/*
Copyright (C) Andrew Tridgell 1998
+ Copyright (C) 2002 by Martin Pool
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
}
-static int write_sparse(int f,char *buf,int len)
+static int write_sparse(int f,char *buf,size_t len)
{
- int l1=0,l2=0;
+ size_t l1=0, l2=0;
int ret;
for (l1=0;l1<len && buf[l1]==0;l1++) ;
if (l1 == len || l2 > 0)
last_sparse=1;
- if (l1 > 0)
+ 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;
+ ret = write(f, buf + l1, len - (l1+l2));
+ if (ret == -1 || ret == 0)
+ return ret;
+ else if (ret != (int) (len - (l1+l2)))
return (l1+ret);
- }
if (l2 > 0)
do_lseek(f,l2,SEEK_CUR);
-int write_file(int f,char *buf,int len)
+int write_file(int f,char *buf,size_t len)
{
int ret = 0;
- if (!sparse_files)
+ if (!sparse_files) {
return write(f,buf,len);
+ }
while (len>0) {
int len1 = MIN(len, SPARSE_WRITE_SIZE);
+/* 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 *ret;
- ret = (struct map_struct *)malloc(sizeof(*ret));
- if (!ret) out_of_memory("map_file");
-
- ret->map = NULL;
- ret->fd = fd;
- ret->size = len;
- ret->p = NULL;
- ret->p_size = 0;
- ret->p_offset = 0;
- ret->p_len = 0;
-
-#ifdef USE_MMAP
- len = MIN(len, MAX_MAP_SIZE);
- ret->map = (char *)do_mmap(NULL,len,PROT_READ,MAP_SHARED,fd,0);
- if (ret->map == (char *)-1) {
- ret->map = NULL;
- } else {
- ret->p_len = len;
- }
-#endif
- return ret;
+ 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)
+ if (len == 0) {
return NULL;
+ }
- if (len > (map->size-offset))
- len = map->size-offset;
-
-#ifdef USE_MMAP
- if (map->map) {
- if (offset >= map->p_offset &&
- offset+len <= map->p_offset+map->p_len) {
- return (map->map + (offset - map->p_offset));
- }
- if (munmap(map->map, map->p_len) != 0) {
- rprintf(FERROR,"munmap failed : %s\n", strerror(errno));
- exit_cleanup(RERR_MALLOC);
- }
-
- /* align the mmap region on a nice boundary back a bit from
- where it is asked for to allow for some seeking */
- if (offset > 2*CHUNK_SIZE) {
- map->p_offset = offset - 2*CHUNK_SIZE;
- map->p_offset &= ~((OFF_T)(CHUNK_SIZE-1));
- } else {
- map->p_offset = 0;
- }
-
- /* map up to MAX_MAP_SIZE */
- map->p_len = MAX(len, MAX_MAP_SIZE);
- map->p_len = MIN(map->p_len, map->size - map->p_offset);
-
- map->map = (char *)do_mmap(NULL,map->p_len,PROT_READ,
- MAP_SHARED,map->fd,map->p_offset);
-
- if (map->map == (char *)-1) {
- map->map = NULL;
- map->p_len = 0;
- map->p_offset = 0;
- } else {
- return (map->map + (offset - map->p_offset));
- }
+ /* can't go beyond the end of file */
+ if (len > (map->file_size - offset)) {
+ len = map->file_size - offset;
}
-#endif
+ /* 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));
}
- len = MAX(len,CHUNK_SIZE);
- if (len > (map->size-offset))
- len = map->size-offset;
- if (len > map->p_size) {
- if (map->p) free(map->p);
- map->p = (char *)malloc(len);
- if (!map->p) out_of_memory("map_ptr");
- map->p_size = len;
+ /* 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;
}
- map->p_offset = offset;
- map->p_len = len;
+ /* 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;
+ }
- if (do_lseek(map->fd,offset,SEEK_SET) != offset) {
- rprintf(FERROR,"lseek failed in map_ptr\n");
- exit_cleanup(RERR_FILEIO);
+ /* 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 ((nread=read(map->fd,map->p,len)) != len) {
- if (nread < 0) nread = 0;
- /* the best we can do is zero the buffer - the file
- has changed mid transfer! */
- memset(map->p+nread, 0, len - nread);
+ 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;
+ return map->p + (offset - map->p_offset);
}
void unmap_file(struct map_struct *map)
{
-#ifdef USE_MMAP
- if (map->map) {
- munmap(map->map,map->p_len);
- map->map = NULL;
- }
-#endif
if (map->p) {
free(map->p);
map->p = NULL;
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