nbt.c
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#include "nbt.h"
ssize_t loadDB(const char* filename, void** data);
void destroyTag(Tag* t);
void destroyTagList(TagList* l);
void destroyTagCompound(TagCompound* tc);
size_t getTypeSize(uint8_t type);
unsigned int parseList(void* addr, TagList* tl, uint8_t type);
unsigned int parseCompound(void* addr, TagCompound* tc);
unsigned int parsePayload(void* addr,Tag* t);
unsigned int parseTag(void* addr, Tag* t);
ssize_t loadDB(const char* filename, void** data) {
if(access(filename,R_OK) == -1) {
perror("Can't access file");
return -1;
}
struct stat sb;
unsigned int pos = 0;
int fd = open(filename,O_RDONLY);
if(fd == -1) {
perror("Can't open file");
return -2;
}
fstat(fd, &sb);
uint16_t header = 0;
if(pread(fd,&header,sizeof(uint16_t),0) == -1) {
perror("Unable to read header");
close(fd);
return -3;
}
void* filedata;
ssize_t filesize = sb.st_size;
if(header == GZIP_MAGIC) {
close(fd);
filedata = calloc(GZIP_BUFFER,sizeof(char));
gzFile file = gzopen(filename,"r");
if(!file) {
perror("Failed to gzopen() file");
free(filedata);
return -4;
}
int err;
int nRead;
size_t totalBytes = 0;
while((nRead = gzread(file, filedata+totalBytes, GZIP_BUFFER)) != 0) {
totalBytes += nRead;
if(!(totalBytes % GZIP_BUFFER)) {
void* newptr = realloc(filedata,totalBytes + GZIP_BUFFER);
if(newptr == NULL) {
perror("Unable to realloc for decompression");
gzclose(file);
free(filedata);
return -6;
}
filedata = newptr;
}
}
if(!gzeof(file)) {
const char * errorStr;
errorStr = gzerror(file, &err);
fprintf(stderr, "libz error: %s.\n", errorStr);
gzclose(file);
free(filedata);
return -5;
}
filesize = totalBytes;
gzclose (file);
} else {
filedata = malloc(filesize);
ssize_t nRead = 0;
size_t totalRead = 0;
while((nRead = read(fd,filedata+totalRead,filesize-totalRead))) {
if(nRead == -1) {
if(errno == EINTR) {
continue;
}
perror("Error reading file");
return -7;
}
totalRead += nRead;
}
}
*data = filedata;
return filesize;
}
void destroyTag(Tag* t) {
if(t->nameLength) {
free(t->name);
}
if(t->type == TAG_BYTEARRAY || t->type == TAG_INTARRAY || t->type == TAG_LIST) {
destroyTagList((TagList*)t->payload);
} else if(t->type == TAG_COMPOUND) {
destroyTagCompound((TagCompound*)t->payload);
}
if(t->payloadLength) {
free(t->payload);
}
}
void destroyTagList(TagList* l) {
for(int i = 0; i < l->size; ++i) {
destroyTag(&l->list[i]);
}
}
void destroyTagCompound(TagCompound* tc) {
for(int i = 0; i < tc->numTags; ++i) {
destroyTag(&tc->list[i]);
}
}
size_t getTypeSize(uint8_t type) {
switch(type) {
case TAG_BYTE:
return sizeof(uint8_t);
break;
case TAG_SHORT:
return sizeof(uint16_t);
break;
case TAG_INT:
return sizeof(uint32_t);
break;
case TAG_LONG:
return sizeof(uint64_t);
break;
case TAG_FLOAT:
return sizeof(float);
break;
case TAG_DOUBLE:
return sizeof(double);
break;
default:
break;
}
return 0;
}
unsigned int parseList(void* addr, TagList* tl, uint8_t type) {
void* pos = addr;
if(type == TAG_LIST) {
tl->type = *((uint8_t*)pos);
pos += sizeof(uint8_t);
} else if(type == TAG_BYTEARRAY) {
tl->type = TAG_BYTE;
} else if(type == TAG_INTARRAY) {
tl->type = TAG_INT;
}
tl->size = __bswap_32(*((uint32_t*)pos));
pos += sizeof(uint32_t);
tl->list = NULL;
if(tl->type != TAG_END) {
tl->list = calloc(tl->size,sizeof(Tag));
for(int i = 0; i < tl->size; ++i) {
Tag *t = &tl->list[i];
t->type = tl->type;
t->name = NULL;
t->nameLength = 0;
pos += parsePayload(pos,t);
}
}
return pos - addr;
}
unsigned int parseCompound(void* addr, TagCompound* tc) {
void* pos = addr;
unsigned int numTags = 0;
Tag* list = calloc(REALLOC_SIZE,sizeof(Tag));
do {
if(numTags && !(numTags % REALLOC_SIZE)) {
void* newptr = reallocarray(list, numTags + REALLOC_SIZE, sizeof(Tag));
if(!newptr) {
fprintf(stderr,"Unable to request memory realloc\n");
break;
}
list = newptr;
}
pos += parseTag(pos,&list[numTags]);
} while(list[numTags++].type != TAG_END);
tc->list = list;
tc->numTags = numTags-1;
return pos - addr;
}
unsigned int parsePayload(void* addr,Tag* t) {
void* pos = addr;
t->payloadLength = getTypeSize(t->type); // initially, then particularly for lists/compounds/strings
TagCompound* tc;
TagList *tl;
uint16_t u16 = 0;
uint32_t u32 = 0;
uint64_t u64 = 0;
switch(t->type) {
case TAG_BYTE:
t->payload = calloc(1,t->payloadLength);
memcpy(t->payload,pos,t->payloadLength);
pos += t->payloadLength;
break;
case TAG_SHORT:
u16 = __bswap_16(*(uint16_t*)pos);
t->payload = calloc(1,t->payloadLength);
memcpy(t->payload,&u16,t->payloadLength);
pos += t->payloadLength;
break;
case TAG_INT:
case TAG_FLOAT:
u32 = __bswap_32(*(uint32_t*)pos);
t->payload = calloc(1,t->payloadLength);
memcpy(t->payload,&u32,t->payloadLength);
pos += t->payloadLength;
break;
case TAG_LONG:
case TAG_DOUBLE:
u64 = __bswap_64(*(uint64_t*)pos);
t->payload = calloc(1,t->payloadLength);
memcpy(t->payload,&u64,t->payloadLength);
pos += t->payloadLength;
break;
case TAG_STRING:
t->payloadLength = __bswap_16(*((uint16_t*)pos));
t->payload = NULL;
if(t->payloadLength) {
t->payload = calloc(t->payloadLength,sizeof(char));
memcpy(t->payload,pos+sizeof(uint16_t),t->payloadLength);
}
pos += sizeof(uint16_t) + t->payloadLength;
break;
case TAG_COMPOUND:
tc = (TagCompound*)calloc(1,sizeof(TagCompound));
t->payloadLength = sizeof(sizeof(TagCompound));
t->payload = tc;
pos += parseCompound(pos,tc);
break;
case TAG_LIST:
case TAG_BYTEARRAY:
case TAG_INTARRAY:
tl = (TagList*)calloc(1,sizeof(TagList));
t->payloadLength = sizeof(sizeof(TagList));
t->payload = tl;
pos += parseList(pos,tl,t->type);
break;
}
return pos - addr;
}
unsigned int parseTag(void* addr, Tag* t) {
void* pos = addr;
t->type = *((uint8_t*)pos);
t->nameLength = 0;
t->payloadLength = 0;
pos += sizeof(uint8_t);
if(t->type != TAG_END) {
t->nameLength = __bswap_16(*((uint16_t*)pos));
t->name = NULL;
if(t->nameLength) {
t->name = calloc(t->nameLength,sizeof(char));
memcpy(t->name,pos+sizeof(uint16_t),t->nameLength);
}
pos += sizeof(uint16_t) + t->nameLength;
}
pos += parsePayload(pos,t);
return pos-addr;
}