1 files changed, 107 insertions, 0 deletions
diff --git a/lib/fopen.c b/lib/fopen.c
new file mode 100644
index 0000000..a3128fa
--- /dev/null
+++ b/lib/fopen.c
@@ -0,0 +1,107 @@
+/* Open a stream to a file.
+   Copyright (C) 2007-2020 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 <https://www.gnu.org/licenses/>.  */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2007.  */
+
+/* If the user's config.h happens to include <stdio.h>, let it include only
+   the system's <stdio.h> here, so that orig_fopen doesn't recurse to
+   rpl_fopen.  */
+#define __need_FILE
+#include <config.h>
+
+/* Get the original definition of fopen.  It might be defined as a macro.  */
+#include <stdio.h>
+#undef __need_FILE
+
+static FILE *
+orig_fopen (const char *filename, const char *mode)
+{
+  return fopen (filename, mode);
+}
+
+/* Specification.  */
+/* Write "stdio.h" here, not <stdio.h>, otherwise OSF/1 5.1 DTK cc eliminates
+   this include because of the preliminary #include <stdio.h> above.  */
+#include "stdio.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+FILE *
+rpl_fopen (const char *filename, const char *mode)
+{
+#if defined _WIN32 && ! defined __CYGWIN__
+  if (strcmp (filename, "/dev/null") == 0)
+    filename = "NUL";
+#endif
+
+#if FOPEN_TRAILING_SLASH_BUG
+  /* Fail if the mode requires write access and the filename ends in a slash,
+     as POSIX says such a filename must name a directory
+     <https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_13>:
+       "A pathname that contains at least one non-<slash> character and that
+        ends with one or more trailing <slash> characters shall not be resolved
+        successfully unless the last pathname component before the trailing
+        <slash> characters names an existing directory"
+     If the named file already exists as a directory, then if a mode that
+     requires write access is specified, fopen() must fail because POSIX
+     <https://pubs.opengroup.org/onlinepubs/9699919799/functions/fopen.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
+     fopen() must fail since the file does not contain a '.' directory.  */
+  {
+    size_t len = strlen (filename);
+    if (len > 0 && filename[len - 1] == '/')
+      {
+        int fd;
+        struct stat statbuf;
+        FILE *fp;
+
+        if (mode[0] == 'w' || mode[0] == 'a')
+          {
+            errno = EISDIR;
+            return NULL;
+          }
+
+        fd = open (filename, O_RDONLY);
+        if (fd < 0)
+          return NULL;
+
+        if (fstat (fd, &statbuf) >= 0 && !S_ISDIR (statbuf.st_mode))
+          {
+            close (fd);
+            errno = ENOTDIR;
+            return NULL;
+          }
+
+        fp = fdopen (fd, mode);
+        if (fp == NULL)
+          {
+            int saved_errno = errno;
+            close (fd);
+            errno = saved_errno;
+          }
+        return fp;
+      }
+  }
+# endif
+
+  return orig_fopen (filename, mode);
+}