scandir, alphasort - scan a directory

#include <sys/types.h>
#include <dirent.h>

scandir(dirname, namelist, select, compar)
const char *dirname;
struct dirent ***namelist;
int (*select)();
int (*compar)();

alphasort(d1, d2)
struct dirent **d1, **d2;

Scandir 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 and a pointer to the array through 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. Alphasort is a routine
which can be used for the compar parameter to sort the array

The memory allocated for the array can be deallocated with free
(see malloc(3)) by freeing each pointer in the array and the array

directory(3), malloc(3), qsort(3), dir(5)

Returns -1 if the directory cannot be opened for reading or if
malloc(3) cannot allocate enough memory to hold all the data