From e332a32b3514d8a5603610e9e9febd5f6ddaae3c Mon Sep 17 00:00:00 2001
From: Pieter Noordhuis <pcnoordhuis@gmail.com>
Date: Mon, 18 Oct 2010 15:49:52 +0200
Subject: [PATCH] Change redisWriteBuffer to return OK on an empty buffer

---
 hiredis.c | 46 ++++++++++++++++++++++++++++------------------
 test.c    | 22 ++++++++++++++++++++++
 2 files changed, 50 insertions(+), 18 deletions(-)

diff --git a/hiredis.c b/hiredis.c
index 45a932a..585dfe8 100644
--- a/hiredis.c
+++ b/hiredis.c
@@ -714,25 +714,35 @@ int redisProcessCallbacks(redisContext *c) {
     return REDIS_OK;
 }
 
-/* Use this function to try and write the entire output buffer to the
- * descriptor. Returns 1 when the entire buffer was written, 0 otherwise. */
+/* Write the output buffer to the socket.
+ *
+ * Returns REDIS_OK when the buffer is empty, or (a part of) the buffer was
+ * succesfully written to the socket. When the buffer is empty after the
+ * write operation, "wdone" is set to 1 (if given).
+ *
+ * Returns REDIS_ERR if an error occured trying to write and sets
+ * c->error to hold the appropriate error string.
+ */
 int redisBufferWrite(redisContext *c, int *done) {
-    int nwritten = write(c->fd,c->obuf,sdslen(c->obuf));
-    if (nwritten == -1) {
-        if (errno == EAGAIN) {
-            /* Try again later */
-        } else {
-            /* Set error in context */
-            c->error = sdscatprintf(sdsempty(),
-                "write: %s", strerror(errno));
-            return REDIS_ERR;
-        }
-    } else if (nwritten > 0) {
-        if (nwritten == (signed)sdslen(c->obuf)) {
-            sdsfree(c->obuf);
-            c->obuf = sdsempty();
-        } else {
-            c->obuf = sdsrange(c->obuf,nwritten,-1);
+    int nwritten;
+    if (sdslen(c->obuf) > 0) {
+        nwritten = write(c->fd,c->obuf,sdslen(c->obuf));
+        if (nwritten == -1) {
+            if (errno == EAGAIN) {
+                /* Try again later */
+            } else {
+                /* Set error in context */
+                c->error = sdscatprintf(sdsempty(),
+                    "write: %s", strerror(errno));
+                return REDIS_ERR;
+            }
+        } else if (nwritten > 0) {
+            if (nwritten == (signed)sdslen(c->obuf)) {
+                sdsfree(c->obuf);
+                c->obuf = sdsempty();
+            } else {
+                c->obuf = sdsrange(c->obuf,nwritten,-1);
+            }
         }
     }
     if (done != NULL) *done = (sdslen(c->obuf) == 0);
diff --git a/test.c b/test.c
index 09bc32d..2800616 100644
--- a/test.c
+++ b/test.c
@@ -4,6 +4,7 @@
 #include <strings.h>
 #include <sys/time.h>
 #include <assert.h>
+#include <unistd.h>
 
 #include "hiredis.h"
 
@@ -203,6 +204,7 @@ static void __test_callback(redisContext *c, const void *privdata) {
 
 static void test_nonblocking_connection() {
     redisContext *c;
+    int wdone = 0;
 
     __test_callback_flags = 0;
     test("Calls command callback when command is issued: ");
@@ -227,6 +229,26 @@ static void test_nonblocking_connection() {
     redisSetFreeCallback(c,__test_callback,(const void*)4);
     redisFree(c);
     test_cond(__test_callback_flags == ((2 << 8) | 4));
+
+    test("redisBufferWrite against empty write buffer: ");
+    c = redisConnectNonBlock("127.0.0.1", 6379, NULL);
+    test_cond(redisBufferWrite(c,&wdone) == REDIS_OK && wdone == 1);
+    redisFree(c);
+
+    test("redisBufferWrite against not yet connected fd: ");
+    c = redisConnectNonBlock("127.0.0.1", 6379, NULL);
+    redisCommand(c,"PING");
+    test_cond(redisBufferWrite(c,NULL) == REDIS_ERR &&
+              strncmp(c->error,"write:",6) == 0);
+    redisFree(c);
+
+    test("redisBufferWrite against closed fd: ");
+    c = redisConnectNonBlock("127.0.0.1", 6379, NULL);
+    redisCommand(c,"PING");
+    redisDisconnect(c);
+    test_cond(redisBufferWrite(c,NULL) == REDIS_ERR &&
+              strncmp(c->error,"write:",6) == 0);
+    redisFree(c);
 }
 
 int main(void) {