Fixing bugs and changing chunk interface to something more sensible (8ea36403) | Commits | Imanol-Mikel Barba Sabariego / libnbt

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Commit 8ea3640398f7d39378ee8b64ecf67fa701265eaf

Authored by Imanol-Mikel Barba Sabariego 2020-05-29 23:30:03 +0100

1 parent 6f9d59b6

Fixing bugs and changing chunk interface to something more sensible

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Showing 2 changed files with 226 additions and 0 deletions

chunk.c 0 → 100644

View file @8ea3640

	1	+#include "chunk.h"
	2	+
	3	+RegionID translateChunkToRegion(int x, int z);
	4	+RegionID translateCoordsToRegion(double x, double y, double z);
	5	+ChunkID translateCoordsToChunk(double x, double y, double z);
	6	+int overwriteChunk(const char* regionFolder, ChunkID chunk, void* chunkData, size_t chunkLength);
	7	+ssize_t loadChunk(const char* regionFolder, ChunkID chunk, void** chunkData);
	8	+
	9	+RegionID translateChunkToRegion(int x, int z) {
	10	+ RegionID region;
	11	+ region.x = x/CHUNKS_PER_REGION;
	12	+ region.z = z/CHUNKS_PER_REGION;
	13	+ return region;
	14	+}
	15	+
	16	+RegionID translateCoordsToRegion(double x, double y, double z) {
	17	+ ChunkID chunk = translateCoordsToChunk(x,y,z);
	18	+ return translateChunkToRegion(chunk.x,chunk.z);
	19	+}
	20	+
	21	+ChunkID translateCoordsToChunk(double x, double y, double z) {
	22	+ ChunkID chunk;
	23	+ chunk.x = x/BLOCKS_PER_CHUNK;
	24	+ chunk.z = z/BLOCKS_PER_CHUNK;
	25	+ return chunk;
	26	+}
	27	+
	28	+int overwriteChunk(const char* regionFolder, ChunkID chunk, void* chunkData, size_t chunkLength) {
	29	+ RegionID region = translateChunkToRegion(chunk.x,chunk.z);
	30	+ ChunkID relativeChunk;
	31	+ relativeChunk.x = chunk.x % 32;
	32	+ relativeChunk.z = chunk.z % 32;
	33	+
	34	+ char* regionFilename = calloc(MAX_REGION_FILENAME_LENGTH + strlen(regionFolder),sizeof(char));
	35	+ sprintf(regionFilename,"%s/r.%d.%d.mca.new",regionFolder,region.x,region.z);
	36	+
	37	+ if(access(regionFilename,R_OK \| W_OK) == -1) {
	38	+ fprintf(stderr,"Can't access file %s: %s\n",regionFilename,strerror(errno));
	39	+ return -1;
	40	+ }
	41	+
	42	+ int fd = open(regionFilename,O_RDWR);
	43	+ if(fd == -1) {
	44	+ fprintf(stderr,"Unable to open region file %s: %s\n",regionFilename,strerror(errno));
	45	+ return -2;
	46	+ }
	47	+ free(regionFilename);
	48	+
	49	+ uint32_t chunkHeaderOffset;
	50	+ if(pread(fd,&chunkHeaderOffset,sizeof(uint32_t),(relativeChunk.x + relativeChunk.z * CHUNK_OFFSET_LENGTH) * sizeof(uint32_t)) == -1) {
	51	+ close(fd);
	52	+ fprintf(stderr,"Unable to read chunk header offset: %s\n",strerror(errno));
	53	+ return -3;
	54	+ }
	55	+ uint32_t totalChunkLength = (chunkHeaderOffset >> 24) * 4096;
	56	+ chunkHeaderOffset = (__bswap_32(chunkHeaderOffset & 0x00FFFFFF) >> 8) * CHUNK_SECTOR_SIZE;
	57	+ int pos = lseek(fd,chunkHeaderOffset,SEEK_SET);
	58	+ if(pos == -1) {
	59	+ close(fd);
	60	+ fprintf(stderr,"Unable to seek to header offset: %s\n",strerror(errno));
	61	+ return -4;
	62	+ }
	63	+
	64	+ ChunkHeader header;
	65	+ if(pread(fd,&header,sizeof(ChunkHeader),pos) <= 0) {
	66	+ close(fd);
	67	+ fprintf(stderr,"Unable to read chunk header: %s\n",strerror(errno));
	68	+ return -5;
	69	+ }
	70	+ header.length = __bswap_32(header.length);
	71	+
	72	+ void* compressedChunk;
	73	+ ssize_t compressedChunkLength = deflateGzip(chunkData,chunkLength,&compressedChunk,(header.compressionType == COMPRESSION_TYPE_ZLIB));
	74	+ if(compressedChunkLength > totalChunkLength) {
	75	+ // insert new 4096 blocks
	76	+ }
	77	+ header.length = __bswap_32((uint32_t)compressedChunkLength+1);
	78	+ if(write(fd,&header,sizeof(ChunkHeader)) <= 0) {
	79	+ close(fd);
	80	+ free(compressedChunk);
	81	+ fprintf(stderr,"Unable to read chunk header: %s\n",strerror(errno));
	82	+ return -6;
	83	+ }
	84	+ ssize_t nWritten = 0;
	85	+ size_t totalWritten = 0;
	86	+
	87	+ while((nWritten = write(fd,compressedChunk+totalWritten,compressedChunkLength-totalWritten))) {
	88	+ if(nWritten == -1) {
	89	+ if(errno == EINTR) {
	90	+ continue;
	91	+ }
	92	+ fprintf(stderr,"Unable to write chunk: %s\n",strerror(errno));
	93	+ close(fd);
	94	+ free(compressedChunk);
	95	+ return -7;
	96	+ }
	97	+ totalWritten += nWritten;
	98	+ }
	99	+ close(fd);
	100	+ free(compressedChunk);
	101	+ return 0;
	102	+}
	103	+
	104	+ssize_t loadChunk(const char* regionFolder, ChunkID chunk, void** chunkData) {
	105	+ RegionID region = translateChunkToRegion(chunk.x,chunk.z);
	106	+ ChunkID relativeChunk;
	107	+ relativeChunk.x = chunk.x % 32;
	108	+ relativeChunk.z = chunk.z % 32;
	109	+
	110	+ char* regionFilename = calloc(MAX_REGION_FILENAME_LENGTH + strlen(regionFolder),sizeof(char));
	111	+ sprintf(regionFilename,"%s/r.%d.%d.mca",regionFolder,region.x,region.z);
	112	+
	113	+ if(access(regionFilename,R_OK) == -1) {
	114	+ fprintf(stderr,"Can't access file %s: %s\n",regionFilename,strerror(errno));
	115	+ return -1;
	116	+ }
	117	+
	118	+ int fd = open(regionFilename,O_RDONLY);
	119	+ if(fd == -1) {
	120	+ fprintf(stderr,"Unable to open region file %s: %s\n",regionFilename,strerror(errno));
	121	+ return -2;
	122	+ }
	123	+ free(regionFilename);
	124	+
	125	+ uint32_t chunkHeaderOffset;
	126	+ if(pread(fd,&chunkHeaderOffset,sizeof(uint32_t),(relativeChunk.x + relativeChunk.z * CHUNK_OFFSET_LENGTH) * sizeof(uint32_t)) == -1) {
	127	+ close(fd);
	128	+ fprintf(stderr,"Unable to read chunk header offset: %s\n",strerror(errno));
	129	+ return -3;
	130	+ }
	131	+ chunkHeaderOffset = (__bswap_32(chunkHeaderOffset & 0x00FFFFFF) >> 8) * CHUNK_SECTOR_SIZE;
	132	+
	133	+ if(lseek(fd,chunkHeaderOffset,SEEK_SET) == -1) {
	134	+ close(fd);
	135	+ fprintf(stderr,"Unable to seek to header offset: %s\n",strerror(errno));
	136	+ return -4;
	137	+ }
	138	+
	139	+ ChunkHeader header;
	140	+ if(read(fd,&header,sizeof(ChunkHeader)) <= 0) {
	141	+ close(fd);
	142	+ fprintf(stderr,"Unable to read chunk header: %s\n",strerror(errno));
	143	+ return -5;
	144	+ }
	145	+ header.length = __bswap_32(header.length);
	146	+ ssize_t chunkLength = header.length;
	147	+
	148	+ void* compressedChunk = calloc(chunkLength,sizeof(char));
	149	+ ssize_t nRead = 0;
	150	+ size_t totalRead = 0;
	151	+
	152	+ while((nRead = read(fd,compressedChunk+totalRead,chunkLength-totalRead))) {
	153	+ if(nRead == -1) {
	154	+ if(errno == EINTR) {
	155	+ continue;
	156	+ }
	157	+ fprintf(stderr,"Unable to read chunk: %s\n",strerror(errno));
	158	+ close(fd);
	159	+ free(compressedChunk);
	160	+ return -6;
	161	+ }
	162	+ totalRead += nRead;
	163	+ }
	164	+ close(fd);
	165	+
	166	+ void *decompressedChunk;
	167	+ chunkLength = inflateGzip(compressedChunk,chunkLength,&decompressedChunk,(header.compressionType == COMPRESSION_TYPE_ZLIB));
	168	+
	169	+ if(chunkLength <= 0) {
	170	+ fprintf(stderr,"Error while decompressing chunk\n");
	171	+ return -8;
	172	+ }
	173	+ free(compressedChunk);
	174	+
	175	+ *chunkData = decompressedChunk;
	176	+ return chunkLength;
	177	+}
0	178	\ No newline at end of file
...	...

chunk.h 0 → 100644

View file @8ea3640

	1	+#ifndef _CHUNK_H
	2	+#define _CHUNK_H
	3	+
	4	+#include <stdlib.h>
	5	+#include <unistd.h>
	6	+#include <stdio.h>
	7	+#include <errno.h>
	8	+#include <fcntl.h>
	9	+#include <stdint.h>
	10	+#include <string.h>
	11	+#include <byteswap.h>
	12	+
	13	+#include "compression.h"
	14	+
	15	+#define BLOCKS_PER_CHUNK 16
	16	+#define CHUNKS_PER_REGION 32
	17	+#define CHUNK_OFFSET_LENGTH 32
	18	+#define CHUNK_SECTOR_SIZE 4096
	19	+
	20	+// 58593 is the maximum number of regions containing 32 chunks in any direction
	21	+// Thus, biggest filename is:
	22	+// r.-58593.-58593.mca
	23	+#define MAX_REGION_FILENAME_LENGTH 32 // Just to round up
	24	+
	25	+enum COMPRESSION_TYPE {
	26	+ COMPRESSION_TYPE_GZIP = 1,
	27	+ COMPRESSION_TYPE_ZLIB = 2
	28	+};
	29	+
	30	+typedef struct RegionID {
	31	+ int x;
	32	+ int z;
	33	+} RegionID;
	34	+
	35	+typedef struct ChunkID {
	36	+ int x;
	37	+ int z;
	38	+} ChunkID;
	39	+
	40	+typedef struct __attribute__((packed)) ChunkHeader {
	41	+ uint32_t length;
	42	+ uint8_t compressionType;
	43	+} ChunkHeader;
	44	+
	45	+ChunkID translateCoordsToChunk(double x, double y, double z);
	46	+int overwriteChunk(const char* regionFolder, ChunkID chunk, void* chunkData, size_t chunkLength);
	47	+ssize_t loadChunk(const char* regionFolder, ChunkID chunk, void** chunkData);
	48	+
	49	+#endif
0	50	\ No newline at end of file
...	...

Imanol-Mikel Barba Sabariego / libnbt · Commits

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Fixing bugs and changing chunk interface to something more sensible