1 /*	$OpenBSD: scandir.c,v 1.21 2019/06/28 13:32:41 deraadt Exp $ */
2 
3 /*
4  * This is a modified verision of scandir that takes an explicit
5  * directory file descriptor as parameter.
6  */
7 
8 /*
9  * Copyright (c) 1983, 1993
10  *	The Regents of the University of California.  All rights reserved.
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in the
19  *    documentation and/or other materials provided with the distribution.
20  * 3. Neither the name of the University nor the names of its contributors
21  *    may be used to endorse or promote products derived from this software
22  *    without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34  * SUCH DAMAGE.
35  */
36 
37 /*
38  * Scan the directory fd calling select to make a list of selected
39  * directory entries then sort using qsort and compare routine dcomp.
40  * Returns the number of entries and a pointer to a list of pointers to
41  * struct dirent (through namelist). Returns -1 if there were any errors.
42  */
43 
44 #include "gmid.h"
45 
46 #include <sys/types.h>
47 #include <sys/stat.h>
48 
49 #include <dirent.h>
50 #include <errno.h>
51 #include <stdint.h>
52 #include <stdlib.h>
53 #include <string.h>
54 
55 #define MAXIMUM(a, b)	(((a) > (b)) ? (a) : (b))
56 
57 /*
58  * The DIRSIZ macro is the minimum record length which will hold the directory
59  * entry.  This requires the amount of space in struct dirent without the
60  * d_name field, plus enough space for the name and a terminating nul byte
61  * (dp->d_namlen + 1), rounded up to a 4 byte boundary.
62  */
63 #undef DIRSIZ
64 #define DIRSIZ(dp)							\
65 	((sizeof(struct dirent) - sizeof(dp)->d_name) +			\
66 	    (((dp)->d_namlen + 1 + 3) &~ 3))
67 
68 int
69 scandir_fd(int fd, struct dirent ***namelist,
70     int (*select)(const struct dirent *),
71     int (*dcomp)(const struct dirent **, const struct dirent **))
72 {
73 	struct dirent *d, *p, **names = NULL;
74 	size_t /* arraysz, */ nitems = 0;
75 	long arraysz;
76 	struct stat stb;
77 	DIR *dirp;
78 
79 	if ((dirp = fdopendir(fd)) == NULL)
80 		return (-1);
81 	if (fstat(fd, &stb) == -1)
82 		goto fail;
83 
84 	/*
85 	 * estimate the array size by taking the size of the directory file
86 	 * and dividing it by a multiple of the minimum size entry.
87 	 */
88 	arraysz = MAXIMUM(stb.st_size / 24, 16);
89 	if (arraysz > SIZE_MAX / sizeof(struct dirent *)) {
90 		errno = ENOMEM;
91 		goto fail;
92 	}
93 	names = calloc(arraysz, sizeof(struct dirent *));
94 	if (names == NULL)
95 		goto fail;
96 
97 	while ((d = readdir(dirp)) != NULL) {
98 		if (select != NULL && !(*select)(d))
99 			continue;	/* just selected names */
100 
101 		/*
102 		 * Check to make sure the array has space left and
103 		 * realloc the maximum size.
104 		 */
105 		if (nitems >= arraysz) {
106 			struct dirent **nnames;
107 
108 			if (fstat(fd, &stb) == -1)
109 				goto fail;
110 
111 			arraysz *= 2;
112 			if (SIZE_MAX / sizeof(struct dirent *) < arraysz)
113 				goto fail;
114 			nnames = reallocarray(names,
115 			    arraysz, sizeof(struct dirent *));
116 			if (nnames == NULL)
117 				goto fail;
118 
119 			names = nnames;
120 		}
121 
122 		/*
123 		 * Make a minimum size copy of the data
124 		 */
125 		p = malloc(DIRSIZ(d));
126 		if (p == NULL)
127 			goto fail;
128 
129 		p->d_ino = d->d_ino;
130 		p->d_type = d->d_type;
131 		p->d_reclen = d->d_reclen;
132 		p->d_namlen = d->d_namlen;
133 		bcopy(d->d_name, p->d_name, p->d_namlen + 1);
134 		names[nitems++] = p;
135 	}
136 	closedir(dirp);
137 	if (nitems && dcomp != NULL)
138 		qsort(names, nitems, sizeof(struct dirent *),
139 		    (int(*)(const void *, const void *))dcomp);
140 	*namelist = names;
141 	return (nitems);
142 
143 fail:
144 	while (nitems > 0)
145 		free(names[--nitems]);
146 	free(names);
147 	closedir(dirp);
148 	return (-1);
149 }
150 
151 int
152 select_non_dot(const struct dirent *d)
153 {
154 	return strcmp(d->d_name, ".");
155 }
156 
157 int
158 select_non_dotdot(const struct dirent *d)
159 {
160 	return strcmp(d->d_name, ".") && strcmp(d->d_name, "..");
161 }