Add initCallback and deinitCallback for openWithReadCallback

1 files changed, 6 insertions, 2 deletions

diff --git a/src/cc4group.h b/src/cc4group.h
index cc04a4f..76a0970 100644
--- a/src/cc4group.h
+++ b/src/cc4group.h
@@ -37,6 +37,10 @@ typedef void* (*CC4Group_TmpMemoryStrategy)(CC4Group* const this, const size_t s
 // the pointer passed in will be handled as specified with the corresponding MemoryManagement
 typedef bool (*CC4Group_ReadCallback)(const void** const data, size_t* const size, void* const arg);
 
+// can be used as initialization before and deinitialization after all necessary calls to a read callback are made; for instance for buffer allocation and deletion
+// the callback should return true on success and false on failure
+typedef bool (*CC4Group_ReadSetupCallback)(void* const arg);
+
 typedef struct {
 	CC4Group* (*new)(void);
 	bool (*create)(CC4Group* const this);
@@ -60,8 +64,8 @@ typedef struct {
 	// the file must have been opened with read access; also be aware that the file must be opened with binary mode on windows
 	bool (*openFilePointer)(CC4Group* const this, FILE* fd);
 
-	// opens a group and calls the callback to get the group data
-	bool (*openWithReadCallback)(CC4Group* const this, CC4Group_ReadCallback const callback, void* const callbackArg, int const memoryManagement);
+	// opens a group and calls the callback to get the group data; initCallback is called before readCallback is called and deinitCallback is called after all read operations are done; initCallback and deinitCallback may be NULL if they should not be used
+	bool (*openWithReadCallback)(CC4Group* const this, CC4Group_ReadCallback const readCallback, void* const callbackArg, int const memoryManagement, CC4Group_ReadSetupCallback const initCallback, CC4Group_ReadSetupCallback const deinitCallback);
 
 	bool (*save)(CC4Group* const this, const char* const path);
 	bool (*saveOverwrite)(CC4Group* const this, const char* const path);