Linux and UNIX Man Pages

Test Your Knowledge in Computers #252
Difficulty: Easy
Network computer devices that originate, route and terminate the data are called server-only devices.
True or False?
Linux & Unix Commands - Search Man Pages

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

Check Out this Related Man Page

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

NAME
getdirentries -- get directory entries in a filesystem independent format SYNOPSIS
#include <dirent.h> #include <sys/types.h> #include <sys/dirent.h> int getdirentries(int fd, char *buf, int nbytes, long *basep); DESCRIPTION
getdirentries() reads directory entries from the directory referenced by the file descriptor fd into the buffer pointed to by buf, in a filesystem independent format. Up to nbytes of data will be transferred. Nbytes must be greater than or equal to the block size associated with the file, see stat(2). Some filesystems may not support getdirentries() with buffers smaller than this size. The data in the buffer is a series of dirent structures (see dir(5)) The order of the directory entries vended out via getdirentries() is not specified. Some filesystems may return entries in lexicographic sort order and others may not. The d_fileno entry is a number which is unique for each distinct file in the filesystem. Files that are linked by hard links (see link(2)) have the same d_fileno. Users of getdirentries() should skip entries with d_fileno = 0, as such entries represent files which have been deleted but not yet removed from the directory entry. The d_reclen entry is the length, in bytes, of the directory record. 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. d_type is a integer representing the type of the directory entry. The following types are defined in <sys/dirent.h>: #define DT_UNKNOWN 0 #define DT_FIFO 1 #define DT_CHR 2 #define DT_DIR 4 #define DT_BLK 6 #define DT_REG 8 #define DT_LNK 10 #define DT_SOCK 12 #define DT_WHT 14 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(). A value of zero is returned when the end of the directory has been reached. getdirentries() 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, or zero. NOTES
getdirentries() should rarely be used directly; instead, opendir(3) and readdir(3) should be used. As of Mac OS X 10.6, getdirentries() is deprecated, and it is recommended that applications use readdir(3) rather than using getdirentries() directly. Due to limitations with the system call, getdirentries() will not work with 64-bit inodes; in order to use getdirentries(), _DARWIN_NO_64_BIT_INODE must be defined. See stat(2) for more information on _DARWIN_NO_64_BIT_INODE and its other effects. 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
getdirentries() will fail if: [EBADF] fd is not a valid file descriptor open for reading. [EFAULT] Either buf or basep point outside the allocated address space. [EIO] An I/O error occurred while reading from or writing to the file system. SEE ALSO
lseek(2), open(2), stat(2), opendir(3), readdir(3), dir(5) HISTORY
The getdirentries() function first appeared in 4.4BSD. BSD
June 9, 1993 BSD

Featured Tech Videos