#include <sys/stat.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <stddef.h>
#include <unistd.h>
#include "s8slice.h"

#include <stdio.h>

enum {
	OS_READ  = 1<<0,
	OS_WRITE = 1<<1,
	OS_ALLFLAGS = (1<<2)-1
};
typedef unsigned int os_open_flags;

S8Slice os_open_file(S8Slice path, os_open_flags flags)
{
	int oflag = 0;
	switch (flags & (OS_ALLFLAGS)) {
		case OS_READ:
			oflag = O_RDONLY;
			break;
		case OS_WRITE:
			oflag = O_WRONLY;
			break;
		case OS_READ | OS_WRITE:
			oflag = O_RDWR;
	}
	int fd = open((const char*)path.data, oflag);
	if (fd == -1) {
		goto open_fail;
	}

	struct stat st;
	int ok = fstat(fd, &st);
	if (ok == -1) {
		goto fstat_fail;
	}
	
	int prot = 0;
	if (flags & OS_READ)  prot |= PROT_READ;
	if (flags & OS_WRITE) prot |= PROT_WRITE;
	void *x = mmap(NULL, st.st_size, prot, MAP_SHARED, fd, 0);
	if (x == MAP_FAILED) {
		goto mmap_fail;
	}

	close(fd);

	return (S8Slice){.data = x, .len = (int64_t)st.st_size};

mmap_fail:
fstat_fail:
	close(fd);
open_fail:
	return (S8Slice){.len = -1, .data = (uint8_t*)"<open_file error type>"};
}