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/*
Copyright (C) Andrew Tridgell 1998
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 2 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, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/*
File IO utilities used in rsync
*/
#include "rsync.h"
static char last_byte;
static int last_sparse;
extern int sparse_files;
int sparse_end(int f)
{
if (last_sparse) {
do_lseek(f,-1,SEEK_CUR);
return (write(f,&last_byte,1) == 1 ? 0 : -1);
}
last_sparse = 0;
return 0;
}
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++) ;
last_byte = buf[len-1];
if (l1 == len || l2 > 0)
last_sparse=1;
if (l1 > 0) {
do_lseek(f,l1,SEEK_CUR);
}
if (l1 == len)
return len;
if ((ret=write(f,buf+l1,len-(l1+l2))) != len-(l1+l2)) {
if (ret == -1 || ret == 0) return ret;
return (l1+ret);
}
if (l2 > 0)
do_lseek(f,l2,SEEK_CUR);
return len;
}
int write_file(int f,char *buf,int len)
{
int ret = 0;
if (!sparse_files) {
return write(f,buf,len);
}
while (len>0) {
int len1 = MIN(len, SPARSE_WRITE_SIZE);
int r1 = write_sparse(f, buf, len1);
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)
{
struct map_struct *map;
map = (struct map_struct *)malloc(sizeof(*map));
if (!map) out_of_memory("map_file");
map->fd = fd;
map->file_size = len;
map->p = NULL;
map->p_size = 0;
map->p_offset = 0;
map->p_fd_offset = 0;
map->p_len = 0;
return map;
}
/* slide the read window in the file */
char *map_ptr(struct map_struct *map,OFF_T offset,int len)
{
int nread;
OFF_T window_start, read_start;
int window_size, read_size, read_offset;
if (len == 0) {
return NULL;
}
/* can't go beyond the end of file */
if (len > (map->file_size - offset)) {
len = map->file_size - offset;
}
/* 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 */
if (offset > 2*CHUNK_SIZE) {
window_start = offset - 2*CHUNK_SIZE;
window_start &= ~((OFF_T)(CHUNK_SIZE-1)); /* assumes power of 2 */
} else {
window_start = 0;
}
window_size = MAX_MAP_SIZE;
if (window_start + window_size > map->file_size) {
window_size = map->file_size - window_start;
}
if (offset + len > window_start + window_size) {
window_size = (offset+len) - window_start;
}
/* make sure we have allocated enough memory for the window */
if (window_size > map->p_size) {
map->p = (char *)Realloc(map->p, 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 = 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(FINFO,"Warning: unexpected read size of %d in map_ptr\n", read_size);
} else {
if (map->p_fd_offset != read_start) {
if (do_lseek(map->fd,read_start,SEEK_SET) != read_start) {
rprintf(FERROR,"lseek failed in map_ptr\n");
exit_cleanup(RERR_FILEIO);
}
map->p_fd_offset = read_start;
}
if ((nread=read(map->fd,map->p + read_offset,read_size)) != read_size) {
if (nread < 0) nread = 0;
/* the best we can do is zero the buffer - the file
has changed mid transfer! */
memset(map->p+read_offset+nread, 0, read_size - nread);
}
map->p_fd_offset += nread;
}
map->p_offset = window_start;
map->p_len = window_size;
return map->p + (offset - map->p_offset);
}
void unmap_file(struct map_struct *map)
{
if (map->p) {
free(map->p);
map->p = NULL;
}
memset(map, 0, sizeof(*map));
free(map);
}
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