fileio.c - external_rsync - Gitiles

 /*
  * File IO utilities used in rsync.
  *
  * Copyright (C) 1998 Andrew Tridgell
  * Copyright (C) 2002 Martin Pool
  * Copyright (C) 2004-2020 Wayne Davison
  *
  * 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, visit the http://fsf.org website.
  */

 #include "rsync.h"
 #include "inums.h"

 #ifndef ENODATA
 #define ENODATA EAGAIN
 #endif

 /* We want all reads to be aligned on 1K boundaries. */
 #define ALIGN_BOUNDARY 1024
 /* How far past the boundary is an offset? */
 #define ALIGNED_OVERSHOOT(oft) ((oft) & (ALIGN_BOUNDARY-1))
 /* Round up a length to the next boundary */
 #define ALIGNED_LENGTH(len) ((((len) - 1) | (ALIGN_BOUNDARY-1)) + 1)

 extern int sparse_files;

 OFF_T preallocated_len = 0;

 static OFF_T sparse_seek = 0;
 static OFF_T sparse_past_write = 0;

 int sparse_end(int f, OFF_T size)
 {
 	int ret;

 	sparse_past_write = 0;

 	if (!sparse_seek)
 		return 0;

 #ifdef HAVE_FTRUNCATE
 	ret = do_ftruncate(f, size);
 #else
 	if (do_lseek(f, sparse_seek-1, SEEK_CUR) != size-1)
 		ret = -1;
 	else {
 		do {
 			ret = write(f, "", 1);
 		} while (ret < 0 && errno == EINTR);

 		ret = ret <= 0 ? -1 : 0;
 	}
 #endif

 	sparse_seek = 0;

 	return ret;
 }

 /* Note that the offset is just the caller letting us know where
  * the current file position is in the file. The use_seek arg tells
  * us that we should seek over matching data instead of writing it. */
 static int write_sparse(int f, int use_seek, OFF_T offset, const char *buf, int len)
 {
 	int l1 = 0, l2 = 0;
 	int ret;

 	for (l1 = 0; l1 < len && buf[l1] == 0; l1++) {}
 	for (l2 = 0; l2 < len-l1 && buf[len-(l2+1)] == 0; l2++) {}

 	sparse_seek += l1;

 	if (l1 == len)
 		return len;

 	if (sparse_seek) {
 		if (sparse_past_write >= preallocated_len) {
 			if (do_lseek(f, sparse_seek, SEEK_CUR) < 0)
 				return -1;
 		} else if (do_punch_hole(f, sparse_past_write, sparse_seek) < 0) {
 			sparse_seek = 0;
 			return -1;
 		}
 	}
 	sparse_seek = l2;
 	sparse_past_write = offset + len - l2;

 	if (use_seek) {
 		/* The in-place data already matches. */
 		if (do_lseek(f, len - (l1+l2), SEEK_CUR) < 0)
 			return -1;
 		return len;
 	}

 	while ((ret = write(f, buf + l1, len - (l1+l2))) <= 0) {
 		if (ret < 0 && errno == EINTR)
 			continue;
 		sparse_seek = 0;
 		return ret;
 	}

 	if (ret != (int)(len - (l1+l2))) {
 		sparse_seek = 0;
 		return l1+ret;
 	}

 	return len;
 }

 static char *wf_writeBuf;
 static size_t wf_writeBufSize;
 static size_t wf_writeBufCnt;

 int flush_write_file(int f)
 {
 	int ret = 0;
 	char *bp = wf_writeBuf;

 	while (wf_writeBufCnt > 0) {
 		if ((ret = write(f, bp, wf_writeBufCnt)) < 0) {
 			if (errno == EINTR)
 				continue;
 			return ret;
 		}
 		wf_writeBufCnt -= ret;
 		bp += ret;
 	}
 	return ret;
 }

 /* write_file does not allow incomplete writes.  It loops internally
  * until len bytes are written or errno is set.  Note that use_seek and
  * offset are only used in sparse processing (see write_sparse()). */
 int write_file(int f, int use_seek, OFF_T offset, const char *buf, int len)
 {
 	int ret = 0;

 	while (len > 0) {
 		int r1;
 		if (sparse_files > 0) {
 			int len1 = MIN(len, SPARSE_WRITE_SIZE);
 			r1 = write_sparse(f, use_seek, offset, buf, len1);
 			offset += r1;
 		} else {
 			if (!wf_writeBuf) {
 				wf_writeBufSize = WRITE_SIZE * 8;
 				wf_writeBufCnt  = 0;
 				wf_writeBuf = new_array(char, wf_writeBufSize);
 			}
 			r1 = (int)MIN((size_t)len, wf_writeBufSize - wf_writeBufCnt);
 			if (r1) {
 				memcpy(wf_writeBuf + wf_writeBufCnt, buf, r1);
 				wf_writeBufCnt += r1;
 			}
 			if (wf_writeBufCnt == wf_writeBufSize) {
 				if (flush_write_file(f) < 0)
 					return -1;
 				if (!r1 && len)
 					continue;
 			}
 		}
 		if (r1 <= 0) {
 			if (ret > 0)
 				return ret;
 			return r1;
 		}
 		len -= r1;
 		buf += r1;
 		ret += r1;
 	}
 	return ret;
 }

 /* An in-place update found identical data at an identical location. We either
  * just seek past it, or (for an in-place sparse update), we give the data to
  * the sparse processor with the use_seek flag set. */
 int skip_matched(int fd, OFF_T offset, const char *buf, int len)
 {
 	OFF_T pos;

 	if (sparse_files > 0) {
 		if (write_file(fd, 1, offset, buf, len) != len)
 			return -1;
 		return 0;
 	}

 	if (flush_write_file(fd) < 0)
 		return -1;

 	if ((pos = do_lseek(fd, len, SEEK_CUR)) != offset + len) {
 		rsyserr(FERROR_XFER, errno, "lseek returned %s, not %s",
 			big_num(pos), big_num(offset));
 		return -1;
 	}

 	return 0;
 }

 /* This provides functionality somewhat similar to mmap() but using read().
  * It gives sliding window access to a file.  mmap() is not used because of
  * the possibility of another program (such as a mailer) truncating the
  * file thus giving us a SIGBUS. */
 struct map_struct *map_file(int fd, OFF_T len, int32 read_size, int32 blk_size)
 {
 	struct map_struct *map;

 	map = new0(struct map_struct);

 	if (blk_size && (read_size % blk_size))
 		read_size += blk_size - (read_size % blk_size);

 	map->fd = fd;
 	map->file_size = len;
 	map->def_window_size = ALIGNED_LENGTH(read_size);

 	return map;
 }


 /* slide the read window in the file */
 char *map_ptr(struct map_struct *map, OFF_T offset, int32 len)
 {
 	OFF_T window_start, read_start;
 	int32 window_size, read_size, read_offset, align_fudge;

 	if (len == 0)
 		return NULL;
 	if (len < 0) {
 		rprintf(FERROR, "invalid len passed to map_ptr: %ld\n",
 			(long)len);
 		exit_cleanup(RERR_FILEIO);
 	}

 	/* in most cases the region will already be available */
 	if (offset >= map->p_offset && offset+len <= map->p_offset+map->p_len)
 		return map->p + (offset - map->p_offset);

 	/* nope, we are going to have to do a read. Work out our desired window */
 	align_fudge = (int32)ALIGNED_OVERSHOOT(offset);
 	window_start = offset - align_fudge;
 	window_size = map->def_window_size;
 	if (window_start + window_size > map->file_size)
 		window_size = (int32)(map->file_size - window_start);
 	if (window_size < len + align_fudge)
 		window_size = ALIGNED_LENGTH(len + align_fudge);

 	/* make sure we have allocated enough memory for the window */
 	if (window_size > map->p_size) {
 		map->p = realloc_array(map->p, char, window_size);
 		map->p_size = window_size;
 	}

 	/* Now try to avoid re-reading any bytes by reusing any bytes from the previous buffer. */
 	if (window_start >= map->p_offset && window_start < map->p_offset + map->p_len
 	 && window_start + window_size >= map->p_offset + map->p_len) {
 		read_start = map->p_offset + map->p_len;
 		read_offset = (int32)(read_start - window_start);
 		read_size = window_size - read_offset;
 		memmove(map->p, map->p + (map->p_len - read_offset), read_offset);
 	} else {
 		read_start = window_start;
 		read_size = window_size;
 		read_offset = 0;
 	}

 	if (read_size <= 0) {
 		rprintf(FERROR, "invalid read_size of %ld in map_ptr\n",
 			(long)read_size);
 		exit_cleanup(RERR_FILEIO);
 	}

 	if (map->p_fd_offset != read_start) {
 		OFF_T ret = do_lseek(map->fd, read_start, SEEK_SET);
 		if (ret != read_start) {
 			rsyserr(FERROR, errno, "lseek returned %s, not %s",
 				big_num(ret), big_num(read_start));
 			exit_cleanup(RERR_FILEIO);
 		}
 		map->p_fd_offset = read_start;
 	}
 	map->p_offset = window_start;
 	map->p_len = window_size;

 	while (read_size > 0) {
 		int32 nread = read(map->fd, map->p + read_offset, read_size);
 		if (nread <= 0) {
 			if (!map->status)
 				map->status = nread ? errno : ENODATA;
 			/* The best we can do is zero the buffer -- the file
 			 * has changed mid transfer! */
 			memset(map->p + read_offset, 0, read_size);
 			break;
 		}
 		map->p_fd_offset += nread;
 		read_offset += nread;
 		read_size -= nread;
 	}

 	return map->p + align_fudge;
 }

 int unmap_file(struct map_struct *map)
 {
 	int	ret;

 	if (map->p) {
 		free(map->p);
 		map->p = NULL;
 	}
 	ret = map->status;
 #if 0 /* I don't think we really need this. */
 	force_memzero(map, sizeof map[0]);
 #endif
 	free(map);

 	return ret;
 }
	/*
	* File IO utilities used in rsync.
	*
	* Copyright (C) 1998 Andrew Tridgell
	* Copyright (C) 2002 Martin Pool
	* Copyright (C) 2004-2020 Wayne Davison
	*
	* 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, visit the http://fsf.org website.
	*/

	#include "rsync.h"
	#include "inums.h"

	#ifndef ENODATA
	#define ENODATA EAGAIN
	#endif

	/* We want all reads to be aligned on 1K boundaries. */
	#define ALIGN_BOUNDARY 1024
	/* How far past the boundary is an offset? */
	#define ALIGNED_OVERSHOOT(oft) ((oft) & (ALIGN_BOUNDARY-1))
	/* Round up a length to the next boundary */
	#define ALIGNED_LENGTH(len) ((((len) - 1) \| (ALIGN_BOUNDARY-1)) + 1)

	extern int sparse_files;

	OFF_T preallocated_len = 0;

	static OFF_T sparse_seek = 0;
	static OFF_T sparse_past_write = 0;

	int sparse_end(int f, OFF_T size)
	{
	int ret;

	sparse_past_write = 0;

	if (!sparse_seek)
	return 0;

	#ifdef HAVE_FTRUNCATE
	ret = do_ftruncate(f, size);
	#else
	if (do_lseek(f, sparse_seek-1, SEEK_CUR) != size-1)
	ret = -1;
	else {
	do {
	ret = write(f, "", 1);
	} while (ret < 0 && errno == EINTR);

	ret = ret <= 0 ? -1 : 0;
	}
	#endif

	sparse_seek = 0;

	return ret;
	}

	/* Note that the offset is just the caller letting us know where
	* the current file position is in the file. The use_seek arg tells
	* us that we should seek over matching data instead of writing it. */
	static int write_sparse(int f, int use_seek, OFF_T offset, const char *buf, int len)
	{
	int l1 = 0, l2 = 0;
	int ret;

	for (l1 = 0; l1 < len && buf[l1] == 0; l1++) {}
	for (l2 = 0; l2 < len-l1 && buf[len-(l2+1)] == 0; l2++) {}

	sparse_seek += l1;

	if (l1 == len)
	return len;

	if (sparse_seek) {
	if (sparse_past_write >= preallocated_len) {
	if (do_lseek(f, sparse_seek, SEEK_CUR) < 0)
	return -1;
	} else if (do_punch_hole(f, sparse_past_write, sparse_seek) < 0) {
	sparse_seek = 0;
	return -1;
	}
	}
	sparse_seek = l2;
	sparse_past_write = offset + len - l2;

	if (use_seek) {
	/* The in-place data already matches. */
	if (do_lseek(f, len - (l1+l2), SEEK_CUR) < 0)
	return -1;
	return len;
	}

	while ((ret = write(f, buf + l1, len - (l1+l2))) <= 0) {
	if (ret < 0 && errno == EINTR)
	continue;
	sparse_seek = 0;
	return ret;
	}

	if (ret != (int)(len - (l1+l2))) {
	sparse_seek = 0;
	return l1+ret;
	}

	return len;
	}

	static char *wf_writeBuf;
	static size_t wf_writeBufSize;
	static size_t wf_writeBufCnt;

	int flush_write_file(int f)
	{
	int ret = 0;
	char *bp = wf_writeBuf;

	while (wf_writeBufCnt > 0) {
	if ((ret = write(f, bp, wf_writeBufCnt)) < 0) {
	if (errno == EINTR)
	continue;
	return ret;
	}
	wf_writeBufCnt -= ret;
	bp += ret;
	}
	return ret;
	}

	/* write_file does not allow incomplete writes. It loops internally
	* until len bytes are written or errno is set. Note that use_seek and
	* offset are only used in sparse processing (see write_sparse()). */
	int write_file(int f, int use_seek, OFF_T offset, const char *buf, int len)
	{
	int ret = 0;

	while (len > 0) {
	int r1;
	if (sparse_files > 0) {
	int len1 = MIN(len, SPARSE_WRITE_SIZE);
	r1 = write_sparse(f, use_seek, offset, buf, len1);
	offset += r1;
	} else {
	if (!wf_writeBuf) {
	wf_writeBufSize = WRITE_SIZE * 8;
	wf_writeBufCnt = 0;
	wf_writeBuf = new_array(char, wf_writeBufSize);
	}
	r1 = (int)MIN((size_t)len, wf_writeBufSize - wf_writeBufCnt);
	if (r1) {
	memcpy(wf_writeBuf + wf_writeBufCnt, buf, r1);
	wf_writeBufCnt += r1;
	}
	if (wf_writeBufCnt == wf_writeBufSize) {
	if (flush_write_file(f) < 0)
	return -1;
	if (!r1 && len)
	continue;
	}
	}
	if (r1 <= 0) {
	if (ret > 0)
	return ret;
	return r1;
	}
	len -= r1;
	buf += r1;
	ret += r1;
	}
	return ret;
	}

	/* An in-place update found identical data at an identical location. We either
	* just seek past it, or (for an in-place sparse update), we give the data to
	* the sparse processor with the use_seek flag set. */
	int skip_matched(int fd, OFF_T offset, const char *buf, int len)
	{
	OFF_T pos;

	if (sparse_files > 0) {
	if (write_file(fd, 1, offset, buf, len) != len)
	return -1;
	return 0;
	}

	if (flush_write_file(fd) < 0)
	return -1;

	if ((pos = do_lseek(fd, len, SEEK_CUR)) != offset + len) {
	rsyserr(FERROR_XFER, errno, "lseek returned %s, not %s",
	big_num(pos), big_num(offset));
	return -1;
	}

	return 0;
	}

	/* This provides functionality somewhat similar to mmap() but using read().
	* It gives sliding window access to a file. mmap() is not used because of
	* the possibility of another program (such as a mailer) truncating the
	* file thus giving us a SIGBUS. */
	struct map_struct *map_file(int fd, OFF_T len, int32 read_size, int32 blk_size)
	{
	struct map_struct *map;

	map = new0(struct map_struct);

	if (blk_size && (read_size % blk_size))
	read_size += blk_size - (read_size % blk_size);

	map->fd = fd;
	map->file_size = len;
	map->def_window_size = ALIGNED_LENGTH(read_size);

	return map;
	}


	/* slide the read window in the file */
	char map_ptr(struct map_struct map, OFF_T offset, int32 len)
	{
	OFF_T window_start, read_start;
	int32 window_size, read_size, read_offset, align_fudge;

	if (len == 0)
	return NULL;
	if (len < 0) {
	rprintf(FERROR, "invalid len passed to map_ptr: %ld\n",
	(long)len);
	exit_cleanup(RERR_FILEIO);
	}

	/* in most cases the region will already be available */
	if (offset >= map->p_offset && offset+len <= map->p_offset+map->p_len)
	return map->p + (offset - map->p_offset);

	/* nope, we are going to have to do a read. Work out our desired window */
	align_fudge = (int32)ALIGNED_OVERSHOOT(offset);
	window_start = offset - align_fudge;
	window_size = map->def_window_size;
	if (window_start + window_size > map->file_size)
	window_size = (int32)(map->file_size - window_start);
	if (window_size < len + align_fudge)
	window_size = ALIGNED_LENGTH(len + align_fudge);

	/* make sure we have allocated enough memory for the window */
	if (window_size > map->p_size) {
	map->p = realloc_array(map->p, char, window_size);
	map->p_size = window_size;
	}

	/* Now try to avoid re-reading any bytes by reusing any bytes from the previous buffer. */
	if (window_start >= map->p_offset && window_start < map->p_offset + map->p_len
	&& window_start + window_size >= map->p_offset + map->p_len) {
	read_start = map->p_offset + map->p_len;
	read_offset = (int32)(read_start - window_start);
	read_size = window_size - read_offset;
	memmove(map->p, map->p + (map->p_len - read_offset), read_offset);
	} else {
	read_start = window_start;
	read_size = window_size;
	read_offset = 0;
	}

	if (read_size <= 0) {
	rprintf(FERROR, "invalid read_size of %ld in map_ptr\n",
	(long)read_size);
	exit_cleanup(RERR_FILEIO);
	}

	if (map->p_fd_offset != read_start) {
	OFF_T ret = do_lseek(map->fd, read_start, SEEK_SET);
	if (ret != read_start) {
	rsyserr(FERROR, errno, "lseek returned %s, not %s",
	big_num(ret), big_num(read_start));
	exit_cleanup(RERR_FILEIO);
	}
	map->p_fd_offset = read_start;
	}
	map->p_offset = window_start;
	map->p_len = window_size;

	while (read_size > 0) {
	int32 nread = read(map->fd, map->p + read_offset, read_size);
	if (nread <= 0) {
	if (!map->status)
	map->status = nread ? errno : ENODATA;
	/* The best we can do is zero the buffer -- the file
	* has changed mid transfer! */
	memset(map->p + read_offset, 0, read_size);
	break;
	}
	map->p_fd_offset += nread;
	read_offset += nread;
	read_size -= nread;
	}

	return map->p + align_fudge;
	}

	int unmap_file(struct map_struct *map)
	{
	int ret;

	if (map->p) {
	free(map->p);
	map->p = NULL;
	}
	ret = map->status;
	#if 0 /* I don't think we really need this. */
	force_memzero(map, sizeof map[0]);
	#endif
	free(map);

	return ret;
	}