NAME

getdirentries — get directory entries in a filesystem independent format

SYNOPSIS

#include <dirent.h>

int
getdirentries(int fd, char *buf, int nbytes, long *basep);

DESCRIPTION

getdirentries() reads directory entries from the directory referenced by the file descriptor fd into the buffer pointed to by buf, in a filesystem independent format. Up to nbytes of data will be transferred. nbytes must be greater than or equal to the block size associated with the file, see stat(2). Some filesystems may not support getdirentries() with buffers smaller than this size.

The data in the buffer is a series of dirent structures each containing the following entries:

unsigned long	d_fileno; 
unsigned short	d_reclen; 
unsigned short	d_namlen; 
char    	d_name[MAXNAMELEN + 1]; /* see below */

The d_fileno entry is a number which is unique for each distinct file in the filesystem. Files that are linked by hard links (see link(2)) have the same d_fileno. If d_fileno is zero, the entry refers to a deleted file.

The d_reclen entry is the length, in bytes, of the directory record.

The d_namlen entry specifies the length of the file name excluding the null byte. Thus the actual size of d_name may vary from 1 to MAXNAMELEN + 1.

The d_name entry contains a null terminated file name.

Entries may be separated by extra space. The d_reclen entry may be used as an offset from the start of a dirent structure to the next structure, if any.

The actual number of bytes transferred is returned. The current position pointer associated with fd is set to point to the next block of entries. The pointer may not advance by the number of bytes returned by getdirentries(). A value of zero is returned when the end of the directory has been reached.

getdirentries() writes the position of the block read into the location pointed to by basep. Alternatively, the current position pointer may be set and retrieved by lseek(2). The current position pointer should only be set to a value returned by lseek(2), a value returned in the location pointed to by basep, or zero.

RETURN VALUES

If successful, the number of bytes actually transferred is returned. Otherwise, -1 is returned and the global variable errno is set to indicate the error.

ERRORS

getdirentries() will fail if:

[EBADF]

fd is not a valid file descriptor open for reading.

[EFAULT]

Either buf or basep point outside the allocated address space.

[EIO]

An I/O error occurred while reading from or writing to the file system.

SEE ALSO

lseek(2), open(2)

HISTORY

The getdirentries() function first appeared in 4.4BSD.