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/* savedir.c -- save the list of files in a directory in a string
Copyright (C) 1990, 1997-2001, 2003-2006, 2009-2020 Free Software
Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* Written by David MacKenzie <djm@gnu.ai.mit.edu>. */
#include <config.h>
#include "savedir.h"
#include <sys/types.h>
#include <errno.h>
#include "dirent--.h"
#ifndef _D_EXACT_NAMLEN
# define _D_EXACT_NAMLEN(dp) strlen ((dp)->d_name)
#endif
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include "xalloc.h"
typedef struct
{
char *name;
#if D_INO_IN_DIRENT
ino_t ino;
#endif
} direntry_t;
/* Compare the names of two directory entries */
static int
direntry_cmp_name (void const *a, void const *b)
{
direntry_t const *dea = a;
direntry_t const *deb = b;
return strcmp (dea->name, deb->name);
}
#if D_INO_IN_DIRENT
/* Compare the inode numbers of two directory entries */
static int
direntry_cmp_inode (void const *a, void const *b)
{
direntry_t const *dea = a;
direntry_t const *deb = b;
return dea->ino < deb->ino ? -1 : dea->ino > deb->ino;
}
#endif
typedef int (*comparison_function) (void const *, void const *);
static comparison_function const comparison_function_table[] =
{
0,
direntry_cmp_name
#if D_INO_IN_DIRENT
, direntry_cmp_inode
#endif
};
/* Return a freshly allocated string containing the file names
in directory DIRP, separated by '\0' characters;
the end is marked by two '\0' characters in a row.
Returned values are sorted according to OPTION.
Return NULL (setting errno) if DIRP cannot be read.
If DIRP is NULL, return NULL without affecting errno. */
char *
streamsavedir (DIR *dirp, enum savedir_option option)
{
char *name_space = NULL;
size_t allocated = 0;
direntry_t *entries = NULL;
size_t entries_allocated = 0;
size_t entries_used = 0;
size_t used = 0;
int readdir_errno;
comparison_function cmp = comparison_function_table[option];
if (dirp == NULL)
return NULL;
for (;;)
{
struct dirent const *dp;
char const *entry;
errno = 0;
dp = readdir (dirp);
if (! dp)
break;
/* Skip "", ".", and "..". "" is returned by at least one buggy
implementation: Solaris 2.4 readdir on NFS file systems. */
entry = dp->d_name;
if (entry[entry[0] != '.' ? 0 : entry[1] != '.' ? 1 : 2] != '\0')
{
size_t entry_size = _D_EXACT_NAMLEN (dp) + 1;
if (cmp)
{
if (entries_allocated == entries_used)
{
size_t n = entries_allocated;
entries = x2nrealloc (entries, &n, sizeof *entries);
entries_allocated = n;
}
entries[entries_used].name = xstrdup (entry);
#if D_INO_IN_DIRENT
entries[entries_used].ino = dp->d_ino;
#endif
entries_used++;
}
else
{
if (allocated - used <= entry_size)
{
size_t n = used + entry_size;
if (n < used)
xalloc_die ();
name_space = x2nrealloc (name_space, &n, 1);
allocated = n;
}
memcpy (name_space + used, entry, entry_size);
}
used += entry_size;
}
}
readdir_errno = errno;
if (readdir_errno != 0)
{
free (entries);
free (name_space);
errno = readdir_errno;
return NULL;
}
if (cmp)
{
size_t i;
if (entries_used)
qsort (entries, entries_used, sizeof *entries, cmp);
name_space = xmalloc (used + 1);
used = 0;
for (i = 0; i < entries_used; i++)
{
char *dest = name_space + used;
used += stpcpy (dest, entries[i].name) - dest + 1;
free (entries[i].name);
}
free (entries);
}
else if (used == allocated)
name_space = xrealloc (name_space, used + 1);
name_space[used] = '\0';
return name_space;
}
/* Return a freshly allocated string containing the file names
in directory DIR, separated by '\0' characters;
the end is marked by two '\0' characters in a row.
Return NULL (setting errno) if DIR cannot be opened, read, or closed. */
char *
savedir (char const *dir, enum savedir_option option)
{
DIR *dirp = opendir (dir);
if (! dirp)
return NULL;
else
{
char *name_space = streamsavedir (dirp, option);
if (closedir (dirp) != 0)
{
int closedir_errno = errno;
free (name_space);
errno = closedir_errno;
return NULL;
}
return name_space;
}
}
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