#include <stdio.h>
#include <errno.h>
#include <ctype.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <stdint.h>
#include <time.h>
#include <sys/stat.h>

#include "lint.h"

struct hmt *
open_file(char *filename, int readonly)
{
	struct hmt *hmt;
	struct stat st;
	char *ext;
	uint16_t magic;

	if (!(hmt = malloc(sizeof(struct hmt))))
	{
		perror("malloc");
		return NULL;
	}

	if (debug)
		printf("Opening file '%s' (readonly=%d)\n", filename, readonly);

	strcpy(hmt->fname, filename);

	if ((ext = strrchr(hmt->fname, '.')))
	{
		ext++;
		if (debug)
			printf("    Extension: '%s'", ext);

		if (strcmp(ext, "hmt"))
		{
			*ext = '\0';
			strcat(hmt->fname, "hmt");
		}
	}
	else
		strcat(hmt->fname, ".hmt");

	if (debug)
		printf("  Actual: '%s'\n", hmt->fname);

	if (stat(hmt->fname, &st) == -1)
	{
		perror(hmt->fname);
		free(hmt);
		return NULL;
	}

	hmt->binsize = st.st_size;

	if (debug)
		printf("Opening %s, %lu bytes.\n", hmt->fname,
		    (unsigned long)hmt->binsize);

	hmt->readonly = readonly;

	if ((hmt->fd = open(hmt->fname, readonly ? O_RDONLY : O_RDWR, 0)) == -1)
	{
		perror(hmt->fname);
		free(hmt);
		return NULL;
	}

	hmt->bin = (uint8_t *)mmap(NULL, hmt->binsize,
	    readonly ? PROT_READ : PROT_READ|PROT_WRITE,
	    MAP_SHARED, hmt->fd, 0);
	if (hmt->bin == MAP_FAILED)
	{
		if (debug)
			printf("mmap() failed, falling back to read.\n");
		/* This occurs if the underlying filesystem does not support
		 * mmap, e.g. NTFS. Fallback to holding the file in memory.
		 */
		if (!(hmt->bin = (uint8_t *)malloc(hmt->binsize)))
		{
			perror("malloc");
			free(hmt);
			close(hmt->fd);
			return NULL;
		}
		read(hmt->fd, hmt->bin, hmt->binsize);
		hmt->mmapped = 0;
	}
	else
	{
		if (debug)
			printf("File mapped into memory.\n");
		hmt->mmapped = 1;
	}

	magic = read_uint16(hmt->bin, 0);

	if (magic != 0x1701)
	{
		printf("Invalid HMT file, %s\n", hmt->fname);
		close_file(hmt);
		return NULL;
	}

	hmt->modified = 0;
	parse_hmt(hmt);

	return hmt;
}

void
close_file(struct hmt *hmt)
{
	if (debug)
		printf("Closing file.\n");

	if (hmt->mmapped)
		munmap((void *)hmt->bin, hmt->binsize);
	else
	{
		if (hmt->modified && !hmt->readonly)
		{
			lseek(hmt->fd, SEEK_SET, 0);
			write(hmt->fd, hmt->bin, hmt->binsize);
		}
		free(hmt->bin);
	}
	if (hmt->fd > 0)
		close(hmt->fd);
	hmt->fd = -1;
}