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.

11 files changed, 21 insertions, 29 deletions

diff --git a/src/doprnt.c b/src/doprnt.c
index 5fb70634048..64bb368ee3e 100644
--- a/src/doprnt.c
+++ b/src/doprnt.c
@@ -357,8 +357,8 @@ doprnt (char *buffer, ptrdiff_t bufsize, const char *format,
               if (fmtcpy[1] != 's')
                 minlen = atoi (&fmtcpy[1]);
               string = va_arg (ap, char *);
-              tem = strlen (string);
-              if (STRING_BYTES_BOUND < tem)
+              tem = strnlen (string, STRING_BYTES_BOUND + 1);
+              if (tem == STRING_BYTES_BOUND + 1)
                 error ("String for %%s or %%S format is too long");
               width = strwidth (string, tem);
               goto doit1;
diff --git a/src/emacs.c b/src/emacs.c
index 1ddd10b8051..231acc0ef32 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -1520,8 +1520,8 @@ Using an Emacs configured with --with-x-toolkit=lucid does not have this problem
               }
 
             /* In exec'd: parse special dname into pipe and name info. */
-            if (!dname_arg || !strchr (dname_arg, '\n')
-                || strlen (dname_arg) < 1 || strlen (dname_arg) > 70)
+            if (!dname_arg || !*dname_arg || strnlen (dname_arg, 71) == 71
+                || !strchr (dname_arg, '\n'))
           {
             fprintf (stderr, "emacs daemon: daemon name absent or too long\n");
             exit (EXIT_CANNOT_INVOKE);
diff --git a/src/inotify.c b/src/inotify.c
index 9a7dbb8f413..e8891aefc7a 100644
--- a/src/inotify.c
+++ b/src/inotify.c
@@ -181,8 +181,7 @@ inotifyevent_to_event (Lisp_Object watch, struct inotify_event const *ev)
 
   if (ev->len > 0)
     {
-      size_t const len = strlen (ev->name);
-      name = make_unibyte_string (ev->name, min (len, ev->len));
+      name = make_unibyte_string (ev->name, strnlen (ev->name, ev->len));
       name = DECODE_FILE (name);
     }
   else
diff --git a/src/json.c b/src/json.c
index e2a4424463b..23234c767d8 100644
--- a/src/json.c
+++ b/src/json.c
@@ -197,9 +197,7 @@ init_json (void)
 static bool
 json_has_prefix (const char *string, const char *prefix)
 {
-  size_t string_len = strlen (string);
-  size_t prefix_len = strlen (prefix);
-  return string_len >= prefix_len && memcmp (string, prefix, prefix_len) == 0;
+  return strncmp (string, prefix, strlen (prefix)) == 0;
 }
 
 /* Return whether STRING ends with SUFFIX.  */
diff --git a/src/keyboard.c b/src/keyboard.c
index 0d7f124f5f3..56916e0cb4e 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -7331,7 +7331,7 @@ menu_separator_name_p (const char *label)
 {
   if (!label)
     return 0;
-  else if (strlen (label) > 3
+  else if (strnlen (label, 4) == 4
            && memcmp (label, "--", 2) == 0
            && label[2] != '-')
     {
@@ -8248,13 +8248,13 @@ parse_tool_bar_item (Lisp_Object key, Lisp_Object item)
       Lisp_Object tcapt = PROP (TOOL_BAR_ITEM_CAPTION);
       const char *label = SYMBOLP (tkey) ? SSDATA (SYMBOL_NAME (tkey)) : "";
       const char *capt = STRINGP (tcapt) ? SSDATA (tcapt) : "";
-      ptrdiff_t max_lbl =
-        2 * max (0, min (tool_bar_max_label_size, STRING_BYTES_BOUND / 2));
-      char *buf = xmalloc (max_lbl + 1);
+      ptrdiff_t max_lbl_size =
+        2 * max (0, min (tool_bar_max_label_size, STRING_BYTES_BOUND / 2)) + 1;
+      char *buf = xmalloc (max_lbl_size);
       Lisp_Object new_lbl;
-      ptrdiff_t caption_len = strlen (capt);
+      ptrdiff_t caption_len = strnlen (capt, max_lbl_size);
 
-      if (caption_len <= max_lbl && capt[0] != '\0')
+      if (0 < caption_len && caption_len < max_lbl_size)
         {
           strcpy (buf, capt);
           while (caption_len > 0 && buf[caption_len - 1] == '.')
@@ -8263,7 +8263,8 @@ parse_tool_bar_item (Lisp_Object key, Lisp_Object item)
           label = capt = buf;
         }
 
-      if (strlen (label) <= max_lbl && label[0] != '\0')
+      ptrdiff_t label_len = strnlen (label, max_lbl_size);
+      if (0 < label_len && label_len < max_lbl_size)
         {
           ptrdiff_t j;
           if (label != buf)
diff --git a/src/nsmenu.m b/src/nsmenu.m
index 3fe06cda02a..817f8cff184 100644
--- a/src/nsmenu.m
+++ b/src/nsmenu.m
@@ -611,7 +611,7 @@ ns_activate_menubar (struct frame *f)
   const char *tpos = key;
   keyEquivModMask = NSEventModifierFlagCommand;
 
-  if (!key || !strlen (key))
+  if (!key || !*key)
     return @"";
 
   while (*tpos == ' ' || *tpos == '(')
diff --git a/src/nsterm.m b/src/nsterm.m
index 0ab03b46df1..8d46a49cc5e 100644
--- a/src/nsterm.m
+++ b/src/nsterm.m
@@ -9298,7 +9298,7 @@ ns_xlfd_to_fontname (const char *xlfd)
     sscanf (xlfd, "-%*[^-]-%179[^-]-", name);
 
   /* stopgap for malformed XLFD input */
-  if (strlen (name) == 0)
+  if (!*name)
     strcpy (name, "Monaco");
 
   /* undo hack in ns_fontname_to_xlfd, converting '$' to '-', '_' to ' '
diff --git a/src/process.c b/src/process.c
index 6717ccb4187..15d87cf6015 100644
--- a/src/process.c
+++ b/src/process.c
@@ -2857,11 +2857,7 @@ set_socket_option (int s, Lisp_Object opt, Lisp_Object val)
            This should work on all systems.   KFS. 2003-09-23.  */
         memset (devname, 0, sizeof devname);
         if (STRINGP (val))
-          {
-            char *arg = SSDATA (val);
-            int len = min (strlen (arg), IFNAMSIZ);
-            memcpy (devname, arg, len);
-          }
+          memcpy (devname, SDATA (val), min (SBYTES (val), IFNAMSIZ));
         else if (!NILP (val))
           error ("Bad option value for %s", name);
         ret = setsockopt (s, sopt->optlevel, sopt->optnum,
diff --git a/src/sysdep.c b/src/sysdep.c
index 0910b69f8bc..b702bae5818 100644
--- a/src/sysdep.c
+++ b/src/sysdep.c
@@ -281,7 +281,7 @@ get_current_dir_name_or_unreachable (void)
       pwd = get_current_dir_name ();
       if (pwd)
         {
-          if (strlen (pwd) < dirsize_max)
+          if (strnlen (pwd, dirsize_max) < dirsize_max)
             return pwd;
           free (pwd);
           errno = ERANGE;
@@ -298,7 +298,7 @@ get_current_dir_name_or_unreachable (void)
      sometimes a nicer name, and using it may avoid a fatal error if a
      parent directory is searchable but not readable.  */
   if (pwd
-      && (pwdlen = strlen (pwd)) < bufsize_max
+      && (pwdlen = strnlen (pwd, bufsize_max)) < bufsize_max
       && IS_DIRECTORY_SEP (pwd[pwdlen && IS_DEVICE_SEP (pwd[1]) ? 2 : 0])
       && stat (pwd, &pwdstat) == 0
       && stat (".", &dotstat) == 0
diff --git a/src/term.c b/src/term.c
index ce06e1cd4e5..8b5a710d80a 100644
--- a/src/term.c
+++ b/src/term.c
@@ -4400,7 +4400,7 @@ vfatal (const char *str, va_list ap)
 {
   fprintf (stderr, "emacs: ");
   vfprintf (stderr, str, ap);
-  if (!(strlen (str) > 0 && str[strlen (str) - 1] == '\n'))
+  if (! (str[0] && str[strlen (str) - 1] == '\n'))
     fprintf (stderr, "\n");
   exit (1);
 }
diff --git a/src/xdisp.c b/src/xdisp.c
index 25e8932945e..9f63ef4b180 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -24341,9 +24341,7 @@ store_mode_line_string (const char *string, Lisp_Object lisp_string,
 
   if (string != NULL)
     {
-      len = strlen (string);
-      if (precision > 0 && len > precision)
-        len = precision;
+      len = strnlen (string, precision <= 0 ? SIZE_MAX : precision);
       lisp_string = make_string (string, len);
       if (NILP (props))
         props = mode_line_string_face_prop;