GETDIRENTRIES(2) BSD System Calls Manual GETDIRENTRIES(2)
getdirentries -- get directory entries in a filesystem independent format
getdirentries(int fd, char *buf, int nbytes, long *basep);
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
u_int32_t d_fileno; /* file number of entry */
u_int16_t d_reclen; /* length of this record */
u_int8_t d_type; /* file type, see below */
u_int8_t d_namlen; /* length of string in d_name */
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. Users of
getdirentries() should skip entries with d_fileno = 0, as such entries represent files which
have been deleted but not yet removed from the directory entry. 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 excluding the null byte.
Thus the actual size of d_name may vary from 1 to MAXNAMELEN + 1. d_type is a integer rep-
resenting the type of the directory entry. The following types are defined in
#define DT_UNKNOWN 0
#define DT_FIFO 1
#define DT_CHR 2
#define DT_DIR 4
#define DT_BLK 6
#define DT_REG 8
#define DT_LNK 10
#define DT_SOCK 12
#define DT_WHT 14
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 cur-
rent 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.
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.
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.
The getdirentries() function first appeared in 4.4BSD.
BSD June 9, 1993 BSD