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       getdents, getdents64 - get directory entries


       int getdents(unsigned int fd, struct linux_dirent *dirp,
                    unsigned int count);
       int getdents64(unsigned int fd, struct linux_dirent64 *dirp,
                    unsigned int count);

       Note: There are no glibc wrappers for these system calls; see NOTES.


       These are not the interfaces you are interested in.  Look at readdir(3)
       for the POSIX-conforming C library interface.  This page documents  the
       bare kernel system call interfaces.

       The  system  call getdents() reads several linux_dirent structures from
       the directory referred to by the  open  file  descriptor  fd  into  the
       buffer  pointed  to  by dirp.  The argument count specifies the size of
       that buffer.

       The linux_dirent structure is declared as follows:

           struct linux_dirent {
               unsigned long  d_ino;     /* Inode number */
               unsigned long  d_off;     /* Offset to next linux_dirent */
               unsigned short d_reclen;  /* Length of this linux_dirent */
               char           d_name[];  /* Filename (null-terminated) */
                                 /* length is actually (d_reclen - 2 -
                                    offsetof(struct linux_dirent, d_name)) */
               char           pad;       // Zero padding byte
               char           d_type;    // File type (only since Linux
                                         // 2.6.4); offset is (d_reclen - 1)

       d_ino is an inode number.  d_off is the distance from the start of  the
       directory  to the start of the next linux_dirent.  d_reclen is the size
       of this entire linux_dirent.  d_name is a null-terminated filename.

       d_type is a byte at the end of the structure that  indicates  the  file
       type.  It contains one of the following values (defined in <dirent.h>):

       DT_BLK      This is a block device.

       DT_CHR      This is a character device.

       DT_DIR      This is a directory.

       DT_FIFO     This is a named pipe (FIFO).

       DT_LNK      This is a symbolic link.

       DT_REG      This is a regular file.

       DT_SOCK     This is a UNIX domain socket.

       DT_UNKNOWN  The file type is unknown.

       The d_type field is implemented since Linux 2.6.4.  It occupies a space
       that was previously a zero-filled  padding  byte  in  the  linux_dirent
       structure.   Thus,  on kernels up to and including 2.6.3, attempting to
       access this field always provides the value 0 (DT_UNKNOWN).

       Currently, only some filesystems (among them: Btrfs,  ext2,  ext3,  and
       ext4)  have  full  support  for returning the file type in d_type.  All
       applications must properly handle a return of DT_UNKNOWN.

       The  original  Linux  getdents()  system  call  did  not  handle  large
       filesystems  and  large  file  offsets.   Consequently, Linux 2.4 added
       getdents64(), with wider types for the  d_ino  and  d_off  fields.   In
       addition, getdents64() supports an explicit d_type field.

       The getdents64() system call is like getdents(), except that its second
       argument is  a  pointer  to  a  buffer  containing  structures  of  the
       following type:

           struct linux_dirent64 {
               ino64_t        d_ino;    /* 64-bit inode number */
               off64_t        d_off;    /* 64-bit offset to next structure */
               unsigned short d_reclen; /* Size of this dirent */
               unsigned char  d_type;   /* File type */
               char           d_name[]; /* Filename (null-terminated) */


       On success, the number of bytes read is returned.  On end of directory,
       0  is  returned.   On  error,  -1  is  returned,  and  errno   is   set


       EBADF  Invalid file descriptor fd.

       EFAULT Argument points outside the calling process's address space.

       EINVAL Result buffer is too small.

       ENOENT No such directory.

              File descriptor does not refer to a directory.




       Glibc  does  not  provide  a  wrapper for these system calls; call them
       using  syscall(2).   You  will  need  to  define  the  linux_dirent  or
       linux_dirent64  structure  yourself.  However, you probably want to use
       readdir(3) instead.

       These calls supersede readdir(2).


       The program below demonstrates the use of  getdents().   The  following
       output  shows an example of what we see when running this program on an
       ext2 directory:

           $ ./a.out /testfs/
           --------------- nread=120 ---------------
           inode#    file type  d_reclen  d_off   d_name
                  2  directory    16         12  .
                  2  directory    16         24  ..
                 11  directory    24         44  lost+found
                 12  regular      16         56  a
             228929  directory    16         68  sub
              16353  directory    16         80  sub2
             130817  directory    16       4096  sub3

   Program source

       #define _GNU_SOURCE
       #include <dirent.h>     /* Defines DT_* constants */
       #include <fcntl.h>
       #include <stdio.h>
       #include <unistd.h>
       #include <stdlib.h>
       #include <sys/stat.h>
       #include <sys/syscall.h>

       #define handle_error(msg) \
               do { perror(msg); exit(EXIT_FAILURE); } while (0)

       struct linux_dirent {
           long           d_ino;
           off_t          d_off;
           unsigned short d_reclen;
           char           d_name[];

       #define BUF_SIZE 1024

       main(int argc, char *argv[])
           int fd, nread;
           char buf[BUF_SIZE];
           struct linux_dirent *d;
           int bpos;
           char d_type;

           fd = open(argc > 1 ? argv[1] : ".", O_RDONLY | O_DIRECTORY);
           if (fd == -1)

           for ( ; ; ) {
               nread = syscall(SYS_getdents, fd, buf, BUF_SIZE);
               if (nread == -1)

               if (nread == 0)

               printf("--------------- nread=%d ---------------\n", nread);
               printf("inode#    file type  d_reclen  d_off   d_name\n");
               for (bpos = 0; bpos < nread;) {
                   d = (struct linux_dirent *) (buf + bpos);
                   printf("%8ld  ", d->d_ino);
                   d_type = *(buf + bpos + d->d_reclen - 1);
                   printf("%-10s ", (d_type == DT_REG) ?  "regular" :
                                    (d_type == DT_DIR) ?  "directory" :
                                    (d_type == DT_FIFO) ? "FIFO" :
                                    (d_type == DT_SOCK) ? "socket" :
                                    (d_type == DT_LNK) ?  "symlink" :
                                    (d_type == DT_BLK) ?  "block dev" :
                                    (d_type == DT_CHR) ?  "char dev" : "???");
                   printf("%4d %10lld  %s\n", d->d_reclen,
                           (long long) d->d_off, d->d_name);
                   bpos += d->d_reclen;



       readdir(2), readdir(3)


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