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glibc/io/ftw.c

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/* File tree walker functions.
Copyright (C) 1996, 1997, 1998, 1999, 2000 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 Library General Public License as
published by the Free Software Foundation; either version 2 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#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 <include/sys/stat.h>
/* #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 DIRENT dirent
# define READDIR __readdir
# define LXSTAT __lxstat
# define XSTAT __xstat
# define FTW_FUNC_T __ftw_func_t
# define NFTW_FUNC_T __nftw_func_t
#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 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) 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->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 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 = 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 (_STAT_VER, data->dirbuf, &st)
: XSTAT (_STAT_VER, data->dirbuf, &st)) < 0)
{
if (errno != EACCES && errno != ENOENT)
result = -1;
else if (!(data->flags & FTW_PHYS)
&& LXSTAT (_STAT_VER, 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
{
/* Please note that we overwrite a slash. */
data->dirbuf[data->ftw.base - 1] = '\0';
if (__chdir (data->dirbuf) < 0)
result = -1;
data->dirbuf[data->ftw.base - 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)
{
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;
return result;
}
}
/* Next, update the `struct FTW' information. */
++data->ftw.level;
startp = strchr (data->dirbuf, '\0');
*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;
assert (result == 0);
while (*runp != '\0')
{
char *endp = strchr (runp, '\0');
result = process_entry (data, &dir, runp, endp - runp);
if (result != 0)
break;
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 (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 *));
memset (data.dirstreams, '\0', data.maxdir * sizeof (struct dir_data *));
#ifdef PATH_MAX
data.dirbufsize = MAX (2 * strlen (dir), PATH_MAX);
#else
data.dirbufsize = 2 * strlen (dir);
#endif
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) && data.ftw.base > 0)
{
/* GNU extension ahead. */
cwd = __getcwd (NULL, 0);
if (cwd == NULL)
result = -1;
else
{
/* 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)
{
if (((flags & FTW_PHYS)
? LXSTAT (_STAT_VER, data.dirbuf, &st)
: XSTAT (_STAT_VER, data.dirbuf, &st)) < 0)
{
if (errno == EACCES)
result = (*data.func) (data.dirbuf, &st, FTW_NS, &data.ftw);
else if (!(flags & FTW_PHYS)
&& errno == ENOENT
&& LXSTAT (_STAT_VER, dir, &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 (path, func, descriptors)
const char *path;
FTW_FUNC_T func;
int descriptors;
{
return ftw_startup (path, 0, 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);
}
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