1 files changed, 286 insertions, 0 deletions
diff --git a/lib/openat.c b/lib/openat.c
new file mode 100644
index 0000000..acbf7e3
--- /dev/null
+++ b/lib/openat.c
@@ -0,0 +1,286 @@
+/* provide a replacement openat function
+   Copyright (C) 2004-2016 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 3 of the License, 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, see <http://www.gnu.org/licenses/>.  */
+
+/* written by Jim Meyering */
+
+/* If the user's config.h happens to include <fcntl.h>, let it include only
+   the system's <fcntl.h> here, so that orig_openat doesn't recurse to
+   rpl_openat.  */
+#define __need_system_fcntl_h
+#include <config.h>
+
+/* Get the original definition of open.  It might be defined as a macro.  */
+#include <fcntl.h>
+#include <sys/types.h>
+#undef __need_system_fcntl_h
+
+#if HAVE_OPENAT
+static int
+orig_openat (int fd, char const *filename, int flags, mode_t mode)
+{
+  return openat (fd, filename, flags, mode);
+}
+#endif
+
+/* Write "fcntl.h" here, not <fcntl.h>, otherwise OSF/1 5.1 DTK cc eliminates
+   this include because of the preliminary #include <fcntl.h> above.  */
+#include "fcntl.h"
+
+#include "openat.h"
+
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <errno.h>
+
+#if HAVE_OPENAT
+
+/* Like openat, but work around Solaris 9 bugs with trailing slash.  */
+int
+rpl_openat (int dfd, char const *filename, int flags, ...)
+{
+  mode_t mode;
+  int fd;
+
+  mode = 0;
+  if (flags & O_CREAT)
+    {
+      va_list arg;
+      va_start (arg, flags);
+
+      /* We have to use PROMOTED_MODE_T instead of mode_t, otherwise GCC 4
+         creates crashing code when 'mode_t' is smaller than 'int'.  */
+      mode = va_arg (arg, PROMOTED_MODE_T);
+
+      va_end (arg);
+    }
+
+# if OPEN_TRAILING_SLASH_BUG
+  /* If the filename ends in a slash and one of O_CREAT, O_WRONLY, O_RDWR
+     is specified, then fail.
+     Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html>
+     says that
+       "A pathname that contains at least one non-slash character and that
+        ends with one or more trailing slashes shall be resolved as if a
+        single dot character ( '.' ) were appended to the pathname."
+     and
+       "The special filename dot shall refer to the directory specified by
+        its predecessor."
+     If the named file already exists as a directory, then
+       - if O_CREAT is specified, open() must fail because of the semantics
+         of O_CREAT,
+       - if O_WRONLY or O_RDWR is specified, open() must fail because POSIX
+         <http://www.opengroup.org/susv3/functions/open.html> says that it
+         fails with errno = EISDIR in this case.
+     If the named file does not exist or does not name a directory, then
+       - if O_CREAT is specified, open() must fail since open() cannot create
+         directories,
+       - if O_WRONLY or O_RDWR is specified, open() must fail because the
+         file does not contain a '.' directory.  */
+  if (flags & (O_CREAT | O_WRONLY | O_RDWR))
+    {
+      size_t len = strlen (filename);
+      if (len > 0 && filename[len - 1] == '/')
+        {
+          errno = EISDIR;
+          return -1;
+        }
+    }
+# endif
+
+  fd = orig_openat (dfd, filename, flags, mode);
+
+# if OPEN_TRAILING_SLASH_BUG
+  /* If the filename ends in a slash and fd does not refer to a directory,
+     then fail.
+     Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html>
+     says that
+       "A pathname that contains at least one non-slash character and that
+        ends with one or more trailing slashes shall be resolved as if a
+        single dot character ( '.' ) were appended to the pathname."
+     and
+       "The special filename dot shall refer to the directory specified by
+        its predecessor."
+     If the named file without the slash is not a directory, open() must fail
+     with ENOTDIR.  */
+  if (fd >= 0)
+    {
+      /* We know len is positive, since open did not fail with ENOENT.  */
+      size_t len = strlen (filename);
+      if (filename[len - 1] == '/')
+        {
+          struct stat statbuf;
+
+          if (fstat (fd, &statbuf) >= 0 && !S_ISDIR (statbuf.st_mode))
+            {
+              close (fd);
+              errno = ENOTDIR;
+              return -1;
+            }
+        }
+    }
+# endif
+
+  return fd;
+}
+
+#else /* !HAVE_OPENAT */
+
+# include "dosname.h" /* solely for definition of IS_ABSOLUTE_FILE_NAME */
+# include "openat-priv.h"
+# include "save-cwd.h"
+
+/* Replacement for Solaris' openat function.
+   <http://www.google.com/search?q=openat+site:docs.sun.com>
+   First, try to simulate it via open ("/proc/self/fd/FD/FILE").
+   Failing that, simulate it by doing save_cwd/fchdir/open/restore_cwd.
+   If either the save_cwd or the restore_cwd fails (relatively unlikely),
+   then give a diagnostic and exit nonzero.
+   Otherwise, upon failure, set errno and return -1, as openat does.
+   Upon successful completion, return a file descriptor.  */
+int
+openat (int fd, char const *file, int flags, ...)
+{
+  mode_t mode = 0;
+
+  if (flags & O_CREAT)
+    {
+      va_list arg;
+      va_start (arg, flags);
+
+      /* We have to use PROMOTED_MODE_T instead of mode_t, otherwise GCC 4
+         creates crashing code when 'mode_t' is smaller than 'int'.  */
+      mode = va_arg (arg, PROMOTED_MODE_T);
+
+      va_end (arg);
+    }
+
+  return openat_permissive (fd, file, flags, mode, NULL);
+}
+
+/* Like openat (FD, FILE, FLAGS, MODE), but if CWD_ERRNO is
+   nonnull, set *CWD_ERRNO to an errno value if unable to save
+   or restore the initial working directory.  This is needed only
+   the first time remove.c's remove_dir opens a command-line
+   directory argument.
+
+   If a previous attempt to restore the current working directory
+   failed, then we must not even try to access a '.'-relative name.
+   It is the caller's responsibility not to call this function
+   in that case.  */
+
+int
+openat_permissive (int fd, char const *file, int flags, mode_t mode,
+                   int *cwd_errno)
+{
+  struct saved_cwd saved_cwd;
+  int saved_errno;
+  int err;
+  bool save_ok;
+
+  if (fd == AT_FDCWD || IS_ABSOLUTE_FILE_NAME (file))
+    return open (file, flags, mode);
+
+  {
+    char buf[OPENAT_BUFFER_SIZE];
+    char *proc_file = openat_proc_name (buf, fd, file);
+    if (proc_file)
+      {
+        int open_result = open (proc_file, flags, mode);
+        int open_errno = errno;
+        if (proc_file != buf)
+          free (proc_file);
+        /* 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 <= open_result || ! EXPECTED_ERRNO (open_errno))
+          {
+            errno = open_errno;
+            return open_result;
+          }
+      }
+  }
+
+  save_ok = (save_cwd (&saved_cwd) == 0);
+  if (! save_ok)
+    {
+      if (! cwd_errno)
+        openat_save_fail (errno);
+      *cwd_errno = errno;
+    }
+  if (0 <= fd && fd == saved_cwd.desc)
+    {
+      /* If saving the working directory collides with the user's
+         requested fd, then the user's fd must have been closed to
+         begin with.  */
+      free_cwd (&saved_cwd);
+      errno = EBADF;
+      return -1;
+    }
+
+  err = fchdir (fd);
+  saved_errno = errno;
+
+  if (! err)
+    {
+      err = open (file, flags, mode);
+      saved_errno = errno;
+      if (save_ok && restore_cwd (&saved_cwd) != 0)
+        {
+          if (! cwd_errno)
+            {
+              /* Don't write a message to just-created fd 2.  */
+              saved_errno = errno;
+              if (err == STDERR_FILENO)
+                close (err);
+              openat_restore_fail (saved_errno);
+            }
+          *cwd_errno = errno;
+        }
+    }
+
+  free_cwd (&saved_cwd);
+  errno = saved_errno;
+  return err;
+}
+
+/* Return true if our openat implementation must resort to
+   using save_cwd and restore_cwd.  */
+bool
+openat_needs_fchdir (void)
+{
+  bool needs_fchdir = true;
+  int fd = open ("/", O_SEARCH);
+
+  if (0 <= fd)
+    {
+      char buf[OPENAT_BUFFER_SIZE];
+      char *proc_file = openat_proc_name (buf, fd, ".");
+      if (proc_file)
+        {
+          needs_fchdir = false;
+          if (proc_file != buf)
+            free (proc_file);
+        }
+      close (fd);
+    }
+
+  return needs_fchdir;
+}
+
+#endif /* !HAVE_OPENAT */