Avoid some strlen work, primarily via strnlen

* admin/merge-gnulib (GNULIB_MODULES): Add strnlen.
* lib-src/etags.c (find_entries):
* src/emacs.c (main):
* src/nsmenu.m (parseKeyEquiv:):
* src/nsterm.m (ns_xlfd_to_fontname):
* src/term.c (vfatal):
Prefer !*X to !strlen (X).
* lib-src/etags.c (pfnote, add_regex):
* lib-src/pop.c (pop_open):
* lib-src/update-game-score.c (main):
* lwlib/lwlib.c (lw_separator_p):
* src/doprnt.c (doprnt):
* src/emacs.c (main):
* src/inotify.c (inotifyevent_to_event):
* src/keyboard.c (menu_separator_name_p, parse_tool_bar_item):
* src/sysdep.c (get_current_dir_name_or_unreachable):
* src/xdisp.c (store_mode_line_string):
Use strnlen to avoid unnecessary work with strlen.
* lib-src/etags.c (Prolog_functions, prolog_pr)
(Erlang_functions, erlang_func):
Prefer ptrdiff_t to size_t when either will do.
(prolog_pr, erlang_func): New arg LASTLEN, to avoid
unnecessary strlen call. All callers changed.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.
* lib/strnlen.c, m4/strnlen.m4: New files, copied from Gnulib.
* lwlib/lwlib.c (lw_separator_p):
* src/json.c (json_has_prefix):
Use strncmp to avoid unecessary work with strlen + memcmp.
* src/process.c (set_socket_option): Use SBYTES instead of strlen.

2 files changed, 39 insertions, 0 deletions

diff --git a/m4/gnulib-comp.m4 b/m4/gnulib-comp.m4
index cb6dce15ccf..7e724fe3c4e 100644
--- a/m4/gnulib-comp.m4
+++ b/m4/gnulib-comp.m4
@@ -154,6 +154,7 @@ AC_DEFUN([gl_EARLY],
   # Code from module stdlib:
   # Code from module stpcpy:
   # Code from module string:
+  # Code from module strnlen:
   # Code from module strtoimax:
   # Code from module strtoll:
   # Code from module symlink:
@@ -403,6 +404,12 @@ AC_DEFUN([gl_INIT],
   fi
   gl_STRING_MODULE_INDICATOR([stpcpy])
   gl_HEADER_STRING_H
+  gl_FUNC_STRNLEN
+  if test $HAVE_DECL_STRNLEN = 0 || test $REPLACE_STRNLEN = 1; then
+    AC_LIBOBJ([strnlen])
+    gl_PREREQ_STRNLEN
+  fi
+  gl_STRING_MODULE_INDICATOR([strnlen])
   gl_FUNC_STRTOIMAX
   if test $HAVE_DECL_STRTOIMAX = 0 || test $REPLACE_STRTOIMAX = 1; then
     AC_LIBOBJ([strtoimax])
@@ -1003,6 +1010,7 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/str-two-way.h
   lib/strftime.h
   lib/string.in.h
+  lib/strnlen.c
   lib/strtoimax.c
   lib/strtol.c
   lib/strtoll.c
@@ -1131,6 +1139,7 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/stdlib_h.m4
   m4/stpcpy.m4
   m4/string_h.m4
+  m4/strnlen.m4
   m4/strtoimax.m4
   m4/strtoll.m4
   m4/symlink.m4
diff --git a/m4/strnlen.m4 b/m4/strnlen.m4
new file mode 100644
index 00000000000..c283c3ece9f
--- /dev/null
+++ b/m4/strnlen.m4
@@ -0,0 +1,30 @@
+# strnlen.m4 serial 13
+dnl Copyright (C) 2002-2003, 2005-2007, 2009-2019 Free Software Foundation,
+dnl Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_STRNLEN],
+[
+  AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
+
+  dnl Persuade glibc <string.h> to declare strnlen().
+  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+
+  AC_CHECK_DECLS_ONCE([strnlen])
+  if test $ac_cv_have_decl_strnlen = no; then
+    HAVE_DECL_STRNLEN=0
+  else
+    m4_pushdef([AC_LIBOBJ], [:])
+    dnl Note: AC_FUNC_STRNLEN does AC_LIBOBJ([strnlen]).
+    AC_FUNC_STRNLEN
+    m4_popdef([AC_LIBOBJ])
+    if test $ac_cv_func_strnlen_working = no; then
+      REPLACE_STRNLEN=1
+    fi
+  fi
+])
+
+# Prerequisites of lib/strnlen.c.
+AC_DEFUN([gl_PREREQ_STRNLEN], [:])