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+// SPDX-License-Identifier: GPL-2.0-or-later
+
+/* PASST - Plug A Simple Socket Transport
+ *  for qemu/UNIX domain socket mode
+ *
+ * PASTA - Pack A Subtle Tap Abstraction
+ *  for network namespace/tap device mode
+ *
+ * parse.c - Composable parsing helpers
+ *
+ * Copyright Red Hat
+ * Author: David Gibson <david@gibson.dropbear.id.au>
+ */
+
+#include <assert.h>
+#include <stddef.h>
+#include <fcntl.h>
+#include <string.h>
+#include <stdbool.h>
+#include <unistd.h>
+
+#include "common.h"
+
+/**
+ * DOC: Theory of Operation
+ *
+ * These are a number of primitives which can be combined into parsers for
+ * moderately complex input.  For simpler composability, they have common
+ * conventions.
+ *
+ * - Functions return a bool indicating whether they successfully parsed.
+ * - Any specific output from the parse is as output parameters
+ * - First argument is always @cursor, a const char **.
+ * - On entry, *@cursor has the point to start parsing.
+ * - On successful exit, *@cursor is updated to the next character after the
+ *    parsed portion of the input
+ * - On failure, *@cursor and any output arguments are not modified
+ *
+ * For brevity the common parameters and return information are omitted from the
+ * individual function documentation comments.
+ */
+
+/**
+ * parse_literal() - Parse a specified literal string
+ * @cursor:	Point to parse from, updated on success
+ * @lit:	Keyword to accept
+ */
+bool parse_literal(const char **cursor, const char *lit)
+{
+	size_t len = strlen(lit);
+
+	if (strlen(*cursor) < len || memcmp(*cursor, lit, len))
+		return false;
+
+	*cursor += len;
+	return true;
+}
+
+/**
+ * parse_eoi() - Parse end of input
+ * @cursor:	Point to parse from
+ *
+ * Return: true if @p is at End of Input (\0), false otherwise
+ */
+bool parse_eoi(const char *cursor)
+{
+	return !(*cursor);
+}