add fdopendir(3) implementation (1/?)

POSIX states that the file offset of the passed descriptor determines the
directory entry read but this commit supports only descriptors with null
offsets.

Also add __fdopendir2() for symmetry with opendir/__opendir2().

diff --git a/include/dirent.h b/include/dirent.h
index 4d4b642..070baa5 100644 (file)
--- a/include/dirent.h
+++ b/include/dirent.h
@@ -84,11 +84,13 @@ typedef struct _dirdesc {
 
 __BEGIN_DECLS
 DIR *opendir (const char *);
+DIR *fdopendir (int);
 struct dirent *readdir (DIR *);
 void rewinddir (DIR *);
 int closedir (DIR *);
 #ifndef _POSIX_SOURCE
 DIR *__opendir2 (const char *, int);
+DIR *__fdopendir2 (int, int);
 long telldir (const DIR *);
 struct dirent *_readdir_unlocked(DIR *, int);
 void seekdir(DIR *, long);

diff --git a/lib/libc/gen/opendir.c b/lib/libc/gen/opendir.c
index f45eb2d..49eae64 100644 (file)
--- a/lib/libc/gen/opendir.c
+++ b/lib/libc/gen/opendir.c
@@ -48,27 +48,38 @@
 #include <unistd.h>
 #include "un-namespace.h"
 
+
+#define DEFAULT_FLAGS (DTF_HIDEW | DTF_NODUP)
+
 /*
- * Open a directory.
+ * Open a directory given its path.
  */
 DIR *
 opendir(const char *name)
 {
-       return (__opendir2(name, DTF_HIDEW|DTF_NODUP));
+       return (__opendir2(name, DEFAULT_FLAGS));
+}
+
+/*
+ * Open a directory given a descriptor representing it.
+ */
+DIR *
+fdopendir(int fd)
+{
+       return (__fdopendir2(fd, DEFAULT_FLAGS));
 }
 
 DIR *
 __opendir2(const char *name, int flags)
 {
-       DIR *dirp;
        int fd;
-       int incr;
-       int saved_errno;
        struct stat statb;
+       DIR *dirp;
+       int saved_errno;
 
        /*
         * stat() before _open() because opening of special files may be
-        * harmful.  _fstat() after open because the file may have changed.
+        * harmful.
         */
        if (stat(name, &statb) != 0)
                return (NULL);
@@ -76,9 +87,30 @@ __opendir2(const char *name, int flags)
                errno = ENOTDIR;
                return (NULL);
        }
+
        if ((fd = _open(name, O_RDONLY | O_NONBLOCK)) == -1)
                return (NULL);
+       dirp = __fdopendir2(fd, flags);
+       if (dirp == NULL) {
+               saved_errno = errno;
+               _close(fd);
+               errno = saved_errno;
+       }
+
+       return (dirp);
+}
+
+DIR *
+__fdopendir2(int fd, int flags)
+{
+       DIR *dirp;
+       int incr;
+       int saved_errno;
+       struct stat statb;
+       off_t off;
+
        dirp = NULL;
+
        if (_fstat(fd, &statb) != 0)
                goto fail;
        if (!S_ISDIR(statb.st_mode)) {
@@ -90,6 +122,16 @@ __opendir2(const char *name, int flags)
                goto fail;
 
        /*
+        * XXX We don't support yet the POSIX requirement that states that the
+        * file offset associated with the fd passed to fdopendir() determines
+        * which directory entry is returned.
+        */
+       if ((off = lseek(fd, 0, SEEK_CUR)) != 0) {
+               errno = (off != -1) ? ENOTSUP : errno;
+               goto fail;
+       }
+
+       /*
         * Use the system page size if that is a multiple of DIRBLKSIZ.
         * Hopefully this can be a big win someday by allowing page
         * trades to user space to be done by _getdirentries().
@@ -120,7 +162,6 @@ __opendir2(const char *name, int flags)
 fail:
        saved_errno = errno;
        free(dirp);
-       _close(fd);
        errno = saved_errno;
        return (NULL);
 }