/******************************************************
MariaBackup: hot backup tool for InnoDB
(c) 2009-2013 Percona LLC and/or its affiliates.
Originally Created 3/3/2009 Yasufumi Kinoshita
Written by Alexey Kopytov, Aleksandr Kuzminsky, Stewart Smith, Vadim Tkachenko,
Yasufumi Kinoshita, Ignacio Nin and Baron Schwartz.

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; version 2 of the License.

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, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA

*******************************************************/

/* Source file cursor implementation */

#include <my_global.h>
#include <my_base.h>
#include <fil0fil.h>
#include <fsp0fsp.h>
#include <srv0start.h>
#include <trx0sys.h>

#include "fil_cur.h"
#include "common.h"
#include "read_filt.h"
#include "xtrabackup.h"
#include "xb0xb.h"

/* Size of read buffer in pages (640 pages = 10M for 16K sized pages) */
#define XB_FIL_CUR_PAGES 640

/***********************************************************************
Extracts the relative path ("database/table.ibd") of a tablespace from a
specified possibly absolute path.

For user tablespaces both "./database/table.ibd" and
"/remote/dir/database/table.ibd" result in "database/table.ibd".

For system tablepsaces (i.e. When is_system is TRUE) both "/remote/dir/ibdata1"
and "./ibdata1" yield "ibdata1" in the output. */
const char *
xb_get_relative_path(
/*=================*/
	const char*	path,		/*!< in: tablespace path (either
			  		relative or absolute) */
	ibool		is_system)	/*!< in: TRUE for system tablespaces,
					i.e. when only the filename must be
					returned. */
{
	const char *next;
	const char *cur;
	const char *prev;

	prev = NULL;
	cur = path;

	while ((next = strchr(cur, OS_PATH_SEPARATOR)) != NULL) {

		prev = cur;
		cur = next + 1;
	}

	if (is_system) {

		return(cur);
	} else {

		return((prev == NULL) ? cur : prev);
	}

}

/**********************************************************************//**
Closes a file. */
static
void
xb_fil_node_close_file(
/*===================*/
	fil_node_t*	node)	/*!< in: file node */
{
	ibool	ret;

	mutex_enter(&fil_system->mutex);

	ut_ad(node);
	ut_a(node->n_pending == 0);
	ut_a(node->n_pending_flushes == 0);
	ut_a(!node->being_extended);

	if (!node->is_open()) {

		mutex_exit(&fil_system->mutex);

		return;
	}

	ret = os_file_close(node->handle);
	ut_a(ret);

	node->handle = OS_FILE_CLOSED;

	ut_a(fil_system->n_open > 0);
	fil_system->n_open--;
	fil_n_file_opened--;

	if (node->space->purpose == FIL_TYPE_TABLESPACE &&
	    fil_is_user_tablespace_id(node->space->id)) {

		ut_a(UT_LIST_GET_LEN(fil_system->LRU) > 0);

		/* The node is in the LRU list, remove it */
		UT_LIST_REMOVE(fil_system->LRU, node);
	}

	mutex_exit(&fil_system->mutex);
}

/************************************************************************
Open a source file cursor and initialize the associated read filter.

@return XB_FIL_CUR_SUCCESS on success, XB_FIL_CUR_SKIP if the source file must
be skipped and XB_FIL_CUR_ERROR on error. */
xb_fil_cur_result_t
xb_fil_cur_open(
/*============*/
	xb_fil_cur_t*	cursor,		/*!< out: source file cursor */
	xb_read_filt_t*	read_filter,	/*!< in/out: the read filter */
	fil_node_t*	node,		/*!< in: source tablespace node */
	uint		thread_n)	/*!< thread number for diagnostics */
{
	bool	success;

	/* Initialize these first so xb_fil_cur_close() handles them correctly
	in case of error */
	cursor->orig_buf = NULL;
	cursor->node = NULL;

	cursor->space_id = node->space->id;

	strncpy(cursor->abs_path, node->name, sizeof(cursor->abs_path));

	/* Get the relative path for the destination tablespace name, i.e. the
	one that can be appended to the backup root directory. Non-system
	tablespaces may have absolute paths for DATA DIRECTORY.
	We want to make "local" copies for the backup. */
	strncpy(cursor->rel_path,
		xb_get_relative_path(cursor->abs_path, cursor->is_system()),
		sizeof(cursor->rel_path));

	/* In the backup mode we should already have a tablespace handle created
	by fil_ibd_load() unless it is a system
	tablespace. Otherwise we open the file here. */
	if (cursor->is_system() || srv_operation == SRV_OPERATION_RESTORE_DELTA
	    || xb_close_files) {
		node->handle = os_file_create_simple_no_error_handling(
			0, node->name,
			OS_FILE_OPEN,
			OS_FILE_READ_ALLOW_DELETE, true, &success);
		if (!success) {
			/* The following call prints an error message */
			os_file_get_last_error(TRUE);

			msg("[%02u] mariabackup: error: cannot open "
			    "tablespace %s\n",
			    thread_n, cursor->abs_path);

			return(XB_FIL_CUR_ERROR);
		}
		mutex_enter(&fil_system->mutex);

		fil_system->n_open++;
		fil_n_file_opened++;

		if (node->space->purpose == FIL_TYPE_TABLESPACE &&
		    fil_is_user_tablespace_id(node->space->id)) {

			/* Put the node to the LRU list */
			UT_LIST_ADD_FIRST(fil_system->LRU, node);
		}

		mutex_exit(&fil_system->mutex);
	}

	ut_ad(node->is_open());

	cursor->node = node;
	cursor->file = node->handle;

	if (stat(cursor->abs_path, &cursor->statinfo)) {
		msg("[%02u] mariabackup: error: cannot stat %s\n",
		    thread_n, cursor->abs_path);

		xb_fil_cur_close(cursor);

		return(XB_FIL_CUR_ERROR);
	}

	if (srv_file_flush_method == SRV_O_DIRECT
	    || srv_file_flush_method == SRV_O_DIRECT_NO_FSYNC) {

		os_file_set_nocache(cursor->file, node->name, "OPEN");
	}

	posix_fadvise(cursor->file, 0, 0, POSIX_FADV_SEQUENTIAL);

	/* Determine the page size */
	ulint	flags = xb_get_space_flags(cursor->file);
	if (flags == ULINT_UNDEFINED) {
		xb_fil_cur_close(cursor);
		return(XB_FIL_CUR_SKIP);
	}

	if (!fsp_flags_is_valid(flags, cursor->space_id)) {
		ulint cflags = fsp_flags_convert_from_101(flags);
		if (cflags == ULINT_UNDEFINED) {
			msg("[%02u] mariabackup: Error: Invalid "
			    "tablespace flags: %x.\n", thread_n, uint(flags));
			return(XB_FIL_CUR_SKIP);
		}
		flags = cflags;
	}

	const page_size_t page_size(flags);
	cursor->page_size = page_size;

	/* Allocate read buffer */
	cursor->buf_size = XB_FIL_CUR_PAGES * page_size.physical();
	cursor->orig_buf = static_cast<byte *>
		(malloc(cursor->buf_size + UNIV_PAGE_SIZE));
	cursor->buf = static_cast<byte *>
		(ut_align(cursor->orig_buf, UNIV_PAGE_SIZE));

	cursor->buf_read = 0;
	cursor->buf_npages = 0;
	cursor->buf_offset = 0;
	cursor->buf_page_no = 0;
	cursor->thread_n = thread_n;

	cursor->space_size = (ulint)(cursor->statinfo.st_size
				     / page_size.physical());

	cursor->read_filter = read_filter;
	cursor->read_filter->init(&cursor->read_filter_ctxt, cursor,
				  node->space->id);

	return(XB_FIL_CUR_SUCCESS);
}

/************************************************************************
Reads and verifies the next block of pages from the source
file. Positions the cursor after the last read non-corrupted page.

@return XB_FIL_CUR_SUCCESS if some have been read successfully, XB_FIL_CUR_EOF
if there are no more pages to read and XB_FIL_CUR_ERROR on error. */
xb_fil_cur_result_t
xb_fil_cur_read(
/*============*/
	xb_fil_cur_t*	cursor)	/*!< in/out: source file cursor */
{
	ibool			success;
	byte*			page;
	ulint			i;
	ulint			npages;
	ulint			retry_count;
	xb_fil_cur_result_t	ret;
	ib_int64_t		offset;
	ib_int64_t		to_read;
	const ulint		page_size = cursor->page_size.physical();
	xb_ad(!cursor->is_system() || page_size == UNIV_PAGE_SIZE);

	cursor->read_filter->get_next_batch(&cursor->read_filter_ctxt,
					    &offset, &to_read);

	if (to_read == 0LL) {
		return(XB_FIL_CUR_EOF);
	}

	if (to_read > (ib_int64_t) cursor->buf_size) {
		to_read = (ib_int64_t) cursor->buf_size;
	}

	xb_a(to_read > 0 && to_read <= 0xFFFFFFFFLL);

	if ((to_read & ~(page_size - 1))
	    && offset + to_read == cursor->statinfo.st_size) {

		if (to_read < (ib_int64_t) page_size) {
			msg("[%02u] mariabackup: Warning: junk at the end of "
			    "%s:\n", cursor->thread_n, cursor->abs_path);
			msg("[%02u] mariabackup: Warning: offset = %llu, "
			    "to_read = %llu\n",
			    cursor->thread_n,
			    (unsigned long long) offset,
			    (unsigned long long) to_read);

			return(XB_FIL_CUR_EOF);
		}

		to_read = (ib_int64_t) (((ulint) to_read) &
					~(page_size - 1));
	}

	xb_a((to_read & (page_size - 1)) == 0);

	npages = (ulint) (to_read / cursor->page_size.physical());

	retry_count = 10;
	ret = XB_FIL_CUR_SUCCESS;

read_retry:
	xtrabackup_io_throttling();

	cursor->buf_read = 0;
	cursor->buf_npages = 0;
	cursor->buf_offset = offset;
	cursor->buf_page_no = (ulint)(offset / cursor->page_size.physical());

	FilSpace space(cursor->space_id);

	if (!space()) {
		return(XB_FIL_CUR_ERROR);
	}

	success = os_file_read(IORequestRead,
			       cursor->file, cursor->buf, offset,
			       (ulint) to_read);
	if (!success) {
		return(XB_FIL_CUR_ERROR);
	}

	/* check pages for corruption and re-read if necessary. i.e. in case of
	partially written pages */
	for (page = cursor->buf, i = 0; i < npages;
	     page += page_size, i++) {
		ulint page_no = cursor->buf_page_no + i;

		if (cursor->space_id == TRX_SYS_SPACE &&
		    page_no >= FSP_EXTENT_SIZE &&
		    page_no < FSP_EXTENT_SIZE * 3) {
			/* We ignore the doublewrite buffer pages */
		} else if (!fil_space_verify_crypt_checksum(
				   page, cursor->page_size, space->id, page_no)
			   && buf_page_is_corrupted(true, page,
						    cursor->page_size,
						    space)) {
			retry_count--;
			if (retry_count == 0) {
				msg("[%02u] mariabackup: "
				    "Error: failed to read page after "
				    "10 retries. File %s seems to be "
				    "corrupted.\n", cursor->thread_n,
				    cursor->abs_path);
				ret = XB_FIL_CUR_ERROR;
				break;
			}

			if (retry_count == 9) {
				msg("[%02u] mariabackup: "
				    "Database page corruption detected at page "
				    ULINTPF ", retrying...\n",
				    cursor->thread_n, page_no);
			}

			os_thread_sleep(100000);

			goto read_retry;
		}
		cursor->buf_read += page_size;
		cursor->buf_npages++;
	}

	posix_fadvise(cursor->file, offset, to_read, POSIX_FADV_DONTNEED);

	return(ret);
}

/************************************************************************
Close the source file cursor opened with xb_fil_cur_open() and its
associated read filter. */
void
xb_fil_cur_close(
/*=============*/
	xb_fil_cur_t *cursor)	/*!< in/out: source file cursor */
{
	cursor->read_filter->deinit(&cursor->read_filter_ctxt);

	free(cursor->orig_buf);

	if (cursor->node != NULL) {
		xb_fil_node_close_file(cursor->node);
		cursor->file = OS_FILE_CLOSED;
	}
}