ftw.c

Newlib 嵌入式 C库 标准实现代码

/* File tree walker functions.
   Copyright (C) 1996,1997,1998,1999,2000,2001 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <[e-mail]>, 1996.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

/* Modified for newlib by Jeff Johnston, July 26, 2002 */

#define _GNU_SOURCE 1

#include <dirent.h>
#include <errno.h>
#include <ftw.h>
#include <search.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/param.h>
#include <sys/stat.h>

extern struct dirent64 *__readdir64 (DIR *);

/* #define NDEBUG 1 */
#include <assert.h>

/* Support for the LFS API version.  */
#ifndef FTW_NAME
# define FTW_NAME ftw
# define NFTW_NAME nftw
# define INO_T ino_t
# define STAT stat
# define LXSTAT lstat
# define XSTAT stat
# define FTW_FUNC_T __ftw_func_t
# define NFTW_FUNC_T __nftw_func_t
#endif

#define dirfd(x) ((x)->dd_fd)

struct dir_data
{
  DIR *stream;
  char *content;
};

struct known_object
{
  dev_t dev;
  INO_T ino;
};

struct ftw_data
{
  /* Array with pointers to open directory streams.  */
  struct dir_data **dirstreams;
  size_t actdir;
  size_t maxdir;

  /* Buffer containing name of currently processed object.  */
  char *dirbuf;
  size_t dirbufsize;

  /* Passed as fourth argument to `nftw' callback.  The `base' member
     tracks the content of the `dirbuf'.  */
  struct FTW ftw;

  /* Flags passed to `nftw' function.  0 for `ftw'.  */
  int flags;

  /* Conversion array for flag values.  It is the identity mapping for
     `nftw' calls, otherwise it maps the values to those know by
     `ftw'.  */
  const int *cvt_arr;

  /* Callback function.  We always use the `nftw' form.  */
  NFTW_FUNC_T func;

  /* Device of starting point.  Needed for FTW_MOUNT.  */
  dev_t dev;

  /* Data structure for keeping fingerprints of already processed
     object.  This is needed when not using FTW_PHYS.  */
  void *known_objects;
};


/* Internally we use the FTW_* constants used for `nftw'.  When the
   process called `ftw' we must reduce the flag to the known flags
   for `ftw'.  */
static const int nftw_arr[] =
{
  FTW_F, FTW_D, FTW_DNR, FTW_NS, FTW_SL, FTW_DP, FTW_SLN
};

static const int ftw_arr[] =
{
  FTW_F, FTW_D, FTW_DNR, FTW_NS, FTW_F, FTW_D, FTW_NS
};


/* Forward declarations of local functions.  */
static int ftw_dir (struct ftw_data *data, struct STAT *st);


static int
object_compare (const void *p1, const void *p2)
{
  /* We don't need a sophisticated and useful comparison.  We are only
     interested in equality.  However, we must be careful not to
     accidentally compare `holes' in the structure.  */
  const struct known_object *kp1 = p1, *kp2 = p2;
  int cmp1;
  cmp1 = (kp1->dev > kp2->dev) - (kp1->dev < kp2->dev);
  if (cmp1 != 0)
    return cmp1;
  return (kp1->ino > kp2->ino) - (kp1->ino < kp2->ino);
}


static inline int
add_object (struct ftw_data *data, struct STAT *st)
{
  struct known_object *newp = malloc (sizeof (struct known_object));
  if (newp == NULL)
    return -1;
  newp->dev = st->st_dev;
  newp->ino = st->st_ino;
  return tsearch (newp, &data->known_objects, object_compare) ? 0 : -1;
}


static inline int
find_object (struct ftw_data *data, struct STAT *st)
{
  struct known_object obj = { dev: st->st_dev, ino: st->st_ino };
  return tfind (&obj, &data->known_objects, object_compare) != NULL;
}


static inline int
open_dir_stream (struct ftw_data *data, struct dir_data *dirp)
{
  int result = 0;

  if (data->dirstreams[data->actdir] != NULL)
    {
      /* Oh, oh.  We must close this stream.  Get all remaining
	 entries and store them as a list in the `content' member of
	 the `struct dir_data' variable.  */
      size_t bufsize = 1024;
      char *buf = malloc (bufsize);

      if (buf == NULL)
	result = -1;
      else
	{
	  DIR *st = data->dirstreams[data->actdir]->stream;
	  struct dirent64 *d;
	  size_t actsize = 0;

	  while ((d = __readdir64 (st)) != NULL)
	    {
	      size_t this_len = strlen (d->d_name);
	      if (actsize + this_len + 2 >= bufsize)
		{
		  char *newp;
		  bufsize += MAX (1024, 2 * this_len);
		  newp = realloc (buf, bufsize);
		  if (newp == NULL)
		    {
		      /* No more memory.  */
		      int save_err = errno;
		      free (buf);
		      __set_errno (save_err);
		      result = -1;
		      break;
		    }
		  buf = newp;
		}

	      *((char *) mempcpy (buf + actsize, d->d_name, this_len))
		= '\0';
	      actsize += this_len + 1;
	    }

	  /* Terminate the list with an additional NUL byte.  */
	  buf[actsize++] = '\0';

	  /* Shrink the buffer to what we actually need.  */
	  data->dirstreams[data->actdir]->content = realloc (buf, actsize);
	  if (data->dirstreams[data->actdir]->content == NULL)
	    {
	      int save_err = errno;
	      free (buf);
	      __set_errno (save_err);
	      result = -1;
	    }
	  else
	    {
	      closedir (st);
	      data->dirstreams[data->actdir]->stream = NULL;
	      data->dirstreams[data->actdir] = NULL;
	    }
	}
    }

  /* Open the new stream.  */
  if (result == 0)
    {
      assert (data->dirstreams[data->actdir] == NULL);

      dirp->stream = opendir (data->dirbuf);
      if (dirp->stream == NULL)
	result = -1;
      else
	{
	  dirp->content = NULL;
	  data->dirstreams[data->actdir] = dirp;

	  if (++data->actdir == data->maxdir)
	    data->actdir = 0;
	}
    }

  return result;
}


static inline int
process_entry (struct ftw_data *data, struct dir_data *dir, const char *name,
	       size_t namlen)
{
  struct STAT st;
  int result = 0;
  int flag = 0;

  if (name[0] == '.' && (name[1] == '\0'
			 || (name[1] == '.' && name[2] == '\0')))
    /* Don't process the "." and ".." entries.  */
    return 0;

  if (data->dirbufsize < data->ftw.base + namlen + 2)
    {
      /* Enlarge the buffer.  */
      char *newp;

      data->dirbufsize *= 2;
      newp = realloc (data->dirbuf, data->dirbufsize);
      if (newp == NULL)
	return -1;
      data->dirbuf = newp;
    }

  *((char *) mempcpy (data->dirbuf + data->ftw.base, name, namlen)) = '\0';

  if (((data->flags & FTW_PHYS)
       ? LXSTAT (data->dirbuf, &st)
       : XSTAT (data->dirbuf, &st)) < 0)
    {
      if (errno != EACCES && errno != ENOENT)
	result = -1;
      else if (!(data->flags & FTW_PHYS)
	       && LXSTAT (data->dirbuf, &st) == 0
	       && S_ISLNK (st.st_mode))
	flag = FTW_SLN;
      else
	flag = FTW_NS;
    }
  else
    {
      if (S_ISDIR (st.st_mode))
	flag = FTW_D;
      else if (S_ISLNK (st.st_mode))
	flag = FTW_SL;
      else
	flag = FTW_F;
    }

  if (result == 0
      && (flag == FTW_NS
	  || !(data->flags & FTW_MOUNT) || st.st_dev == data->dev))
    {
      if (flag == FTW_D)
	{
	  if ((data->flags & FTW_PHYS)
	      || (!find_object (data, &st)
		  /* Remember the object.  */
		  && (result = add_object (data, &st)) == 0))
	    {
	      result = ftw_dir (data, &st);

	      if (result == 0 && (data->flags & FTW_CHDIR))
		{
		  /* Change back to current directory.  */
		  int done = 0;
		  if (dir->stream != NULL)
		    if (fchdir (dirfd (dir->stream)) == 0)
		      done = 1;

		  if (!done)
		    {
		      if (data->ftw.base == 1)
			{
			  if (chdir ("/") < 0)
			    result = -1;
			}
		      else