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getdirentries(2) [freebsd man page]

GETDIRENTRIES(2)					      BSD System Calls Manual						  GETDIRENTRIES(2)

NAME
getdirentries, getdents -- get directory entries in a file system independent format LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <sys/types.h> #include <dirent.h> int getdirentries(int fd, char *buf, int nbytes, long *basep); int getdents(int fd, char *buf, int nbytes); DESCRIPTION
The getdirentries() and getdents() system calls read directory entries from the directory referenced by the file descriptor fd into the buf- fer 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: uint32_t d_fileno; uint16_t d_reclen; uint8_t d_type; uint8_t d_namlen; char d_name[MAXNAMELEN + 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 MAXNAMELEN + 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 struc- ture, 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 getdirentries() or getdents(). A value of zero is returned when the end of the directory has been reached. 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 indi- cate the error. ERRORS
The getdirentries() system call will fail if: [EBADF] The fd argument is not a valid file descriptor open for reading. [EFAULT] Either buf or basep point outside the allocated address space. [EINVAL] 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. [EIO] An I/O error occurred while reading from or writing to the file system. SEE ALSO
lseek(2), open(2) HISTORY
The getdirentries() system call first appeared in 4.4BSD. The getdents() system call first appeared in FreeBSD 3.0. BSD
May 3, 1995 BSD

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getdirentries(2)						System Calls Manual						  getdirentries(2)

Name
       getdirentries - gets directory entries in a generic directory format

Syntax
       #include <sys/dir.h>

       cc = getdirentries(fd, buf, nbytes, basep)
       int cc, fd;
       char *buf;
       int nbytes;
       long *basep;

Description
       The  system  call  puts	directory  entries from the directory referenced by the file descriptor fd into the buffer pointed to by buf, in a
       generic directory format.  Up to nbytes of data are transferred.  The nbytes of data must be greater than or equal to the block size  asso-
       ciated with the file.  For further information, see Sizes less than nbytes can cause errors on certain file systems.

       The data returned in the buffer is a series of direct structures, each containing the following entries:
       unsigned long   d_ino;
       unsigned short  d_reclen;
       unsigned short  d_namlen;
       char	       d_name[MAXNAMLEN + 1];

       The  d_ino  entry  is a number that is unique for each distinct file in the file system.  Files that are linked by hard links have the same
       d_ino .	For further information, see The d_reclen entry is the length, in bytes, of the directory record.  The	d_namlen  entry  specifies
       the  length  of	the file name.	The d_name entry contains a null-terminated file name.	Thus, the actual size of d_name can vary from 2 to
       MAXNAMLEN + 1.

       The generic directory structures are not necessarily tightly packed.  The d_reclen entry may be used as an offset from the beginning  of  a
       direct structure to the next structure, if any.

       Upon  return,  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 is not necessarily incremented by the number of bytes returned by If the value returned  is	zero,  the
       end of the directory has been reached.  The current position pointer may be set and retrieved by The system call writes the position of the
       block read into the location pointed to by basep.  It is not safe to set the current position pointer to any value other than a value  pre-
       viously returned by or a value previously returned in the location pointed to by basep or zero.

Return Values
       If  successful,	the number of bytes actually transferred is returned.  Otherwise, a -1 is returned and the global variable errno is set to
       indicate the error.

Diagnostics
       The system call fails under the following conditions:

       EBADF	      The fd is not a valid file descriptor open for reading.

       ENOTDIR	      The fd is not a directory.

       EFAULT	      Either buf or basep points outside the allocated address space.

       EIO	      While reading from or writing to the file system, an I/O error occurred.

       EINTR	      A read from a slow device was interrupted by the delivery of a signal before any data arrived.

       EPERM	      The user does not have read permission in the directory.	The system call is not the suggested interface for reading  direc-
		      tories.  The and routines offer a standard interface. See the reference page for information on these routines.

See Also
       close(2), link(2), lseek(2), open(2), stat(2), directory(3)

																  getdirentries(2)

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