1 files changed, 157 insertions, 0 deletions

diff --git a/gl/ftello.c b/gl/ftello.c
new file mode 100644
index 00000000..f701aa63
--- /dev/null
+++ b/gl/ftello.c
@@ -0,0 +1,157 @@
+/* An ftello() function that works around platform bugs.
+   Copyright (C) 2007, 2009-2021 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/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <stdio.h>
+
+#include <errno.h>
+#include "intprops.h"
+
+/* Get lseek.  */
+#include <unistd.h>
+
+#include "stdio-impl.h"
+
+off_t
+ftello (FILE *fp)
+#undef ftello
+#if !HAVE_FTELLO
+# undef ftell
+# define ftello ftell
+#endif
+#if _GL_WINDOWS_64_BIT_OFF_T
+# undef ftello
+# if HAVE__FTELLI64 /* msvc, mingw64 */
+#  define ftello _ftelli64
+# else /* mingw */
+#  define ftello ftello64
+# endif
+#endif
+{
+#if FTELLO_BROKEN_AFTER_UNGETC /* macOS >= 10.15 */
+  /* The system's ftello() is completely broken, because it calls __sflush,
+     which makes side effects on the stream.  */
+
+  /* Handle non-seekable files first.  */
+  if (fp->_file < 0 || fp->_seek == NULL)
+    {
+      errno = ESPIPE;
+      return -1;
+    }
+
+  /* Determine the current offset, ignoring buffered and pushed-back bytes.  */
+  off_t pos;
+
+  if (fp->_flags & __SOFF)
+    pos = fp->_offset;
+  else
+    {
+      pos = fp->_seek (fp->_cookie, 0, SEEK_CUR);
+      if (pos < 0)
+        return -1;
+      if (fp->_flags & __SOPT)
+        {
+          fp->_offset = pos;
+          fp->_flags |= __SOFF;
+        }
+    }
+
+  if (fp->_flags & __SRD)
+    {
+      /* Now consider buffered and pushed-back bytes from ungetc.  */
+      if (fp->_ub._base != NULL)
+        /* Considering the buffered bytes, we are at position
+             pos - fp->_ur.
+           Considering also the pushed-back bytes, we are at position
+             pos - fp->_ur - fp->_r.  */
+        pos = pos - fp->_ur - fp->_r;
+      else
+        /* Considering the buffered bytes, we are at position
+             pos - fp->_r.  */
+        pos = pos - fp->_r;
+      if (pos < 0)
+        {
+          errno = EIO;
+          return -1;
+        }
+    }
+  else if ((fp->_flags & __SWR) && fp->_p != NULL)
+    {
+      /* Consider the buffered bytes.  */
+      off_t buffered = fp->_p - fp->_bf._base;
+
+      /* Compute pos + buffered, with overflow check.  */
+      off_t sum;
+      if (! INT_ADD_OK (pos, buffered, &sum))
+        {
+          errno = EOVERFLOW;
+          return -1;
+        }
+      pos = sum;
+    }
+
+  return pos;
+
+#else
+
+# if LSEEK_PIPE_BROKEN
+  /* mingw gives bogus answers rather than failure on non-seekable files.  */
+  if (lseek (fileno (fp), 0, SEEK_CUR) == -1)
+    return -1;
+# endif
+
+# if FTELLO_BROKEN_AFTER_SWITCHING_FROM_READ_TO_WRITE /* Solaris */
+  /* The Solaris stdio leaves the _IOREAD flag set after reading from a file
+     reaches EOF and the program then starts writing to the file.  ftello
+     gets confused by this.  */
+  if (fp_->_flag & _IOWRT)
+    {
+      off_t pos;
+
+      /* Call ftello nevertheless, for the side effects that it does on fp.  */
+      ftello (fp);
+
+      /* Compute the file position ourselves.  */
+      pos = lseek (fileno (fp), (off_t) 0, SEEK_CUR);
+      if (pos >= 0)
+        {
+          if ((fp_->_flag & _IONBF) == 0 && fp_->_base != NULL)
+            pos += fp_->_ptr - fp_->_base;
+        }
+      return pos;
+    }
+# endif
+
+# if defined __SL64 && defined __SCLE /* Cygwin */
+  if ((fp->_flags & __SL64) == 0)
+    {
+      /* Cygwin 1.5.0 through 1.5.24 failed to open stdin in 64-bit
+         mode; but has an ftello that requires 64-bit mode.  */
+      FILE *tmp = fopen ("/dev/null", "r");
+      if (!tmp)
+        return -1;
+      fp->_flags |= __SL64;
+      fp->_seek64 = tmp->_seek64;
+      fclose (tmp);
+    }
+# endif
+
+  return ftello (fp);
+
+#endif
+}