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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.  */

#define _GNU_SOURCE
#include <features.h>


#if defined (__UCLIBC_HAS_LFS__) && defined L_ftw64
#define L_ftw

/* If Large file support is enabled, transparently remap
 * things to use the 64-bit interfaces */
#if defined _FILE_OFFSET_BITS && _FILE_OFFSET_BITS != 64 
#undef _FILE_OFFSET_BITS
#define     _FILE_OFFSET_BITS   64
#endif
#ifndef __USE_LARGEFILE64
# define __USE_LARGEFILE64  1
#endif
#ifndef __USE_FILE_OFFSET64
# define __USE_FILE_OFFSET64  1
#endif

#define FTW_NAME ftw64
#define NFTW_NAME nftw64
#define INO_T ino64_t
#define STAT stat64
#define LSTAT lstat64
#define XSTAT stat64
#define FTW_FUNC_T __ftw64_func_t
#define NFTW_FUNC_T __nftw64_func_t
#else
#define FTW_NAME ftw
#define NFTW_NAME nftw
#define INO_T ino_t
#define STAT stat
#define LSTAT lstat
#define XSTAT stat
#define FTW_FUNC_T __ftw_func_t
#define NFTW_FUNC_T __nftw_func_t
#endif

#ifdef L_ftw

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

/* 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

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[] =
{
    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) 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 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;
    obj.dev = st->st_dev;
    obj.ino = st->st_ino;
    return tfind (&obj, &data->known_objects, object_compare) != NULL;
}


static inline int
__attribute ((always_inline))
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 dirent *d;
          size_t actsize = 0;

          while ((d = readdir (st)) != NULL)
          {
            size_t this_len = _D_EXACT_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 int
internal_function
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;
    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)
            ? LSTAT (name, &st)
            : XSTAT (name, &st)) < 0)
    {
      if (errno != EACCES && errno != ENOENT)
          result = -1;
      else if (!(data->flags & FTW_PHYS)
            && LSTAT (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))
          {
            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;
                }
            }
          }
      }
      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 STAT *st)
{
    struct dir_data dir;
    struct dirent *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)
      {
          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;

          return -1;
      }
    }

    /* 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 = readdir (dir.stream)) != NULL)
    {
      result = process_entry (data, &dir, d->d_name, _D_EXACT_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.  */
    data->dirbuf[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;
}


static int
internal_function
ftw_startup (const char *dir, int is_nftw, void *func, int descriptors, int flags)
{
    struct ftw_data data;
    struct STAT st;
    int result = 0;
    int save_err;
    char *cwd = NULL;
    char *cp;

    /* First make sure the parameters are reasonable.  */
    if (unlikely(dir==NULL || *dir=='\0')) {
      __set_errno (ENOENT);
      return -1;
    }
    if ((strlen(dir)+1) > NAME_MAX) {
      __set_errno(ENAMETOOLONG);
      return -1;
    }

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

    /* PATH_MAX is always defined when we get here.  */
    data.dirbufsize = MAX (2 * strlen (dir), PATH_MAX);
    data.dirbuf = (char *) malloc (data.dirbufsize);
    if (data.dirbuf == NULL)
      return -1;
    cp = stpcpy (data.dirbuf, dir);
    /* Strip trailing slashes.  */
    while (cp > data.dirbuf + 1 && cp[-1] == '/')
      --cp;
    *cp = '\0';

    data.ftw.level = 0;

    /* Find basename.  */
    while (cp > data.dirbuf && cp[-1] != '/')
      --cp;
    data.ftw.base = cp - 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 = (NFTW_FUNC_T) 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)
    {
      /* GNU extension ahead.  */
      cwd =  getcwd (NULL, 0);
      if (cwd == NULL)
          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)
                ? LSTAT (name, &st)
                : XSTAT (name, &st)) < 0)
      {
          if (!(flags & FTW_PHYS)
                && errno == ENOENT
                && LSTAT (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)
                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 (cwd != NULL)
    {
      int save_err = errno;
      chdir (cwd);
      free (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 (const char *path, FTW_FUNC_T func, int descriptors)
{
    return ftw_startup (path, 0, func, descriptors, 0);
}

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

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