/*
** GIFtrans v1.11.1
**
** Convert any GIF file into a GIF89a
** Allows for setting the transparent or background color, changing colors,
** adding or removing comments. Also code to analyze GIF contents.
**
** Copyright (c) 24.2.94 by Andreas Ley <ley@rz.uni-karlsruhe.de>
**
** Permission to use, copy, modify, and distribute this software for any
** purpose and without fee is hereby granted, provided that the above
** copyright notice appears in all copies. This software is provided "as is"
** and without any express or implied warranties.
**
** This program has been tested on a HP9000/720 with HP-UX A.08.07
** In this environment, neither lint -u nor gcc -Wall produce any messages.
** If you encounter any errors or need to make any changes to port it
** to another platform, please contact me.
**
** Known bugs:
**	-B flag won't work if there's an Extension between the Global Color
**	Table and the Image Descriptor (or Graphic Control Extension). If -V
**	has been specified, a Warning Message will be displayed.
**	Will be fixed in 2.0
**	Always outputs GIF89a. Shouldn't do this if version is newer.
**	-D option may output changed data instead of original data, use
**	with caution, best only with then -L option.
**
** Version history
**
** Version 1.11.1 - 11.8.94
**	Allows for use of the -g option without the -B option.
**
** Version 1.11 - 21.7.94
**	Moved Plain Text Extension to the Extensions section where it belongs.
**	Accept Unknown Extension Labels.
**	Incorporated MS-DOS port by enzo@hk.net (Enzo Michelangeli).
**	Added -o and -e options to redirect stdout and stderr.
**	Added -D debug flag.
**
** Version 1.10.2 - 22.6.94
**	Support for -DRGBTXT flag.
**
** Version 1.10.1 - 21.6.94
**	Different rgb.txt file FreeBSD/386BSD.
**
** Version 1.10 - 19.6.94
**	Added -g option to change a color in the global color table.
**	Added -B option to change the color for the transparent color index.
**
** Version 1.9.1 - 7.6.94
**	Different rgb.txt files for X11 and Open Windows.
**
** Version 1.9 - 1.6.94
**	Fixed a bug which caused color names to be rejected.
**
** Version 1.8 - 30.5.94
**	Accept #rrggbb style arguments.
**	Do nothing if rgb-color not found in GIF.
**
** Version 1.7 - 16.5.94
**	Added -l option to only list the color table.
**	Added -L option for verbose output without creating a gif.
**	Added -b option to change the background color index.
**	Display all matching color names for color table entries.
**	Fixed a bug which caused bad color names if rgb.txt starts with
**		whitespace.
**	Doesn't use strdup anymore.
**	Fixed =& bug on dec machines.
**
** Version 1.6 - 5.4.94
**	Added color names recognition.
**
** Version 1.5 - 15.3.94
**	Added basic verbose output to analyze GIFs.
**
** Version 1.4 - 8.3.94
**	Fixed off-by-one bug in Local Color table code.
**	Added -c and -C options to add or remove a comment.
**	Transparency is no longer the default.
**
** Thanx for bug reports, ideas and fixes to
**	patricka@cs.kun.nl (Patrick Atoon)
**	wes@msc.edu (Wes Barris)
**	pmfitzge@ingr.com (Patrick M. Fitzgerald)
**	hoesel@chem.rug.nl (Frans van Hoesel)
**	boardman@jerry.sal.wisc.edu (Dan Boardman)
**	krweiss@chip.ucdavis.edu (Ken Weiss)
**	chuck.musciano@harris.com (Chuck Musciano)
**	heycke@camis.stanford.edu (Torsten Heycke)
**	claw@spacsun.rice.edu (Colin Law)
**	jwalker@eos.ncsu.edu (Joseph C. Walker)
**	Bjorn.Borud@alkymi.unit.no (Bjorn Borud)
**	Christopher.Vance@adfa.oz.au (CJS Vance)
**	pederl@norway.hp.com (Peder Langlo)
**	I.Rutson@bradford.ac.uk (Ian Rutson)
**	Nicolas.Pioch@enst.fr (Nicolas Pioch)
**	john@charles.CS.UNLV.EDU (John Kilburg)
**	enzo@hk.net (Enzo Michelangeli)
**	twv@hpwtwe0.cup.hp.com (Terry von Gease)
**
** Original distribution site is
**	ftp://ftp.rz.uni-karlsruhe.de/pub/net/www/tools/giftrans.c
** A man-page by knordlun@fltxa.helsinki.fi (Kai Nordlund) is at
**	ftp://ftp.rz.uni-karlsruhe.de/pub/net/www/tools/giftrans.1
** To compile for MS-DOS, you need getopt:
**	ftp://ftp.rz.uni-karlsruhe.de/pub/net/www/tools/getopt.c
** MS-DOS executable can be found at
**	ftp://ftp.rz.uni-karlsruhe.de/pub/net/www/tools/giftrans.exe
** A template rgb.txt for use with the MS-DOS version can be found at
**	ftp://ftp.rz.uni-karlsruhe.de/pub/net/www/tools/rgb.txt
** Additional info can be found on
**	http://melmac.corp.harris.com/transparent_images.html
*/

#define	X11		/* When using X Window System */
#undef	OPENWIN		/* When using Open Windows */
#undef	X386		/* When using FreeBSD/386BSD */
#undef	MSDOS		/* When using Borland C (maybe MSC too) */

char header[]="GIFtrans v1.11.1\n(c) 1994 by Andreas Ley\n";

#ifndef RGBTXT
#ifdef X11
#define	RGBTXT	"/usr/lib/X11/rgb.txt"
#else /* X11 */
#ifdef OPENWIN
#define	RGBTXT	"/usr/openwin/lib/rgb.txt"
#else /* OPENWIN */
#ifdef X386
#define	RGBTXT	"/usr/X386/lib/X11/rgb.txt"
#else /* X386 */
#ifdef MSDOS
#define	RGBTXT	"rgb.txt"
#else /* MSDOS */
#define	RGBTXT	"";
#endif /* MSDOS */
#endif /* X386 */
#endif /* OPENWIN */
#endif /* X11 */
#endif /* RGBTXT */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#ifndef MSDOS
#include <unistd.h>
#include <sys/param.h>
#else
#include <fcntl.h>
#include "getopt.c"
#endif

#ifndef MAXPATHLEN
#define MAXPATHLEN 256
#endif /* MAXPATHLEN */

#define	FALSE	(0)		/* This is the naked Truth */
#define	TRUE	(1)		/* and this is the Light */

#define	SUCCESS	(0)
#define	FAILURE	(1)

struct entry {
	struct entry	*next;
	char		*name;
	int		red;
	int		green;
	int		blue;
	} *root;

#define	NONE	(-1)
#define	OTHER	(-2)
#define	RGB	(-3)

struct color {
	int		index;
	int		red;
	int		green;
	int		blue;
	} bc,tc,tn,go,gn;

static char	*image,*comment;
static int	skipcomment,list,verbose,output,debug;
static long int	pos;

static char	rgb[] = RGBTXT;
static char	true[] = "True";
static char	false[] = "False";

#define	readword(buffer)	((buffer)[0]+256*(buffer)[1])
#define	readflag(buffer)	((buffer)?true:false)
#define	hex(c)			('a'<=(c)&&(c)<='z'?(c)-'a'+10:'A'<=(c)&&(c)<='Z'?(c)-'A'+10:(c)-'0')


void dump(adr,data,len)
long int	adr;
unsigned char	*data;
size_t		len;
{
	int	i;

	while (len>0) {
		(void)fprintf(stderr,"%08lx:%*s",adr,(int)((adr%16)*3+(adr%16>8?1:0)),"");
		for (i=adr%16;i<16&&len>0;i++,adr++,data++,len--)
			(void)fprintf(stderr,"%s%02x",i==8?"  ":" ",*data);
		(void)fprintf(stderr,"\n");
	}
}



void writedata(dest,data,len)
FILE		*dest;
unsigned char	*data;
size_t		len;
{
	unsigned char	size;

	while (len) {
		size=len<256?len:255;
		(void)fwrite((void *)&size,1,1,dest);
		(void)fwrite((void *)data,(size_t)size,1,dest);
		data+=size;
		len-=size;
	}
	size=0;
	(void)fwrite((void *)&size,1,1,dest);
}


void skipdata(src)
FILE	*src;
{
	unsigned char	size,buffer[256];

	do {
		pos=ftell(src);
		(void)fread((void *)&size,1,1,src);
		if (debug)
			dump(pos,&size,1);
		if (debug) {
			pos=ftell(src);
			(void)fread((void *)buffer,(size_t)size,1,src);
			dump(pos,buffer,(size_t)size);
		}
		else
			(void)fseek(src,(long int)size,SEEK_CUR);
	} while (!feof(src)&&size>0);
}


void transblock(src,dest)
FILE	*src;
FILE	*dest;
{
	unsigned char	size,buffer[256];

	pos=ftell(src);
	(void)fread((void *)&size,1,1,src);
	if (debug)
		dump(pos,&size,1);
	if (output)
		(void)fwrite((void *)&size,1,1,dest);
	pos=ftell(src);
	(void)fread((void *)buffer,(size_t)size,1,src);
	if (debug)
		dump(pos,buffer,(size_t)size);
	if (output)
		(void)fwrite((void *)buffer,(size_t)size,1,dest);
}


void transdata(src,dest)
FILE	*src;
FILE	*dest;
{
	unsigned char	size,buffer[256];

	do {
		pos=ftell(src);
		(void)fread((void *)&size,1,1,src);
		if (debug)
			dump(pos,&size,1);
		if (output)
			(void)fwrite((void *)&size,1,1,dest);
		pos=ftell(src);
		(void)fread((void *)buffer,(size_t)size,1,src);
		if (debug)
			dump(pos,buffer,(size_t)size);
		if (output)
			(void)fwrite((void *)buffer,(size_t)size,1,dest);
	} while (!feof(src)&&size>0);
}


int giftrans(src,dest)
FILE	*src;
FILE	*dest;
{
	unsigned char	buffer[3*256],lsd[7],gct[3*256],gce[5];
	unsigned int	cnt,cols,size,gct_size,gct_delay,gce_present;
	struct entry	*rgbptr;


	/* Header */
	pos=ftell(src);
	(void)fread((void *)buffer,6,1,src);
	if (strncmp((char *)buffer,"GIF",3)) {
		(void)fprintf(stderr,"No GIF file!\n");
		return(1);
	}
	if (verbose) {
		buffer[6]='\0';
		(void)fprintf(stderr,"Header: \"%s\"\n",buffer);
	}
	if (debug)
		dump(pos,buffer,6);
	if (output)
		(void)fputs("GIF89a",dest);

	/* Logical Screen Descriptor */
	pos=ftell(src);
	(void)fread((void *)lsd,7,1,src);
	if (verbose) {
		(void)fprintf(stderr,"Logical Screen Descriptor:\n");
		(void)fprintf(stderr,"\tLogical Screen Width: %d pixels\n",readword(lsd));
		(void)fprintf(stderr,"\tLogical Screen Height: %d pixels\n",readword(lsd+2));
		(void)fprintf(stderr,"\tGlobal Color Table Flag: %s\n",readflag(lsd[4]&0x80));
		(void)fprintf(stderr,"\tColor Resolution: %d bits\n",(lsd[4]&0x70>>4)+1);
		if (lsd[4]&0x80) {
			(void)fprintf(stderr,"\tSort Flag: %s\n",readflag(lsd[4]&0x8));
			(void)fprintf(stderr,"\tSize of Global Color Table: %d colors\n",2<<(lsd[4]&0x7));
			(void)fprintf(stderr,"\tBackground Color Index: %d\n",lsd[5]);
		}
		if (lsd[6])
			(void)fprintf(stderr,"\tPixel Aspect Ratio: %d (Aspect Ratio %f)\n",lsd[6],((double)lsd[6]+15)/64);
	}
	if (debug)
		dump(pos,lsd,7);

	/* Global Color Table */
	gct_delay=FALSE;
	if (lsd[4]&0x80) {
		gct_size=2<<(lsd[4]&0x7);
		pos=ftell(src);
		(void)fread((void *)gct,gct_size,3,src);
		if (go.index==RGB)
			for(cnt=0;cnt<gct_size&&go.index==RGB;cnt++)
				if (gct[3*cnt]==go.red&&gct[3*cnt+1]==go.green&&gct[3*cnt+2]==go.blue)
					go.index=cnt;
		if (go.index>=0) {
			if (gn.index>=0) {
				gn.red=gct[3*gn.index];
				gn.green=gct[3*gn.index+1];
				gn.blue=gct[3*gn.index+2];
			}
			gct[3*go.index]=gn.red;
			gct[3*go.index+1]=gn.green;
			gct[3*go.index+2]=gn.blue;
		}
		if (bc.index==RGB)
			for(cnt=0;cnt<gct_size&&bc.index==RGB;cnt++)
				if (gct[3*cnt]==bc.red&&gct[3*cnt+1]==bc.green&&gct[3*cnt+2]==bc.blue)
					bc.index=cnt;
		if (bc.index>=0)
			lsd[5]=bc.index;
		if (tc.index==RGB)
			for(cnt=0;cnt<gct_size&&tc.index==RGB;cnt++)
				if (gct[3*cnt]==tc.red&&gct[3*cnt+1]==tc.green&&gct[3*cnt+2]==tc.blue)
					tc.index=cnt;
		if (tc.index==OTHER)
			tc.index=lsd[5];
		if (tn.index>=0) {
			tn.red=gct[3*tn.index];
			tn.green=gct[3*tn.index+1];
			tn.blue=gct[3*tn.index+2];
		}
		if (tn.index!=NONE)
			gct_delay=TRUE;
	}
	if (output)
		(void)fwrite((void *)lsd,7,1,dest);
	if (lsd[4]&0x80) {
		if (list||verbose) {
			(void)fprintf(stderr,"Global Color Table:\n");
			for(cnt=0;cnt<gct_size;cnt++) {
				(void)fprintf(stderr,"\tColor %d: Red %d, Green %d, Blue %d",cnt,gct[3*cnt],gct[3*cnt+1],gct[3*cnt+2]);
				(void)fprintf(stderr,", #%02x%02x%02x",gct[3*cnt],gct[3*cnt+1],gct[3*cnt+2]);
				for (rgbptr=root,cols=0;rgbptr;rgbptr=rgbptr->next)
					if (rgbptr->red==gct[3*cnt]&&rgbptr->green==gct[3*cnt+1]&&rgbptr->blue==gct[3*cnt+2])
						(void)fprintf(stderr,"%s%s",cols++?", ":" (",rgbptr->name);
				(void)fprintf(stderr,"%s\n",cols?")":"");
			}
		}
		if (debug)
			dump(pos,gct,gct_size*3);
		if (output&&(!gct_delay))
			(void)fwrite((void *)gct,gct_size,3,dest);
	}

	gce_present=FALSE;
	do {
		pos=ftell(src);
		(void)fread((void *)buffer,1,1,src);
		switch (buffer[0]) {
		case 0x2c:	/* Image Descriptor */
			if (verbose)
				(void)fprintf(stderr,"Image Descriptor:\n");
			(void)fread((void *)(buffer+1),9,1,src);
			/* Write Graphic Control Extension */
			if (tc.index>=0||gce_present) {
				if (!gce_present) {
					gce[0]=0;
					gce[1]=0;
					gce[2]=0;
				}
				if (tc.index>=0) {
					gce[0]|=0x01;	/* Set Transparent Color Flag */
					gce[3]=tc.index;	/* Set Transparent Color Index */
				}
				else if (gce[0]&0x01)
					tc.index=gce[3];	/* Remember Transparent Color Index */
				gce[4]=0;
				if (tc.index>=0&&(!(buffer[8]&0x80))) { /* Transparent Color Flag set and no Local Color Table */
					gct[3*tc.index]=tn.red;
					gct[3*tc.index+1]=tn.green;
					gct[3*tc.index+2]=tn.blue;
				}
				if (output&&gct_delay) {
					(void)fwrite((void *)gct,gct_size,3,dest);
					gct_delay=FALSE;
				}
				if (output) {
					(void)fputs("\041\371\004",dest);