1 files changed, 95 insertions, 0 deletions
diff --git a/lib/openat-proc.c b/lib/openat-proc.c
new file mode 100644
index 0000000..ff2fff0
--- /dev/null
+++ b/lib/openat-proc.c
@@ -0,0 +1,95 @@
+/* Create /proc/self/fd-related names for subfiles of open directories.
+
+   Copyright (C) 2006 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 Paul Eggert.  */
+
+#include <config.h>
+
+#include "openat-priv.h"
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include <stdio.h>
+#include <string.h>
+
+#include "dirname.h"
+#include "intprops.h"
+#include "same-inode.h"
+#include "xalloc.h"
+
+/* The results of open() in this file are not used with fchdir,
+   therefore save some unnecessary work in fchdir.c.  */
+#undef open
+#undef close
+
+#define PROC_SELF_FD_FORMAT "/proc/self/fd/%d/%s"
+
+#define PROC_SELF_FD_NAME_SIZE_BOUND(len) \
+  (sizeof PROC_SELF_FD_FORMAT - sizeof "%d%s" \
+   + INT_STRLEN_BOUND (int) + (len) + 1)
+
+
+/* Set BUF to the expansion of PROC_SELF_FD_FORMAT, using FD and FILE
+   respectively for %d and %s.  If successful, return BUF if the
+   result fits in BUF, dynamically allocated memory otherwise.  But
+   return NULL if /proc is not reliable.  */
+char *
+openat_proc_name (char buf[OPENAT_BUFFER_SIZE], int fd, char const *file)
+{
+  static int proc_status = 0;
+
+  if (! proc_status)
+    {
+      /* Set PROC_STATUS to a positive value if /proc/self/fd is
+	 reliable, and a negative value otherwise.  Solaris 10
+	 /proc/self/fd mishandles "..", and any file name might expand
+	 to ".." after symbolic link expansion, so avoid /proc/self/fd
+	 if it mishandles "..".  Solaris 10 has openat, but this
+	 problem is exhibited on code that built on Solaris 8 and
+	 running on Solaris 10.  */
+
+      int proc_self_fd = open ("/proc/self/fd", O_RDONLY);
+      if (proc_self_fd < 0)
+	proc_status = -1;
+      else
+	{
+	  struct stat proc_self_fd_dotdot_st;
+	  struct stat proc_self_st;
+	  char dotdot_buf[PROC_SELF_FD_NAME_SIZE_BOUND (sizeof ".." - 1)];
+	  sprintf (dotdot_buf, PROC_SELF_FD_FORMAT, proc_self_fd, "..");
+	  proc_status =
+	    ((stat (dotdot_buf, &proc_self_fd_dotdot_st) == 0
+	      && stat ("/proc/self", &proc_self_st) == 0
+	      && SAME_INODE (proc_self_fd_dotdot_st, proc_self_st))
+	     ? 1 : -1);
+	  close (proc_self_fd);
+	}
+    }
+
+  if (proc_status < 0)
+    return NULL;
+  else
+    {
+      size_t bufsize = PROC_SELF_FD_NAME_SIZE_BOUND (strlen (file));
+      char *result = (bufsize < OPENAT_BUFFER_SIZE ? buf : xmalloc (bufsize));
+      sprintf (result, PROC_SELF_FD_FORMAT, fd, file);
+      return result;
+    }
+}