path: root/WWW/Library/Implementation/HTFormat.h

/*
 * $LynxId: HTFormat.h,v 1.42 2022/04/01 07:54:14 tom Exp $
 *
 *                                            HTFormat: The format manager in the WWW Library
 *                          MANAGE DIFFERENT DOCUMENT FORMATS
 *
 * Here we describe the functions of the HTFormat module which handles conversion between
 * different data representations.  (In MIME parlance, a representation is known as a
 * content-type.  In WWW the term "format" is often used as it is shorter).
 *
 * This module is implemented by HTFormat.c.  This hypertext document is used to generate
 * the HTFormat.h include file.  Part of the WWW library.
 */
#ifndef HTFORMAT_H
#define HTFORMAT_H

#include <HTStream.h>
#include <HTAtom.h>
#include <HTList.h>
#include <HTAnchor.h>

#ifdef USE_SOURCE_CACHE
#include <HTChunk.h>
#endif

#ifdef USE_BZLIB
#include <bzlib.h>
#endif

#ifdef USE_ZLIB
#include <zlib.h>
#endif

#ifdef __cplusplus
extern "C" {
#endif
/*

   These macros (which used to be constants) define some basic internally
   referenced representations.  The www/xxx ones are of course not MIME
   standard.

   www/source is an output format which leaves the input untouched.  It is
   useful for diagnostics, and for users who want to see the original, whatever
   it is.

																	 */
/* Internal ones */
#define STR_SOURCE 	"www/source"
    extern HTAtom *WWW_SOURCE;	/* calculated once, heavy used */

/*

   www/present represents the user's perception of the document.  If you
   convert to www/present, you present the material to the user.

 */
#define STR_PRESENT	"www/present"
#define WWW_PRESENT	HTAtom_for(STR_PRESENT)		/* The user's perception */

#define WWW_DEBUG       HTAtom_for("www/debug")
/*

   WWW_DEBUG represents the user's perception of debug information, for example
   sent as a HTML document in a HTTP redirection message.

 */

/*

   The message/rfc822 format means a MIME message or a plain text message with
   no MIME header.  This is what is returned by an HTTP server.

 */
#define WWW_MIME HTAtom_for("www/mime")		/* A MIME message */

/*
  For parsing only the header. - kw
  */
#define WWW_MIME_HEAD   HTAtom_for("message/x-rfc822-head")

/*

   www/print is like www/present except it represents a printed copy.

 */
#define WWW_PRINT HTAtom_for("www/print")	/* A printed copy */

/*

   www/unknown is a really unknown type.  Some default action is appropriate.

 */
#define WWW_UNKNOWN     HTAtom_for("www/unknown")

#ifdef DIRED_SUPPORT
/*
   www/dired signals directory edit mode.
*/
#define WWW_DIRED      HTAtom_for("www/dired")
#endif

/*
 * Miscellaneous internal MIME types.
 */
#define STR_DOWNLOAD    "www/download"
#define WWW_DOWNLOAD    HTAtom_for(STR_DOWNLOAD)

#define STR_DUMP        "www/dump"
#define WWW_DUMP        HTAtom_for(STR_DUMP)

/*

   These are regular MIME types.  HTML is assumed to be added by the W3 code. 
   application/octet-stream was mistakenly application/binary in earlier libwww
   versions (pre 2.11).

 */
#define STR_BINARY      "application/octet-stream"
#define STR_PLAINTEXT   "text/plain"
#define STR_HTML        "text/html"

#define WWW_BINARY      HTAtom_for(STR_BINARY)
#define WWW_PLAINTEXT   HTAtom_for(STR_PLAINTEXT)
#define WWW_HTML        HTAtom_for(STR_HTML)

#define WWW_POSTSCRIPT  HTAtom_for("application/postscript")
#define WWW_RICHTEXT    HTAtom_for("application/rtf")
#define WWW_AUDIO       HTAtom_for("audio/basic")

    typedef HTAtom *HTEncoding;

/*
 * The following are values for the MIME types:
 */
#define WWW_ENC_7BIT            HTAtom_for("7bit")
#define WWW_ENC_8BIT            HTAtom_for("8bit")
#define WWW_ENC_BINARY          HTAtom_for("binary")

/*
 * We also add
 */
#define WWW_ENC_COMPRESS        HTAtom_for("compress")

/*
 * Does a string designate a real encoding, or is it just
 * a "dummy" as for example 7bit, 8bit, and binary?
 */
#define IsUnityEncStr(senc) \
        ((senc)==NULL || *(senc)=='\0' || !strcmp(senc,"identity") ||\
        !strcmp(senc,"8bit") || !strcmp(senc,"binary") || !strcmp(senc,"7bit"))

#define IsUnityEnc(enc) \
        ((enc)==NULL || (enc)==HTAtom_for("identity") ||\
        (enc)==WWW_ENC_8BIT || (enc)==WWW_ENC_BINARY || (enc)==WWW_ENC_7BIT)

/*

The HTPresentation and HTConverter types

   This HTPresentation structure represents a possible conversion algorithm
   from one format to another.  It includes a pointer to a conversion routine. 
   The conversion routine returns a stream to which data should be fed.  See
   also HTStreamStack which scans the list of registered converters and calls
   one.  See the initialisation module for a list of conversion routines.

 */
    typedef struct _HTPresentation HTPresentation;

    typedef HTStream *HTConverter (HTPresentation *pres,
				   HTParentAnchor *anchor,
				   HTStream *sink);

    struct _HTPresentation {
	HTAtom *rep;		/* representation name atomized */
	HTAtom *rep_out;	/* resulting representation */
	HTConverter *converter;	/* routine to gen the stream stack */
	char *command;		/* MIME-format command string */
	char *testcommand;	/* MIME-format test string */
	float quality;		/* Between 0 (bad) and 1 (good) */
	float secs;
	float secs_per_byte;
	off_t maxbytes;
	BOOL get_accept;	/* list in "Accept:" for GET */
	int accept_opt;		/* matches against LYAcceptMedia */
    };

/*

   The list of presentations is kept by this module.  It is also scanned by
   modules which want to know the set of formats supported.  for example.

 */
    extern HTList *HTPresentations;

/*

   The default presentation is used when no other is appropriate

 */
    extern HTPresentation *default_presentation;

/*
 * Options used for "Content-Type" string
 */
    typedef enum {
	contentBINARY = 0
	,contentTEXT
	,contentHTML
    } ContentType;

/*
 * Options used for "Accept:" string
 */
    typedef enum {
	/* make the components powers of two so we can add them */
	mediaINT = 1		/* internal types predefined in HTInit.c */
	,mediaEXT = 2		/* external types predefined in HTInit.c */
	,mediaCFG = 4		/* types, e.g., viewers, from lynx.cfg */
	,mediaUSR = 8		/* user's mime-types, etc. */
	,mediaSYS = 16		/* system's mime-types, etc. */
	/* these are useful flavors for the options menu */
	,mediaOpt1 = mediaINT
	,mediaOpt2 = mediaINT + mediaCFG
	,mediaOpt3 = mediaINT + mediaCFG + mediaUSR
	,mediaOpt4 = mediaINT + mediaCFG + mediaUSR + mediaSYS
	/* this is the flavor from pre-2.8.6 */
	,mediaALL = mediaINT + mediaEXT + mediaCFG + mediaUSR + mediaSYS
    } AcceptMedia;

/*
 * Options used for "Accept-Encoding:" string
 */
    typedef enum {
	encodingNONE = 0
	,encodingGZIP = 1
	,encodingDEFLATE = 2
	,encodingCOMPRESS = 4
	,encodingBZIP2 = 8
	,encodingBROTLI = 16
	,encodingALL = (encodingGZIP
			+ encodingDEFLATE
			+ encodingCOMPRESS
			+ encodingBZIP2
			+ encodingBROTLI)
    } AcceptEncoding;

/*

HTSetPresentation: Register a system command to present a format

  ON ENTRY,

  rep                     is the MIME - style format name

  command                 is the MAILCAP - style command template

  testcommand             is the MAILCAP - style testcommand template

  quality                 A degradation faction 0..1.0

  secs                    A limit on the time user will wait (0.0 for infinity)
  secs_per_byte

  maxbytes                A limit on the length acceptable as input (0 infinite)

  media                   Used in filtering presentation types for "Accept:"

 */
    extern void HTSetPresentation(const char *representation,
				  const char *command,
				  const char *testcommand,
				  double quality,
				  double secs,
				  double secs_per_byte,
				  long int maxbytes,
				  AcceptMedia media
    );

/*

HTSetConversion:   Register a conversion routine

  ON ENTRY,

  rep_in                  is the content-type input

  rep_out                 is the resulting content-type

  converter               is the routine to make the stream to do it

 */

    extern void HTSetConversion(const char *rep_in,
				const char *rep_out,
				HTConverter *converter,
				double quality,
				double secs,
				double secs_per_byte,
				long int maxbytes,
				AcceptMedia media
    );

/*

HTStreamStack:   Create a stack of streams

   This is the routine which actually sets up the conversion.  It currently
   checks only for direct conversions, but multi-stage conversions are forseen. 
   It takes a stream into which the output should be sent in the final format,
   builds the conversion stack, and returns a stream into which the data in the
   input format should be fed.  The anchor is passed because hypertxet objects
   load information into the anchor object which represents them.

 */
    extern HTStream *HTStreamStack(HTFormat format_in,
				   HTFormat format_out,
				   HTStream *stream_out,
				   HTParentAnchor *anchor);

/*
HTReorderPresentation: put presentation near head of list

    Look up a presentation (exact match only) and, if found, reorder it to the
    start of the HTPresentations list.  - kw
    */

    extern void HTReorderPresentation(HTFormat format_in,
				      HTFormat format_out);

/*
 * Setup 'get_accept' flag to denote presentations that are not redundant,
 * and will be listed in "Accept:" header.
 */
    extern void HTFilterPresentations(void);

/*

HTStackValue: Find the cost of a filter stack

   Must return the cost of the same stack which HTStreamStack would set up.

  ON ENTRY,

  format_in               The format of the data to be converted

  format_out              The format required

  initial_value           The intrinsic "value" of the data before conversion on a scale
                         from 0 to 1

  length                  The number of bytes expected in the input format

 */
    extern float HTStackValue(HTFormat format_in,
			      HTFormat rep_out,
			      double initial_value,
			      long int length);

#define NO_VALUE_FOUND  -1e20	/* returned if none found */

/*	Display the page while transfer in progress
 *	-------------------------------------------
 *
 *   Repaint the page only when necessary.
 *   This is a traverse call for HText_pageDispaly() - it works!.
 *
 */
    extern void HTDisplayPartial(void);

    extern void HTFinishDisplayPartial(void);

/*

HTCopy:  Copy a socket to a stream

   This is used by the protocol engines to send data down a stream, typically
   one which has been generated by HTStreamStack.

 */
    extern int HTCopy(HTParentAnchor *anchor,
		      int file_number,
		      void *handle,
		      HTStream *sink);

/*

HTFileCopy:  Copy a file to a stream

   This is used by the protocol engines to send data down a stream, typically
   one which has been generated by HTStreamStack.  It is currently called by
   HTParseFile

 */
    extern int HTFileCopy(FILE *fp,
			  HTStream *sink);

#ifdef USE_SOURCE_CACHE
/*

HTMemCopy:  Copy a memory chunk to a stream

   This is used by the protocol engines to send data down a stream, typically
   one which has been generated by HTStreamStack.  It is currently called by
   HTParseMem

 */
    extern int HTMemCopy(HTChunk *chunk,
			 HTStream *sink);
#endif

/*

HTCopyNoCR: Copy a socket to a stream, stripping CR characters.

   It is slower than HTCopy .

 */

    extern void HTCopyNoCR(HTParentAnchor *anchor,
			   int file_number,
			   HTStream *sink);

/*

Clear input buffer and set file number

   This routine and the one below provide simple character input from sockets. 
   (They are left over from the older architecture and may not be used very
   much.) The existence of a common routine and buffer saves memory space in
   small implementations.

 */
    extern void HTInitInput(int file_number);

/*

Get next character from buffer

 */
    extern int interrupted_in_htgetcharacter;
    extern int HTGetCharacter(void);

/*

HTParseSocket: Parse a socket given its format

   This routine is called by protocol modules to load an object.  uses
   HTStreamStack and the copy routines above.  Returns HT_LOADED if successful,
   <0 if not.

 */
    extern int HTParseSocket(HTFormat format_in,
			     HTFormat format_out,
			     HTParentAnchor *anchor,
			     int file_number,
			     HTStream *sink);

/*

HTParseFile: Parse a File through a file pointer

   This routine is called by protocols modules to load an object.  uses
   HTStreamStack and HTFileCopy.  Returns HT_LOADED if successful, can also
   return HT_PARTIAL_CONTENT, HT_NO_DATA, or other <0 for failure.

 */
    extern int HTParseFile(HTFormat format_in,
			   HTFormat format_out,
			   HTParentAnchor *anchor,
			   FILE *fp,
			   HTStream *sink);

#ifdef USE_SOURCE_CACHE
/*

HTParseMem: Parse a document in memory

   This routine is called by protocols modules to load an object.  uses
   HTStreamStack and HTMemCopy.  Returns HT_LOADED if successful, can also
   return <0 for failure.

 */
    extern int HTParseMem(HTFormat format_in,
			  HTFormat format_out,
			  HTParentAnchor *anchor,
			  HTChunk *chunk,
			  HTStream *sink);
#endif

#ifdef USE_ZLIB
/*
HTParseGzFile: Parse a gzip'ed File through a file pointer

   This routine is called by protocols modules to load an object.  uses
   HTStreamStack and HTGzFileCopy.  Returns HT_LOADED if successful, can also
   return HT_PARTIAL_CONTENT, HT_NO_DATA, or other <0 for failure.
 */
    extern int HTParseGzFile(HTFormat format_in,
			     HTFormat format_out,
			     HTParentAnchor *anchor,
			     gzFile gzfp,
			     HTStream *sink);

/*
HTParseZzFile: Parse a deflate'd File through a file pointer

   This routine is called by protocols modules to load an object.  uses
   HTStreamStack and HTZzFileCopy.  Returns HT_LOADED if successful, can also
   return HT_PARTIAL_CONTENT, HT_NO_DATA, or other <0 for failure.
 */
    extern int HTParseZzFile(HTFormat format_in,
			     HTFormat format_out,
			     HTParentAnchor *anchor,
			     FILE *zzfp,
			     HTStream *sink);

#endif				/* USE_ZLIB */

#ifdef USE_BZLIB
/*
HTParseBzFile: Parse a bzip2'ed File through a file pointer

   This routine is called by protocols modules to load an object.  uses
   HTStreamStack and HTBzFileCopy.  Returns HT_LOADED if successful, can also
   return HT_PARTIAL_CONTENT, HT_NO_DATA, or other <0 for failure.
 */
    extern int HTParseBzFile(HTFormat format_in,
			     HTFormat format_out,
			     HTParentAnchor *anchor,
			     BZFILE * bzfp,
			     HTStream *sink);

#endif				/* USE_BZLIB */

#ifdef USE_BROTLI
/*
HTParseBrFile: Parse a brotli'ed File through a file pointer

   This routine is called by protocols modules to load an object.  uses
   HTStreamStack and HTBrFileCopy.  Returns HT_LOADED if successful, can also
   return HT_PARTIAL_CONTENT, HT_NO_DATA, or other <0 for failure.
 */
    extern int HTParseBrFile(HTFormat format_in,
			     HTFormat format_out,
			     HTParentAnchor *anchor,
			     FILE *brfp,
			     HTStream *sink);

#endif				/* USE_BROTLI */

/*

HTNetToText: Convert Net ASCII to local representation

   This is a filter stream suitable for taking text from a socket and passing
   it into a stream which expects text in the local C representation.  It does
   ASCII and newline conversion.  As usual, pass its output stream to it when
   creating it.

 */
    extern HTStream *HTNetToText(HTStream *sink);

/*

HTFormatInit: Set up default presentations and conversions

   These are defined in HTInit.c or HTSInit.c if these have been replaced.  If
   you don't call this routine, and you don't define any presentations, then
   this routine will automatically be called the first time a conversion is
   needed.  However, if you explicitly add some conversions (eg using
   HTLoadRules) then you may want also to explicitly call this to get the
   defaults as well.

 */
    extern void HTFormatInit(void);

/*

Epilogue

 */
    extern BOOL HTOutputSource;	/* Flag: shortcut parser */

#ifdef __cplusplus
}
#endif
#endif				/* HTFORMAT_H */