(mkdirat): New file and function.

1 files changed, 118 insertions, 0 deletions

diff --git a/lib/mkdirat.c b/lib/mkdirat.c
new file mode 100644
index 000000000..140f96a96
--- /dev/null
+++ b/lib/mkdirat.c
@@ -0,0 +1,118 @@
+/* provide a replacement openat function
+   Copyright (C) 2004, 2005 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+/* written by Jim Meyering */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "openat.h"
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+
+#include "alloca.h"
+#include "dirname.h" /* solely for definition of IS_ABSOLUTE_FILE_NAME */
+#include "intprops.h"
+#include "save-cwd.h"
+
+#include "gettext.h"
+#define _(msgid) gettext (msgid)
+
+/* Set PROC_FD_FILENAME to the expansion of "/proc/self/fd/%d/%s" in
+   alloca'd memory, using FD and FILE, respectively for %d and %s. */
+#define BUILD_PROC_NAME(Proc_fd_filename, Fd, File)			\
+  do									\
+    {									\
+      size_t filelen = strlen (File);					\
+      static const char procfd[] = "/proc/self/fd/%d/%s";		\
+      /* Buffer for the file name we are going to use.  It consists of	\
+	 - the string /proc/self/fd/					\
+	 - the file descriptor number					\
+	 - the file name provided.					\
+	 The final NUL is included in the sizeof.			\
+	 Subtract 4 to account for %d and %s.  */			\
+      size_t buflen = sizeof (procfd) - 4 + INT_STRLEN_BOUND (Fd) + filelen; \
+      (Proc_fd_filename) = alloca (buflen);				\
+      snprintf ((Proc_fd_filename), buflen, procfd, (Fd), (File));	\
+    }									\
+  while (0)
+
+/* Trying to access a BUILD_PROC_NAME file will fail on systems without
+   /proc support, and even on systems *with* ProcFS support.  Return
+   nonzero if the failure may be legitimate, e.g., because /proc is not
+   readable, or the particular .../fd/N directory is not present.  */
+#define EXPECTED_ERRNO(Errno) \
+  ((Errno) == ENOTDIR || (Errno) == ENOENT \
+   || (Errno) == EPERM || (Errno) == EACCES \
+   || (Errno) == EOPNOTSUPP /* FreeBSD */)
+
+/* Solaris 10 has no function like this.
+   Create a subdirectory, FILE, with mode MODE, in the directory
+   open on descriptor FD.  If possible, do it without changing the
+   working directory.  Otherwise, resort to using save_cwd/fchdir,
+   then mkdir/restore_cwd.  If either the save_cwd or the restore_cwd
+   fails, then give a diagnostic and exit nonzero.  */
+int
+mkdirat (int fd, char const *file, mode_t mode)
+{
+  struct saved_cwd saved_cwd;
+  int saved_errno;
+  int err;
+
+  if (fd == AT_FDCWD || IS_ABSOLUTE_FILE_NAME (file))
+    return mkdir (file, mode);
+
+  {
+    char *proc_file;
+    BUILD_PROC_NAME (proc_file, fd, file);
+    err = mkdir (proc_file, mode);
+    /* If the syscall succeeds, or if it fails with an unexpected
+       errno value, then return right away.  Otherwise, fall through
+       and resort to using save_cwd/restore_cwd.  */
+    if (0 <= err || ! EXPECTED_ERRNO (errno))
+      return err;
+  }
+
+  if (save_cwd (&saved_cwd) != 0)
+    openat_save_fail (errno);
+
+  if (fchdir (fd) != 0)
+    {
+      saved_errno = errno;
+      free_cwd (&saved_cwd);
+      errno = saved_errno;
+      return -1;
+    }
+
+  err = mkdir (file, mode);
+  saved_errno = (err < 0 ? errno : 0);
+
+  if (restore_cwd (&saved_cwd) != 0)
+    openat_restore_fail (errno);
+
+  free_cwd (&saved_cwd);
+
+  if (saved_errno)
+    errno = saved_errno;
+  return err;
+}