pkg.c

#include <stdlib.h>
#include <stdio.h>
#include "pkg.h"

void FreePkg(pkg p) {
	for (u32 i=0; i<p.filecount; i++)
		free(p.files[i].dat);
	free(p.files);
}

void WritePkg(char *filename, pkg p, u32 max_files) {
	FILE *fp = fopen(filename,"wb");
	finfo *file_info = (finfo*)p.files;
	u32 filecount = p.filecount;
	u32 freefl = max_files - filecount;
	void **data = malloc(filecount*sizeof(void*)); //backup pointers to data

	u64 loc = 2*sizeof(u32)+max_files*sizeof(finfo); //offset into start of data
	for (u32 i=0; i<filecount; i++) {
		data[i] = (void*)file_info[i].location; //save pointer
		file_info[i].location = loc; //set location
		loc += file_info[i].size; //move on
	}

	fwrite(&max_files, 1, sizeof(u32), fp); //write table size
	fwrite(&freefl, 1, sizeof(u32), fp); //how many files are free
	fwrite(file_info, filecount, sizeof(finfo), fp); //write table
	finfo tmp = {0};
	for (u32 i=0; i<freefl; i++)
		fwrite(&tmp, 1, sizeof(finfo), fp); //fill remaining space
	for (u32 i=0; i<filecount; i++)
		fwrite(data[i], file_info[i].size, 1, fp);
	free(data);
	fclose(fp);
}

pkg ReadPkg(char *filename) {
	FILE *fp = fopen(filename,"rb");
	if (!fp) return (pkg){NULL, 0};
	u32 totalf, freef, filecount;
	fread(&totalf, 1, sizeof(u32), fp); //table size
	fread(&freef, 1, sizeof(u32), fp); //free space
	filecount = totalf - freef; //get taken file count

	pfile *files = malloc(filecount*sizeof(pfile)); //get files
	fread(files, filecount, sizeof(pfile), fp); //read taken table
	fseek(fp, freef, SEEK_CUR);
	u64 loc;
	for (u32 i=0; i<filecount; i++) {
		loc = (u64)files[i].dat;
		files[i].dat = malloc(files[i].size);
		fseek(fp, loc, SEEK_SET);
		fread(files[i].dat, files[i].size, 1, fp);
	}

	fclose(fp);
	return (pkg){files, filecount}; //assemble
}

void AddFile(char *package, pfile file) {
	FILE *fp = fopen(package,"r+b");
	if (!fp) return;
	u32 totalf, freef, filecount;
	fread(&totalf, 1, sizeof(u32), fp);
	fread(&freef, 1, sizeof(u32), fp);
	filecount = totalf - freef;
	freef--; //since we're adding a file
	fseek(fp, sizeof(u32), SEEK_SET);
	fwrite(&freef, 1, sizeof(u32), fp); //overwrite free file count
	finfo *table = malloc((filecount+1)*sizeof(finfo)); //1st points to start
	fread(&table[1], filecount, sizeof(finfo), fp); //get table
	table[0] = (finfo){0,2*sizeof(u32)+totalf*sizeof(finfo)};
	filecount++;

	for (u32 i=0; i<filecount; i++) { //find available space
		const u64 end = table[i].location + table[i].size; //where file ends
		u64 space = ~0; //how much free space after file ends
		for (u32 j=1; space && j<filecount; j++)
			if (table[j].location >= end && table[j].location - end < space)
				space = table[j].location - end;
		if (space)
			if (space >= file.size) {
				const void *data = file.dat;
				finfo *header = (finfo*)&file;
				header->location = end; //set the location to byte offset
				fwrite(header, 1, sizeof(finfo), fp);
				fseek(fp, end, SEEK_SET);
				fwrite(data, file.size, 1, fp);
				break;
			}
	}
	free(table);
	fclose(fp);
}

void RmFile(char *package, u64 ID) {
	FILE *fp = fopen(package,"r+b");
	if (!fp) return;
	u32 totalf, freef, filecount;
	fread(&totalf, 1, sizeof(u32), fp);
	fread(&freef, 1, sizeof(u32), fp);
	filecount = totalf - freef;
	freef++; //since we're removing a file
	fseek(fp, sizeof(u32), SEEK_SET);
	fwrite(&freef, 1, sizeof(u32), fp);
	finfo *table = malloc(filecount*sizeof(finfo));
	fread(table, filecount, sizeof(finfo), fp); //get table

	for (u32 i=0; i<filecount; i++)
		if (ID == table[i].ID) { //found the selected file
			filecount--;
			if (i < filecount) {
				fseek(fp, 2*sizeof(u32)+filecount*sizeof(finfo), SEEK_SET);
				fread(table, 1, sizeof(finfo), fp);
				fseek(fp, 2*sizeof(u32)+i*sizeof(finfo), SEEK_SET);
				fwrite(table, 1, sizeof(finfo), fp);
			}
			break;
		}
	free(table);
	fclose(fp);
}