path: root/lib/ftw.c

/* File tree walker functions.
   Copyright (C) 1996-2001, 2002, 2003 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 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.  */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#if __GNUC__
# define alloca __builtin_alloca
#else
# if HAVE_ALLOCA_H
#  include <alloca.h>
# else
#  ifdef _AIX
 #  pragma alloca
#  else
char *alloca ();
#  endif
# endif
#endif

#include <sys/types.h>

#if defined _LIBC
# include <dirent.h>
# define NAMLEN(dirent) _D_EXACT_NAMLEN (dirent)
#else
# if HAVE_DIRENT_H
#  include <dirent.h>
#  define NAMLEN(dirent) strlen ((dirent)->d_name)
# else
#  define dirent direct
#  define NAMLEN(dirent) (dirent)->d_namlen
#  if HAVE_SYS_NDIR_H
#   include <sys/ndir.h>
#  endif
#  if HAVE_SYS_DIR_H
#   include <sys/dir.h>
#  endif
#  if HAVE_NDIR_H
#   include <ndir.h>
#  endif
# endif
#endif

#include <errno.h>
#include <ftw.h>
#include <limits.h>
#include <search.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#if HAVE_SYS_PARAM_H || defined _LIBC
# include <sys/param.h>
#endif
#ifdef _LIBC
# include <include/sys/stat.h>
#else
# include <sys/stat.h>
#endif

#if ! _LIBC && !HAVE_DECL_STPCPY && !defined stpcpy
char *stpcpy ();
#endif

#if ! _LIBC && ! defined HAVE_MEMPCPY && ! defined mempcpy
/* Be CAREFUL that there are no side effects in N.  */
# define mempcpy(D, S, N) ((void *) ((char *) memcpy (D, S, N) + (N)))
#endif

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

#include "save-cwd.h"

#ifndef _LIBC
# undef __chdir
# define __chdir chdir
# undef __closedir
# define __closedir closedir
# undef __fchdir
# define __fchdir fchdir
# undef __mempcpy
# define __mempcpy mempcpy
# undef __opendir
# define __opendir opendir
# undef __readdir64
# define __readdir64 readdir
# undef __stpcpy
# define __stpcpy stpcpy
# undef __tdestroy
# define __tdestroy tdestroy
# undef __tfind
# define __tfind tfind
# undef __tsearch
# define __tsearch tsearch
# undef internal_function
# define internal_function /* empty */
# undef dirent64
# define dirent64 dirent
# undef MAX
# define MAX(a, b) ((a) > (b) ? (a) : (b))
#endif

/* Arrange to make lstat calls go through the wrapper function
   on systems with an lstat function that does not dereference symlinks
   that are specified with a trailing slash.  */
#if ! _LIBC && ! LSTAT_FOLLOWS_SLASHED_SYMLINK
int rpl_lstat (const char *, struct stat *);
# undef lstat
# define lstat(Name, Stat_buf) rpl_lstat(Name, Stat_buf)
#endif

#ifndef __set_errno
# define __set_errno(Val) errno = (Val)
#endif

/* Support for the LFS API version.  */
#ifndef FTW_NAME
# define FTW_NAME ftw
# define NFTW_NAME nftw
# define INO_T ino_t
# define FTW_STAT stat
# ifdef _LIBC
#  define LXSTAT __lxstat
#  define XSTAT __xstat
# else
#  define LXSTAT(V,f,sb) lstat (f,sb)
#  define XSTAT(V,f,sb) stat (f,sb)
# endif
# define FTW_FUNC_T __ftw_func_t
# define NFTW_FUNC_T __nftw_func_t
#endif

/* We define PATH_MAX if the system does not provide a definition.
   This does not artificially limit any operation.  PATH_MAX is simply
   used as a guesstimate for the expected maximal path length.
   Buffers will be enlarged if necessary.  */
#ifndef PATH_MAX
# define PATH_MAX 1024
#endif

#ifndef S_IFMT
# define S_IFMT 0170000
#endif

#if STAT_MACROS_BROKEN
# undef S_ISLNK
#endif

#ifndef S_ISLNK
# ifdef S_IFLNK
#  define S_ISLNK(m) (((m) & S_IFMT) == S_IFLNK)
# else
#  define S_ISLNK(m) 0
# endif
#endif

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 known 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 invoked
   as `ftw', map each flag to the subset of values used by `ftw'.  */
static const int nftw_arr[] =
{
  /* Extract with:
     perl -ne '/^  (FTW_\w+)\b[^=]*$/ and print "$1, "' ftw_.h; echo */
  FTW_F, FTW_D, FTW_DNR, FTW_NS, FTW_DCH, FTW_DCHP, FTW_DPRE, FTW_SL, FTW_DP, FTW_SLN
};

static const int ftw_arr[] =
{
  /* Generate with:
     perl -ne '/^  (FTW_\w+)\b[^=]*$/ and print "$1, "' ftw_.h \
       | sed 's/_SL/_F/;s/_DP\>/_D/;s/_SLN/_NS/'; echo  */
  FTW_F, FTW_D, FTW_DNR, FTW_NS, FTW_DCH, FTW_DCHP, FTW_DPRE, FTW_F, FTW_D, FTW_NS
};

/* Ensure that each of the above arrays has the number of
   initializers corresponding to enum Ftw_option.  */
struct dummy
{
  int p1 [sizeof nftw_arr / sizeof nftw_arr[0] == FTW_N_MEMBERS ? 1 : -1];
  int p2 [sizeof nftw_arr / sizeof  ftw_arr[0] == FTW_N_MEMBERS ? 1 : -1];
};


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


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->ino > kp2->ino) - (kp1->ino < kp2->ino);
  if (cmp1 != 0)
    return cmp1;
  return (kp1->dev > kp2->dev) - (kp1->dev < kp2->dev);
}


static inline int
add_object (struct ftw_data *data, struct FTW_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 FTW_STAT *st)
{
  struct known_object obj;
  obj.dev = st->st_dev;
  obj.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 = NAMLEN (d);
	      if (actsize + this_len + 2 >= bufsize)
		{
		  char *newp;
		  bufsize += MAX (1024, 2 * this_len);
		  newp = (char *) 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)
    {
      const char *name = ((data->flags & FTW_CHDIR)
			  ? data->dirbuf + data->ftw.base: data->dirbuf);
      assert (data->dirstreams[data->actdir] == NULL);

      dirp->stream = __opendir (name);
      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 FTW_STAT st;
  int result = 0;
  int flag = 0;
  size_t new_buflen;

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

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

      data->dirbufsize = 2 * new_buflen;
      newp = (char *) 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_CHDIR) == 0)
    name = data->dirbuf;

  if (((data->flags & FTW_PHYS)
       ? LXSTAT (_STAT_VER, name, &st)
       : XSTAT (_STAT_VER, name, &st)) < 0)
    {
      if (errno != EACCES && errno != ENOENT)
	result = -1;
      else if (!(data->flags & FTW_PHYS)
	       && LXSTAT (_STAT_VER, name, &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))
	    {
	      /* When processing a directory as part of a depth-first traversal,
		 invoke the user's callback function with type=FTW_DPRE
		 just before processing any entry in that directory.
		 And if the callback sets ftw.skip, then don't process
		 any entries of the directory.  */
	      if ((data->flags & FTW_DEPTH)
		  && (result = (*data->func) (data->dirbuf, &st, FTW_DPRE,
					      &data->ftw)) == 0
		  && ! data->ftw.skip)
		result = ftw_dir (data, &st);

	      if (result == 0 && (data->flags & FTW_CHDIR))
		{
		  /* Change back to the parent 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
			if (__chdir ("..") < 0)
			  result = -1;
		    }

		  if (result < 0)
		    {
		      result = (*data->func) (data->dirbuf, NULL, FTW_DCHP,
				&data->ftw);
		    }
		}
	    }
	}
      else
	result = (*data->func) (data->dirbuf, &st, data->cvt_arr[flag],
				&data->ftw);
    }

  return result;
}


static int
internal_function
ftw_dir (struct ftw_data *data, struct FTW_STAT *st)
{
  struct dir_data dir;
  struct dirent64 *d;
  int previous_base = data->ftw.base;
  int result;
  char *startp;

  /* Open the stream for this directory.  This might require that
     another stream has to be closed.  */
  result = open_dir_stream (data, &dir);
  if (result != 0)
    {
      if (errno == EACCES)
	/* We cannot read the directory.  Signal this with a special flag.  */
	result = (*data->func) (data->dirbuf, st, FTW_DNR, &data->ftw);

      return result;
    }

  /* First, report the directory (if not depth-first).  */
  if (!(data->flags & FTW_DEPTH))
    {
      result = (*data->func) (data->dirbuf, st, FTW_D, &data->ftw);
      if (result != 0)
	return result;
    }

  /* If necessary, change to this directory.  */
  if (data->flags & FTW_CHDIR)
    {
      if (__fchdir (dirfd (dir.stream)) < 0)
	{
	  if (errno == ENOSYS)
	    {
	      if (__chdir (data->dirbuf) < 0)
		result = -1;
	    }
	  else
	    result = -1;
	}

      if (result != 0)
	{
	  int save_err = errno;
	  __closedir (dir.stream);
	  __set_errno (save_err);

	  if (data->actdir-- == 0)
	    data->actdir = data->maxdir - 1;
	  data->dirstreams[data->actdir] = NULL;

	  /* We cannot change to the directory.
	     Signal this with a special flag.  */
	  result = (*data->func) (data->dirbuf, st, FTW_DCH, &data->ftw);

	  return result;
	}
    }

  /* Next, update the `struct FTW' information.  */
  ++data->ftw.level;
  startp = strchr (data->dirbuf, '\0');
  /* There always must be a directory name.  */
  assert (startp != data->dirbuf);
  if (startp[-1] != '/')
    *startp++ = '/';
  data->ftw.base = startp - data->dirbuf;

  while (dir.stream != NULL && (d = __readdir64 (dir.stream)) != NULL)
    {
      result = process_entry (data, &dir, d->d_name, NAMLEN (d));
      if (result != 0)
	break;
    }

  if (dir.stream != NULL)
    {
      /* The stream is still open.  I.e., we did not need more
	 descriptors.  Simply close the stream now.  */
      int save_err = errno;

      assert (dir.content == NULL);

      __closedir (dir.stream);
      __set_errno (save_err);

      if (data->actdir-- == 0)
	data->actdir = data->maxdir - 1;
      data->dirstreams[data->actdir] = NULL;
    }
  else
    {
      int save_err;
      char *runp = dir.content;

      while (result == 0 && *runp != '\0')
	{
	  char *endp = strchr (runp, '\0');

	  result = process_entry (data, &dir, runp, endp - runp);

	  runp = endp + 1;
	}

      save_err = errno;
      free (dir.content);
      __set_errno (save_err);
    }

  /* Prepare the return, revert the `struct FTW' information.
     If ftw.base is 1, be careful to preserve the `/'.  */
  data->dirbuf[data->ftw.base == 1 ? 1 : data->ftw.base - 1] = '\0';
  --data->ftw.level;
  data->ftw.base = previous_base;

  /* Finally, if we process depth-first report the directory.  */
  if (result == 0 && (data->flags & FTW_DEPTH))
    result = (*data->func) (data->dirbuf, st, FTW_DP, &data->ftw);

  return result;
}


#ifdef _LIBC
# define ISSLASH(C) ((C) == '/')
# define FILESYSTEM_PREFIX_LEN(Filename) 0
#endif

/* In general, we can't use the builtin `basename' function if available,
   since it has different meanings in different environments.
   In some environments the builtin `basename' modifies its argument.

   Return the address of the last file name component of NAME.  If
   NAME has no file name components because it is all slashes, return
   NAME if it is empty, the address of its last slash otherwise.  */

static char *
base_name (char const *name)
{
  char const *base = name + FILESYSTEM_PREFIX_LEN (name);
  char const *p;

  for (p = base; *p; p++)
    {
      if (ISSLASH (*p))
	{
	  /* Treat multiple adjacent slashes like a single slash.  */
	  do p++;
	  while (ISSLASH (*p));

	  /* If the file name ends in slash, use the trailing slash as
	     the basename if no non-slashes have been found.  */
	  if (! *p)
	    {
	      if (ISSLASH (*base))
		base = p - 1;
	      break;
	    }

	  /* *P is a non-slash preceded by a slash.  */
	  base = p;
	}
    }

  return (char *) base;
}


static int
internal_function
ftw_startup (const char *dir, int is_nftw, NFTW_FUNC_T func, int descriptors,
	     int flags)
{
  struct ftw_data data;
  struct FTW_STAT st;
  int result = 0;
  int save_err;
  struct saved_cwd cwd;
  size_t dir_len;

  /* First make sure the parameters are reasonable.  */
  if (dir[0] == '\0')
    {
      __set_errno (ENOENT);
      return -1;
    }

  data.maxdir = descriptors < 1 ? 1 : descriptors;
  data.actdir = 0;
  data.dirstreams = (struct dir_data **) alloca (data.maxdir
						 * sizeof (struct dir_data *));
  if (data.dirstreams == NULL)
    return -1;
  memset (data.dirstreams, '\0', data.maxdir * sizeof (struct dir_data *));

  /* PATH_MAX is always defined when we get here.  */
  dir_len = strlen (dir);
  data.dirbufsize = MAX (2 * dir_len, PATH_MAX);
  data.dirbuf = (char *) malloc (data.dirbufsize);
  if (data.dirbuf == NULL)
    return -1;
  memcpy (data.dirbuf, dir, dir_len + 1);

  data.ftw.level = 0;

  /* Find offset of basename.  */
  data.ftw.base = base_name (data.dirbuf) - data.dirbuf;

  data.flags = flags;

  /* This assignment might seem to be strange but it is what we want.
     The trick is that the first three arguments to the `ftw' and
     `nftw' callback functions are equal.  Therefore we can call in
     every case the callback using the format of the `nftw' version
     and get the correct result since the stack layout for a function
     call in C allows this.  */
  data.func = func;

  /* Since we internally use the complete set of FTW_* values we need
     to reduce the value range before calling a `ftw' callback.  */
  data.cvt_arr = is_nftw ? nftw_arr : ftw_arr;

  /* No object known so far.  */
  data.known_objects = NULL;

  /* Now go to the directory containing the initial file/directory.  */
  if (flags & FTW_CHDIR)
    {
      if (save_cwd (&cwd))
	result = -1;
      else if (data.ftw.base > 0)
	{
	  /* Change to the directory the file is in.  In data.dirbuf
	     we have a writable copy of the file name.  Just NUL
	     terminate it for now and change the directory.  */
	  if (data.ftw.base == 1)
	    /* I.e., the file is in the root directory.  */
	    result = __chdir ("/");
	  else
	    {
	      char ch = data.dirbuf[data.ftw.base - 1];
	      data.dirbuf[data.ftw.base - 1] = '\0';
	      result = __chdir (data.dirbuf);
	      data.dirbuf[data.ftw.base - 1] = ch;
	    }
	}
    }

  /* Get stat info for start directory.  */
  if (result == 0)
    {
      const char *name = ((data.flags & FTW_CHDIR)
			  ? data.dirbuf + data.ftw.base
			  : data.dirbuf);

      if (((flags & FTW_PHYS)
	   ? LXSTAT (_STAT_VER, name, &st)
	   : XSTAT (_STAT_VER, name, &st)) < 0)
	{
	  if (!(flags & FTW_PHYS)
	      && errno == ENOENT
	      && LXSTAT (_STAT_VER, name, &st) == 0
	      && S_ISLNK (st.st_mode))
	    result = (*data.func) (data.dirbuf, &st, data.cvt_arr[FTW_SLN],
				   &data.ftw);
	  else
	    /* No need to call the callback since we cannot say anything
	       about the object.  */
	    result = -1;
	}
      else
	{
	  if (S_ISDIR (st.st_mode))
	    {
	      /* Remember the device of the initial directory in case
		 FTW_MOUNT is given.  */
	      data.dev = st.st_dev;

	      /* We know this directory now.  */
	      if (!(flags & FTW_PHYS))
		result = add_object (&data, &st);

	      if (result == 0)
		{
		  /* If we're doing a depth-first traversal, give the user
		     a chance to prune the top-level directory.  */
		  if ((flags & FTW_DEPTH)
		      && (result = (*data.func) (data.dirbuf, &st, FTW_DPRE,
						 &data.ftw)) == 0
		      && ! data.ftw.skip)
		    result = ftw_dir (&data, &st);
		}
	    }
	  else
	    {
	      int flag = S_ISLNK (st.st_mode) ? FTW_SL : FTW_F;

	      result = (*data.func) (data.dirbuf, &st, data.cvt_arr[flag],
				     &data.ftw);
	    }
	}
    }

  /* Return to the start directory (if necessary).  */
  if (flags & FTW_CHDIR)
    {
      save_err = errno;
      /* If restore_cwd fails and there wasn't a prior failure,
	 then let this new errno override any prior value.
	 FIXME: ideally, we'd be able to return some indication
	 of what the failure means.  Otherwise, the caller will
	 have a hard time distinguishing between e.g., `out of memory'
	 and this sort of failure.  */
      if (restore_cwd (&cwd) && result == 0)
	{
	  save_err = errno;
	  result = -1;
	}
      free_cwd (&cwd);

      __set_errno (save_err);
    }

  /* Free all memory.  */
  save_err = errno;
  __tdestroy (data.known_objects, free);
  free (data.dirbuf);
  __set_errno (save_err);

  return result;
}



/* Entry points.  */

int
FTW_NAME (path, func, descriptors)
     const char *path;
     FTW_FUNC_T func;
     int descriptors;
{
  return ftw_startup (path, 0, (NFTW_FUNC_T) func, descriptors, 0);
}

int
NFTW_NAME (path, func, descriptors, flags)
     const char *path;
     NFTW_FUNC_T func;
     int descriptors;
     int flags;
{
  return ftw_startup (path, 1, func, descriptors, flags);
}