/* file.c - file I/O functions */
/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 2002,2006,2007,2009  Free Software Foundation, Inc.
 *
 *  GRUB is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *(at your option) any later version.
 *
 *  GRUB is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with GRUB.  If not, see <https://www.gnu.org/licenses/>.
 */

#include <grub/misc.h>
#include <grub/err.h>
#include <grub/file.h>
#include <grub/mm.h>
#include <grub/fs.h>
#include <grub/device.h>
#include <grub/term.h>

GRUB_EXPORT(grub_file_get_device_name);
GRUB_EXPORT(grub_file_open);
GRUB_EXPORT(grub_file_read);
GRUB_EXPORT(grub_file_seek);
GRUB_EXPORT(grub_file_close);

GRUB_EXPORT(grub_file_pb_init);
GRUB_EXPORT(grub_file_pb_fini);
GRUB_EXPORT(grub_file_pb_show);
GRUB_EXPORT(grub_file_pb_read);

/* Get the device part of the filename NAME. It is enclosed by parentheses.  */
char *
grub_file_get_device_name(const char *name) {
	if (name[0] == '(') {
		const char *p = strchr (name, ')');
		char *ret;

		if (!p) {
			grub_error (GRUB_ERR_BAD_FILENAME, "missing `)'");
			return 0;
		}

		ret = (char *)grub_malloc (p - name);
		if (!ret) {
			return 0;
		}

		grub_memcpy (ret, name + 1, p - name - 1);
		ret[p - name - 1] = '\0';
		return ret;
	}

	return 0;
}

grub_file_t
grub_file_open(const char *name) {
	grub_device_t device;
	grub_file_t file = 0;
	char *device_name;
	const char *file_name;

	device_name = grub_file_get_device_name (name);
	if (grub_errno) {
		return 0;
	}

	/* Get the file part of NAME.  */
	file_name = strchr (name, ')');
	if (file_name) {
		file_name++;
	} else {
		file_name = (char *)name;
	}

	device = grub_device_open (device_name);
	grub_free (device_name);
	if (!device) {
		goto fail;
	}

	file = (grub_file_t)grub_zalloc (sizeof (*file));
	if (!file) {
		goto fail;
	}

	file->device = device;

	if (device->disk && file_name[0] != '/') {
		/* This is a block list.  */
		file->fs = &grub_fs_blocklist;
	} else {
		file->fs = grub_fs_probe (device);
		if (!file->fs) {
			goto fail;
		}
	}

	if ((file->fs->open) (file, file_name) != GRUB_ERR_NONE) {
		goto fail;
	}

	return file;

fail:
	if (device) {
		grub_device_close (device);
	}

	/* if (net) grub_net_close (net);  */

	grub_free (file);

	return 0;
}

grub_ssize_t
grub_file_read(grub_file_t file, void *buf, grub_size_t len) {
	grub_ssize_t res;

	if (file->offset > file->size) {
		grub_error (GRUB_ERR_OUT_OF_RANGE,
			"attempt to read past the end of file");
		return -1;
	}

	if (len == 0 || len > file->size - file->offset) {
		len = file->size - file->offset;
	}

	/* Prevent an overflow.  */
	if ((grub_ssize_t)len < 0) {
		len >>= 1;
	}

	if (len == 0) {
		return 0;
	}

	res = (file->fs->read) (file, buf, len);
	if (res > 0) {
		file->offset += res;
	}

	return res;
}

grub_err_t
grub_file_close(grub_file_t file) {
	if (file->fs->close) {
		(file->fs->close) (file);
	}

	if (file->device) {
		grub_device_close (file->device);
	}
	grub_free (file);
	return grub_errno;
}

grub_off_t
grub_file_seek(grub_file_t file, grub_off_t offset) {
	grub_off_t old;

	if (offset > file->size) {
		grub_error (GRUB_ERR_OUT_OF_RANGE,
			"attempt to seek outside of the file");
		return -1;
	}

	old = file->offset;
	file->offset = offset;
	return old;
}

static void
grub_file_pb_show_default(int num,
	int total) {
	grub_printf (".");
	grub_refresh ();
}

static void
grub_file_pb_fini_default(void) {
	grub_printf ("\n");
}

void(*grub_file_pb_init)(void);
void(*grub_file_pb_fini)(void) = grub_file_pb_fini_default;
void(*grub_file_pb_show)(int num, int total) = grub_file_pb_show_default;

grub_ssize_t
grub_file_pb_read(grub_file_t file, void *b, grub_size_t len, int total) {
	grub_ssize_t ret;
	grub_size_t bsize;
	int num;
	char *buf = b;

	if ((len < GRUB_FILE_PB_MIN_SIZE) || (total == 0)) {
		return grub_file_read (file, buf, len);
	}

	ret = 0;
	if (grub_file_pb_init) {
		grub_file_pb_init ();
	}

	bsize = ((len / total) + 511) &(~511);
	num = 0;
	while (len > 0) {
		grub_size_t n;
		grub_ssize_t r;

		grub_file_pb_show (num, total);

		n = (len > bsize)? bsize: len;
		r = grub_file_read (file, buf, n);
		if (r <= 0) {
			if (ret == 0) {
				ret = -1;
			}
			break;
		}

		buf += r;
		len -= r;
		ret += r;
		num++;
	}

	if (grub_file_pb_fini) {
		grub_file_pb_fini ();
	}
	return ret;
}