.Dd Sep 9, 2015
.Dt LIBINIPARSER 3
.Os
.Sh NAME
.Nm libiniparser
.Nd simple parser for .ini files
.Sh SYNOPSIS
.In stdint.h
.In iniparser/iniparser.h
.Ft int
.Fo iniparser_init
.Fa void
.Fc
.Ft void
.Fo iniparser_destroy
.Fa void
.Fc
.Ft int
.Fo iniparser_open
.Fa "const char *path"
.Fa "iniparser_file_s **file"
.Fc
.Ft int
.Fo iniparser_close
.Fa "iniparser_file_s *file"
.Fc
.Ft int
.Fo iniparser_readline
.Fa "iniparser_file_s *file"
.Fa "inipaser_line_s *line"
.Fc
.Ft void
.Fo iniparser_line_init
.Fa "iniparser_line_s *line"
.Fc
.Ft void
.Fo iniparser_line_destroy
.Fa "iniparser_line_s *line"
.Fc
.Sh DESCRIPTION
.Nm
is a parsing library for .ini files. An ini file is of the form
.Bd -literal
[ section1 ]
keyA = valueA
keyB = valueB

[ section2 ]
keyA = valueA
keyB = valueB
keyC =
.Ed
.Ss OVERVIEW
The library is initialised with
.Nm iniparser_init ,
which will
.Sy must
be called before using the library. When no longer needed, the
.Nm libparser_destroy
function should be called to free resources.
Configuration files are represented by the
.Nm iniparser_file_s structure, which is defined as
.Bd -literal
typedef struct {
	FILE	*source;
	char	*lineptr;
	size_t	 linelen;
	ssize_t	 readlen;
} iniparser_file_s;
.Ed
.Pp
A configuration file may be opened with
.Nm iniparser_open ,
which if given a pointer to a NULL pointer to an
.Nm iniparser_file_s ,
will allocate space using
.Xr calloc 3 .
The caller must be sure then to free this memory when it is no longer
needed. Callers may also explicitly set the
.Ic source
pointer to the appropriate source file handle, and ensure that the
other fields are at zero values. Similarly,
.Nm iniparser_close
will close the source file handle and free any memory allocated inside
the structure. Users should still ensure that the structure itself is
freed as required.
.Nm iniparser_readline
will attempt to fill in the results of parsing the next line in the
configuration file. Note that it will keep reading lines, skipping
comments and blank lines, until it reads a valid section or key-value
line or until it encounters an error. The
.Nm iniparser_line_s
structure is defined as
.Bd -literal
typedef struct {
	uint8_t	 is_section;
	uint8_t	 is_set;
	char	*name;
	char	*value;
} iniparser_line_s;
.Ed
.Pp
A line should be initialised before first use with
.Nm iniparser_line_init ,
and should be destroyed after last use with
.Nm iniparser_line_destroy .
The fields are defined as:
.Bl -bullet -width Ds
.It
The is_section field will be set to 1 if the line was a new section.
.It
The is_set field will be set to 1 if valid data was set. This is
useful when an EOF is reached.
.It
The name field contains the section name if the is_section field is 1,
or the key if is_section is 0 and is_set is 1. It should be
disregarded outside of these two cases.
.It
The value field contains the key's value if is_section is 0 and is_set
is 1. It should be disregarded otherwise. If it is NULL, the key had
no value.
.El
Both the name and value field will have leading and trailing spaces
stripped. The line that is passed in is reset and its memory freed
every time
.Nm iniparser_readline
is run. Callers should copy any relevant data from the line elsewhere.
.Ss TYPICAL USAGE
Processing a file
generally follows the following steps:
.Bl -bullet
.It
Call
.Nm iniparser_open
with the path to the ini file and a pointer to an
.Nm iniparser_file_s
structure that will be used to manage the file parsing.
.It
Prepare the line storage variable with
.Nm iniparser_line_init .
.It
Call
.Nm iniparser_readline
to obtain successive values of the file.
.It
While iniparser_readline continues to succeed, keep processing the
results.
.It
Clean up with the following sequence:
.Bl -enum
.It
.Nm iniparser_line_destroy
.It
.Nm iniparser_close
.It
If the parser is no longer needed,
.Nm iniparser_destroy .
Once this is called, the library cannot be used until
.Nm iniparser_init
is called again.
.El
.El
.Ss THE REGULAR EXPRESSIONS
The following regular expressions are used:
.Bl -tag -width Ds
.It sections
"^\\[ *([a-zA-Z0-9_-]+) *\\]$"
.It blank lines
"^[ \t]*$"
.It comments
"^[ \t]*[#;]"
.It key-value lines
"^[ \t]*([a-zA-Z0-9_-]+)[ \t]*=(.*)$"
.El
.Sh RETURN VALUES
.Nm iniparser_init ,
.Nm iniparser_open ,
and
.Nm iniparser_readline
all return 0 on success and -1 on failure. Additionally,
.Nm iniparser_readline
uses 1 to signal EOF; the line value should be checked to determine if
there is new data and the file closed.
.Sh EXAMPLES
The following program will parse the files specified on the command
line and print sections and key/value pairs.
.Bd -literal
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

#include "iniparser/iniparser.h"


int
main(int argc, char *argv[])
{
	iniparser_file_s	*file = NULL;
	iniparser_line_s	 line;
	int			 i;
	int			 ret;

	ret = iniparser_init();
	if (0 != ret) {
		fprintf(stderr, "init failed: %d\n", ret);
		goto exit;
	}

	argc--;
	argv++;

	for (i = 0; i < argc; i++) {
		printf("Processing %s\n", argv[i]);
		ret = iniparser_open(argv[i], &file);
		if (0 != ret) {
			perror("_open");
			fprintf(stderr, "retval: %d\n", ret);
			goto exit;
		}
		iniparser_line_init(&line);

		while (1) {
			ret = iniparser_readline(file, &line);
			/* -1 is returned on error. */
			if (-1 == ret) {
				perror("_readline");
				fprintf(stderr, "retval: %d\n", ret);
				goto exit;
			}
			/* 1 means EOF. */
			else if (1 == ret) {
				ret = 0;
				break;
			}

			if (line.is_section) {
				printf("Now in section '%s'\n", line.name);
			}
			else {
				printf("Read key '%s' with value '%s'\n",
				    line.name, line.value);
			}

			iniparser_line_destroy(&line);		
		}

		iniparser_close(file);
		free(file);
		file = NULL;
		iniparser_line_destroy(&line);		
	}

exit:
	iniparser_line_destroy(&line);	
	if (argc > 0) {
		iniparser_destroy();
	}

	return ret==0;
}
.Ed
.Sh ERRORS
.Nm iniparser_open
will fail if its
.Ic file
argument is NULL, the call to
.Xr calloc 3
fails, or the source file could not be opened. Note that in the case
where memory is allocated by the library, it will be freed on exit.
.Pp
.Nm iniparser_close
returns the exit value of the call to
.Xr fclose 3 .
.Pp
.Nm iniparser_readline
will fail if there are any improperly formatted lines; comments and
blank lines will be skipped. It will also fail if it fails to read
a line from the file.
.Sh AUTHORS
.Nm
was written by
.An Kyle Isom Aq Mt kyle@tyrfingr.is .
.Sh LICENSE
.Nm
is released under the MIT license.