Abstract file/buffer I/O to support in-memory serialization

src/rio.h

@@ -0,0 +1,39 @@
+#ifndef __REDIS_RIO_H
+#define __REDIS_RIO_H
+
+#include <stdio.h>
+#include "sds.h"
+
+struct _rio {
+    /* Backend functions. Both read and write should return 0 for short reads
+     * or writes, identical to the return values of fread/fwrite. */
+    size_t (*read)(struct _rio *, void *buf, size_t len);
+    size_t (*write)(struct _rio *, const void *buf, size_t len);
+    off_t (*tell)(struct _rio *);
+
+    /* Backend-specific vars. */
+    union {
+        struct {
+            sds ptr;
+            off_t pos;
+        } buffer;
+        struct {
+            FILE *fp;
+        } file;
+    } io;
+};
+
+typedef struct _rio rio;
+
+#define rioWrite(rio,buf,len) ((rio)->write((rio),(buf),(len)))
+#define rioRead(rio,buf,len) ((rio)->read((rio),(buf),(len)))
+
+rio rioInitWithFile(FILE *fp);
+rio rioInitWithBuffer(sds s);
+
+size_t rioWriteBulkCount(rio *r, char prefix, int count);
+size_t rioWriteBulkString(rio *r, const char *buf, size_t len);
+size_t rioWriteBulkLongLong(rio *r, long long l);
+size_t rioWriteBulkDouble(rio *r, double d);
+
+#endif