Change error reporting to have an explicit type

When there is an I/O error, errno should be used to find out what is
wrong. In other cases, errno cannot be used. So, use an explicit type in
Hiredis to define the different error scenarios that can occur.

6 files changed, 47 insertions, 28 deletions

diff --git a/async.c b/async.c
index d6a33f9..424c2b2 100644
--- a/async.c
+++ b/async.c
@@ -47,8 +47,8 @@ static redisAsyncContext *redisAsyncInitialize(redisContext *c) {
  * an indirection to the redisContext struct. */
 static void __redisAsyncCopyError(redisAsyncContext *ac) {
     redisContext *c = &(ac->c);
-    if (c->error != NULL)
-        ac->error = c->error;
+    ac->err = c->err;
+    ac->errstr = c->errstr;
 }
 
 redisAsyncContext *redisAsyncConnect(const char *ip, int port) {
@@ -128,7 +128,7 @@ static void __redisAsyncDisconnect(redisAsyncContext *ac) {
 
     /* Make sure error is accessible if there is any */
     __redisAsyncCopyError(ac);
-    status = (ac->error == NULL) ? REDIS_OK : REDIS_ERR;
+    status = (ac->err == 0) ? REDIS_OK : REDIS_ERR;
 
     if (status == REDIS_OK) {
         /* When the connection is cleanly disconnected, there should not
diff --git a/async.h b/async.h
index 2e14b13..d0a99da 100644
--- a/async.h
+++ b/async.h
@@ -54,8 +54,9 @@ typedef struct redisAsyncContext {
     /* Hold the regular context, so it can be realloc'ed. */
     redisContext c;
 
-    /* Hold a reference to the error object so it can be used directly. */
-    char *error;
+    /* Setup error flags so they can be used directly. */
+    int err;
+    char *errstr;
 
     /* Called when the library expects to start reading/writing.
      * The supplied functions should be idempotent. */
diff --git a/example.c b/example.c
index d784e33..676814a 100644
--- a/example.c
+++ b/example.c
@@ -10,8 +10,8 @@ int main(void) {
     redisReply *reply;
 
     c = redisConnect((char*)"127.0.0.1", 6379);
-    if (c->error != NULL) {
-        printf("Connection error: %s\n", c->error);
+    if (c->err) {
+        printf("Connection error: %s\n", c->errstr);
         exit(1);
     }
 
diff --git a/hiredis.c b/hiredis.c
index 8848def..0aabd25 100644
--- a/hiredis.c
+++ b/hiredis.c
@@ -614,6 +614,17 @@ int redisFormatCommandArgv(char **target, int argc, const char **argv, const siz
     return totlen;
 }
 
+static void __redisSetError(redisContext *c, int type, const char *str) {
+    c->err = type;
+    if (str) {
+        c->errstr = sdsnew(str);
+    } else {
+        /* Only REDIS_ERR_IO may lack a description! */
+        assert(type == REDIS_ERR_IO);
+        c->errstr = sdsnew(strerror(errno));
+    }
+}
+
 static int redisContextConnect(redisContext *c, const char *ip, int port) {
     char err[ANET_ERR_LEN];
     if (c->flags & REDIS_BLOCK) {
@@ -623,11 +634,11 @@ static int redisContextConnect(redisContext *c, const char *ip, int port) {
     }
 
     if (c->fd == ANET_ERR) {
-        c->error = sdsnew(err);
+        __redisSetError(c,REDIS_ERR_CONN,err);
         return REDIS_ERR;
     }
     if (anetTcpNoDelay(err,c->fd) == ANET_ERR) {
-        c->error = sdsnew(err);
+        __redisSetError(c,REDIS_ERR_CONN,err);
         return REDIS_ERR;
     }
     return REDIS_OK;
@@ -635,7 +646,8 @@ static int redisContextConnect(redisContext *c, const char *ip, int port) {
 
 static redisContext *redisContextInit() {
     redisContext *c = calloc(sizeof(redisContext),1);
-    c->error = NULL;
+    c->err = 0;
+    c->errstr = NULL;
     c->obuf = sdsempty();
     c->fn = &defaultFunctions;
     c->reader = NULL;
@@ -646,8 +658,8 @@ void redisFree(redisContext *c) {
     /* Disconnect before free'ing if not yet disconnected. */
     if (c->flags & REDIS_CONNECTED)
         close(c->fd);
-    if (c->error != NULL)
-        sdsfree(c->error);
+    if (c->errstr != NULL)
+        sdsfree(c->errstr);
     if (c->obuf != NULL)
         sdsfree(c->obuf);
     if (c->reader != NULL)
@@ -702,14 +714,12 @@ int redisBufferRead(redisContext *c) {
         if (errno == EAGAIN) {
             /* Try again later */
         } else {
-            /* Set error in context */
-            c->error = sdscatprintf(sdsempty(),
-                "read: %s", strerror(errno));
+            __redisSetError(c,REDIS_ERR_IO,NULL);
             return REDIS_ERR;
         }
     } else if (nread == 0) {
-        c->error = sdscatprintf(sdsempty(),
-            "read: Server closed the connection");
+        __redisSetError(c,REDIS_ERR_EOF,
+            "Server closed the connection");
         return REDIS_ERR;
     } else {
         __redisCreateReplyReader(c);
@@ -735,9 +745,7 @@ int redisBufferWrite(redisContext *c, int *done) {
             if (errno == EAGAIN) {
                 /* Try again later */
             } else {
-                /* Set error in context */
-                c->error = sdscatprintf(sdsempty(),
-                    "write: %s", strerror(errno));
+                __redisSetError(c,REDIS_ERR_IO,NULL);
                 return REDIS_ERR;
             }
         } else if (nwritten > 0) {
@@ -758,8 +766,7 @@ int redisBufferWrite(redisContext *c, int *done) {
 static int __redisGetReply(redisContext *c, void **reply) {
     __redisCreateReplyReader(c);
     if (redisReplyReaderGetReply(c->reader,reply) == REDIS_ERR) {
-        /* Copy the (protocol) error from the reader to the context. */
-        c->error = sdsnew(((redisReader*)c->reader)->error);
+        __redisSetError(c,REDIS_ERR_PROTOCOL,((redisReader*)c->reader)->error);
         return REDIS_ERR;
     }
     return REDIS_OK;
diff --git a/hiredis.h b/hiredis.h
index a68720e..76d7264 100644
--- a/hiredis.h
+++ b/hiredis.h
@@ -35,6 +35,15 @@
 #define REDIS_ERR -1
 #define REDIS_OK 0
 
+/* When an error occurs, the err flag in a context is set to hold the type of
+ * error that occured. REDIS_ERR_IO means there was an I/O error and you
+ * should use the "errno" variable to find out what is wrong.
+ * For other values, the "errstr" field will hold a description. */
+#define REDIS_ERR_IO 1 /* error in read or write */
+#define REDIS_ERR_CONN 2 /* error connecting */
+#define REDIS_ERR_EOF 3 /* eof */
+#define REDIS_ERR_PROTOCOL 4 /* protocol error */
+
 /* Connection type can be blocking or non-blocking and is set in the
  * least significant bit of the flags field in redisContext. */
 #define REDIS_BLOCK 0x1
@@ -87,8 +96,9 @@ struct redisContext; /* need forward declaration of redisContext */
 typedef struct redisContext {
     int fd;
     int flags;
-    char *error; /* Error object is set when in erronous state */
     char *obuf; /* Write buffer */
+    int err; /* Error flags, 0 when there is no error */
+    char *errstr; /* String representation of error when applicable */
 
     /* Function set for reply buildup and reply reader */
     redisReplyObjectFunctions *fn;
diff --git a/test.c b/test.c
index b6e86f5..11e762b 100644
--- a/test.c
+++ b/test.c
@@ -22,8 +22,8 @@ static long long usec(void) {
 static redisContext *blocking_context = NULL;
 static void __connect(redisContext **target) {
     *target = blocking_context = redisConnect((char*)"127.0.0.1", 6379);
-    if (blocking_context->error != NULL) {
-        printf("Connection error: %s\n", blocking_context->error);
+    if (blocking_context->err) {
+        printf("Connection error: %s\n", blocking_context->errstr);
         exit(1);
     }
 }
@@ -77,9 +77,10 @@ static void test_blocking_connection() {
     __connect(&c);
     test("Returns I/O error when the connection is lost: ");
     reply = redisCommand(c,"QUIT");
-    test_cond(redisCommand(c,"PING") == NULL &&
-        strcasecmp(reply->str,"OK") == 0 &&
-        strcmp(c->error,"read: Server closed the connection") == 0);
+    test_cond(strcasecmp(reply->str,"OK") == 0 &&
+        redisCommand(c,"PING") == NULL &&
+        c->err == REDIS_ERR_EOF &&
+        strcmp(c->errstr,"Server closed the connection") == 0);
     freeReplyObject(reply);
     redisFree(c);