CringeDB/System Abstraction/linux/cdb_file.c

#include "../cdb_system.h"
#define _GNU_SOURCE
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/errno.h>
#include <sys/file.h>
#include <fcntl.h>

struct sys_File_impl{
	void * memory;
	size_t length;
	int fd;
};

sys_File sys_fileOpenInMem(char * fileName, unsigned long parameter) {
	int flags = O_RDWR;
	if(parameter & SYS_FILE_NEW) flags |= O_CREAT | O_EXCL;
	int fd = open(fileName, flags, S_IRWXU);
	if(fd == -1) return NULL;

	if(flock(fd, LOCK_EX | LOCK_NB)) {
		close(fd);
		return NULL;
	}

	struct stat info;
	if(stat(fileName, &info)) {
		close(fd);
		return NULL;
	}

	if((parameter & SYS_FILE_TEMP) == SYS_FILE_TEMP) unlink(fileName);

	if(info.st_size == 0) {
		write(fd, "", 1);
		info.st_size++;
	}

	void *mem = mmap(NULL, info.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);

	if(mem == MAP_FAILED) {
		close(fd);
		return NULL;
	}

	sys_File file = (sys_File) sys_heapAlloc(sizeof(struct sys_File_impl));
	file->memory = mem;
	file->length = info.st_size;
	file->fd = fd;
	return file;
}

void * sys_fileFileToMemory(sys_File file) {
	return file->memory;
}

sys_Bool sys_fileExists(char * fileName) {
	struct stat bro;
	return !stat(fileName, &bro);
}

void sys_fileClose(sys_File file) {
	if(file->memory != NULL) {
		msync(file->memory, file->length, MS_SYNC);
		munmap(file->memory, file->length);
		close(file->fd);
	}

	sys_heapFree(file);
}

void sys_fileFlush(sys_File file) {
	msync(file->memory, file->length, MS_SYNC);
}

void * sys_fileResize(sys_File file, signed long appendBytes) {
	size_t newSize = file->length + appendBytes;
	lseek(file->fd, newSize - 1, SEEK_SET);
	write(file->fd, "", 1);

	munmap(file->memory, file->length);
	void *newMem = mmap(NULL, newSize, PROT_READ | PROT_WRITE, MAP_SHARED, file->fd, 0);
	if(newMem == MAP_FAILED) {
		sys_fileClose(file);
		file->fd = 0;
		file->length = 0;
		file->memory = NULL;
		return NULL;
	}

	file->length = newSize;
	file->memory = newMem;
	return newMem;
}

void sys_fileDelete(char * fileName) {
	unlink(fileName);
}

void sys_fileRename(char * fileName, char * newFileName) {
	link(fileName, newFileName);
	unlink(fileName);
}