sed: support GNU-like '\t' escape in substitutions

editors/sed.c

@@ -173,7 +173,7 @@ static void cleanup_outname(void)
 	if (G.outname) unlink(G.outname);
 }
 
-/* strdup, replacing "\n" with '\n', and "\delimiter" with 'delimiter' */
+/* strcpy, replacing "\from" with 'to'. If to is NUL, replacing "\any" with 'any' */
 
 static void parse_escapes(char *dest, const char *string, int len, char from, char to)
 {
@@ -188,9 +188,10 @@ static void parse_escapes(char *dest, const char *string, int len, char from, ch
 			}
 			*dest++ = string[i++];
 		}
+		/* TODO: is it safe wrt a string with trailing '\\' ? */
 		*dest++ = string[i++];
 	}
-	*dest = 0;
+	*dest = '\0';
 }
 
 static char *copy_parsing_escapes(const char *string, int len)
@@ -198,6 +199,8 @@ static char *copy_parsing_escapes(const char *string, int len)
 	char *dest = xmalloc(len + 1);
 
 	parse_escapes(dest, string, len, 'n', '\n');
+	/* GNU sed also recognizes \t */
+	parse_escapes(dest, dest, strlen(dest), 't', '\t');
 	return dest;
 }
 
@@ -205,7 +208,7 @@ static char *copy_parsing_escapes(const char *string, int len)
 /*
  * index_of_next_unescaped_regexp_delim - walks left to right through a string
  * beginning at a specified index and returns the index of the next regular
- * expression delimiter (typically a forward * slash ('/')) not preceded by
+ * expression delimiter (typically a forward slash ('/')) not preceded by
  * a backslash ('\').  A negative delimiter disables square bracket checking.
  */
 static int index_of_next_unescaped_regexp_delim(int delimiter, const char *str)
@@ -425,7 +428,8 @@ static const char *parse_cmd_args(sed_cmd_t *sed_cmd, const char *cmdstr)
 				break;
 		}
 		sed_cmd->string = xstrdup(cmdstr);
-		parse_escapes(sed_cmd->string, sed_cmd->string, strlen(cmdstr), 0, 0);
+		/* "\anychar" -> "anychar" */
+		parse_escapes(sed_cmd->string, sed_cmd->string, strlen(cmdstr), '\0', '\0');
 		cmdstr += strlen(cmdstr);
 	/* handle file cmds: (r)ead */
 	} else if (strchr("rw", sed_cmd->cmd)) {
@@ -1337,7 +1341,7 @@ int sed_main(int argc, char **argv)
 			// FIXME: error check / message?
 			rename(G.outname, argv[i]);
 			free(G.outname);
-			G.outname = 0;
+			G.outname = NULL;
 		}
 		if (G.input_file_count > G.current_input_file)
 			process_files();

testsuite/README

@@ -4,7 +4,9 @@ Update: doesn't work as described. Try "make check" from parent dir...
 To run the test suite, change to this directory and run "./runtest".  It will
 run all of the test cases, and list those with unexpected outcomes.  Adding the
 -v option will cause it to show expected outcomes as well.  To only run the test
-cases for particular applets, specify them as parameters to runtest.
+cases for particular applets:
+
+./runtest <applet1> <applet2>...
 
 The test cases for an applet reside in the subdirectory of the applet name.  The
 name of the test case should be the assertion that is tested.  The test case

testsuite/sed.tests

@@ -57,6 +57,7 @@ testing "sed s arbitrary delimiter" "sed -e 's woo boing '" "boing\n" "" "woo\n"
 testing "sed s chains" "sed -e s/foo/bar/ -e s/bar/baz/" "baz\n" "" "foo\n"
 testing "sed s chains2" "sed -e s/foo/bar/ -e s/baz/nee/" "bar\n" "" "foo\n"
 testing "sed s [delimiter]" "sed -e 's@[@]@@'" "onetwo" "" "one@two"
+testing "sed s with \\t (GNU ext)" "sed 's/\t/ /'" "one two" "" "one\ttwo"
 
 # branch
 testing "sed b (branch)" "sed -e 'b one;p;: one'" "foo\n" "" "foo\n"