5 files changed, 121 insertions, 9 deletions
diff --git a/libio/Makefile b/libio/Makefile
index 3e08ed0eeb..cbe14a8e25 100644
--- a/libio/Makefile
+++ b/libio/Makefile
@@ -64,7 +64,8 @@ tests = tst_swprintf tst_wprintf tst_swscanf tst_wscanf tst_getwc tst_putwc   \
 	bug-memstream1 bug-wmemstream1 \
 	tst-setvbuf1 tst-popen1 tst-fgetwc bug-wsetpos tst-fseek \
 	tst-fwrite-error tst-ftell-partial-wide tst-ftell-active-handler \
-	tst-ftell-append tst-fputws tst-bz22415
+	tst-ftell-append tst-fputws tst-bz22415 tst-fgetc-after-eof
+
 ifeq (yes,$(build-shared))
 # Add test-fopenloc only if shared library is enabled since it depends on
 # shared localedata objects.
diff --git a/libio/fileops.c b/libio/fileops.c
index 79ad15351f..c9c5cbcc3c 100644
--- a/libio/fileops.c
+++ b/libio/fileops.c
@@ -468,11 +468,10 @@ int
 _IO_new_file_underflow (FILE *fp)
 {
   ssize_t count;
-#if 0
-  /* SysV does not make this test; take it out for compatibility */
+
+  /* C99 requires EOF to be "sticky".  */
   if (fp->_flags & _IO_EOF_SEEN)
-    return (EOF);
-#endif
+    return EOF;
 
   if (fp->_flags & _IO_NO_READS)
     {
diff --git a/libio/oldfileops.c b/libio/oldfileops.c
index 7997ddf90b..5e60c8c168 100644
--- a/libio/oldfileops.c
+++ b/libio/oldfileops.c
@@ -294,11 +294,10 @@ attribute_compat_text_section
 _IO_old_file_underflow (FILE *fp)
 {
   ssize_t count;
-#if 0
-  /* SysV does not make this test; take it out for compatibility */
+
+  /* C99 requires EOF to be "sticky".  */
   if (fp->_flags & _IO_EOF_SEEN)
-    return (EOF);
-#endif
+    return EOF;
 
   if (fp->_flags & _IO_NO_READS)
     {
diff --git a/libio/tst-fgetc-after-eof.c b/libio/tst-fgetc-after-eof.c
new file mode 100644
index 0000000000..81c9cc9940
--- /dev/null
+++ b/libio/tst-fgetc-after-eof.c
@@ -0,0 +1,109 @@
+/* Bug 1190: EOF conditions are supposed to be sticky.
+   Copyright (C) 2018 Free Software Foundation.
+   Copying and distribution of this file, with or without modification,
+   are permitted in any medium without royalty provided the copyright
+   notice and this notice are preserved. This file is offered as-is,
+   without any warranty.  */
+
+/* ISO C1999 specification of fgetc:
+
+       #include <stdio.h>
+       int fgetc (FILE *stream);
+
+   Description
+
+     If the end-of-file indicator for the input stream pointed to by
+     stream is not set and a next character is present, the fgetc
+     function obtains that character as an unsigned char converted to
+     an int and advances the associated file position indicator for
+     the stream (if defined).
+
+   Returns
+
+     If the end-of-file indicator for the stream is set, or if the
+     stream is at end-of-file, the end-of-file indicator for the
+     stream is set and the fgetc function returns EOF. Otherwise, the
+     fgetc function returns the next character from the input stream
+     pointed to by stream. If a read error occurs, the error indicator
+     for the stream is set and the fgetc function returns EOF.
+
+   The requirement to return EOF "if the end-of-file indicator for the
+   stream is set" was new in C99; the language in the 1989 edition of
+   the standard was ambiguous.  Historically, BSD-derived Unix always
+   had the C99 behavior, whereas in System V fgetc would attempt to
+   call read() again before returning EOF again.  Prior to version 2.28,
+   glibc followed the System V behavior even though this does not
+   comply with C99.
+
+   See
+   <https://sourceware.org/bugzilla/show_bug.cgi?id=1190>,
+   <https://sourceware.org/bugzilla/show_bug.cgi?id=19476>,
+   and the thread at
+   <https://sourceware.org/ml/libc-alpha/2012-09/msg00343.html>
+   for more detail.  */
+
+#include <support/tty.h>
+#include <support/check.h>
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#define XWRITE(fd, s, msg) do {                         \
+    if (write (fd, s, sizeof s - 1) != sizeof s - 1)    \
+      {                                                 \
+        perror ("write " msg);                          \
+        return 1;                                       \
+      }                                                 \
+  } while (0)
+
+int
+do_test (void)
+{
+  /* The easiest way to set up the conditions under which you can
+     notice whether the end-of-file indicator is sticky, is with a
+     pseudo-tty.  This is also the case which applications are most
+     likely to care about.  And it avoids any question of whether and
+     how it is legitimate to access the same physical file with two
+     independent FILE objects.  */
+  int outer_fd, inner_fd;
+  FILE *fp;
+
+  support_openpty (&outer_fd, &inner_fd, 0, 0, 0);
+  fp = fdopen (inner_fd, "r+");
+  if (!fp)
+    {
+      perror ("fdopen");
+      return 1;
+    }
+
+  XWRITE (outer_fd, "abc\n\004", "first line + EOF");
+  TEST_COMPARE (fgetc (fp), 'a');
+  TEST_COMPARE (fgetc (fp), 'b');
+  TEST_COMPARE (fgetc (fp), 'c');
+  TEST_COMPARE (fgetc (fp), '\n');
+  TEST_COMPARE (fgetc (fp), EOF);
+
+  TEST_VERIFY_EXIT (feof (fp));
+  TEST_VERIFY_EXIT (!ferror (fp));
+
+  XWRITE (outer_fd, "d\n", "second line");
+
+  /* At this point, there is a new full line of input waiting in the
+     kernelside input buffer, but we should still observe EOF from
+     stdio, because the end-of-file indicator has not been cleared.  */
+  TEST_COMPARE (fgetc (fp), EOF);
+
+  /* Clearing EOF should reveal the next line of input.  */
+  clearerr (fp);
+  TEST_COMPARE (fgetc (fp), 'd');
+  TEST_COMPARE (fgetc (fp), '\n');
+
+  fclose (fp);
+  close (outer_fd);
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/libio/wfileops.c b/libio/wfileops.c
index 1dbf72f797..63cb687652 100644
--- a/libio/wfileops.c
+++ b/libio/wfileops.c
@@ -116,6 +116,10 @@ _IO_wfile_underflow (FILE *fp)
   enum __codecvt_result status;
   ssize_t count;
 
+  /* C99 requires EOF to be "sticky".  */
+  if (fp->_flags & _IO_EOF_SEEN)
+    return WEOF;
+
   if (__glibc_unlikely (fp->_flags & _IO_NO_READS))
     {
       fp->_flags |= _IO_ERR_SEEN;