lread.c

早期freebsd实现

/* Lisp parsing and input streams.
   Copyright (C) 1985, 1986, 1987 Free Software Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs 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.

GNU Emacs 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 GNU Emacs; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */


#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/file.h>
#undef NULL
#include "config.h"
#include "lisp.h"

#ifndef standalone
#include "buffer.h"
#include "paths.h"
#endif

#ifdef lint
#include <sys/inode.h>
#endif /* lint */

#ifndef X_OK
#define X_OK 01
#endif

Lisp_Object Qread_char, Qget_file_char, Qstandard_input;
Lisp_Object Qvariable_documentation, Vvalues, Vstandard_input;

/* non-zero if inside `load' */
int load_in_progress;

/* Search path for files to be loaded. */
Lisp_Object Vload_path;

/* File for get_file_char to read from.  Use by load */
static FILE *instream;

/* When nonzero, read conses in pure space */
static int read_pure;

/* For use within read-from-string (this reader is non-reentrant!!) */
static int read_from_string_index;
static int read_from_string_limit;

/* Handle unreading and rereading of characters.
 Write READCHAR to read a character, UNREAD(c) to unread c to be read again. */

static int unrch;

static int readchar (readcharfun)
     Lisp_Object readcharfun;
{
  Lisp_Object tem;
  register struct buffer *inbuffer;
  register int c, mpos;

  if (unrch >= 0)
    {
      c = unrch;
      unrch = -1;
      return c;
    }
  if (XTYPE (readcharfun) == Lisp_Buffer)
    {
      inbuffer = XBUFFER (readcharfun);

      if (BUF_PT (inbuffer) >= BUF_ZV (inbuffer))
	return -1;
      c = *(unsigned char *) BUF_CHAR_ADDRESS (inbuffer, BUF_PT (inbuffer));
      SET_BUF_PT (inbuffer, BUF_PT (inbuffer) + 1);
      return c;
    }
  if (XTYPE (readcharfun) == Lisp_Marker)
    {
      inbuffer = XMARKER (readcharfun)->buffer;
      mpos = marker_position (readcharfun);

      if (mpos > BUF_ZV (inbuffer) - 1)
	return -1;
      c = *(unsigned char *) BUF_CHAR_ADDRESS (inbuffer, mpos);
      if (mpos != BUF_GPT (inbuffer))
	XMARKER (readcharfun)->bufpos++;
      else
	Fset_marker (readcharfun, make_number (mpos + 1),
		     Fmarker_buffer (readcharfun));
      return c;
    }
  if (EQ (readcharfun, Qget_file_char))
    return getc (instream);

  if (XTYPE (readcharfun) == Lisp_String)
    {
      register int c;
      /* This used to be return of a conditional expression,
	 but that truncated -1 to a char on VMS.  */
      if (read_from_string_index < read_from_string_limit)
	c = XSTRING (readcharfun)->data[read_from_string_index++];
      else
	c = -1;
      return c;
    }

  tem = call0 (readcharfun);

  if (NULL (tem))
    return -1;
  return XINT (tem);
}

#define READCHAR readchar(readcharfun)
#define UNREAD(c) (unrch = c)

static Lisp_Object read0 (), read1 (), read_list (), read_vector ();

/* get a character from the tty */

DEFUN ("read-char", Fread_char, Sread_char, 0, 0, 0,
  "Read a character from the command input (keyboard or macro).\n\
It is returned as a number.")
  ()
{
  register Lisp_Object val;

#ifndef standalone
  XSET (val, Lisp_Int, read_command_char (0));
#else
  XSET (val, Lisp_Int, getchar ());
#endif

  return val;
}

DEFUN ("get-file-char", Fget_file_char, Sget_file_char, 0, 0, 0,
  "Don't use this yourself.")
  ()
{
  register Lisp_Object val;
  XSET (val, Lisp_Int, getc (instream));
  return val;
}

void readevalloop ();
static Lisp_Object load_unwind ();

DEFUN ("load", Fload, Sload, 1, 4, 0,
  "Execute a file of Lisp code named FILE.\n\
First tries FILE with .elc appended, then tries with .el,\n\
 then tries FILE unmodified.  Searches directories in  load-path.\n\
If optional second arg NOERROR is non-nil,\n\
 report no error if FILE doesn't exist.\n\
Print messages at start and end of loading unless\n\
 optional third arg NOMESSAGE is non-nil.\n\
If optional fourth arg NOSUFFIX is non-nil, don't try adding\n\
 suffixes .elc or .el to the specified name FILE.\n\
Return t if file exists.")
  (str, noerror, nomessage, nosuffix)
     Lisp_Object str, noerror, nomessage, nosuffix;
{
  register FILE *stream;
  register int fd = -1;
  register Lisp_Object lispstream;
  register FILE **ptr;
  int count = specpdl_ptr - specpdl;
  struct gcpro gcpro1;

  CHECK_STRING (str, 0);
  str = Fsubstitute_in_file_name (str);

  /* Avoid weird lossage with null string as arg,
     since it would try to load a directory as a Lisp file */
  if (XSTRING (str)->size > 0)
    {
      fd = openp (Vload_path, str, !NULL (nosuffix) ? "" : ".elc:.el:", 0, 0);
    }

  if (fd < 0)
    if (NULL (noerror))
      while (1)
	Fsignal (Qfile_error, Fcons (build_string ("Cannot open load file"),
				     Fcons (str, Qnil)));
    else return Qnil;

  stream = fdopen (fd, "r");
  if (stream == 0)
    {
      close (fd);
      error ("Failure to create stdio stream for %s", XSTRING (str)->data);
    }

  if (NULL (nomessage))
    message ("Loading %s...", XSTRING (str)->data);

  GCPRO1 (str);
  ptr = (FILE **) xmalloc (sizeof (FILE *));
  *ptr = stream;
  XSET (lispstream, Lisp_Internal_Stream, (int) ptr);
  record_unwind_protect (load_unwind, lispstream);
  load_in_progress++;
  readevalloop (Qget_file_char, stream, Feval, 0);
  unbind_to (count);
  UNGCPRO;

  if (!noninteractive && NULL (nomessage))
    message ("Loading %s...done", XSTRING (str)->data);
  return Qt;
}

static Lisp_Object
load_unwind (stream)  /* used as unwind-protect function in load */
     Lisp_Object stream;
{
  fclose (*(FILE **) XSTRING (stream));
  free (XPNTR (stream));
  if (--load_in_progress < 0) load_in_progress = 0;
  return Qnil;
}


static int
absolute_filename_p (pathname)
     Lisp_Object pathname;
{
  register unsigned char *s = XSTRING (pathname)->data;
  return (*s == '~' || *s == '/'
#ifdef VMS
	  || index (s, ':')
#endif /* VMS */
	  );
}

/* Search for a file whose name is STR, looking in directories
   in the Lisp list PATH, and trying suffixes from SUFFIX.
   SUFFIX is a string containing possible suffixes separated by colons.
   On success, returns a file descriptor.  On failure, returns -1.

   EXEC_ONLY nonzero means don't open the files,
   just look for one that is executable.  In this case,
   returns 1 on success.

   If STOREPTR is nonzero, it points to a slot where the name of
   the file actually found should be stored as a Lisp string.
   Nil is stored there on failure.  */

int
openp (path, str, suffix, storeptr, exec_only)
     Lisp_Object path, str;
     char *suffix;
     Lisp_Object *storeptr;
     int exec_only;
{
  register int fd;
  int fn_size = 100;
  char buf[100];
  register char *fn = buf;
  int absolute = 0;
  int want_size;
  register Lisp_Object filename;
  struct stat st;

  if (storeptr)
    *storeptr = Qnil;

  if (absolute_filename_p (str))
    absolute = 1;

  for (; !NULL (path); path = Fcdr (path))
    {
      char *nsuffix;

      filename = Fexpand_file_name (str, Fcar (path));
      if (!absolute_filename_p (filename))
	/* If there are non-absolute elts in PATH (eg ".") */
	/* Of course, this could conceivably lose if luser sets
	   default-directory to be something non-absolute... */
	{
	  filename = Fexpand_file_name (filename, current_buffer->directory);
	  if (!absolute_filename_p (filename))
	    /* Give up on this path element! */
	    continue;
	}

      /* Calculate maximum size of any filename made from
	 this path element/specified file name and any possible suffix.  */
      want_size = strlen (suffix) + XSTRING (filename)->size + 1;
      if (fn_size < want_size)
	fn = (char *) alloca (fn_size = 100 + want_size);

      nsuffix = suffix;

      /* Loop over suffixes.  */
      while (1)
	{
	  char *esuffix = (char *) index (nsuffix, ':');
	  int lsuffix = esuffix ? esuffix - nsuffix : strlen (nsuffix);

	  /* Concatenate path element/specified name with the suffix.  */
	  strncpy (fn, XSTRING (filename)->data, XSTRING (filename)->size);
	  fn[XSTRING (filename)->size] = 0;
	  if (lsuffix != 0)  /* Bug happens on CCI if lsuffix is 0.  */
	    strncat (fn, nsuffix, lsuffix);

	  /* Ignore file if it's a directory.  */
	  if (stat (fn, &st) >= 0
	      && (st.st_mode & S_IFMT) != S_IFDIR)
	    {
	      /* Check that we can access or open it.  */
	      if (exec_only)
		fd = !access (fn, X_OK) ? 1 : -1;
	      else
		fd = open (fn, 0, 0);

	      if (fd >= 0)
		{
		  /* We succeeded; return this descriptor and filename.  */
		  if (storeptr)
		    *storeptr = build_string (fn);
		  return fd;
		}
	    }

	  /* Advance to next suffix.  */
	  if (esuffix == 0)
	    break;
	  nsuffix += lsuffix + 1;
	}
      if (absolute) return -1;
    }

  return -1;
}


Lisp_Object
unreadpure ()	/* Used as unwind-protect function in readevalloop */
{
  read_pure = 0;
  return Qnil;
}

static void
readevalloop (readcharfun, stream, evalfun, printflag)
     Lisp_Object readcharfun;
     FILE *stream;     
     Lisp_Object (*evalfun) ();
     int printflag;
{
  register int c;
  register Lisp_Object val;
  register int xunrch;
  int count = specpdl_ptr - specpdl;

  specbind (Qstandard_input, readcharfun);

  unrch = -1;

  while (1)
    {
      instream = stream;
      c = READCHAR;
      if (c == ';')
	{
	  while ((c = READCHAR) != '\n' && c != -1);
	  continue;
	}
      if (c < 0) break;
      if (c == ' ' || c == '\t' || c == '\n' || c == '\f') continue;

      if (!NULL (Vpurify_flag) && c == '(')
	{
	  record_unwind_protect (unreadpure, Qnil);
	  val = read_list (-1, readcharfun);
	  unbind_to (count + 1);
	}
      else
	{
	  UNREAD (c);
	  val = read0 (readcharfun);
	}

      xunrch = unrch;
      unrch = -1;
      val = (*evalfun) (val);
      if (printflag)
	{
	  Vvalues = Fcons (val, Vvalues);
	  if (EQ (Vstandard_output, Qt))
	    Fprin1 (val, Qnil);
	  else
	    Fprint (val, Qnil);
	}
      unrch = xunrch;
    }

  unbind_to (count);
}

#ifndef standalone

DEFUN ("eval-current-buffer", Feval_current_buffer, Seval_current_buffer, 0, 1, "",
  "Execute the current buffer as Lisp code.\n\
Programs can pass argument PRINTFLAG which controls printing of output:\n\
nil means discard it; anything else is stream for print.")
  (printflag)
     Lisp_Object printflag;
{
  int count = specpdl_ptr - specpdl;
  Lisp_Object tem;
  if (NULL (printflag))
    tem = Qsymbolp;
  else
    tem = printflag;
  specbind (Qstandard_output, tem);
  record_unwind_protect (save_excursion_restore, save_excursion_save ());
  SET_PT (BEGV);
  readevalloop (Fcurrent_buffer (), 0, Feval, !NULL (printflag));
  unbind_to (count);
  return Qnil;
}