File gnulib-74d9d6a293d7462dea8f83e7fc5ac792e956a0ad-excerpt.patch of Package gcal

commit 74d9d6a293d7462dea8f83e7fc5ac792e956a0ad
Author: Paul Eggert <eggert@cs.ucla.edu>
Date:   Thu Mar 8 16:42:45 2018 -0800

    fflush: be more paranoid about libio.h change
    
    Suggested by Eli Zaretskii in:
    https://lists.gnu.org/r/emacs-devel/2018-03/msg00270.html
    * lib/fbufmode.c (fbufmode):
    * lib/fflush.c (clear_ungetc_buffer_preserving_position)
    (disable_seek_optimization, rpl_fflush):
    * lib/fpending.c (__fpending):
    * lib/fpurge.c (fpurge):
    * lib/freadable.c (freadable):
    * lib/freadahead.c (freadahead):
    * lib/freading.c (freading):
    * lib/freadptr.c (freadptr):
    * lib/freadseek.c (freadptrinc):
    * lib/fseeko.c (fseeko):
    * lib/fseterr.c (fseterr):
    * lib/fwritable.c (fwritable):
    * lib/fwriting.c (fwriting):
    Look at _IO_ftrylockfile as well as at _IO_EOF_SEEN.

diff --git a/lib/fflush.c b/lib/fflush.c
index a6edfa105..a140b7ad9 100644
--- a/lib/fflush.c
+++ b/lib/fflush.c
@@ -33,7 +33,8 @@
 #undef fflush
 
 
-#if defined _IO_EOF_SEEN || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */
+#if defined _IO_EOF_SEEN || defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1
+/* GNU libc, BeOS, Haiku, Linux libc5 */
 
 /* Clear the stream's ungetc buffer, preserving the value of ftello (fp).  */
 static void
@@ -72,7 +73,8 @@ clear_ungetc_buffer (FILE *fp)
 
 #endif
 
-#if ! (defined _IO_EOF_SEEN || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */)
+#if ! (defined _IO_EOF_SEEN || defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1)
+/* GNU libc, BeOS, Haiku, Linux libc5 */
 
 # if (defined __sferror || defined __DragonFly__ || defined __ANDROID__) && defined __SNPT
 /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */
@@ -148,7 +150,8 @@ rpl_fflush (FILE *stream)
   if (stream == NULL || ! freading (stream))
     return fflush (stream);
 
-#if defined _IO_EOF_SEEN || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */
+#if defined _IO_EOF_SEEN || defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1
+  /* GNU libc, BeOS, Haiku, Linux libc5 */
 
   clear_ungetc_buffer_preserving_position (stream);
 
diff --git a/lib/fpurge.c b/lib/fpurge.c
index 3aedcc373..554790b56 100644
--- a/lib/fpurge.c
+++ b/lib/fpurge.c
@@ -62,7 +62,8 @@ fpurge (FILE *fp)
   /* Most systems provide FILE as a struct and the necessary bitmask in
      <stdio.h>, because they need it for implementing getc() and putc() as
      fast macros.  */
-# if defined _IO_EOF_SEEN || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */
+# if defined _IO_EOF_SEEN || defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1
+  /* GNU libc, BeOS, Haiku, Linux libc5 */
   fp->_IO_read_end = fp->_IO_read_ptr;
   fp->_IO_write_ptr = fp->_IO_write_base;
   /* Avoid memory leak when there is an active ungetc buffer.  */
diff --git a/lib/freading.c b/lib/freading.c
index c24d0c88a..790f92ca3 100644
--- a/lib/freading.c
+++ b/lib/freading.c
@@ -31,7 +31,8 @@ freading (FILE *fp)
   /* Most systems provide FILE as a struct and the necessary bitmask in
      <stdio.h>, because they need it for implementing getc() and putc() as
      fast macros.  */
-# if defined _IO_EOF_SEEN || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */
+# if defined _IO_EOF_SEEN || defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1
+  /* GNU libc, BeOS, Haiku, Linux libc5 */
   return ((fp->_flags & _IO_NO_WRITES) != 0
           || ((fp->_flags & (_IO_NO_READS | _IO_CURRENTLY_PUTTING)) == 0
               && fp->_IO_read_base != NULL));
diff --git a/lib/fseeko.c b/lib/fseeko.c
index 193f4e8ce..e5c5172e7 100644
--- a/lib/fseeko.c
+++ b/lib/fseeko.c
@@ -47,7 +47,8 @@ fseeko (FILE *fp, off_t offset, int whence)
 #endif
 
   /* These tests are based on fpurge.c.  */
-#if defined _IO_EOF_SEEN || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */
+#if defined _IO_EOF_SEEN || defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1
+  /* GNU libc, BeOS, Haiku, Linux libc5 */
   if (fp->_IO_read_end == fp->_IO_read_ptr
       && fp->_IO_write_ptr == fp->_IO_write_base
       && fp->_IO_save_base == NULL)
@@ -123,7 +124,8 @@ fseeko (FILE *fp, off_t offset, int whence)
           return -1;
         }
 
-#if defined _IO_EOF_SEEN || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */
+#if defined _IO_EOF_SEEN || defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1
+      /* GNU libc, BeOS, Haiku, Linux libc5 */
       fp->_flags &= ~_IO_EOF_SEEN;
       fp->_offset = pos;
 #elif defined __sferror || defined __DragonFly__ || defined __ANDROID__