfgtype"
or
.Fa "union figpar_cfgvalue" .
For example,
a NULL pointer can be passed to
.Fn parse_config
for the first argument while providing a simple
.Fa unknown
function based on
.Xr queue 3
that populates a singly-linked list of a struct containing the
.Fa directive
and
.Fa value .
.Pp
In addition,
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 to show 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 10.2 .
.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.