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, 42 insertions, 2 deletions

diff --git a/lib/gnulib.mk.in b/lib/gnulib.mk.in
index b9a32d9dbc1..b4d510bd62e 100644
--- a/lib/gnulib.mk.in
+++ b/lib/gnulib.mk.in
@@ -136,6 +136,7 @@
 #  stddef \
 #  stdio \
 #  stpcpy \
+#  strnlen \
 #  strtoimax \
 #  symlink \
 #  sys_stat \
@@ -1075,7 +1076,6 @@ gl_GNULIB_ENABLED_getdtablesize = @gl_GNULIB_ENABLED_getdtablesize@
 gl_GNULIB_ENABLED_getgroups = @gl_GNULIB_ENABLED_getgroups@
 gl_GNULIB_ENABLED_malloca = @gl_GNULIB_ENABLED_malloca@
 gl_GNULIB_ENABLED_open = @gl_GNULIB_ENABLED_open@
-gl_GNULIB_ENABLED_pathmax = @gl_GNULIB_ENABLED_pathmax@
 gl_GNULIB_ENABLED_strtoll = @gl_GNULIB_ENABLED_strtoll@
 gl_LIBOBJS = @gl_LIBOBJS@
 gl_LTLIBOBJS = @gl_LTLIBOBJS@
@@ -1110,7 +1110,6 @@ pdfdir = @pdfdir@
 prefix = @prefix@
 program_transform_name = @program_transform_name@
 psdir = @psdir@
-runstatedir = @runstatedir@
 sbindir = @sbindir@
 sharedstatedir = @sharedstatedir@
 srcdir = @srcdir@
@@ -2811,6 +2810,17 @@ EXTRA_DIST += string.in.h
 endif
 ## end   gnulib module string
 
+## begin gnulib module strnlen
+ifeq (,$(OMIT_GNULIB_MODULE_strnlen))
+
+
+EXTRA_DIST += strnlen.c
+
+EXTRA_libgnu_a_SOURCES += strnlen.c
+
+endif
+## end   gnulib module strnlen
+
 ## begin gnulib module strtoimax
 ifeq (,$(OMIT_GNULIB_MODULE_strtoimax))
 
diff --git a/lib/strnlen.c b/lib/strnlen.c
new file mode 100644
index 00000000000..9fb663509a0
--- /dev/null
+++ b/lib/strnlen.c
@@ -0,0 +1,30 @@
+/* Find the length of STRING, but scan at most MAXLEN characters.
+   Copyright (C) 2005-2007, 2009-2019 Free Software Foundation, Inc.
+   Written by Simon Josefsson.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+#include <string.h>
+
+/* Find the length of STRING, but scan at most MAXLEN characters.
+   If no '\0' terminator is found in that many characters, return MAXLEN.  */
+
+size_t
+strnlen (const char *string, size_t maxlen)
+{
+  const char *end = memchr (string, '\0', maxlen);
+  return end ? (size_t) (end - string) : maxlen;
+}