Add text mode to yrmcds struct.

New error codes:

* YRMCDS_IN_BINARY

    The connection has sent a binary command; therefore
    putting it into text mode is impossible.

* YRMCDS_BAD_KEY

    Key contains white spaces or control characters.

connect.c

@@ -1,4 +1,4 @@
-// (C) 2013 Cybozu.
+// (C) 2013, 2016 Cybozu.
 
 #include "yrmcds.h"
 
@@ -160,6 +160,8 @@ yrmcds_error yrmcds_connect(yrmcds* c, const char* node, uint16_t port) {
     c->last_size = 0;
     c->decompressed = NULL;
     c->invalid = 0;
+    c->text_mode = 0;
+    c->rserial = 0;
     return YRMCDS_OK;
 }
 

strerror.c

@@ -24,6 +24,10 @@ const char* yrmcds_strerror(yrmcds_error e) {
         return "Received malformed packet";
     case YRMCDS_NOT_IMPLEMENTED:
         return "Not implemented";
+    case YRMCDS_IN_BINARY:
+        return "Connection is fixed for binary protocol";
+    case YRMCDS_BAD_KEY:
+        return "Bad key";
     default:
         return "Unknown error";
     };

text_mode.c

@@ -0,0 +1,32 @@
+// (C) 2016 Cybozu.
+
+#include "yrmcds.h"
+
+#include <errno.h>
+
+yrmcds_error yrmcds_text_mode(yrmcds* c) {
+    if( c == NULL )
+        return YRMCDS_BAD_ARGUMENT;
+
+#ifndef LIBYRMCDS_NO_INTERNAL_LOCK
+    int e = pthread_mutex_lock(&c->lock);
+    if( e != 0 ) {
+        errno = e;
+        return YRMCDS_SYSTEM_ERROR;
+    }
+#endif // ! LIBYRMCDS_NO_INTERNAL_LOCK
+
+    yrmcds_error ret = YRMCDS_OK;
+    if( c->serial != 0 ) {
+        ret = YRMCDS_IN_BINARY;
+        goto OUT;
+    }
+
+    c->text_mode = 1;
+
+  OUT:
+#ifndef LIBYRMCDS_NO_INTERNAL_LOCK
+    pthread_mutex_unlock(&c->lock);
+#endif
+    return ret;
+}

yrmcds.h

@@ -1,6 +1,6 @@
 /** @file yrmcds.h
  * libyrmcds public API.
- * (C) 2013-2015 Cybozu.
+ * (C) 2013-2016 Cybozu.
  */
 
 #pragma once
@@ -37,6 +37,10 @@ typedef struct {
     size_t last_size;       ///< size of the last response.
     char*  decompressed;    ///< decompressed data.
     int    invalid;         ///< invalid flag.
+
+    /* for text mode */
+    int      text_mode;     ///< text mode flag.
+    uint32_t rserial;       ///< serial emulation.
 } yrmcds;
 
 
@@ -146,6 +150,8 @@ typedef enum {
     YRMCDS_COMPRESS_FAILED,   ///< LZ4 compression failed.
     YRMCDS_PROTOCOL_ERROR,    ///< received malformed packet.
     YRMCDS_NOT_IMPLEMENTED,   ///< the function is not available.
+    YRMCDS_IN_BINARY,         ///< connection is fixed for binary protocol.
+    YRMCDS_BAD_KEY,           ///< bad key.
 } yrmcds_error;
 
 
@@ -208,6 +214,21 @@ yrmcds_error yrmcds_close(yrmcds* c);
 yrmcds_error yrmcds_shutdown(yrmcds* c);
 
 
+/**
+ * Turn on text protocol mode.
+ * @param  c  A pointer to ::yrmcds.
+ * @return 0 if succeeded.  Other values indicate an error.
+ *
+ * This function puts the connection into text protocol mode.
+ * \p c should be a newly connected object; if any (binary) request
+ * has been sent, this function will return an error.
+ *
+ * Text protocol mode has overheads and limitations; most notably,
+ * \p quiet option for command sending functions cannot be enabled.
+ */
+yrmcds_error yrmcds_text_mode(yrmcds* c);
+
+
 /**
  * Enable/disable (de)compression for large objects.
  * @param  c     A pointer to ::yrmcds.