getdents(2) - NetBSD Manual Pages

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GETDENTS(2)               NetBSD System Calls Manual               GETDENTS(2)


NAME
getdents -- get directory entries in a filesystem independent format
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <dirent.h> int getdents(int fd, char *buf, size_t nbytes);
DESCRIPTION
getdents() 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 getdents() with buffers smaller than this size. The data in the buffer is a series of dirent structures each containing the following entries: ino_t d_fileno; uint16_t d_reclen; uint16_t d_namlen; uint8_t d_type; char d_name[MAXNAMLEN + 1]; /* see below */ 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. If d_fileno is zero, the entry refers to a deleted file. The d_reclen entry is the length, in bytes, of the directory record. The d_type is the type of file, where the following are possible types: DT_UNKNOWN, DT_FIFO, DT_CHR, DT_DIR, DT_BLK, DT_REG, DT_LNK, DT_SOCK, and DT_WHT. 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 MAXNAMLEN + 1. The d_name entry contains a null terminated file name. 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 structure, 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 getdents(). A value of zero is returned when the end of the directory has been reached. 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), 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
getdents() will fail if: [EBADF] fd is not a valid file descriptor open for reading. [EFAULT] Either buf points outside the allocated address space. [EIO] An I/O error occurred while reading from or writing to the file system. [EINVAL] A directory was being read on NFS, but it was modified on the server while it was being read.
SEE ALSO
lseek(2), open(2), dirent(5)
HISTORY
The getdents() function first appeared in NetBSD 1.3. NetBSD 4.0 September 6, 2005 NetBSD 4.0
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