session_file.h

/**
 * @file   session_file.h
 * @Author Bogdan Dumitru (dumbogdan@gmail.com)
 * @date   July, 2012
 * @brief  Functions related to the processing of Ableton Live Session files (.als)
 *
 * The functions regarding processing of ALS files. This is currently devided in
 * three subsections with appropriate prefixes:
 *
 * (1) Regarding specifically to ALS files and entities:
 * These are prefixed with ALS/als and refer to specific inner structures and
 * functions of the als file and subsequent ALS reinterpretation this program stores.
 *
 * (2) Regarding virtual memory buffer:
 * These are prefixed with VMEM/vmem and are used for working with a virtual memory
 * chunk that is allocated and maintained for the storage of the session that is 
 * analysed.
 */

#ifndef _SESSION_FILE_H_
#define _SESSION_FILE_H_

#include <libxml/encoding.h>
#include <libxml/xmlwriter.h>
#include <libxml/parser.h>
#include <libxml/tree.h>
#include <openssl/evp.h>

/* General defines */

#define ALS_CONTROL_BYTES "ALSDATAFMTTREEFL"
#define ALS_CONTROL_BYTES_LENGTH 16
#define ALS_VERSION_MAJOR 0
#define ALS_VERSION_MINOR 1

#define PATH_INITIAL_SIZE 256
#define VMEM_INITIAL_SIZE 262144

/* ALS related structures */

typedef enum {
  ALS_ELEMENT = 23,
  ALS_DATA
} als_node_type; 

typedef struct _als_attribute {
  uint16_t name_size;
  uint16_t value_size;
  char data[];
} als_attribute;

typedef struct _als_node als_node;

typedef struct _als_element_node {
  uint16_t name_size;
  uint16_t no_attrs;
  uint16_t no_children;
  char data[];
} als_element_node;

typedef struct _als_data_node {
  uint32_t size;
  char data[];
} als_data_node;

struct _als_node {
  uint32_t size;
  char id[16];
  als_node_type type;
  union {
    als_element_node element;
    als_data_node data;
  };
};

typedef struct {
  uint16_t encoding_size;
  uint16_t version_size;
  char data[];
} als_payload;

typedef struct {
  uint32_t pula;  
} als_index;

typedef struct {
  char control_bytes[ALS_CONTROL_BYTES_LENGTH];
  uint16_t version_major;
  uint16_t version_minor;
  char index_md5[16];
  uint32_t index_size;
  char payload_md5[16];
  uint32_t payload_size;
  char data[];
} als_file;

/* VMEM related structures */

typedef struct {
  uint32_t alloc_size;
  uint32_t used;
  char *p;
} vmem;

typedef struct {
  vmem *mem;
  uint32_t offset;
} vmem_element;

/* Path structures */

/* VMEM macros */

/** 
 * Checks if there is enough space to have an entity of the given size at the 
 * given pointer inside the memory block defined by `mem`.
 * If it's true it returns the specific pointer. If not it first alters the
 * memory block and then returns the pointer.
 */
#define VMEMCHECK(ptr, size, mem) \
           ((ptr)+(size) < (mem)->p + (mem)->alloc_size ? \
            (ptr) : vmem_extend((mem), (ptr)))
/**
 * Tries to cast the location at `ptr` in `mem` as the given type.
 * Uses VMEM_CHECK with sizeof(type).
 */
#define VMEMCAST(type, ptr, mem) \
  ((type *) (VMEM_CHECK(sizeof(type), ptr, mem)))
/**
 * Performes a memcpy but with VMEM_CHECK in the middle
 */
#define VMEMCPY(p, s, size, mem) memcpy((char *) VMEM_CHECK(size, p, mem), s, size)

/* vmem_element to als element macros */

/**
 * Casts a vmem_element `el` to an als of type `type`
 */
#define ALS_EL(type, el) \
  ((type *) (el->mem->p + el->offset))
/* Shorthand functions for the given ALS types */
#define ALS_FILE(el) ALS_EL(als_file, el)
#define ALS_PAYLOAD(el) ALS_EL(als_payload, el)
#define ALS_NODE(el) ALS_EL(als_node, el)
#define ALS_ATTR(el) ALS_EL(als_attribute, el)

#define VMEM_EL(ptr, mem, type) \
  ((vmem_element *) vmem_element_at(ptr, mem, sizeof(type))) 

#define VMEM_FILE(ptr, mem) (VMEM_EL(ptr, mem, als_file))
#define VMEM_PAYLOAD(ptr, mem) (VMEM_EL(ptr, mem, als_payload))
#define VMEM_NODE(ptr, mem) (VMEM_EL(ptr, mem, als_node))
#define VMEM_ATTR(ptr, mem) (VMEM_EL(ptr, mem, als_attribute))

/* DEPRECATED 
#define ALS_CAST(type, el) VMEM_CAST(type, (el->mem->p + el->offset), el->mem)
#define ALS_UPDATE(type, el) ((type *) (el->mem->p + el->offset))
*/


/**
 * Specific ALS element accessor macros based off of vmem_element in order
 * to maintain locality when and if the data buffer is reallocated and moved
 */

/*
 * ===================================================================
 * als_attribute getter/setter macros.
 * ===================================================================
 * Explicit getters 
 */
#define ALS_ATTR_NAME_SIZE(el)  ( ALS_ATTR(el)->name_size  )
#define ALS_ATTR_VALUE_SIZE(el) ( ALS_ATTR(el)->value_size )
#define ALS_ATTR_DATA(el)       ( ALS_ATTR(el)->data       )
/*
 * Implicit getters
 */
#define ALS_ATTR_NAME(el)  ((char *) ALS_ATTR(el)->data)
#define ALS_ATTR_VALUE(el) ((char *) (ALS_ATTR(el)->data + ALS_ATTR_NAME_SIZE(el)))
#define ALS_ATTR_SIZE(el)  ( sizeof(uint16_t) * 2 + \
                             sizeof(char) * ( ALS_ATTR_NAME_SIZE(el) + \
                                              ALS_ATTR_VALUE_SIZE(el) ))
/*
 * Explicit setters
 */
#define ALS_ATTR_SET_NAME_SIZE(el, sz) (ALS_ATTR(el)->name_size = sz)
#define ALS_ATTR_SET_VALUE_SIZE(el,sz) (ALS_ATTR(el)->value_size = sz)
/*
 * Implicit setters
 */
#define ALS_NODE_SET_NAME(el, nm, len) \
  do { ALS_ATTR_SET_NAME_SIZE(el, len); \
       VMEMCPY(ALS_ATTR_NAME(el), nm, len, el->mem); } while(false)
#define ALS_NODE_SET_VALUE(el, vl, len) \
  do { ALS_ATTR_SET_VALUE_SIZE(el, len); \
       VMEMCPY(ALS_ATTR_VALUE(el), vl, len, el->mmem); } while(false)
/*
 * ===================================================================
 * als_node getter/setter macros
 * ===================================================================
 * Explicit getters
 */
#define ALS_NODE_SIZE(el) (ALS_NODE(el)->size)
#define ALS_NODE_ID(el)   (ALS_NODE(el)->id  )
#define ALS_NODE_TYPE(el) (ALS_NODE(el)->type)
/* als_element_node */
#define ALS_NODE_NAME_SIZE(el)   (ALS_NODE(el)->element.name_size  )
#define ALS_NODE_NO_ATTRS(el)    (ALS_NODE(el)->element.no_attrs   )
#define ALS_NODE_NO_CHILDREN(el) (ALS_NODE(el)->element.no_children)
#define ALS_NODE_EL_DATA(el)     (ALS_NODE(el)->element.data       )
/* als_data_node */
#define ALS_NODE_DATA_SIZE(el)   (ALS_NODE(el)->data.size)
#define ALS_NODE_DATA(el)        (ALS_NODE(el)->data.data)
/**
 * Implicit getters
 */
#define ALS_NODE_NAME(el) ((char *) ALS_NODE_EL_DATA(el))
#define ALS_NODE_ATTR_OFFSETS_PTR(el) (ALS_NODE_EL_DATA(el) + ALS_NODE_NAME_SIZE(el))
#define ALS_NODE_ATTR_OFFSETS(el) \
  ((uint32_t *) ALS_NODE_ATTR_OFFSETS_PTR(el))
#define ALS_NODE_ATTR_OFFSET(el, i) \
  ((uint32_t) ALS_NODE_ATTR_OFFSETS(el)[i])
#define ALS_NODe_ATTR_PTR(el, i) \
  (ALS_NODE_EL_DATA(el) + ALS_NODE_ATTR_OFFSET(el, i))
#define ALS_NODE_ATTR(el, i) \
  (VMEM_ATTR(ALS_NODE_ATTR_PTR(el, i), el->mem))

#define ALS_NODE_CHILD_OFFSETS_PTR(el) \
  (ALS_NODE_ATTR_OFFSETS_PTR(el) + sizeof(uint32_t) * ALS_NODE_NO_ATTRS(el))
#define ALS_NODE_CHILD_OFFSETS(el) \
  ((uint32_t *) ALS_NODE_CHILD_OFFSETS_PTR(el))
#define ALS_NODE_CHILD_OFFSET(el, i) \
  ((uint32_t) ALS_NODE_ATTR_OFFSETS(el)[i])
#define ALS_NODE_CHILD_PTR(el, i) \
  (ALS_NODE_EL_DATA(el) + ALS_NODE_CHILD_OFFSET(el, i))
#define ALS_NODE_CHILD(el, i) \
  (VMEM_NODE(ALS_NODE_CHILD_PTR(el, i), el->mem))
/*
 * Explicit setters
 */
#define ALS_NODE_SET_SIZE(el, sz) (ALS_NODE(el)->size = sz)
#define ALS_NODE_SET_TYPE(el, tp) (ALS_NODE(el)->type = tp)
#define ALS_NODE_SET_NAME_SIZE(el, sz)   (ALS_NODE(el)->element.name_size   = sz)
#define ALS_NODE_SET_NO_ATTRS(el, na)    (ALS_NODE(el)->element.no_attrs    = na)
#define ALS_NODE_SET_NO_CHILDREN(el, nc) (ALS_NODE(el)->element.no_children = nc)
#define ALS_NODe_SET_DATA_SIZE(el, ds) (ALS_NODE(el)->data.size = ds)
#define ALS_NODE_SET_ID(el, id) \
  (memcpy(ALS_NODE_ID(el), id, 16))
/**
 * Implicit setters
 */
#define ALS_NODE_SET_NAME(el, nm, len)                            \
  do { ALS_NODE_SET_NAME_SIZE(el, len);                           \
       VMEMCPY(ALS_NODE_NAME(el), nm, len, el->mem); } while(false)

#define ALS_NODE_INIT_ATTR(el, i) \
  do { if (i == 0) { /* FIRST ATTR */                             \
    uint32_t *offsets = (uint32_t *) VMEMCHECK(                   \
              ALS_NODE_ATTR_OFFSETS_PTR(el),                      \
              sizeof(uint32_t) * ALS_NODE_NO_ATTRS(el), el->mem); \
    offsets[0] = sizeof(uint32_t) * ( ALS_NODE_NO_ATTRS(el) +     \
                                    ALS_NODE_NO_CHILDREN(el) );   \
  } else {                                                        \
    uint32_t *offsets = ALS_NODE_ATTR_OFFSETS(el);                \
    vmem_element *prev_attr = ALS_NODE_ATTR(el, (i-1))            \
    offsets[i] = offsets[i-1] + ALS_ATTR_SIZE(prev_attr);         \
    free(prev_attr);                                              \
  }

#define ALS_NODE_INIT_CHILD(el, i) \
  do { if (i == 0) { /* FIRST CHILD */                            \
    uint32_t *offsets = (uint32_t *) VMEMCHECK(                   \
              ALS_NODE_CHILD_OFFSETS_PTR(el),                     \
              sizeof(uint32_t) * ALS_NODE_NO_CHILDREN(el),        \
              el->mem);                                           \
    if (ALS_NODE_NO_ATTRS(el) == 0) { /* NO_ATTRIBUTES */         \
      offsets[0] = sizeof(uint32_t) * ALS_NODE_NO_CHILDREN(el);   \
    } else {                                                      \
      vmem_element *last_attr =                                   \
          ALS_NODE_ATTR(el, ALS_NODE_NO_ATTRS(el)-1);             \
      offsets[0] =                                                \
           ALS_NODE_ATTR_OFFSET(el, ALS_NODE_NO_ATTRS(el)-1) +    \
           ALS_ATTR_SIZE(last_attr);                              \
      free(last_attr);                                            \
    }                                                             \
  } else {                                                        \
    uint32_t *offsets = ALS_NODE_CHILD_OFFSETS(el);               \
    vmem_element *prev_child = ALS_NODE_CHILD(el, (i-1))          \
    offsets[i] = offsets[i-1] + ALS_NODE_SIZE(prev_child);        \
    free(prev_child);                                             \
  }


/**
 * ========================================================================
 * als_payload setter/getter macros 
 * ========================================================================
 * Explicit getters
 */
#define ALS_PAYLOAD_ENCODING_SIZE(el) (ALS_PAYLOAD(el)->encoding_size)
#define ALS_PAYLOAD_VERSION_SIZE(el)  (ALS_PAYLOAD(el)->version_size)
#define ALS_PAYLOAD_DATA(el)          (ALS_PAYLOAD(el)->data)
/**
 * Implicit getters
 */
#define ALS_PAYLOAD_SIZE(el) \
  ((uint32_t) 2*sizeof(uint16_t) + \
              sizeof(char) * ( ALS_PAYLOAD_ENCODING_SIZE(el) + \
                               ALS_PAYLOAD_VERSION_SIZE(el) ) + \
#define ALS_PAYLOAD_ENCODING(el) ((char *) ALS_PAYLOAD_DATA(el))
#define ALS_PAYLOAD_VERSION(el)  ((char *) (ALS_PAYLOAD_DATA(el) + \
                                            ALS_PAYLOAD_ENCODING_SIZE(el)))
#define ALS_PAYLOAD_ROOT_PTR(el) \
   ( ALS_PAYLOAD_VERSION(el) + ALS_PAYLOAD_VERSION_SIZE(el) )
#define ALS_PAYLOAD_ROOT(el) \
  (VMEM_NODE(ALS_PAYLOAD_ROOT_PTR(el), el->mem))

#define ALS_PAYLOAD_SIZE(el) \
  ((uint32_t) 2*sizeof(uint16_t) + \
              sizeof(char) * ( ALS_PAYLOAD_ENCODING_SIZE(el) + \
                               ALS_PAYLOAD_VERSION_SIZE(el) ) + \
              ALS_NODE(ALS_PAYLOAD_ROOT_PTR(el))->size
/**
 * Explicit setters
 */
#define ALS_PAYLOAD_SET_ENCODING_SIZE(el, sz) \
   (ALS_PAYLOAD(el)->encoding_size = sz)
#define ALS_PAYLOAD_SET_VERSION_SIZE(el, sz) \
   (ALS_PAYLOAD(el)->version_size = sz)
/**
 * Implicit setters
 */
#define ALS_PAYLOAD_SET_ENCODING(el, en, len) \
  do { ALS_PAYLOAD_SET_ENCODING_SIZE(el, len); \
       VMEMCPY(ALS_PAYLOAD_ENCODING(el), en, len, el->mem); } while(false)
#define ALS_PAYLOAD_SET_VERSION(el, vs, len) \
  do { ALS_PAYLOAD_SET_VERSION_SIZE(el, len); \
       VMEMCPY(ALS_PAYLOAD_VERSION(el), vs, len, el->mem); } while(false)


/**
 * ========================================================================
 * als_file getter/setter macros 
 * ========================================================================
 * Explicit getters
 */
#define ALS_FILE_CONTROL_BYTES(el) (ALS_FILE(el)->control_bytes)
#define ALS_FILE_VERSION_MAJOR(el) (ALS_FILE(el)->version_major)
#define ALS_FILE_VERSION_MINOR(el) (ALS_FILE(el)->version_minor)
#define ALS_FILE_INDEX_MD5(el)     (ALS_FILE(el)->index_md5)
#define ALS_FILE_INDEX_SIZE(el)    (ALS_FILE(el)->index_size)
#define ALS_FILE_PAYLOAD_MD5(el)   (ALS_FILE(el)->payload_md5)
#define ALS_FILE_PAYLOAD_SIZE(el)  (ALS_FILE(el)->payload_size)
#define ALS_FILE_DATA(el)          (ALS_FILE(el)->data)
/**
 * Implicit getters
 */
#define ALS_FILE_PAYLOAD_PTR(el) (ALS_FILE_DATA(el))
#define ALS_FILE_INDEX_PTR(el)   (ALS_FILE_DATA(el) + ALS_FILE_PAYLOAD_SIZE(el))
#define ALS_FILE_PAYLOAD(el) \
    (VMEM_PAYLOAD(ALS_FILE_PAYLOAD_PTR(el), el->mem))
/**
 * TODO: Decide how to handle the index.
 */
#define ALS_FILE_INDEX(el) \
    (NULL)
/**
 * Explicit setters
 */
#define ALS_FILE_SET_CONTROL_BYTES(el) \
  (memcpy(ALS_FILE_CONTROL_BYTES(el), ALS_CONTROL_BYTES, ALS_CONTROL_BYTES_LENGTH))
#define ALS_FILE_SET_VERSION_MAJOR(el, vm) (ALS_FILE(el)->version_major = vm)
#define ALS_FILE_SET_VERSION_MINOR(el, vm) (ALS_FILE(el)->version_minor = vm)
#define ALS_FILE_SET_INDEX_SIZE(el, sz) (ALS_FILE(el)->index_size = sz)
#define ALS_FILE_SET_PAYLOAD_SIZE(el, sz) (ALS_FILE(el)->payload_size = sz)

/* ALS functions */
void als_load_xml(); 
//void als_write_session_to_file(als_file *als, char * storage_file); 
void als_parse_node(vmem_element *node, xmlNode *xml_node, 
                    EVP_MD_CTX *path, als_node_type type);
void als_set_header(vmem_element *file);

/* Path manipulation functions */
vmem *path_init(char *content, uint32_t size);
void path_push(vmem *path, vmem_element *node);
void path_pop(vmem *path);
void path_destroy(vmem *path);
char *path_element(vmem_element *node);

/* VMEM manipulation functions */
vmem *vmem_init(uint32_t size);
void vmem_cpy(char *dest, char *source, uint32_t size, vmem *mem);
char *vmem_extend(vmem *mem, char *p);
void vmem_attr_init_offset(vmem_element *node, int attr_index);
void vmem_child_init_offset(vmem_element *node, int child_index);
vmem_element *vmem_element_at(char *p, vmem *mem, uint32_t size);

#endif