aboutsummaryrefslogtreecommitdiffhomepage
path: root/osdep/scandir.c
blob: 4d2e7556c3976ed56fbf75d731a2dbc836fe9da5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
/*
 * scandir, alphasort - scan a directory
 *
 * implementation for systems that do not have it in libc
 */

#include "config.h"

#include <sys/types.h>
#include <dirent.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>

/*
 * convenience helper function for scandir's |compar()| function: 
 * sort directory entries using strcoll(3)
 */
int
alphasort(const void *_a, const void *_b)
{
    struct dirent **a = (struct dirent **)_a;
    struct dirent **b = (struct dirent **)_b;
    return strcoll((*a)->d_name, (*b)->d_name);
}


#define strverscmp(a,b) strcoll(a,b) /* for now */

/*
 * convenience helper function for scandir's |compar()| function: 
 * sort directory entries using GNU |strverscmp()|
 */
int
versionsort(const void *_a, const void *_b)
{
    struct dirent **a = (struct dirent **)_a;
    struct dirent **b = (struct dirent **)_b;
    return strverscmp((*a)->d_name, (*b)->d_name);
}

/*
 * The scandir() function reads the directory dirname and builds an
 * array of pointers to directory entries using malloc(3).  It returns
 * the number of entries in the array.  A pointer to the array of
 * directory entries is stored in the location referenced by namelist.
 *
 * The select parameter is a pointer to a user supplied subroutine
 * which is called by scandir() to select which entries are to be
 * included in the array.  The select routine is passed a pointer to
 * a directory entry and should return a non-zero value if the
 * directory entry is to be included in the array.  If select is null,
 * then all the directory entries will be included.
 *
 * The compar parameter is a pointer to a user supplied subroutine
 * which is passed to qsort(3) to sort the completed array.  If this
 * pointer is null, the array is not sorted.
 */
int
scandir(const char *dirname,
	struct dirent ***ret_namelist,
	int (*select)(const struct dirent *),
	int (*compar)(const struct dirent **, const struct dirent **))
{
    int i, len;
    int used, allocated;
    DIR *dir;
    struct dirent *ent, *ent2;
    struct dirent **namelist = NULL;

    if ((dir = opendir(dirname)) == NULL)
	return -1;

    used = 0;
    allocated = 2;
    namelist = malloc(allocated * sizeof(struct dirent *));
    if (!namelist)
	goto error;

    while ((ent = readdir(dir)) != NULL) {

	if (select != NULL && !select(ent))
	    continue;

	/* duplicate struct direct for this entry */
	len = offsetof(struct dirent, d_name) + strlen(ent->d_name) + 1;
	if ((ent2 = malloc(len)) == NULL)
	    goto error;
	
	if (used >= allocated) {
	    allocated *= 2;
	    namelist = realloc(namelist, allocated * sizeof(struct dirent *));
	    if (!namelist)
		goto error;
	}
	memcpy(ent2, ent, len);
	namelist[used++] = ent2;
    }
    closedir(dir);

    if (compar)
	qsort(namelist, used, sizeof(struct dirent *),
	      (int (*)(const void *, const void *)) compar);

    *ret_namelist = namelist;
    return used;


error:
    closedir(dir);

    if (namelist) {
	for (i = 0; i < used; i++) 
	    free(namelist[i]);
	free(namelist);
    }
    return -1;
}


#if	STANDALONE_MAIN
int
main(int argc, char **argv)
{
	struct dirent **namelist;
	int i, n;

	n = scandir("/etc", &namelist, NULL, alphasort);

	for (i = 0; i < n; i++)
		printf("%s\n", namelist[i]->d_name);
}
#endif