Use unlocked stdio more systematically

This can improve performance significantly on stdio-bottlenecked code.
E.g., make-docfile is 3x faster on my Fedora 25 x86-64 desktop.
* admin/merge-gnulib (GNULIB_MODULES): Add unlocked-io.
* lib-src/ebrowse.c, lib-src/emacsclient.c, lib-src/etags.c:
* lib-src/hexl.c, lib-src/make-docfile.c, lib-src/movemail.c:
* lib-src/profile.c, lib-src/update-game-score.c:
Include unlocked-io.h instead of stdio.h, since these programs are
single-threaded.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.
* lib/unlocked-io.h, m4/unlocked-io.m4: New files, copied from Gnulib.
* src/charset.c, src/cm.c, src/emacs.c, src/image.c, src/keyboard.c:
* src/lread.c, src/term.c:
Include sysstdio.h, possibly instead of stdio.h, to define
the unlocked functions if the system does not provide them.
* src/charset.c, src/lread.c (getc_unlocked):
Remove, since sysstdio.h now defines it if needed.
* src/cm.c (cmputc, cmcheckmagic):
* src/dispnew.c (update_frame, update_frame_with_menu)
(update_frame_1, Fsend_string_to_terminal, Fding, bitch_at_user):
* src/emacs.c (main, Fdump_emacs):
* src/fileio.c (Fdo_auto_save, Fset_binary_mode):
* src/image.c (slurp_file, png_read_from_file, png_load_body)
(our_stdio_fill_input_buffer):
* src/keyboard.c (record_char, kbd_buffer_get_event, handle_interrupt):
* src/lread.c (readbyte_from_file):
* src/minibuf.c (read_minibuf_noninteractive):
* src/print.c (printchar_to_stream, strout)
(Fredirect_debugging_output):
* src/sysdep.c (reset_sys_modes, procfs_ttyname)
(procfs_get_total_memory):
* src/term.c (tty_ring_bell, tty_send_additional_strings)
(tty_set_terminal_modes, tty_reset_terminal_modes)
(tty_update_end, tty_clear_end_of_line, tty_write_glyphs)
(tty_write_glyphs_with_face, tty_insert_glyphs)
(tty_menu_activate):
* src/xfaces.c (Fx_load_color_file):
Use unlocked stdio when it should be safe.
* src/sysstdio.h (clearerr_unlocked, feof_unlocked, ferror_unlocked)
(fflush_unlocked, fgets_unlocked, fputc_unlocked, fputs_unlocked)
(fread_unlocked, fwrite_unlocked, getc_unlocked, getchar_unlocked)
(putc_unlocked, putchar_unloced): Provide substitutes if not declared.

14 files changed, 130 insertions, 100 deletions

diff --git a/src/charset.c b/src/charset.c
index 9d15375dd79..d0840f7d2a9 100644
--- a/src/charset.c
+++ b/src/charset.c
@@ -29,7 +29,6 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include <config.h>
 
 #include <errno.h>
-#include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <limits.h>
@@ -40,6 +39,7 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include "charset.h"
 #include "coding.h"
 #include "buffer.h"
+#include "sysstdio.h"
 
 /*** GENERAL NOTES on CODED CHARACTER SETS (CHARSETS) ***
 
@@ -198,10 +198,6 @@ static struct
 
 #define GET_TEMP_CHARSET_WORK_DECODER(CODE)     \
   (temp_charset_work->table.decoder[(CODE)])
-
-#ifndef HAVE_GETC_UNLOCKED
-#define getc_unlocked getc
-#endif
 
 
 /* Set to 1 to warn that a charset map is loaded and thus a buffer
diff --git a/src/cm.c b/src/cm.c
index efa50b0f58d..9a90f37445c 100644
--- a/src/cm.c
+++ b/src/cm.c
@@ -19,10 +19,10 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
 
 #include <config.h>
-#include <stdio.h>
 
 #include "lisp.h"
 #include "cm.h"
+#include "sysstdio.h"
 #include "termchar.h"
 #include "tparam.h"
 
@@ -45,8 +45,8 @@ int
 cmputc (int c)
 {
   if (current_tty->termscript)
-    putc (c & 0177, current_tty->termscript);
-  putc (c & 0177, current_tty->output);
+    putc_unlocked (c & 0177, current_tty->termscript);
+  putc_unlocked (c & 0177, current_tty->output);
   return c;
 }
 
@@ -117,11 +117,11 @@ cmcheckmagic (struct tty_display_info *tty)
       if (!MagicWrap (tty) || curY (tty) >= FrameRows (tty) - 1)
         emacs_abort ();
       if (tty->termscript)
-        putc ('\r', tty->termscript);
-      putc ('\r', tty->output);
+        putc_unlocked ('\r', tty->termscript);
+      putc_unlocked ('\r', tty->output);
       if (tty->termscript)
-        putc ('\n', tty->termscript);
-      putc ('\n', tty->output);
+        putc_unlocked ('\n', tty->termscript);
+      putc_unlocked ('\n', tty->output);
       curX (tty) = 0;
       curY (tty)++;
     }
diff --git a/src/dispnew.c b/src/dispnew.c
index 27c69bde831..925e44d9804 100644
--- a/src/dispnew.c
+++ b/src/dispnew.c
@@ -3126,9 +3126,9 @@ update_frame (struct frame *f, bool force_p, bool inhibit_hairy_id_p)
       if (FRAME_TERMCAP_P (f) || FRAME_MSDOS_P (f))
         {
           if (FRAME_TTY (f)->termscript)
-            fflush (FRAME_TTY (f)->termscript);
+            fflush_unlocked (FRAME_TTY (f)->termscript);
           if (FRAME_TERMCAP_P (f))
-            fflush (FRAME_TTY (f)->output);
+            fflush_unlocked (FRAME_TTY (f)->output);
         }
 
       /* Check window matrices for lost pointers.  */
@@ -3181,8 +3181,8 @@ update_frame_with_menu (struct frame *f, int row, int col)
   update_end (f);
 
   if (FRAME_TTY (f)->termscript)
-    fflush (FRAME_TTY (f)->termscript);
-  fflush (FRAME_TTY (f)->output);
+    fflush_unlocked (FRAME_TTY (f)->termscript);
+  fflush_unlocked (FRAME_TTY (f)->output);
   /* Check window matrices for lost pointers.  */
 #if GLYPH_DEBUG
 #if 0
@@ -4531,7 +4531,7 @@ update_frame_1 (struct frame *f, bool force_p, bool inhibit_id_p,
                   ptrdiff_t outq = __fpending (display_output);
                   if (outq > 900
                       || (outq > 20 && ((i - 1) % preempt_count == 0)))
-                    fflush (display_output);
+                    fflush_unlocked (display_output);
                 }
             }
 
@@ -5615,13 +5615,13 @@ when TERMINAL is nil.  */)
 
       if (tty->termscript)
         {
-          fwrite (SDATA (string), 1, SBYTES (string), tty->termscript);
-          fflush (tty->termscript);
+          fwrite_unlocked (SDATA (string), 1, SBYTES (string), tty->termscript);
+          fflush_unlocked (tty->termscript);
         }
       out = tty->output;
     }
-  fwrite (SDATA (string), 1, SBYTES (string), out);
-  fflush (out);
+  fwrite_unlocked (SDATA (string), 1, SBYTES (string), out);
+  fflush_unlocked (out);
   unblock_input ();
   return Qnil;
 }
@@ -5636,7 +5636,7 @@ terminate any keyboard macro currently executing.  */)
   if (!NILP (arg))
     {
       if (noninteractive)
-        putchar (07);
+        putchar_unlocked (07);
       else
         ring_bell (XFRAME (selected_frame));
     }
@@ -5650,7 +5650,7 @@ void
 bitch_at_user (void)
 {
   if (noninteractive)
-    putchar (07);
+    putchar_unlocked (07);
   else if (!INTERACTIVE)  /* Stop executing a keyboard macro.  */
     {
       const char *msg
diff --git a/src/emacs.c b/src/emacs.c
index da8df1bf1c7..0fec7167588 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -23,7 +23,6 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include <errno.h>
 #include <fcntl.h>
-#include <stdio.h>
 #include <stdlib.h>
 
 #include <sys/file.h>
@@ -33,6 +32,7 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #define MAIN_PROGRAM
 #include "lisp.h"
+#include "sysstdio.h"
 
 #ifdef WINDOWSNT
 #include <fcntl.h>
@@ -885,7 +885,7 @@ main (int argc, char **argv)
     }
 #endif /* HAVE_SETRLIMIT and RLIMIT_STACK and not CYGWIN */
 
-  clearerr (stdin);
+  clearerr_unlocked (stdin);
 
   emacs_backtrace (-1);
 
@@ -983,7 +983,7 @@ main (int argc, char **argv)
       int i;
       printf ("Usage: %s [OPTION-OR-FILENAME]...\n", argv[0]);
       for (i = 0; i < ARRAYELTS (usage_message); i++)
-        fputs (usage_message[i], stdout);
+        fputs_unlocked (usage_message[i], stdout);
       exit (0);
     }
 
@@ -2197,7 +2197,7 @@ You must run Emacs in batch mode in order to dump it.  */)
   }
 #endif
 
-  fflush (stdout);
+  fflush_unlocked (stdout);
   /* Tell malloc where start of impure now is.  */
   /* Also arrange for warnings when nearly out of space.  */
 #if !defined SYSTEM_MALLOC && !defined HYBRID_MALLOC
diff --git a/src/fileio.c b/src/fileio.c
index cb070029a9b..a57d50b24e0 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -5643,14 +5643,12 @@ A non-nil CURRENT-ONLY argument means save only current buffer.  */)
           {
             block_input ();
             if (!NILP (BVAR (b, filename)))
-              {
-                fwrite (SDATA (BVAR (b, filename)), 1,
-                        SBYTES (BVAR (b, filename)), stream);
-              }
-            putc ('\n', stream);
-            fwrite (SDATA (BVAR (b, auto_save_file_name)), 1,
-                    SBYTES (BVAR (b, auto_save_file_name)), stream);
-            putc ('\n', stream);
+              fwrite_unlocked (SDATA (BVAR (b, filename)), 1,
+                               SBYTES (BVAR (b, filename)), stream);
+            putc_unlocked ('\n', stream);
+            fwrite_unlocked (SDATA (BVAR (b, auto_save_file_name)), 1,
+                             SBYTES (BVAR (b, auto_save_file_name)), stream);
+            putc_unlocked ('\n', stream);
             unblock_input ();
           }
 
@@ -5841,7 +5839,7 @@ effect except for flushing STREAM's data.  */)
 
   binmode = NILP (mode) ? O_TEXT : O_BINARY;
   if (fp != stdin)
-    fflush (fp);
+    fflush_unlocked (fp);
 
   return (set_binary_mode (fileno (fp), binmode) == O_BINARY) ? Qt : Qnil;
 }
diff --git a/src/image.c b/src/image.c
index aedec7954ee..07c4769e9e3 100644
--- a/src/image.c
+++ b/src/image.c
@@ -20,7 +20,6 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include <config.h>
 
 #include <fcntl.h>
-#include <stdio.h>
 #include <unistd.h>
 
 /* Include this before including <setjmp.h> to work around bugs with
@@ -41,6 +40,7 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include "buffer.h"
 #include "dispextern.h"
 #include "blockinput.h"
+#include "sysstdio.h"
 #include "systime.h"
 #include <epaths.h>
 #include "coding.h"
@@ -2361,7 +2361,7 @@ slurp_file (int fd, ptrdiff_t *size)
              This can happen if the file grows as we read it.  */
           ptrdiff_t buflen = st.st_size;
           buf = xmalloc (buflen + 1);
-          if (fread (buf, 1, buflen + 1, fp) == buflen)
+          if (fread_unlocked (buf, 1, buflen + 1, fp) == buflen)
             *size = buflen;
           else
             {
@@ -5890,7 +5890,7 @@ png_read_from_file (png_structp png_ptr, png_bytep data, png_size_t length)
 {
   FILE *fp = png_get_io_ptr (png_ptr);
 
-  if (fread (data, 1, length, fp) < length)
+  if (fread_unlocked (data, 1, length, fp) < length)
     png_error (png_ptr, "Read error");
 }
 
@@ -5959,7 +5959,7 @@ png_load_body (struct frame *f, struct image *img, struct png_load_context *c)
         }
 
       /* Check PNG signature.  */
-      if (fread (sig, 1, sizeof sig, fp) != sizeof sig
+      if (fread_unlocked (sig, 1, sizeof sig, fp) != sizeof sig
           || png_sig_cmp (sig, 0, sizeof sig))
         {
           fclose (fp);
@@ -6598,7 +6598,8 @@ our_stdio_fill_input_buffer (j_decompress_ptr cinfo)
     {
       ptrdiff_t bytes;
 
-      bytes = fread (src->buffer, 1, JPEG_STDIO_BUFFER_SIZE, src->file);
+      bytes = fread_unlocked (src->buffer, 1, JPEG_STDIO_BUFFER_SIZE,
+                              src->file);
       if (bytes > 0)
         src->mgr.bytes_in_buffer = bytes;
       else
diff --git a/src/keyboard.c b/src/keyboard.c
index 55486c6d9ab..3442b18409a 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -39,6 +39,7 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include "intervals.h"
 #include "keymap.h"
 #include "blockinput.h"
+#include "sysstdio.h"
 #include "systime.h"
 #include "atimer.h"
 #include "process.h"
@@ -3290,7 +3291,7 @@ record_char (Lisp_Object c)
       if (INTEGERP (c))
         {
           if (XUINT (c) < 0x100)
-            putc (XUINT (c), dribble);
+            putc_unlocked (XUINT (c), dribble);
           else
             fprintf (dribble, " 0x%"pI"x", XUINT (c));
         }
@@ -3303,15 +3304,15 @@ record_char (Lisp_Object c)
 
           if (SYMBOLP (dribblee))
             {
-              putc ('<', dribble);
-              fwrite (SDATA (SYMBOL_NAME (dribblee)), sizeof (char),
-                      SBYTES (SYMBOL_NAME (dribblee)),
-                      dribble);
-              putc ('>', dribble);
+              putc_unlocked ('<', dribble);
+              fwrite_unlocked (SDATA (SYMBOL_NAME (dribblee)), sizeof (char),
+                               SBYTES (SYMBOL_NAME (dribblee)),
+                               dribble);
+              putc_unlocked ('>', dribble);
             }
         }
 
-      fflush (dribble);
+      fflush_unlocked (dribble);
       unblock_input ();
     }
 }
@@ -3769,7 +3770,7 @@ kbd_buffer_get_event (KBOARD **kbp,
          detaching from the terminal.  */
       || (IS_DAEMON && DAEMON_RUNNING))
     {
-      int c = getchar ();
+      int c = getchar_unlocked ();
       XSETINT (obj, c);
       *kbp = current_kboard;
       return obj;
@@ -10377,7 +10378,7 @@ handle_interrupt (bool in_signal_handler)
           sigemptyset (&blocked);
           sigaddset (&blocked, SIGINT);
           pthread_sigmask (SIG_BLOCK, &blocked, 0);
-          fflush (stdout);
+          fflush_unlocked (stdout);
         }
 
       reset_all_sys_modes ();
diff --git a/src/lread.c b/src/lread.c
index 8716b86e9bf..182f96223a5 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -72,10 +72,6 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #define file_tell ftell
 #endif
 
-#ifndef HAVE_GETC_UNLOCKED
-#define getc_unlocked getc
-#endif
-
 /* The objects or placeholders read with the #n=object form.
 
    A hash table maps a number to either a placeholder (while the
@@ -474,16 +470,15 @@ readbyte_from_file (int c, Lisp_Object readcharfun)
     }
 
   block_input ();
-  c = getc_unlocked (instream);
 
   /* Interrupted reads have been observed while reading over the network.  */
-  while (c == EOF && ferror (instream) && errno == EINTR)
+  while ((c = getc_unlocked (instream)) == EOF && errno == EINTR
+         && ferror_unlocked (instream))
     {
       unblock_input ();
       maybe_quit ();
       block_input ();
-      clearerr (instream);
-      c = getc_unlocked (instream);
+      clearerr_unlocked (instream);
     }
 
   unblock_input ();
diff --git a/src/minibuf.c b/src/minibuf.c
index 1bbe276776e..835992fa79d 100644
--- a/src/minibuf.c
+++ b/src/minibuf.c
@@ -20,7 +20,6 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include <config.h>
 #include <errno.h>
-#include <stdio.h>
 
 #include <binary-io.h>
 
@@ -31,6 +30,7 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include "frame.h"
 #include "window.h"
 #include "keymap.h"
+#include "sysstdio.h"
 #include "systty.h"
 
 /* List of buffers for use as minibuffers.
@@ -209,15 +209,15 @@ read_minibuf_noninteractive (Lisp_Object map, Lisp_Object initial,
       suppress_echo_on_tty (STDIN_FILENO);
     }
 
-  fwrite (SDATA (prompt), 1, SBYTES (prompt), stdout);
-  fflush (stdout);
+  fwrite_unlocked (SDATA (prompt), 1, SBYTES (prompt), stdout);
+  fflush_unlocked (stdout);
 
   val = Qnil;
   size = 100;
   len = 0;
   line = xmalloc (size);
 
-  while ((c = getchar ()) != '\n' && c != '\r')
+  while ((c = getchar_unlocked ()) != '\n' && c != '\r')
     {
       if (c == EOF)
         {
diff --git a/src/print.c b/src/print.c
index aaec5b04956..6bf8af9ef93 100644
--- a/src/print.c
+++ b/src/print.c
@@ -228,7 +228,7 @@ printchar_to_stream (unsigned int ch, FILE *stream)
     {
       if (ASCII_CHAR_P (ch))
         {
-          putc (ch, stream);
+          putc_unlocked (ch, stream);
 #ifdef WINDOWSNT
           /* Send the output to a debugger (nothing happens if there
              isn't one).  */
@@ -246,7 +246,7 @@ printchar_to_stream (unsigned int ch, FILE *stream)
           if (encode_p)
             encoded_ch = code_convert_string_norecord (encoded_ch,
                                                        coding_system, true);
-          fwrite (SSDATA (encoded_ch), 1, SBYTES (encoded_ch), stream);
+          fwrite_unlocked (SSDATA (encoded_ch), 1, SBYTES (encoded_ch), stream);
 #ifdef WINDOWSNT
           if (print_output_debug_flag && stream == stderr)
             OutputDebugString (SSDATA (encoded_ch));
@@ -298,7 +298,7 @@ printchar (unsigned int ch, Lisp_Object fun)
           if (DISP_TABLE_P (Vstandard_display_table))
             printchar_to_stream (ch, stdout);
           else
-            fwrite (str, 1, len, stdout);
+            fwrite_unlocked (str, 1, len, stdout);
           noninteractive_need_newline = 1;
         }
       else
@@ -350,7 +350,7 @@ strout (const char *ptr, ptrdiff_t size, ptrdiff_t size_byte,
             }
         }
       else
-        fwrite (ptr, 1, size_byte, stdout);
+        fwrite_unlocked (ptr, 1, size_byte, stdout);
 
       noninteractive_need_newline = 1;
     }
@@ -801,7 +801,7 @@ append to existing target file.  */)
         report_file_error ("Cannot open debugging output stream", file);
     }
 
-  fflush (stderr);
+  fflush_unlocked (stderr);
   if (dup2 (fd, STDERR_FILENO) < 0)
     report_file_error ("dup2", file);
   if (fd != stderr_dup)
diff --git a/src/sysdep.c b/src/sysdep.c
index 70f4a9dd7ea..b52236769e0 100644
--- a/src/sysdep.c
+++ b/src/sysdep.c
@@ -1408,7 +1408,7 @@ reset_sys_modes (struct tty_display_info *tty_out)
 {
   if (noninteractive)
     {
-      fflush (stdout);
+      fflush_unlocked (stdout);
       return;
     }
   if (!tty_out->term_initted)
@@ -1428,17 +1428,14 @@ reset_sys_modes (struct tty_display_info *tty_out)
     }
   else
     {                   /* have to do it the hard way */
-      int i;
       tty_turn_off_insert (tty_out);
 
-      for (i = cursorX (tty_out); i < FrameCols (tty_out) - 1; i++)
-        {
-          fputc (' ', tty_out->output);
-        }
+      for (int i = cursorX (tty_out); i < FrameCols (tty_out) - 1; i++)
+        fputc_unlocked (' ', tty_out->output);
     }
 
   cmgoto (tty_out, FrameRows (tty_out) - 1, 0);
-  fflush (tty_out->output);
+  fflush_unlocked (tty_out->output);
 
   if (tty_out->terminal->reset_terminal_modes_hook)
     tty_out->terminal->reset_terminal_modes_hook (tty_out->terminal);
@@ -3079,7 +3076,7 @@ procfs_ttyname (int rdev)
       char minor[25];   /* 2 32-bit numbers + dash */
       char *endp;
 
-      for (; !feof (fdev) && !ferror (fdev); name[0] = 0)
+      for (; !feof_unlocked (fdev) && !ferror_unlocked (fdev); name[0] = 0)
         {
           if (fscanf (fdev, "%*s %s %u %s %*s\n", name, &major, minor) >= 3
               && major == MAJOR (rdev))
@@ -3129,7 +3126,7 @@ procfs_get_total_memory (void)
             break;
 
           case 0:
-            while ((c = getc (fmem)) != EOF && c != '\n')
+            while ((c = getc_unlocked (fmem)) != EOF && c != '\n')
               continue;
             done = c == EOF;
             break;
diff --git a/src/sysstdio.h b/src/sysstdio.h
index 45ee33f5580..7fbcefcdad9 100644
--- a/src/sysstdio.h
+++ b/src/sysstdio.h
@@ -33,4 +33,45 @@ extern FILE *emacs_fopen (char const *, char const *);
 # define FOPEN_TEXT ""
 #endif
 
+/* These are compatible with unlocked-io.h, if both files are included.  */
+#if !HAVE_DECL_CLEARERR_UNLOCKED
+# define clearerr_unlocked(x) clearerr (x)
+#endif
+#if !HAVE_DECL_FEOF_UNLOCKED
+# define feof_unlocked(x) feof (x)
+#endif
+#if !HAVE_DECL_FERROR_UNLOCKED
+# define ferror_unlocked(x) ferror (x)
+#endif
+#if !HAVE_DECL_FFLUSH_UNLOCKED
+# define fflush_unlocked(x) fflush (x)
+#endif
+#if !HAVE_DECL_FGETS_UNLOCKED
+# define fgets_unlocked(x,y,z) fgets (x,y,z)
+#endif
+#if !HAVE_DECL_FPUTC_UNLOCKED
+# define fputc_unlocked(x,y) fputc (x,y)
+#endif
+#if !HAVE_DECL_FPUTS_UNLOCKED
+# define fputs_unlocked(x,y) fputs (x,y)
+#endif
+#if !HAVE_DECL_FREAD_UNLOCKED
+# define fread_unlocked(w,x,y,z) fread (w,x,y,z)
+#endif
+#if !HAVE_DECL_FWRITE_UNLOCKED
+# define fwrite_unlocked(w,x,y,z) fwrite (w,x,y,z)
+#endif
+#if !HAVE_DECL_GETC_UNLOCKED
+# define getc_unlocked(x) getc (x)
+#endif
+#if !HAVE_DECL_GETCHAR_UNLOCKED
+# define getchar_unlocked() getchar ()
+#endif
+#if !HAVE_DECL_PUTC_UNLOCKED
+# define putc_unlocked(x,y) putc (x,y)
+#endif
+#if !HAVE_DECL_PUTCHAR_UNLOCKED
+# define putchar_unlocked(x) putchar (x)
+#endif
+
 #endif /* EMACS_SYSSTDIO_H */
diff --git a/src/term.c b/src/term.c
index 8770aff8a92..3d7f4ada0b9 100644
--- a/src/term.c
+++ b/src/term.c
@@ -22,7 +22,6 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include <config.h>
 #include <errno.h>
 #include <fcntl.h>
-#include <stdio.h>
 #include <stdlib.h>
 #include <sys/file.h>
 #include <sys/time.h>
@@ -45,6 +44,7 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include "keymap.h"
 #include "blockinput.h"
 #include "syssignal.h"
+#include "sysstdio.h"
 #ifdef MSDOS
 #include "msdos.h"
 static int been_here = -1;
@@ -146,7 +146,7 @@ tty_ring_bell (struct frame *f)
       OUTPUT (tty, (tty->TS_visible_bell && visible_bell
                     ? tty->TS_visible_bell
                     : tty->TS_bell));
-      fflush (tty->output);
+      fflush_unlocked (tty->output);
     }
 }
 
@@ -167,9 +167,10 @@ tty_send_additional_strings (struct terminal *terminal, Lisp_Object sym)
       Lisp_Object string = XCAR (extra_codes);
       if (STRINGP (string))
         {
-          fwrite (SDATA (string), 1, SBYTES (string), tty->output);
+          fwrite_unlocked (SDATA (string), 1, SBYTES (string), tty->output);
           if (tty->termscript)
-            fwrite (SDATA (string), 1, SBYTES (string), tty->termscript);
+            fwrite_unlocked (SDATA (string), 1, SBYTES (string),
+                             tty->termscript);
         }
     }
 }
@@ -197,7 +198,7 @@ tty_set_terminal_modes (struct terminal *terminal)
       OUTPUT_IF (tty, tty->TS_keypad_mode);
       losecursor (tty);
       tty_send_additional_strings (terminal, Qtty_mode_set_strings);
-      fflush (tty->output);
+      fflush_unlocked (tty->output);
     }
 }
 
@@ -220,7 +221,7 @@ tty_reset_terminal_modes (struct terminal *terminal)
       /* Output raw CR so kernel can track the cursor hpos.  */
       current_tty = tty;
       cmputc ('\r');
-      fflush (tty->output);
+      fflush_unlocked (tty->output);
     }
 }
 
@@ -235,7 +236,7 @@ tty_update_end (struct frame *f)
     tty_show_cursor (tty);
   tty_turn_off_insert (tty);
   tty_background_highlight (tty);
-  fflush (tty->output);
+  fflush_unlocked (tty->output);
 }
 
 /* The implementation of set_terminal_window for termcap frames. */
@@ -497,8 +498,8 @@ tty_clear_end_of_line (struct frame *f, int first_unused_hpos)
       for (i = curX (tty); i < first_unused_hpos; i++)
         {
           if (tty->termscript)
-            fputc (' ', tty->termscript);
-          fputc (' ', tty->output);
+            fputc_unlocked (' ', tty->termscript);
+          fputc_unlocked (' ', tty->output);
         }
       cmplus (tty, first_unused_hpos - curX (tty));
     }
@@ -771,11 +772,11 @@ tty_write_glyphs (struct frame *f, struct glyph *string, int len)
       if (coding->produced > 0)
         {
           block_input ();
-          fwrite (conversion_buffer, 1, coding->produced, tty->output);
-          if (ferror (tty->output))
-            clearerr (tty->output);
+          fwrite_unlocked (conversion_buffer, 1, coding->produced, tty->output);
+          clearerr_unlocked (tty->output);
           if (tty->termscript)
-            fwrite (conversion_buffer, 1, coding->produced, tty->termscript);
+            fwrite_unlocked (conversion_buffer, 1, coding->produced,
+                             tty->termscript);
           unblock_input ();
         }
       string += n;
@@ -832,11 +833,11 @@ tty_write_glyphs_with_face (register struct frame *f, register struct glyph *str
   if (coding->produced > 0)
     {
       block_input ();
-      fwrite (conversion_buffer, 1, coding->produced, tty->output);
-      if (ferror (tty->output))
-        clearerr (tty->output);
+      fwrite_unlocked (conversion_buffer, 1, coding->produced, tty->output);
+      clearerr_unlocked (tty->output);
       if (tty->termscript)
-        fwrite (conversion_buffer, 1, coding->produced, tty->termscript);
+        fwrite_unlocked (conversion_buffer, 1, coding->produced,
+                         tty->termscript);
       unblock_input ();
     }
 
@@ -918,11 +919,11 @@ tty_insert_glyphs (struct frame *f, struct glyph *start, int len)
       if (coding->produced > 0)
         {
           block_input ();
-          fwrite (conversion_buffer, 1, coding->produced, tty->output);
-          if (ferror (tty->output))
-            clearerr (tty->output);
+          fwrite_unlocked (conversion_buffer, 1, coding->produced, tty->output);
+          clearerr_unlocked (tty->output);
           if (tty->termscript)
-            fwrite (conversion_buffer, 1, coding->produced, tty->termscript);
+            fwrite_unlocked (conversion_buffer, 1, coding->produced,
+                             tty->termscript);
           unblock_input ();
         }
 
@@ -3327,7 +3328,7 @@ tty_menu_activate (tty_menu *menu, int *pane, int *selidx,
          which calls tty_show_cursor.  Re-hide it, so it doesn't show
          through the menus.  */
       tty_hide_cursor (tty);
-      fflush (tty->output);
+      fflush_unlocked (tty->output);
     }
 
   sf->mouse_moved = 0;
@@ -3335,7 +3336,7 @@ tty_menu_activate (tty_menu *menu, int *pane, int *selidx,
   while (statecount--)
     free_saved_screen (state[statecount].screen_behind);
   tty_show_cursor (tty);        /* Turn cursor back on.  */
-  fflush (tty->output);
+  fflush_unlocked (tty->output);
 
 /* Clean up any mouse events that are waiting inside Emacs event queue.
      These events are likely to be generated before the menu was even
diff --git a/src/xfaces.c b/src/xfaces.c
index 4714b7b3cb8..86bb9b0b496 100644
--- a/src/xfaces.c
+++ b/src/xfaces.c
@@ -6232,7 +6232,7 @@ where R,G,B are numbers between 0 and 255 and name is an arbitrary string.  */)
       int red, green, blue;
       int num;
 
-      while (fgets (buf, sizeof (buf), fp) != NULL) {
+      while (fgets_unlocked (buf, sizeof (buf), fp) != NULL) {
         if (sscanf (buf, "%d %d %d %n", &red, &green, &blue, &num) == 3)
           {
 #ifdef HAVE_NTGUI