opendir.c

T-kernel 的extension源代码

/*
 *----------------------------------------------------------------------
 *    T-Kernel / Standard Extension
 *
 *    Copyright (C) 2006 by Ken Sakamura. All rights reserved.
 *    T-Kernel / Standard Extension is distributed 
 *      under the T-License for T-Kernel / Standard Extension.
 *----------------------------------------------------------------------
 *
 *    Version:   1.00.00
 *    Released by T-Engine Forum(http://www.t-engine.org) at 2006/8/11.
 *
 *----------------------------------------------------------------------
 */

/*
 *	@(#)opendir.c (libg) 
 *
 *	Directory operation
 *
 *	Use "SEIO"
 */

#include <seio/dirent.h>
#include <seio/fcntl.h>
#include <seio/unistd.h>
#include <seio/sys/types.h>
#include <seio/sys/stat.h>
#include <stdlib.h>
#include <errno.h>

/*
 * Open directory
 *	Open the directory indicated by "path", and position it in the first directory entry.
 *	Return value   != "NULL" normal (return the access handle)
 *		        = "NULL" error (set "errno")
 */
DIR* opendir( const char *path )
{
	DIR		*dp;
	struct stat	stat;

	dp = calloc(1, sizeof(DIR));
	if ( dp == NULL ) {
		errno = ENOMEM;
		goto err_ret1;
	}

	/* Open the directory */
	dp->dd_fd = open(path, O_RDONLY);
	if ( dp->dd_fd < 0 ) {
		goto err_ret2;
	}

	/* Check the adequate size as a read buffer */
	if ( fstat(dp->dd_fd, &stat) < 0 ) {
		goto err_ret2;
	}

	/* Allocate a read buffer */
	dp->dd_len = (int)stat.st_blksize;
	dp->dd_buf = malloc((size_t)dp->dd_len);
	if ( dp->dd_buf == NULL ) {
		errno = ENOMEM;
		goto err_ret3;
	}

	dp->dd_size = 0;
	dp->dd_loc = 0;

	return dp;

err_ret3:
	(void)close(dp->dd_fd);
err_ret2:
	free(dp);
err_ret1:
	return NULL;
}

/*
 * Get directory entry
 *	Retrieve 1 directory entry, and advance the current position to the next.
 *	Return value  != "NULL" normal (the retrieved directory entry)
 *		       = "NULL" end or error (set "errno" when error occurs)
 */
struct dirent* readdir( DIR *dp )
{
	struct dirent	*dent;
	int		n;

	if ( dp->dd_loc >= dp->dd_size ) {
		/* Read into buffer */
		n = getdents(dp->dd_fd, (struct dirent*)dp->dd_buf,
						(size_t)dp->dd_len);
		if ( n <= 0 ) {
			/* Error or termination */
			return NULL;
		}
		dp->dd_size = n;
		dp->dd_loc = 0;
	}

	/* Directory entry of the current position */
	dent = (struct dirent*)(dp->dd_buf + dp->dd_loc);

	/* Advance the current position */
	dp->dd_loc += dent->d_reclen;

	return dent;
}

/*
 * Move to top
 *	Reset "dp" to point out the top of directory.
 *	By this setting, the directory becomes up-to-date,like the calling of "opendir() ". 
 */
void rewinddir( DIR *dp )
{
	(void)lseek(dp->dd_fd, 0L, SEEK_SET);

	dp->dd_size = 0;
	dp->dd_loc = 0;
}

/*
 * Close directory
 *	Return value      0    normal 
 *		  	 -1    error (set "errno")
 */
int closedir( DIR *dp )
{
	int		n;

	n = close(dp->dd_fd);
	free(dp->dd_buf);
	free(dp);

	return n;
}