[deliverable/binutils-gdb.git] / gdb / cli / cli-script.c

/* GDB CLI command scripting.
   Copyright 1986-2000 Free Software Foundation, Inc.

   This file is part of GDB.

   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 2 of the License, 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., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include "defs.h"
#include "value.h"
#include "language.h"		/* For value_true */
#include <ctype.h>

#ifdef UI_OUT
#include "ui-out.h"
#endif

#include "top.h"
#include "cli/cli-cmds.h"
#include "cli/cli-decode.h"
#include "cli/cli-script.h"

/* From gdb/top.c */

extern void dont_repeat (void);

extern void do_restore_instream_cleanup (void *stream);

/* Prototypes for local functions */

static struct cleanup *
	make_cleanup_free_command_lines (struct command_line **arg);

static enum command_control_type
	recurse_read_control_structure (struct command_line *current_cmd);

static char *insert_args (char *line);

static struct cleanup * setup_user_args (char *p);

static void validate_comname (char *);

/* Level of control structure.  */
static int control_level;

/* Source command state variable. */
static int source_error_allocated;

/* Structure for arguments to user defined functions.  */
#define MAXUSERARGS 10
struct user_args
  {
    struct user_args *next;
    struct
      {
	char *arg;
	int len;
      }
    a[MAXUSERARGS];
    int count;
  }
 *user_args;

\f
/* Allocate, initialize a new command line structure for one of the
   control commands (if/while).  */

static struct command_line *
build_command_line (enum command_control_type type, char *args)
{
  struct command_line *cmd;

  if (args == NULL)
    error ("if/while commands require arguments.\n");

  cmd = (struct command_line *) xmalloc (sizeof (struct command_line));
  cmd->next = NULL;
  cmd->control_type = type;

  cmd->body_count = 1;
  cmd->body_list
    = (struct command_line **) xmalloc (sizeof (struct command_line *)
					* cmd->body_count);
  memset (cmd->body_list, 0, sizeof (struct command_line *) * cmd->body_count);
  cmd->line = savestring (args, strlen (args));
  return cmd;
}

/* Build and return a new command structure for the control commands
   such as "if" and "while".  */

static struct command_line *
get_command_line (enum command_control_type type, char *arg)
{
  struct command_line *cmd;
  struct cleanup *old_chain = NULL;

  /* Allocate and build a new command line structure.  */
  cmd = build_command_line (type, arg);

  old_chain = make_cleanup_free_command_lines (&cmd);

  /* Read in the body of this command.  */
  if (recurse_read_control_structure (cmd) == invalid_control)
    {
      warning ("error reading in control structure\n");
      do_cleanups (old_chain);
      return NULL;
    }

  discard_cleanups (old_chain);
  return cmd;
}

/* Recursively print a command (including full control structures).  */
#ifdef UI_OUT
void
print_command_lines (struct ui_out *uiout, struct command_line *cmd,
		     unsigned int depth)
{
  struct command_line *list;

  list = cmd;
  while (list)
    {

      if (depth)
	ui_out_spaces (uiout, 2 * depth);

      /* A simple command, print it and continue.  */
      if (list->control_type == simple_control)
	{
	  ui_out_field_string (uiout, NULL, list->line);
	  ui_out_text (uiout, "\n");
	  list = list->next;
	  continue;
	}

      /* loop_continue to jump to the start of a while loop, print it
         and continue. */
      if (list->control_type == continue_control)
	{
	  ui_out_field_string (uiout, NULL, "loop_continue");
	  ui_out_text (uiout, "\n");
	  list = list->next;
	  continue;
	}

      /* loop_break to break out of a while loop, print it and continue.  */
      if (list->control_type == break_control)
	{
	  ui_out_field_string (uiout, NULL, "loop_break");
	  ui_out_text (uiout, "\n");
	  list = list->next;
	  continue;
	}

      /* A while command.  Recursively print its subcommands and continue.  */
      if (list->control_type == while_control)
	{
	  ui_out_text (uiout, "while ");
	  ui_out_field_fmt (uiout, NULL, "while %s", list->line);
	  ui_out_text (uiout, "\n");
	  print_command_lines (uiout, *list->body_list, depth + 1);
	  ui_out_field_string (uiout, NULL, "end");
	  if (depth)
	    ui_out_spaces (uiout, 2 * depth);
	  ui_out_text (uiout, "end\n");
	  list = list->next;
	  continue;
	}

      /* An if command.  Recursively print both arms before continueing.  */
      if (list->control_type == if_control)
	{
	  ui_out_text (uiout, "if ");
	  ui_out_field_fmt (uiout, NULL, "if %s", list->line);
	  ui_out_text (uiout, "\n");
	  /* The true arm. */
	  print_command_lines (uiout, list->body_list[0], depth + 1);

	  /* Show the false arm if it exists.  */
	  if (list->body_count == 2)
	    {
	      if (depth)
		ui_out_spaces (uiout, 2 * depth);
	      ui_out_field_string (uiout, NULL, "else");
	      ui_out_text (uiout, "else\n");
	      print_command_lines (uiout, list->body_list[1], depth + 1);
	    }

	  ui_out_field_string (uiout, NULL, "end");
	  if (depth)
	    ui_out_spaces (uiout, 2 * depth);
	  ui_out_text (uiout, "end\n");
	  list = list->next;
	  continue;
	}

      /* ignore illegal command type and try next */
      list = list->next;
    }				/* while (list) */
}
#else
void
print_command_line (struct command_line *cmd, unsigned int depth,
		    struct ui_file *stream)
{
  unsigned int i;

  if (depth)
    {
      for (i = 0; i < depth; i++)
	fputs_filtered ("  ", stream);
    }

  /* A simple command, print it and return.  */
  if (cmd->control_type == simple_control)
    {
      fputs_filtered (cmd->line, stream);
      fputs_filtered ("\n", stream);
      return;
    }

  /* loop_continue to jump to the start of a while loop, print it
     and return. */
  if (cmd->control_type == continue_control)
    {
      fputs_filtered ("loop_continue\n", stream);
      return;
    }

  /* loop_break to break out of a while loop, print it and return.  */
  if (cmd->control_type == break_control)
    {
      fputs_filtered ("loop_break\n", stream);
      return;
    }

  /* A while command.  Recursively print its subcommands before returning.  */
  if (cmd->control_type == while_control)
    {
      struct command_line *list;
      fputs_filtered ("while ", stream);
      fputs_filtered (cmd->line, stream);
      fputs_filtered ("\n", stream);
      list = *cmd->body_list;
      while (list)
	{
	  print_command_line (list, depth + 1, stream);
	  list = list->next;
	}
    }

  /* An if command.  Recursively print both arms before returning.  */
  if (cmd->control_type == if_control)
    {
      fputs_filtered ("if ", stream);
      fputs_filtered (cmd->line, stream);
      fputs_filtered ("\n", stream);
      /* The true arm. */
      print_command_line (cmd->body_list[0], depth + 1, stream);

      /* Show the false arm if it exists.  */
      if (cmd->body_count == 2)
	{
	  if (depth)
	    {
	      for (i = 0; i < depth; i++)
		fputs_filtered ("  ", stream);
	    }
	  fputs_filtered ("else\n", stream);
	  print_command_line (cmd->body_list[1], depth + 1, stream);
	}
      if (depth)
	{
	  for (i = 0; i < depth; i++)
	    fputs_filtered ("  ", stream);
	}
      fputs_filtered ("end\n", stream);
    }
}
#endif

/* Execute the command in CMD.  */

void
execute_user_command (struct cmd_list_element *c, char *args)
{
  register struct command_line *cmdlines;
  struct cleanup *old_chain;
  enum command_control_type ret;

  old_chain = setup_user_args (args);

  cmdlines = c->user_commands;
  if (cmdlines == 0)
    /* Null command */
    return;

  /* Set the instream to 0, indicating execution of a
     user-defined function.  */
  old_chain = make_cleanup (do_restore_instream_cleanup, instream);
  instream = (FILE *) 0;
  while (cmdlines)
    {
      ret = execute_control_command (cmdlines);
      if (ret != simple_control && ret != break_control)
	{
	  warning ("Error in control structure.\n");
	  break;
	}
      cmdlines = cmdlines->next;
    }
  do_cleanups (old_chain);
}

enum command_control_type
execute_control_command (struct command_line *cmd)
{
  struct expression *expr;
  struct command_line *current;
  struct cleanup *old_chain = 0;
  value_ptr val;
  value_ptr val_mark;
  int loop;
  enum command_control_type ret;
  char *new_line;

  switch (cmd->control_type)
    {
    case simple_control:
      /* A simple command, execute it and return.  */
      new_line = insert_args (cmd->line);
      if (!new_line)
	return invalid_control;
      old_chain = make_cleanup (free_current_contents, &new_line);
      execute_command (new_line, 0);
      ret = cmd->control_type;
      break;

    case continue_control:
    case break_control:
      /* Return for "continue", and "break" so we can either
         continue the loop at the top, or break out.  */
      ret = cmd->control_type;
      break;

    case while_control:
      {
	/* Parse the loop control expression for the while statement.  */
	new_line = insert_args (cmd->line);
	if (!new_line)
	  return invalid_control;
	old_chain = make_cleanup (free_current_contents, &new_line);
	expr = parse_expression (new_line);
	make_cleanup (free_current_contents, &expr);

	ret = simple_control;
	loop = 1;

	/* Keep iterating so long as the expression is true.  */
	while (loop == 1)
	  {
	    int cond_result;

	    QUIT;

	    /* Evaluate the expression.  */
	    val_mark = value_mark ();
	    val = evaluate_expression (expr);
	    cond_result = value_true (val);
	    value_free_to_mark (val_mark);

	    /* If the value is false, then break out of the loop.  */
	    if (!cond_result)
	      break;

	    /* Execute the body of the while statement.  */
	    current = *cmd->body_list;
	    while (current)
	      {
		ret = execute_control_command (current);

		/* If we got an error, or a "break" command, then stop
		   looping.  */
		if (ret == invalid_control || ret == break_control)
		  {
		    loop = 0;
		    break;
		  }

		/* If we got a "continue" command, then restart the loop
		   at this point.  */
		if (ret == continue_control)
		  break;

		/* Get the next statement.  */
		current = current->next;
	      }
	  }

	/* Reset RET so that we don't recurse the break all the way down.  */
	if (ret == break_control)
	  ret = simple_control;

	break;
      }

    case if_control:
      {
	new_line = insert_args (cmd->line);
	if (!new_line)
	  return invalid_control;
	old_chain = make_cleanup (free_current_contents, &new_line);
	/* Parse the conditional for the if statement.  */
	expr = parse_expression (new_line);
	make_cleanup (free_current_contents, &expr);

	current = NULL;
	ret = simple_control;

	/* Evaluate the conditional.  */
	val_mark = value_mark ();
	val = evaluate_expression (expr);

	/* Choose which arm to take commands from based on the value of the
	   conditional expression.  */
	if (value_true (val))
	  current = *cmd->body_list;
	else if (cmd->body_count == 2)
	  current = *(cmd->body_list + 1);
	value_free_to_mark (val_mark);

	/* Execute commands in the given arm.  */
	while (current)
	  {
	    ret = execute_control_command (current);

	    /* If we got an error, get out.  */
	    if (ret != simple_control)
	      break;

	    /* Get the next statement in the body.  */
	    current = current->next;
	  }

	break;
      }

    default:
      warning ("Invalid control type in command structure.");
      return invalid_control;
    }

  if (old_chain)
    do_cleanups (old_chain);

  return ret;
}

/* "while" command support.  Executes a body of statements while the
   loop condition is nonzero.  */

void
while_command (char *arg, int from_tty)
{
  struct command_line *command = NULL;

  control_level = 1;
  command = get_command_line (while_control, arg);

  if (command == NULL)
    return;

  execute_control_command (command);
  free_command_lines (&command);
}

/* "if" command support.  Execute either the true or false arm depending
   on the value of the if conditional.  */

void
if_command (char *arg, int from_tty)
{
  struct command_line *command = NULL;

  control_level = 1;
  command = get_command_line (if_control, arg);

  if (command == NULL)
    return;

  execute_control_command (command);
  free_command_lines (&command);
}

/* Cleanup */
static void
arg_cleanup (void *ignore)
{
  struct user_args *oargs = user_args;
  if (!user_args)
    internal_error ("Internal error, arg_cleanup called with no user args.\n");

  user_args = user_args->next;
  free (oargs);
}

/* Bind the incomming arguments for a user defined command to
   $arg0, $arg1 ... $argMAXUSERARGS.  */

static struct cleanup *
setup_user_args (char *p)
{
  struct user_args *args;
  struct cleanup *old_chain;
  unsigned int arg_count = 0;

  args = (struct user_args *) xmalloc (sizeof (struct user_args));
  memset (args, 0, sizeof (struct user_args));

  args->next = user_args;
  user_args = args;

  old_chain = make_cleanup (arg_cleanup, 0/*ignored*/);

  if (p == NULL)
    return old_chain;

  while (*p)
    {
      char *start_arg;
      int squote = 0;
      int dquote = 0;
      int bsquote = 0;

      if (arg_count >= MAXUSERARGS)
	{
	  error ("user defined function may only have %d arguments.\n",
		 MAXUSERARGS);
	  return old_chain;
	}

      /* Strip whitespace.  */
      while (*p == ' ' || *p == '\t')
	p++;

      /* P now points to an argument.  */
      start_arg = p;
      user_args->a[arg_count].arg = p;

      /* Get to the end of this argument.  */
      while (*p)
	{
	  if (((*p == ' ' || *p == '\t')) && !squote && !dquote && !bsquote)
	    break;
	  else
	    {
	      if (bsquote)
		bsquote = 0;
	      else if (*p == '\\')
		bsquote = 1;
	      else if (squote)
		{
		  if (*p == '\'')
		    squote = 0;
		}
	      else if (dquote)
		{
		  if (*p == '"')
		    dquote = 0;
		}
	      else
		{
		  if (*p == '\'')
		    squote = 1;
		  else if (*p == '"')
		    dquote = 1;
		}
	      p++;
	    }
	}

      user_args->a[arg_count].len = p - start_arg;
      arg_count++;
      user_args->count++;
    }
  return old_chain;
}

/* Given character string P, return a point to the first argument ($arg),
   or NULL if P contains no arguments.  */

static char *
locate_arg (char *p)
{
  while ((p = strchr (p, '$')))
    {
      if (strncmp (p, "$arg", 4) == 0 && isdigit (p[4]))
	return p;
      p++;
    }
  return NULL;
}

/* Insert the user defined arguments stored in user_arg into the $arg
   arguments found in line, with the updated copy being placed into nline.  */

static char *
insert_args (char *line)
{
  char *p, *save_line, *new_line;
  unsigned len, i;

  /* First we need to know how much memory to allocate for the new line.  */
  save_line = line;
  len = 0;
  while ((p = locate_arg (line)))
    {
      len += p - line;
      i = p[4] - '0';

      if (i >= user_args->count)
	{
	  error ("Missing argument %d in user function.\n", i);
	  return NULL;
	}
      len += user_args->a[i].len;
      line = p + 5;
    }

  /* Don't forget the tail.  */
  len += strlen (line);

  /* Allocate space for the new line and fill it in.  */
  new_line = (char *) xmalloc (len + 1);
  if (new_line == NULL)
    return NULL;

  /* Restore pointer to beginning of old line.  */
  line = save_line;

  /* Save pointer to beginning of new line.  */
  save_line = new_line;

  while ((p = locate_arg (line)))
    {
      int i, len;

      memcpy (new_line, line, p - line);
      new_line += p - line;
      i = p[4] - '0';

      len = user_args->a[i].len;
      if (len)
	{
	  memcpy (new_line, user_args->a[i].arg, len);
	  new_line += len;
	}
      line = p + 5;
    }
  /* Don't forget the tail.  */
  strcpy (new_line, line);

  /* Return a pointer to the beginning of the new line.  */
  return save_line;
}

\f
/* Expand the body_list of COMMAND so that it can hold NEW_LENGTH
   code bodies.  This is typically used when we encounter an "else"
   clause for an "if" command.  */

static void
realloc_body_list (struct command_line *command, int new_length)
{
  int n;
  struct command_line **body_list;

  n = command->body_count;

  /* Nothing to do?  */
  if (new_length <= n)
    return;

  body_list = (struct command_line **)
    xmalloc (sizeof (struct command_line *) * new_length);

  memcpy (body_list, command->body_list, sizeof (struct command_line *) * n);

  free (command->body_list);
  command->body_list = body_list;
  command->body_count = new_length;
}

/* Read one line from the input stream.  If the command is an "else" or
   "end", return such an indication to the caller.  */

static enum misc_command_type
read_next_line (struct command_line **command)
{
  char *p, *p1, *prompt_ptr, control_prompt[256];
  int i = 0;

  if (control_level >= 254)
    error ("Control nesting too deep!\n");

  /* Set a prompt based on the nesting of the control commands.  */
  if (instream == stdin || (instream == 0 && readline_hook != NULL))
    {
      for (i = 0; i < control_level; i++)
	control_prompt[i] = ' ';
      control_prompt[i] = '>';
      control_prompt[i + 1] = '\0';
      prompt_ptr = (char *) &control_prompt[0];
    }
  else
    prompt_ptr = NULL;

  p = command_line_input (prompt_ptr, instream == stdin, "commands");

  /* Not sure what to do here.  */
  if (p == NULL)
    return end_command;

  /* Strip leading and trailing whitespace.  */
  while (*p == ' ' || *p == '\t')
    p++;

  p1 = p + strlen (p);
  while (p1 != p && (p1[-1] == ' ' || p1[-1] == '\t'))
    p1--;

  /* Blanks and comments don't really do anything, but we need to
     distinguish them from else, end and other commands which can be
     executed.  */
  if (p1 == p || p[0] == '#')
    return nop_command;

  /* Is this the end of a simple, while, or if control structure?  */
  if (p1 - p == 3 && !strncmp (p, "end", 3))
    return end_command;

  /* Is the else clause of an if control structure?  */
  if (p1 - p == 4 && !strncmp (p, "else", 4))
    return else_command;

  /* Check for while, if, break, continue, etc and build a new command
     line structure for them.  */
  if (p1 - p > 5 && !strncmp (p, "while", 5))
    *command = build_command_line (while_control, p + 6);
  else if (p1 - p > 2 && !strncmp (p, "if", 2))
    *command = build_command_line (if_control, p + 3);
  else if (p1 - p == 10 && !strncmp (p, "loop_break", 10))
    {
      *command = (struct command_line *)
	xmalloc (sizeof (struct command_line));
      (*command)->next = NULL;
      (*command)->line = NULL;
      (*command)->control_type = break_control;
      (*command)->body_count = 0;
      (*command)->body_list = NULL;
    }
  else if (p1 - p == 13 && !strncmp (p, "loop_continue", 13))
    {
      *command = (struct command_line *)
	xmalloc (sizeof (struct command_line));
      (*command)->next = NULL;
      (*command)->line = NULL;
      (*command)->control_type = continue_control;
      (*command)->body_count = 0;
      (*command)->body_list = NULL;
    }
  else
    {
      /* A normal command.  */
      *command = (struct command_line *)
	xmalloc (sizeof (struct command_line));
      (*command)->next = NULL;
      (*command)->line = savestring (p, p1 - p);
      (*command)->control_type = simple_control;
      (*command)->body_count = 0;
      (*command)->body_list = NULL;
    }

  /* Nothing special.  */
  return ok_command;
}

/* Recursively read in the control structures and create a command_line 
   structure from them.

   The parent_control parameter is the control structure in which the
   following commands are nested.  */

static enum command_control_type
recurse_read_control_structure (struct command_line *current_cmd)
{
  int current_body, i;
  enum misc_command_type val;
  enum command_control_type ret;
  struct command_line **body_ptr, *child_tail, *next;

  child_tail = NULL;
  current_body = 1;

  /* Sanity checks.  */
  if (current_cmd->control_type == simple_control)
    {
      error ("Recursed on a simple control type\n");
      return invalid_control;
    }

  if (current_body > current_cmd->body_count)
    {
      error ("Allocated body is smaller than this command type needs\n");
      return invalid_control;
    }

  /* Read lines from the input stream and build control structures.  */
  while (1)
    {
      dont_repeat ();

      next = NULL;
      val = read_next_line (&next);

      /* Just skip blanks and comments.  */
      if (val == nop_command)
	continue;

      if (val == end_command)
	{
	  if (current_cmd->control_type == while_control
	      || current_cmd->control_type == if_control)
	    {
	      /* Success reading an entire control structure.  */
	      ret = simple_control;
	      break;
	    }
	  else
	    {
	      ret = invalid_control;
	      break;
	    }
	}

      /* Not the end of a control structure.  */
      if (val == else_command)
	{
	  if (current_cmd->control_type == if_control
	      && current_body == 1)
	    {
	      realloc_body_list (current_cmd, 2);
	      current_body = 2;
	      child_tail = NULL;
	      continue;
	    }
	  else
	    {
	      ret = invalid_control;
	      break;
	    }
	}

      if (child_tail)
	{
	  child_tail->next = next;
	}
      else
	{
	  body_ptr = current_cmd->body_list;
	  for (i = 1; i < current_body; i++)
	    body_ptr++;

	  *body_ptr = next;

	}

      child_tail = next;

      /* If the latest line is another control structure, then recurse
         on it.  */
      if (next->control_type == while_control
	  || next->control_type == if_control)
	{
	  control_level++;
	  ret = recurse_read_control_structure (next);
	  control_level--;

	  if (ret != simple_control)
	    break;
	}
    }

  dont_repeat ();

  return ret;
}

/* Read lines from the input stream and accumulate them in a chain of
   struct command_line's, which is then returned.  For input from a
   terminal, the special command "end" is used to mark the end of the
   input, and is not included in the returned chain of commands. */

#define END_MESSAGE "End with a line saying just \"end\"."

struct command_line *
read_command_lines (char *prompt_arg, int from_tty)
{
  struct command_line *head, *tail, *next;
  struct cleanup *old_chain;
  enum command_control_type ret;
  enum misc_command_type val;

  control_level = 0;
  if (readline_begin_hook)
    {
      /* Note - intentional to merge messages with no newline */
      (*readline_begin_hook) ("%s  %s\n", prompt_arg, END_MESSAGE);
    }
  else if (from_tty && input_from_terminal_p ())
    {
      printf_unfiltered ("%s\n%s\n", prompt_arg, END_MESSAGE);
      gdb_flush (gdb_stdout);
    }

  head = tail = NULL;
  old_chain = NULL;

  while (1)
    {
      val = read_next_line (&next);

      /* Ignore blank lines or comments.  */
      if (val == nop_command)
	continue;

      if (val == end_command)
	{
	  ret = simple_control;
	  break;
	}

      if (val != ok_command)
	{
	  ret = invalid_control;
	  break;
	}

      if (next->control_type == while_control
	  || next->control_type == if_control)
	{
	  control_level++;
	  ret = recurse_read_control_structure (next);
	  control_level--;

	  if (ret == invalid_control)
	    break;
	}

      if (tail)
	{
	  tail->next = next;
	}
      else
	{
	  head = next;
	  old_chain = make_cleanup_free_command_lines (&head);
	}
      tail = next;
    }

  dont_repeat ();

  if (head)
    {
      if (ret != invalid_control)
	{
	  discard_cleanups (old_chain);
	}
      else
	do_cleanups (old_chain);
    }

  if (readline_end_hook)
    {
      (*readline_end_hook) ();
    }
  return (head);
}

/* Free a chain of struct command_line's.  */

void
free_command_lines (struct command_line **lptr)
{
  register struct command_line *l = *lptr;
  register struct command_line *next;
  struct command_line **blist;
  int i;

  while (l)
    {
      if (l->body_count > 0)
	{
	  blist = l->body_list;
	  for (i = 0; i < l->body_count; i++, blist++)
	    free_command_lines (blist);
	}
      next = l->next;
      free (l->line);
      free ((PTR) l);
      l = next;
    }
}

static void
do_free_command_lines_cleanup (void *arg)
{
  free_command_lines (arg);
}

static struct cleanup *
make_cleanup_free_command_lines (struct command_line **arg)
{
  return make_cleanup (do_free_command_lines_cleanup, arg);
}
\f
static void
validate_comname (char *comname)
{
  register char *p;

  if (comname == 0)
    error_no_arg ("name of command to define");

  p = comname;
  while (*p)
    {
      if (!isalnum (*p) && *p != '-' && *p != '_')
	error ("Junk in argument list: \"%s\"", p);
      p++;
    }
}

/* This is just a placeholder in the command data structures.  */
static void
user_defined_command (char *ignore, int from_tty)
{
}

void
define_command (char *comname, int from_tty)
{
#define MAX_TMPBUF 128   
  enum cmd_hook_type
    {
      CMD_NO_HOOK = 0,
      CMD_PRE_HOOK,
      CMD_POST_HOOK
    };
  register struct command_line *cmds;
  register struct cmd_list_element *c, *newc, *oldc, *hookc = 0;
  char *tem = comname;
  char *tem2; 
  char tmpbuf[MAX_TMPBUF];
  int  hook_type      = CMD_NO_HOOK;
  int  hook_name_size = 0;
   
#define	HOOK_STRING	"hook-"
#define	HOOK_LEN 5
#define HOOK_POST_STRING "hookpost-"
#define HOOK_POST_LEN    9

  validate_comname (comname);

  /* Look it up, and verify that we got an exact match.  */
  c = lookup_cmd (&tem, cmdlist, "", -1, 1);
  if (c && !STREQ (comname, c->name))
    c = 0;

  if (c)
    {
      if (c->class == class_user || c->class == class_alias)
	tem = "Redefine command \"%s\"? ";
      else
	tem = "Really redefine built-in command \"%s\"? ";
      if (!query (tem, c->name))
	error ("Command \"%s\" not redefined.", c->name);
    }

  /* If this new command is a hook, then mark the command which it
     is hooking.  Note that we allow hooking `help' commands, so that
     we can hook the `stop' pseudo-command.  */

  if (!strncmp (comname, HOOK_STRING, HOOK_LEN))
    {
       hook_type      = CMD_PRE_HOOK;
       hook_name_size = HOOK_LEN;
    }
  else if (!strncmp (comname, HOOK_POST_STRING, HOOK_POST_LEN))
    {
      hook_type      = CMD_POST_HOOK;
      hook_name_size = HOOK_POST_LEN;
    }
   
  if (hook_type != CMD_NO_HOOK)
    {
      /* Look up cmd it hooks, and verify that we got an exact match.  */
      tem = comname + hook_name_size;
      hookc = lookup_cmd (&tem, cmdlist, "", -1, 0);
      if (hookc && !STREQ (comname + hook_name_size, hookc->name))
	hookc = 0;
      if (!hookc)
	{
	  warning ("Your new `%s' command does not hook any existing command.",
		   comname);
	  if (!query ("Proceed? "))
	    error ("Not confirmed.");
	}
    }

  comname = savestring (comname, strlen (comname));

  /* If the rest of the commands will be case insensitive, this one
     should behave in the same manner. */
  for (tem = comname; *tem; tem++)
    if (isupper (*tem))
      *tem = tolower (*tem);

  sprintf (tmpbuf, "Type commands for definition of \"%s\".", comname);
  cmds = read_command_lines (tmpbuf, from_tty);

  if (c && c->class == class_user)
    free_command_lines (&c->user_commands);

  newc = add_cmd (comname, class_user, user_defined_command,
		  (c && c->class == class_user)
		  ? c->doc : savestring ("User-defined.", 13), &cmdlist);
  newc->user_commands = cmds;

  /* If this new command is a hook, then mark both commands as being
     tied.  */
  if (hookc)
    {
      switch (hook_type)
        {
        case CMD_PRE_HOOK:
          hookc->hook_pre  = newc;  /* Target gets hooked.  */
          newc->hookee_pre = hookc; /* We are marked as hooking target cmd. */
          break;
        case CMD_POST_HOOK:
          hookc->hook_pre  = newc;  /* Target gets hooked.  */
          newc->hookee_pre = hookc; /* We are marked as hooking target cmd. */
          break;
        default:
          /* Should never come here as hookc would be 0. */
        }
    }
}

void
document_command (char *comname, int from_tty)
{
  struct command_line *doclines;
  register struct cmd_list_element *c;
  char *tem = comname;
  char tmpbuf[128];

  validate_comname (comname);

  c = lookup_cmd (&tem, cmdlist, "", 0, 1);

  if (c->class != class_user)
    error ("Command \"%s\" is built-in.", comname);

  sprintf (tmpbuf, "Type documentation for \"%s\".", comname);
  doclines = read_command_lines (tmpbuf, from_tty);

  if (c->doc)
    free (c->doc);

  {
    register struct command_line *cl1;
    register int len = 0;

    for (cl1 = doclines; cl1; cl1 = cl1->next)
      len += strlen (cl1->line) + 1;

    c->doc = (char *) xmalloc (len + 1);
    *c->doc = 0;

    for (cl1 = doclines; cl1; cl1 = cl1->next)
      {
	strcat (c->doc, cl1->line);
	if (cl1->next)
	  strcat (c->doc, "\n");
      }
  }

  free_command_lines (&doclines);
}
\f
struct source_cleanup_lines_args
{
  int old_line;
  char *old_file;
  char *old_pre_error;
  char *old_error_pre_print;
};

static void
source_cleanup_lines (PTR args)
{
  struct source_cleanup_lines_args *p =
  (struct source_cleanup_lines_args *) args;
  source_line_number = p->old_line;
  source_file_name = p->old_file;
  source_pre_error = p->old_pre_error;
  error_pre_print = p->old_error_pre_print;
}

/* ARGSUSED */
static void
do_fclose_cleanup (void *stream)
{
  fclose (stream);
}

/* Used to implement source_command */

void
script_from_file (FILE *stream, char *file)
{
  struct cleanup *old_cleanups;
  struct source_cleanup_lines_args old_lines;
  int needed_length;

  if (stream == NULL)
    {
      internal_error ("called with NULL file pointer!");
    }

  old_cleanups = make_cleanup (do_fclose_cleanup, stream);

  old_lines.old_line = source_line_number;
  old_lines.old_file = source_file_name;
  old_lines.old_pre_error = source_pre_error;
  old_lines.old_error_pre_print = error_pre_print;
  make_cleanup (source_cleanup_lines, &old_lines);
  source_line_number = 0;
  source_file_name = file;
  source_pre_error = error_pre_print == NULL ? "" : error_pre_print;
  source_pre_error = savestring (source_pre_error, strlen (source_pre_error));
  make_cleanup (free, source_pre_error);
  /* This will get set every time we read a line.  So it won't stay "" for
     long.  */
  error_pre_print = "";

  needed_length = strlen (source_file_name) + strlen (source_pre_error) + 80;
  if (source_error_allocated < needed_length)
    {
      source_error_allocated *= 2;
      if (source_error_allocated < needed_length)
	source_error_allocated = needed_length;
      if (source_error == NULL)
	source_error = xmalloc (source_error_allocated);
      else
	source_error = xrealloc (source_error, source_error_allocated);
    }

  read_command_file (stream);

  do_cleanups (old_cleanups);
}

void
show_user_1 (struct cmd_list_element *c, struct ui_file *stream)
{
  register struct command_line *cmdlines;

  cmdlines = c->user_commands;
  if (!cmdlines)
    return;
  fputs_filtered ("User command ", stream);
  fputs_filtered (c->name, stream);
  fputs_filtered (":\n", stream);

#ifdef UI_OUT
  print_command_lines (uiout, cmdlines, 1);
  fputs_filtered ("\n", stream);
#else
  while (cmdlines)
    {
      print_command_line (cmdlines, 4, stream);
      cmdlines = cmdlines->next;
    }
  fputs_filtered ("\n", stream);
#endif
}