/* SPDX-License-Identifier: GPL-2.0-or-later */

#include "utils.h"

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

#include <errno.h>
#include <limits.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void *xmalloc(size_t size)
{
	void *p = malloc(size);
	if (p == NULL) {
		fprintf(stderr, "Failed to allocate memory\n");
		abort();
	}
	return p;
}

char *to_chars(const CHAR16 uchars[], size_t size)
{
	char *chars = xmalloc(size / 2 + 1);

	const CHAR16 *from = uchars;
	char *to = chars;
	while (*from != 0) {
		CHAR16 uc = *from++;
		if (uc < CHAR_MAX)
			*to++ = uc;
		else
			*to++ = '?';
	}

	// In case there was no terminating NUL.
	if (to != chars && to[-1] != '\0')
		*to = '\0';

	return chars;
}

CHAR16 *to_uchars(const char chars[], size_t *size)
{
	*size = (strlen(chars) + 1) * 2;
	CHAR16 *uchars = xmalloc(*size);

	const char *from = chars;
	CHAR16 *to = uchars;
	while (*from != '\0')
		*to++ = *from++;
	*to = 0;

	return uchars;
}

bool str_eq(const char lhs[], const char rhs[])
{
	return strcmp(lhs, rhs) == 0;
}

struct mem_range_t map_file(const char path[], bool rw)
{
	struct mem_range_t range = {0};

	int open_flags = rw ? O_RDWR : O_RDONLY;
	int mmap_flags = rw ? PROT_READ | PROT_WRITE : PROT_READ;

	int fd = open(path, open_flags);
	if (fd == -1) {
		fprintf(stderr, "Failed to open(): %s\n", strerror(errno));
		return range;
	}

	struct stat stat_buf;
	if (fstat(fd, &stat_buf) != 0) {
		(void)close(fd);
		fprintf(stderr, "Failed to fstat(): %s\n", strerror(errno));
		return range;
	}

	if (stat_buf.st_size == 0) {
		(void)close(fd);
		fprintf(stderr, "Can't map an empty \"%s\" file\n", path);
		return range;
	}

	uint8_t *mem = mmap(/*addr=*/NULL, stat_buf.st_size, mmap_flags,
			    MAP_SHARED | MAP_POPULATE, fd, /*offset=*/0);
	(void)close(fd);
	if (mem == MAP_FAILED) {
		fprintf(stderr, "Failed to mmap(): %s\n", strerror(errno));
		return range;
	}

	range.start = mem;
	range.length = stat_buf.st_size;
	return range;
}

void unmap_file(struct mem_range_t store)
{
	if (munmap(store.start, store.length) != 0)
		fprintf(stderr, "Failed to munmap(): %s\n", strerror(errno));
}