getdents(2)                   System Calls Manual                  getdents(2)

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       getdents, getdents64 - <?><?><?><?><?><?><?><?><?><?>
       <?><?><?><?><?><?> <?><?><?><?><?><?><?><?>

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       <?><?><?><?><?> C (libc, -lc)

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       #include <sys/syscall.h>      /* <?><?><?><?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?><?> SYS_* */
       #include <unistd.h>

       long syscall(SYS_getdents, unsigned int fd, struct linux_dirent *dirp,
                    unsigned int count);

       #define _GNU_SOURCE             /* <?><?><?><?><?><?><?><?> feature_test_macros(7) */
       #include <dirent.h>

       ssize_t getdents64(int fd, void dirp[.count], size_t count);

       Note: glibc provides no wrapper for getdents(), necessitating the use
       of syscall(2).

       Note: There is no definition of struct linux_dirent in glibc; see
       NOTES.

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       <?><?><?><?><?><?><?><?><?> POSIX. <?> <?><?><?><?>
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       <?><?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?> <?><?><?><?>.

   getdents()
       <?><?><?><?><?><?><?><?><?> <?><?><?><?><?> getdents()
       <?><?><?><?><?><?> <?><?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?><?>
       linux_dirent <?><?> <?><?><?><?><?><?><?><?>, <?><?>
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       <?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?><?>
       <?><?><?><?><?><?><?><?><?><?> fd, <?> <?><?><?><?><?>,
       <?><?><?><?><?><?><?><?><?> <?> dirp. <?> <?><?><?><?><?><?><?><?><?>
       count <?><?><?><?><?><?><?><?> <?><?><?><?><?><?> <?><?><?><?><?>
       <?><?><?><?><?><?>.

       <?><?><?><?><?><?><?><?><?> linux_dirent <?><?><?><?><?><?><?><?><?><?>
       <?><?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?>:

           struct linux_dirent {
               unsigned long  d_ino;     /* Inode number */
               unsigned long  d_off;     /* Not an offset; see below */
               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 a filesystem-specific value with no
       specific meaning to user space, though on older filesystems it used to
       be the distance from the start of the directory to the start of the
       next linux_dirent; see readdir(3). d_reclen is the size of this entire
       linux_dirent.  d_name is a null-terminated filename.

       d_type -- <?><?><?><?> <?> <?><?><?><?><?> <?><?><?><?><?><?><?><?><?>,
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       <?><?><?><?><?><?><?><?> (<?><?><?><?><?><?><?><?><?><?><?><?> <?>
       <dirent.h>):

       DT_BLK      <?><?><?><?><?><?><?> <?><?><?><?><?><?><?><?><?><?>

       DT_CHR      <?><?><?><?><?><?><?><?><?><?>
                   <?><?><?><?><?><?><?><?><?><?>

       DT_DIR      <?><?><?><?><?><?><?>

       DT_FIFO     <?><?><?><?><?><?><?><?><?><?><?> <?><?><?><?><?> (FIFO)

       DT_LNK      <?><?><?><?><?><?><?><?><?><?><?><?><?> <?><?><?><?><?><?>

       DT_REG      <?><?><?><?><?><?><?> <?><?><?><?>

       DT_SOCK     <?><?><?><?><?><?><?><?> <?><?><?><?><?> UNIX

       DT_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 Linux 2.6.3,
       attempting to access this field always provides the value 0
       (DT_UNKNOWN).

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       <?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?> (<?><?><?><?><?>
       <?><?><?><?><?><?><?>: Btrfs, ext2, ext3 <?> ext4)
       <?><?><?><?><?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?> <?><?><?><?>
       <?><?><?><?><?> <?> d_type. <?><?><?> <?><?><?><?><?><?><?><?><?><?>
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       DT_UNKNOWN.

   getdents64()
       <?><?><?><?><?><?><?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?><?><?>
       <?><?><?><?><?> Linux getdents() <?><?> <?><?><?><?><?><?><?> <?>
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       <?><?><?><?> <?><?><?><?><?><?><?><?> getdents64(), <?> <?><?><?><?><?>
       <?><?><?><?><?><?><?><?> <?><?><?><?><?><?> <?><?><?><?><?> d_ino <?>
       d_off. <?><?><?><?><?> getdents64()
       <?><?><?><?><?><?><?><?><?><?><?><?> <?><?><?><?>
       <?><?><?><?><?><?><?><?><?> <?><?><?><?> d_type.

       <?><?><?><?><?><?><?><?><?> <?><?><?><?><?> getdents64()
       <?><?><?><?><?><?><?> getdents(), <?><?>
       <?><?><?><?><?><?><?><?><?><?><?> <?><?><?><?>, <?><?><?>
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       <?><?><?><?><?><?><?><?><?><?> <?><?><?><?>:

           struct linux_dirent64 {
               ino64_t        d_ino;    /* 64-bit inode number */
               off64_t        d_off;    /* Not an offset; see getdents() */
               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 to indicate
       the error.

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       EBADF  <?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?><?>
              <?><?><?><?><?><?><?><?><?><?> fd.

       EFAULT <?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?><?><?> <?><?>
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              <?><?><?><?><?><?><?> <?><?><?>.

       ENOENT <?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?> <?><?>
              <?><?><?><?><?><?><?><?><?><?>.

       ENOTDIR
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       SVr4.

       getdents64()
              glibc 2.30.

<?><?><?><?><?><?><?><?><?><?>
       glibc does not provide a wrapper for getdents(); call getdents() using
       syscall(2).  In that case you will need to define the linux_dirent or
       linux_dirent64 structure yourself.

       Probably, you want to use readdir(3)  instead of these system calls.

       <?><?><?><?><?><?> <?><?><?><?><?><?><?><?><?> <?><?><?><?><?><?>
       <?><?><?><?><?><?><?><?> readdir(2).

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       <?><?><?><?><?><?><?><?><?><?><?><?><?> getdents(). <?>
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       <?><?><?><?><?><?><?><?><?> <?> <?><?><?><?><?><?><?><?><?> <?> ext2:

           $ ./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

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

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

       #define BUF_SIZE 1024

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

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

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

               if (nread == 0)
                   break;

               printf("--------------- nread=%ld ---------------\n", nread);
               printf("inode#    file type  d_reclen  d_off   d_name\n");
               for (size_t bpos = 0; bpos < nread;) {
                   d = (struct linux_dirent *) (buf + bpos);
                   printf("%8lu  ", 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 %10jd  %s\n", d->d_reclen,
                          (intmax_t) d->d_off, d->d_name);
                   bpos += d->d_reclen;
               }
           }

           exit(EXIT_SUCCESS);
       }

<?><?><?><?><?><?><?><?> <?><?><?><?><?>
       readdir(2), readdir(3), inode(7)

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       <?><?><?><?><?><?><?><?><?><?>(<?>) Azamat Hackimov
       <azamat.hackimov@gmail.com>, Dmitry Bolkhovskikh <d20052005@yandex.ru>,
       Vladislav <ivladislavefimov@gmail.com>, Yuri Kozlov
       <yuray@komyakino.ru>, <?><?><?><?> <?><?><?><?><?><?>
       <pavia00@gmail.com> <?> Kirill Rekhov <krekhov.dev@gmail.com>

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       <?><?><?><?><?><?><?><?> GNU (GNU General Public License - GPL,
       <https://www.gnu.org/licenses/gpl-3.0.html> <?><?><?><?><?><?> 3
       <?><?><?> <?><?><?><?><?> <?><?><?><?><?><?><?>) <?>
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       <?><?><?><?><?><?><?><?><?><?><?><?>
       <<debian-l10n-russian@lists.debian.org>>.

<?><?><?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?><?> Linux 6.9.1
                           15 <?><?><?><?> 2024 <?>.               getdents(2)