Abort 6 issues when using memcpy() - c

Question

I am getting Abort 6 error and I have looked it up. I don't see where in my code a strcpy() is used but possibly memcpy() could be the issue? Not sure where and why its happening but it only starting appearing when I implementing the root directory update in the code.
NOTE: I have left out dir.name and will implement later when this other issue resolves.
It prints out the print functions but seems to abort when implementing the root directory code below.
The global file is below:
#include "../sifs.h"
#include "md5.h"
// CONCRETE STRUCTURES AND CONSTANTS USED THROUGHOUT THE SIFS LIBRARY.
// DO NOT CHANGE ANYTHING IN THIS FILE.
#define SIFS_MIN_BLOCKSIZE 1024
#define SIFS_MAX_NAME_LENGTH 32 // including the NULL byte
#define SIFS_MAX_ENTRIES 24 // for both directory and file entries
#define SIFS_UNUSED 'u'
#define SIFS_DIR 'd'
#define SIFS_FILE 'f'
#define SIFS_DATABLOCK 'b'
#define SIFS_ROOTDIR_BLOCKID 0
typedef struct {
size_t blocksize;
uint32_t nblocks;
} SIFS_VOLUME_HEADER;
typedef char SIFS_BIT; // SIFS_UNUSED, SIFS_DIR, ...
typedef uint32_t SIFS_BLOCKID;
// DEFINITION OF EACH DIRECTORY BLOCK - MUST FIT INSIDE A SINGLE BLOCK
typedef struct {
char name[SIFS_MAX_NAME_LENGTH];
time_t modtime; // time last modified <- time()
uint32_t nentries;
struct {
SIFS_BLOCKID blockID; // of the entry's subdirectory or file
uint32_t fileindex; // into a SIFS_FILEBLOCK's filenames[]
} entries[SIFS_MAX_ENTRIES];
} SIFS_DIRBLOCK;
// DEFINITION OF EACH FILE BLOCK - MUST FIT INSIDE A SINGLE BLOCK
typedef struct {
time_t modtime; // time first file added <- time()
size_t length; // length of files' contents in bytes
unsigned char md5[MD5_BYTELEN];
SIFS_BLOCKID firstblockID;
uint32_t nfiles; // n files with identical contents
char filenames[SIFS_MAX_ENTRIES][SIFS_MAX_NAME_LENGTH];
} SIFS_FILEBLOCK;
FILE1.C
#include "sifs-internal.h"
// make a new directory within an existing volume
int SIFS_mkdir(const char *volumename, const char *dirname)
{
FILE *fp = fopen(volumename, "r+");
if(fp != NULL){
//read in the header information
SIFS_VOLUME_HEADER header;
fread(&header,sizeof header,1,fp);
printf("%zu\n", header.blocksize);
printf("%u", header.nblocks);
// Check for vaidty of variables
if (header.nblocks == 0 || header.blocksize < SIFS_MIN_BLOCKSIZE) {
SIFS_errno = SIFS_EINVAL;
return 1;
}
//read in the bitmap information
SIFS_BIT bitmap[header.nblocks];
fseek(fp ,sizeof header, SEEK_SET);
fread(&bitmap, header.nblocks,1,fp);
for (int i = 1; i < header.nblocks; i++){
if (bitmap[i] == SIFS_UNUSED){
bitmap[i] = SIFS_DIR;
// update the root directory
char rootblock[header.blocksize];
SIFS_DIRBLOCK rootdir_block;
fseek(fp, sizeof header + sizeof bitmap, SEEK_SET);
fread(&rootdir_block, header.blocksize,1,fp);
for (int j = 0; j < SIFS_MAX_ENTRIES; j++){
rootdir_block.entries[j].blockID = i;
rootdir_block.nentries += rootdir_block.nentries + 1;
break;
}
//write the new updated root dir into the vol
memset(rootblock, 0, sizeof rootblock);
memcpy(rootblock, &rootdir_block, sizeof(rootdir_block));
fseek(fp ,sizeof header + sizeof bitmap, SEEK_SET);
fwrite(rootblock, sizeof rootblock, 1, fp);
char oneblock[header.blocksize];
time_t now;
SIFS_DIRBLOCK dir;
memset(&dir, 0, sizeof(dir)); // set all to zero
memset(oneblock, 0, sizeof oneblock);
dir.modtime = time(&now);
dir.nentries = 0;
//set the block to 0 and assign memory of dir into block
memcpy(oneblock, &dir, sizeof(dir));
//write the dir data into the volume
fseek(fp ,sizeof header + sizeof bitmap + i * header.blocksize, SEEK_SET);
fwrite(oneblock, sizeof oneblock, 1, fp);
//memset(oneblock, 0, sizeof oneblock);
//Update the bitmap
fseek(fp ,sizeof header, SEEK_SET);
fwrite(bitmap, sizeof bitmap, 1, fp);
fclose(fp);
return 0;
}
}
}
SIFS_errno = SIFS_ENOTYET;
return 1;
}