/****************************************************************************
* libs/libc/dirent/lib_scandir.c
*
* Copyright (C) 2019 Gregory Nutt. All rights reserved.
* Author: Michael Jung <mijung@gmx.net>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <string.h>
#include <dirent.h>
#include <errno.h>
#include <stdlib.h>
/* The scandir() function is not appropriate for use within the kernel in its
* current form because it uses user space memory allocators and modifies
* the errno value.
*/
#ifndef __KERNEL__
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: scandir
*
* Description:
* The scandir() function scans the directory dirp, calling filter() on each
* directory entry. Entries for which filter() returns nonzero are stored
* in strings allocated via malloc(), sorted using qsort() with comparison
* function compar(), and collected in array namelist which is allocated via
* malloc(). If filter is NULL, all entries are selected.
*
* Input Parameters:
* path - Pathname of the directory to scan
* namelist - An array of pointers to directory entries, which is allocated
* by scandir via malloc. Each directory entry is allocated via
* malloc as well. The caller is responsible to free said
objects.
* filter - Directory entries for which filter returns zero are not
* included in the namelist. If filter is NULL, all entries are
* included.
* compar - Comparison function used with qsort() to sort the namelist.
*
* Returned Value:
* If successful, the scandir() function returns the number of entries in
* the namelist. Otherwise, it returns -1 and errno is set to indicate the
* error.
*
****************************************************************************/
int scandir(FAR const char *path, FAR struct dirent ***namelist,
CODE int (*filter)(FAR const struct dirent *),
CODE int (*compar)(FAR const struct dirent **,
FAR const struct dirent **))
{
FAR struct dirent *d;
FAR struct dirent *dnew;
FAR struct dirent **list = NULL;
size_t listsize = 0;
size_t cnt = 0;
int errsv;
int result;
FAR DIR *dirp;
/* This scandir implementation relies on errno being set by other service
* functions that it is calling to figure if it was successful. We save
* the original errno value to be able to restore it in case of success.
*/
errsv = get_errno();
dirp = opendir(path);
if (!dirp)
{
return -1;
}
/* opendir might have set errno. Reset to zero. */
set_errno(0);
for (d = readdir(dirp); d != NULL; d = readdir(dirp))
{
size_t dsize;
/* If the caller provided a filter function which tells scandir to skip
* the current directory entry, do so.
*/
if (filter && !filter(d))
{
continue;
}
/* The caller provided filter function might have set errno. Reset to
* zero.
*/
set_errno(0);
/* Grow the directory entry list, if required. */
if (cnt == listsize)
{
struct dirent **newlist;
if (!listsize)
{
listsize = 4;
}
else
{
listsize *= 2;
}
newlist = realloc(list, listsize * sizeof(*list));
if (!newlist)
{
/* realloc failed and set errno. This will tell follow up code
* that we failed.
*/
break;
}
list = newlist;
}
/* Allocate a new directory entry, but restrict its heap size to what is
* really required given the directories' path name.
*/
dsize = (size_t)(&d->d_name[strlen(d->d_name) + 1] - (char *)d);
dnew = malloc(dsize);
if (!dnew)
{
/* malloc failed and set errno. This will tell follow up code that
* we failed.
*/
break;
}
/* Copy directory entry to newly allocated one and update the list
* accordingly.
*/
memcpy(dnew, d, dsize);
list[cnt] = dnew;
cnt++;
/* Some service function might have set errno as a side effect. Reset
* to zero.
*/
set_errno(0);
}
if (get_errno() == 0)
{
/* If the caller provided a comparison function, use it to sort the list
* of directory entries.
*/
if (compar)
{
qsort(list, cnt, sizeof(*list),
(CODE int (*)(FAR const void *, FAR const void *))compar);
}
/* Set the output parameters. */
*namelist = list;
result = (int)cnt;
}
else
{
size_t i;
/* Something failed along the way. Clean up. */
for (i = 0; i < cnt; i++)
{
free(list[i]);
}
free(list);
result = -1;
}
closedir(dirp);
if (result >= 0)
{
/* Restore original errno value in case of success. */
set_errno(errsv);
}
return result;
}
#endif /* __KERNEL__ */