Change blackboard write/readString prototype

Those functions are used in one place and let the caller transform a
std::string to a char * which makes the use of alloca necessary.
Moreover, the readString cannot know if the pointer given in input
points to a buffer with enough space, making it dangerous.

This patch reworks the API so that write/readString() get std::string
and lets the implementation play with char *. This also allows to get
rid of alloca() use which is quite dangerous.

Change-Id: I973e4987278289bb914c4e194b86e924a1c88a6d
Signed-off-by: Sebastien Gonzalve <sebastien.gonzalve@intel.com>

3 files changed, 9 insertions, 16 deletions

diff --git a/parameter/ParameterBlackboard.cpp b/parameter/ParameterBlackboard.cpp
index 3af9a1d..6001c77 100644
--- a/parameter/ParameterBlackboard.cpp
+++ b/parameter/ParameterBlackboard.cpp
@@ -99,14 +99,14 @@ void CParameterBlackboard::readInteger(void* pvDstData, uint32_t uiSize, uint32_
     }
 }
 
-void CParameterBlackboard::writeString(const char* pcSrcData, uint32_t uiOffset)
+void CParameterBlackboard::writeString(const std::string &input, uint32_t uiOffset)
 {
-    strcpy((char*)_pucData + uiOffset, pcSrcData);
+    strcpy((char*)_pucData + uiOffset, input.c_str());
 }
 
-void CParameterBlackboard::readString(char* pcDstData, uint32_t uiOffset) const
+void CParameterBlackboard::readString(std::string &output, uint32_t uiOffset) const
 {
-    strcpy(pcDstData, (const char*)_pucData + uiOffset);
+    output = std::string((const char*)_pucData + uiOffset);
 }
 
 // Access from/to subsystems
diff --git a/parameter/ParameterBlackboard.h b/parameter/ParameterBlackboard.h
index 111208a..bd48cc4 100644
--- a/parameter/ParameterBlackboard.h
+++ b/parameter/ParameterBlackboard.h
@@ -31,6 +31,7 @@
 
 #include <stdint.h>
 #include "BinaryStream.h"
+#include <string>
 
 class CParameterBlackboard
 {
@@ -45,8 +46,8 @@ public:
     // Single parameter access
     void writeInteger(const void* pvSrcData, uint32_t uiSize, uint32_t uiOffset, bool bBigEndian);
     void readInteger(void* pvDstData, uint32_t uiSize, uint32_t uiOffset, bool bBigEndian) const;
-    void writeString(const char* pcSrcData, uint32_t uiOffset);
-    void readString(char* pcDstData, uint32_t uiOffset) const;
+    void writeString(const std::string &input, uint32_t uiOffset);
+    void readString(std::string &output, uint32_t uiOffset) const;
 
     // Access from/to subsystems
     uint8_t* getLocation(uint32_t uiOffset);
diff --git a/parameter/StringParameter.cpp b/parameter/StringParameter.cpp
index cb13e9b..8ba5b16 100644
--- a/parameter/StringParameter.cpp
+++ b/parameter/StringParameter.cpp
@@ -32,7 +32,6 @@
 #include "ParameterAccessContext.h"
 #include "ConfigurationAccessContext.h"
 #include "ParameterBlackboard.h"
-#include <alloca.h>
 
 #define base CBaseParameter
 
@@ -79,19 +78,12 @@ bool CStringParameter::doSetValue(const string& strValue, uint32_t uiOffset, CPa
     // Write blackboard
     CParameterBlackboard* pBlackboard = parameterAccessContext.getParameterBlackboard();
 
-    pBlackboard->writeString(strValue.c_str(), uiOffset);
+    pBlackboard->writeString(strValue, uiOffset);
 
     return true;
 }
 
 void CStringParameter::doGetValue(string& strValue, uint32_t uiOffset, CParameterAccessContext& parameterAccessContext) const
 {
-    char* pcValue = (char*)alloca(getSize());
-
-    // Read blackboard
-    const CParameterBlackboard* pBlackboard = parameterAccessContext.getParameterBlackboard();
-
-    pBlackboard->readString(pcValue, uiOffset);
-
-    strValue = pcValue;
+    parameterAccessContext.getParameterBlackboard()->readString(strValue, uiOffset);
 }