/* -------------------------------------------------------------------------- **
 * Microsoft Network Services for Unix, AKA., Andrew Tridgell's SAMBA.
 *
 * This module Copyright (C) 1990-1998 Karl Auer
 *
 * Rewritten almost completely by Christopher R. Hertel, 1997.
 * This module Copyright (C) 1997-1998 by Christopher R. Hertel
 * 
 * -------------------------------------------------------------------------- **
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 *
 * -------------------------------------------------------------------------- **
 *
 * Module name: params
 *
 * -------------------------------------------------------------------------- **
 *
 *  This module performs lexical analysis and initial parsing of a
 *  Windows-like parameter file.  It recognizes and handles four token
 *  types:  section-name, parameter-name, parameter-value, and
 *  end-of-file.  Comments and line continuation are handled
 *  internally.
 *
 *  The entry point to the module is function pm_process().  This
 *  function opens the source file, calls the Parse() function to parse
 *  the input, and then closes the file when either the EOF is reached
 *  or a fatal error is encountered.
 *
 *  A sample parameter file might look like this:
 *
 *  [section one]
 *  parameter one = value string
 *  parameter two = another value
 *  [section two]
 *  new parameter = some value or t'other
 *
 *  The parameter file is divided into sections by section headers:
 *  section names enclosed in square brackets (eg. [section one]).
 *  Each section contains parameter lines, each of which consist of a
 *  parameter name and value delimited by an equal sign.  Roughly, the
 *  syntax is:
 *
 *    <file>            :==  { <section> } EOF
 *
 *    <section>         :==  <section header> { <parameter line> }
 *
 *    <section header>  :==  '[' NAME ']'
 *
 *    <parameter line>  :==  NAME '=' VALUE '\n'
 *
 *  Blank lines and comment lines are ignored.  Comment lines are lines
 *  beginning with either a semicolon (';') or a pound sign ('#').
 *
 *  All whitespace in section names and parameter names is compressed
 *  to single spaces.  Leading and trailing whitespace is stipped from
 *  both names and values.
 *
 *  Only the first equals sign in a parameter line is significant.
 *  Parameter values may contain equals signs, square brackets and
 *  semicolons.  Internal whitespace is retained in parameter values,
 *  with the exception of the '\r' character, which is stripped for
 *  historic reasons.  Parameter names may not start with a left square
 *  bracket, an equal sign, a pound sign, or a semicolon, because these
 *  are used to identify other tokens.
 *
 * -------------------------------------------------------------------------- **
 */

#include "includes.h"

/* -------------------------------------------------------------------------- **
 * Constants...
 */

#define BUFR_INC 1024


/* -------------------------------------------------------------------------- **
 * Variables...
 *
 *  DEBUGLEVEL  - The ubiquitous DEBUGLEVEL.  This determines which DEBUG()
 *                messages will be produced.
 *  bufr        - pointer to a global buffer.  This is probably a kludge,
 *                but it was the nicest kludge I could think of (for now).
 *  bSize       - The size of the global buffer <bufr>.
 */

/* we can't use FILE* due to the 256 fd limit - use this cheap hack
   instead */
typedef struct {
	char *buf;
	char *p;
	size_t size;
	char *end_section_p;
} myFILE;

static int mygetc(myFILE *f)
{
	if (f->p >= f->buf+f->size)
		return EOF;
        /* be sure to return chars >127 as positive values */
	return (int)( *(f->p++) & 0x00FF );
}

static void myfile_close(myFILE *f)
{
	if (!f)
		return;
	SAFE_FREE(f->buf);
	SAFE_FREE(f);
}

/* Find the end of the section. We must use mb functions for this. */
static int FindSectionEnd(myFILE *f)
{
	f->end_section_p = strchr_m(f->p, ']');
	return f->end_section_p ? 1 : 0;
}

static int AtSectionEnd(myFILE *f)
{
	if (f->p == f->end_section_p + 1) {
		f->end_section_p = NULL;
		return 1;
	}
	return 0;
}

/* -------------------------------------------------------------------------- **
 * Functions...
 */
  /* ------------------------------------------------------------------------ **
   * Scan past whitespace (see ctype(3C)) and return the first non-whitespace
   * character, or newline, or EOF.
   *
   *  Input:  InFile  - Input source.
   *
   *  Output: The next non-whitespace character in the input stream.
   *
   *  Notes:  Because the config files use a line-oriented grammar, we
   *          explicitly exclude the newline character from the list of
   *          whitespace characters.
   *        - Note that both EOF (-1) and the nul character ('\0') are
   *          considered end-of-file markers.
   *
   * ------------------------------------------------------------------------ **
   */
 
static int EatWhitespace( myFILE *InFile )
{
	int c;

	for( c = mygetc( InFile ); isspace( c ) && ('\n' != c); c = mygetc( InFile ) )
		;
	return( c );
}

  /* ------------------------------------------------------------------------ **
   * Scan to the end of a comment.
   *
   *  Input:  InFile  - Input source.
   *
   *  Output: The character that marks the end of the comment.  Normally,
   *          this will be a newline, but it *might* be an EOF.
   *
   *  Notes:  Because the config files use a line-oriented grammar, we
   *          explicitly exclude the newline character from the list of
   *          whitespace characters.
   *        - Note that both EOF (-1) and the nul character ('\0') are
   *          considered end-of-file markers.
   *
   * ------------------------------------------------------------------------ **
   */

static int EatComment( myFILE *InFile )
{
	int c;

	for( c = mygetc( InFile ); ('\n'!=c) && (EOF!=c) && (c>0); c = mygetc( InFile ) )
		;
	return( c );
}

/*****************************************************************************
 * Scan backards within a string to discover if the last non-whitespace
 * character is a line-continuation character ('\\').
 *
 *  Input:  line  - A pointer to a buffer containing the string to be
 *                  scanned.
 *          pos   - This is taken to be the offset of the end of the
 *                  string.  This position is *not* scanned.
 *
 *  Output: The offset of the '\\' character if it was found, or -1 to
 *          indicate that it was not.
 *
 *****************************************************************************/

static int Continuation(uint8_t *line, int pos )
{
	pos--;
	while( (pos >= 0) && isspace((int)line[pos]))
		pos--;

	return (((pos >= 0) && ('\\' == line[pos])) ? pos : -1 );
}

/* ------------------------------------------------------------------------ **
 * Scan a section name, and pass the name to function sfunc().
 *
 *  Input:  InFile  - Input source.
 *          sfunc   - Pointer to the function to be called if the section
 *                    name is successfully read.
 *
 *  Output: True if the section name was read and True was returned from
 *          <sfunc>.  False if <sfunc> failed or if a lexical error was
 *          encountered.
 *
 * ------------------------------------------------------------------------ **
 */

static bool Section( DATA_BLOB *buf, myFILE *InFile, bool (*sfunc)(const char *, void *), void *userdata )
{
	int   c;
	int   i;
	int   end;
	const char *func  = "params.c:Section() -";

	i = 0;      /* <i> is the offset of the next free byte in bufr[] and  */
	end = 0;    /* <end> is the current "end of string" offset.  In most  */
		    /* cases these will be the same, but if the last          */
		    /* character written to bufr[] is a space, then <end>     */
		    /* will be one less than <i>.                             */


	/* Find the end of the section. We must use mb functions for this. */
	if (!FindSectionEnd(InFile)) {
		DEBUG(0, ("%s No terminating ']' character in section.\n", func) );
		return False;
	}

	c = EatWhitespace( InFile );    /* We've already got the '['.  Scan */
					/* past initial white space.        */

	while( (EOF != c) && (c > 0) ) {
		/* Check that the buffer is big enough for the next character. */
		if( i > (buf->length - 2) ) {
			uint8_t *tb = (uint8_t *)SMB_REALLOC_KEEP_OLD_ON_ERROR(buf->data, buf->length+BUFR_INC );
			if(!tb) {
				DEBUG(0, ("%s Memory re-allocation failure.", func) );
				return False;
			}
			buf->data = tb;
			buf->length += BUFR_INC;
		}

		/* Handle a single character other than section end. */
		switch( c ) {
			case '\n': /* Got newline before closing ']'.    */
				i = Continuation( buf->data, i );    /* Check for line continuation.     */
				if( i < 0 ) {
					buf->data[end] = '\0';
					DEBUG(0, ("%s Badly formed line in configuration file: %s\n", func, buf->data ));
					return False;
				}
				end = ( (i > 0) && (' ' == buf->data[i - 1]) ) ? (i - 1) : (i);
					c = mygetc( InFile );             /* Continue with next line.         */
				break;

			default: /* All else are a valid name chars.   */
				if(isspace( c )) {
					/* One space per whitespace region. */
					buf->data[end] = ' ';
					i = end + 1;
					c = EatWhitespace( InFile );
				} else {
					buf->data[i++] = c;
					end = i;
					c = mygetc( InFile );
				}
		}

		if (AtSectionEnd(InFile)) {
			/* Got to the closing bracket. */
			buf->data[end] = '\0';
			if( 0 == end ) {
				/* Don't allow an empty name.       */
				DEBUG(0, ("%s Empty section name in configuration file.\n", func ));
				return False;
			}
			if( !sfunc((char *)buf->data, userdata) )            /* Got a valid name.  Deal with it. */
				return False;
			EatComment( InFile );     /* Finish off the line.             */
			return True;
		}

	}

	/* We arrive here if we've met the EOF before the closing bracket. */
	DEBUG(0, ("%s Unexpected EOF in the configuration file: %s\n", func, buf->data ));
	return False;
}

/* ------------------------------------------------------------------------ **
 * Scan a parameter name and value, and pass these two fields to pfunc().
 *
 *  Input:  InFile  - The input source.
 *          pfunc   - A pointer to the function that will be called to
 *                    process the parameter, once it has been scanned.
 *          c       - The first character of the parameter name, which
 *                    would have been read by Parse().  Unlike a comment
 *                    line or a section header, there is no lead-in
 *                    character that can be discarded.
 *
 *  Output: True if the parameter name and value were scanned and processed
 *          successfully, else False.
 *
 *  Notes:  This function is in two parts.  The first loop scans the
 *          parameter name.  Internal whitespace is compressed, and an
 *          equal sign (=) terminates the token.  Leading and trailing
 *          whitespace is discarded.  The second loop scans the parameter
 *          value.  When both have been successfully identified, they are
 *          passed to pfunc() for processing.
 *
 * ------------------------------------------------------------------------ **
 */

static bool Parameter( DATA_BLOB *buf, myFILE *InFile, bool (*pfunc)(const char *, const char *, void *), int c, void *userdata )
{
	int   i       = 0;    /* Position within bufr. */
	int   end     = 0;    /* bufr[end] is current end-of-string. */
	int   vstart  = 0;    /* Starting position of the parameter value. */
	const char *func    = "params.c:Parameter() -";

	/* Read the parameter name. */
	while( 0 == vstart ) {
		/* Loop until we've found the start of the value. */
		if( i > (buf->length - 2) ) {
			/* Ensure there's space for next char.    */
			uint8_t *tb = (uint8_t *)SMB_REALLOC_KEEP_OLD_ON_ERROR( buf->data, buf->length + BUFR_INC );
			if (!tb) {
				DEBUG(0, ("%s Memory re-allocation failure.", func) );
				return False;
			}
			buf->data = tb;
			buf->length += BUFR_INC;
		}

		switch(c) {
			case '=': /* Equal sign marks end of param name. */
				if( 0 == end ) {
					/* Don't allow an empty name.      */
					DEBUG(0, ("%s Invalid parameter name in config. file.\n", func ));
					return False;
				}
				buf->data[end++] = '\0';         /* Mark end of string & advance.   */
				i       = end;              /* New string starts here.         */
				vstart  = end;              /* New string is parameter value.  */
				buf->data[i] = '\0';             /* New string is nul, for now.     */
				break;

			case '\n': /* Find continuation char, else error. */
				i = Continuation( buf->data, i );
				if( i < 0 ) {
					buf->data[end] = '\0';
					DEBUG(1,("%s Ignoring badly formed line in configuration file: %s\n", func, buf->data ));
					return True;
				}
				end = ( (i > 0) && (' ' == buf->data[i - 1]) ) ? (i - 1) : (i);
				c = mygetc( InFile );       /* Read past eoln.                   */
				break;

			case '\0': /* Shouldn't have EOF within param name. */
			case EOF:
				buf->data[i] = '\0';
				DEBUG(1,("%s Unexpected end-of-file at: %s\n", func, buf->data ));
				return True;

			default:
				if(isspace( c )) {
					/* One ' ' per whitespace region.       */
					buf->data[end] = ' ';
					i = end + 1;
					c = EatWhitespace( InFile );
				} else {
					buf->data[i++] = c;
					end = i;
					c = mygetc( InFile );
				}
		}
	}

	/* Now parse the value. */
	c = EatWhitespace( InFile );  /* Again, trim leading whitespace. */
	while( (EOF !=c) && (c > 0) ) {
		if( i > (buf->length - 2) ) {
			/* Make sure there's enough room. */
			uint8_t *tb = (uint8_t *)SMB_REALLOC_KEEP_OLD_ON_ERROR( buf->data, buf->length + BUFR_INC );
			if (!tb) {
				DEBUG(0, ("%s Memory re-allocation failure.", func));
				return False;
			}
			buf->data = tb;
			buf->length += BUFR_INC;
		}

		switch(c) {
			case '\r': /* Explicitly remove '\r' because the older */
				c = mygetc( InFile );   /* version called fgets_slash() which also  */
				break;                /* removes them.                            */

			case '\n': /* Marks end of value unless there's a '\'. */
				i = Continuation( buf->data, i );
				if( i < 0 ) {
					c = 0;
				} else {
					for( end = i; (end >= 0) && isspace((int)buf->data[end]); end-- )
						;
					c = mygetc( InFile );
				}
				break;

			default: /* All others verbatim.  Note that spaces do not advance <end>.  This allows trimming  */
				buf->data[i++] = c;
				if( !isspace( c ) )  /* of whitespace at the end of the line.     */
					end = i;
				c = mygetc( InFile );
				break;
		}
	}
	buf->data[end] = '\0';          /* End of value. */

	return( pfunc( (char *)buf->data, (char *)&buf->data[vstart], userdata ) );   /* Pass name & value to pfunc().  */
}

/* ------------------------------------------------------------------------ **
 * Scan & parse the input.
 *
 *  Input:  InFile  - Input source.
 *          sfunc   - Function to be called when a section name is scanned.
 *                    See Section().
 *          pfunc   - Function to be called when a parameter is scanned.
 *                    See Parameter().
 *
 *  Output: True if the file was successfully scanned, else False.
 *
 *  Notes:  The input can be viewed in terms of 'lines'.  There are four
 *          types of lines:
 *            Blank      - May contain whitespace, otherwise empty.
 *            Comment    - First non-whitespace character is a ';' or '#'.
 *                         The remainder of the line is ignored.
 *            Section    - First non-whitespace character is a '['.
 *            Parameter  - The default case.
 * 
 * ------------------------------------------------------------------------ **
 */

static bool Parse( DATA_BLOB *buf, myFILE *InFile,
                   bool (*sfunc)(const char *, void *),
                   bool (*pfunc)(const char *, const char *, void *),
		   void *userdata)
{
	int    c;

	c = EatWhitespace( InFile );
	while( (EOF != c) && (c > 0) ) {
		switch( c ) {
			case '\n': /* Blank line. */
				c = EatWhitespace( InFile );
				break;

			case ';': /* Comment line. */
			case '#':
				c = EatComment( InFile );
				break;

			case '[': /* Section Header. */
				if( !Section( buf, InFile, sfunc, userdata ) )
					return False;
				c = EatWhitespace( InFile );
				break;

			case '\\': /* Bogus backslash. */
				c = EatWhitespace( InFile );
				break;

			default: /* Parameter line. */
				if( !Parameter( buf, InFile, pfunc, c, userdata ) )
					return False;
				c = EatWhitespace( InFile );
				break;
		}
	}
	return True;
}

/* ------------------------------------------------------------------------ **
 * Open a configuration file.
 *
 *  Input:  FileName  - The pathname of the config file to be opened.
 *
 *  Output: A pointer of type (char **) to the lines of the file
 *
 * ------------------------------------------------------------------------ **
 */

static myFILE *OpenConfFile( const char *FileName )
{
	const char *func = "params.c:OpenConfFile() -";
	int lvl = lp_is_in_client() ? 1 : 0;
	myFILE *ret;

	ret = SMB_MALLOC_P(myFILE);
	if (!ret)
		return NULL;

	ret->buf = file_load(FileName, &ret->size, 0);
	if( NULL == ret->buf ) {
		DEBUG( lvl, ("%s Unable to open configuration file \"%s\":\n\t%s\n",
			func, FileName, strerror(errno)) );
		SAFE_FREE(ret);
		return NULL;
	}

	ret->p = ret->buf;
	ret->end_section_p = NULL;
	return( ret );
}

/* ------------------------------------------------------------------------ **
 * Process the named parameter file.
 *
 *  Input:  FileName  - The pathname of the parameter file to be opened.
 *          sfunc     - A pointer to a function that will be called when
 *                      a section name is discovered.
 *          pfunc     - A pointer to a function that will be called when
 *                      a parameter name and value are discovered.
 *
 *  Output: TRUE if the file was successfully parsed, else FALSE.
 *
 * ------------------------------------------------------------------------ **
 */

bool pm_process( const char *FileName,
		bool (*sfunc)(const char *, void *),
		bool (*pfunc)(const char *, const char *, void *),
		void *userdata)
{
	int   result;
	myFILE *InFile;
	const char *func = "params.c:pm_process() -";
	DATA_BLOB buf;

	InFile = OpenConfFile( FileName );          /* Open the config file. */
	if( NULL == InFile )
		return False;

	DEBUG( 3, ("%s Processing configuration file \"%s\"\n", func, FileName) );

	buf = data_blob(NULL, 256);

	if (buf.data == NULL) {
		DEBUG(0,("%s memory allocation failure.\n", func));
		myfile_close(InFile);
		return False;
	}

	result = Parse( &buf, InFile, sfunc, pfunc, userdata );
	data_blob_free(&buf);

	myfile_close(InFile);

	if( !result ) {
		DEBUG(0,("%s Failed.  Error returned from params.c:parse().\n", func));
		return False;
	}

	return True;
}
