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/*	$OpenBSD: scandir.c,v 1.21 2019/06/28 13:32:41 deraadt Exp $ */
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/*
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 * This is a modified verision of scandir that takes an explicit
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 * directory file descriptor as parameter.
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 */
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/*
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 * Copyright (c) 1983, 1993
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 *	The Regents of the University of California.  All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 * 1. Redistributions of source code must retain the above copyright
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 *    notice, this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    notice, this list of conditions and the following disclaimer in the
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 *    documentation and/or other materials provided with the distribution.
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 * 3. Neither the name of the University nor the names of its contributors
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 *    may be used to endorse or promote products derived from this software
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 *    without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 * SUCH DAMAGE.
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 */
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/*
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 * Scan the directory fd calling select to make a list of selected
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 * directory entries then sort using qsort and compare routine dcomp.
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 * Returns the number of entries and a pointer to a list of pointers to
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 * struct dirent (through namelist). Returns -1 if there were any errors.
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 */
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#include "gmid.h"
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <dirent.h>
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#include <errno.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#define MAXIMUM(a, b)	(((a) > (b)) ? (a) : (b))
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/*
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 * The DIRSIZ macro is the minimum record length which will hold the directory
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 * entry.  This requires the amount of space in struct dirent without the
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 * d_name field, plus enough space for the name and a terminating nul byte
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 * (dp->d_namlen + 1), rounded up to a 4 byte boundary.
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 */
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#undef DIRSIZ
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#define DIRSIZ(dp, namlen)						\
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	((sizeof(struct dirent) - sizeof(dp)->d_name) +			\
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	    ((namlen + 1 + 3) &~ 3))
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int
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scandir_fd(int fd, struct dirent ***namelist,
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    int (*select)(const struct dirent *),
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    int (*dcomp)(const struct dirent **, const struct dirent **))
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{
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	struct dirent *d, *p, **names = NULL;
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	size_t arraysz, namlen, nitems = 0;
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	struct stat stb;
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	DIR *dirp;
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	if ((dirp = fdopendir(fd)) == NULL)
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		return (-1);
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	if (fstat(fd, &stb) == -1)
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		goto fail;
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	/*
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	 * estimate the array size by taking the size of the directory file
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	 * and dividing it by a multiple of the minimum size entry.
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	 */
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	arraysz = MAXIMUM(stb.st_size / 24, 16);
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	if (arraysz > SIZE_MAX / sizeof(struct dirent *)) {
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		errno = ENOMEM;
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		goto fail;
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	}
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	names = calloc(arraysz, sizeof(struct dirent *));
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	if (names == NULL)
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		goto fail;
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	while ((d = readdir(dirp)) != NULL) {
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		if (select != NULL && !(*select)(d))
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			continue;	/* just selected names */
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		/*
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		 * Check to make sure the array has space left and
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		 * realloc the maximum size.
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		 */
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		if (nitems >= arraysz) {
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			struct dirent **nnames;
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			if (fstat(fd, &stb) == -1)
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				goto fail;
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			arraysz *= 2;
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			if (SIZE_MAX / sizeof(struct dirent *) < arraysz)
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				goto fail;
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			nnames = reallocarray(names,
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			    arraysz, sizeof(struct dirent *));
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			if (nnames == NULL)
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				goto fail;
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			names = nnames;
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		}
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		/*
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		 * Make a minimum size copy of the data
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		 */
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		namlen = strlen(d->d_name);
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		p = malloc(DIRSIZ(d, namlen));
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		if (p == NULL)
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			goto fail;
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		p->d_ino = d->d_ino;
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		p->d_type = d->d_type;
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		memcpy(p->d_name, d->d_name, namlen + 1);
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		names[nitems++] = p;
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	}
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	closedir(dirp);
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	if (nitems && dcomp != NULL)
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		qsort(names, nitems, sizeof(struct dirent *),
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		    (int(*)(const void *, const void *))dcomp);
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	*namelist = names;
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	return (nitems);
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fail:
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	while (nitems > 0)
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		free(names[--nitems]);
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	free(names);
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	closedir(dirp);
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	return (-1);
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}
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int
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select_non_dot(const struct dirent *d)
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{
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	return strcmp(d->d_name, ".");
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}
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int
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select_non_dotdot(const struct dirent *d)
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{
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	return strcmp(d->d_name, ".") && strcmp(d->d_name, "..");
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}