/*

* File IO utilities used in rsync.

*

* Copyright (C) 1998 Andrew Tridgell

* Copyright (C) 2002 Martin Pool

* Copyright (C) 2004-2023 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 updating_basis_or_equiv)

{

int ret = 0;

if (updating_basis_or_equiv) {

if (sparse_seek && do_punch_hole(f, sparse_past_write, sparse_seek) < 0)

ret = -1;

#ifdef HAVE_FTRUNCATE /* A compilation formality -- in-place requires ftruncate() */

else /* Just in case the original file was longer */

ret = do_ftruncate(f, size);

#endif

} else if (sparse_seek) {

#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_past_write = 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;

}