/* ansi2knr.c */
/* Convert ANSI C function definitions to K&R ("traditional C") syntax */

/*
ansi2knr is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY.  No author or distributor accepts responsibility to anyone for the
consequences of using it or for whether it serves any particular purpose or
works at all, unless he says so in writing.  Refer to the GNU General Public
License (the "GPL") for full details.

Everyone is granted permission to copy, modify and redistribute ansi2knr,
but only under the conditions described in the GPL.  A copy of this license
is supposed to have been given to you along with ansi2knr so you can know
your rights and responsibilities.  It should be in a file named COPYLEFT.
Among other things, the copyright notice and this notice must be preserved
on all copies.

We explicitly state here what we believe is already implied by the GPL: if
the ansi2knr program is distributed as a separate set of sources and a
separate executable file which are aggregated on a storage medium together
with another program, this in itself does not bring the other program under
the GPL, nor does the mere fact that such a program or the procedures for
constructing it invoke the ansi2knr executable bring any other part of the
program under the GPL.
*/

/*
 * Usage:
	ansi2knr input_file [output_file]
 * If no output_file is supplied, output goes to stdout.
 * There are no error messages.
 *
 * ansi2knr recognizes function definitions by seeing a non-keyword
 * identifier at the left margin, followed by a left parenthesis,
 * with a right parenthesis as the last character on the line,
 * and with a left brace as the first token on the following line
 * (ignoring possible intervening comments).
 * It will recognize a multi-line header provided that no intervening
 * line ends with a left or right brace or a semicolon.
 * These algorithms ignore whitespace and comments, except that
 * the function name must be the first thing on the line.
 * The following constructs will confuse it:
 *	- Any other construct that starts at the left margin and
 *	    follows the above syntax (such as a macro or function call).
 *	- Some macros that tinker with the syntax of the function header.
 */

/*
 * The original and principal author of ansi2knr is L. Peter Deutsch
 * <ghost@aladdin.com>.  Other authors are noted in the change history
 * that follows (in reverse chronological order):
	lpd 96-01-21 added code to cope with not HAVE_CONFIG_H and with
		compilers that don't understand void, as suggested by
		Tom Lane
	lpd 96-01-15 changed to require that the first non-comment token
		on the line following a function header be a left brace,
		to reduce sensitivity to macros, as suggested by Tom Lane
		<tgl@sss.pgh.pa.us>
	lpd 95-06-22 removed #ifndefs whose sole purpose was to define
		undefined preprocessor symbols as 0; changed all #ifdefs
		for configuration symbols to #ifs
	lpd 95-04-05 changed copyright notice to make it clear that
		including ansi2knr in a program does not bring the entire
		program under the GPL
	lpd 94-12-18 added conditionals for systems where ctype macros
		don't handle 8-bit characters properly, suggested by
		Francois Pinard <pinard@iro.umontreal.ca>;
		removed --varargs switch (this is now the default)
	lpd 94-10-10 removed CONFIG_BROKETS conditional
	lpd 94-07-16 added some conditionals to help GNU `configure',
		suggested by Francois Pinard <pinard@iro.umontreal.ca>;
		properly erase prototype args in function parameters,
		contributed by Jim Avera <jima@netcom.com>;
		correct error in writeblanks (it shouldn't erase EOLs)
	lpd 89-xx-xx original version
 */

/* Most of the conditionals here are to make ansi2knr work with */
/* or without the GNU configure machinery. */

#if HAVE_CONFIG_H
# include <config.h>
#endif

#include <stdio.h>
#include <ctype.h>

#if HAVE_CONFIG_H

/*
   For properly autoconfiguring ansi2knr, use AC_CONFIG_HEADER(config.h).
   This will define HAVE_CONFIG_H and so, activate the following lines.
 */

# if STDC_HEADERS || HAVE_STRING_H
#  include <string.h>
# else
#  include <strings.h>
# endif

#else /* not HAVE_CONFIG_H */

/* Otherwise do it the hard way */

# ifdef BSD
#  include <strings.h>
# else
#  ifdef VMS
    extern int strlen(), strncmp();
#  else
#   include <string.h>
#  endif
# endif

#endif /* not HAVE_CONFIG_H */

#if STDC_HEADERS
# include <stdlib.h>
#else
/*
   malloc and free should be declared in stdlib.h,
   but if you've got a K&R compiler, they probably aren't.
 */
# ifdef MSDOS
#  include <malloc.h>
# else
#  ifdef VMS
     extern char *malloc();
     extern void free();
#  else
     extern char *malloc();
     extern int free();
#  endif
# endif

#endif

/*
 * The ctype macros don't always handle 8-bit characters correctly.
 * Compensate for this here.
 */
#ifdef isascii
# undef HAVE_ISASCII		/* just in case */
# define HAVE_ISASCII 1
#else
#endif
#if STDC_HEADERS || !HAVE_ISASCII
# define is_ascii(c) 1
#else
# define is_ascii(c) isascii(c)
#endif

#define is_space(c) (is_ascii(c) && isspace(c))
#define is_alpha(c) (is_ascii(c) && isalpha(c))
#define is_alnum(c) (is_ascii(c) && isalnum(c))

/* Scanning macros */
#define isidchar(ch) (is_alnum(ch) || (ch) == '_')
#define isidfirstchar(ch) (is_alpha(ch) || (ch) == '_')

/* Forward references */
char *skipspace();
int writeblanks();
int test1();
int convert1();

/* The main program */
int
main(argc, argv)
    int argc;
    char *argv[];
{	FILE *in, *out;
#define bufsize 5000			/* arbitrary size */
	char *buf;
	char *line;
	char *more;
	/*
	 * In previous versions, ansi2knr recognized a --varargs switch.
	 * If this switch was supplied, ansi2knr would attempt to convert
	 * a ... argument to va_alist and va_dcl; if this switch was not
	 * supplied, ansi2knr would simply drop any such arguments.
	 * Now, ansi2knr always does this conversion, and we only
	 * check for this switch for backward compatibility.
	 */
	int convert_varargs = 1;

	if ( argc > 1 && argv[1][0] == '-' )
	  {	if ( !strcmp(argv[1], "--varargs") )
		  {	convert_varargs = 1;
			argc--;
			argv++;
		  }
		else
		  {	fprintf(stderr, "Unrecognized switch: %s\n", argv[1]);
			exit(1);
		  }
	  }
	switch ( argc )
	   {
	default:
		printf("Usage: ansi2knr input_file [output_file]\n");
		exit(0);
	case 2:
		out = stdout;
		break;
	case 3:
		out = fopen(argv[2], "w");
		if ( out == NULL )
		   {	fprintf(stderr, "Cannot open output file %s\n", argv[2]);
			exit(1);
		   }
	   }
	in = fopen(argv[1], "r");
	if ( in == NULL )
	   {	fprintf(stderr, "Cannot open input file %s\n", argv[1]);
		exit(1);
	   }
	fprintf(out, "#line 1 \"%s\"\n", argv[1]);
	buf = malloc(bufsize);
	line = buf;
	while ( fgets(line, (unsigned)(buf + bufsize - line), in) != NULL )
	   {
test:		line += strlen(line);
		switch ( test1(buf) )
		   {
		case 2:			/* a function header */
			convert1(buf, out, 1, convert_varargs);
			break;
		case 1:			/* a function */
			/* Check for a { at the start of the next line. */
			more = ++line;
f:			if ( line >= buf + (bufsize - 1) ) /* overflow check */
			  goto wl;
			if ( fgets(line, (unsigned)(buf + bufsize - line), in) == NULL )
			  goto wl;
			switch ( *skipspace(more, 1) )
			  {
			  case '{':
			    /* Definitely a function header. */
			    convert1(buf, out, 0, convert_varargs);
			    fputs(more, out);
			    break;
			  case 0:
			    /* The next line was blank or a comment: */
			    /* keep scanning for a non-comment. */
			    line += strlen(line);
			    goto f;
			  default:
			    /* buf isn't a function header, but */
			    /* more might be. */
			    fputs(buf, out);
			    strcpy(buf, more);
			    line = buf;
			    goto test;
			  }
			break;
		case -1:		/* maybe the start of a function */
			if ( line != buf + (bufsize - 1) ) /* overflow check */
			  continue;
			/* falls through */
		default:		/* not a function */
wl:			fputs(buf, out);
			break;
		   }
		line = buf;
	   }
	if ( line != buf )
	  fputs(buf, out);
	free(buf);
	fclose(out);
	fclose(in);
	return 0;
}

/* Skip over space and comments, in either direction. */
char *
skipspace(p, dir)
    register char *p;
    register int dir;			/* 1 for forward, -1 for backward */
{	for ( ; ; )
	   {	while ( is_space(*p) )
		  p += dir;
		if ( !(*p == '/' && p[dir] == '*') )
		  break;
		p += dir;  p += dir;
		while ( !(*p == '*' && p[dir] == '/') )
		   {	if ( *p == 0 )
			  return p;	/* multi-line comment?? */
			p += dir;
		   }
		p += dir;  p += dir;
	   }
	return p;
}

/*
 * Write blanks over part of a string.
 * Don't overwrite end-of-line characters.
 */
int
writeblanks(start, end)
    char *start;
    char *end;
{	char *p;
	for ( p = start; p < end; p++ )
	  if ( *p != '\r' && *p != '\n' )
	    *p = ' ';
	return 0;
}

/*
 * Test whether the string in buf is a function definition.
 * The string may contain and/or end with a newline.
 * Return as follows:
 *	0 - definitely not a function definition;
 *	1 - definitely a function definition;
 *	2 - definitely a function prototype (NOT USED);
 *	-1 - may be the beginning of a function definition,
 *		append another line and look again.
 * The reason we don't attempt to convert function prototypes is that
 * Ghostscript's declaration-generating macros look too much like
 * prototypes, and confuse the algorithms.
 */
int
test1(buf)
    char *buf;
{	register char *p = buf;
	char *bend;
	char *endfn;
	int contin;

	if ( !isidfirstchar(*p) )
	  return 0;		/* no name at left margin */
	bend = skipspace(buf + strlen(buf) - 1, -1);
	switch ( *bend )
	   {
	   case ';': contin = 0 /*2*/; break;
	   case ')': contin = 1; break;
	   case '{': return 0;		/* not a function */
	   case '}': return 0;		/* not a function */
	   default: contin = -1;
	   }
	while ( isidchar(*p) )
	  p++;
	endfn = p;
	p = skipspace(p, 1);
	if ( *p++ != '(' )
	  return 0;		/* not a function */
	p = skipspace(p, 1);
	if ( *p == ')' )
	  return 0;		/* no parameters */
	/* Check that the apparent function name isn't a keyword. */
	/* We only need to check for keywords that could be followed */
	/* by a left parenthesis (which, unfortunately, is most of them). */
	   {	static char *words[] =
		   {	"asm", "auto", "case", "char", "const", "double",
			"extern", "float", "for", "if", "int", "long",
			"register", "return", "short", "signed", "sizeof",
			"static", "switch", "typedef", "unsigned",
			"void", "volatile", "while", 0
		   };
		char **key = words;
		char *kp;
		int len = endfn - buf;

		while ( (kp = *key) != 0 )
		   {	if ( strlen(kp) == len && !strncmp(kp, buf, len) )
			  return 0;	/* name is a keyword */
			key++;
		   }
	   }
	return contin;
}

/* Convert a recognized function definition or header to K&R syntax. */
int
convert1(buf, out, header, convert_varargs)
    char *buf;
    FILE *out;
    int header;			/* Boolean */
    int convert_varargs;	/* Boolean */
{	char *endfn;
	register char *p;
	/*
	 * The breaks table contains pointers to the beginning and end
	 * of each argument.
	 */
	char **breaks;
	unsigned num_breaks = 2;	/* for testing */
	char **btop;
	char **bp;
	char **ap;
	char *vararg = 0;

	/* Pre-ANSI implementations don't agree on whether strchr */
	/* is called strchr or index, so we open-code it here. */
	for ( endfn = buf; *(endfn++) != '('; )
	  ;
top:	p = endfn;
	breaks = (char **)malloc(sizeof(char *) * num_breaks * 2);
	if ( breaks == 0 )
	   {	/* Couldn't allocate break table, give up */
		fprintf(stderr, "Unable to allocate break table!\n");
		fputs(buf, out);
		return -1;
	   }
	btop = breaks + num_breaks * 2 - 2;
	bp = breaks;
	/* Parse the argument list */
	do
	   {	int level = 0;
		char *lp = NULL;
		char *rp;
		char *end = NULL;

		if ( bp >= btop )
		   {	/* Filled up break table. */
			/* Allocate a bigger one and start over. */
			free((char *)breaks);
			num_breaks <<= 1;
			goto top;
		   }
		*bp++ = p;
		/* Find the end of the argument */
		for ( ; end == NULL; p++ )
		   {	switch(*p)
			   {
			   case ',':
				if ( !level ) end = p;
				break;
			   case '(':
				if ( !level ) lp = p;
				level++;
				break;
			   case ')':
				if ( --level < 0 ) end = p;
				else rp = p;
				break;
			   case '/':
				p = skipspace(p, 1) - 1;
				break;
			   default:
				;
			   }
		   }
		/* Erase any embedded prototype parameters. */
		if ( lp )
		  writeblanks(lp + 1, rp);
		p--;			/* back up over terminator */
		/* Find the name being declared. */
		/* This is complicated because of procedure and */
		/* array modifiers. */
		for ( ; ; )
		   {	p = skipspace(p - 1, -1);
			switch ( *p )
			   {
			   case ']':	/* skip array dimension(s) */
			   case ')':	/* skip procedure args OR name */
			   {	int level = 1;
				while ( level )
				 switch ( *--p )
				   {
				   case ']': case ')': level++; break;
				   case '[': case '(': level--; break;
				   case '/': p = skipspace(p, -1) + 1; break;
				   default: ;
				   }
			   }
				if ( *p == '(' && *skipspace(p + 1, 1) == '*' )
				   {	/* We found the name being declared */
					while ( !isidfirstchar(*p) )
					  p = skipspace(p, 1) + 1;
					goto found;
				   }
				break;
			   default:
				goto found;
			   }
		   }
found:		if ( *p == '.' && p[-1] == '.' && p[-2] == '.' )
		  {	if ( convert_varargs )
			  {	*bp++ = "va_alist";
				vararg = p-2;
			  }
			else
			  {	p++;
				if ( bp == breaks + 1 )	/* sole argument */
				  writeblanks(breaks[0], p);
				else
				  writeblanks(bp[-1] - 1, p);
				bp--;
			  }
		   }
		else
		   {	while ( isidchar(*p) ) p--;
			*bp++ = p+1;
		   }
		p = end;
	   }
	while ( *p++ == ',' );
	*bp = p;
	/* Make a special check for 'void' arglist */
	if ( bp == breaks+2 )
	   {	p = skipspace(breaks[0], 1);
		if ( !strncmp(p, "void", 4) )
		   {	p = skipspace(p+4, 1);
			if ( p == breaks[2] - 1 )
			   {	bp = breaks;	/* yup, pretend arglist is empty */
				writeblanks(breaks[0], p + 1);
			   }
		   }
	   }
	/* Put out the function name and left parenthesis. */
	p = buf;
	while ( p != endfn ) putc(*p, out), p++;
	/* Put out the declaration. */
	if ( header )
	  {	fputs(");", out);
		for ( p = breaks[0]; *p; p++ )
		  if ( *p == '\r' || *p == '\n' )
		    putc(*p, out);
	  }
	else
	  {	for ( ap = breaks+1; ap < bp; ap += 2 )
		  {	p = *ap;
			while ( isidchar(*p) )
			  putc(*p, out), p++;
			if ( ap < bp - 1 )
			  fputs(", ", out);
		  }
		fputs(")  ", out);
		/* Put out the argument declarations */
		for ( ap = breaks+2; ap <= bp; ap += 2 )
		  (*ap)[-1] = ';';
		if ( vararg != 0 )
		  {	*vararg = 0;
			fputs(breaks[0], out);		/* any prior args */
			fputs("va_dcl", out);		/* the final arg */
			fputs(bp[0], out);
		  }
		else
		  fputs(breaks[0], out);
	  }
	free((char *)breaks);
	return 0;
}