S_ISDIR not working as expected. what is going on?

zeppelin · 04-07-2004, 08:30 AM

hello. I'm not sure what is going on with the way I use S_ISDIR() macro.
Maybe you can help.

tree says

Quote:

[root@Freud DIR_TEST]# tree
.
|-- Anotherfile
|-- a_DIR
| `-- file_in_a_DIR
`-- a_file

1 directory, 3 files

but my compiled code says:

Quote:

$./foo DIR_TEST
. is a directory
.. is a directory
a_DIR is not a directory
a_file is not a directory
Anotherfile is not a directory

a_DIR is not detected as a DIRECTORY. what am I doing wrong?

this is my source code

Code:

#include <dirent.h>
#include <errno.h>
#include <stdio.h>
#include <time.h>
#include <sys/stat.h>
#include <unistd.h>

int scan_dir( char *_pathname );
int isdirectory(char *path);

int main(int argc, char **argv)
{
	if (argc != 2)
	{
		fprintf(stderr, "Usage: %s directory_name\n", argv[0]);
		return 1; 
	}
	scan_dir( argv[1] );
	
	
	
	return 0;
}

int scan_dir( char *path )
{
	struct dirent *direntp;
	DIR *dirp;
	
	if ((dirp = opendir(path)) == NULL)
	{
		perror ("Failed to open directory");
		return 1;
	}   
	
	while ((direntp = readdir(dirp)) != NULL)
	{
		if (isdirectory(direntp->d_name))
		{
			fprintf(stderr,"%s is a directory\n", direntp->d_name);
		}
   		else
      		fprintf(stderr,"%s is not a directory\n", direntp->d_name);
		
		//printf("%s\n", direntp->d_name);
	}
	
	while ((closedir(dirp) == -1) && (errno == EINTR)) ;
	
	return 0;
}


int isdirectory(char *path) {
   struct stat statbuf;

   if (stat(path, &statbuf) == -1)
      return 0;
   else
      return S_ISDIR(statbuf.st_mode);
}

thank you very much

zeppelin · 04-07-2004, 09:46 AM

SaTaN and others are welcomed to help :P

I mentioned SaTaN cause I did a lot of search in this forum before posting, and I saw that SaTaN {and not only} replies to similar to mine posts

jinksys · 04-08-2004, 11:17 PM

odd, compiled and ran just fine on my system. Could you post a `ls -l` of that directory¿?

zeppelin · 04-09-2004, 06:12 AM

ls -l DIR_TEST/
total 9
-rw-r--r-- 1 nk users 10 Apr 7 14:42 Anotherfile
drwxr-xr-x 2 nk users 48 Apr 8 22:47 aSecond_DIR
drwxr-xr-x 3 nk users 120 Apr 8 22:34 a_DIR
-rw-r--r-- 1 nk users 16 Apr 7 14:42 a_file

I found some stuff but I'm not sure.
it has to do with absolute path vs relative path.
can I use to all those functions [stat, readdir, opendir, chdir] the abs_path..?

I think that for some reason you have to chdir (new_dir) and then do that stat, readdir, opendir

I'm not sure, and man doesn't help. Anyone that is a C wizard can help me>><??..

kev82 · 04-09-2004, 08:23 AM

theres nothing wrong with S_ISDIR, because its working on . and .., im 99% sure the stat in is_directory is failing because of an invalid path(remember . and .. are valid paths, hence the stat works) - you should check this with a debugger or printf.

if im right then either pass an absolute path to stat or pass a "proper" relative path ie one that begins ./ or ../ if im not right then please post back with the return value from stat and the contents of statbuf.

zeppelin · 04-09-2004, 02:55 PM

hmm. the same relative_path thing [starting with ./] is also necessary for opendir() ??
chdir() needs it also?

I 'm more a basher where I just type cd NAME_OF_DIR and not cd ./NAME_OF_DIR

ps. the only way I debug is via printf().. ;(

The_Nerd · 04-10-2004, 11:52 AM

Use lstat instead:

Code:

DIR *tp;
struct dirent* pt;
struct stat st;

while((pt=readdir(tp))!=NULL) 
	{
		if (!strcmp(pt->d_name, ".")||!strcmp(pt->d_name, "..")) continue;
		strcpy(path, dir);
		if (path[strlen(path)-1]!='/') strcat(path, "/");
		strcat(path, pt->d_name);
		if (!(lstat(path, &st)>=0)) continue;
		if (st.st_mode&S_IFDIR)
                      //Is a folder
                  else if (st.st_mode&S_IFREG)
                      //File
          }

atamer · 04-17-2007, 05:42 PM

You are pretty right to make a confusion point between relative and absolute addresses
here is the working code for traversing a folder and print all sub - files/folders. Watch out ı used chdir. with out this system call stat S_ISFOLDER() make wrong decisions

tree_pointer traversaPath(char filename[]){

struct stat buf;
DIR *dirp;
struct dirent *dp;

if( (dirp = opendir(filename) ) == NULL ) {
printf("couldnt open %s\n",filename);
return;
}

do{
if(( dp = readdir(dirp)) != NULL){

lstat(dp->d_name, &buf);
if(S_ISDIR(buf.st_mode)){
if ( strcmp(dp->d_name, ".") != 0 && strcmp(dp->d_name, "..") != 0){

printf("directoryName %s\n",dp->d_name);
chdir(dp->d_name);

traversaPath(".");
chdir("../");
//printf("Dir\n");

printf("File Name :%s\n",dp->d_name);
}

}
else{

printf("File Name :%s\n",dp->d_name);
}

}while( dp != NULL );
closedir(dirp);
return NULL;

}

Hko · 04-19-2007, 10:21 AM

Quote:

Originally Posted by zeppelin

Code:

int isdirectory(char *path) {
   struct stat statbuf;

   if (stat(path, &statbuf) == -1)
      return 0;
   else
      return S_ISDIR(statbuf.st_mode);
}

If this function returns 0 it is pretty unclear whether an error ocuurred in stat(), or the path provided is not a directory!

One (simple) way to fix:

Code:

int isdirectory(char *path) {
   struct stat statbuf;

   if (stat(path, &statbuf) == -1) {
      perror("while calling stat()");
      return -1;
   } else {
      return S_ISDIR(statbuf.st_mode);
   }
}

also fix the calling code to check the return value for -1 (error).