[deliverable/binutils-gdb.git] / gdb / command.c

/* Library for reading command lines and decoding commands.
   Copyright (C) 1986, 1989, 1990 Free Software Foundation, Inc.

   This program 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 1, or (at your option)
   any later version.

   This program 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 this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */

#include "defs.h"
#include "command.h"
#include "symtab.h"
#include "value.h"
#include <stdio.h>
#include <ctype.h>
#include <string.h>

extern char *getenv ();

/* Add element named NAME to command list *LIST.
   FUN should be the function to execute the command;
   it will get a character string as argument, with leading
   and trailing blanks already eliminated.

   DOC is a documentation string for the command.
   Its first line should be a complete sentence.
   It should start with ? for a command that is an abbreviation
   or with * for a command that most users don't need to know about.  */

struct cmd_list_element *
add_cmd (name, class, fun, doc, list)
     char *name;
     enum command_class class;
     void (*fun) ();
     char *doc;
     struct cmd_list_element **list;
{
  register struct cmd_list_element *c
    = (struct cmd_list_element *) xmalloc (sizeof (struct cmd_list_element));

  delete_cmd (name, list);
  c->next = *list;
  c->name = name;
  c->class = class;
  c->function = fun;
  c->doc = doc;
  c->prefixlist = 0;
  c->prefixname = (char *)NULL;
  c->allow_unknown = 0;
  c->abbrev_flag = 0;
  c->aux = 0;
  c->type = not_set_cmd;
  c->completer = make_symbol_completion_list;
  c->var = 0;
  c->var_type = var_boolean;
  c->user_commands = 0;
  *list = c;
  return c;
}

/* Same as above, except that the abbrev_flag is set. */

struct cmd_list_element *
add_abbrev_cmd (name, class, fun, doc, list)
     char *name;
     enum command_class class;
     void (*fun) ();
     char *doc;
     struct cmd_list_element **list;
{
  register struct cmd_list_element *c
    = add_cmd (name, class, fun, doc, list);

  c->abbrev_flag = 1;
  return c;
}

struct cmd_list_element *
add_alias_cmd (name, oldname, class, abbrev_flag, list)
     char *name;
     char *oldname;
     enum command_class class;
     int abbrev_flag;
     struct cmd_list_element **list;
{
  /* Must do this since lookup_cmd tries to side-effect its first arg */
  char *copied_name;
  register struct cmd_list_element *old;
  register struct cmd_list_element *c;
  copied_name = (char *) alloca (strlen (oldname) + 1);
  strcpy (copied_name, oldname);
  old  = lookup_cmd (&copied_name, *list, "", 1, 1);

  if (old == 0)
    {
      delete_cmd (name, list);
      return 0;
    }

  c = add_cmd (name, class, old->function, old->doc, list);
  c->prefixlist = old->prefixlist;
  c->prefixname = old->prefixname;
  c->allow_unknown = old->allow_unknown;
  c->abbrev_flag = abbrev_flag;
  c->aux = old->aux;
  return c;
}

/* Like add_cmd but adds an element for a command prefix:
   a name that should be followed by a subcommand to be looked up
   in another command list.  PREFIXLIST should be the address
   of the variable containing that list.  */

struct cmd_list_element *
add_prefix_cmd (name, class, fun, doc, prefixlist, prefixname,
                allow_unknown, list)
     char *name;
     enum command_class class;
     void (*fun) ();
     char *doc;
     struct cmd_list_element **prefixlist;
     char *prefixname;
     int allow_unknown;
     struct cmd_list_element **list;
{
  register struct cmd_list_element *c = add_cmd (name, class, fun, doc, list);
  c->prefixlist = prefixlist;
  c->prefixname = prefixname;
  c->allow_unknown = allow_unknown;
  return c;
}

/* Like add_prefix_cmd butsets the abbrev_flag on the new command. */
   
struct cmd_list_element *
add_abbrev_prefix_cmd (name, class, fun, doc, prefixlist, prefixname,
                allow_unknown, list)
     char *name;
     enum command_class class;
     void (*fun) ();
     char *doc;
     struct cmd_list_element **prefixlist;
     char *prefixname;
     int allow_unknown;
     struct cmd_list_element **list;
{
  register struct cmd_list_element *c = add_cmd (name, class, fun, doc, list);
  c->prefixlist = prefixlist;
  c->prefixname = prefixname;
  c->allow_unknown = allow_unknown;
  c->abbrev_flag = 1;
  return c;
}

void
not_just_help_class_command (args, from_tty, c)
     char *args;
     int from_tty;
     struct cmd_list_element *c;
{
}

/* Add element named NAME to command list LIST (the list for set
   or some sublist thereof).
   CLASS is as in add_cmd.
   VAR_TYPE is the kind of thing we are setting.
   VAR is address of the variable being controlled by this command.
   DOC is the documentation string.  */
struct cmd_list_element *
add_set_cmd (name, class, var_type, var, doc, list)
     char *name;
     enum command_class class;
     var_types var_type;
     char *var;
     char *doc;
     struct cmd_list_element **list;
{
  /* For set/show, we have to call do_setshow_command
     differently than an ordinary function (take commandlist as
     well as arg), so the function field isn't helpful.  However,
     function == NULL means that it's a help class, so set the function
     to not_just_help_class_command.  */
  struct cmd_list_element *c
    = add_cmd (name, class, not_just_help_class_command, doc, list);

  c->type = set_cmd;
  c->var_type = var_type;
  c->var = var;
  return c;
}

/* Where SETCMD has already been added, add the corresponding show
   command to LIST and return a pointer to it.  */
struct cmd_list_element *
add_show_from_set (setcmd, list)
     struct cmd_list_element *setcmd;
     struct cmd_list_element **list;
{
  struct cmd_list_element *showcmd =
    (struct cmd_list_element *) xmalloc (sizeof (struct cmd_list_element));

  bcopy (setcmd, showcmd, sizeof (struct cmd_list_element));
  delete_cmd (showcmd->name, list);
  showcmd->type = show_cmd;
  
  /* Replace "set " at start of docstring with "show ".  */
  if (setcmd->doc[0] == 'S' && setcmd->doc[1] == 'e'
      && setcmd->doc[2] == 't' && setcmd->doc[3] == ' ')
    showcmd->doc = concat ("Show ", setcmd->doc + 4, "");
  else
    fprintf (stderr, "GDB internal error: Bad docstring for set command\n");
  
  showcmd->next = *list;
  *list = showcmd;
  return showcmd;
}

/* Remove the command named NAME from the command list.  */

void
delete_cmd (name, list)
     char *name;
     struct cmd_list_element **list;
{
  register struct cmd_list_element *c;
  struct cmd_list_element *p;

  while (*list && !strcmp ((*list)->name, name))
    {
      p = (*list)->next;
      free (*list);
      *list = p;
    }

  if (*list)
    for (c = *list; c->next;)
      {
        if (!strcmp (c->next->name, name))
          {
            p = c->next->next;
            free (c->next);
            c->next = p;
          }
        else
          c = c->next;
      }
}

void help_cmd (), help_list (), help_cmd_list ();

/* This command really has to deal with two things:
 *     1) I want documentation on *this string* (usually called by
 * "help commandname").
 *     2) I want documentation on *this list* (usually called by
 * giving a command that requires subcommands.  Also called by saying
 * just "help".)
 *
 *   I am going to split this into two seperate comamnds, help_cmd and
 * help_list. 
 */

void
help_cmd (command, stream)
     char *command;
     FILE *stream;
{
  struct cmd_list_element *c;
  extern struct cmd_list_element *cmdlist;

  if (!command)
    {
      help_list (cmdlist, "", all_classes, stream);
      return;
    }

  c = lookup_cmd (&command, cmdlist, "", 0, 0);

  if (c == 0)
    return;

  /* There are three cases here.
     If c->prefixlist is nonzero, we have a prefix command.
     Print its documentation, then list its subcommands.
     
     If c->function is nonzero, we really have a command.
     Print its documentation and return.
     
     If c->function is zero, we have a class name.
     Print its documentation (as if it were a command)
     and then set class to the number of this class
     so that the commands in the class will be listed.  */

  fputs_filtered (c->doc, stream);
  fputs_filtered ("\n", stream);

  if (c->prefixlist == 0 && c->function != 0)
    return;
  fprintf_filtered (stream, "\n");

  /* If this is a prefix command, print it's subcommands */
  if (c->prefixlist)
    help_list (*c->prefixlist, c->prefixname, all_commands, stream);

  /* If this is a class name, print all of the commands in the class */
  if (c->function == 0)
    help_list (cmdlist, "", c->class, stream);
}

/*
 * Get a specific kind of help on a command list.
 *
 * LIST is the list.
 * CMDTYPE is the prefix to use in the title string.
 * CLASS is the class with which to list the nodes of this list (see
 * documentation for help_cmd_list below),  As usual, ALL_COMMANDS for
 * everything, ALL_CLASSES for just classes, and non-negative for only things
 * in a specific class.
 * and STREAM is the output stream on which to print things.
 * If you call this routine with a class >= 0, it recurses.
 */
void
help_list (list, cmdtype, class, stream)
     struct cmd_list_element *list;
     char *cmdtype;
     enum command_class class;
     FILE *stream;
{
  int len;
  char *cmdtype1, *cmdtype2;
  
  /* If CMDTYPE is "foo ", CMDTYPE1 gets " foo" and CMDTYPE2 gets "foo sub"  */
  len = strlen (cmdtype);
  cmdtype1 = (char *) alloca (len + 1);
  cmdtype1[0] = 0;
  cmdtype2 = (char *) alloca (len + 4);
  cmdtype2[0] = 0;
  if (len)
    {
      cmdtype1[0] = ' ';
      strncpy (cmdtype1 + 1, cmdtype, len - 1);
      cmdtype1[len] = 0;
      strncpy (cmdtype2, cmdtype, len - 1);
      strcpy (cmdtype2 + len - 1, " sub");
    }

  if (class == all_classes)
    fprintf_filtered (stream, "List of classes of %scommands:\n\n", cmdtype2);
  else
    fprintf_filtered (stream, "List of %scommands:\n\n", cmdtype2);

  help_cmd_list (list, class, cmdtype, (int)class >= 0, stream);

  if (class == all_classes)
    fprintf_filtered (stream, "\n\
Type \"help%s\" followed by a class name for a list of commands in that class.",
             cmdtype1);

  fprintf_filtered (stream, "\n\
Type \"help%s\" followed by %scommand name for full documentation.\n\
Command name abbreviations are allowed if unambiguous.\n",
           cmdtype1, cmdtype2);
}
     
/* Print only the first line of STR on STREAM.  */
static void
print_doc_line (stream, str)
     FILE *stream;
     char *str;
{
  static char *line_buffer = 0;
  static int line_size;
  register char *p;

  if (!line_buffer)
    {
      line_size = 80;
      line_buffer = (char *) xmalloc (line_size);
    }

  p = str;
  while (*p && *p != '\n' && *p != '.' && *p != ',')
    p++;
  if (p - str > line_size - 1)
    {
      line_size = p - str + 1;
      free (line_buffer);
      line_buffer = (char *) xmalloc (line_size);
    }
  strncpy (line_buffer, str, p - str);
  line_buffer[p - str] = '\0';
  if (islower (line_buffer[0]))
    line_buffer[0] = toupper (line_buffer[0]);
  fputs_filtered (line_buffer, stream);
}

/*
 * Implement a help command on command list LIST.
 * RECURSE should be non-zero if this should be done recursively on
 * all sublists of LIST.
 * PREFIX is the prefix to print before each command name.
 * STREAM is the stream upon which the output should be written.
 * CLASS should be:
 *      A non-negative class number to list only commands in that
 * class.
 *      ALL_COMMANDS to list all commands in list.
 *      ALL_CLASSES  to list all classes in list.
 *
 *   Note that RECURSE will be active on *all* sublists, not just the
 * ones seclected by the criteria above (ie. the selection mechanism
 * is at the low level, not the high-level).
 */
void
help_cmd_list (list, class, prefix, recurse, stream)
     struct cmd_list_element *list;
     enum command_class class;
     char *prefix;
     int recurse;
     FILE *stream;
{
  register struct cmd_list_element *c;

  for (c = list; c; c = c->next)
    {
      if (c->abbrev_flag == 0 &&
          (class == all_commands
          || (class == all_classes && c->function == 0)
          || (class == c->class && c->function != 0)))
        {
          fprintf_filtered (stream, "%s%s -- ", prefix, c->name);
          print_doc_line (stream, c->doc);
          fputs_filtered ("\n", stream);
        }
      if (recurse
          && c->prefixlist != 0
          && c->abbrev_flag == 0)
        help_cmd_list (*c->prefixlist, class, c->prefixname, 1, stream);
    }
}
\f
/* This routine takes a line of TEXT and a CLIST in which to
   start the lookup.  When it returns it will have incremented the text
   pointer past the section of text it matched, set *RESULT_LIST to
   the list in which the last word was matched, and will return the
   cmd list element which the text matches.  It will return 0 if no
   match at all was possible.  It will return -1 if ambigous matches are
   possible; in this case *RESULT_LIST will be set to the list in which
   there are ambiguous choices (and text will be set to the ambiguous
   text string).

   It does no error reporting whatsoever; control will always return
   to the superior routine.

   In the case of an ambiguous return (-1), *RESULT_LIST will be set to
   point at the prefix_command (ie. the best match) *or* (special
   case) will be 0 if no prefix command was ever found.  For example,
   in the case of "info a", "info" matches without ambiguity, but "a"
   could be "args" or "address", so *RESULT_LIST is set to
   the cmd_list_element for "info".  So in this case
   result list should not be interpeted as a pointer to the beginning
   of a list; it simply points to a specific command.

   If RESULT_LIST is NULL, don't set *RESULT_LIST (but don't otherwise
   affect the operation).

   This routine does *not* modify the text pointed to by TEXT.
   
   If IGNORE_HELP_CLASSES is nonzero, ignore any command list
   elements which are actually help classes rather than commands (i.e.
   the function field of the struct cmd_list_element is 0).  */

struct cmd_list_element *
lookup_cmd_1 (text, clist, result_list, ignore_help_classes)
     char **text;
     struct cmd_list_element *clist, **result_list;
     int ignore_help_classes;
{
  char *p, *command;
  int len, tmp, nfound;
  struct cmd_list_element *found, *c;

  while (**text == ' ' || **text == '\t')
    (*text)++;

  /* Treating underscores as part of command words is important
     so that "set args_foo()" doesn't get interpreted as
     "set args _foo()".  */
  for (p = *text;
       *p && (isalnum(*p) || *p == '-' || *p == '_');
       p++)
    ;

  /* If nothing but whitespace, return 0.  */
  if (p == *text)
    return 0;
  
  len = p - *text;

  /* *text and p now bracket the first command word to lookup (and
     it's length is len).  We copy this into a local temporary,
     converting to lower case as we go.  */

  command = (char *) alloca (len + 1);
  for (tmp = 0; tmp < len; tmp++)
    {
      char x = (*text)[tmp];
      command[tmp] = (x >= 'A' && x <= 'Z') ? x - 'A' + 'a' : x;
    }
  command[len] = '\0';

  /* Look it up.  */
  found = 0;
  nfound = 0;
  for (c = clist; c; c = c->next)
    if (!strncmp (command, c->name, len)
        && (!ignore_help_classes || c->function))
      {
        found = c;
        nfound++;
        if (c->name[len] == '\0')
          {
            nfound = 1;
            break;
          }
      }

  /* If nothing matches, we have a simple failure.  */
  if (nfound == 0)
    return 0;

  if (nfound > 1)
    {
      if (result_list != NULL)
        /* Will be modified in calling routine
           if we know what the prefix command is.  */
        *result_list = 0;               
      return (struct cmd_list_element *) -1; /* Ambiguous.  */
    }

  /* We've matched something on this list.  Move text pointer forward. */

  *text = p;
  if (found->prefixlist)
    {
      c = lookup_cmd_1 (text, *found->prefixlist, result_list,
                        ignore_help_classes);
      if (!c)
        {
          /* Didn't find anything; this is as far as we got.  */
          if (result_list != NULL)
            *result_list = clist;
          return found;
        }
      else if (c == (struct cmd_list_element *) -1)
        {
          /* We've gotten this far properley, but the next step
             is ambiguous.  We need to set the result list to the best
             we've found (if an inferior hasn't already set it).  */
          if (result_list != NULL)
            if (!*result_list)
              /* This used to say *result_list = *found->prefixlist
                 If that was correct, need to modify the documentation
                 at the top of this function to clarify what is supposed
                 to be going on.  */
              *result_list = found;
          return c;
        }
      else
        {
          /* We matched!  */
          return c;
        }
    }
  else
    {
      if (result_list != NULL)
        *result_list = clist;
      return found;
    }
}

/* Look up the contents of *LINE as a command in the command list LIST.
   LIST is a chain of struct cmd_list_element's.
   If it is found, return the struct cmd_list_element for that command
   and update *LINE to point after the command name, at the first argument.
   If not found, call error if ALLOW_UNKNOWN is zero
   otherwise (or if error returns) return zero.
   Call error if specified command is ambiguous,
   unless ALLOW_UNKNOWN is negative.
   CMDTYPE precedes the word "command" in the error message.

   If INGNORE_HELP_CLASSES is nonzero, ignore any command list
   elements which are actually help classes rather than commands (i.e.
   the function field of the struct cmd_list_element is 0).  */

struct cmd_list_element *
lookup_cmd (line, list, cmdtype, allow_unknown, ignore_help_classes)
     char **line;
     struct cmd_list_element *list;
     char *cmdtype;
     int allow_unknown;
     int ignore_help_classes;
{
  struct cmd_list_element *last_list = 0;
  struct cmd_list_element *c =
    lookup_cmd_1 (line, list, &last_list, ignore_help_classes);
  char *ptr = (*line) + strlen (*line) - 1;

  /* Clear off trailing whitespace.  */
  while (ptr >= *line && (*ptr == ' ' || *ptr == '\t'))
    ptr--;
  *(ptr + 1) = '\0';
  
  if (!c)
    {
      if (!allow_unknown)
        {
          if (!*line)
            error ("Lack of needed %scommand", cmdtype);
          else
            {
              char *p = *line, *q;

              while (isalnum(*p) || *p == '-')
                p++;

              q = (char *) alloca (p - *line + 1);
              strncpy (q, *line, p - *line);
              q[p-*line] = '\0';
              
              error ("Undefined %scommand: \"%s\".", cmdtype, q);
            }
        }
      else
        return 0;
    }
  else if (c == (struct cmd_list_element *) -1)
    {
      /* Ambigous.  Local values should be off prefixlist or called
         values.  */
      int local_allow_unknown = (last_list ? last_list->allow_unknown :
                                 allow_unknown);
      char *local_cmdtype = last_list ? last_list->prefixname : cmdtype;
      struct cmd_list_element *local_list =
        (last_list ? *(last_list->prefixlist) : list);
      
      if (local_allow_unknown < 0)
        {
          if (last_list)
            return last_list;   /* Found something.  */
          else
            return 0;           /* Found nothing.  */
        }
      else
        {
          /* Report as error.  */
          int amb_len;
          char ambbuf[100];

          for (amb_len = 0;
               ((*line)[amb_len] && (*line)[amb_len] != ' '
                && (*line)[amb_len] != '\t');
               amb_len++)
            ;
          
          ambbuf[0] = 0;
          for (c = local_list; c; c = c->next)
            if (!strncmp (*line, c->name, amb_len))
              {
                if (strlen (ambbuf) + strlen (c->name) + 6 < (int)sizeof ambbuf)
                  {
                    if (strlen (ambbuf))
                      strcat (ambbuf, ", ");
                    strcat (ambbuf, c->name);
                  }
                else
                  {
                    strcat (ambbuf, "..");
                    break;
                  }
              }
          error ("Ambiguous %scommand \"%s\": %s.", local_cmdtype,
                 *line, ambbuf);
          return 0;             /* lint */
        }
    }
  else
    {
      /* We've got something.  It may still not be what the caller
         wants (if this command *needs* a subcommand).  */
      while (**line == ' ' || **line == '\t')
        (*line)++;

      if (c->prefixlist && **line && !c->allow_unknown)
        error ("Undefined %scommand: \"%s\".", c->prefixname, *line);

      /* Seems to be what he wants.  Return it.  */
      return c;
    }
  return 0;
}
        
#if 0
/* Look up the contents of *LINE as a command in the command list LIST.
   LIST is a chain of struct cmd_list_element's.
   If it is found, return the struct cmd_list_element for that command
   and update *LINE to point after the command name, at the first argument.
   If not found, call error if ALLOW_UNKNOWN is zero
   otherwise (or if error returns) return zero.
   Call error if specified command is ambiguous,
   unless ALLOW_UNKNOWN is negative.
   CMDTYPE precedes the word "command" in the error message.  */

struct cmd_list_element *
lookup_cmd (line, list, cmdtype, allow_unknown)
     char **line;
     struct cmd_list_element *list;
     char *cmdtype;
     int allow_unknown;
{
  register char *p;
  register struct cmd_list_element *c, *found;
  int nfound;
  char ambbuf[100];
  char *processed_cmd;
  int i, cmd_len;

  /* Skip leading whitespace.  */

  while (**line == ' ' || **line == '\t')
    (*line)++;

  /* Clear out trailing whitespace.  */

  p = *line + strlen (*line);
  while (p != *line && (p[-1] == ' ' || p[-1] == '\t'))
    p--;
  *p = 0;

  /* Find end of command name.  */

  p = *line;
  while (*p == '-'
         || (*p >= 'a' && *p <= 'z')
         || (*p >= 'A' && *p <= 'Z')
         || (*p >= '0' && *p <= '9'))
    p++;

  /* Look up the command name.
     If exact match, keep that.
     Otherwise, take command abbreviated, if unique.  Note that (in my
     opinion) a null string does *not* indicate ambiguity; simply the
     end of the argument.  */

  if (p == *line)
    {
      if (!allow_unknown)
        error ("Lack of needed %scommand", cmdtype);
      return 0;
    }
  
  /* Copy over to a local buffer, converting to lowercase on the way.
     This is in case the command being parsed is a subcommand which
     doesn't match anything, and that's ok.  We want the original
     untouched for the routine of the original command.  */
  
  processed_cmd = (char *) alloca (p - *line + 1);
  for (cmd_len = 0; cmd_len < p - *line; cmd_len++)
    {
      char x = (*line)[cmd_len];
      if (x >= 'A' && x <= 'Z')
        processed_cmd[cmd_len] = x - 'A' + 'a';
      else
        processed_cmd[cmd_len] = x;
    }
  processed_cmd[cmd_len] = '\0';

  /* Check all possibilities in the current command list.  */
  found = 0;
  nfound = 0;
  for (c = list; c; c = c->next)
    {
      if (!strncmp (processed_cmd, c->name, cmd_len))
        {
          found = c;
          nfound++;
          if (c->name[cmd_len] == 0)
            {
              nfound = 1;
              break;
            }
        }
    }

  /* Report error for undefined command name.  */

  if (nfound != 1)
    {
      if (nfound > 1 && allow_unknown >= 0)
        {
          ambbuf[0] = 0;
          for (c = list; c; c = c->next)
            if (!strncmp (processed_cmd, c->name, cmd_len))
              {
                if (strlen (ambbuf) + strlen (c->name) + 6 < sizeof ambbuf)
                  {
                    if (strlen (ambbuf))
                      strcat (ambbuf, ", ");
                    strcat (ambbuf, c->name);
                  }
                else
                  {
                    strcat (ambbuf, "..");
                    break;
                  }
              }
          error ("Ambiguous %scommand \"%s\": %s.", cmdtype,
                 processed_cmd, ambbuf);
        }
      else if (!allow_unknown)
        error ("Undefined %scommand: \"%s\".", cmdtype, processed_cmd);
      return 0;
    }

  /* Skip whitespace before the argument.  */

  while (*p == ' ' || *p == '\t') p++;
  *line = p;

  if (found->prefixlist && *p)
    {
      c = lookup_cmd (line, *found->prefixlist, found->prefixname,
                      found->allow_unknown);
      if (c)
        return c;
    }

  return found;
}
#endif

/* Helper function for SYMBOL_COMPLETION_FUNCTION.  */

/* Return a vector of char pointers which point to the different
   possible completions in LIST of TEXT.  */

char **
complete_on_cmdlist (list, text)
     struct cmd_list_element *list;
     char *text;
{
  struct cmd_list_element *ptr;
  char **matchlist;
  int sizeof_matchlist;
  int matches;
  int textlen = strlen (text);

  sizeof_matchlist = 10;
  matchlist = (char **) xmalloc (sizeof_matchlist * sizeof (char *));
  matches = 0;

  for (ptr = list; ptr; ptr = ptr->next)
    if (!strncmp (ptr->name, text, textlen)
        && !ptr->abbrev_flag
        && (ptr->function
            || ptr->prefixlist))
      {
        if (matches == sizeof_matchlist)
          {
            sizeof_matchlist *= 2;
            matchlist = (char **) xrealloc ((char *)matchlist,
                                            (sizeof_matchlist
                                             * sizeof (char *)));
          }

        matchlist[matches] = (char *) 
          xmalloc (strlen (ptr->name) + 1);
        strcpy (matchlist[matches++], ptr->name);
      }

  if (matches == 0)
    {
      free (matchlist);
      matchlist = 0;
    }
  else
    {
      matchlist = (char **) xrealloc ((char *)matchlist, ((matches + 1)
                                                * sizeof (char *)));
      matchlist[matches] = (char *) 0;
    }

  return matchlist;
}

static int
parse_binary_operation (arg)
     char *arg;
{
  int length;

  if (!arg || !*arg)
    return 1;

  length = strlen (arg);

  while (arg[length - 1] == ' ' || arg[length - 1] == '\t')
    length--;

  if (!strncmp (arg, "on", length)
      || !strncmp (arg, "1", length)
      || !strncmp (arg, "yes", length))
    return 1;
  else
    if (!strncmp (arg, "off", length)
        || !strncmp (arg, "0", length)
        || !strncmp (arg, "no", length))
      return 0;
    else 
      {
        error ("\"on\" or \"off\" expected.");
        return 0;
      }
}

/* Do a "set" or "show" command.  ARG is NULL if no argument, or the text
   of the argument, and FROM_TTY is nonzero if this command is being entered
   directly by the user (i.e. these are just like any other
   command).  C is the command list element for the command.  */
void
do_setshow_command (arg, from_tty, c)
     char *arg;
     int from_tty;
     struct cmd_list_element *c;
{
  if (c->type == set_cmd)
    {
      switch (c->var_type)
        {
        case var_string:
          {
            char *new;
            char *p;
            char *q;
            int ch;
            
            if (arg == NULL)
              arg = "";
            new = (char *) xmalloc (strlen (arg) + 2);
            p = arg; q = new;
            while (ch = *p++)
              {
                if (ch == '\\')
                  {
                    /* \ at end of argument is used after spaces
                       so they won't be lost.  */
                    if (*p == 0)
                      break;
                    ch = parse_escape (&p);
                    if (ch == 0)
                      break; /* C loses */
                    else if (ch > 0)
                      *q++ = ch;
                  }
                else
                  *q++ = ch;
              }
            if (*(p - 1) != '\\')
              *q++ = ' ';
            *q++ = '\0';
            new = (char *) xrealloc (new, q - new);
            if (*(char **)c->var != NULL)
              free (*(char **)c->var);
            *(char **) c->var = new;
          }
          break;
        case var_string_noescape:
          if (arg == NULL)
            arg = "";
          if (*(char **)c->var != NULL)
            free (*(char **)c->var);
          *(char **) c->var = savestring (arg, strlen (arg));
          break;
        case var_filename:
          if (arg == NULL)
            error_no_arg ("filename to set it to.");
          if (*(char **)c->var != NULL)
            free (*(char **)c->var);
          *(char **)c->var = tilde_expand (arg);
          break;
        case var_boolean:
          *(int *) c->var = parse_binary_operation (arg);
          break;
        case var_uinteger:
          if (arg == NULL)
            error_no_arg ("integer to set it to.");
          *(int *) c->var = parse_and_eval_address (arg);
          if (*(int *) c->var == 0)
            *(int *) c->var = UINT_MAX;
          break;
        case var_zinteger:
          if (arg == NULL)
            error_no_arg ("integer to set it to.");
          *(int *) c->var = parse_and_eval_address (arg);
          break;
        default:
          error ("gdb internal error: bad var_type in do_setshow_command");
        }
    }
  else if (c->type == show_cmd)
    {
      /* Print doc minus "show" at start.  */
      print_doc_line (stdout, c->doc + 5);
      
      fputs_filtered (" is ", stdout);
      wrap_here ("    ");
      switch (c->var_type)
        {
      case var_string:
        {
          unsigned char *p;
          fputs_filtered ("\"", stdout);
          for (p = *(unsigned char **) c->var; *p != '\0'; p++)
            printchar (*p, stdout, '"');
          fputs_filtered ("\"", stdout);
        }
        break;
      case var_string_noescape:
      case var_filename:
        fputs_filtered ("\"", stdout);
        fputs_filtered (*(char **) c->var, stdout);
        fputs_filtered ("\"", stdout);
        break;
      case var_boolean:
        fputs_filtered (*(int *) c->var ? "on" : "off", stdout);
        break;
      case var_uinteger:
        if (*(unsigned int *) c->var == UINT_MAX) {
          fputs_filtered ("unlimited", stdout);
          break;
        }
        /* else fall through */
      case var_zinteger:
        fprintf_filtered (stdout, "%d", *(unsigned int *) c->var);
        break;
      default:
        error ("gdb internal error: bad var_type in do_setshow_command");
      }
      fputs_filtered (".\n", stdout);
    }
  else
    error ("gdb internal error: bad cmd_type in do_setshow_command");
  (*c->function) (NULL, from_tty, c);
}

/* Show all the settings in a list of show commands.  */

void
cmd_show_list (list, from_tty, prefix)
     struct cmd_list_element *list;
     int from_tty;
     char *prefix;
{
  for (; list != NULL; list = list->next) {
    /* If we find a prefix, run its list, prefixing our output by its
       prefix (with "show " skipped).  */
    if (list->prefixlist && !list->abbrev_flag)
      cmd_show_list (*list->prefixlist, from_tty, list->prefixname + 5);
    if (list->type == show_cmd)
      {
        fputs_filtered (prefix, stdout);
        fputs_filtered (list->name, stdout);
        fputs_filtered (":  ", stdout);
        do_setshow_command ((char *)NULL, from_tty, list);
      }
  }
}

static void
shell_escape (arg, from_tty)
     char *arg;
     int from_tty;
{
  int rc, status, pid;
  char *p, *user_shell;
  extern char *rindex ();

  if ((user_shell = (char *) getenv ("SHELL")) == NULL)
    user_shell = "/bin/sh";

  /* Get the name of the shell for arg0 */
  if ((p = rindex (user_shell, '/')) == NULL)
    p = user_shell;
  else
    p++;                        /* Get past '/' */

  if ((pid = fork()) == 0)
    {
      if (!arg)
        execl (user_shell, p, 0);
      else
        execl (user_shell, p, "-c", arg, 0);

      fprintf (stderr, "Exec of shell failed\n");
      exit (0);
    }

  if (pid != -1)
    while ((rc = wait (&status)) != pid && rc != -1)
      ;
  else
    error ("Fork failed");
}

static void
make_command (arg, from_tty)
     char *arg;
     int from_tty;
{
  char *p;

  if (arg == 0)
    p = "make";
  else
    {
      p = xmalloc (sizeof("make ") + strlen(arg));
      strcpy (p, "make ");
      strcpy (p + sizeof("make ")-1, arg);
    }
  
  shell_escape (p, from_tty);
}

static void
user_info_1 (c, stream)
     struct cmd_list_element *c;
     FILE *stream;
{
  register struct command_line *cmdlines;

  cmdlines = c->user_commands;
  if (!cmdlines)
    return;
  fprintf_filtered (stream, "User command %s:\n", c->name);
  while (cmdlines)
    {
      fprintf_filtered (stream, "%s\n", cmdlines->line); 
      cmdlines = cmdlines->next;
    }
  fputs_filtered ("\n", stream);
}

/* ARGSUSED */
static void
user_info (args, from_tty)
     char *args;
     int from_tty;
{
  struct cmd_list_element *c;
  extern struct cmd_list_element *cmdlist;

  if (args)
    {
      c = lookup_cmd (&args, cmdlist, "", 0, 1);
      if (c->class != class_user)
        error ("Not a user command.");
      user_info_1 (c, stdout);
    }
  else
    {
      for (c = cmdlist; c; c = c->next)
        {
          if (c->class == class_user)
            user_info_1 (c, stdout);
        }
    }
}

void
_initialize_command ()
{
  add_com ("shell", class_support, shell_escape,
           "Execute the rest of the line as a shell command.  \n\
With no arguments, run an inferior shell.");

  add_com ("make", class_support, make_command,
           "Run the ``make'' program using the rest of the line as arguments.");

  add_info ("user", user_info, "Show definitions of user defined commands.\n\
Argument is the name of the user defined command.\n\
With no argument, show definitions of all user defined commands.");
}