Prefer stpcpy to strcat

* admin/merge-gnulib (GNULIB_MODULES): Add stpcpy.
* lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
* lib/stpcpy.c, m4/stpcpy.m4: New files, from gnulib.
* lib-src/ebrowse.c (sym_scope_1, operator_name, open_file):
* lib-src/emacsclient.c (get_server_config, set_local_socket)
(start_daemon_and_retry_set_socket):
* lib-src/etags.c (main, C_entries, relative_filename):
* lib-src/pop.c (sendline):
* lib-src/update-game-score.c (main):
* lwlib/xlwmenu.c (resource_widget_value):
* src/callproc.c (child_setup):
* src/dbusbind.c (xd_signature_cat):
* src/doc.c (get_doc_string, Fsnarf_documentation):
* src/editfns.c (Fuser_full_name):
* src/frame.c (xrdb_get_resource):
* src/gtkutil.c (xg_get_file_with_chooser):
* src/tparam.c (tparam1):
* src/xfns.c (xic_create_fontsetname):
* src/xrdb.c (gethomedir, get_user_db, get_environ_db):
* src/xsmfns.c (smc_save_yourself_CB):
Rewrite to avoid the need for strcat, typically by using stpcpy
and/or lispstpcpy.  strcat tends to be part of O(N**2) algorithms.
* src/doc.c (sibling_etc):
* src/xrdb.c (xdefaults):
Now a top-level static constant.

5 files changed, 55 insertions, 57 deletions

diff --git a/lib-src/ebrowse.c b/lib-src/ebrowse.c
index 29a88e85f02..b7431593c3e 100644
--- a/lib-src/ebrowse.c
+++ b/lib-src/ebrowse.c
@@ -1150,19 +1150,19 @@ sym_scope_1 (struct sym *p)
   if (*scope_buffer)
     {
       ensure_scope_buffer_room (3);
-      strcat (scope_buffer, "::");
+      strcpy (scope_buffer + scope_buffer_len, "::");
       scope_buffer_len += 2;
     }
 
   len = strlen (p->name);
   ensure_scope_buffer_room (len + 1);
-  strcat (scope_buffer, p->name);
+  strcpy (scope_buffer + scope_buffer_len, p->name);
   scope_buffer_len += len;
 
   if (HAS_FLAG (p->flags, F_TEMPLATE))
     {
       ensure_scope_buffer_room (3);
-      strcat (scope_buffer, "<>");
+      strcpy (scope_buffer + scope_buffer_len, "<>");
       scope_buffer_len += 2;
     }
 
@@ -2797,24 +2797,25 @@ operator_name (int *sc)
       s = token_string (LA1);
       MATCH ();
 
-      len = strlen (s) + 10;
+      ptrdiff_t slen = strlen (s);
+      len = slen + 10;
       if (len > id_size)
         {
           size_t new_size = max (len, 2 * id_size);
           id = (char *) xrealloc (id, new_size);
           id_size = new_size;
         }
-      strcpy (id, s);
+      char *z = stpcpy (id, s);
 
       /* Vector new or delete?  */
       if (LOOKING_AT ('['))
         {
-          strcat (id, "[");
+          z = stpcpy (z, "[");
           MATCH ();
 
           if (LOOKING_AT (']'))
             {
-              strcat (id, "]");
+              strcpy (z, "]");
               MATCH ();
             }
         }
@@ -2830,7 +2831,7 @@ operator_name (int *sc)
           id = (char *) xrealloc (id, new_size);
           id_size = new_size;
         }
-      strcpy (id, "operator");
+      char *z = stpcpy (id, "operator");
 
       /* Beware access declarations of the form "X::f;" Beware of
          `operator () ()'.  Yet another difficulty is found in
@@ -2842,14 +2843,16 @@ operator_name (int *sc)
           len += strlen (s) + 2;
           if (len > id_size)
             {
+              ptrdiff_t idlen = z - id;
               size_t new_size = max (len, 2 * id_size);
               id = (char *) xrealloc (id, new_size);
               id_size = new_size;
+              z = id + idlen;
             }
 
           if (*s != ')' && *s != ']')
-            strcat (id, " ");
-          strcat (id, s);
+            *z++ = ' ';
+          z = stpcpy (z, s);
           MATCH ();
 
           /* If this is a simple operator like `+', stop now.  */
@@ -3462,9 +3465,9 @@ open_file (char *file)
           buffer = (char *) xrealloc (buffer, buffer_size);
         }
 
-      strcpy (buffer, path->path);
-      strcat (buffer, "/");
-      strcat (buffer, file);
+      char *z = stpcpy (buffer, path->path);
+      *z++ = '/';
+      strcpy (z, file);
       fp = fopen (buffer, "r");
     }
 
diff --git a/lib-src/emacsclient.c b/lib-src/emacsclient.c
index ddc1b6de5e3..cfc321a1830 100644
--- a/lib-src/emacsclient.c
+++ b/lib-src/emacsclient.c
@@ -905,9 +905,9 @@ get_server_config (const char *config_file, struct sockaddr_in *server,
         {
           char *path = xmalloc (strlen (home) + strlen (config_file)
                                 + EXTRA_SPACE);
-          strcpy (path, home);
-          strcat (path, "/.emacs.d/server/");
-          strcat (path, config_file);
+          char *z = stpcpy (path, home);
+          z = stpcpy (z, "/.emacs.d/server/");
+          strcpy (z, config_file);
           config = fopen (path, "rb");
           free (path);
         }
@@ -916,9 +916,9 @@ get_server_config (const char *config_file, struct sockaddr_in *server,
         {
           char *path = xmalloc (strlen (home) + strlen (config_file)
                                 + EXTRA_SPACE);
-          strcpy (path, home);
-          strcat (path, "/.emacs.d/server/");
-          strcat (path, config_file);
+          char *z = stpcpy (path, home);
+          z = stpcpy (z, "/.emacs.d/server/");
+          strcpy (z, config_file);
           config = fopen (path, "rb");
           free (path);
         }
@@ -1193,7 +1193,6 @@ set_local_socket (const char *local_socket_name)
       {
         /* socket_name is a file name component.  */
         long uid = geteuid ();
-        ptrdiff_t tmpdirlen;
         use_tmpdir = 1;
         tmpdir = egetenv ("TMPDIR");
         if (!tmpdir)
@@ -1212,12 +1211,11 @@ set_local_socket (const char *local_socket_name)
 #endif
               tmpdir = "/tmp";
           }
-        tmpdirlen = strlen (tmpdir);
         socket_name_storage =
-          xmalloc (tmpdirlen + strlen (server_name) + EXTRA_SPACE);
-        strcpy (socket_name_storage, tmpdir);
-        sprintf (socket_name_storage + tmpdirlen, "/emacs%ld/", uid);
-        strcat (socket_name_storage + tmpdirlen, server_name);
+          xmalloc (strlen (tmpdir) + strlen (server_name) + EXTRA_SPACE);
+        char *z = stpcpy (socket_name_storage, tmpdir);
+        z += sprintf (z, "/emacs%ld/", uid);
+        strcpy (z, server_name);
         local_socket_name = socket_name_storage;
       }
 
@@ -1253,12 +1251,12 @@ set_local_socket (const char *local_socket_name)
               {
                 /* We're running under su, apparently. */
                 long uid = pw->pw_uid;
-                ptrdiff_t tmpdirlen = strlen (tmpdir);
                 char *user_socket_name
-                  = xmalloc (tmpdirlen + strlen (server_name) + EXTRA_SPACE);
-                strcpy (user_socket_name, tmpdir);
-                sprintf (user_socket_name + tmpdirlen, "/emacs%ld/", uid);
-                strcat (user_socket_name + tmpdirlen, server_name);
+                  = xmalloc (strlen (tmpdir) + strlen (server_name)
+                             + EXTRA_SPACE);
+                char *z = stpcpy (user_socket_name, tmpdir);
+                z += sprintf (z, "/emacs%ld/", uid);
+                strcpy (z, server_name);
 
                 if (strlen (user_socket_name) < sizeof (server.sun_path))
                   strcpy (server.sun_path, user_socket_name);
@@ -1507,8 +1505,7 @@ start_daemon_and_retry_set_socket (void)
           const char *deq = "--daemon=";
           char *daemon_arg = xmalloc (strlen (deq)
                                       + strlen (socket_name) + 1);
-          strcpy (daemon_arg, deq);
-          strcat (daemon_arg, socket_name);
+          strcpy (stpcpy (daemon_arg, deq), socket_name);
           d_argv[1] = daemon_arg;
         }
       execvp ("emacs", d_argv);
diff --git a/lib-src/etags.c b/lib-src/etags.c
index 6639ac4f235..78b3fed1128 100644
--- a/lib-src/etags.c
+++ b/lib-src/etags.c
@@ -1277,13 +1277,13 @@ main (int argc, char **argv)
             default:
               continue;         /* the for loop */
             }
-          strcpy (cmd, "mv ");
-          strcat (cmd, tagfile);
-          strcat (cmd, " OTAGS;fgrep -v '\t");
-          strcat (cmd, argbuffer[i].what);
-          strcat (cmd, "\t' OTAGS >");
-          strcat (cmd, tagfile);
-          strcat (cmd, ";rm OTAGS");
+          char *z = stpcpy (cmd, "mv ");
+          z = stpcpy (z, tagfile);
+          z = stpcpy (z, " OTAGS;fgrep -v '\t");
+          z = stpcpy (z, argbuffer[i].what);
+          z = stpcpy (z, "\t' OTAGS >");
+          z = stpcpy (z, tagfile);
+          strcpy (z, ";rm OTAGS");
           if (system (cmd) != EXIT_SUCCESS)
             fatal ("failed to execute shell command", (char *)NULL);
         }
@@ -1307,10 +1307,10 @@ main (int argc, char **argv)
         /* Maybe these should be used:
            setenv ("LC_COLLATE", "C", 1);
            setenv ("LC_ALL", "C", 1); */
-        strcpy (cmd, "sort -u -o ");
-        strcat (cmd, tagfile);
-        strcat (cmd, " ");
-        strcat (cmd, tagfile);
+        char *z = stpcpy (cmd, "sort -u -o ");
+        z = stpcpy (z, tagfile);
+        *z++ = ' ';
+        strcpy (z, tagfile);
         exit (system (cmd));
       }
   return EXIT_SUCCESS;
@@ -3427,8 +3427,9 @@ C_entries (int c_ext, FILE *inf)
             case omethodtag:
             case omethodparm:
               objdef = omethodcolon;
-              linebuffer_setlen (&token_name, token_name.len + 1);
-              strcat (token_name.buffer, ":");
+              int toklen = token_name.len;
+              linebuffer_setlen (&token_name, toklen + 1);
+              strcpy (token_name.buffer + toklen, ":");
               break;
             }
           if (structdef == stagseen)
@@ -6362,12 +6363,12 @@ relative_filename (char *file, char *dir)
   while ((dp = strchr (dp + 1, '/')) != NULL)
     i += 1;
   res = xnew (3*i + strlen (fp + 1) + 1, char);
-  res[0] = '\0';
+  char *z = res;
   while (i-- > 0)
-    strcat (res, "../");
+    z = stpcpy (z, "../");
 
   /* Add the file name relative to the common root of file and dir. */
-  strcat (res, fp + 1);
+  strcpy (z, fp + 1);
   free (afn);
 
   return res;
diff --git a/lib-src/pop.c b/lib-src/pop.c
index ffe16c5f911..70011504a34 100644
--- a/lib-src/pop.c
+++ b/lib-src/pop.c
@@ -1397,8 +1397,7 @@ sendline (popserver server, const char *line)
      over a few dozen messages, and is a big chunk of the time we
      spend fetching mail from a server close by.  */
   buf = alloca (strlen (line) + 3);
-  strcpy (buf, line);
-  strcat (buf, "\r\n");
+  strcpy (stpcpy (buf, line), "\r\n");
   ret = fullwrite (server->file, buf, strlen (buf));
 
   if (ret < 0)
diff --git a/lib-src/update-game-score.c b/lib-src/update-game-score.c
index 7a64cd04f47..b311001bd62 100644
--- a/lib-src/update-game-score.c
+++ b/lib-src/update-game-score.c
@@ -221,9 +221,9 @@ main (int argc, char **argv)
   if (!scorefile)
     lose_syserr ("Couldn't allocate score file");
 
-  strcpy (scorefile, prefix);
-  strcat (scorefile, "/");
-  strcat (scorefile, argv[optind]);
+  char *z = stpcpy (scorefile, prefix);
+  *z++ = '/';
+  strcpy (z, argv[optind]);
 
   newscore.score = normalize_integer (argv[optind + 1]);
   if (! newscore.score)
@@ -430,8 +430,7 @@ write_scores (const char *filename, const struct score_entry *scores,
   char *tempfile = malloc (strlen (filename) + strlen (".tempXXXXXX") + 1);
   if (!tempfile)
     return -1;
-  strcpy (tempfile, filename);
-  strcat (tempfile, ".tempXXXXXX");
+  strcpy (stpcpy (tempfile, filename), ".tempXXXXXX");
   fd = mkostemp (tempfile, 0);
   if (fd < 0)
     return -1;
@@ -462,8 +461,7 @@ lock_file (const char *filename, void **state)
   char *lockpath = malloc (strlen (filename) + strlen (lockext) + 60);
   if (!lockpath)
     return -1;
-  strcpy (lockpath, filename);
-  strcat (lockpath, lockext);
+  strcpy (stpcpy (lockpath, filename), lockext);
   *state = lockpath;
 
   while ((fd = open (lockpath, O_CREAT | O_EXCL, 0600)) < 0)