1 files changed, 229 insertions, 0 deletions

diff --git a/gl/fopen.c b/gl/fopen.c
new file mode 100644
index 00000000..f8469a0b
--- /dev/null
+++ b/gl/fopen.c
@@ -0,0 +1,229 @@
+/* Open a stream to a file.
+   Copyright (C) 2007-2023 Free Software Foundation, Inc.
+
+   This file 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.
+
+   This file 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 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 _GL_ALREADY_INCLUDING_STDIO_H
+#include <config.h>
+
+/* Get the original definition of fopen.  It might be defined as a macro.  */
+#include <stdio.h>
+#undef _GL_ALREADY_INCLUDING_STDIO_H
+
+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)
+{
+  int open_direction;
+  int open_flags;
+#if GNULIB_FOPEN_GNU
+  bool open_flags_gnu;
+# define BUF_SIZE 80
+  char fdopen_mode_buf[BUF_SIZE + 1];
+#endif
+
+#if defined _WIN32 && ! defined __CYGWIN__
+  if (strcmp (filename, "/dev/null") == 0)
+    filename = "NUL";
+#endif
+
+  /* Parse the mode.  */
+  open_direction = 0;
+  open_flags = 0;
+#if GNULIB_FOPEN_GNU
+  open_flags_gnu = false;
+#endif
+  {
+    const char *p = mode;
+#if GNULIB_FOPEN_GNU
+    char *q = fdopen_mode_buf;
+#endif
+
+    for (; *p != '\0'; p++)
+      {
+        switch (*p)
+          {
+          case 'r':
+            open_direction = O_RDONLY;
+#if GNULIB_FOPEN_GNU
+            if (q < fdopen_mode_buf + BUF_SIZE)
+              *q++ = *p;
+#endif
+            continue;
+          case 'w':
+            open_direction = O_WRONLY;
+            open_flags |= O_CREAT | O_TRUNC;
+#if GNULIB_FOPEN_GNU
+            if (q < fdopen_mode_buf + BUF_SIZE)
+              *q++ = *p;
+#endif
+            continue;
+          case 'a':
+            open_direction = O_WRONLY;
+            open_flags |= O_CREAT | O_APPEND;
+#if GNULIB_FOPEN_GNU
+            if (q < fdopen_mode_buf + BUF_SIZE)
+              *q++ = *p;
+#endif
+            continue;
+          case 'b':
+            /* While it is non-standard, O_BINARY is guaranteed by
+               gnulib <fcntl.h>.  We can also assume that orig_fopen
+               supports the 'b' flag.  */
+            open_flags |= O_BINARY;
+#if GNULIB_FOPEN_GNU
+            if (q < fdopen_mode_buf + BUF_SIZE)
+              *q++ = *p;
+#endif
+            continue;
+          case '+':
+            open_direction = O_RDWR;
+#if GNULIB_FOPEN_GNU
+            if (q < fdopen_mode_buf + BUF_SIZE)
+              *q++ = *p;
+#endif
+            continue;
+#if GNULIB_FOPEN_GNU
+          case 'x':
+            open_flags |= O_EXCL;
+            open_flags_gnu = true;
+            continue;
+          case 'e':
+            open_flags |= O_CLOEXEC;
+            open_flags_gnu = true;
+            continue;
+#endif
+          default:
+            break;
+          }
+#if GNULIB_FOPEN_GNU
+        /* The rest of the mode string can be a platform-dependent extension.
+           Copy it unmodified.  */
+        {
+          size_t len = strlen (p);
+          if (len > fdopen_mode_buf + BUF_SIZE - q)
+            len = fdopen_mode_buf + BUF_SIZE - q;
+          memcpy (q, p, len);
+          q += len;
+        }
+#endif
+        break;
+      }
+#if GNULIB_FOPEN_GNU
+    *q = '\0';
+#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 (open_direction != O_RDONLY)
+          {
+            errno = EISDIR;
+            return NULL;
+          }
+
+        fd = open (filename, open_direction | open_flags,
+                   S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
+        if (fd < 0)
+          return NULL;
+
+        if (fstat (fd, &statbuf) >= 0 && !S_ISDIR (statbuf.st_mode))
+          {
+            close (fd);
+            errno = ENOTDIR;
+            return NULL;
+          }
+
+# if GNULIB_FOPEN_GNU
+        fp = fdopen (fd, fdopen_mode_buf);
+# else
+        fp = fdopen (fd, mode);
+# endif
+        if (fp == NULL)
+          {
+            int saved_errno = errno;
+            close (fd);
+            errno = saved_errno;
+          }
+        return fp;
+      }
+  }
+#endif
+
+#if GNULIB_FOPEN_GNU
+  if (open_flags_gnu)
+    {
+      int fd;
+      FILE *fp;
+
+      fd = open (filename, open_direction | open_flags,
+                 S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
+      if (fd < 0)
+        return NULL;
+
+      fp = fdopen (fd, fdopen_mode_buf);
+      if (fp == NULL)
+        {
+          int saved_errno = errno;
+          close (fd);
+          errno = saved_errno;
+        }
+      return fp;
+    }
+#endif
+
+  return orig_fopen (filename, mode);
+}