|GETDIRENTRIES(2)||System Calls Manual||GETDIRENTRIES(2)|
LIBRARY¶Standard C Library (libc, -lc)
fd, char *buf,
fd, char *buf,
getdents() 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 this size.
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_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
getdents(). A value of zero is returned when the end
of the directory has been reached.
If the basep pointer value is non-NULL , the
getdirentries() 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 basep
getdirentries() only) 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.
getdirentries() system call will fail if:
- 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.
SEE ALSO¶lseek(2), open(2)
getdirentries() system call first appeared in 4.4BSD. The
getdents() system call first appeared in FreeBSD 3.0.
|May 28, 2017||Linux 4.19.0-10-amd64|