Add tac. (Shell wrapper is smaller, but all-in-one static binary is compelling use case.)

toys/tac.c

@@ -0,0 +1,55 @@
+/* vi: set sw=4 ts=4:
+ *
+ * tac.c - output lines in reverse order
+ *
+ * Copyright 2012 Rob Landley <rob@landley.net>
+ *
+ * Not in SUSv4.
+
+USE_TAC(NEWTOY(tac, NULL, TOYFLAG_USR|TOYFLAG_BIN))
+
+config TAC
+	bool "tac"
+	default y
+	help
+	  usage: tac [FILE...]
+
+	  Output lines in reverse order.
+*/
+
+#include "toys.h"
+
+void do_tac(int fd, char *name)
+{
+	struct arg_list *list = NULL;
+	char *c;
+
+	// Read in lines
+	for (;;) {
+		struct arg_list *temp;
+		int len;
+
+		if (!(c = get_line(fd))) break;
+
+		len = strlen(c);
+		if (len && c[len-1]=='\n') c[len-1] = 0;
+		temp = xmalloc(sizeof(struct arg_list));
+		temp->next = list;
+		temp->arg = c;
+		list = temp;
+	}
+
+	// Play them back.
+	while (list) {
+		struct arg_list *temp = list->next;
+		xputs(list->arg);
+		free(list->arg);
+		free(list);
+		list = temp;
+	}
+}
+
+void tac_main(void)
+{
+	loopfiles(toys.optargs, do_tac);
+}