sonata: add backend startup handshake reader

lib/so_beread.c

@@ -0,0 +1,47 @@
+
+/*
+ * sonata.
+ *
+ * Protocol-level PostgreSQL client library.
+*/
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+#include <assert.h>
+
+#include <so_macro.h>
+#include <so_stream.h>
+#include <so_header.h>
+#include <so_beread.h>
+
+int so_beread_startup(sobestartup_t *su, uint8_t *data, uint32_t size)
+{
+	uint32_t pos_size = size;
+	uint8_t *pos = data;
+	int rc;
+	uint32_t version;
+	rc = so_stream_read32(&version, &pos, &pos_size);
+	if (so_unlikely(rc == -1))
+		return -1;
+	switch (version) {
+	/* StartupMessage */
+	case 196608:
+		su->is_cancel = 0;
+		break;
+	/* CancelRequest */
+	case 80877102: {
+		su->is_cancel = 1;
+		rc = so_stream_read32(&su->key_pid, &pos, &pos_size);
+		if (so_unlikely(rc == -1))
+		rc = so_stream_read32(&su->key, &pos, &pos_size);
+		if (so_unlikely(rc == -1))
+			return -1;
+		break;
+	}
+	default:
+		return -1;
+	}
+	return 0;
+}

lib/so_beread.h

@@ -0,0 +1,20 @@
+#ifndef SO_BEREAD_H_
+#define SO_BEREAD_H_
+
+/*
+ * sonata.
+ *
+ * Protocol-level PostgreSQL client library.
+*/
+
+typedef struct sobestartup_t sobestartup_t;
+
+struct sobestartup_t {
+	int      is_cancel;
+	uint32_t key;
+	uint32_t key_pid;
+};
+
+int so_beread_startup(sobestartup_t*, uint8_t*, uint32_t);
+
+#endif