commit bash-20200413 snapshot

examples/loadables/Makefile.in

@@ -103,7 +103,7 @@ INC = -I. -I.. -I$(topdir) -I$(topdir)/lib -I$(topdir)/builtins -I${srcdir} \
 ALLPROG = print truefalse sleep finfo logname basename dirname fdflags \
 	  tty pathchk tee head mkdir rmdir mkfifo mktemp printenv id whoami \
 	  uname sync push ln unlink realpath strftime mypid setpgid seq rm \
-	  accept
+	  accept csv cut
 OTHERPROG = necho hello cat pushd stat
 
 all:	$(SHOBJ_STATUS)
@@ -215,6 +215,12 @@ unlink:	unlink.o
 realpath:	realpath.o
 	$(SHOBJ_LD) $(SHOBJ_LDFLAGS) $(SHOBJ_XLDFLAGS) -o $@ realpath.o $(SHOBJ_LIBS)
 
+csv:	csv.o
+	$(SHOBJ_LD) $(SHOBJ_LDFLAGS) $(SHOBJ_XLDFLAGS) -o $@ csv.o $(SHOBJ_LIBS)
+
+cut:	cut.o
+	$(SHOBJ_LD) $(SHOBJ_LDFLAGS) $(SHOBJ_XLDFLAGS) -o $@ cut.o $(SHOBJ_LIBS)
+
 strftime:	strftime.o
 	$(SHOBJ_LD) $(SHOBJ_LDFLAGS) $(SHOBJ_XLDFLAGS) -o $@ strftime.o $(SHOBJ_LIBS)
 
@@ -296,6 +302,8 @@ rmdir.o: rmdir.c
 necho.o: necho.c
 hello.o: hello.c
 cat.o: cat.c
+csv.o: csv.c
+cut.o: cut.c
 printenv.o: printenv.c
 id.o: id.c
 whoami.o: whoami.c

examples/loadables/csv.c

@@ -0,0 +1,206 @@
+/* csv - process a line of csv data and populate an indexed array with the
+	 fields */
+
+/*
+   Copyright (C) 2020 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"
+
+#define CSV_ARRAY_DEFAULT	"CSV"
+
+#define NQUOTE	0
+#define DQUOTE	1
+
+/* Split LINE into comma-separated fields, storing each field into a separate
+   element of array variable CSV, starting at index 0. The format of LINE is
+   as described in RFC 4180. */
+static int
+csvsplit (csv, line)
+     SHELL_VAR *csv;
+     char *line;
+{
+  arrayind_t ind;
+  char *field, *prev, *buf, *xbuf;
+  int delim, qstate;
+  int b, rval;
+
+  xbuf = 0;
+  ind = 0;
+  field = prev = line;
+
+  do
+    {
+      if (*prev == '"')
+	{
+	  if (xbuf == 0)
+	    xbuf = xmalloc (strlen (prev) + 1);
+	  buf = xbuf;
+	  b = 0;
+	  qstate = DQUOTE;
+	  for (field = ++prev; *field; field++)
+	    {
+	      if (qstate == DQUOTE && *field == '"' && field[1] == '"')
+		buf[b++] = *field++;	/* skip double quote */
+	      else if (qstate == DQUOTE && *field == '"')
+	        qstate = NQUOTE;
+	      else if (qstate == NQUOTE && *field == ',')
+		break;
+	      else
+		/* This copies any text between a closing double quote and the
+		   delimiter. If you want to change that, make sure to do the
+		   copy only if qstate == DQUOTE. */
+		buf[b++] = *field;
+	    }
+	  buf[b] = '\0';
+	}
+      else
+	{
+	  buf = prev;
+	  field = prev + strcspn (prev, ",");
+	}
+
+      delim = *field;
+      *field = '\0';
+
+      bind_array_element (csv, ind, buf, 0);
+      ind++;
+
+      *field = delim;
+
+      if (delim == ',')
+	prev = field + 1;
+    }
+  while (delim == ',');
+
+  if (xbuf)
+    free (xbuf);
+
+  return (rval = ind);				/* number of fields */
+}
+
+int
+csv_builtin (list)
+     WORD_LIST *list;
+{
+  int opt, rval;
+  char *array_name, *csvstring;
+  SHELL_VAR *v;
+
+  array_name = 0;
+  rval = EXECUTION_SUCCESS;
+
+  reset_internal_getopt ();
+  while ((opt = internal_getopt (list, "a:")) != -1)
+    {
+      switch (opt)
+	{
+	case 'a':
+	  array_name = list_optarg;
+	  break;
+	CASE_HELPOPT;
+	default:
+	  builtin_usage ();
+	  return (EX_USAGE);
+	}
+    }
+  list = loptend;
+
+  if (array_name == 0)
+    array_name = CSV_ARRAY_DEFAULT;
+
+  if (legal_identifier (array_name) == 0)
+    {
+      sh_invalidid (array_name);
+      return (EXECUTION_FAILURE);
+    }
+
+  if (list == 0)
+    {
+      builtin_error ("csv string argument required");
+      return (EX_USAGE);
+    }
+
+  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));
+
+  csvstring = list->word->word;
+
+  if (csvstring == 0 || *csvstring == 0)
+    return (EXECUTION_SUCCESS);
+
+  opt = csvsplit (v, csvstring);
+  /* Maybe do something with OPT here, it's the number of fields */
+
+  return (rval);
+}
+
+/* Called when builtin is enabled and loaded from the shared object.  If this
+   function returns 0, the load fails. */
+int
+csv_builtin_load (name)
+     char *name;
+{
+  return (1);
+}
+
+/* Called when builtin is disabled. */
+void
+csv_builtin_unload (name)
+     char *name;
+{
+}
+
+char *csv_doc[] = {
+	"Read comma-separated fields from a string.",
+	"",
+	"Parse STRING, a line of comma-separated values, into individual fields,",
+	"and store them into the indexed array ARRAYNAME starting at index 0.",
+	"If ARRAYNAME is not supplied, \"CSV\" is the default array name.",
+	(char *)NULL
+};
+
+struct builtin csv_struct = {
+	"csv",			/* builtin name */
+	csv_builtin,		/* function implementing the builtin */
+	BUILTIN_ENABLED,	/* initial flags for builtin */
+	csv_doc,		/* array of long documentation strings. */
+	"csv [-a ARRAY] string",	/* usage synopsis; becomes short_doc */
+	0			/* reserved for internal use */
+};

examples/loadables/cut.c

@@ -0,0 +1,641 @@
+/* lcut - extract specified fields from a line and assign them to an array or
+	  print them to the standard output */
+
+/*
+   Copyright (C) 2020 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 <fcntl.h>
+#include <errno.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 (a, b)
+     void *a, *b;
+{
+  struct cutpos *p1, *p2;
+
+  p1 = (struct cutpos *)a;
+  p2 = (struct cutpos *)b;
+  return (p1->startpos - p2->startpos);
+}
+
+static int
+getlist (arg, opp)
+     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 (legal_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 (legal_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 (v, line, ops)
+     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 (v, line, ops)
+     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 (v, line, ops)
+     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 (v, line, ops)
+     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 (v, list, ops)
+     SHELL_VAR *v;
+     WORD_LIST *list;
+     struct cutop *ops;
+{
+  int fd, unbuffered_read;
+  char *line, *b;
+  size_t llen;
+  WORD_LIST *l;
+  ssize_t n;
+
+  line = 0;
+  llen = 0;
+
+  l = list;
+  do
+    {
+      /* for each file */
+      if (l == 0 || (l->word->word[0] == '-' && l->word->word[1] == '\0'))
+	fd = 0;
+      else
+	fd = open (l->word->word, O_RDONLY);
+      if (fd < 0)
+	{
+	  file_error (l->word->word);
+	  return (EXECUTION_FAILURE);
+	}
+
+#ifndef __CYGWIN__
+      unbuffered_read = (lseek (fd, 0L, SEEK_CUR) < 0) && (errno == ESPIPE);
+#else
+      unbuffered_read = 1;
+#endif
+
+      while ((n = zgetline (fd, &line, &llen, '\n', unbuffered_read)) != -1)
+	  cutline (v, line, ops);		/* can modify line */
+      if (fd > 0)
+	close (fd);
+
+      if (l)
+	l = l->next;
+    }
+  while (l);
+
+  free (line);
+  return EXECUTION_SUCCESS;
+}
+
+#define OPTSET(x)	     ((cutflags & (x)) ? 1 : 0)
+
+static int
+cut_internal (which, list)
+     int which;				/* not used yet */
+     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 && (legal_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));
+    }
+
+  op.flags = cutflags;
+  op.delim = delim;
+  op.npos = npos;
+  op.poslist = poslist;
+
+  /* we implement cut as a builtin with a cutfile() function that opens each
+     filename in LIST as a filename (or `-' for stdin) and runs cutline on
+     every line in the file. */
+  if (which == 0)
+    {
+      cutstring = list->word->word;
+      if (cutstring == 0 || *cutstring == 0)
+	{
+	  free (poslist);
+	  return (EXECUTION_SUCCESS);
+	}
+      rval = cutline (v, cutstring, &op);
+    }
+  else
+    rval = cutfile (v, list, &op);
+
+  return (rval);
+}
+
+int
+lcut_builtin (list)
+     WORD_LIST *list;
+{
+  return (cut_internal (0, list));
+}
+
+int
+cut_builtin (list)
+     WORD_LIST *list;
+{
+  return (cut_internal (1, list));
+}
+
+/* Called when builtin is enabled and loaded from the shared object.  If this
+   function returns 0, the load fails. */
+int
+lcut_builtin_load (name)
+     char *name;
+{
+  return (1);
+}
+
+/* Called when builtin is disabled. */
+void
+lcut_builtin_unload (name)
+     char *name;
+{
+}
+
+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 */
+};
+
+char *cut_doc[] = {
+	"Extract selected fields from each line of a file.",
+	"",
+        "Select portions of each line (as specified by LIST) from each FILE",
+        "and write them to the standard output. cut reads from the standard",
+        "input if no FILE arguments are specified or if a FILE argument is a",
+        "single hyphen.",
+        "",
+	"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 cut_struct = {
+	"cut",			/* builtin name */
+	cut_builtin,		/* function implementing the builtin */
+	BUILTIN_ENABLED,	/* initial flags for builtin */
+	cut_doc,		/* array of long documentation strings. */
+	"cut [-a ARRAY] [-b LIST] [-c LIST] [-f LIST] [-d CHAR] [-sn] [file ...]",	/* usage synopsis; becomes short_doc */
+	0			/* reserved for internal use */
+};

examples/loadables/lcut.c

@@ -0,0 +1,563 @@
+/* lcut - extract specified fields from a line and assign them to an array or
+	  print them to the standard output */
+
+/*
+   Copyright (C) 2020 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 (a, b)
+     void *a, *b;
+{
+  struct cutpos *p1, *p2;
+
+  p1 = (struct cutpos *)a;
+  p2 = (struct cutpos *)b;
+  return (p1->startpos - p2->startpos);
+}
+
+static int
+getlist (arg, opp)
+     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 (legal_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 (legal_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 (v, line, ops)
+     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 (v, line, ops)
+     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 (v, line, ops)
+     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 (v, line, ops)
+     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 (v, list, ops)
+     SHELL_VAR *v;
+     WORD_LIST *list;
+     struct cutop *ops;
+{
+}
+
+#define OPTSET(x)	     ((cutflags & (x)) ? 1 : 0)
+
+static int
+cut_internal (which, list)
+     int which;				/* not used yet */
+     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 && (legal_identifier (array_name) == 0))
+    {
+      sh_invalidid (array_name);
+      return (EXECUTION_FAILURE);
+    }
+
+  if (list == 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;
+
+  /* we can eventually implement cut as a builtin with a cutfile() function
+     that opens cutstring as a filename (or `-' for stdin) and runs cutline
+     on every line in the file. */
+  if (which == 0)
+    rval = cutline (v, cutstring, &op);
+
+  return (rval);
+}
+
+int
+lcut_builtin (list)
+     WORD_LIST *list;
+{
+  return (cut_internal (0, list));
+}
+
+/* Called when builtin is enabled and loaded from the shared object.  If this
+   function returns 0, the load fails. */
+int
+lcut_builtin_load (name)
+     char *name;
+{
+  return (1);
+}
+
+/* Called when builtin is disabled. */
+void
+lcut_builtin_unload (name)
+     char *name;
+{
+}
+
+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 */
+};