/*
 * Copyright (C) 2011 Andrea Mazzoleni
 *
 * This program 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.
 *
 * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "portable.h"

#include "elem.h"
#include "handle.h"

/****************************************************************************/
/* handle */

int handle_create(struct snapraid_handle* handle, struct snapraid_file* file)
{
	struct stat st;
	int ret;

	/* if already opened, nothing to do */
	if (handle->file == file && handle->f != -1) {
		return 0;
	}

	/* close if already open */
	if (handle->f != -1) {
		ret = close(handle->f);
		if (ret != 0) {
			fprintf(stderr, "Error closing file '%s'. %s.\n", handle->file->sub, strerror(errno));
			exit(EXIT_FAILURE);
		}
	}

	snprintf(handle->path, sizeof(handle->path), "%s%s", handle->disk->dir, file->sub);
	handle->f = open(handle->path, O_RDWR | O_CREAT | O_BINARY, 0600);

	if (handle->f == -1) {
		fprintf(stderr, "Error opening file '%s'. %s.\n", handle->path, strerror(errno));
		exit(EXIT_FAILURE);
	}

	/* just opened */
	handle->file = file;

	/* set the size */
	ret = fstat(handle->f, &st);
	if (ret != 0) {
		fprintf(stderr, "Error accessing file '%s'. %s.\n", handle->path, strerror(errno));
		exit(EXIT_FAILURE);
	}

	if (st.st_size < file->size) {
#if HAVE_POSIX_FALLOCATE
		/* allocate real space */
		ret = posix_fallocate(handle->f, 0, file->size);
#else
		/* allocate using a sparse file */
		ret = ftruncate(handle->f, file->size);
#endif
		if (ret != 0) {
			if (errno == ENOSPC) {
				fprintf(stderr, "Failed to grow file '%s' due lack of space.\n", handle->path);
			} else {
				fprintf(stderr, "Error growing file '%s'. %s.\n", handle->path, strerror(errno));
			}
				exit(EXIT_FAILURE);
		}
	} else if (st.st_size > file->size) {
		ret = ftruncate(handle->f, file->size);
		if (ret != 0) {
			fprintf(stderr, "Error truncating file '%s'. %s.\n", handle->path, strerror(errno));
			exit(EXIT_FAILURE);
		}
	}

#if HAVE_POSIX_FADVISE
	/* advise sequential access */
	ret = posix_fadvise(handle->f, 0, 0, POSIX_FADV_SEQUENTIAL);
	if (ret != 0) {
		fprintf(stderr, "Error advising file '%s'. %s.\n", handle->path, strerror(errno));
		exit(EXIT_FAILURE);
	}
#endif

	return 0;
}

int handle_open(int ret_on_error, struct snapraid_handle* handle, struct snapraid_file* file)
{
	int ret;

	/* if already opened, nothing to do */
	if (handle->file == file && handle->f != -1) {
		return 0;
	}

	/* close if already open */
	if (handle->f != -1) {
		ret = close(handle->f);
		if (ret != 0) {
			/* here we always abort on error, as close is supposed to never fail */
			fprintf(stderr, "Error closing file '%s'. %s.\n", handle->file->sub, strerror(errno));
			exit(EXIT_FAILURE);
		}
	}

	snprintf(handle->path, sizeof(handle->path), "%s%s", handle->disk->dir, file->sub);
	handle->f = open(handle->path, O_RDONLY | O_BINARY);

	if (handle->f == -1) {
		/* invalidate for error */
		handle->file = 0;
		handle->f = -1;

		if (ret_on_error)
			return ret_on_error;

		fprintf(stderr, "Error opening file '%s'. %s.\n", handle->path, strerror(errno));
		exit(EXIT_FAILURE);
	}

	/* just opened */
	handle->file = file;

#if HAVE_POSIX_FADVISE
	/* advise sequential access */
	ret = posix_fadvise(handle->f, 0, 0, POSIX_FADV_SEQUENTIAL);
	if (ret != 0) {
		/* here we always abort on error, as advise is supposed to never fail */
		fprintf(stderr, "Error advising file '%s'. %s.\n", handle->path, strerror(errno));
		exit(EXIT_FAILURE);
	}
#endif

	return 0;
}

void handle_close(struct snapraid_handle* handle)
{
	int ret;

	if (handle->f != -1) {
		ret = close(handle->f);
		if (ret != 0) {
			fprintf(stderr, "Error closing file '%s'. %s.\n", handle->file->sub, strerror(errno));
			exit(EXIT_FAILURE);
		}
	}

	handle->file = 0;
	handle->f = -1;
}

int handle_read(int ret_on_error, struct snapraid_handle* handle, struct snapraid_block* block, unsigned char* block_buffer, unsigned block_size)
{
	ssize_t read_ret;
	off_t offset;
	unsigned read_size;

	offset = block_file_pos(block) * (off_t)block_size;

	read_size = block_file_size(block, block_size);

	read_ret = pread(handle->f, block_buffer, read_size, offset);
	if (read_ret != read_size) {
		if (ret_on_error)
			return ret_on_error;

		fprintf(stderr, "Error reading file '%s'. %s.\n", handle->path, strerror(errno));
		exit(EXIT_FAILURE);
	}

	return read_size;
}

void handle_write(struct snapraid_handle* handle, struct snapraid_block* block, unsigned char* block_buffer, unsigned block_size)
{
	ssize_t write_ret;
	off_t offset;
	unsigned write_size;

	offset = block_file_pos(block) * (off_t)block_size;

	write_size = block_file_size(block, block_size);

	write_ret = pwrite(handle->f, block_buffer, write_size, offset);
	if (write_ret != write_size) {
		fprintf(stderr, "Error writing file '%s'. %s.\n", handle->path, strerror(errno));
		exit(EXIT_FAILURE);
	}
}