Moved decompression function outside and changed it to work with buffers. Added compression function

Imanol-Mikel Barba Sabariego
1 parent 3f906bc9
Showing 3 changed files with 161 additions and 55 deletions
compression.c
compression.h
nbt.c
+#include "compression.h"
+
+ssize_t inflateGzip(void* compData, size_t compDataLen, void** unCompData) {
+    unsigned int increase = compDataLen/2;
+    unsigned int uncompLength = compDataLen; // Later to be increased
+
+    char* uncomp = (char*)calloc(uncompLength, sizeof(char));
+  
+    z_stream strm;
+    strm.next_in = (Bytef*) compData;
+    strm.avail_in = compDataLen;
+    strm.total_out = 0;
+    strm.zalloc = Z_NULL;
+    strm.zfree = Z_NULL;
+  
+    if (inflateInit2(&strm, (16+MAX_WBITS)) != Z_OK) {
+        fprintf(stderr, "Unable to initialize zlib zstream for decompression\n");
+        free(uncomp);
+        return -1;
+    }  
+  
+    int err = Z_OK;
+    do {
+        // If our output buffer is too small
+        if(strm.total_out >= uncompLength ) {
+            // Increase size of output buffer
+            void* newptr = realloc(uncomp,uncompLength + increase);
+            if(newptr == NULL) {
+                fprintf(stderr,"Unable to request memory realloc\n");
+                inflateEnd(&strm);
+                free(uncomp);
+                return -2;
+            }
+            uncomp = newptr;
+            uncompLength += increase;
+        }
+  
+        strm.next_out = (Bytef *) (uncomp + strm.total_out);
+        strm.avail_out = uncompLength - strm.total_out;
+
+        // Inflate another chunk.
+        err = inflate (&strm, Z_SYNC_FLUSH);
+        if(err != Z_OK && err != Z_STREAM_END) {
+            fprintf(stderr, "zlib error: %d.\n", err);
+            inflateEnd(&strm);
+            free(uncomp);
+            return -3;
+        }
+    } while(err != Z_STREAM_END);
+    uncompLength = strm.total_out;
+
+    if(inflateEnd(&strm) != Z_OK) {
+        fprintf(stderr,"Error while deallocating libz zstream\n");
+        free(uncomp);
+        return -4;
+    }
+
+    *unCompData = uncomp;
+    return uncompLength;
+}
+
+ssize_t deflateGzip(void* unCompData, size_t unCompDataLen, void** compData) {
+    unsigned int compLength = unCompDataLen;
+    unsigned int increase = compLength/4;
+    char* comp = (char*)calloc(compLength, sizeof(char));
+    
+    z_stream strm;
+    strm.next_in = (Bytef*) unCompData;
+    strm.avail_in = unCompDataLen;
+    strm.total_out = 0;
+    strm.zalloc = Z_NULL;
+    strm.zfree = Z_NULL;
+    
+    if(deflateInit2(&strm, Z_DEFAULT_COMPRESSION, Z_DEFLATED, (16+MAX_WBITS),8 , Z_DEFAULT_STRATEGY) != Z_OK) {
+        fprintf(stderr, "Unable to initialize zlib zstream for compression\n");
+        free(comp);
+        return -1;
+    }
+
+    int err = Z_OK;
+    do {
+        // If our output buffer is too small
+        if (strm.total_out >= compLength) {
+            // Increase size of output buffer
+            void* newptr = realloc(comp, compLength + increase);
+            if(newptr == NULL) {
+                fprintf(stderr,"Unable to request memory realloc\n");
+                deflateEnd(&strm);
+                free(comp);
+                return -2;
+            }
+            comp = newptr;
+            compLength += increase;
+        }
+
+        strm.next_out = (Bytef*) (comp + strm.total_out);
+        strm.avail_out = compLength - strm.total_out;
+
+        // deflate another chunk
+        err = deflate(&strm, Z_FINISH);
+        if(err != Z_OK && err != Z_STREAM_END) {
+            fprintf(stderr, "Error while deflating buffer\n");
+            deflateEnd(&strm);
+            free(comp);
+            return -3;
+        }
+    } while(err != Z_STREAM_END);
+    compLength = strm.total_out;
+    
+    if(deflateEnd(&strm) != Z_OK) {
+        fprintf(stderr,"Error while deallocating libz zstream\n");
+        free(comp);
+        return -4;
+    }
+
+    // Set OS Flag to 0x00: "FAT filesystem (MS-DOS, OS/2, NT/Win32)"
+    comp[OS_FLAG_OFFSET] = 0x00;
+
+    *compData = comp;
+    return compLength;
+}
 \ No newline at end of file
+#ifndef _COMPRESSION_H
+#define _COMPRESSION_H
+
+#include <stdlib.h>
+#include <zlib.h>
+#include <stdio.h>
+
+#define OS_FLAG_OFFSET 0x9
+
+ssize_t deflateGzip(void* unCompData, size_t unCompDataLen, void** compData);
+ssize_t inflateGzip(void* compData, size_t compDataLen, void** unCompData);
+
+#endif
 \ No newline at end of file
 #include "nbt.h"
+#include "compression.h"
+#include "chunk.h"
 ssize_t loadDB(const char* filename, void** data);
 void destroyTag(Tag* t);
@@ -26,67 +28,31 @@ ssize_t loadDB(const char* filename, void** data) {
     }
     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;
+    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;
             }
-            totalRead += nRead;
+            perror("Error reading file");
+            return -7;
         }
+        totalRead += nRead;
     }
+
+    if(*(uint16_t*)filedata == GZIP_MAGIC) {
+        void* decompressedFileData;
+        filesize = inflateGzip(filedata,filesize,&decompressedFileData);
+        free(filedata);
+        filedata = decompressedFileData;
+    }
+
     *data = filedata;
     return filesize;
 }
@@ -190,6 +156,12 @@ unsigned int parseCompound(void* addr, TagCompound* tc) {
         pos += parseTag(pos,&list[numTags]);
     } while(list[numTags++].type != TAG_END);
+    void* newptr = reallocarray(list, numTags, sizeof(Tag));
+    if(!newptr) {
+        fprintf(stderr,"Unable to request memory realloc\n");
+    }
+    list = newptr;
+
     tc->list = list;
     tc->numTags = numTags-1;
     return pos - addr;