MirOS Manual: closedir(3), directory(3), dirfd(3), opendir(3), readdir(3), readdir_r(3), rewinddir(3), seekdir(3), telldir(3)

DIRECTORY(3)               BSD Programmer's Manual                DIRECTORY(3)

NAME

     opendir, readdir, readdir_r, telldir, seekdir, rewinddir, closedir, dirfd
     - directory operations

SYNOPSIS

     #include <sys/types.h>
     #include <dirent.h>

     DIR *
     opendir(const char *filename);

     struct dirent *
     readdir(DIR *dirp);

     int
     readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result);

     long
     telldir(const DIR *dirp);

     void
     seekdir(DIR *dirp, long loc);

     void
     rewinddir(DIR *dirp);

     int
     closedir(DIR *dirp);

     int
     dirfd(DIR *dirp);

DESCRIPTION

     The opendir() function opens the directory named by filename, associates
     a directory stream with it, and returns a pointer to be used to identify
     the directory stream in subsequent operations. A null pointer is returned
     if filename cannot be accessed, or if malloc(3) cannot allocate enough
     memory to hold the entire structure.

     The readdir() function returns a pointer to the next directory entry in
     the named directory stream dirp. It returns NULL upon reaching the end of
     the directory or detecting an invalid seekdir() operation.

     The readdir_r() function (much like readdir()) initializes the dirent
     structure referenced by entry to represent the next directory entry in
     the named directory stream dirp, and stores a pointer to this structure
     at the location referenced by result. The storage pointed to by entry
     must be large enough for a dirent with a d_name array member containing
     at least NAME_MAX plus one elements. On successful return, the pointer
     returned at *result will have the same value as the argument entry. Upon
     reaching the end of the directory stream, this pointer shall have the
     value NULL.

     The telldir() function returns the current location associated with the
     named directory stream dirp.

     The seekdir() function sets the position of the next readdir() operation
     on the named directory stream dirp. The new position reverts to the one
     associated with the directory stream when the telldir() operation was
     performed. Values returned by telldir() are good only for the lifetime of
     the DIR pointer, dirp, from which they are derived. If the directory is
     closed and then reopened, the telldir() value may be invalidated due to
     undetected directory compaction. It is safe to use a previous telldir()
     value immediately after a call to opendir() and before any calls to read-
     dir().

     The rewinddir() function resets the position of the named directory
     stream dirp to the beginning of the directory.

     The closedir() function closes the named directory stream and frees the
     structure associated with the dirp pointer, returning 0 on success. On
     failure, -1 is returned and the global variable errno is set to indicate
     the error.

     The dirfd() function returns the integer file descriptor associated with
     the named directory stream dirp (see open(2)).

EXAMPLES

     Sample code which searches a directory for entry "name" is:

           len = strlen(name);
           dirp = opendir(".");
           if (dirp) {
                   while ((dp = readdir(dirp)) != NULL)
                           if (dp->d_namlen == len && !strcmp(dp->d_name, name)) {
                                   (void)closedir(dirp);
                                   return (FOUND);
                           }
                   (void)closedir(dirp);
           }
           return (NOT_FOUND);

SEE ALSO

     close(2), getdirentries(2), lseek(2), open(2), dir(5)

HISTORY

     The opendir(), readdir(), telldir(), seekdir(), rewinddir(), closedir(),
     and dirfd() functions appeared in 4.2BSD.

MirOS BSD #10-current            June 4, 1993                                1

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