/********************************************
fin.c
copyright 1991, 1992.  Michael D. Brennan

This is a source file for mawk, an implementation of
the AWK programming language.

Mawk is distributed without warranty under the terms of
the GNU General Public License, version 2, 1991.
********************************************/

/*$Log: fin.c,v $
 * Revision 1.10  1995/12/24  22:23:22  mike
 * remove errmsg() from inside FINopen
 *
 * Revision 1.9  1995/06/06  00:18:29  mike
 * change mawk_exit(1) to mawk_exit(2)
 *
 * Revision 1.8  1994/12/13  00:26:35  mike
 * rt_nr and rt_fnr for run-time error messages
 *
 * Revision 1.7  1994/12/11  23:25:05  mike
 * -Wi option
 *
 * Revision 1.6  1994/12/11  22:14:15  mike
 * remove THINK_C #defines.  Not a political statement, just no indication
 * that anyone ever used it.
 *
 * Revision 1.5  1994/10/08  19:15:42  mike
 * remove SM_DOS
 *
 * Revision 1.4  1993/07/17  13:22:55  mike
 * indent and general code cleanup
 *
 * Revision 1.3  1993/07/15  13:26:55  mike
 * SIZE_T and indent
 *
 * Revision 1.2	 1993/07/04  12:51:57  mike
 * start on autoconfig changes
 *
 * Revision 1.1.1.1  1993/07/03	 18:58:13  mike
 * move source to cvs
 *
 * Revision 5.7	 1993/01/01  21:30:48  mike
 * split new_STRING() into new_STRING and new_STRING0
 *
 * Revision 5.6	 1992/12/17  02:48:01  mike
 * 1.1.2d changes for DOS
 *
 * Revision 5.5	 1992/07/28  15:11:30  brennan
 * minor change in finding eol, needed for MsDOS
 *
 * Revision 5.4	 1992/07/10  16:17:10  brennan
 * MsDOS: remove NO_BINMODE macro
 *
 * Revision 5.3	 1992/07/08  16:14:27  brennan
 * FILENAME and FNR retain last values in the
 * END block.
 *
 * Revision 5.2	 1992/02/21  13:30:08  brennan
 * fixed bug that free'd FILENAME twice if
 * command line was var=value only
 *
 * Revision 5.1	 91/12/05  07:56:02  brennan
 * 1.1 pre-release
 *
*/

/* fin.c */

#include "mawk.h"
#include "fin.h"
#include "memory.h"
#include "bi_vars.h"
#include "field.h"
#include "symtype.h"
#include "scan.h"

#ifndef	  NO_FCNTL_H
#include <fcntl.h>
#endif

/* This file handles input files.  Opening, closing,
   buffering and (most important) splitting files into
   records, FINgets().
*/

int PROTO(isatty, (int)) ;

static FIN *PROTO(next_main, (int)) ;
static char *PROTO(enlarge_fin_buffer, (FIN *)) ;
static void PROTO(set_main_to_stdin, (void)) ;
int PROTO(is_cmdline_assign, (char *)) ; /* also used by init */

/* convert file-descriptor to FIN*.
   It's the main stream if main_flag is set
*/
FIN *
FINdopen(fd, main_flag)
   int fd, main_flag ;
{
   register FIN *fin = ZMALLOC(FIN) ;

   fin->fd = fd ;
   fin->flags = main_flag ? (MAIN_FLAG | START_FLAG) : START_FLAG ;
   fin->buffp = fin->buff = (char *) zmalloc(BUFFSZ + 1) ;
   fin->nbuffs = 1 ;
   fin->buff[0] = 0 ;

   if ((isatty(fd) && rs_shadow.type == SEP_CHAR && rs_shadow.c == '\n')
       || (interactive_flag && fd == 0) )
   {
      /* interactive, i.e., line buffer this file */
      if (fd == 0)  fin->fp = stdin ;
      else if (!(fin->fp = fdopen(fd, "r")))
      {
	 errmsg(errno, "fdopen failed") ; mawk_exit(2) ; 
      }
   }
   else	 fin->fp = (FILE *) 0 ;

   return fin ;
}

/* open a FIN* by filename.
   It's the main stream if main_flag is set.
   Recognizes "-" as stdin.
*/

FIN *
FINopen(filename, main_flag)
   char *filename ;
   int main_flag ;
{
   int fd ;
   int oflag = O_RDONLY ;

#if  MSDOS
   int bm = binmode() & 1 ;
   if (bm)  oflag |= O_BINARY ;
#endif

   if (filename[0] == '-' && filename[1] == 0)
   {
#if  MSDOS
      if (bm)  setmode(0, O_BINARY) ;
#endif
      return FINdopen(0, main_flag) ;
   }

   if ((fd = open(filename, oflag, 0)) == -1)
      return (FIN *) 0 ;
   else 
      return FINdopen(fd, main_flag) ;
}

/* frees the buffer and fd, but leaves FIN structure until
   the user calls close() */

void
FINsemi_close(fin)
   register FIN *fin ;
{
   static char dead = 0 ;

   if (fin->buff != &dead)
   {
      zfree(fin->buff, fin->nbuffs * BUFFSZ + 1) ;

      if (fin->fd)
	{
	 if (fin->fp)  fclose(fin->fp) ;
	 else  close(fin->fd) ;
	}

      fin->buff = fin->buffp = &dead ;	 /* marks it semi_closed */
   }
   /* else was already semi_closed */
}

/* user called close() on input file */
void
FINclose(fin)
   FIN *fin ;
{
   FINsemi_close(fin) ;
   ZFREE(fin) ;
}

/* return one input record as determined by RS,
   from input file (FIN)  fin
*/

char *
FINgets(fin, len_p)
   FIN *fin ;
   unsigned *len_p ;
{
   register char *p, *q ;
   unsigned match_len ;
   unsigned r ;

restart :

   if (!(p = fin->buffp)[0])	/* need a refill */
   {
      if (fin->flags & EOF_FLAG)
      {
	 if (fin->flags & MAIN_FLAG)
	 {
	    fin = next_main(0) ;  goto restart ; 
	 }
	 else
	 {
	    *len_p = 0 ; return (char *) 0 ; 
	 }
      }

      if (fin->fp)
      {
	 /* line buffering */
	 if (!fgets(fin->buff, BUFFSZ + 1, fin->fp))
	 {
	    fin->flags |= EOF_FLAG ;
	    fin->buff[0] = 0 ;
	    fin->buffp = fin->buff ;
	    goto restart ;	 /* might be main_fin */
	 }
	 else  /* return this line */
	 {
	    /* find eol */
	    p = fin->buff ;
	    while (*p != '\n' && *p != 0)  p++ ;

	    *p = 0 ; *len_p = p - fin->buff ;
	    fin->buffp = p ;
	    return fin->buff ;
	 }
      }
      else
      {
	 /* block buffering */
	 r = fillbuff(fin->fd, fin->buff, fin->nbuffs * BUFFSZ) ;
	 if (r == 0)
	 {
	    fin->flags |= EOF_FLAG ;
	    fin->buffp = fin->buff ;
	    goto restart ;	 /* might be main */
	 }
	 else if (r < fin->nbuffs * BUFFSZ)
	 {
	    fin->flags |= EOF_FLAG ;
	 }

	 p = fin->buffp = fin->buff ;

	 if (fin->flags & START_FLAG)
	 {
	    fin->flags &= ~START_FLAG ;
	    if (rs_shadow.type == SEP_MLR)
	    {
	       /* trim blank lines from front of file */
	       while (*p == '\n')  p++ ;
	       fin->buffp = p ;
	       if (*p == 0)  goto restart ;
	    }
	 }
      }
   }

retry:

   switch (rs_shadow.type)
   {
      case SEP_CHAR:
	 q = strchr(p, rs_shadow.c) ;
	 match_len = 1 ;
	 break ;

      case SEP_STR:
	 q = str_str(p, ((STRING *) rs_shadow.ptr)->str,
		     match_len = ((STRING *) rs_shadow.ptr)->len) ;
	 break ;

      case SEP_MLR:
      case SEP_RE:
	 q = re_pos_match(p, rs_shadow.ptr, &match_len) ;
	 /* if the match is at the end, there might still be
	       more to match in the file */
	 if (q && q[match_len] == 0 && !(fin->flags & EOF_FLAG))
	    q = (char *) 0 ;
	 break ;

      default:
	 bozo("type of rs_shadow") ;
   }

   if (q)
   {
      /* the easy and normal case */
      *q = 0 ;	*len_p = q - p ;
      fin->buffp = q + match_len ;
      return p ;
   }

   if (fin->flags & EOF_FLAG)
   {
      /* last line without a record terminator */
      *len_p = r = strlen(p) ; fin->buffp = p+r ;

      if (rs_shadow.type == SEP_MLR && fin->buffp[-1] == '\n'
	  && r != 0)
      {
	 (*len_p)-- ;
	 *--fin->buffp = 0 ;
      }
      return p ;
   }

   if (p == fin->buff)
   {
      /* current record is too big for the input buffer, grow buffer */
      p = enlarge_fin_buffer(fin) ;
   }
   else
   {
      /* move a partial line to front of buffer and try again */
      unsigned rr ;

      p = (char *) memcpy(fin->buff, p, r = strlen(p)) ;
      q = p+r ;	 rr = fin->nbuffs*BUFFSZ - r ;

      if ((r = fillbuff(fin->fd, q, rr)) < rr)
	 fin->flags |= EOF_FLAG ;
   }
   goto retry ;
}

static char *
enlarge_fin_buffer(fin)
   FIN *fin ;
{
   unsigned r ;
   unsigned oldsize = fin->nbuffs * BUFFSZ + 1 ;

#ifdef  MSDOS
   /* I'm not sure this can really happen:
     avoid "16bit wrap" */
   if (fin->nbuffs == MAX_BUFFS)
   {
      errmsg(0, "out of input buffer space") ;
      mawk_exit(2) ;
   }
#endif

   fin->buffp =
      fin->buff = (char *) zrealloc(fin->buff, oldsize, oldsize + BUFFSZ) ;
   fin->nbuffs++ ;

   r = fillbuff(fin->fd, fin->buff + (oldsize - 1), BUFFSZ) ;
   if (r < BUFFSZ)  fin->flags |= EOF_FLAG ;

   return fin->buff ;
}

/*--------
  target is big enough to hold size + 1 chars
  on exit the back of the target is zero terminated
 *--------------*/
unsigned
fillbuff(fd, target, size)
   int fd ;
   register char *target ;
   unsigned size ;
{
   register int r ;
   unsigned entry_size = size ;

   while (size)
      switch (r = read(fd, target, size))
      {
	 case -1:
	    errmsg(errno, "read error") ;
	    mawk_exit(2) ;

	 case 0:
	    goto out ;

	 default:
	    target += r ; size -= r ;
	    break ;
      }

out :
   *target = 0 ;
   return entry_size - size ;
}

/* main_fin is a handle to the main input stream
   == 0	 never been opened   */

FIN *main_fin ;
ARRAY Argv ;			 /* to the user this is ARGV  */
static double argi = 1.0 ;	 /* index of next ARGV[argi] to try to open */


static void
set_main_to_stdin()
{
   cell_destroy(FILENAME) ;
   FILENAME->type = C_STRING ;
   FILENAME->ptr = (PTR) new_STRING("-") ;
   cell_destroy(FNR) ;
   FNR->type = C_DOUBLE ;
   FNR->dval = 0.0 ; rt_fnr = 0 ;
   main_fin = FINdopen(0, 1) ;
}


/* this gets called once to get the input stream going.
   It is called after the execution of the BEGIN block
   unless there is a getline inside BEGIN {}
*/
void
open_main()
{
   CELL argc ;

#if  MSDOS
   int k = binmode() ;

   if (k & 1)  setmode(0, O_BINARY) ;
   if ( k & 2 ) { setmode(1,O_BINARY) ; setmode(2,O_BINARY) ; }
#endif

   cellcpy(&argc, ARGC) ;
   if (argc.type != C_DOUBLE)  cast1_to_d(&argc) ;

   if (argc.dval == 1.0)  set_main_to_stdin() ;
   else	 next_main(1) ;
}

/* get the next command line file open */
static FIN *
next_main(open_flag)
   int open_flag ;		 /* called by open_main() if on */
{
   register CELL *cp ;
   CELL argc ;			 /* copy of ARGC */
   CELL c_argi ;		 /* cell copy of argi */
   CELL argval ;		 /* copy of ARGV[c_argi] */


   argval.type = C_NOINIT ;
   c_argi.type = C_DOUBLE ;

   if (main_fin)  FINclose(main_fin) ;
   /* FILENAME and FNR don't change unless we really open
     a new file */

   /* make a copy of ARGC to avoid side effect */
   if (cellcpy(&argc, ARGC)->type != C_DOUBLE)	cast1_to_d(&argc) ;

   while (argi < argc.dval)
   {
      c_argi.dval = argi ;
      argi += 1.0 ;

      if (!(cp = array_find(Argv, &c_argi, NO_CREATE)))
	 continue ;		 /* its deleted */

      /* make a copy so we can cast w/o side effect */
      cell_destroy(&argval) ;
      cp = cellcpy(&argval, cp) ;
      if (cp->type < C_STRING)	cast1_to_s(cp) ;
      if (string(cp)->len == 0)	 continue ;
      /* file argument is "" */

      /* it might be a command line assignment */
      if (is_cmdline_assign(string(cp)->str))  continue ;

      /* try to open it -- we used to continue on failure,
       but posix says we should quit */
      if (!(main_fin = FINopen(string(cp)->str, 1)))  
      {
         errmsg(errno, "cannot open %s", string(cp)->str) ;
	 mawk_exit(2) ;
      }

      /* success -- set FILENAME and FNR */
      cell_destroy(FILENAME) ;
      cellcpy(FILENAME, cp) ;
      free_STRING(string(cp)) ;
      cell_destroy(FNR) ;
      FNR->type = C_DOUBLE ;
      FNR->dval = 0.0 ; rt_fnr = 0 ;

      return main_fin ;
   }
   /* failure */
   cell_destroy(&argval) ;

   if (open_flag)
   {
      /* all arguments were null or assignment */
      set_main_to_stdin() ;
      return main_fin ;
   }

   /* real failure */
   {
      /* this is how we mark EOF on main_fin  */
      static char dead_buff = 0 ;
      static FIN dead_main =
      {0, (FILE *) 0, &dead_buff, &dead_buff,
       1, EOF_FLAG} ;

      return main_fin = &dead_main ;
      /* since MAIN_FLAG is not set, FINgets won't call next_main() */
   }
}


int
is_cmdline_assign(s)
   char *s ;
{
   register char *p ;
   int c ;
   SYMTAB *stp ;
   CELL *cp ;
   unsigned len ;
   CELL cell ;			 /* used if command line assign to pseudo field */
   CELL *fp = (CELL *) 0 ;	 /* ditto */

   if (scan_code[*(unsigned char *) s] != SC_IDCHAR)  return 0 ;

   p = s + 1 ;
   while ((c = scan_code[*(unsigned char *) p]) == SC_IDCHAR
	  || c == SC_DIGIT)
      p++ ;

   if (*p != '=')  return 0 ;

   *p = 0 ;
   stp = find(s) ;

   switch (stp->type)
   {
      case ST_NONE:
	 stp->type = ST_VAR ;
	 stp->stval.cp = cp = ZMALLOC(CELL) ;
	 break ;

      case ST_VAR:
      case ST_NR:		/* !! no one will do this */
	 cp = stp->stval.cp ;
	 cell_destroy(cp) ;
	 break ;

      case ST_FIELD:
	 /* must be pseudo field */
	 fp = stp->stval.cp ;
	 cp = &cell ;
	 break ;

      default:
	 rt_error(
	 "cannot command line assign to %s\n\ttype clash or keyword"
		    ,s) ;
   }

   /* we need to keep ARGV[i] intact */
   *p++ = '=' ;
   len = strlen(p) + 1 ;
   /* posix says escape sequences are on from command line */
   p = rm_escape(strcpy((char *) zmalloc(len), p)) ;
   cp->ptr = (PTR) new_STRING(p) ;
   zfree(p, len) ;
   check_strnum(cp) ;		 /* sets cp->type */
   if (fp)			/* move it from cell to pfield[] */
   {
      field_assign(fp, cp) ;
      free_STRING(string(cp)) ;
   }
   return 1 ;
}