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glibc/io/ftw.c

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/* File tree walker functions.
Copyright (C) 1996-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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, see
<https://www.gnu.org/licenses/>. */
#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
#ifdef _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 <fcntl.h>
#include <ftw.h>
#include <limits.h>
#include <search.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <not-cancel.h>
#include <sys/param.h>
#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>
#ifndef _LIBC
# undef __chdir
# define __chdir chdir
# undef __closedir
# define __closedir closedir
# undef __fchdir
# define __fchdir fchdir
# undef __getcwd
# define __getcwd(P, N) xgetcwd ()
extern char *xgetcwd (void);
# 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 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 NFTW_OLD_NAME __old_nftw
# define NFTW_NEW_NAME __new_nftw
# define INO_T ino_t
# define STRUCT_STAT stat
# ifdef _LIBC
# define LSTAT __lstat
# define STAT __stat
# define FSTATAT __fstatat
# else
# define LSTAT lstat
# define XTAT stat
# define FSTATAT fstatat
# 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
struct dir_data
{
DIR *stream;
int streamfd;
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;
};
static bool
ftw_allocate (struct ftw_data *data, size_t newsize)
{
void *newp = realloc (data->dirstreams, data->maxdir
* sizeof (struct dir_data *)
+ newsize);
if (newp == NULL)
return false;
data->dirstreams = newp;
data->dirbufsize = newsize;
data->dirbuf = (char *) data->dirstreams
+ data->maxdir * sizeof (struct dir_data *);
return true;
}
/* 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 STRUCT_STAT *st,
struct dir_data *old_dir);
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 int
add_object (struct ftw_data *data, struct 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 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 (int *dfdp, 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);
return -1;
}
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. */
void *content = realloc (buf, actsize);
data->dirstreams[data->actdir]->content = content;
if (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]->streamfd = -1;
data->dirstreams[data->actdir] = NULL;
}
}
}
/* Open the new stream. */
if (result == 0)
{
assert (data->dirstreams[data->actdir] == NULL);
if (dfdp != NULL && *dfdp != -1)
{
int fd = __openat64_nocancel (*dfdp, data->dirbuf + data->ftw.base,
O_RDONLY | O_DIRECTORY | O_NDELAY);
dirp->stream = NULL;
if (fd != -1 && (dirp->stream = __fdopendir (fd)) == NULL)
__close_nocancel_nostatus (fd);
}
else
{
const char *name;
if (data->flags & FTW_CHDIR)
{
name = data->dirbuf + data->ftw.base;
if (name[0] == '\0')
name = ".";
}
else
name = data->dirbuf;
dirp->stream = __opendir (name);
}
if (dirp->stream == NULL)
result = -1;
else
{
dirp->streamfd = __dirfd (dirp->stream);
dirp->content = NULL;
data->dirstreams[data->actdir] = dirp;
if (++data->actdir == data->maxdir)
data->actdir = 0;
}
}
return result;
}
static int
process_entry (struct ftw_data *data, struct dir_data *dir, const char *name,
size_t namlen, int d_type)
{
struct 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
&& !ftw_allocate (data, 2 * new_buflen))
return -1;
*((char *) __mempcpy (data->dirbuf + data->ftw.base, name, namlen)) = '\0';
int statres;
if (dir->streamfd != -1)
statres = FSTATAT (dir->streamfd, name, &st,
(data->flags & FTW_PHYS) ? AT_SYMLINK_NOFOLLOW : 0);
else
{
if ((data->flags & FTW_CHDIR) == 0)
name = data->dirbuf;
statres = ((data->flags & FTW_PHYS)
? LSTAT (name, &st)
: STAT (name, &st));
}
if (statres < 0)
{
if (errno != EACCES && errno != ENOENT)
result = -1;
else if (data->flags & FTW_PHYS)
flag = FTW_NS;
else
{
/* Old code left ST undefined for dangling DT_LNK without
FTW_PHYS set; a clarification at the POSIX level suggests
it should contain information about the link (ala lstat).
We do our best to fill in what data we can. */
if (dir->streamfd != -1)
statres = FSTATAT (dir->streamfd, name, &st,
AT_SYMLINK_NOFOLLOW);
else
statres = LSTAT (name, &st);
if (statres == 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, dir);
}
else
result = (*data->func) (data->dirbuf, &st, data->cvt_arr[flag],
&data->ftw);
}
if ((data->flags & FTW_ACTIONRETVAL) && result == FTW_SKIP_SUBTREE)
result = 0;
return result;
}
static int
__attribute ((noinline))
ftw_dir (struct ftw_data *data, struct STRUCT_STAT *st, struct dir_data *old_dir)
{
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 (old_dir == NULL ? NULL : &old_dir->streamfd,
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)
{
int save_err;
fail:
save_err = errno;
__closedir (dir.stream);
dir.streamfd = -1;
__set_errno (save_err);
if (data->actdir-- == 0)
data->actdir = data->maxdir - 1;
data->dirstreams[data->actdir] = NULL;
return result;
}
}
/* If necessary, change to this directory. */
if (data->flags & FTW_CHDIR)
{
if (__fchdir (__dirfd (dir.stream)) < 0)
{
result = -1;
goto fail;
}
}
/* 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)
{
int d_type = DT_UNKNOWN;
#ifdef _DIRENT_HAVE_D_TYPE
d_type = d->d_type;
#endif
result = process_entry (data, &dir, d->d_name, NAMLEN (d), d_type);
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);
dir.streamfd = -1;
__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');
// XXX Should store the d_type values as well?!
result = process_entry (data, &dir, runp, endp - runp, DT_UNKNOWN);
runp = endp + 1;
}
save_err = errno;
free (dir.content);
__set_errno (save_err);
}
if ((data->flags & FTW_ACTIONRETVAL) && result == FTW_SKIP_SIBLINGS)
result = 0;
/* 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);
if (old_dir
&& (data->flags & FTW_CHDIR)
&& (result == 0
|| ((data->flags & FTW_ACTIONRETVAL)
&& (result != -1 && result != FTW_STOP))))
{
/* Change back to the parent directory. */
int done = 0;
if (old_dir->stream != NULL)
if (__fchdir (__dirfd (old_dir->stream)) == 0)
done = 1;
if (!done)
{
if (data->ftw.base == 1)
{
if (__chdir ("/") < 0)
result = -1;
}
else
if (__chdir ("..") < 0)
result = -1;
}
}
return result;
}
static int
__attribute ((noinline))
ftw_startup (const char *dir, int is_nftw, void *func, int descriptors,
int flags)
{
struct ftw_data data = { .dirstreams = NULL };
struct STRUCT_STAT st;
int result = 0;
int save_err;
int cwdfd = -1;
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;
/* PATH_MAX is always defined when we get here. */
if (!ftw_allocate (&data, MAX (2 * strlen (dir), PATH_MAX)))
return -1;
memset (data.dirstreams, '\0', data.maxdir * sizeof (struct dir_data *));
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)
{
/* We have to be able to go back to the current working
directory. The best way to do this is to use a file
descriptor. */
cwdfd = __open (".", O_RDONLY | O_DIRECTORY);
if (cwdfd == -1)
{
/* Try getting the directory name. This can be needed if
the current directory is executable but not readable. */
if (errno == EACCES)
/* GNU extension ahead. */
cwd = __getcwd (NULL, 0);
if (cwd == NULL)
goto out_fail;
}
else if (data.maxdir > 1)
/* Account for the file descriptor we use here. */
--data.maxdir;
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;
if (data.flags & FTW_CHDIR)
{
name = data.dirbuf + data.ftw.base;
if (name[0] == '\0')
name = ".";
}
else
name = data.dirbuf;
if (((flags & FTW_PHYS)
? LSTAT (name, &st)
: STAT (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, NULL);
}
else
{
int flag = S_ISLNK (st.st_mode) ? FTW_SL : FTW_F;
result = (*data.func) (data.dirbuf, &st, data.cvt_arr[flag],
&data.ftw);
}
}
if ((flags & FTW_ACTIONRETVAL)
&& (result == FTW_SKIP_SUBTREE || result == FTW_SKIP_SIBLINGS))
result = 0;
}
/* Return to the start directory (if necessary). */
if (cwdfd != -1)
{
int save_err = errno;
__fchdir (cwdfd);
__close_nocancel_nostatus (cwdfd);
__set_errno (save_err);
}
else if (cwd != NULL)
{
int save_err = errno;
__chdir (cwd);
free (cwd);
__set_errno (save_err);
}
/* Free all memory. */
out_fail:
save_err = errno;
__tdestroy (data.known_objects, free);
free (data.dirstreams);
__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);
}
#ifndef NFTW_OLD_NAME
int
NFTW_NAME (const char *path, NFTW_FUNC_T func, int descriptors, int flags)
{
return ftw_startup (path, 1, func, descriptors, flags);
}
#else
# include <shlib-compat.h>
int NFTW_NEW_NAME (const char *, NFTW_FUNC_T, int, int);
int
NFTW_NEW_NAME (const char *path, NFTW_FUNC_T func, int descriptors, int flags)
{
if (flags
& ~(FTW_PHYS | FTW_MOUNT | FTW_CHDIR | FTW_DEPTH | FTW_ACTIONRETVAL))
{
__set_errno (EINVAL);
return -1;
}
return ftw_startup (path, 1, func, descriptors, flags);
}
versioned_symbol (libc, NFTW_NEW_NAME, NFTW_NAME, GLIBC_2_3_3);
# if SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_3_3)
/* Older nftw* version just ignored all unknown flags. */
int NFTW_OLD_NAME (const char *, NFTW_FUNC_T, int, int);
int
attribute_compat_text_section
NFTW_OLD_NAME (const char *path, NFTW_FUNC_T func, int descriptors, int flags)
{
flags &= (FTW_PHYS | FTW_MOUNT | FTW_CHDIR | FTW_DEPTH);
return ftw_startup (path, 1, func, descriptors, flags);
}
compat_symbol (libc, NFTW_OLD_NAME, NFTW_NAME, GLIBC_2_1);
# endif
#endif /* NFTW_OLD_NAME */
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