* libio/fileops.c (_IO_file_sync_mmap): New function.

(_IO_file_jumps_mmap): Use it.
	(_IO_file_underflow_mmap): Rewritten.  If after EOF or fflush,
	repeat the stat check and resize the mapped buffer as necessary.

2002-07-31  Roland McGrath  <roland@frob.com>

	* libio/fileops.c (decide_maybe_mmap): New static function.
	Code taken from libio/iofopen.c:__fopen_maybe_mmap to try to
	mmap the file contents.  Then switch the jump tables to the mmap
	tables if it worked, or the vanilla file tables if not.
	(_IO_file_underflow_maybe_mmap): New function.
	(_IO_file_seekoff_maybe_mmap): New function.
	(_IO_file_xsgetn_maybe_mmap): New function.
	(_IO_file_jumps_maybe_mmap): New variable, jump table using those.
	* libio/libioP.h: Declare those.
	* libio/wfileops.c (_IO_wfile_underflow_maybe_mmap): New function.
	(_IO_wfile_jumps_maybe_mmap): New variable, jump table using that.
	* libio/iofopen.c (__fopen_maybe_mmap): Don't try to mmap here.
	If the stream is read-only, set its jump tables to those new ones.
	* libio/iofdopen.c (_IO_new_fdopen) [_G_HAVE_MMAP]: Set the initial
	jump tables to the maybe_mmap ones, and don't call __fopen_maybe_mmap.
	We need the tables set before _IO_file_attach.

	* libio/tst-mmap-eofsync.c: New file.
	* libio/tst-mmap-fflushsync.c: New file.
	* libio/bug-mmap-fflush.c: New file.
	* libio/tst-mmap2-eofsync.c: New file.
	* libio/Makefile (tests): Add them.

	* libio/wfileops.c (_IO_wfile_underflow_mmap): Don't set EOF bit when
	_IO_file_underflow_mmap fails, it already set the appropriate bit.

libio/tst-mmap2-eofsync.c

@@ -0,0 +1,137 @@
+/* Test program for synchronization of stdio state with file after EOF.  */
+
+#include <stdio.h>
+#include <error.h>
+#include <errno.h>
+#include <string.h>
+#include <unistd.h>
+
+static void do_prepare (void);
+#define PREPARE(argc, argv) do_prepare ()
+static int do_test (void);
+#define TEST_FUNCTION do_test ()
+#include <test-skeleton.c>
+
+static char *temp_file;
+static int temp_fd;
+
+static char *pages;
+
+static void
+do_prepare (void)
+{
+  pages = malloc (getpagesize () * 2);
+  memset (pages, 'a', getpagesize ());
+  memset (pages + getpagesize (), 'b', getpagesize ());
+
+  temp_fd = create_temp_file ("tst-mmap2-eofsync.", &temp_file);
+  if (temp_fd == -1)
+    error (1, errno, "cannot create temporary file");
+  else
+    {
+      ssize_t cc = write (temp_fd, pages, getpagesize ());
+      if (cc != getpagesize ())
+	error (1, errno, "cannot write to temporary file");
+    }
+}
+
+static int
+do_test (void)
+{
+  const size_t pagesize = getpagesize ();
+  FILE *f;
+  char buf[pagesize];
+  int result = 0;
+  int c;
+
+  f = fopen (temp_file, "r");
+  if (f == NULL)
+    {
+      perror (temp_file);
+      return 1;
+    }
+
+  if (fread (buf, pagesize, 1, f) != 1)
+    {
+      perror ("fread");
+      return 1;
+    }
+
+  if (memcmp (buf, pages, pagesize))
+    {
+      puts ("data mismatch in page 1");
+      result = 1;
+    }
+
+  printf ("feof = %d, ferror = %d immediately after fread\n",
+	  feof (f), ferror (f));
+
+  c = fgetc (f);
+  if (c == EOF)
+    printf ("fgetc -> EOF (feof = %d, ferror = %d)\n",
+	    feof (f), ferror (f));
+  else
+    {
+      printf ("fgetc returned %o (feof = %d, ferror = %d)\n",
+	      c, feof (f), ferror (f));
+      result = 1;
+    }
+
+  c = write (temp_fd, pages + pagesize, pagesize);
+  if (c == pagesize)
+    printf ("wrote more to file\n");
+  else
+    {
+      printf ("wrote %d != %d (%m)\n", c, pagesize);
+      result = 1;
+    }
+
+  if (fread (buf, pagesize, 1, f) != 1)
+    {
+      printf ("second fread fails: feof = %d, ferror = %d (%m)\n",
+	      feof (f), ferror (f));
+      clearerr (f);
+      if (fread (buf, pagesize, 1, f) != 1)
+	{
+	  printf ("retry fread fails: feof = %d, ferror = %d (%m)\n",
+		  feof (f), ferror (f));
+	  result = 1;
+	}
+    }
+  if (result == 0 && memcmp (buf, pages + pagesize, pagesize))
+    {
+      puts ("data mismatch in page 2");
+      result = 1;
+    }
+
+  fseek (f, pagesize - 1, SEEK_SET);
+  c = fgetc (f);
+  if (c != 'a')
+    {
+      printf ("fgetc at end of page 1 read '%c' (%m)\n", c);
+      result = 1;
+    }
+
+  if (ftruncate (temp_fd, pagesize) < 0)
+    {
+      printf ("ftruncate failed: %m\n");
+      result = 1;
+    }
+
+  fflush (f);
+
+  c = fgetc (f);
+  if (c == EOF)
+    printf ("after truncate fgetc -> EOF (feof = %d, ferror = %d)\n",
+	    feof (f), ferror (f));
+  else
+    {
+      printf ("after truncate fgetc returned '%c' (feof = %d, ferror = %d)\n",
+	      c, feof (f), ferror (f));
+      result = 1;
+    }
+
+  fclose (f);
+
+  return result;
+}