osdep/scandir.c

   1 /*
   2  * scandir, alphasort - scan a directory
   3  *
   4  * implementation for systems that do not have it in libc
   5  */
   6
   7 #include "config.h"
   8
   9 #ifndef HAVE_SCANDIR
  10
  11 #include <sys/types.h>
  12 #include <dirent.h>
  13 #include <stdlib.h>
  14 #include <stddef.h>
  15 #include <string.h>
  16
  17 /*
  18  * convenience helper function for scandir's |compar()| function:
  19  * sort directory entries using strcoll(3)
  20  */
  21 int
  22 alphasort(const void *_a, const void *_b)
  23 {
  24     struct dirent **a = (struct dirent **)_a;
  25     struct dirent **b = (struct dirent **)_b;
  26     return strcoll((*a)->d_name, (*b)->d_name);
  27 }
  28
  29
  30 #define strverscmp(a,b) strcoll(a,b) /* for now */
  31
  32 /*
  33  * convenience helper function for scandir's |compar()| function:
  34  * sort directory entries using GNU |strverscmp()|
  35  */
  36 int
  37 versionsort(const void *_a, const void *_b)
  38 {
  39     struct dirent **a = (struct dirent **)_a;
  40     struct dirent **b = (struct dirent **)_b;
  41     return strverscmp((*a)->d_name, (*b)->d_name);
  42 }
  43
  44 /*
  45  * The scandir() function reads the directory dirname and builds an
  46  * array of pointers to directory entries using malloc(3).  It returns
  47  * the number of entries in the array.  A pointer to the array of
  48  * directory entries is stored in the location referenced by namelist.
  49  *
  50  * The select parameter is a pointer to a user supplied subroutine
  51  * which is called by scandir() to select which entries are to be
  52  * included in the array.  The select routine is passed a pointer to
  53  * a directory entry and should return a non-zero value if the
  54  * directory entry is to be included in the array.  If select is null,
  55  * then all the directory entries will be included.
  56  *
  57  * The compar parameter is a pointer to a user supplied subroutine
  58  * which is passed to qsort(3) to sort the completed array.  If this
  59  * pointer is null, the array is not sorted.
  60  */
  61 int
  62 scandir(const char *dirname,
  63         struct dirent ***ret_namelist,
  64         int (*select)(const struct dirent *),
  65         int (*compar)(const struct dirent **, const struct dirent **))
  66 {
  67     int i, len;
  68     int used, allocated;
  69     DIR *dir;
  70     struct dirent *ent, *ent2;
  71     struct dirent **namelist = NULL;
  72
  73     if ((dir = opendir(dirname)) == NULL)
  74         return -1;
  75
  76     used = 0;
  77     allocated = 2;
  78     namelist = malloc(allocated * sizeof(struct dirent *));
  79     if (!namelist)
  80         goto error;
  81
  82     while ((ent = readdir(dir)) != NULL) {
  83
  84         if (select != NULL && !select(ent))
  85             continue;
  86
  87         /* duplicate struct direct for this entry */
  88         len = offsetof(struct dirent, d_name) + strlen(ent->d_name) + 1;
  89         if ((ent2 = malloc(len)) == NULL)
  90             goto error;
  91
  92         if (used >= allocated) {
  93             allocated *= 2;
  94             namelist = realloc(namelist, allocated * sizeof(struct dirent *));
  95             if (!namelist)
  96                 goto error;
  97         }
  98         memcpy(ent2, ent, len);
  99         namelist[used++] = ent2;
 100     }
 101     closedir(dir);
 102
 103     if (compar)
 104         qsort(namelist, used, sizeof(struct dirent *),
 105               (int (*)(const void *, const void *)) compar);
 106
 107     *ret_namelist = namelist;
 108     return used;
 109
 110
 111 error:
 112     closedir(dir);
 113
 114     if (namelist) {
 115         for (i = 0; i < used; i++)
 116             free(namelist[i]);
 117         free(namelist);
 118     }
 119     return -1;
 120 }
 121 #endif
 122
 123
 124 #if     STANDALONE_MAIN
 125 int
 126 main(int argc, char **argv)
 127 {
 128         struct dirent **namelist;
 129         int i, n;
 130
 131         n = scandir("/etc", &namelist, NULL, alphasort);
 132
 133         for (i = 0; i < n; i++)
 134                 printf("%s\n", namelist[i]->d_name);
 135 }
 136 #endif