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questions on chdir

Hi all,
can someone lead me on how should i use this chdir func properly in this prog...
the chdir func that i've to use here is for two reasons
1)is to switch to a new directory if the sub directory is found as a directory not file (not sure where and what i should edit my codes)
2)switch back up to the parent directory (this one i put before the end of while loop)

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <limits.h>

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

unsigned process_directory( char *theDir )
{
    	DIR *dir = NULL;
    	struct dirent entry;
    	struct dirent *retval = 0;
    	unsigned count = 0;
	char pathName[PATH_MAX + 1];

    	/* Open the given directory, if you can. */  
    	dir = opendir( theDir );
    	if( dir == NULL ) 
	{
        	printf( "Error opening %s: %s", theDir, strerror( errno ) );
        	return 0;
    	}
	
	retval = readdir_r( dir, &entry);
    	while( retval != NULL ) 
	{
        	struct stat entryInfo;
        
        	if( ( strncmp( entry.d_name, ".", PATH_MAX ) == 0 ) || ( strncmp( entry.d_name, "..", PATH_MAX ) == 0 ) ) 
		{
            		/* Short-circuit the . and .. entries. */
            		retval = readdir_r( dir, &entry);
            		continue;
        	}
		(void)strncpy( pathName, theDir, PATH_MAX );
        	(void)strncat( pathName, "/", PATH_MAX );
        	(void)strncat( pathName, entry.d_name, PATH_MAX );
        
        	if( lstat( pathName, &entryInfo ) == 0 ) 
		{
            		/* stat() succeeded, let's party */
            		count++;
            
            		if( S_ISDIR( entryInfo.st_mode ) ) 
			{            
				/* directory */
                		printf( "processing %s/\n", pathName );
                		count += process_directory( pathName );
            		} 
			else if( S_ISREG( entryInfo.st_mode ) ) 
			{ 
				/* regular file */
                		printf( "\t%s has %lld bytes\n", pathName, (long long)entryInfo.st_size );
            		} 
			else if( S_ISLNK( entryInfo.st_mode ) ) 
			{ 
				/* symbolic link */
                		char targetName[PATH_MAX + 1];
                		if( readlink( pathName, targetName, PATH_MAX ) != -1 ) 
				{
                    			printf( "\t%s -> %s\n", pathName, targetName );
                		} 
				else 
				{
                    			printf( "\t%s -> (invalid symbolic link!)\n", pathName );
                		}
            		}
        	} 
		else 
		{
            		printf( "Error statting %s: %s\n", pathName, strerror( errno ) );
        	}
 		retval = readdir_r( dir, &entry);
		/* Switch up to parent directory
		   Now that all directories at this level have been processed*/
		chdir(".."); 
    	}
    
    	/* Close the directory and return the number of entries. */
    	(void)closedir( dir );
    	return count;
}

/* readdir_demo main()
 * 
 * Run through the specified directories, and pass them
 * to process_directory().
 */
int main( int argc, char **argv )
{
    int idx = 0;
    unsigned count = 0;
    
    for( idx = 1; idx < argc; idx++ ) {
        count += process_directory( argv[idx] );
    }
    
    return EXIT_SUCCESS;
}

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with the chdir func i got error msg:

cpfoo@csa02 ~$ gcc as3.c -o MY
cpfoo@csa02 ~$ MY CS224
processing CS224/as3/
      CS224/as3/ourhdr.h has 4128 bytes
Error statting CS224/as3/MY: No such file or directory
Error statting CS224/as3/error.c: No such file or directory
Error statting CS224/as3/a.out: No such file or directory
Error statting CS224/as3/as3.c: No such file or directory
Error statting CS224/as1: No such file or directory
Error statting CS224/.deps: No such file or directory
Error statting CS224/test: No such file or directory
Error statting CS224/as2: No such file or directory

without the chdir:

cpfoo@csa02 ~$ gcc as3.c -o MY
cpfoo@csa02 ~$ MY CS224
processing CS224/as3/
      CS224/as3/ourhdr.h has 4128 bytes
      CS224/as3/error.c has 1837 bytes
      CS224/as3/as3.c has 2887 bytes
processing CS224/as1/
      CS224/as1/stamp-h1 has 23 bytes
      CS224/as1/configure has 137161 bytes
      CS224/as1/cpwh.c has 3503 bytes
      CS224/as1/missing has 11492 bytes
      CS224/as1/error.o has 5604 bytes
      CS224/as1/config.h.in has 625 bytes
Segmentation Fault (core dumped)

any help will be greatly appreciated:)

Narendra Kumar S S

Your program is visiting all the directories recursively and lists all the files.
In this, you don't need to do chdir().
Actually you are not entering any directory here.
You are just reading the directories just like file.
If the entry inside the directory is again another directory, you will recursively call the function.
If it is a link, follow the target and if it is a regular, file print its name.
So, why do you want to do chdir().
The chdir() will change your pwd for the running program, that's all.