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    The following form allows you to view linux man pages.

    Command:

    getdents

    
    
    

    SYNOPSIS

           int getdents(unsigned int fd, struct linux_dirent *dirp,
                        unsigned int count);
    
           Note: There is no glibc wrapper for this system call; see NOTES.
    
    
    

    DESCRIPTION

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

    ERRORS

           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.
    
           ENOTDIR
                  File descriptor does not refer to a directory.
    
    
    

    CONFORMING TO

           SVr4.
    
    
    

    NOTES

           Glibc  does  not  provide a wrapper for this system call; call it using
           syscall(2).  You will need to define the linux_dirent  structure  your-
           self.  However, you probably want to use readdir(3) instead.
    
           This call supersedes readdir(2).
    
           The original Linux getdents() system call did not handle large filesys-
           tems and large  file  offsets.   Consequently,  Linux  2.4  added  get-
           dents64(),  with wider types for the d_ino and d_off fields employed in
           the linux_dirent structure.
    
    
    

    EXAMPLE

           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 ---------------
               i-node#  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>
           };
    
           #define BUF_SIZE 1024
    
           int
           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)
                   handle_error("open");
    
               for ( ; ; ) {
                   nread = syscall(SYS_getdents, fd, buf, BUF_SIZE);
                   if (nread == -1)
                       handle_error("getdents");
    
                   if (nread == 0)
                       break;
    
                   printf("--------------- nread=%d ---------------\n", nread);
                   printf("i-node#  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;
                   }
               }
    
               exit(EXIT_SUCCESS);
           }
    
    
    

    SEE ALSO

           readdir(2), readdir(3)
    
    
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