xref: /freebsd/lib/libc/gen/scandir.c (revision 1e413cf93298b5b97441a21d9a50fdcd0ee9945e)
1 /*
2  * Copyright (c) 1983, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 4. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 #if defined(LIBC_SCCS) && !defined(lint)
31 static char sccsid[] = "@(#)scandir.c	8.3 (Berkeley) 1/2/94";
32 #endif /* LIBC_SCCS and not lint */
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD$");
35 
36 /*
37  * Scan the directory dirname calling select to make a list of selected
38  * directory entries then sort using qsort and compare routine dcomp.
39  * Returns the number of entries and a pointer to a list of pointers to
40  * struct dirent (through namelist). Returns -1 if there were any errors.
41  */
42 
43 #include "namespace.h"
44 #include <sys/types.h>
45 #include <sys/stat.h>
46 #include <dirent.h>
47 #include <stdlib.h>
48 #include <string.h>
49 #include "un-namespace.h"
50 
51 /*
52  * The DIRSIZ macro is the minimum record length which will hold the directory
53  * entry.  This requires the amount of space in struct dirent without the
54  * d_name field, plus enough space for the name and a terminating nul byte
55  * (dp->d_namlen + 1), rounded up to a 4 byte boundary.
56  */
57 #undef DIRSIZ
58 #define DIRSIZ(dp)							\
59 	((sizeof(struct dirent) - sizeof(dp)->d_name) +			\
60 	    (((dp)->d_namlen + 1 + 3) &~ 3))
61 
62 int
63 scandir(dirname, namelist, select, dcomp)
64 	const char *dirname;
65 	struct dirent ***namelist;
66 	int (*select)(struct dirent *);
67 	int (*dcomp)(const void *, const void *);
68 {
69 	struct dirent *d, *p, **names = NULL;
70 	size_t nitems = 0;
71 	struct stat stb;
72 	long arraysz;
73 	DIR *dirp;
74 
75 	if ((dirp = opendir(dirname)) == NULL)
76 		return(-1);
77 	if (_fstat(dirp->dd_fd, &stb) < 0)
78 		goto fail;
79 
80 	/*
81 	 * estimate the array size by taking the size of the directory file
82 	 * and dividing it by a multiple of the minimum size entry.
83 	 */
84 	arraysz = (stb.st_size / 24);
85 	names = (struct dirent **)malloc(arraysz * sizeof(struct dirent *));
86 	if (names == NULL)
87 		goto fail;
88 
89 	while ((d = readdir(dirp)) != NULL) {
90 		if (select != NULL && !(*select)(d))
91 			continue;	/* just selected names */
92 		/*
93 		 * Make a minimum size copy of the data
94 		 */
95 		p = (struct dirent *)malloc(DIRSIZ(d));
96 		if (p == NULL)
97 			goto fail;
98 		p->d_fileno = d->d_fileno;
99 		p->d_type = d->d_type;
100 		p->d_reclen = d->d_reclen;
101 		p->d_namlen = d->d_namlen;
102 		bcopy(d->d_name, p->d_name, p->d_namlen + 1);
103 		/*
104 		 * Check to make sure the array has space left and
105 		 * realloc the maximum size.
106 		 */
107 		if (nitems >= arraysz) {
108 			const int inc = 10;	/* increase by this much */
109 			struct dirent **names2;
110 
111 			names2 = (struct dirent **)realloc((char *)names,
112 				(arraysz + inc) * sizeof(struct dirent *));
113 			if (names2 == NULL) {
114 				free(p);
115 				goto fail;
116 			}
117 			names = names2;
118 			arraysz += inc;
119 		}
120 		names[nitems++] = p;
121 	}
122 	closedir(dirp);
123 	if (nitems && dcomp != NULL)
124 		qsort(names, nitems, sizeof(struct dirent *), dcomp);
125 	*namelist = names;
126 	return(nitems);
127 
128 fail:
129 	while (nitems > 0)
130 		free(names[--nitems]);
131 	free(names);
132 	closedir(dirp);
133 	return -1;
134 }
135 
136 /*
137  * Alphabetic order comparison routine for those who want it.
138  */
139 int
140 alphasort(d1, d2)
141 	const void *d1;
142 	const void *d2;
143 {
144 	return(strcmp((*(struct dirent **)d1)->d_name,
145 	    (*(struct dirent **)d2)->d_name));
146 }
147