NAME

getdirentries − gets directory entries in a filesystem independent format

SYNOPSIS

#include <sys/dir.h>
cc = getdirentries(fd, buf, nbytes, basep)
int cc, fd;
char ∗buf;
int nbytes;
long ∗basep;

DESCRIPTION

Getdirentries attempts to put 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). Sizes less than this can cause errors on certain filesystems.

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

unsigned longd_fileno;
unsigned shortd_reclen;
unsigned shortd_namlen;
chard_name[MAXNAMELEN + 1];

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. The d_reclen entry is the length, in bytes, of the directory record.  The d_name entry contains a null terminated file name.  The d_namlen entry specifies the length of the file name.  Thus the actual size of d_name may vary from 2 to MAXNAMELEN + 1. 

The structures are not necessarily tightly packed.  The d_reclen entry may be used as an offset from the beginning of a direct structure to the next structure, if any. 

Upon return, 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 is not necessarily incremented by the number of bytes returned by getdirentries. If the value returned is zero, the end of the directory has been reached. The current position pointer may be set and retrieved by lseek(2). Getdirentries writes the position of the block read into the location pointed to by basep. It is not safe to set the current position pointer to any value other than a value previously returned by lseek(2) or a value previously returned in the location pointed to by basep or zero. 

RETURN VALUE

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

ERRORS

Getdirentries will fail if one or more of the following are true:

[EBADF] fd is not a valid file descriptor open for reading. 

[EFAULT] Either buf or basep point outside the allocated address space. 

[EINTR] A read from a slow device was interrupted before any data arrived by the delivery of a signal. 

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

SEE ALSO

lseek(2), open(2), stat(2)

4BSD