X-Git-Url: https://git.saurik.com/redis.git/blobdiff_plain/f9c6f39b2b0039cf29df6597d41c124048c825cd..af0b220756571bc8faf57a0c7b7389dd86a60376:/src/rio.c

diff --git a/src/rio.c b/src/rio.c
index e69d939f..45bb8989 100644
--- a/src/rio.c
+++ b/src/rio.c
@@ -1,18 +1,69 @@
+/* rio.c is a simple stream-oriented I/O abstraction that provides an interface
+ * to write code that can consume/produce data using different concrete input
+ * and output devices. For instance the same rdb.c code using the rio
+ * abstraction can be used to read and write the RDB format using in-memory
+ * buffers or files.
+ *
+ * A rio object provides the following methods:
+ *  read: read from stream.
+ *  write: write to stream.
+ *  tell: get the current offset.
+ *
+ * It is also possible to set a 'checksum' method that is used by rio.c in order
+ * to compute a checksum of the data written or read, or to query the rio object
+ * for the current checksum.
+ *
+ * ----------------------------------------------------------------------------
+ *
+ * Copyright (c) 2009-2012, Pieter Noordhuis <pcnoordhuis at gmail dot com>
+ * Copyright (c) 2009-2012, Salvatore Sanfilippo <antirez at gmail dot com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   * Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *   * Neither the name of Redis nor the names of its contributors may be used
+ *     to endorse or promote products derived from this software without
+ *     specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+
+#include "fmacros.h"
 #include <string.h>
+#include <stdio.h>
 #include "rio.h"
 #include "util.h"
 
+uint64_t crc64(uint64_t crc, const unsigned char *s, uint64_t l);
+
 /* Returns 1 or 0 for success/failure. */
 static size_t rioBufferWrite(rio *r, const void *buf, size_t len) {
     r->io.buffer.ptr = sdscatlen(r->io.buffer.ptr,(char*)buf,len);
     r->io.buffer.pos += len;
-    return len;
+    return 1;
 }
 
 /* Returns 1 or 0 for success/failure. */
 static size_t rioBufferRead(rio *r, void *buf, size_t len) {
     if (sdslen(r->io.buffer.ptr)-r->io.buffer.pos < len)
-        return 0;
+        return 0; /* not enough buffer to return len bytes. */
     memcpy(buf,r->io.buffer.ptr+r->io.buffer.pos,len);
     r->io.buffer.pos += len;
     return 1;
@@ -42,6 +93,8 @@ static const rio rioBufferIO = {
     rioBufferRead,
     rioBufferWrite,
     rioBufferTell,
+    NULL,           /* update_checksum */
+    0,              /* current checksum */
     { { NULL, 0 } } /* union for io-specific vars */
 };
 
@@ -49,21 +102,32 @@ static const rio rioFileIO = {
     rioFileRead,
     rioFileWrite,
     rioFileTell,
+    NULL,           /* update_checksum */
+    0,              /* current checksum */
     { { NULL, 0 } } /* union for io-specific vars */
 };
 
-rio rioInitWithFile(FILE *fp) {
-    rio r = rioFileIO;
-    r.io.file.fp = fp;
-    return r;
+void rioInitWithFile(rio *r, FILE *fp) {
+    *r = rioFileIO;
+    r->io.file.fp = fp;
+}
+
+void rioInitWithBuffer(rio *r, sds s) {
+    *r = rioBufferIO;
+    r->io.buffer.ptr = s;
+    r->io.buffer.pos = 0;
 }
-rio rioInitWithBuffer(sds s) {
-    rio r = rioBufferIO;
-    r.io.buffer.ptr = s;
-    r.io.buffer.pos = 0;
-    return r;
+
+/* This function can be installed both in memory and file streams when checksum
+ * computation is needed. */
+void rioGenericUpdateChecksum(rio *r, const void *buf, size_t len) {
+    r->cksum = crc64(r->cksum,buf,len);
 }
 
+/* ------------------------------ Higher level interface ---------------------------
+ * The following higher level functions use lower level rio.c functions to help
+ * generating the Redis protocol for the Append Only File. */
+
 /* Write multi bulk count in the format: "*<count>\r\n". */
 size_t rioWriteBulkCount(rio *r, char prefix, int count) {
     char cbuf[128];