scandir.3

汇编源代码大全

.TH SCANDIR 3
.\" $Header: scandir.3,v 1.1 87/12/29 21:35:54 rsalz Exp $
.SH NAME
scandir, alphasort \- scan a directory
.SH SYNOPSIS
.nf
.ft B
#include <sys/types.h>
#include <sys/dirent.h>

int
scandir(name, list, selector, sorter)
.in +4n
char *name;
struct dirent ***list;
int (*selector)();
int (*sorter)();
.in -4n

int
alphasort(d1, d2)
.in +4n
struct dirent **d1;
struct dirent **d2;
.in -4n
.ft R
.fi
.SH DESCRIPTION
.I Scandir
reads the directory
.I name
and builds a NULL\-terminated array of pointers to the entries found
in that directory.
This array is put into the location pointed to by the
.I list
parameter.
.PP
If the
.I selector
parameter is non\-NULL, it is taken to be a pointer to a function called
with each entry, to determine whether or not it should be included in
the returned list.
If the parameter is NULL, all entries are included.
.PP
As an added feature, the entries can be sorted (with
.IR qsort (3))
before the list is returned.
If the
.I sorter
parameter is non\-NULL, it is passed to qsort to use as the comparison
function.
The
.I alphasort
routine is provided to sort the array alphabetically.
.PP
The array pointed to by
.I list
and the items it points to are all space obtained through
.IR malloc (3),
and their storage can be reclaimed as shown in the example below.
.SH "EXAMPLE"
Here is a small
.IR ls (1)\-like
program:
.ne 50
.RS
.nf
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/dir.h>

extern int alphasort();

static int
filesonly(e)
	struct dirent *e;
{
	struct stat sb;

	return(stat(e->d_name, &sb) >= 0 && (sb.st_mode & S_IFMT) == S_IFREG);
}

main(ac, av)
	int ac;
	char *av[];
{
	register int i;
	register int j;
	struct dirent **list;

	if (ac != 2) {
		fprintf(stderr, "usage: %s dirname\n", av[0]);
		exit(1);
	}
	if (chdir(av[1]) < 0) {
		perror(av[1]);
		exit(1);
	}
	if ((i = scandir(".", &list, filesonly, alphasort)) < 0) {
		perror("Error reading directory");
		exit(1);
	}
	for (j = 0; j < i; j++)
		printf("%s\n", list[j]->d_name);
	for (j = 0; j < i; j++)
		free((char *)list[j]);
	free((char *)list);
	exit(0);
}
.fi
.RE
.SH "SEE ALSO"
directory(3), qsort(3)
.SH DIAGNOSTICS
Returns the number of entries in the ``list,'' or \-1 if the directory
could not be opened or a memory allocation failed.
.SH BUGS
The routine can be slightly wasteful of space.