getdirentriesget directory entries in a filesystem independent format

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

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

() 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 structures (see dir(5)) The order of the directory entries vended out via () is not specified. Some filesystems may return entries in lexicographic sort order and others may not.

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 () 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 representing the type of the directory entry. The following types are defined in ⟨sys/dirent.h⟩:

#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 (). A value of zero is returned when the end of the directory has been reached.

() 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.

getdirentries() should rarely be used directly; instead, opendir(3) and readdir(3) should be used.

As of Mac OS X 10.6, () is deprecated, and it is recommended that applications use readdir(3) rather than using getdirentries() directly. Due to limitations with the system call, getdirentries() will not work with 64-bit inodes; in order to use getdirentries(), _DARWIN_NO_64_BIT_INODE must be defined. See stat(2) for more information on _DARWIN_NO_64_BIT_INODE and its other effects.

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:

fd is not a valid file descriptor open for reading.
Either buf or basep point outside the allocated address space.
An I/O error occurred while reading from or writing to the file system.

lseek(2), open(2), stat(2), opendir(3), readdir(3), dir(5)

The getdirentries() function first appeared in 4.4BSD.

June 9, 1993 macOS 14.4