tweaks: use a string-copy function that checks for out-of-memory

src/files.c

@@ -2303,7 +2303,7 @@ char *real_dir_from_tilde(const char *path)
 		if (userdata != NULL)
 			tilded = mallocstrcpy(tilded, userdata->pw_dir);
 #else
-		tilded = strdup("");
+		tilded = copy_of("");
 #endif
 	}
 

src/help.c

@@ -103,7 +103,7 @@ void do_help(void)
 #ifdef ENABLE_COLOR
 	char *was_syntax = syntaxstr;
 #endif
-	char *saved_answer = (answer != NULL) ? strdup(answer) : NULL;
+	char *saved_answer = (answer != NULL) ? copy_of(answer) : NULL;
 		/* The current answer when the user invokes help at the prompt. */
 	unsigned stash[sizeof(flags) / sizeof(flags[0])];
 		/* A storage place for the current flag settings. */

src/rcfile.c

@@ -175,7 +175,7 @@ void jot_error(const char *msg, ...)
 	errors_tail = error;
 
 	if (rcfile_with_errors == NULL)
-		rcfile_with_errors = strdup(nanorc);
+		rcfile_with_errors = copy_of(nanorc);
 
 	if (lineno > 0)
 		length = snprintf(textbuf, MAXSIZE, _("Error in %s on line %zu: "),
@@ -326,7 +326,7 @@ void begin_new_syntax(char *ptr)
 	/* Initialize a new syntax struct. */
 	live_syntax = (syntaxtype *)nmalloc(sizeof(syntaxtype));
 	live_syntax->name = copy_of(nameptr);
-	live_syntax->filename = strdup(nanorc);
+	live_syntax->filename = copy_of(nanorc);
 	live_syntax->lineno = lineno;
 	live_syntax->augmentations = NULL;
 	live_syntax->extensions = NULL;
@@ -1050,8 +1050,8 @@ void parse_rcfile(FILE *rcstream, bool just_syntax, bool intros_only)
 				continue;
 			}
 
-			argument = strdup(ptr);
 			keyword = ptr;
+			argument = copy_of(ptr);
 			ptr = parse_next_word(ptr);
 
 			/* File-matching commands need to be processed immediately;
@@ -1064,7 +1064,7 @@ void parse_rcfile(FILE *rcstream, bool just_syntax, bool intros_only)
 			} else {
 				newitem = nmalloc(sizeof(augmentstruct));;
 
-				newitem->filename = strdup(nanorc);
+				newitem->filename = copy_of(nanorc);
 				newitem->lineno = lineno;
 				newitem->data = argument;
 				newitem->next = NULL;