[cppcheck] Improvements in SaveStorageValue() in core.c (#1160)

* [cppcheck] Improvements in SaveStorageValue() in core.c

in file core.c cppcheck shows errors only in function SaveStorageValue():

* Common realloc mistake: 'fileData' nulled but not freed upon failure
* Memory pointed to by 'fileData' is freed twice.

Validation:
* Tested examples/core/core_storage_values.c
* Launched Unit Test for this function
* Rerun CPPCHECK afer fix

* [cppcheck] Change functions header to accept only positive position in files

Changes:
* Functions SaveStorageValue(), LoadStorageValue() (core.c)
* Functions LoadFileData(), SaveFileData() (utils.c)
* Headers in raylib.h

Validation:
* Tested examples/core/core_storage_values.c
* Launched Unit Test for these functions
* Rerun CPPCHECK afer fix

3 files changed, 42 insertions, 20 deletions

diff --git a/src/core.c b/src/core.c
index 40f20030..11106eac 100644
--- a/src/core.c
+++ b/src/core.c
@@ -16,7 +16,7 @@
 *
 *   #define PLATFORM_DESKTOP
 *       Windowing and input system configured for desktop platforms: Windows, Linux, OSX, FreeBSD, OpenBSD, NetBSD, DragonFly
-*       NOTE: Oculus Rift CV1 requires PLATFORM_DESKTOP for mirror rendering - View [rlgl] module to enable it
+*       NOTE: Oculus Ritf CV1 requires PLATFORM_DESKTOP for mirror rendering - View [rlgl] module to enable it
 *
 *   #define PLATFORM_ANDROID
 *       Windowing and input system configured for Android device, app activity managed internally in this module.
@@ -2192,7 +2192,7 @@ unsigned char *DecompressData(unsigned char *compData, int compDataLength, int *
 
 // Save integer value to storage file (to defined position)
 // NOTE: Storage positions is directly related to file memory layout (4 bytes each integer)
-void SaveStorageValue(int position, int value)
+void SaveStorageValue(unsigned int position, int value)
 {
 #if defined(SUPPORT_DATA_STORAGE)
     char path[512] = { 0 };
@@ -2204,31 +2204,53 @@ void SaveStorageValue(int position, int value)
     strcpy(path, STORAGE_DATA_FILE);
 #endif
 
-    int dataSize = 0;
+    unsigned int dataSize = 0;
+    unsigned int newDataSize = 0;
     unsigned char *fileData = LoadFileData(path, &dataSize);
+    unsigned char *newFileData = NULL;
 
     if (fileData != NULL)
     {
         if (dataSize <= (position*sizeof(int)))
         {
             // Increase data size up to position and store value
-            dataSize = (position + 1)*sizeof(int);
-            fileData = (unsigned char *)RL_REALLOC(fileData, dataSize);
-            int *dataPtr = (int *)fileData;
-            dataPtr[position] = value;
+            newDataSize = (position + 1)*sizeof(int);
+            newFileData = (unsigned char *)RL_REALLOC(fileData, newDataSize);
+
+            if (newFileData != NULL)
+            {
+                // RL_REALLOC succeded
+                int *dataPtr = (int *)newFileData;
+                dataPtr[position] = value;  
+            }
+            else
+            {
+                // RL_REALLOC failed
+                TRACELOG(LOG_WARNING, "FILEIO: Position in bytes (%u) bigger than actual size of file [%s] (%u) Realloc function FAIL",position*sizeof(int),path,dataSize);  
+                
+                // We store the old size of the file.
+                newFileData=fileData;
+                newDataSize=dataSize;
+            }
+            
         }
         else
         {
+            // We store the old size of the file.
+            newFileData=fileData;
+            newDataSize=dataSize;
+
             // Replace value on selected position
-            int *dataPtr = (int *)fileData;
+            int *dataPtr = (int *)newFileData;
             dataPtr[position] = value;
         }
 
-        SaveFileData(path, fileData, dataSize);
-        RL_FREE(fileData);
+        SaveFileData(path, newFileData, newDataSize);
+        RL_FREE(newFileData);
     }
     else
     {
+        TRACELOG(LOG_INFO, "FILEIO: [%s] File not found, creating it.",path);  
         dataSize = (position + 1)*sizeof(int);
         fileData = (unsigned char *)RL_MALLOC(dataSize);
         int *dataPtr = (int *)fileData;
@@ -2242,7 +2264,7 @@ void SaveStorageValue(int position, int value)
 
 // Load integer value from storage file (from defined position)
 // NOTE: If requested position could not be found, value 0 is returned
-int LoadStorageValue(int position)
+int LoadStorageValue(unsigned int position)
 {
     int value = 0;
 #if defined(SUPPORT_DATA_STORAGE)
@@ -2255,7 +2277,7 @@ int LoadStorageValue(int position)
     strcpy(path, STORAGE_DATA_FILE);
 #endif
 
-    int dataSize = 0;
+    unsigned int dataSize = 0;
     unsigned char *fileData = LoadFileData(path, &dataSize);
 
     if (fileData != NULL)
diff --git a/src/raylib.h b/src/raylib.h
index 329a3b71..7005d5a2 100644
--- a/src/raylib.h
+++ b/src/raylib.h
@@ -951,8 +951,8 @@ RLAPI void TakeScreenshot(const char *fileName);                  // Takes a scr
 RLAPI int GetRandomValue(int min, int max);                       // Returns a random value between min and max (both included)
 
 // Files management functions
-RLAPI unsigned char *LoadFileData(const char *fileName, int *bytesRead);     // Load file data as byte array (read)
-RLAPI void SaveFileData(const char *fileName, void *data, int bytesToWrite); // Save data to file from byte array (write)
+RLAPI unsigned char *LoadFileData(const char *fileName, unsigned int *bytesRead);     // Load file data as byte array (read)
+RLAPI void SaveFileData(const char *fileName, void *data, unsigned int bytesToWrite); // Save data to file from byte array (write)
 RLAPI char *LoadFileText(const char *fileName);                   // Load text data from file (read), returns a '\0' terminated string
 RLAPI void SaveFileText(const char *fileName, char *text);        // Save text data to file (write), string must be '\0' terminated
 RLAPI bool FileExists(const char *fileName);                      // Check if file exists
@@ -976,8 +976,8 @@ RLAPI unsigned char *CompressData(unsigned char *data, int dataLength, int *comp
 RLAPI unsigned char *DecompressData(unsigned char *compData, int compDataLength, int *dataLength);  // Decompress data (DEFLATE algorythm)
 
 // Persistent storage management
-RLAPI void SaveStorageValue(int position, int value);             // Save integer value to storage file (to defined position)
-RLAPI int LoadStorageValue(int position);                         // Load integer value from storage file (from defined position)
+RLAPI void SaveStorageValue(unsigned int position, int value);    // Save integer value to storage file (to defined position)
+RLAPI int LoadStorageValue(unsigned int position);                // Load integer value from storage file (from defined position)
 
 RLAPI void OpenURL(const char *url);                              // Open URL with default system browser (if available)
 
diff --git a/src/utils.c b/src/utils.c
index 1fe9e299..5ba8b007 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -165,7 +165,7 @@ void TraceLog(int logType, const char *text, ...)
 }
 
 // Load data from file into a buffer
-unsigned char *LoadFileData(const char *fileName, int *bytesRead)
+unsigned char *LoadFileData(const char *fileName, unsigned int *bytesRead)
 {
     unsigned char *data = NULL;
     *bytesRead = 0;
@@ -187,7 +187,7 @@ unsigned char *LoadFileData(const char *fileName, int *bytesRead)
                 data = (unsigned char *)RL_MALLOC(sizeof(unsigned char)*size);
 
                 // NOTE: fread() returns number of read elements instead of bytes, so we read [1 byte, size elements]
-                int count = fread(data, sizeof(unsigned char), size, file);
+                unsigned int count = fread(data, sizeof(unsigned char), size, file);
                 *bytesRead = count;
 
                 if (count != size) TRACELOG(LOG_WARNING, "FILEIO: [%s] File partially loaded", fileName);
@@ -205,7 +205,7 @@ unsigned char *LoadFileData(const char *fileName, int *bytesRead)
 }
 
 // Save data to file from buffer
-void SaveFileData(const char *fileName, void *data, int bytesToWrite)
+void SaveFileData(const char *fileName, void *data, unsigned int bytesToWrite)
 {
     if (fileName != NULL)
     {
@@ -213,7 +213,7 @@ void SaveFileData(const char *fileName, void *data, int bytesToWrite)
 
         if (file != NULL)
         {
-            int count = fwrite(data, sizeof(unsigned char), bytesToWrite, file);
+            unsigned int count = fwrite(data, sizeof(unsigned char), bytesToWrite, file);
 
             if (count == 0) TRACELOG(LOG_WARNING, "FILEIO: [%s] Failed to write file", fileName);
             else if (count != bytesToWrite) TRACELOG(LOG_WARNING, "FILEIO: [%s] File partially written", fileName);