Move common dirent implementation from sysdeps/unix to sysdeps/posix.

1 files changed, 228 insertions, 0 deletions

diff --git a/sysdeps/posix/opendir.c b/sysdeps/posix/opendir.c
new file mode 100644
index 0000000000..e093142f62
--- /dev/null
+++ b/sysdeps/posix/opendir.c
@@ -0,0 +1,228 @@
+/* Copyright (C) 1991-1996,98,2000-2003,2005,2007,2009,2011
+   Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <assert.h>
+#include <errno.h>
+#include <limits.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <dirent.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <dirstream.h>
+#include <not-cancel.h>
+#include <kernel-features.h>
+
+
+/* opendir() must not accidentally open something other than a directory.
+   Some OS's have kernel support for that, some don't.  In the worst
+   case we have to stat() before the open() AND fstat() after.
+
+   We have to test at runtime for kernel support since libc may have
+   been compiled with different headers to the kernel it's running on.
+   This test can't be done reliably in the general case.  We'll use
+   /dev/null, which if it's not a device lots of stuff will break, as
+   a guinea pig.  It may be missing in chroot environments, so we
+   make sure to fail safe. */
+#ifdef O_DIRECTORY
+# ifdef O_DIRECTORY_WORKS
+#  define o_directory_works 1
+#  define tryopen_o_directory() while (1) /* This must not be called.  */
+# else
+static int o_directory_works;
+
+static void
+tryopen_o_directory (void)
+{
+  int serrno = errno;
+  int x = open_not_cancel_2 ("/dev/null", O_RDONLY|O_NDELAY|O_DIRECTORY);
+
+  if (x >= 0)
+    {
+      close_not_cancel_no_status (x);
+      o_directory_works = -1;
+    }
+  else if (errno != ENOTDIR)
+    o_directory_works = -1;
+  else
+    o_directory_works = 1;
+
+  __set_errno (serrno);
+}
+# endif
+# define EXTRA_FLAGS O_DIRECTORY
+#else
+# define EXTRA_FLAGS 0
+#endif
+
+
+DIR *
+internal_function
+__opendirat (int dfd, const char *name)
+{
+  struct stat64 statbuf;
+  struct stat64 *statp = NULL;
+
+  if (__builtin_expect (name[0], '\1') == '\0')
+    {
+      /* POSIX.1-1990 says an empty name gets ENOENT;
+	 but `open' might like it fine.  */
+      __set_errno (ENOENT);
+      return NULL;
+    }
+
+#ifdef O_DIRECTORY
+  /* Test whether O_DIRECTORY works.  */
+  if (o_directory_works == 0)
+    tryopen_o_directory ();
+
+  /* We can skip the expensive `stat' call if O_DIRECTORY works.  */
+  if (o_directory_works < 0)
+#endif
+    {
+      /* We first have to check whether the name is for a directory.  We
+	 cannot do this after the open() call since the open/close operation
+	 performed on, say, a tape device might have undesirable effects.  */
+      if (__builtin_expect (__xstat64 (_STAT_VER, name, &statbuf), 0) < 0)
+	return NULL;
+      if (__builtin_expect (! S_ISDIR (statbuf.st_mode), 0))
+	{
+	  __set_errno (ENOTDIR);
+	  return NULL;
+	 }
+    }
+
+  int flags = O_RDONLY|O_NDELAY|EXTRA_FLAGS|O_LARGEFILE;
+#ifdef O_CLOEXEC
+  flags |= O_CLOEXEC;
+#endif
+  int fd;
+#ifdef IS_IN_rtld
+  assert (dfd == AT_FDCWD);
+  fd = open_not_cancel_2 (name, flags);
+#else
+  fd = openat_not_cancel_3 (dfd, name, flags);
+#endif
+  if (__builtin_expect (fd, 0) < 0)
+    return NULL;
+
+#ifdef O_DIRECTORY
+  if (o_directory_works <= 0)
+#endif
+    {
+      /* Now make sure this really is a directory and nothing changed since
+	 the `stat' call.  */
+      if (__builtin_expect (__fxstat64 (_STAT_VER, fd, &statbuf), 0) < 0)
+	goto lose;
+      if (__builtin_expect (! S_ISDIR (statbuf.st_mode), 0))
+	{
+	  __set_errno (ENOTDIR);
+	lose:
+	  close_not_cancel_no_status (fd);
+	  return NULL;
+	}
+      statp = &statbuf;
+    }
+
+  return __alloc_dir (fd, true, 0, statp);
+}
+
+
+/* Open a directory stream on NAME.  */
+DIR *
+__opendir (const char *name)
+{
+  return __opendirat (AT_FDCWD, name);
+}
+weak_alias (__opendir, opendir)
+
+
+#ifdef __ASSUME_O_CLOEXEC
+# define check_have_o_cloexec(fd) 1
+#else
+static int
+check_have_o_cloexec (int fd)
+{
+  if (__have_o_cloexec == 0)
+    __have_o_cloexec = (__fcntl (fd, F_GETFD, 0) & FD_CLOEXEC) == 0 ? -1 : 1;
+  return __have_o_cloexec > 0;
+}
+#endif
+
+
+DIR *
+internal_function
+__alloc_dir (int fd, bool close_fd, int flags, const struct stat64 *statp)
+{
+  /* We always have to set the close-on-exit flag if the user provided
+     the file descriptor.  Otherwise only if we have no working
+     O_CLOEXEC support.  */
+#ifdef O_CLOEXEC
+  if ((! close_fd && (flags & O_CLOEXEC) == 0)
+      || ! check_have_o_cloexec (fd))
+#endif
+    {
+      if (__builtin_expect (__fcntl (fd, F_SETFD, FD_CLOEXEC), 0) < 0)
+	goto lose;
+    }
+
+  const size_t default_allocation = (4 * BUFSIZ < sizeof (struct dirent64)
+				     ? sizeof (struct dirent64) : 4 * BUFSIZ);
+  const size_t small_allocation = (BUFSIZ < sizeof (struct dirent64)
+				   ? sizeof (struct dirent64) : BUFSIZ);
+  size_t allocation = default_allocation;
+#ifdef _STATBUF_ST_BLKSIZE
+  if (statp != NULL && default_allocation < statp->st_blksize)
+    allocation = statp->st_blksize;
+#endif
+
+  DIR *dirp = (DIR *) malloc (sizeof (DIR) + allocation);
+  if (dirp == NULL)
+    {
+      allocation = small_allocation;
+      dirp = (DIR *) malloc (sizeof (DIR) + allocation);
+
+      if (dirp == NULL)
+      lose:
+	{
+	  if (close_fd)
+	    {
+	      int save_errno = errno;
+	      close_not_cancel_no_status (fd);
+	      __set_errno (save_errno);
+	    }
+	  return NULL;
+	}
+    }
+
+  dirp->fd = fd;
+#ifndef NOT_IN_libc
+  __libc_lock_init (dirp->lock);
+#endif
+  dirp->allocation = allocation;
+  dirp->size = 0;
+  dirp->offset = 0;
+  dirp->filepos = 0;
+
+  return dirp;
+}