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/*
* File IO utilities used in rsync.
*
* Copyright (C) 1998 Andrew Tridgell
* Copyright (C) 2002 Martin Pool
* Copyright (C) 2004-2014 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 boundries. */
#define ALIGN_BOUNDRY 1024
/* How far past the boundary is an offset? */
#define ALIGNED_OVERSHOOT(oft) ((oft) & (ALIGN_BOUNDRY-1))
/* Round up a length to the next boundary */
#define ALIGNED_LENGTH(len) ((((len) - 1) | (ALIGN_BOUNDRY-1)) + 1)
extern int sparse_files;
static OFF_T sparse_seek = 0;
int sparse_end(int f, OFF_T size)
{
int ret;
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;
}
static int write_sparse(int f, 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)
do_lseek(f, sparse_seek, SEEK_CUR);
sparse_seek = l2;
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.
*/
int write_file(int f, 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, buf, len1);
} else {
if (!wf_writeBuf) {
wf_writeBufSize = WRITE_SIZE * 8;
wf_writeBufCnt = 0;
wf_writeBuf = new_array(char, wf_writeBufSize);
if (!wf_writeBuf)
out_of_memory("write_file");
}
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;
}
/* 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;
if (!(map = new0(struct map_struct)))
out_of_memory("map_file");
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);
if (!map->p)
out_of_memory("map_ptr");
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;
memset(map, 0, sizeof map[0]);
free(map);
return ret;
}