|GETDIRENTRIES(2)||System Calls Manual||GETDIRENTRIES(2)|
getdents — get directory
entries in a file system independent format
Standard C Library (libc, -lc)
fd, char *buf,
fd, char *buf,
system calls read directory entries from the directory referenced by the
file descriptor fd into the buffer pointed to by
buf, in a file system independent format. Up to
nbytes of data will be transferred. The
nbytes argument must be greater than or equal to the
block size associated with the file, see stat(2). Some
file systems may not support these system calls with buffers smaller than
The data in the buffer is a series of dirent structures each containing the following entries:
ino_t d_fileno; off_t d_off; uint16_t d_reclen; uint8_t d_type; uint16_t d_namlen; char d_name[MAXNAMLEN + 1]; /* see below */
The d_fileno entry is a number which is
unique for each distinct file in the file system. Files that are linked by
hard links (see link(2)) have the same
d_fileno. The d_off field
returns a cookie which can be used with lseek(2) to
position the directory descriptor to the next entry. The
d_reclen entry is the length, in bytes, of the
directory record. The d_type entry is the type of the
file pointed to by the directory record. The file type values are defined in
<sys/dirent.h>. 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
MAXNAMLEN + 1.
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
If the basep pointer
value is non-NULL , the
system call 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
a value returned in the d_off field, or zero.
The d_off field is being used as a cookie to readdir for nfs servers. These cookies can be cached and allow to read directory entries at a specific offset on demand.
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() system call will fail
- The fd argument is not a valid file descriptor open for reading.
- Either buf or non-NULL basep point outside the allocated address space.
- The file referenced by fd is not a directory, or nbytes is too small for returning a directory entry or block of entries, or the current position pointer is invalid.
- An I/O error occurred while reading from or writing to the file system.
- Corrupted data was detected while reading from the file system.
getdirentries() system call first
appeared in 4.4BSD. The
getdents() system call first appeared in
|March 30, 2020||Debian|