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.

1 files changed, 12 insertions, 21 deletions

diff --git a/src/doc.c b/src/doc.c
index 1b87c23e949..1d9c330d12c 100644
--- a/src/doc.c
+++ b/src/doc.c
@@ -42,6 +42,8 @@ static ptrdiff_t get_doc_string_buffer_size;
 
 static unsigned char *read_bytecode_pointer;
 
+static char const sibling_etc[] = "../etc/";
+
 /* `readchar' in lread.c calls back here to fetch the next byte.
    If UNREADFLAG is 1, we unread a byte.  */
 
@@ -80,7 +82,6 @@ get_doc_string (Lisp_Object filepos, bool unibyte, bool definition)
 {
   char *from, *to, *name, *p, *p1;
   int fd;
-  ptrdiff_t minsize;
   int offset;
   EMACS_INT position;
   Lisp_Object file, tem, pos;
@@ -113,21 +114,14 @@ get_doc_string (Lisp_Object filepos, bool unibyte, bool definition)
 
   tem = Ffile_name_absolute_p (file);
   file = ENCODE_FILE (file);
-  if (NILP (tem))
-    {
-      Lisp_Object docdir = ENCODE_FILE (Vdoc_directory);
-      minsize = SCHARS (docdir);
-      /* sizeof ("../etc/") == 8 */
-      if (minsize < 8)
-	minsize = 8;
-      name = SAFE_ALLOCA (minsize + SCHARS (file) + 8);
-      char *z = lispstpcpy (name, docdir);
-      strcpy (z, SSDATA (file));
-    }
-  else
-    {
-      name = SSDATA (file);
-    }
+  Lisp_Object docdir
+    = NILP (tem) ? ENCODE_FILE (Vdoc_directory) : empty_unibyte_string;
+  ptrdiff_t docdir_sizemax = SBYTES (docdir) + 1;
+#ifndef CANNOT_DUMP
+  docdir_sizemax = max (docdir_sizemax, sizeof sibling_etc);
+#endif
+  name = SAFE_ALLOCA (docdir_sizemax + SBYTES (file));
+  lispstpcpy (lispstpcpy (name, docdir), file);
 
   fd = emacs_open (name, O_RDONLY, 0);
   if (fd < 0)
@@ -137,8 +131,7 @@ get_doc_string (Lisp_Object filepos, bool unibyte, bool definition)
 	{
 	  /* Preparing to dump; DOC file is probably not installed.
 	     So check in ../etc.  */
-	  strcpy (name, "../etc/");
-	  strcat (name, SSDATA (file));
+	  lispstpcpy (stpcpy (name, sibling_etc), file);
 
 	  fd = emacs_open (name, O_RDONLY, 0);
 	}
@@ -580,7 +573,6 @@ the same file name is found in the `doc-directory'.  */)
       (0)
 #endif /* CANNOT_DUMP */
     {
-      static char const sibling_etc[] = "../etc/";
       dirname = sibling_etc;
       dirlen = sizeof sibling_etc - 1;
     }
@@ -594,8 +586,7 @@ the same file name is found in the `doc-directory'.  */)
   count = SPECPDL_INDEX ();
   USE_SAFE_ALLOCA;
   name = SAFE_ALLOCA (dirlen + SBYTES (filename) + 1);
-  strcpy (name, dirname);
-  strcat (name, SSDATA (filename)); 	/*** Add this line ***/
+  lispstpcpy (stpcpy (name, dirname), filename); 	/*** Add this line ***/
 
   /* Vbuild_files is nil when temacs is run, and non-nil after that.  */
   if (NILP (Vbuild_files))