FIGPAR(3)

NAME
figpar, parse_config, get_config_option - configuration file parsing library

LIBRARY
libfigpar

SYNOPSIS
#include <figpar.h>
int
parse_config(struct fp_config options[], const char *path, int *unknownstruct fp_config *option, uint32_t line, char *directive, char *value, uint8_t processing_options);
struct fp_config *
get_config_option(struct fp_config options[], const char *directive);
#include <string_m.h>
int
replaceall(char *source, const char *find, const char *replace);
unsigned int
strcount(const char *source, const char *find);
void
strexpand(char *source);
void
strexpandnl(char *source);
void
strtolower(char *source);

DESCRIPTION
The figpar library provides a light-weight, portable framework for parsing configuration files. The library uses open(2), read(2), and lseek(2) within the file pointed to by path to find directives and values which are then made available to the application.

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.

Configuration directives, types, and callback functions are provided through data structures defined in <figpar.h>:

    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) */
    };

The processing_options argument to parse_config() is a mask of bit fields which indicate various processing options. The possible flags are as follows:

FP_BREAK_ON_EQUALS
    An equals sign (‘=’) is normally considered part of the directive. This flag enables terminating the directive at the equals sign. Also makes equals sign optional and transient.

FP_BREAK_ON_SEMICOLON
    A semicolon (‘’); 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.

FP_CASE_SENSITIVE
    Normally directives are matched case insensitively using fnmatch(3). This flag enables directive matching to be case sensitive.

FP_REQUIRE_EQUALS
    If a directive is not followed by an equals, processing is aborted.

FP_STRICT_EQUALS
    Equals must be part of the directive to be considered a delimiter between directive and value.

The options struct array pointer can be NULL and every directive will invoke the unknown() function argument.

The directive for each fp_config item in the parse_config() options argument is matched against each parsed directive using fnmatch(3) until a match is found. If a match is found, the action() function for that fp_config directive is invoked with the line number, directive, and value. Otherwise if no match, the unknown() function is invoked (with the same arguments).

If either action or unknown return non-zero, parse_config() aborts reading the file and returns the error value to its caller.

get_config_option() traverses the options-array and returns the option that matches via strcmp(3), or if no match a pointer to a static dummy struct is returned (whose values are all zero or NULL).

The use of struct fp_config is entirely optional as-is the use of enum fp_cfgtype or union fp_cfgvalue. For example, you could choose to pass a NULL pointer to parse_config() for the first argument and then provide a simple unknown function based on queue(3) that populates a singly-linked list of your own struct containing the directive and value.

In addition, the following miscellaneous string manipulation routines are provided by <string_m.h>:

replaceall()
    Replace all occurrences of find in source with replace.

strcount()
    Count the number of occurrences of one string that appear in the 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 replaceall() series.

strexpand()
    Expand escape sequences in a buffer pointed to by source.

strexpandnl()
    Expand only the escaped newlines in a buffer pointed to by source.

strtolower()
    Convert a string to lower case.

SEE ALSO
queue(3)

HISTORY
The figpar library first appeared in FreeBSD 11.0.

AUTHORS
Devin Teske <dteske@FreeBSD.org>

BUGS
This is the first implementation of the library, and the interface may be subject to refinement.