/************************************************************************
 *                                  *
 *          Copyright (c) 1982, Fred Fish           *
 *              All Rights Reserved             *
 *                                  *
 *  This software and/or documentation is released for public   *
 *  distribution for personal, non-commercial use only.     *
 *  Limited rights to use, modify, and redistribute are hereby  *
 *  granted for non-commercial purposes, provided that all      *
 *  copyright notices remain intact and all changes are clearly *
 *  documented.  The author makes no warranty of any kind with  *
 *  respect to this product and explicitly disclaims any implied    *
 *  warranties of merchantability or fitness for any particular *
 *  purpose.                            *
 *                                  *
 ************************************************************************
 */


/*
 *  LIBRARY FUNCTION
 *
 *  tgetstr   extract string capability from termcap entry
 *
 *  KEY WORDS
 *
 *  termcap
 *
 *  SYNOPSIS
 *
 *  char *tgetstr(id,area)
 *  char *id;
 *  char **area;
 *
 *  DESCRIPTION
 *
 *  Gets the string capability for <id>, placing it in
 *  the buffer at *area, and advancing *area to point
 *  to next available storage.
 *
 *  For example, if the following capabilities are
 *  in the termcap file:
 *
 *      ZZ=zzzz
 *      YY=yyyyyy
 *      WW=www
 *
 *  then successive calls using YY, ZZ, and WW will
 *  build the following buffer:
 *
 *      yyyyyy0zzzz0www0
 *
 *  The first call will return a pointer to yyyyyy, the
 *  second will return a pointer to zzzz and the third
 *  will return a pointer to www.  Note that each
 *  string is null terminated, as are all C strings.
 *
 *  Characters preceded by the carot character (\136)
 *  are mapped into the corresponding control character.
 *  For example, the two character sequence ^A becomes
 *  a single control-A (\001) character.
 *
 *  The escape character is the normal C backslash and
 *  the normal C escape sequences are recognized, along
 *  with a special sequence for the ASCII escape character
 *  (\033).  The recognized sequences are:
 *
 *      \E   =>  '\033'  (ASCII escape character)
 *      \b   =>  '\010'  (ASCII backspace character)
 *      \f   =>  '\014'  (ASCII form feed character)
 *      \n   =>  '\012'  (ASCII newline/linefeed char)
 *      \r   =>  '\015'  (ASCII carriage return char)
 *      \t   =>  '\011'  (ASCII tab character)
 *      \ddd =>  '\ddd'  (arbitrary ASCII digit)
 *      \x   =>  'x'     (ordinary ASCII character)
 *
 */

#include <stdio.h>
#include <ctype.h>
#ifdef VMS
# define index strchr
#endif
#ifdef ULTRIX
# include <strings.h>
#endif

extern char *_tcpbuf;       /* Termcap entry buffer pointer */

#ifdef MSDOS
    extern char *index();
#endif

/*
 *  PSEUDO CODE
 *
 *  Begin tgetstr
 *      Initialize pointer to the termcap entry buffer.
 *      While there is a field to process
 *      Skip over the field separator character.
 *      If this is the entry we want then
 *          If the entry is not a string then
 *          Return NULL.
 *          Else
 *          Transfer string and rtn pointer.
 *          End if
 *      End if
 *      End while
 *      Return NULL
 *  End tgetstr
 *
 */

char *tgetstr(id,area)
char *id;
char **area;
{
    char *bp;
    char *decode();

    bp = _tcpbuf;
    while ((bp = index(bp,':')) != NULL) {
    bp++;
    if (*bp++ == id[0] && *bp != NULL && *bp++ == id[1]) {
        if (*bp != NULL && *bp++ != '=') {
        return(NULL);
        } else {
        return(decode(bp,area));
        }
    }
    }
    return(NULL);
}

/*
 *  INTERNAL FUNCTION
 *
 *  decode   transfer string capability, decoding escapes
 *
 *  SYNOPSIS
 *
 *  static char *decode(bp,area)
 *  char *bp;
 *  char **area;
 *
 *  DESCRIPTION
 *
 *  Transfers the string capability, up to the next ':'
 *  character, or null, to the buffer pointed to by
 *  the pointer in *area.  Note that the initial
 *  value of *area and *area is updated to point
 *  to the next available location after the null
 *  terminating the transfered string.
 *
 *  BUGS
 *
 *  There is no overflow checking done on the destination
 *  buffer, so it better be large enough to hold
 *  all expected strings.
 *
 */

/*
 *  PSEUDO CODE
 *
 *  Begin decode
 *      Initialize the transfer pointer.
 *      While there is an input character left to process
 *      Switch on input character
 *      Case ESCAPE:
 *          Decode and xfer the escaped sequence.
 *          Break
 *      Case CONTROLIFY:
 *          Controlify and xfer the next character.
 *          Advance the buffer pointer.
 *          Break
 *      Default:
 *          Xfer a normal character.
 *      End switch
 *      End while
 *      Null terminate the output string.
 *      Remember where the output string starts.
 *      Update the output buffer pointer.
 *      Return pointer to the output string.
 *  End decode
 *
 */

static char *decode(bp,area)
char *bp;
char **area;
{
    char *cp, *bgn;
    char *do_esc();

    cp = *area;
    while (*bp != NULL && *bp != ':') {
    switch(*bp) {
    case '\\':
        bp = do_esc(cp++,++bp);
        break;
    case '^':
        *cp++ = *++bp & 037;
        bp++;
        break;
    default:
        *cp++ = *bp++;
        break;
    }
    }
    *cp++ = (char) NULL;
    bgn = *area;
    *area = cp;
    return(bgn);
}

/*
 *  INTERNAL FUNCTION
 *
 *  do_esc    process an escaped sequence
 *
 *  SYNOPSIS
 *
 *  char *do_esc(out,in);
 *  char *out;
 *  char *in;
 *
 *  DESCRIPTION
 *
 *  Processes an escape sequence pointed to by
 *  in, transfering it to location pointed to
 *  by out, and updating the pointer to in.
 *
 */

/*
 *  PSEUDO CODE
 *
 *  Begin do_esc
 *      If the first character is not a NULL then
 *      If is a digit then
 *          Set value to zero.
 *          For up to 3 digits
 *              Accumulate the sum.
 *          End for
 *          Transfer the sum.
 *          Else if character is in remap list then
 *          Transfer the remapped character.
 *          Advance the input pointer once.
 *          Else
 *          Simply transfer the character.
 *          End if
 *      End if
 *      Return updated input pointer.
 *  End do_esc
 *
 */

static char *maplist = {
    "E\033b\bf\fn\nr\rt\t"
};

char *do_esc(out,in)
char *out;
char *in;
{
    int count;
    char ch;
    char *cp;

    if (*in != NULL) {
    if (isdigit(*in)) {
        ch = 0;
        for (count = 0; count < 3 && isdigit(*in); in++) {
         ch <<= 3;
         ch |= (*in - '0');
        }
        *out++ = ch;
    } else if ((cp = index(maplist,*in)) != NULL) {
        *out++ = *++cp;
        in++;
    } else {
        *out++ = *in++;
    }
    }
    return(in);
}