bash/examples/loadables/lcut.c

/* lcut - extract specified fields from a line and assign them to an array or
	  print them to the standard output */

/*
   Copyright (C) 2020,2022,2023 Free Software Foundation, Inc.

   Bash is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   Bash is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with Bash.  If not, see <http://www.gnu.org/licenses/>.
*/

/* See Makefile for compilation details. */

#include <config.h>

#if defined (HAVE_UNISTD_H)
#  include <unistd.h>
#endif
#include "bashansi.h"
#include <stdio.h>

#include "loadables.h"
#include "shmbutil.h"

#define CUT_ARRAY_DEFAULT	"CUTFIELDS"

#define NOPOS	-2		/* sentinel for unset startpos/endpos */

#define BOL	0		
#define EOL	INT_MAX
#define NORANGE	-1		/* just a position, no range */

#define BFLAG	(1 << 0)
#define CFLAG	(1 << 1)
#define DFLAG	(1 << 2)
#define FFLAG	(1 << 3)
#define SFLAG	(1 << 4)

struct cutpos
{
  int startpos, endpos;		/* zero-based, correction done in getlist() */
};

struct cutop
{
  int flags;
  int delim;
  int npos;
  struct cutpos *poslist;
};

static int
poscmp (const void *a, const void *b)
{
  struct cutpos *p1, *p2;

  p1 = (struct cutpos *)a;
  p2 = (struct cutpos *)b;
  return (p1->startpos - p2->startpos);
}

static int
getlist (char *arg, struct cutpos **opp)
{
  char *ntok, *ltok, *larg;
  int s, e;
  intmax_t num;
  struct cutpos *poslist;
  int npos, nsize;

  poslist = 0;
  nsize = npos = 0;
  s = e = 0;
  larg = arg;
  while (ltok = strsep (&larg, ","))
    {
      if (*ltok == 0)
        continue;

      ntok = strsep (&ltok, "-");
      if (*ntok == 0)
        s = BOL;
      else
	{
	  if (valid_number (ntok, &num) == 0 || (int)num != num || num <= 0)
	    {
	      builtin_error ("%s: invalid list value", ntok);
	      *opp = poslist;
	      return -1;
	    }
	  s = num;
	  s--;		/* fields are 1-based */
	}
      if (ltok == 0)
	e = NORANGE;
      else if (*ltok == 0)
	e = EOL;
      else
	{
	  if (valid_number (ltok, &num) == 0 || (int)num != num || num <= 0)
	    {
	      builtin_error ("%s: invalid list value", ltok);
	      *opp = poslist;
	      return -1;
	    }
	  e = num;
	  e--;
	  if (e == s)
	    e = NORANGE;
	}

      if (npos == nsize)
	{
	  nsize += 4;
	  poslist = (struct cutpos *)xrealloc (poslist, nsize * sizeof (struct cutpos));
	}
      poslist[npos].startpos = s;
      poslist[npos].endpos = e; 
      npos++;
    }
  if (npos == 0)
    {
      builtin_error ("missing list of positions");
      *opp = poslist;
      return -1;
    }

  qsort (poslist, npos, sizeof(poslist[0]), poscmp);
  *opp = poslist;

  return npos;
}

static int
cutbytes (SHELL_VAR *v, char *line, struct cutop *ops)
{
  arrayind_t ind;
  char *buf, *bmap;
  size_t llen;
  int i, b, n, s, e;

  llen = strlen (line);
  buf = xmalloc (llen + 1);
  bmap = xmalloc (llen + 1);
  memset (bmap, 0, llen);

  for (n = 0; n < ops->npos; n++)
    {
      s = ops->poslist[n].startpos;		/* no translation needed yet */
      e = ops->poslist[n].endpos;
      if (e == NORANGE)
        e = s;
      else if (e == EOL || e >= llen)
	e = llen - 1;
      /* even if a column is specified multiple times, it will only be printed
         once */
      for (i = s; i <= e; i++)
	bmap[i] = 1;
    }

  b = 0;
  for (i = 0; i < llen; i++)
    if (bmap[i])
      buf[b++] = line[i];
  buf[b] = 0; 

  if (v)
    {
      ind = 0;
      bind_array_element (v, ind, buf, 0);
      ind++;
    }
  else
    printf ("%s\n", buf);

  free (buf);
  free (bmap);

  return ind;
}

static int
cutchars (SHELL_VAR *v, char *line, struct cutop *ops)
{
  arrayind_t ind;
  char *buf, *bmap;
  wchar_t *wbuf, *wb2;
  size_t llen, wlen;
  int i, b, n, s, e;

  if (MB_CUR_MAX == 1)
    return (cutbytes (v, line, ops));
  if (locale_utf8locale && utf8_mbsmbchar (line) == 0)
    return (cutbytes (v, line, ops));

  llen = strlen (line);
  wbuf = (wchar_t *)xmalloc ((llen + 1) * sizeof (wchar_t));

  wlen = mbstowcs (wbuf, line, llen);
  if (MB_INVALIDCH (wlen))
    {
      free (wbuf);
      return (cutbytes (v, line, ops));
    }

  bmap = xmalloc (llen + 1);
  memset (bmap, 0, llen);
  
  for (n = 0; n < ops->npos; n++)
    {
      s = ops->poslist[n].startpos;		/* no translation needed yet */
      e = ops->poslist[n].endpos;
      if (e == NORANGE)
        e = s;
      else if (e == EOL || e >= wlen)
	e = wlen - 1;
      /* even if a column is specified multiple times, it will only be printed
         once */
      for (i = s; i <= e; i++)
	bmap[i] = 1;
    }

  wb2 = (wchar_t *)xmalloc ((wlen + 1) * sizeof (wchar_t));
  b = 0;
  for (i = 0; i < wlen; i++)
    if (bmap[i])
      wb2[b++] = wbuf[i];
  wb2[b] = 0;

  free (wbuf);

  buf = bmap;
  n = wcstombs (buf, wb2, llen);

  if (v)
    {
      ind = 0;
      bind_array_element (v, ind, buf, 0);
      ind++;
    }
  else
    printf ("%s\n", buf);

  free (buf);
  free (wb2);

  return ind;
}

/* The basic strategy is to cut the line into fields using strsep, populate
   an array of fields from 0..nf, then select those fields using the same
   bitmap approach as cut{bytes,chars} and assign them to the array variable
   V or print them on stdout. This function obeys SFLAG. */
static int
cutfields (SHELL_VAR *v, char *line, struct cutop *ops)
{
  arrayind_t ind;
  char *buf, *bmap, *field, **fields, delim[2];
  size_t llen, fsize;
  int i, b, n, s, e, nf;

  ind = 0;

  delim[0] = ops->delim;
  delim[1] = '\0';

  fields = 0;
  nf = 0;
  fsize = 0;

  field = buf = line;
  do
    {
      field = strsep (&buf, delim);	/* destructive */
      if (nf == fsize)
	{
	  fsize += 8;
	  fields = xrealloc (fields, fsize * sizeof (char *));
	}
      fields[nf] = field;
      if (field)
	nf++;
    }
  while (field);

  if (nf == 1)
    {
      free (fields);
      if (ops->flags & SFLAG)
	return ind;
      if (v)
	{
	  bind_array_element (v, ind, line, 0);
	  ind++;
	}
      else
	printf ("%s\n", line);
      return ind;
    }

  bmap = xmalloc (nf + 1);
  memset (bmap, 0, nf);

  for (n = 0; n < ops->npos; n++)
    {
      s = ops->poslist[n].startpos;		/* no translation needed yet */
      e = ops->poslist[n].endpos;
      if (e == NORANGE)
        e = s;
      else if (e == EOL || e >= nf)
	e = nf - 1;
      /* even if a column is specified multiple times, it will only be printed
         once */
      for (i = s; i <= e; i++)
	bmap[i] = 1;
    }

  for (i = 1, b = 0; b < nf; b++)
    {
      if (bmap[b] == 0)
	continue;
      if (v)
	{
	  bind_array_element (v, ind, fields[b], 0);
	  ind++;
	}
      else
	{
	  if (i == 0)
	    putchar (ops->delim);
	  printf ("%s", fields[b]);
	}
      i = 0;
    }
  if (v == 0)
    putchar ('\n');

  return nf;
}

static int
cutline (SHELL_VAR *v, char *line, struct cutop *ops)
{
  int rval;

  if (ops->flags & BFLAG)
    rval = cutbytes (v, line, ops);
  else if (ops->flags & CFLAG)
    rval = cutchars (v, line, ops);
  else
    rval = cutfields (v, line, ops);

  return (rval >= 0 ? EXECUTION_SUCCESS : EXECUTION_FAILURE);
}

static int
cutfile (SHELL_VAR *v, WORD_LIST *list, struct cutop *ops)
{
}

#define OPTSET(x)	     ((cutflags & (x)) ? 1 : 0)

static int
cut_internal (int which, WORD_LIST *list)
{
  int opt, rval, cutflags, delim, npos;
  char *array_name, *cutstring, *list_arg;
  SHELL_VAR *v;
  struct cutop op;
  struct cutpos *poslist;

  v = 0;
  rval = EXECUTION_SUCCESS;

  cutflags = 0;
  array_name = 0;
  list_arg = 0;
  delim = '\t';

  reset_internal_getopt ();
  while ((opt = internal_getopt (list, "a:b:c:d:f:sn")) != -1)
    {
      switch (opt)
	{
	case 'a':
	  array_name = list_optarg;
	  break;
	case 'b':
	  cutflags |= BFLAG;
	  list_arg = list_optarg;
	  break;
	case 'c':
	  cutflags |= CFLAG;
	  list_arg = list_optarg;
	  break;
	case 'd':
	  cutflags |= DFLAG;
	  delim = list_optarg[0];
	  if (delim == 0 || list_optarg[1])
	    {
	      builtin_error ("delimiter must be a single non-null character");
	      return (EX_USAGE);
	    }
	  break;
	case 'f':
	  cutflags |= FFLAG;
	  list_arg = list_optarg;
	  break;
	case 'n':
	  break;
	case 's':
	  cutflags |= SFLAG;
	  break;
	CASE_HELPOPT;
	default:
	  builtin_usage ();
	  return (EX_USAGE);
	}
    }
  list = loptend;

  if (array_name && (valid_identifier (array_name) == 0))
    {
      sh_invalidid (array_name);
      return (EXECUTION_FAILURE);
    }

  if (list == 0 && which == 0)
    {
      builtin_error ("string argument required");
      return (EX_USAGE);
    }

  /* options are mutually exclusive and one is required */
  if ((OPTSET (BFLAG) + OPTSET (CFLAG) + OPTSET (FFLAG)) != 1)
    {
      builtin_usage ();
      return (EX_USAGE);
    }

  if ((npos = getlist (list_arg, &poslist)) < 0)
    {
      free (poslist);
      return (EXECUTION_FAILURE);
    }

  if (array_name)
    {      
      v = find_or_make_array_variable (array_name, 1);
      if (v == 0 || readonly_p (v) || noassign_p (v))
	{
	  if (v && readonly_p (v))
	    err_readonly (array_name);
	  return (EXECUTION_FAILURE);
	}
      else if (array_p (v) == 0)
	{
	  builtin_error ("%s: not an indexed array", array_name);
	  return (EXECUTION_FAILURE);
	}
      if (invisible_p (v))
	VUNSETATTR (v, att_invisible);
      array_flush (array_cell (v));
    }

  cutstring = list->word->word;

  if (cutstring == 0 || *cutstring == 0)
    {
      free (poslist);
      return (EXECUTION_SUCCESS);
    }

  op.flags = cutflags;
  op.delim = delim;
  op.npos = npos;
  op.poslist = poslist;

  if (which == 0)
    rval = cutline (v, cutstring, &op);

  return (rval);
}

int
lcut_builtin (WORD_LIST *list)
{
  return (cut_internal (0, list));
}

char *lcut_doc[] = {
	"Extract selected fields from a string.",
	"",
        "Select portions of LINE (as specified by LIST) and assign them to",
        "elements of the indexed array ARRAY starting at index 0, or write",
        "them to the standard output if -a is not specified.",
        "",
	"Items specified by LIST are either column positions or fields delimited",
	"by a special character, and are described more completely in cut(1).",
	"",
	"Columns correspond to bytes (-b), characters (-c), or fields (-f). The",
	"field delimiter is specified by -d (default TAB). Column numbering",
	"starts at 1.",
	(char *)NULL
};

struct builtin lcut_struct = {
	"lcut",			/* builtin name */
	lcut_builtin,		/* function implementing the builtin */
	BUILTIN_ENABLED,	/* initial flags for builtin */
	lcut_doc,		/* array of long documentation strings. */
	"lcut [-a ARRAY] [-b LIST] [-c LIST] [-f LIST] [-d CHAR] [-sn] line",	/* usage synopsis; becomes short_doc */
	0			/* reserved for internal use */
};