toolchain: add new debugging tool using magenta_debug

toolchain/mxdbg/client/command.c

@@ -0,0 +1,74 @@
+#include "command.h"
+
+#include <stdbool.h>
+#include <stdio.h>
+
+static int command_name_compare(const char *cmd_name, const char *target)
+{
+	int score = 0;
+
+	for (size_t i = 0;; i++) {
+		if (cmd_name[i] != target[i]) {
+			break;
+		}
+
+		if (!cmd_name[i]) {
+			break;
+		}
+
+		score++;
+	}
+
+	return score;
+}
+
+const struct command *command_find(
+	const struct command **commands,
+	size_t nr_commands,
+	const char *name)
+{
+	int best_score = 0;
+	const struct command *best_match = NULL;
+	bool ambiguous = false;
+
+	for (size_t i = 0; i < nr_commands; i++) {
+		int score = command_name_compare(commands[i]->cmd_name, name);
+		if (score == best_score && score > 0) {
+			ambiguous = true;
+		}
+
+		if (score > best_score) {
+			ambiguous = false;
+			best_score = score;
+			best_match = commands[i];
+		}
+	}
+
+	if (!best_match) {
+		printf("'%s' is not a valid command.\n", name);
+		return NULL;
+	}
+
+	if (!ambiguous) {
+		return best_match;
+	}
+
+	printf("command name '%s' is ambiguous, and could refer to multiple "
+	       "commands.\n",
+	       name);
+	return NULL;
+}
+
+int command_execute(
+	const struct command *cmd,
+	struct debug_context *ctx,
+	int argc,
+	const char **argv,
+	void *argp)
+{
+	if (!cmd->cmd_callback) {
+		return -1;
+	}
+
+	return cmd->cmd_callback(cmd, ctx, argc, argv, argp);
+}