Unix/Linux 获取文件系统目录的程序。附一篇。

代码：

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <dirent.h>
#include <limits.h>

/* function type that is called for each filename */
typedef int Myfunc(const char *,const struct stat *,int);
static	Myfunc	myfunc;
static	int		myftw(char *,Myfunc *);
static	int		dopath(Myfunc *);

static	long	nreg,ndir,nblk,nchr,nfifo,nslink,nsock,ntot;

int main(int argc,char **argv)
{
	int		ret;

	if(argc != 2){
		fprintf(stderr,"usage: ftw <starting-pathname>\n");
		exit(1);
	}

	ret = myftw(argv[1],myfunc);	/* does it all */

	ntot = nreg + ndir + nblk + nchr + nfile + nslink + nsock;
	if(ntot == 0)	/* aoid divide by 0;print 0 for all counts */
		ntot = 1;
	printf("regular files = %7ld, %5.2f %%\n",nreg,nreg*100.0/ntot);
	printf("directories = %7ld, %5.2f %%\n",ndir,ndir*100.0/ntot);
	printf("block special = %7ld, %5.2f %%\n",nblk,nblk*100.0/ntot);
	printf("char special = %7ld, %5.2f %%\n",nchr,nchr*100.0/ntot);
	printf("FIFOs	 = %7ld, %5.2f %%\n",nfifo,nfifo*100.0/ntot);
	printf("symbolic links = %7ld, %5.2f %%\n",nslink,nslink*100.0/ntot);
	printf("sockets		= %7ld, %5.2f %%\n",nsock,nsock*100.0/ntot);

	exit(ret);
}

/*
 *	Descend through the hierarchy,starting at "pathname".
 *	The Caller's func() is called for every file.
*/
#define	FTW_F	1	/* File oter than directory */
#define	FTW_D	2	/* Directory */
#define	FTW_DNR	3	/* Directory that can't be read */
#define	FTW_NS	4	/* File that we can't stat */

static char *fullpath;	/* contains full pathname for every file */

static int myftw(char *pathname,Myfunc *func)
{
	int		len;
	fullpath = path_alloc(&len);	/* malloc's for PATH_MAX+1 bytes */

	strncpy(fullpath,pathname,len);	/* protect against */
	fullpath[len-1] = 0;			/* buffer overrun */

	return(dopath(func));
}

/*
 *	Descend through the hierarchy,starting at "fullpath".
 *	If "fullpath" is anything other than a directory,we lstat() it,
 *	call func(),and return. For a directory,we call ourself
 *	recursvely for each name in the directory.
*/
static int dopath(Myfunc *func)	/* we return whatever func() returns */
{
	struct	stat	statbuf;
	struct	dirent	*dirp;
	DIR		*dp;
	int		ret;
	char	*ptr;

	if(lstat(fullpath,&statbuf) < 0)	/* stat error */
		return(func(fullpath,&statbuf,FTW_NS));
	if(S_ISDIR(statbuf.st_mode) == 0)	/* not a directory */
		return(func(fullpath,&statbuf,FTW_F));
	
	/*
	 *	It's a dircetory.	First call func() for the directory,
	 *	then process each filename in the directory.
	*/
	if((ret = func(fullpath,&statbuf,FTW_D)) != 0)
		return (ret);

	ptr = fullpath + strlen(fullpath);	/* point to end of fullpath */
	*ptr++ = '/';
	*ptr = 0;

	if((dp = opendir(fullpath)) == NULL)	/* can't read directory */
		return(func(fullpath,&statbuf,FTW_DNR));

	while((dirp = readdir(dp)) != NULL){
		if(strcmp(dirp->d_name,".") == 0 || strcmp(dirp->d_name,"..") == 0)	/* ignore dot and dot-dot */
			continue;

		strcpy(ptr,dirp->d_name);	/* append name after slash */

		if((ret = dopath(func)) != 0)	/* recursive */
			break;	/* time to leave */
	}
	ptr[-1] = 0;	/* erase everything from alash onwards */

	if(closedir(dp) < 0){
		fprintf(stderr,"Can't close directory %s",fullpath);
		exit(-1);
	}

	return (ret);
}

static	int	myfunc(const char *pathname,const struct stat *statptr,int type)
{
	switch(type){
		case FTW_F:
			switch(statptr->st_mode & S_IFMT){
				case S_IFREG:	
					nreg++;
					break;
				case S_IFBLK:
					nblk++;
					break;
				case S_IFCHR:
					nchr++;
					break;
				case S_IFIFO:
					nfifo++;
					break;
				case S_IFLNK:
					nslink++;
					break;
				case S_IFSOCK:
					nsock++;
					break;
				case S_IFDIR:
					fprintf(stderr,"for S_IFDIR for %s\n",pathname);	/* directories should have type = FTW_D */
			}
			case FTW_D:
				ndir++;
				break;
			case FTW_DNR:
				fprintf(stderr,"Can't read directory %s\n",pathname);
				break;
			case FTW_NS:
				fprintf(stderr,"stat error for %s\n",pathname);
				break;				
			default:
				fprintf(stderr,"unknown type %d for pathname %s",type,pathname);
		}

		return 0;
	}
}

另一種列出目錄的demo，比較簡單，如下：

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#include <dirent.h>

/*
 *  功能描述：
 *	根據用戶輸入的目錄來逐級打印目錄名字
*/
void printdir(char *dir,int depth)
{
	DIR *dp;
	struct dirent *entry;
	struct stat statbuf;

	if((dp = opendir(dir)) == NULL){
		fprintf(stderr,"Can't Open directory: %s\n",dir);
		return;
	}
	chdir(dir);
	while((entry = readdir(dp)) != NULL){
		lstat(entry->d_name,&statbuf);
		if(S_ISDIR(statbuf.st_mode)){
			/* Found a directory,but we should ignore . and .. */
			if(strcmp(".",entry->d_name) == 0 || strcmp("..",entry->d_name) == 0)
				continue;
			printf("%*s%s/\n",depth,"",entry->d_name);
			/* Recurse at a new indent level */
			printdir(entry->d_name,depth+4);
		}
		else
			printf("%*s%s\n",depth,"",entry->d_name);
	}
	chdir("..");	/* 返回上級目錄并關閉,可以看出,如果目錄深度很大的話, */
	closedir(dp);	/* 有可能會報錯,原因是單個進程所能打開的最大文件數 */
}

int main(int argc,char **argv)
{
	char *topdir=".";
	if(argc != 2){
		fprintf(stderr,"usage: ./a.out <pathname#>\n");
		exit(0);
	}
	topdir=argv[1];

	printf("Directory scan of %s:\n",topdir);
	printdir(topdir,0);
	printf("done.\n");

	exit(0);
}

其實這兩個例子的實質都是一樣的。